Abnormality detection system for hydraulic rotary machine

Abstract

To provide an abnormality detection system for a hydraulic rotary machine, which can accurately detect an abnormality in the hydraulic rotary machine without using a threshold value.SOLUTION: An abnormality detection system 7 for a hydraulic rotary machine 1 according to an embodiment includes a sensor 71 for measuring a drain pressure of the hydraulic rotary machine 1, and a processing circuit 72. The hydraulic rotary machine 1 is an axial piston type including M pistons. The processing circuit 73 performs frequency analysis on a pressure waveform, which is the measuring result of the sensor 71, to create a frequency spectrum, determines the hydraulic rotary machine is normal when the pressure amplitude of a rotational Mth component, which is M times the rotational frequency in the frequency spectrum, is smaller than a predetermined percentage of the pressure amplitude of the rotational first component, which is one time the rotational frequency, and determines that the hydraulic rotary machine is abnormal when the pressure amplitude of the rotational Mth component is larger than the predetermined percentage of the pressure amplitude of the rotational first component.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There are various methods for detecting abnormalities in axial piston hydraulic rotating machines. For example, Patent Document 1 discloses an abnormality detection device that detects abnormalities in an axial piston pump using the discharge pressure or drain pressure of the axial piston pump.

[0003] Specifically, the abnormality detection device in Patent Document 1 measures the discharge pressure or drain pressure of an axial piston pump with a sensor, performs frequency analysis on the pressure waveform measured by the sensor to create a frequency spectrum, and compares the pressure amplitude of the rotation frequency in the frequency spectrum with a threshold value to determine the presence or absence of an abnormality. Note that the rotation frequency is N / 60 [Hz] when the pump speed is N [rpm]. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-170509 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the abnormality detection device of Patent Document 1, it is difficult to set an appropriate threshold value for accurately detecting an abnormality in a hydraulic rotating machine, which is an axial piston pump.

[0006] Therefore, an object of the present disclosure is to provide an abnormality detection system for a hydraulic rotating machine that can accurately detect an abnormality in the hydraulic rotating machine without using a threshold value. [Means for solving the problem]

[0007] From a first aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, the abnormality detection system for a hydraulic rotating machine comprising: a sensor for measuring drain pressure of the hydraulic rotating machine; and a processing circuit for performing frequency analysis on a pressure waveform resulting from the measurement by the sensor to create a frequency spectrum, determining that the hydraulic rotating machine is normal if the pressure amplitude of a rotational Mth order component that is M times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a rotational 1st order component that is 1 time the rotational frequency, and for determining that the hydraulic rotating machine is abnormal if the pressure amplitude of the rotational Mth order component is larger than the predetermined percentage of the pressure amplitude of the rotational 1st order component.

[0008] From a second aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor that measures a drain pressure of the hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the sensor to create a frequency spectrum, and determines that the hydraulic rotating machine is normal if a sum of pressure amplitudes of at least two rotational order components selected from among a second rotational component to an M rotational order component that are 2 to M times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a first rotational component that is 1 time the rotational frequency, and determines that the hydraulic rotating machine is abnormal if the sum is larger than the predetermined percentage of the pressure amplitude of the first rotational component.

[0009] From a third aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor for measuring a drain pressure of the hydraulic rotating machine; and a processing circuit for performing frequency analysis on a pressure waveform resulting from the measurement by the sensor to create a frequency spectrum, determining that the hydraulic rotating machine is normal if a sum of pressure amplitudes of at least two rotational order components selected from among a rotational Mth order component to a rotational (2M)th order component that is M to (2M) times a rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a first rotational component that is 1 time the rotational frequency, and for determining that the hydraulic rotating machine is abnormal if the sum is larger than the predetermined percentage of the pressure amplitude of the first rotational component. Effect of the Invention

[0010] According to the present disclosure, there is provided an abnormality detection system for a hydraulic rotating machine that can accurately detect an abnormality in the hydraulic rotating machine without using a threshold value. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a hydraulic circuit including an axial piston pump, which is a hydraulic rotary machine, and an abnormality detection system according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of an axial piston pump. [Diagram 3] 1 is a graph showing a frequency spectrum created by frequency analysis of a pressure waveform. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First Embodiment Fig. 1 shows an abnormality detection system 7 for a hydraulic rotating machine 1 according to one embodiment. The hydraulic rotating machine 1 is an axial piston type including M pistons 51 as shown in Fig. 2. In this embodiment, the hydraulic rotating machine 1 is an axial piston pump 1A, but the hydraulic rotating machine 1 may also be an axial piston motor.

[0013] As shown in Fig. 1, in this embodiment, an axial piston pump 1A, together with a tank 81 and a plurality of hydraulic actuators 83, constitutes a hydraulic circuit 8 of a construction machine. Although the number of hydraulic actuators 83 is two in Fig. 1, the number of hydraulic actuators 83 may be three or more. The hydraulic fluid used in the hydraulic circuit 8 is typically oil. For example, the construction machine is a hydraulic excavator.

[0014] In this embodiment, the axial piston pump 1A is driven by the engine 10 having L cylinders (L is an even number). However, the axial piston pump 1A may be driven by an electric motor.

[0015] Furthermore, in this embodiment, the axial piston pump 1A is a variable displacement pump. However, when the axial piston pump 1A is driven by an electric motor or depending on the hydraulic circuit 8, the axial piston pump 1A may be a fixed displacement pump.

[0016] 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.

[0017] 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.

[0018] The abnormality detection system 7 includes a sensor 71 that measures the drain pressure of the axial piston pump 1A, and a processing circuit 72 that is electrically connected to the sensor 71.

[0019] An unloading line 96 branches off from the discharge line 93 and is connected to the tank 81. An unloading valve 97 is provided in the unloading line 96.

[0020] In this embodiment, the unloading valve 97 is a spool valve whose spool moves in response to a pilot pressure, and secondary pressure is output as pilot pressure from an electromagnetic proportional valve to the unloading valve 97. The unloading valve 97 is controlled by the processing circuit 72 of the abnormality detection system 7 via the electromagnetic proportional valve. However, the unloading valve 97 may be a solenoid valve whose spool moves in response to an electric signal.

[0021] In this embodiment, the opening degree of the unloading valve 97 is 100% when the spool is in the neutral position, 0% when the spool moves from the neutral position to a predetermined position, and a predetermined ratio when the spool moves further from the predetermined position. In other words, the opening degree of the unloading valve 97 can be arbitrarily changed between a fully open position, which is a neutral state, and a fully closed position, and can be switched to an abnormality detection position where the opening degree becomes the predetermined ratio. The predetermined ratio is, for example, 5% or more and 65% or less. The abnormality detection position is a position for obtaining a pressure waveform, which will be described later.

[0022] However, the abnormality detection position may be a neutral state, and the unloading valve 97 may switch from the abnormality detection position to the fully open position via the fully closed position as the spool moves from the neutral position. Alternatively, the unloading valve 97 does not necessarily have to have an abnormality detection position outside the fully open position and the fully closed position, and a specific position between the fully open position and the fully closed position may be used as the abnormality detection position.

[0023] 2, in this embodiment, the axial piston pump 1A is a swash plate pump. However, the axial piston pump 1A may be a bent axis pump.

[0024] Specifically, the axial piston pump 1A includes a hollow casing 2 and a rotating shaft 11 extending from the inside to the outside of the casing 2. The rotating shaft 11 is connected to an output shaft of an engine 10. A valve plate 3, a cylinder block 4, a swash plate 61, and a support base 62 are arranged within the casing 2.

[0025] For ease of explanation, the axial direction of the rotating shaft 11 will be referred to as the front-to-rear direction (one end side located outside the casing 2 is referred to as the front, and the other end side is 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 in FIG. 2 is referred to as the up, and the lower side is referred to as the down) and the left-right direction.

[0026] The casing 2 includes a container-shaped casing body 21 that opens backward, 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 each hold bearings 12, 13 that rotatably support the rotating shaft 11.

[0027] 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 drawn at the top dead center on the upper side and the second port 32 is drawn at the bottom dead center on the lower side, but the actual positions of the first port 31 and the second port 32 are on both sides of the rotation 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 moved furthest backward, and the bottom dead center is the position where the piston 51 is moved furthest forward.

[0028] 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.

[0029] 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 opposite direction, the second port 32 becomes the suction port and the first port 31 becomes the discharge port.

[0030] The valve cover 22 is provided with a first flow passage 2a communicating with the first port 31 and a second flow passage 2b communicating with the second port 32. The first flow passage 2a and the second flow passage 2b open to the outer circumferential surface or the rear surface 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 passage 2a is the intake passage and the second flow passage 2b is the discharge passage.

[0031] 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 is provided with M cylinder bores 41 that open forward around the periphery of the rotary shaft 11. M pistons 51 are inserted into each of the cylinder bores 41. In this embodiment, M=9.

[0032] 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 of them communicate with the second port 32.

[0033] M shoes 52 are attached to the heads of the pistons 51, respectively. 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 that they are kept in contact with the shoe plates 53.

[0034] The swash plate 61 is supported to be swingable about a swing axis extending in the left-right direction by a support base 62 provided at the bottom of the casing body 21. Although not shown, the axial piston pump 1A is provided with a regulator that swings the swash plate 61.

[0035] The inside of the casing 2 is filled with working fluid that leaks out from between the valve plate 3 and the cylinder block 4, between the piston 51 and the inner circumferential surface of the cylinder bore 41, etc. 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 piping 14. In other words, the inside of the casing 2 and the drain piping 14 constitute the above-mentioned drain line 92.

[0036] In this embodiment, the sensor 71 of the abnormality detection system 7 is provided in the casing body 21. However, the sensor 71 may be provided in the drain pipe 14.

[0037] With respect to the processing circuitry 72, 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 circuits. 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. In the case where the 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 the processor.

[0038] The processing circuit 72 determines whether or not there is an abnormality in the hydraulic rotating machine 1, which is the axial piston pump 1A. In this embodiment, the engine 10 transitions to idling operation when all of the hydraulic actuators 83 are not in operation. In the idling operation, the rotation speed of the engine 10 is kept low.

[0039] During idling operation, the processing circuit 72 switches the unloading valve 97 to the abnormality detection position. This maintains the discharge pressure of the axial piston pump 1A, which is the hydraulic rotating machine 1, at a predetermined value. For example, the predetermined value is 0.01 MPa or more and 3 MPa or less. The processing circuit 72 stores the drain pressure measured by the sensor 71 in this state as a pressure waveform. In other words, the stored pressure waveform is the measurement result of the sensor 71.

[0040] Next, the processing circuit 72 performs frequency analysis on the stored pressure waveform to create a frequency spectrum as shown in Fig. 3. After that, the processing circuit 72 compares the pressure amplitude S9 of the ninth rotational component f9, which is M times, i.e., 9 times, the rotational frequency in the frequency spectrum, with a predetermined ratio R1 (R1 = S9 / S1) of the pressure amplitude S1 of the first rotational component f1, which is 1 time the rotational frequency in the frequency spectrum. The rotational frequency is N / 60 [Hz], where N [rpm] is the rotational speed of the hydraulic rotating machine 1. The predetermined ratio R1 can be determined arbitrarily within the range of 10% to 1000%. For example, the predetermined ratio R1 may be 100% or 50%.

[0041] Figure 3 shows the frequency spectrum when there is an abnormality in the hydraulic rotating machine 1. In the frequency spectrum when the hydraulic rotating machine 1 is normal, the pressure amplitude S9 of the ninth rotational component f9 is small and the pressure amplitude S1 of the first rotational component f1 is large. In contrast, when there is an abnormality in the hydraulic rotating machine 1, the pressure amplitude S9 of the ninth rotational component f9 is larger than the pressure amplitude S1 of the first rotational component f1.

[0042] If the pressure amplitude S9 of the 9th-order rotational component f9 is less than a predetermined ratio R1 of the pressure amplitude S1 of the 1st-order rotational component f1, that is, if S9 < S1 × R1 / 100, the processing circuit 72 determines that it is normal. If the pressure amplitude S9 of the 9th-order rotational component f9 is greater than the predetermined ratio R1 of the pressure amplitude S1 of the 1st-order rotational component f1, that is, if S9 > S1 × R1 / 100, the processing circuit 72 determines that it is abnormal.

[0043] As described above, in the abnormality detection system of the present embodiment, the presence or absence of an abnormality is determined by comparing the pressure amplitude S9 of the 9th-order rotational component f9, which is the Mth-order rotational component, with a predetermined ratio R1 of the pressure amplitude S1 of the 1st-order rotational component f1. Therefore, the abnormality of the hydraulic rotary machine 1 can be detected without using a threshold value. Moreover, according to such a determination method, an abnormality can be accurately detected.

[0044] Furthermore, in the present embodiment, since the processing circuit 72 performs frequency analysis on the pressure waveform measured during idling operation, it is possible to automatically determine the presence or absence of an abnormality each time idling operation is performed, without time loss. Moreover, there is no need to require an operator of the construction machine to perform a troublesome operation such as pressing a drain pressure measurement start button.

[0045] <Second Embodiment> Next, an abnormality detection system according to the second embodiment will be described. The difference between this embodiment and the first embodiment is only the method of determining the presence or absence of an abnormality of the hydraulic rotary machine 1 by the processing circuit 72. This is the same in the third embodiment described later. That is, the processing circuit 72 determines the presence or absence of an abnormality of the hydraulic rotary machine 1 during the idling operation of the engine 10.

[0046] In the present embodiment, the processing circuit 72 compares the sum Z1 of the pressure amplitudes of at least two rotational order components selected from the 2nd-order rotational component f2 to the 9th-order rotational component f9, which are 2 to M times, that is, 9 times the rotational frequency in the frequency spectrum, with a predetermined ratio R2 of the pressure amplitude S1 of the 1st-order rotational component f1. The predetermined ratio R2 can be arbitrarily determined within the range from 10% to 1000%. For example, the predetermined ratio R2 may be 100% or 50%.

[0047] For example, when at least two selected rotational order components are all of the second-order rotational component f2 to the ninth-order rotational component f9, the total Z1 is expressed by the following formula. However, it is desirable that at least two selected rotational order components are the second-order rotational component f2 and the ninth-order rotational component f9.

Equation

[0048] When there is an abnormality in the hydraulic rotary machine 1, not only the pressure amplitude S9 of the ninth-order rotational component f9 but also the pressure amplitudes S2 to S8 of the second-order rotational component f2 to the eighth-order rotational component f8 become larger compared to the pressure amplitude S1 of the first-order rotational component f1.

[0049] If the total Z1 is smaller than a predetermined ratio R2 of the pressure amplitude S1 of the first-order rotational component f1, that is, if Z1 < S1×R2 / 100, the processing circuit 72 determines that it is normal. If the total Z1 is larger than a predetermined ratio R2 of the pressure amplitude S1 of the first-order rotational component f1, that is, if Z1 > S1×R2 / 100, the processing circuit 72 determines that it is abnormal.

[0050] In this embodiment, by comparing the total Z1 of the pressure amplitudes of at least two selected rotational order components among the second-order rotational component f2 to the Mth-order rotational component, which is the ninth-order rotational component f9, with a predetermined ratio R2 of the pressure amplitude S1 of the first-order rotational component f1, the presence or absence of an abnormality is determined. Therefore, the abnormality of the hydraulic rotary machine 1 can be detected without using a threshold value. Moreover, according to such a determination method, the abnormality can be accurately detected.

[0051] When determining the sum Z1, the processing circuit 72 may multiply each of the pressure amplitudes of the at least two selected rotational order components by a coefficient K. For example, when the at least two selected rotational order components are all of the second rotational component f2 to the ninth rotational component f9, the processing circuit 72 may determine the sum Z1 based on the following formula. In this way, the detection accuracy can be improved by weighting with the coefficient K. The coefficient Ki in the formula can be arbitrarily determined for each i within a range from 0.001 to 10.

number

[0052] Furthermore, when the number of cylinders L of the engine 10 that drives the axial piston pump 1A is six, the at least two rotational order components selected may be other than the third rotational component f3, which is a rotational (L / 2)-order component. In this case, the pressure amplitude S3 of the third rotational component f3, which is a rotational (L / 2)-order component, is excluded when determining the sum Z1 of the pressure amplitudes of the rotational order components, so that the pulsation of the drain pressure caused by the engine 10 can be ignored. Note that, since the influence of the pulsation caused by the engine 10 is small on the pressure amplitude S6 of the sixth rotational component f6, which is an L-order rotational component, the sixth rotational component f6 may be included in the at least two rotational order components selected.

[0053] Even when the at least two selected rotational order components are other than the third rotational component f3, the processing circuit 72 may multiply each of the pressure amplitudes of the at least two selected rotational order components by the coefficient K.

[0054] <Third embodiment> Next, an anomaly detection system according to the third embodiment will be described. In this embodiment, the processing circuit 72 compares the sum Z2 of the pressure amplitudes of at least two rotational order components selected from the rotational ninth component f9 to the rotational eighteenth component f18, which are M times, i.e., 9 times to (2M) times, i.e., 18 times the rotational frequency in the frequency spectrum, with a predetermined ratio R3 of the pressure amplitude S1 of the rotational first component f1. The predetermined ratio R3 can be arbitrarily determined within the range from 10% to 1000%. For example, the predetermined ratio R3 may be 100% or may be 50%.

[0055] For example, when at least two selected rotational order components are all the rotational ninth component f9 to the rotational eighteenth component f18, the sum Z2 is expressed by the following formula. However, it is desirable that at least two selected rotational order components are the rotational ninth component f9 and the rotational eighteenth component f18.

Equation

[0056] When there is an anomaly in the hydraulic rotary machine 1, not only the pressure amplitude S9 of the rotational ninth component f9 but also the pressure amplitudes S10 to S18 of the rotational tenth component f10 to the rotational eighteenth component f18 become larger compared to the pressure amplitude S1 of the rotational first component f1.

[0057] If the sum Z2 is smaller than the predetermined ratio R3 of the pressure amplitude S1 of the rotational first component f1, i.e., if Z2 < S1×R3 / 100, the processing circuit 72 determines that it is normal, and if the sum Z2 is larger than the predetermined ratio R3 of the pressure amplitude S1 of the rotational first component f1, i.e., if Z1 > S1×R3 / 100, the processing circuit 72 determines that it is abnormal.

[0058] In this embodiment, the presence or absence of an abnormality is determined by comparing the sum Z2 of the pressure amplitudes of at least two rotational order components selected from the ninth rotational component f9, which is the Mth rotational component, to the 18th rotational component f18, which is the (2M)th rotational component, with a predetermined proportion R3 of the pressure amplitude S9 of the ninth rotational component f9, which is the Mth rotational component, so that an abnormality in the hydraulic rotating machine 1 can be detected without using a threshold value. Moreover, such a determination method allows for accurate detection of an abnormality.

[0059] When determining the sum Z2, the processing circuit 72 may multiply each of the pressure amplitudes of the at least two selected rotational order components by a coefficient K. For example, when the at least two selected rotational order components are all of the ninth rotational order component f9 to the eighteenth rotational order component f18, the processing circuit 72 may determine the sum Z2 based on the following formula. In this way, the detection accuracy can be improved by weighting with the coefficient K. The coefficient Ki in the formula can be arbitrarily determined for each i within a range from 0.001 to 10.

number

[0060] <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.

[0061] For example, the unloading line 96 may also serve as a center bypass line that passes through all of the control valves 82. Furthermore, the axial piston pump 1A may form a hydraulic circuit 8 of a machine other than a construction machine. In this case, the number of hydraulic actuators 83 may be one.

[0062] Furthermore, the determination by the processing circuit 72 of the presence or absence of an abnormality in the hydraulic rotating machine 1 does not necessarily have to be performed while the engine 10 is idling after the axial piston pump 1A, which is the hydraulic rotating machine 1, is installed in a construction machine. For example, the drain pressure may be measured while the discharge pressure of the axial piston pump 1A is kept constant in a manufacturing plant for the axial piston pump 1A, and the processing circuit 72 may determine the presence or absence of an abnormality in the hydraulic rotating machine 1 based on the pressure waveform.

[0063] Alternatively, the determination by the processing circuit 72 of the presence or absence of an abnormality in the hydraulic rotating machine 1 may be performed while any of the hydraulic actuators 83 is in operation. In this case, the processing circuit 72 stores the drain pressure measured by the sensor 71 while the axial piston pump 1A is supplying hydraulic fluid to at least one of the hydraulic actuators 83 as a pressure waveform, and performs frequency analysis on the stored pressure waveform. With this configuration, it is possible to determine the presence or absence of an abnormality when the discharge pressure of the axial piston pump 1A is high, improving the accuracy of abnormality detection. This improves reliability. Moreover, there is no time loss.

[0064] In the case where the hydraulic rotating machine 1 is an axial piston motor, if the drain pressure is measured while the inflow pressure to the axial piston motor is kept constant, it is possible to determine whether or not there is an abnormality in the axial piston motor in a manner similar to that of the above embodiment.

[0065] <Summary> As a first mode, from a first aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, the abnormality detection system for a hydraulic rotating machine comprising: a sensor that measures a drain pressure of the hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform resulting from the measurement by the sensor to create a frequency spectrum, and determines that the hydraulic rotating machine is normal if the pressure amplitude of a rotational Mth order component that is M times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a rotational 1st order component that is 1 time the rotational frequency, and determines that the hydraulic rotating machine is abnormal if the pressure amplitude of the rotational Mth order component is larger than the predetermined percentage of the pressure amplitude of the rotational 1st order component.

[0066] According to the above configuration, the presence or absence of an abnormality is determined by comparing the pressure amplitude of the M-th rotation component with a predetermined ratio of the pressure amplitude of the 1st rotation component, so that an abnormality in the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to this determination method, an abnormality can be accurately detected.

[0067] As a second mode, from a second aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor that measures a drain pressure of the hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the sensor to create a frequency spectrum, and determines that the hydraulic rotating machine is normal if a sum of pressure amplitudes of at least two rotational order components selected from among a second rotational component to an M rotational order component that are 2 to M times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a first rotational component that is 1 time the rotational frequency, and determines that the hydraulic rotating machine is abnormal if the sum is larger than the predetermined percentage of the pressure amplitude of the first rotational component.

[0068] According to the above configuration, the presence or absence of an abnormality is determined by comparing the sum of the pressure amplitudes of at least two rotational order components selected from the second rotational component to the M rotational order component with a predetermined ratio of the pressure amplitude of the first rotational component, so that an abnormality in the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to this determination method, an abnormality can be accurately detected.

[0069] As a third aspect, in the second aspect, the processing circuit may multiply each of the pressure amplitudes of the at least two selected rotational order components by a coefficient when calculating the sum of the pressure amplitudes of the at least two selected rotational order components. With this configuration, it is possible to improve detection accuracy by weighting with the coefficient.

[0070] As a fourth aspect, in the second or third aspect, for example, the at least two selected rotational order components may be the second rotational component and the Mth rotational component.

[0071] As a fifth aspect, in any of the second to fourth aspects, the hydraulic rotating machine is an axial piston pump driven by an engine with L cylinders (L is an even number), and the at least two selected rotational order components may be rotational order components other than the rotational (L / 2) order component. With this configuration, the pressure amplitude of the rotational (L / 2) order component is excluded when calculating the sum of the pressure amplitudes of the rotational order components, so that pulsation of the drain pressure caused by the engine can be ignored.

[0072] As a sixth aspect, from the third aspect, the present disclosure provides an abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor that measures a drain pressure of the hydraulic rotating machine; and a processing circuit that performs frequency analysis on a pressure waveform that is a measurement result of the sensor to create a frequency spectrum, and determines that the hydraulic rotating machine is normal if a sum of pressure amplitudes of at least two rotational order components selected from among a rotational Mth order component to a rotational (2M)th order component that is M times to (2M) times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a first rotational component that is 1 time the rotational frequency, and determines that the hydraulic rotating machine is abnormal if the sum is larger than the predetermined percentage of the pressure amplitude of the first rotational component.

[0073] According to the above configuration, the presence or absence of an abnormality is determined by comparing the sum of the pressure amplitudes of at least two rotational order components selected from the Mth rotational component through the (2Mth) rotational component with a predetermined ratio of the pressure amplitude of the 1st rotational component, so that an abnormality in the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to this determination method, an abnormality can be accurately detected.

[0074] As a seventh aspect, in the sixth aspect, the processing circuit may multiply each of the pressure amplitudes of the at least two selected rotational order components by a coefficient when calculating the sum of the pressure amplitudes of the at least two selected rotational order components. With this configuration, the detection accuracy can be improved by weighting with the coefficient.

[0075] As an eighth aspect, in the sixth or seventh aspect, for example, the at least two selected rotational order components may be the rotational Mth order component and the rotational (2M)th order component.

[0076] As a ninth aspect, in any of the first to eighth aspects, the hydraulic rotating machine is an axial piston pump driven by an engine and constituting a hydraulic circuit of a construction machine together with a plurality of hydraulic actuators, and the processing circuit may store, as the pressure waveform, a drain pressure measured by the sensor while the axial piston pump is supplying hydraulic fluid to at least one of the plurality of hydraulic actuators, and perform frequency analysis on the stored pressure waveform. With this configuration, it is possible to determine the presence or absence of an abnormality when the discharge pressure of the axial piston pump is high, and the accuracy of abnormality detection can be improved. This improves reliability. Moreover, there is no time loss.

[0077] As a tenth aspect, in any one of the first to eighth aspects, the hydraulic rotating machine is an axial piston pump driven by an engine and constituting a hydraulic circuit of a construction machine together with a plurality of hydraulic actuators, the engine transitions to idling operation when the plurality of hydraulic actuators are not in operation, and the processing circuit may store the drain pressure measured by the sensor while the discharge pressure of the axial piston pump is kept at a predetermined value during the idling operation as the pressure waveform, and perform frequency analysis on the stored pressure waveform. With this configuration, it is possible to automatically determine the presence or absence of an abnormality every time the machine is idling, and there is no time loss. Moreover, there is no need to request the operator of the construction machine to perform a troublesome operation such as pressing a drain pressure measurement start button. [Explanation of symbols]

[0078] 1. Hydraulic Rotating Machinery 1A Axial Piston Pump 10 Engine 51 Piston 7 Anomaly Detection System 71 Sensors 72 Processing circuit 8 Hydraulic Circuit 83 Hydraulic Actuator

Claims

1. An abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor for measuring a drain pressure of the hydraulic rotating machine; a processing circuit that performs frequency analysis on the pressure waveform measured by the sensor to create a frequency spectrum, and determines that the pressure amplitude of an M-th order rotational component, which is M times the rotation frequency in the frequency spectrum, is normal if the pressure amplitude is smaller than a predetermined ratio of a 1st order rotational component, which is 1 time the rotation frequency, and determines that the pressure amplitude of the M-th order rotational component is abnormal if the pressure amplitude of the 1st order rotational component is larger than the predetermined ratio; A hydraulic rotating machine abnormality detection system comprising:

2. An abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor for measuring a drain pressure of the hydraulic rotating machine; a processing circuit that performs frequency analysis on the pressure waveform measured by the sensor to create a frequency spectrum, and determines that the pressure waveform is normal if the sum of pressure amplitudes of at least two rotational order components selected from a second rotational component through an M rotational order component that are 2 to M times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of the pressure amplitude of a first rotational component that is 1 time the rotational frequency, and determines that the pressure waveform is abnormal if the sum of the pressure amplitudes is larger than the predetermined percentage of the pressure amplitude of the first rotational component; A hydraulic rotating machine abnormality detection system comprising:

3. 3. The hydraulic rotating machine abnormality detection system according to claim 2, wherein the processing circuit multiplies each of the pressure amplitudes of the at least two selected rotational order components by a coefficient when determining a sum of the pressure amplitudes of the at least two selected rotational order components.

4. 4. The abnormality detection system for a hydraulic rotating machine according to claim 2, wherein the at least two selected rotational order components are the second rotational component and the Mth rotational component.

5. the hydraulic rotary machine is an axial piston pump driven by an engine having L cylinders (L is an even number); 4. The abnormality detection system for a hydraulic rotating machine according to claim 2, wherein the at least two selected rotational order components are rotational order components other than a rotational (L / 2) order component.

6. An abnormality detection system for an axial piston type hydraulic rotating machine including M pistons, comprising: a sensor for measuring a drain pressure of the hydraulic rotating machine; a processing circuit that performs frequency analysis on the pressure waveform measured by the sensor to create a frequency spectrum, and determines that the pressure waveform is normal if a sum of pressure amplitudes of at least two rotational order components selected from among a rotational M-th component through a rotational (2M)-th component that is M-th through (2M)-th times the rotational frequency in the frequency spectrum is smaller than a predetermined percentage of a pressure amplitude of a first rotational component that is 1 times the rotational frequency, and determines that the pressure waveform is abnormal if the sum of the pressure amplitudes is larger than the predetermined percentage of the pressure amplitude of the first rotational component; A hydraulic rotating machine abnormality detection system comprising:

7. 7. The hydraulic rotating machine abnormality detection system according to claim 6, wherein the processing circuit multiplies each of the pressure amplitudes of the at least two selected rotational order components by a coefficient when determining a sum of the pressure amplitudes of the at least two selected rotational order components.

8. 8. The abnormality detection system for a hydraulic rotating machine according to claim 6, wherein the at least two selected rotational order components are the M-th rotational component and the (2M)-th rotational order component.

9. the hydraulic rotating machine is an axial piston pump that is driven by an engine and that, together with a plurality of hydraulic actuators, constitutes a hydraulic circuit of a construction machine; 8. The hydraulic rotating machine abnormality detection system according to claim 1, wherein the processing circuit stores, as the pressure waveform, a drain pressure measured by the sensor while the axial piston pump supplies working fluid to at least one of the plurality of hydraulic actuators, and performs frequency analysis on the stored pressure waveform.

10. the hydraulic rotating machine is an axial piston pump that is driven by an engine and that, together with a plurality of hydraulic actuators, constitutes a hydraulic circuit of a construction machine; the engine transitions to an idling operation when the plurality of hydraulic actuators are not in operation; 8. The hydraulic rotating machine anomaly detection system according to claim 1, wherein the processing circuit stores, as the pressure waveform, the drain pressure measured by the sensor while the discharge pressure of the axial piston pump is maintained at a predetermined value during the idling operation, and performs frequency analysis on the stored pressure waveform.

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