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 sensor (71) that measures a discharge pressure of the hydraulic rotary machine (1), and a processing circuit (72). The hydraulic rotary machine (1) is of the axial piston type comprising M pistons. A processing circuit (73) performs frequency analysis on a pressure waveform as a measurement result of a sensor (71), creates a frequency spectrum, and determines that the pressure waveform is normal if the pressure amplitude of a rotation M-order component, which is M times the rotation frequency in the frequency spectrum, is less than a predetermined ratio of the pressure amplitude of a rotation 1-order component, which is one time the rotation frequency, and determines that the pressure waveform is normal if the pressure amplitude is less than a predetermined ratio of the pressure amplitude of the rotation 1-order component. If the pressure amplitude of the M-order rotation component is greater than the predetermined ratio of the pressure amplitude of the first-order rotation component, it is determined that there is an abnormality.

Description

Technical Field

[0001] The invention relates to an abnormality detection system for a hydraulic rotary machine. Background Art

[0002] There are various methods for detecting abnormalities in axial piston hydraulic rotary machines. For example, Japanese Patent Application Laid-Open No. 2013-170509 discloses an abnormality detection device for detecting abnormalities in an axial piston pump using the discharge pressure or drain pressure of the axial piston pump.

[0003] Specifically, the abnormality detection device of Japanese Patent Publication No. 2013-170509 measures the discharge pressure or discharge pressure of the axial piston pump through a sensor, performs frequency analysis on the pressure waveform as the measurement result of the sensor and creates a frequency spectrum, and compares the pressure amplitude of the rotation frequency in the spectrum with a threshold value to determine whether there is an abnormality. In addition, the rotation frequency is N / 60 [Hz] when the rotation speed of the pump is N [rpm]. Summary of the invention

[0004] However, in the abnormality detection device of Japanese Patent Application Laid-Open No. 2013-170509, it is difficult to set an appropriate threshold value for accurately detecting an abnormality of the hydraulic rotary machine, which is the axial piston pump.

[0005] Therefore, an object of the present disclosure is to provide an abnormality detection system for a hydraulic rotary machine that can accurately detect an abnormality of the hydraulic rotary machine without using a threshold value.

[0006] The present disclosure provides, from a first aspect, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as the measurement result of the sensor and producing a spectrum, and if the pressure amplitude of M times the rotation frequency in the spectrum, that is, the Mth-order rotation component, is smaller than a specified ratio of the pressure amplitude of 1 times the rotation frequency, that is, the first-order rotation component, it is judged to be normal, and if the pressure amplitude of the Mth-order rotation component is larger than the specified ratio of the pressure amplitude of the first-order rotation component, it is judged to be abnormal.

[0007] The present disclosure provides, from a second aspect, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as the measurement result of the sensor and producing a spectrum, and if the sum of the pressure amplitudes of at least two rotational order components selected from 2 to M times the rotational frequency in the spectrum, that is, the rotational 2nd order component to the rotational Mth order component, is less than a specified ratio of the pressure amplitude of 1 times the rotational frequency, that is, the rotational 1st order component, it is judged to be normal, and if the sum is greater than the specified ratio of the pressure amplitude of the rotational 1st order component, it is judged to be abnormal.

[0008] The present disclosure provides, from a third aspect, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as the measurement result of the sensor and producing a spectrum, if the sum of the pressure amplitudes of at least two rotational order components selected from M times to (2M) times the rotational frequency in the spectrum, that is, the rotational M-order component to the rotational (2M)-order component, is less than 1 times the rotational frequency, that is, a specified ratio of the pressure amplitude of the rotational 1st-order component, it is judged to be normal, and if the sum is greater than the specified ratio of the pressure amplitude of the rotational 1st-order component, it is judged to be abnormal.

[0009] According to the present disclosure, there is provided an abnormality detection system for a hydraulic rotary machine capable of accurately detecting an abnormality of the hydraulic rotary machine without using a threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram showing a hydraulic circuit including an axial piston pump as a hydraulic rotary machine and an abnormality detection system according to one embodiment; Figure 2 is a cross-sectional view of an axial piston pump; Figure 3 This is a graph showing a frequency spectrum created by frequency analysis of a pressure waveform. DETAILED DESCRIPTION

[0011] <First embodiment> Figure 1 FIG. 7 shows an abnormality detection system 7 for a hydraulic rotary machine 1 according to an embodiment. Figure 2 As shown, it is an axial piston type including M pistons 51. In the present embodiment, the hydraulic rotary machine 1 is an axial piston pump 1A, but the hydraulic rotary machine 1 may also be an axial piston motor.

[0012] like Figure 1As shown, in the present embodiment, the axial piston pump 1A, the tank 81 and the plurality of hydraulic actuators 83 constitute a hydraulic circuit 8 of a construction machine. Figure 1 The number of hydraulic actuators 83 is two, but the number of hydraulic actuators 83 may be three or more. The working fluid used in the hydraulic circuit 8 is usually oil. For example, the construction machine is a hydraulic excavator.

[0013] In the present embodiment, the axial piston pump 1A is driven by the L-cylinder (L is an even number) engine 10. However, the axial piston pump 1A may be driven by an electric motor.

[0014] In addition, in the present 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 according to the hydraulic circuit 8, the axial piston pump 1A may be a fixed displacement pump.

[0015] 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 via a pair of supply and discharge lines 95. Each hydraulic actuator 83 may be a hydraulic cylinder or a hydraulic motor.

[0016] The axial piston pump 1A is connected to the tank 81 via a suction line 91 and to all control valves 82 via a discharge line 93. All control valves 82 are connected to the tank 81 via a tank line 94. The axial piston pump 1A is connected to the tank 81 via a discharge line 92.

[0017] The abnormality detection system 7 includes a sensor 71 for measuring the discharge pressure of the axial piston pump 1A and a processing circuit 72 electrically connected to the sensor 71 .

[0018] The unloading line 96 branches off from the discharge line 93, and the unloading line 96 is connected to the tank 81. The unloading line 96 is provided with an unloading valve 97.

[0019] In this embodiment, the unloading valve 97 is a spool valve whose valve core moves according to the pilot pressure, and the secondary pressure is output as the pilot pressure from the 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 also be an electromagnetic valve whose valve core moves according to an electrical signal.

[0020] In this embodiment, the opening of the unloading valve 97 is 100% when the valve core is in the neutral position, becomes 0% when the valve core moves from the neutral position to the specified position, and becomes a specified ratio when the valve core moves further from the specified position. In other words, the opening of the unloading valve 97 can be arbitrarily changed between the fully open position and the fully closed position as the neutral state, and the opening can be switched to the abnormal detection position that becomes the specified ratio. The specified ratio is, for example, 5% to 65%. The abnormal detection position is a position for obtaining the pressure waveform described later.

[0021] However, the abnormality detection position may be in 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 valve core moves from the neutral position. Alternatively, the unloading valve 97 does not necessarily need 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.

[0022] like Figure 2 As shown, in this embodiment, the axial piston pump 1A is a swash plate pump. However, the axial piston pump 1A may also be a slant axis pump.

[0023] Specifically, the axial piston pump 1A includes a hollow housing 2 and a rotating shaft 11 extending from the inside to the outside of the housing 2. The rotating shaft 11 is connected to the output shaft of the engine 10. The housing 2 contains a valve plate 3, a cylinder block 4, a swash plate 61, and a support base 62.

[0024] In the following, for convenience of explanation, the axial direction of the rotating shaft 11 is referred to as the front-rear direction (one end side located outside the housing 2 is the front, and the other end side is the rear), and the two directions orthogonal to the axial direction of the rotating shaft 11 are referred to as the up-down direction ( Figure 2 The upper side is upward, and the lower side is downward) and left and right directions.

[0025] The housing 2 includes a container-shaped housing body 21 opened rearward and a valve cover 22 that closes the opening of the housing body 21. The rotating shaft 11 passes through the bottom of the housing body 21. The bottom of the housing body 21 and the valve cover 22 respectively hold bearings 12 and 13 that rotatably support the rotating shaft 11.

[0026] The valve plate 3 is mounted on the front surface of the valve cover 22. The valve plate 3 is provided with a first port 31 and a second port 32 in an arc shape which are opposite to each other. Figure 2 In the figure, the first port 31 is drawn at the upper top dead center and the second port 32 is drawn at the lower bottom dead center, but the actual positions of the first port 31 and the second port 32 are on both sides of the rotating shaft 11 in the left-right direction orthogonal to the separation direction of the top dead center and the bottom dead center. The top dead center is the position where the piston 51 described later is most retracted, and the bottom dead center is the position where the piston 51 is most advanced.

[0027] In this embodiment, the rotating shaft 11 rotates in one direction. Therefore, the first port 31 is an inlet port, and the second port 32 is an outlet port. That is, in the rotation direction of the rotating shaft 11, the first port 31 as an inlet port is located on the downstream side of the top dead center and the upstream side of the bottom dead center, and the second port 32 as an outlet port is located on the downstream side of the bottom dead center and the upstream side of the top dead center.

[0028] However, the rotating shaft 11 may be rotated in two directions by the hydraulic circuit 8. In this case, when the rotating shaft 11 rotates in one direction, the first port 31 is the suction port and the second port 32 is the discharge port, and when the rotating shaft 11 rotates in the opposite direction, the second port 32 is the suction port and the first port 31 is the discharge port.

[0029] 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 are opened on the outer peripheral surface or the rear surface of the valve cover 22, and these openings form external connection ports. As described above, in this embodiment, the rotating shaft 11 rotates in one direction, the first flow path 2a is the suction path, and the second flow path 2b is the discharge path.

[0030] The cylinder body 4 is fixed to the rotating shaft 11, rotates with the rotating shaft 11 and slides with the valve plate 3. The cylinder body 4 is provided with M cylinder holes 41 opening forward around the rotating shaft 11. M pistons 51 are inserted into each of the cylinder holes 41. In this embodiment, M=9.

[0031] The cylinder block 4 is provided with cylinder ports 42 extending from the cylinder holes 41 to the valve plate 3 . Some of the cylinder ports 42 are communicated with the first port 31 , and the other ones are communicated with the second port 32 .

[0032] M slide shoes 52 are respectively mounted on the head of the piston 51. In the present embodiment, the slide shoes 52 slide on the swash plate 61 via the annular support plate 53 mounted on the swash plate 61. However, the support plate 53 may be omitted, and the slide shoes 52 slide directly on the swash plate 61. The slide shoes 52 are pressed by the pressure plate 54 to maintain a state of contact with the support plate 53.

[0033] The swash plate 61 is supported so as to be swingable about a swing shaft extending in the left-right direction by a support stand 62 provided at the bottom of the housing body 21. Although not shown in the figure, the axial piston pump 1A is provided with a regulator for swinging the swash plate 61.

[0034] The interior of the housing 2 is filled with the working fluid leaking from between the valve plate 3 and the cylinder body 4 or between the piston 51 and the inner peripheral surface of the cylinder hole 41. The housing body 21 is provided with a discharge port 23, and the discharge port 23 is connected to the tank 81 through the discharge pipe 14. That is, the interior of the housing 2 and the discharge pipe 14 constitute the above-mentioned discharge line 92.

[0035] In this embodiment, the sensor 71 of the abnormality detection system 7 is provided in the housing body 21. However, the sensor 71 may be provided in the discharge pipe 14.

[0036] Regarding the processing loop 72, the functions of the elements disclosed in this specification can be performed using a circuit or processing circuit that includes a general-purpose processor, a special-purpose processor, an integrated circuit, an ASIC (Application Specific Integrated Circuits), an existing circuit and / or a combination thereof that is constructed or programmed to perform the disclosed functions. The processor is considered to be a processing circuit or circuit because it includes transistors or other circuits. In the present disclosure, a circuit, unit or means is hardware that performs the listed functions, or hardware that is programmed to perform the listed functions. The hardware can be the hardware disclosed in this specification, or other known hardware that is programmed or constructed to perform the listed functions. When the hardware is considered to be a processor of a circuit, the circuit, means or unit is a combination of hardware and software, and the software is used in the construction of the hardware and / or processor.

[0037] The processing circuit 72 determines whether the hydraulic rotary machine 1, which is the axial piston pump 1A, has an abnormality. In the present embodiment, the engine 10 shifts to an idling operation when all the hydraulic actuators 83 are not in operation. During the idling operation, the rotation speed of the engine 10 is kept low.

[0038] The processing circuit 72 switches the unloading valve 97 to the abnormality detection position during idling. As a result, the discharge pressure of the axial piston pump 1A as the hydraulic rotary machine 1 is maintained 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 discharge pressure measured by the sensor 71 in this state as a pressure waveform. That is, the stored pressure waveform is the measurement result of the sensor 71.

[0039] Next, the processing circuit 72 performs frequency analysis on the stored pressure waveform to produce Figure 3 The frequency spectrum shown. Then, the processing circuit 72 compares the pressure amplitude S9 of the 9th-order rotation component f9, which is M times, i.e., 9 times, the rotation frequency in the frequency spectrum, with the prescribed ratio R1 (R1=S9 / S1) of the pressure amplitude S1 of the 1st-order rotation component f1, which is 1 times the rotation frequency in the frequency spectrum. The rotation frequency is N / 60 [Hz] when the rotation speed of the hydraulic rotary machine 1 is N [rpm]. The prescribed ratio R1 can be arbitrarily determined within the range from 10% to 1000%. For example, the prescribed ratio R1 can be 100% or 50%.

[0040] Figure 3This is the frequency spectrum when the hydraulic rotary machine 1 is abnormal. In the frequency spectrum when the hydraulic rotary machine 1 is normal, the pressure amplitude S9 of the rotating 9th order component f9 is small, and the pressure amplitude S1 of the rotating 1st order component f1 is large. In contrast, when the hydraulic rotary machine 1 is abnormal, the pressure amplitude S9 of the rotating 9th order component f9 becomes larger than the pressure amplitude S1 of the rotating 1st order component f1.

[0041] If the pressure amplitude S9 of the rotating 9th-order component f9 is smaller than the specified ratio R1 of the pressure amplitude S1 of the rotating 1st-order component f1, that is, if S9<S1×R1 / 100, the processing circuit 72 is judged to be normal; if the pressure amplitude S9 of the rotating 9th-order component f9 is larger than the specified ratio R1 of the pressure amplitude S1 of the rotating 1st-order component f1, that is, if S9>S1×R1 / 100, it is judged to be abnormal.

[0042] As described above, in the abnormality detection system 7 of the present embodiment, the presence or absence of abnormality is determined by comparing the pressure amplitude S9 of the rotating 9th-order component f9, which is the rotating Mth-order component, with the predetermined ratio R1 of the pressure amplitude S1 of the rotating 1st-order component f1, so that the abnormality of the hydraulic rotating machine 1 can be detected without using a threshold value. Moreover, according to such a determination method, the abnormality can be accurately detected.

[0043] In addition, in this embodiment, the processing circuit 72 performs frequency analysis on the pressure waveform measured during idling operation, so that the presence or absence of abnormality can be automatically determined each time the idling operation is performed without wasting time. In addition, there is no need to perform cumbersome operations such as requiring the operator of the construction machine to press a button to start the discharge pressure measurement.

[0044] <Second embodiment> Next, the abnormality detection system of the second embodiment is described. The only difference between this embodiment and the first embodiment is the method of determining whether the hydraulic rotary machine 1 has an abnormality by the processing circuit 72. This point is also the same in the third embodiment described later. That is, the processing circuit 72 determines whether the hydraulic rotary machine 1 has an abnormality during the idling operation of the engine 10.

[0045] In this embodiment, the processing circuit 72 compares the total Z1 of the pressure amplitudes of at least two rotational order components selected from the rotational second order component f2 to the rotational ninth order component f9, which are 2 to M times, i.e., 9 times, the rotational frequency in the spectrum, with the prescribed ratio R2 of the pressure amplitude S1 of the rotational first order component f1. The prescribed ratio R2 can be arbitrarily determined within the range of 10% to 1000%. For example, the prescribed ratio R2 can be 100% or 50%.

[0046] For example, when the at least two selected rotation order components are all of the rotation 2nd order component f2 to the rotation 9th order component f9, the total Z1 is expressed by the following formula. However, the at least two selected rotation order components are preferably the rotation 2nd order component f2 and the rotation 9th order component f9; [Number 1]

[0047] When the hydraulic rotary machine 1 is abnormal, not only the pressure amplitude S9 of the 9th-order rotating component f9 but also the pressure amplitudes S2 to S8 of the 2nd-order rotating components f2 to the 8th-order rotating components f8 increase compared to the pressure amplitude S1 of the 1st-order rotating component f1.

[0048] If the total Z1 is smaller than the specified ratio R2 of the pressure amplitude S1 of the rotating first-order component f1, that is, if Z1<S1×R2 / 100, the processing circuit 72 is judged to be normal; if the total Z1 is larger than the specified ratio R2 of the pressure amplitude S1 of the rotating first-order component f1, that is, if Z1>S1×R2 / 100, it is judged to be abnormal.

[0049] In this embodiment, the presence or absence of abnormality is determined by comparing the total Z1 of the pressure amplitudes of at least two rotation order components selected from the rotation 2nd order component f2 to the rotation 9th order component f9 which is the rotation Mth order component with the predetermined ratio R2 of the pressure amplitude S1 of the rotation 1st order component f1, so that 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 detected correctly.

[0050] In addition, the processing circuit 72 may also multiply the pressure amplitudes of the selected at least two rotation order components by the coefficient K when calculating the total Z1. For example, when the selected at least two rotation order components are all of the rotation 2nd order component f2 to the rotation 9th order component f9, the processing circuit 72 may calculate the total Z1 based on the following formula. In this way, the detection accuracy can be improved by weighting the coefficient K. In addition, the coefficient Ki in the formula can be arbitrarily determined for each i within the range of 0.001 to 10; [Number 2]

[0051] Furthermore, when the number of cylinders L of the engine 10 driving the axial piston pump 1A is 6, the at least two selected rotational order components may be rotational order components other than the rotational third order component f3 which is the rotational (L / 2) order component. In this case, when the total pressure amplitude Z1 of the rotational order components is obtained, the pressure amplitude S3 of the rotational third order component f3 which is the rotational (L / 2) order component is excluded, so the pulsation of the discharge pressure caused by the engine 10 can be ignored. In addition, the influence of the pulsation caused by the engine 10 is small compared to the pressure amplitude S6 of the rotational sixth order component f6 which is the rotational L order component, so the rotational sixth order component f6 may be included in the at least two selected rotational order components.

[0052] Even when the selected at least two rotation order components are rotation order components other than the rotation third order component f3, the processing circuit 72 may respectively multiply the pressure amplitudes of the selected at least two rotation order components by the coefficient K.

[0053] <Third embodiment> Next, the abnormality detection system of the third embodiment is described. In this embodiment, the processing circuit 72 compares the total Z2 of the pressure amplitudes of at least two rotational order components selected from the rotational 9th ​​order component f9 to the rotational 18th order component f18, which are M times, i.e., 9 times to (2M) times, i.e., 18 times, the rotational frequency in the spectrum, with the prescribed ratio R3 of the pressure amplitude S1 of the rotational 1st order component f1. The prescribed ratio R3 can be arbitrarily determined within the range of 10% to 1000%. For example, the prescribed ratio R3 can be 100% or 50%.

[0054] For example, when the at least two selected rotation order components are all of the rotation 9th order component f9 to the rotation 18th order component f18, the total Z2 is expressed by the following formula. However, the at least two selected rotation order components are preferably the rotation 9th order component f9 and the rotation 18th order component f18; [Number 3]

[0055] When the hydraulic rotary machine 1 is abnormal, compared with the pressure amplitude S1 of the 1st-order rotation component f1, not only the pressure amplitude S9 of the 9th-order rotation component f9 increases, but also the pressure amplitudes S10 to S18 of the 10th-order rotation components f10 to 18th-order rotation components f18 increase.

[0056] If the total Z2 is smaller than the prescribed ratio R3 of the pressure amplitude S1 of the rotating first-order component f1, that is, if Z2<S1×R3 / 100, the processing circuit 72 is judged to be normal; if the total Z2 is larger than the prescribed ratio R3 of the pressure amplitude S1 of the rotating first-order component f1, that is, if Z1>S1×R3 / 100, it is judged to be abnormal.

[0057] In this embodiment, the presence or absence of abnormality is determined by comparing the total Z2 of the pressure amplitudes of at least two rotation order components selected from the rotation 9th order component f9 as the rotation Mth order component to the rotation 18th order component f18 as the rotation (2M)th order component with the prescribed ratio R3 of the pressure amplitude S9 of the rotation 9th order component f9 as the rotation Mth order component, so that 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 detected correctly.

[0058] In addition, the processing circuit 72 may also multiply the pressure amplitudes of the selected at least two rotation order components by the coefficient K when calculating the total Z2. For example, when the selected at least two rotation order components are all of the rotation 9th order component f9 to the rotation 18th order component f18, the processing circuit 72 may calculate the total Z2 based on the following formula. In this way, the detection accuracy can be improved by weighting the coefficient K. In addition, the coefficient Ki in the formula can be arbitrarily determined for each i within the range of 0.001 to 10; [Number 4]

[0059] <Other embodiments> The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope not departing from the gist of the present disclosure.

[0060] For example, the unloading line 96 may also serve as a central bypass line passing through all the control valves 82. Furthermore, the axial piston pump 1A may constitute the hydraulic circuit 8 of a machine other than a construction machine. In this case, the number of the hydraulic actuator 83 may be one.

[0061] Furthermore, the determination of the presence or absence of an abnormality in the hydraulic rotary machine 1 by the processing circuit 72 does not necessarily have to be performed during the idling operation of the engine 10 after the axial piston pump 1A as the hydraulic rotary machine 1 is assembled in the construction machine. For example, the discharge pressure may be measured in a manufacturing plant of the axial piston pump 1A while the discharge pressure of the axial piston pump 1A is kept constant, and the processing circuit 72 may determine the presence or absence of an abnormality in the hydraulic rotary machine 1 based on the pressure waveform.

[0062] Alternatively, the determination of the presence or absence of an abnormality in the hydraulic rotary machine 1 by the processing circuit 72 may be performed during the operation of any of the hydraulic actuators 83. In this case, the processing circuit 72 stores the discharge pressure measured by the sensor 71 during the period when the axial piston pump 1A supplies working 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 structure, it is possible to determine the presence or absence of an abnormality when the discharge pressure of the axial piston pump 1A is high, and the accuracy of abnormality detection can be improved. As a result, reliability is improved. In addition, there is no time loss.

[0063] When the hydraulic rotary machine 1 is an axial piston motor, if the discharge pressure is measured while the inflow pressure of the axial piston motor is kept constant, the presence or absence of abnormality in the axial piston motor can be determined by the same method as in the above embodiment.

[0064] Summary As a first form, the present disclosure provides, from a first aspect, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as a measurement result of the sensor and producing a spectrum, and if the pressure amplitude of M times the rotation frequency in the spectrum, that is, the Mth-order rotation component, is smaller than a specified ratio of the pressure amplitude of 1 times the rotation frequency, that is, the first-order rotation component, it is judged to be normal, and if the pressure amplitude of the Mth-order rotation component is larger than the specified ratio of the pressure amplitude of the first-order rotation component, it is judged to be abnormal.

[0065] According to the above configuration, the presence or absence of abnormality is determined by comparing the pressure amplitude of the rotating Mth order component with the pressure amplitude of the rotating 1st order component at a predetermined ratio, so that abnormality of the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to such a determination method, abnormality can be detected accurately.

[0066] As a second form, the present disclosure provides, from a second side, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as a measurement result of the sensor and producing a spectrum, if the sum of the pressure amplitudes of at least two rotational order components selected from 2 to M times the rotational frequency in the spectrum, that is, the second-order rotational component to the M-order rotational component, is less than a specified ratio of the pressure amplitude of 1 times the rotational frequency, that is, the first-order rotational component, it is judged to be normal, and if the sum is greater than the specified ratio of the pressure amplitude of the first-order rotational component, it is judged to be abnormal.

[0067] 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 rotational 2nd order component to the rotational Mth order component with a predetermined ratio of the pressure amplitude of the rotational 1st order component, so that an abnormality of the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to such a determination method, an abnormality can be accurately detected.

[0068] As a third aspect, in the second aspect, the processing circuit may multiply the pressure amplitudes of the at least two selected rotation order components by coefficients when calculating the sum of the pressure amplitudes of the at least two selected rotation order components. According to this structure, the detection accuracy can be improved by weighting the coefficients.

[0069] As a fourth aspect, in the second or third aspect, for example, the selected at least two rotational order components are the rotational 2nd order component and the rotational Mth order component.

[0070] As a fifth aspect, in any one of the second to fourth aspects, the hydraulic rotary machine may be an axial piston pump driven by an L-cylinder (L is an even number) engine, and the selected at least two rotation order components are rotation order components other than the rotation (L / 2) order component. According to this structure, when calculating the total pressure amplitude of the rotation order components, the pressure amplitude of the rotation (L / 2) order component is excluded, and the pulsation of the discharge pressure caused by the engine can be ignored.

[0071] As a sixth form, the present disclosure provides, from the third aspect, an abnormality detection system for a hydraulic rotating machinery, which is an abnormality detection system for an axial piston type hydraulic rotating machinery including M pistons, and comprises: a sensor for measuring the discharge pressure of the hydraulic rotating machinery; and a processing circuit for performing frequency analysis on the pressure waveform as a measurement result of the sensor and producing a spectrum, if the sum of the pressure amplitudes of at least two rotational order components selected from M times to (2M) times the rotational frequency in the spectrum, that is, the rotational M-order component to the rotational (2M)-order component, is less than 1 times the rotational frequency, that is, a specified ratio of the pressure amplitude of the rotational 1st-order component, it is judged to be normal, and if the sum is greater than the specified ratio of the pressure amplitude of the rotational 1st-order component, it is judged to be abnormal.

[0072] 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 rotation order components selected from the rotation M order component to the rotation (2M) order component with a predetermined ratio of the pressure amplitude of the rotation 1 order component, so that an abnormality of the hydraulic rotating machine can be detected without using a threshold value. Moreover, according to such a determination method, an abnormality can be accurately detected.

[0073] As a seventh aspect, in the sixth aspect, when the processing circuit calculates the sum of the pressure amplitudes of the at least two selected rotation order components, it may multiply the pressure amplitudes of the at least two selected rotation order components by coefficients. According to this structure, the detection accuracy can be improved by weighting the coefficients.

[0074] As an eighth aspect, in the sixth or seventh aspect, for example, the selected at least two rotational order components are the rotational M-order component and the rotational (2M)-order component.

[0075] As a ninth aspect, in any one of the first to eighth aspects, the hydraulic rotary machine is an axial piston pump that is driven by an engine and constitutes a hydraulic circuit of a construction machine together with a plurality of hydraulic actuators, and the processing circuit stores the discharge pressure measured by the sensor as the pressure waveform during the period when 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. According to this structure, when the discharge pressure of the axial piston pump is high, it is possible to determine whether there is an abnormality, and the accuracy of abnormality detection can be improved. As a result, reliability is improved. In addition, there is no time loss.

[0076] As a tenth form, in any one of the first to eighth forms, the hydraulic rotary machine is an axial piston pump driven by an engine and constitutes a hydraulic circuit of a construction machine together with a plurality of hydraulic actuators, the engine shifts to idling operation when the plurality of hydraulic actuators are not in operation, and the processing circuit stores the discharge pressure measured by the sensor as the pressure waveform while the discharge pressure of the axial piston pump is maintained at a specified value during the idling operation, and performs frequency analysis on the stored pressure waveform. According to this structure, the presence or absence of abnormalities can be automatically determined each time the idling operation is performed without time loss. In addition, there is no need to perform complicated operations such as requiring the operator of the construction machine to press a button to start the discharge pressure measurement.

Claims

1. A hydraulic rotary machine abnormality detection system, characterized in that: This is an abnormality detection system for axial piston hydraulic rotary machinery including M pistons, and has: a sensor that measures a discharge pressure of the hydraulic rotary machine; and A processing circuit performs frequency analysis on the pressure waveform as the measurement result of the sensor and produces a spectrum. If the pressure amplitude of M times the rotation frequency, that is, the pressure amplitude of the M-order rotation component in the spectrum is smaller than a specified ratio of 1 times the rotation frequency, that is, the pressure amplitude of the 1st-order rotation component, it is judged to be normal. If the pressure amplitude of the M-order rotation component is larger than the specified ratio of the pressure amplitude of the 1st-order rotation component, it is judged to be abnormal.

2. A hydraulic rotary machinery abnormality detection system, characterized in that: This is an abnormality detection system for axial piston hydraulic rotary machinery including M pistons, and has: a sensor that measures a discharge pressure of the hydraulic rotary machine; and A processing circuit performs frequency analysis on the pressure waveform as a measurement result of the sensor and produces a spectrum, and judges it to be normal if the sum of the pressure amplitudes of at least two rotational order components selected from 2 times to M times of the rotational frequency in the spectrum, that is, the second-order rotational component to the M-order rotational component, is less than a specified ratio of the pressure amplitude of 1 times the rotational frequency, that is, the first-order rotational component; and judges it to be abnormal if the sum is greater than the specified ratio of the pressure amplitude of the first-order rotational component.

3. The abnormality detection system for hydraulic rotary machinery according to claim 2, characterized in that: The processing circuit multiplies the pressure amplitudes of the at least two selected rotation order components by coefficients when calculating the sum of the pressure amplitudes of the at least two selected rotation order components.

4. The abnormality detection system for hydraulic rotary machinery according to claim 2 or 3, characterized in that: The selected at least two rotational order components are the rotational 2nd order component and the rotational Mth order component.

5. The abnormality detection system for hydraulic rotary machinery according to claim 2 or 3, characterized in that: The hydraulic rotary machine is an axial piston pump driven by an L-cylinder (L is an even number) engine; The selected at least two rotational order components are rotational order components other than the rotational (L / 2) order component.

6. A hydraulic rotary machine abnormality detection system, characterized in that: This is an abnormality detection system for axial piston hydraulic rotary machinery including M pistons, and has: a sensor that measures a discharge pressure of the hydraulic rotary machine; and A processing circuit performs frequency analysis on the pressure waveform as a measurement result of the sensor and produces a spectrum, and judges it to be normal if the sum of the pressure amplitudes of at least two rotational order components selected from M times to (2M) times the rotational frequency in the spectrum, that is, the M-order rotational component to the (2M)-order rotational component, is less than 1 times the rotational frequency, that is, a specified ratio of the pressure amplitude of the 1st-order rotational component; and judges it to be abnormal if the sum is greater than the specified ratio of the pressure amplitude of the 1st-order rotational component.

7. The abnormality detection system for hydraulic rotary machinery according to claim 6, characterized in that: The processing circuit multiplies the pressure amplitudes of the at least two selected rotation order components by coefficients when calculating the sum of the pressure amplitudes of the at least two selected rotation order components.

8. The abnormality detection system for hydraulic rotary machinery according to claim 6 or 7, characterized in that: The selected at least two rotational order components are the rotational M-order component and the rotational (2M)-order component.

9. The abnormality detection system for a hydraulic rotary machine according to any one of claims 1 to 3, 6 and 7, characterized in that: The hydraulic rotary 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 processing circuit stores the discharge pressure measured by the sensor as the pressure waveform while the axial piston pump supplies the working fluid to at least one of the plurality of hydraulic actuators, and performs frequency analysis on the stored pressure waveform.

10. The abnormality detection system for a hydraulic rotary machine according to any one of claims 1 to 3, 6 and 7, characterized in that: The hydraulic rotary 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 shifts to idle operation when the plurality of hydraulic actuators are not in operation; The processing circuit stores the discharge pressure measured by the sensor as the pressure waveform in a state where 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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