Method for evaluating the remaining service life of a component in a hydraulic system, and associated electronic device

Abstract

Method for evaluating the remaining service life of a component in a hydraulic system, and associated electronic device. The invention relates to a method for evaluating the remaining service life of a component in a hydraulic system, the method being implemented iteratively on k=1..K data portions and comprising: a determination, for a data portion k, of a value representing damage to the component since an initial instant, said value being determined based on a value representing partial damage determined for portion k and based on a value representing damage determined for a portion k-1 of said data; and an evaluation, for portion k, of a relative remaining service life of the component, based on the value representing damage to the first component since an initial instant. Figure for the abstract: Fig. 1.

Description

Title of the invention: Method for evaluating the remaining service life of a component in a hydraulic system, and associated electronic device. Technical field

[0001] The present invention belongs to the general field of hydraulic systems. More particularly, it relates to a method for evaluating the remaining service life of a rotating relative load component of a hydraulic system. It also relates to a method for evaluating the remaining service life of a component of a hydraulic system subjected to a repeated or alternating load without relative movement with respect to the stressed component. Finally, it relates to an overall method for evaluating the remaining service life of a hydraulic system, and an electronic device configured to implement one of the evaluation methods mentioned above. Prior art

[0002] A hydraulic system is composed of components which present a risk to operators, particularly when it is supplied by a high-pressure fluid.

[0003] The main causes of accidents involving pressurized hydraulic fluids are classically linked to a lack of maintenance which can then lead to leaks of pressurized fluid following a sealing defect, but also to a breakage of a component or part of the system.

[0004] Also, such a system requires specific maintenance methods which aim to maintain the system in its intended function, without damage to itself and / or to the environment in which it is located, but also to guarantee the safety of its operation.

[0005] To this end, so-called "predictive" maintenance aims to anticipate the occurrence of a failure and to be able to plan a maintenance schedule. To do this, the condition and operating level of the system's components are assessed, and a remaining useful life (RUL) before a failure occurs is determined. In this way, it is possible to schedule the appropriate maintenance operations at the most opportune time, and in particular before a failure occurs.

[0006] However, the methods for evaluating residual life implemented so far require acquiring and storing a large amount of raw data before being analyzed, and are therefore not suitable for implementation "on the fly". Description of the invention

[0007] The present invention aims to remedy all or part of the disadvantages of the prior art, in particular those set out above, by proposing a solution which makes it possible to determine a residual life of a part of a hydraulic system or more generally of the hydraulic system, without it being necessary to store and access a large amount of raw data.

[0008] To this end, and according to a first aspect, the invention relates to a method for evaluating the remaining service life of a part, referred to as the "first part", of a hydraulic system, the first part being subject to a rotating relative load, the method being implemented iteratively on k = kK portions of data representing the pressure of a fluid within the hydraulic system and data representing the rotational speeds of said hydraulic system, by an electronic device and comprising:

[0009] - a determination, for a portion k of data, of a representative value of damage to the first part from an initial instant, said value being determined based on a representative value of partial damage determined for portion k and based on a representative value of damage determined for a portion k-1 of said data; and,

[0010] - an evaluation, for portion k, of a residual lifespan of the first piece, depending on the representative value of damage to the first piece since the original moment.

[0011] Thus, advantageously, to determine the remaining lifespan of the first part at iteration k, only the representative value of partial damage determined during this iteration k (for portion k) and the representative value of damage determined for portion k-1 of said data need to be accessible. This portion k-1 immediately precedes (in time) portion k, which corresponds to the current portion considered for evaluating a remaining lifespan.

[0012] As discussed in more detail below, the value determined "for the portion k-1" covers the case of a value determined at iteration k-1 for this portion of index k-1, but also that of a value determined at iteration k-1 for and / or as a function of each of the portions of index 1-k-1 considered from an origin time.

[0013] Each data portion k corresponds to a set of data captured over a predetermined and constant period of time, and these data portions define a certain frequency for evaluating the remaining lifespan of a component of the system. In other words, the evaluation process is applied to packets of records of finite and constant length.

[0014] This "first part" can be, for example, a cam, a roller, or a bearing.

[0015] The "rotating relative load" corresponds, for example, to the radial load on a shaft rotating in rotary bending, to the equivalent radial load on the cage or the balls of a bearing, or to the reaction forces of cams on the rollers of a radial technology hydraulic motor.

[0016] The origin moment mentioned above corresponds, for example, to a first use of the part whose remaining life is being evaluated, or to the first commissioning of the hydraulic system.

[0017] The process mentioned above is, for example, implemented until a stopping condition is reached. This stopping condition corresponds, for example, to a remaining service life below a predetermined threshold, or to the detection of cracks or breakage of said part.

[0018] In particular embodiments, the parts for which a residual life is evaluated correspond to an Inverse Power life model, for example the Basquin model.

[0019] This feature is advantageous in that these models make it possible to associate an equivalent number of cycles with an equivalent constraint.

[0020] In general, it is considered that the steps of a process should not be interpreted as being linked to a notion of temporal succession.

[0021] In particular modes of implementation, the evaluation process may further include one or more of the following characteristics, taken individually or in all technically possible combinations.

[0022] In particular embodiments, the steps of this process are iterated for each of the rotating relative load parts of the hydraulic system, and the most unfavorable remaining life is considered.

[0023] As is known, the components of a hydraulic system can be subjected to several "modes of damage." For example, it is common to observe degradation of these components through fatigue resulting from the application of forces, through contact fatigue with a viscous substance such as oil, or through a combination of these different fatigues. Damage modes due to adhesive or abrasive wear can also be considered, provided that the wear or friction coefficients are known.

[0024] Also, in particular embodiments, the steps of this process are iterated for each of the modes of damage of a first part of the hydraulic system, and the most unfavorable remaining life is considered.

[0025] In particular embodiments, the method further includes a determination of the representative value of partial damage for the portion k.

[0026] In particular embodiments, the representative value of damage to the first part from an origin time corresponds to a normalized pseudo-damage determined from the origin time.

[0027] Equivalently, this value representing damage to the first part from an initial instant corresponds to an average of the values ​​representing partial damage determined for each of the k portions.

[0028] In particular embodiments, the representative value of damage to the first part from an origin time is a function of a sum of A: -1 representative values ​​of damage from an origin time and determined for each of the A -1 portions treated prior to portion k.

[0029] In particular implementation modes, the evaluation process further includes:

[0030] - a determination of a number of operating quadrants to be considered, according to that the hydraulic system is supplied by a fluid having one or more pressure levels, and / or depending on whether the velocity data are signed or not,

[0031] said value representing damage to the part from an original instant being determined for each of said quadrants,

[0032] The evaluation, for portion A, of a residual life of the first part includes an evaluation of a relative residual life associated with each of said quadrants; and the evaluation of the residual life of the first part is further implemented as a function of the relative residual lives associated with said quadrants.

[0033] In particular embodiments, the hydraulic system comprises a multilobe cam comprising half-lobes, the system being alternately supplied by a fluid under high pressure and under low pressure, and the method further comprises a distribution of said data according to the half-lobes undergoing high pressure and the half-lobes undergoing low pressure;

[0034] and the determination of a residual life of the first part is further implemented by distinguishing each of said half-lobes.

[0035] In particular embodiments, the remaining life of the first part corresponds to a value selected from the relative remaining lives and less than a predetermined threshold, or to the minimum relative remaining life.

[0036] According to a second aspect, the invention relates to a method for evaluating the remaining service life of a part, referred to as the "second part", of a hydraulic system subjected to a repeated or alternating load without relative movement with respect to said part, the method being implemented iteratively on Jç = K Pordons of representative data of loads exerted on the second part:

[0037] - a determination, for a portion £' of data, of damaging cycles by application of a cycle counting method;

[0038] - a determination, for the portion £' of data, of a representative value of a damage to the second part from an initial instant, said value being determined based on a result of applying the cycle counting method, a representative value of partial damage determined for portion £' and a representative value of damage determined for a portion £' _ J of said data; and,

[0039] - an evaluation, for the portion £', of a relative residual life as a function of the representative value of damage to the second part from an original instant.

[0040] Thus, advantageously, at iteration fa, only the representative value of a partial damage determined during that iteration (for portion £') and the representative value of a damage determined for portion £_ of said data should be accessible. This portion £-1 immediately precedes (in time) the portion £r, which corresponds to the current portion considered for evaluating a remaining lifetime.

[0041] As discussed in more detail below, the value determined "for the portion £' _ covers the case of a value determined at iteration £ _ 1 for this portion of index £*_ J, but also that of a value determined at iteration £ -1 for and / or as a function of each of the portions of index 1 £ _ j considered from an origin time.

[0042] Each data portion £' corresponds to a set of data captured over a predetermined period of time, and these data portions define a certain frequency for evaluating the remaining lifespan of a component of the system. Thus, the evaluation process is applied to packets of records of finite and constant length.

[0043] This second part can be, for example, a shaft, a shaft spline, an enclosure or a housing subjected to pressure.

[0044] The origin moment mentioned above corresponds, for example, to the first use of the part whose remaining life is being evaluated, or to the first commissioning of the hydraulic system.

[0045] The process mentioned above is, for example, implemented until a stopping condition is reached. This stopping condition corresponds, for example, to a remaining service life below a predetermined threshold, or to the detection of cracks or breakage of said part.

[0046] In particular embodiments, the parts for which a residual life is evaluated correspond to an Inverse Power life model, for example the Basquin model.

[0047] This feature is advantageous in that these models make it possible to associate an equivalent number of cycles with an equivalent constraint.

[0048] In particular embodiments, the cycle counting method applied corresponds to the cascading extent counting method, also called "Rainflow Counting", and for example described in the article "Fatigue of metals subjected to varying stress", M. Matsuichi and Tsutomu Endo, published in 1968.

[0049] In particular embodiments, the cascade extent counting method applied conforms to the AFNOR A03-406 standard, "Metallic products - Fatigue under variable amplitude stresses - Rainflow method of cycle counting", published in November 1993.

[0050] In particular embodiments, the representative value of a determined partial damage for portion k is determined by applying the Palmgren-Miner method or the Manson-Halford cumulative correction method. The Manson-Halford cumulative correction method is described, for example, in the article "Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction", Huang B, Wang S, Geng S, Liu X., published in February 2021 in Advances in Mechanical Engineering.

[0051] In particular embodiments, the representative value of damage to the second part from an origin time corresponds to normalized damage from the origin time or to an average of representative values ​​of normalized partial damage determined for each of the portions.

[0052] In particular embodiments, the representative value of damage to the second part from an original instant is a function of a sum of fa' _ representative values ​​of damage from an original instant and determined for each of the | portions.

[0053] In particular embodiments, the steps of this process are iterated for each of the parts of the hydraulic system, called "second parts", subjected to a repeated or alternating load without relative movement, and the most unfavorable remaining life is considered.

[0054] In particular embodiments, the steps of this process are iterated for each of the damage modes of a second part of the hydraulic system, and the most unfavorable remaining life is considered.

[0055] According to a third aspect, the invention relates to an overall method for evaluating the remaining service life of a hydraulic system comprising at least one part, referred to as the "first part", subjected to a rotating relative load, and at least one part, referred to as the "second part", subjected to a repeated or alternating load without relative movement with respect to said second part, the overall method comprising:

[0056] - an implementation, for at least a first part, of the evaluation process of a residual lifespan according to the first aspect;

[0057] - an implementation, for at least a second part, of the evaluation process of a residual lifespan according to the second aspect; and,

[0058] - a determination of the remaining service life of the hydraulic system as a function residual life periods associated with at least one first part and at least one second part.

[0059] According to a fourth aspect, the invention relates to a computer program comprising instructions for implementing an evaluation method according to the first, second, and / or third aspect, when said program is executed by a computer.

[0060] This program may use any programming language, and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0061] According to a fifth aspect, the invention relates to a computer-readable recording medium on which the computer program according to the invention is recorded.

[0062] The information or recording medium can be any entity or device capable of storing the program. For example, the medium can include a storage means, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a hard disk drive.

[0063] On the other hand, the information or recording medium can be a transmissible medium such as an electrical or optical signal, which can be transmitted via an electrical or optical cable, by radio, or by other means. The program according to the invention can, in particular, be downloaded onto an Internet-type network.

[0064] Alternatively, the information or recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the process in question.

[0065] According to a sixth aspect, the invention relates to an electronic device configured to implement an evaluation method according to the first aspect, an evaluation method according to the second aspect and / or an overall evaluation method according to the third aspect.

[0066] According to a seventh aspect, the invention relates to a residual life evaluation system comprising the electronic device according to the sixth aspect, and further comprising a hydraulic machine configured to operate alternately as a pump and as a hydraulic motor. Brief description of the drawings

[0067] Other features and advantages of the present invention will become apparent from the description below, with reference to the accompanying drawings, which illustrate an example of an embodiment without being limiting in any way. In the figures:

[0068] [Fig-1] [Fig.1] schematically represents an example of an evaluation system of a residual lifespan according to an example of implementation of the invention;

[0069] [Fig.2A] [Fig.2A] represents modules embedded in an evaluation device, such as the evaluation device belonging to the system of [Fig.1], according to a first example of implementation of the invention;

[0070] [Fig.2B] [Fig.2B] represents modules embedded in an evaluation device, such as the evaluation device belonging to the system of [Fig.1], according to a second example of implementation of the invention;

[0071] [Fig.2C] [Fig.2C] represents modules embedded in an evaluation device, such as the evaluation device belonging to the system of [Fig.1], according to a third example of implementation of the invention;

[0072] [Fig.3A] [Fig.3B] [Fig.3C] Figures 3A, 3B and 3C schematically represent examples of the hardware architecture of an evaluation device belonging to the evaluation system of [Fig.1];

[0073] [Fig.4] [Fig.4] represents, in the form of a flowchart, a particular method of implementing a method for evaluating the remaining life of a rotating relative load part of a hydraulic system, for example carried out by the evaluation device of [Fig.2A];

[0074] [Fig.5] [Fig.5] represents, in the form of a flowchart, a first example of the implementation of the method for evaluating the remaining life of a part with a rotating relative load in a hydraulic system;

[0075] [Fig.6] [Fig.6] represents, in the form of a flowchart, a second example of the implementation of the method for evaluating the remaining life of a part with a rotating relative load of a hydraulic system;

[0076] [Fig.7] [Fig.7] represents, in flowchart form, a particular method of implementing a process for evaluating the remaining service life of a part of a hydraulic system subjected to a repeated or alternating load without relative movement with respect to said part, for example carried out by the evaluation device of [Fig.2B]; and

[0077] [Fig. 8] [Fig. 8] schematically represents an example of the implementation of an overall method for evaluating the remaining service life of a hydraulic system, for example, carried out by the evaluation device in [Fig. 2C]. Description of embodiments

[0078] The terms "first" (or "first part"), "second" (or "second part"), etc., are used in this document by arbitrary convention to allow for the identification and distinction of different elements (such as components, mechanical parts, etc.) considered in the embodiments described below. Thus, unless otherwise stated, no notion of order should be associated with these terms.

[0079] Fig. 1 schematically represents an example of a residual life evaluation system, according to an example of implementation of the invention.

[0080] As illustrated in [Fig. 1], the system 1000 comprises a hydraulic machine 100 with radial pistons and a multilobe cam. This hydraulic machine 100 conforms, for example, to that described in patent document FR2846381B1 published on January 28, 2005. Alternatively, this hydraulic machine corresponds to the radial piston hydraulic motor described in patent document FR2892775B1 published on November 5, 2010.

[0081] The hydraulic machine 100 comprises a housing defining an internal volume in which a shaft extending along an axial direction ZZ and a cylinder block are positioned. The cylinder block comprises a plurality of housings in which pistons are mounted to slide radially with respect to the axial direction ZZ.

[0082] The hydraulic machine 100 also includes a multilobe cam positioned around the cylinder block. The cam defines a plurality of lobes adapted to cooperate with the pistons during the operation of the hydraulic machine 100. The cylinder block is coupled to a distributor defining fluid supply and discharge channels connected to the various housings in which the pistons slide. These channels are also referred to as "supply ports" in the remainder of this description.

[0083] For the hydraulic machine 100, a first assembly comprising the cylinder block is defined, and a second assembly comprising the housing and the cam. The first and second assemblies are movable relative to each other in rotation along the axial direction ZZ, one of these assemblies being fixed and the other movable depending on the application considered.

[0084] The hydraulic machine 100 is typically reversible. It can operate as a hydraulic pump (the system converts mechanical energy into hydraulic energy) or alternatively as a hydraulic motor (the system converts

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[0091] hydraulic energy into mechanical energy) depending on its use, the operation of such a hydraulic machine 100 being otherwise well known. It should be noted, however, that considering a hydraulic machine is only one variant of the invention's implementation. Generally speaking, there are no limitations attached to the hydraulic system considered, which may consist of a hydraulic pump, a hydraulic motor, or a hydraulic machine that, as mentioned above, may operate as a hydraulic pump or a hydraulic motor. The 1000 evaluation system further includes an electronic device 10-1, 10-2, 10-3 for evaluating the remaining service life of at least one part of the hydraulic machine 100. As illustrated in [Fig. 1], the evaluation device 10-1, 10-2, 10-3 is connected to a rotational speed sensor 30 of the hydraulic machine 100. The evaluation device 10-1, 10-2, 10-3 is also connected to hydraulic pressure sensors 20-1, 20-2 configured to transmit representative pressure data of a fluid circulating within the hydraulic machine 100 to the evaluation device 10-1, 10-2, 10-3. These sensors 20-1, 20-2 allow, for example, the recording of fluid pressures at the fluid supply and discharge lines. The sensors 20-1, 20-2, and 30 can be directly connected to the evaluation device via a wired or wireless connection, or via a telecommunications network (not shown). Fig. 2A represents modules embedded in a 10-1 evaluation device, such as the evaluation device belonging to system 1000 of Fig. 1, according to a first example of implementation of the invention. As illustrated in [Fig. 2A], the 10-1 evaluation device includes, in particular: - a MOD_DET_P1 module for determining, for a portion k of data, a pppqDAç[kj] value representative of damage to a part of the hydraulic machine 100, called the "first part," from an initial instant Tq, this first part being under a rotating relative load, said value j^PD DAq [k] being determined as a function of a value N PD q (k), DPQ.(k) representing a partial damage determined for portion k and as a function of a value ]\JPDF Oç[k DAq [k - ij] representing a damage determined for a portion k -1 of the data; and - a MOD_EVAL_P1 evaluation module, for this portion k, of the remaining lifespan of the first part, depending on the value NPDFOQ[k] DAQ[k] representative of damage to the first part from the original moment Tq.

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[0102] This first part could be, for example, a cam, a roller, or a bearing. The relative rotating load corresponds, for example, to the radial load on a shaft rotating under rotational bending, the equivalent radial load on the cage or balls of a bearing, or the reaction forces of cams on the rollers of an engine. radial technology hydraulics. Fig. 2B represents modules embedded in a 10-2 evaluation device, such as the evaluation device belonging to system 1000 of Fig. 1, according to a second example of implementation of the invention. As illustrated by [Fig.2B], the 10-2 evaluation device includes in particular: - a MOD_DET_CL module for determining, for a portion £' of data, damaging cycles by applying a cycle counting method; - a MOD_DET_P2 module for determining, for this portion of data, a value FlDFO^k^ DAg(k^) representative of damage to a part of the hydraulic machine 100, called the "second part," from an initial instant Tq, this second part being subjected to a repeated or alternating load without relative movement with respect to said second part, said value NUFOg^k^ DAg[k] being determined as a function of a value representative of damage partial determined for portion F and as a function of a value NDFOg[k- 1)' DA^k - 1) representative of a damage determined for a portion F of said data; and - a MOD_EVAL_P2 evaluation module, for this portion of a relative residual life (RU Lg[k^ of the second part, as a function of the value (NDFOg^k )' DAg(k )) representative of damage to the second part since the original instant Tq. This second part can be, for example, a shaft, a shaft spline, an enclosure or a housing subjected to pressure. Fig. 2C represents modules embedded in a 10-3 evaluation device, such as the evaluation device belonging to system 1000 of Fig. 1, according to a third example of implementation of the invention. As illustrated by [Fig.2C], the 10-3 assessment device includes the modules described with reference to Figures 2A and 2B. Fig. 3A schematically represents an example of the hardware architecture of an assessment device, such as the 10-1 assessment device in Fig. 2A.

[0103] As illustrated by [Fig. 3A], the 10-1 evaluation device has the hardware architecture of a computer. Thus, the 10-1 evaluation device includes, in particular, a processor 1, random access memory 2, read-only memory 3 and non-volatile memory 4. It also has communication means 5.

[0104] The read-only memory 3 of the evaluation device 10-1 constitutes a storage medium according to the invention, readable by the processor 1, on which is stored a computer program PROG_P1 conforming to one aspect of the invention, comprising instructions for executing steps in the process of evaluating a part under rotating relative load. The PROG_P1 program defines functional modules of the evaluation device 10-1, which rely on or control the hardware elements 1 to 5 of the evaluation device 10-1 mentioned above. These functional modules are illustrated in [Fig. 2A] by way of no limitation, and are described in more detail below with reference to different embodiments.

[0105] The communication means 5 enable the evaluation device 10-1 to exchange data with any equipment of the system 1000, including in particular the sensors 20-1, 20-2 and 30. For this purpose, the communication means 5 include a communication interface, wired or wireless, capable of implementing any suitable protocol known to a person skilled in the art.

[0106] Fig. 3B schematically represents an example of the hardware architecture of an evaluation device, such as the 10-2 evaluation device of Fig. 2B.

[0107] As illustrated by [Fig.3B], the 10-2 evaluation device also has the hardware architecture of a computer, and differs from the 10-1 evaluation device in that the read-only memory 3 of the 10-2 evaluation device constitutes a recording medium on which is recorded a computer program PROG_P2 conforming to one aspect of the invention, comprising instructions for the execution of steps of the process of evaluating a part subjected to a repeated or alternating load without relative movement with respect to that part.

[0108] Fig. 3C schematically represents an example of the hardware architecture of an evaluation device, such as the 10-3 evaluation device of Fig. 2C.

[0109] As illustrated by [Fig.3C], the 10-3 evaluation device also has the hardware architecture of a computer, and differs from the 10-1 and 10-2 evaluation devices in that the read-only memory 3 of the 10-3 evaluation device constitutes a recording medium on which is recorded a computer program PROG_SYS conforming to one aspect of the invention, comprising instructions for the execution of steps of the overall method of evaluating the remaining life of a hydraulic system comprising at least one first rotating relative load part and at least one second part subjected to a repeated or alternating load without relative movement with respect to said second part.

[0110] Figure 4 represents, in flowchart form, a particular method of implementation work of a method for evaluating the remaining life of a rotating relative load part of a hydraulic system - called first part -, for example carried out by the evaluation device 10-1 of figures 2A and 3A.

[0111] As mentioned previously, the parts for which a residual life is evaluated correspond to an Inverse Power Life model, for example the Basquin model. An Inverse Power Life model makes it possible to associate an equivalent number of cycles with an equivalent stress.

[0112] More formally, a Basquin model is expressed as follows:

[0113] x na = ab x nb = Constant.

[0114] with A and B two points respectively defined by the coordinates (N<7^) and (NB; Œp), (7^ and o~B of the values ​​of the amplitude of an applied stress, and NA and NB of the values ​​of a number of cycles.

[0115] However, analyses carried out on the one hand between the stress with respect to the number of cycles, and on the other hand between the load and the number of cycles, can give different Basquin slopes (i.e., slopes of the line (AB)).

[0116] Therefore, prior knowledge of the Basquin slope for a given part is necessary to implement this evaluation method.

[0117] As illustrated by Figure 4, the method for evaluating the remaining life of a part under rotating relative load includes a first step S0 during which a portion k of data representative of the pressure of a fluid within the hydraulic system and of data representative of the rotational speeds of said hydraulic system is obtained.

[0118] The hydraulic system under consideration corresponds, for example, to the hydraulic machine 100, and the fluid pressure data are received, for example, from sensors 20-1, 20-2 which record the fluid pressures at the level of the fluid supply and discharge lines. Furthermore, the representative rotational speed data correspond, for example, to the rotational speeds of the first or second assembly along the axial direction ZZ captured by the rotational speed sensor 30 of the hydraulic machine 100.

[0119] The method further includes a step S100 in which a number of operating quadrants to be considered is determined.

[0120] The four operating quadrants of a hydraulic machine are conventionally defined as follows: quadrant Q1 corresponds to the case where the torque and speed are positive, and the machine then operates as a hydraulic motor; quadrant Q2 corresponds to the case where the torque is positive and the speed is negative, and the machine then operates as a hydraulic pump; quadrant Q3 corresponds In the case where the torque and speed are negative, the machine then operates as a hydraulic motor; and quadrant Q4 corresponds to the case where the torque is negative and the speed is positive, and the machine then operates as a hydraulic pump. Depending on the operating quadrants considered, the forces, positions, and contact areas of the rollers, pistons, and bearings on the cam, shafts, splines, and keys change locally. For example, depending on the direction of torque application, the splines of the splined shafts or cylinder blocks will be stressed on one face or the other. Depending on the direction of rotation and the direction of the applied torque, the cams will be subjected to high pressure on either an upward or downward lobe.

[0121] When the hydraulic machine is supplied with a fluid that can have several pressure levels - typically high and low pressure from an open or closed loop circuit - at least two quadrants must be considered, for example the quadrant pair (Q1, Q4) or the pair (Q2, Q3).

[0122] Moreover, when the data representing the speed are signed (i.e., when they are positive or negative), it is possible to distinguish the case where the hydraulic machine operates as a motor (quadrants Q1 and Q3) from the case where the hydraulic machine operates as a pump (quadrants Q2 and Q4), and thus to refine the damage and wear zones of the rollers, pistons and supports.

[0123] Thus, when the data obtained are representative of high and low fluid pressures and the data representative of rotational speeds are signed, the evaluation of a lifetime can be implemented by distinguishing each of the four quadrants.

[0124] By distinguishing each of the quadrants, the evaluation process makes it possible to "redistribute" the damage more fairly, according to each of the operating quadrants.

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[0127] The process for evaluating a remaining service life further includes a step S110 in which the data obtained in step S0 are segmented according to the operating quadrants determined in step S100. The process further includes steps S120, S130, and S140, which are implemented for each of the quadrants determined in step S100. Step S120 corresponds to the determination of an NP Dq(k) value, representative of a partial damage to portion k. During an S130 step, a value jjpDAç[kj] representing damage to the first part from an initial time Tq is determined for the portion k of the data obtained. This S130 step is implemented, for example, by the MOD_DET_P1 module of the 10-1 evaluation device. This value

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[0132] MPDFOQ^k^ DAç[kj is determined based on the value NPDQ.(k) , DPç^kj determined in step S120, and based on the value jyPJJPOç^k lj' DAç^k- ij representative of damage determined for a portion k-1. As mentioned above, this portion k-1 immediately precedes (in time) the portion k which corresponds to the current portion considered to evaluate a remaining life. During step S140, a relative remaining life (jj of the first part, is evaluated based on the value PJPDPQq DAQ^kj representing damage determined in step S130. This step S140 is for example implemented by the MOD_EVAL_P1 module of the evaluation device 10-1. The evaluation process further includes a step S150 in which it is determined whether the data associated with each of the Q quadrants determined in step S100 have been processed. If not (choice "N"), steps S120 to S140 are repeated. If, on the other hand, the data associated with each of the Q quadrants have been processed (choice "Y"), a step S160 is implemented in which a residual life pUL{k) of the first part is evaluated based on the relative residual lives PUPqI associated with each of the quadrants. According to a particular implementation method, the remaining service life (pUL^k) of the part corresponds to a value selected from the relative remaining service lives (pypQ^pj) that is less than a predetermined threshold. Alternatively, the remaining service life of the part corresponds to the worst-case scenario, i.e., the minimum relative remaining service life. As mentioned previously, an initial dichotomy is implemented during step S110 based on operating quadrants. According to other implementation methods, this initial dichotomy is further refined based on specific elements of the part or component, such as lobes, bearings, etc. In one particular case, the component is a radial piston driven by a multi-lobe cam comprising half-lobes, and the hydraulic system is alternately supplied with high-pressure and low-pressure fluid. When high pressure is applied to the main supply port of the radial piston hydraulic receiver, some cam lobes experience high-pressure stresses, while others experience only low-pressure stresses. low pressure (LP). In this particular case, the evaluation process includes a further dichotomy according to the hemi-lobes subjected to high pressure and the hemi-lobes subjected to low pressure. Furthermore, the value NPDFÛQ^k) Representing damage from the first room since a The original instant Tq determined in step S130 is determined for each of the half- lobes; the evaluation, for portion k, of a residual lifespan ( RULQ^kf of the first part includes an assessment of a relative remaining service life associated with each of said hemi-lobes; and the assessment of the remaining service life of the first part is also implemented according to the relative residual life periods associated with said half-lobes.

[0133] Alternatively, the first part is an axial piston or an axial piston component, and a similar method is implemented.

[0134] According to a particular embodiment, only the residual lifetime RUL(k) of the first part is saved, for example in the non-volatile memory 4 of the device-1, 10-2, 10-3. Alternatively, some or even all of the relative residual lifetimes of the first part are saved (e.g., the lifetimes associated with each quadrant, the lifetimes associated with each half-lobe, etc.).

[0135] The invention has so far been described in the particular case where the part is subjected to a single mode of damage in. The invention remains applicable in the case where the part is subjected to several (M) modes of damage, for example by the application of forces on this part and by contact with a viscous body.

[0136] This aspect of the invention has also been described so far in the specific case where a single first part P is considered. The invention nevertheless remains applicable in the case where several first parts are considered.

[0137] Figure 5 represents, in the form of a flowchart, a first example of the implementation of the method for evaluating the remaining service life of a rotating relative load part of a hydraulic system.

[0138] Prior knowledge of the pressure-stress transfer function is required. Furthermore, it is subsequently assumed that the load-stress relationship is linear or log-linear. Otherwise, the Basquin model is applied directly to the stress.

[0139] As illustrated in Figure 5, the evaluation process comprises a first step §CONF during which an origin time Tq, a duration SEQL of a portion, a reference pressure Pppp, a reference rotational speed Sppp, a

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] reference lifetime (RLEF), and a normalized reference pseudo-damage — pbv Ç are defined, with b a slope of the Basquin model, ^^REF — rREF ^^REF F for example equal to 3 or in the context of bearings. The process further includes steps S100 and SI10 previously described with reference to Figure 4. The process also includes a step S520, which is an example of an implementation of step S120 mentioned with reference to Figure 4. In this example, the representative value of partial damage for portion k corresponds to a normalized pseudo-damage NPDq(k). This normalized pseudo-damage is expressed, for example, as follows: AVERAGE [p(t)bX sMxQ(tl) NPDq (k) = 1 u t=LTk with P(t) a pressure value at time t, S(t) a rotational speed value at that time t, being equal to "0" if the quadrant does not match to the one in operation at time t, and being equal to "1" if the quadrant Q. corresponds to the one in operation at time t, and T k the last time t of the data portion k. The process also includes a step S530, which is an example of the implementation of step S130 mentioned with reference to Figure 4. In this example, the value NP DF Oq(k) representing damage to the part since the initial time Tq is expressed as follows: NPDF0Q.(k) = Alternatively, NPDQ^kyRk-Dx NPDFOç^k-ï) , T , AVERAGE {nPDq (k)} NPDFOQ;(k)= 1 ' The process also includes a step S540, which is an example of the implementation of step S140 mentioned with reference to Figure 4. In this example, the relative remaining life of the first part is evaluated as follows: RULQ(k') = LREFx NPDrep NPDFOQ(k) -kxSEQL with SEQL the duration of a portion. Thus, during iteration k, this process only requires access to the following values: the partial damage for the portion k obtained at iteration k, the pseudo normalized damage from origin N PDF Oq ( k- 1 ) obtained at iteration k-1, the iteration value k, and the reference values ​​Prpf, V reF' ^ref previously mentioned.

[0150] In addition, it is important to note that the use of an iterative approach is advantageous in that it avoids storing large signals.

[0151] Figure 6 represents, in the form of a flowchart, a second example of the implementation of the method for evaluating the remaining service life of a rotating relative load part of a hydraulic system.

[0152] As before, prior knowledge of the transfer function between the load and the stress or the damage variable is required. Furthermore, it is subsequently assumed that the relationship between the load and the stress is linear, or log-linear. Otherwise, the Basquin model is applied directly to the stress.

[0153]

[0154] As illustrated by Figure 6, the evaluation process includes a first step SCoNF during which an origin time Tq, a duration SEQL of a portion, a reference pressure P ref^ a reference rotation speed VreF' a reference lifetime Lppp, and RE V ref a number of reference revolutions or cycles before failure such that REV REp = SRef X LRef are defined. The process further includes steps S100 and S10 previously described with reference to Figure 4. The process also includes a step S610 for calculating the following quantities, for each quadrant: qfg |1 2 3 4^

[0155] - an effective average pressure

[0156] RMEPq} k i AVERAGE^tfx s(t)xQ$) t=ETk AVERAGE(s(t)xQ^) t=ETk Vb

[0157]

[0158]

[0159] - a weighted average speed f=1 T WASq (k)=-------¾.....-t...... v AVERAGE^p:)) t=l.Tk - a proportion PROPq. ( k ) of time spent in quadrant Q. such that proPqW = AVERAGE^ t=l.Tk

[0160] The process also includes a step S620 which is an example of Implementation of step S120 mentioned with reference to Figure 4. In this example, the representative value of partial damage for portion k is expressed by For example, as follows:

[0161] DPQi(k) = WASQ^k) x PROPQ[k] x SEQL ■P REF RMEP^k) fi | x REVrep DA) of the first piece is then expressed, for example, as follows:

[0162] Then a step S630 is implemented which corresponds to an example of the implementation of step S130 mentioned with reference to Figure 4. In this example, the value DAq.(k) representing cumulative damage to the first part since an initial instant Tq is expressed as follows:

[0163] DAQ.(k) = DAç.(k-1) +DPo.(k)

[0164] The process further includes a step S640 which corresponds to an example of implementation of step S140 mentioned in reference to [Fig.4].

[0165] When the Palmgren-Miner damage accumulation method is applied (by summing the results obtained in previous iterations), the relative residual life 101661 RULQ.(k) =MINIMUM(l-DAQ.(k)]xl00

[0167] In this particular case, the result provided is expressed as a percentage, but a duration (for example in hours, minutes, seconds) could alternatively be considered.

[0168] As is known per se, for parts subjected to Inverse Power laws, the Palmgren-Miner damage accumulation law accounts for the total damage sustained by these parts. The potential lifetime for a fixed load / stress is given by the Basquin model. According to the Palmgren-Miner method, the Damage DA is:

[0169] nA = ^1 ■ ^2 । ■ Ep _^occurrences ^2 NP ^occurrences=l^ occurrences

[0170] with occurrences; the number of cycles performed for a constant stress amplitude, and occurrences; the number of cycles that can be performed under a constant stress amplitude, for a predetermined permissible failure rate (for example, 10%). The Palmgren-Miner cumulative damage value is then between 0 and 1, "0" corresponding to a new part and "1" in the case where the predetermined permissible failure rate is reached.

[0171] Figure 7 represents, in flowchart form, a particular method of implementation implementation of a method for evaluating the remaining service life of a part – referred to as the second part – of a hydraulic system subjected to repeated or alternating load without relative movement with respect to the stressed / loaded part. This process is for example carried out by the evaluation device of [Fig.2B].

[0172] This second part can correspond to any part whose load is not rotating relative to the loaded / stressed part, for example a supply port, a shaft, a valve, a hydraulic distributor, a shaft in alternating bending.

[0173] Thus, this second part does not, for example, suffer damage or wear caused by rotation relative to a fixed reference frame.

[0174] As illustrated by Figure 7, the method for evaluating the remaining life of a second part includes a first step S0 during which a portion of data representative of repeated or alternating loads is obtained.

[0175] The hydraulic system considered corresponds for example to the hydraulic machine 100, and the data obtained are received from sensors installed on this hydraulic machine 100.

[0176] The process further includes a step S200 in which damaging cycles are determined by applying a cycle counting method. This step S200 is implemented, for example, by the MOD_DET_CL module of the 10-2 evaluation device.

[0177] The cycle counting method applied corresponds to the cascading extent counting method, also called "Rainflow Counting", and for example described in the article "Fatigue of metals subjected to varying stress", M. Matsuichi and TsutomuEndo, 1968.

[0178] In particular modes of implementation, the cascading extent counting method is for example in accordance with the AFNOR A03-406 standard, "Metallic products - Fatigue under variable amplitude stresses - Rainflow method of cycle counting", published in November 1993.

[0179] More precisely, to implement the cascading extent counting method, an analysis periodicity is predetermined and linked to the duration of the data portions considered during each iteration fa. In addition, a condition also determines whether the cascading extent counting should be implemented with or without closing the residuals.

[0180] This condition relates to a periodicity of closing the residues. As long as the condition is not met, the process iterates by extracting the residues from the current count, then concatenating them to the front of the next portion. Then, when the condition is met, the residues are closed during the count.

[0181] The method further includes a step S210 in which a representative value of partial cumulative damage is determined for

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[0183]

[0184]

[0185]

[0186]

[0187]

[0188] the portion £ depending on a result from the implementation of the cycle counting method In other words, for each count, damage accumulates, whether the residuals are closed or not. If the residuals are not closed, then the damage accumulated over the duration of the portion is locally lower, but the overall result is corrected when the residuals are closed, since the residual is saved and then concatenated before the next data portion (of the first iteration), and this is done iteratively. Thus, the Rainflow count of the k+l-th portion is obtained by concatenating the residual of the k-th count. Applying the Palmgren-Miner damage accumulation method over the duration of the portion, the value DP^k is then expressed in the form: DPff{ k ) — . f, , fv 1 y \ ç{RainflowClass):g\ ) g with i a two-dimensional variable defining a position in a Rainflow outcome matrix - such as a position [amplitude, mean] in a 3D Rainflow matrix [amplitude, mean, number of cycles] -, Ri a number of damaging cycles performed and N a number of achievable damaging cycles. The use of the Palmgren-Miner damage accumulation method is only one non-limiting example, and other methods can also be considered, such as the Manson Halford correction accumulation method which takes into account the loading history and for example described in the article "Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction", Huang B, Wang S, Geng S, Liu X., published in February 2021 in Advances in Mechanical Engineering. Then, during an S220 step, a DA^k^ value representative of a The damage to the second part from an initial instant Tq is determined. This step S220 is, for example, implemented by the MOD_DET_P2 module of the 10-2 evaluation device. This value NDFOg^k^ DAg(k) is determined based on the value DPg(k) representing partial damage determined for the portion (determined in step S210) and based on a value NDFO^k-1)' DAg[k - 1) representing cumulative damage determined for a portion k -1 of said data. The process further includes a step S230 in which a relative residual life P{J]_^k^ is determined as a function of the value FlDFOg^k^ DA^k') representative of damage determined in step S220. This step S230 is for example implemented by the MOD_EVAL_P3 module of the 10-2 assessment device.

[0189] According to a first embodiment, the remaining life of the second part is calculated in hours, minutes, and seconds. In this case, the process includes, following step S210, a step (not referenced) in which a normalized damage k is determined for the portion Σ for each part. This normalized damage J\TD is expressed, for example, in the form / -x DP^), NDg[k] = SEqL

[0190] with SEQL a duration of portion k •

[0191] According to this first implementation example, the value NDFOç^k^ representing damage to the second part from an initial instant Tq determined in step S220 is then expressed in the form:

[0192] (-x NDg(kW-l)x NDFO / k'-Ü NPDFOa\k ) =—;-----75------- - k

[0193] Alternatively, this value is calculated as an average of normalized damages and is then expressed as follows: NDFn - AVERAGE (NDg(k)) 1\ Dr U al K j — J t=LTQ

[0194] Finally, still according to this first implementation example, the relative residual life p_[J]_^k^ of the part & determined in step S230 is then expressed, for example, as follows: [01951 mlkE^-k'xSEQL

[0196] According to a second embodiment example, the remaining life of the second part is calculated in the form of a percentage of remaining life.

[0197] In this particular case, when the Palmgren-Miner damage accumulation method is applied to each of the second parts, the value DA^k^ representing cumulative damage to the second part from an initial instant Tq (determined in step S220) is expressed as follows:

[0198] DAg(k) = DAg(kl) + DP^k)

[0199] Finally, still according to this second implementation example, the relative remaining service life of the part determined in step S230 is then expressed as for example such as:

[0200] RUL^k^l-DAg[k)) x 100-

[0201] This aspect of the invention has so far been described in the specific case where a single second part is considered. The invention nevertheless remains applicable in the case where several second parts are considered.

[0202] As mentioned previously, the invention also relates to an overall method for evaluating the remaining service life of a hydraulic system comprising a first rotating relative load component and a second component subjected to a repeated or alternating load without relative movement with respect to said second component. This method is, for example, performed by the evaluation device in [Fig. 2C] and comprises:

[0203] - an implementation, for the first part, of the evaluation method with a duration of residual life as illustrated by one of figures 4, 5 or 6;

[0204] - an implementation, for the second part, of the evaluation method with a duration of residual life as illustrated by [Fig. 7]; and,

[0205] - a determination of the remaining service life of the hydraulic system as a function residual lifespans associated with the first and second parts.

[0206] This aspect of the invention has so far been described in the specific case where a single first part and a single second part are considered. The invention nevertheless remains applicable in the case where several first and second parts are considered.

[0207] Figure 8 represents, in schematic form, an example of the implementation of an overall process for evaluating the remaining service life of a hydraulic system.

[0208] This figure illustrates more specifically the case of a hydraulic system comprising two parts P^ and P^ with rotating relative load, and three parts ff p ff? and subjected to a fixed relative repeated or alternating load, part P^ is subjected to two modes of damage ^1 and 7¾ and part P2 is also subjected to two modes of damage 7¾ and 7¾.

[0209] As illustrated by [Fig.8], the overall process is implemented iteratively for this hydraulic system and therefore comprises:

[0210] - an implementation, for part P^ subjected to damage mode ^i, of the method for evaluating a residual life as illustrated by one of figures 4, 5 or 6 in order to obtain a first residual life, this method being referenced "PROC1" in [Fig.8];

[0211] - an implementation, for part P^ subjected to damage mode m2, of the "PROC1" evaluation process so as to obtain a second residual lifespan;

[0212] - an implementation, for part P2-, of the evaluation procedure "PROC1" so as to to obtain a third residual lifespan;

[0213] - an implementation, for part Q of the method for evaluating a service life residual as illustrated by [Fig.7] so as to obtain a fourth residual life, this process being referenced "PROC2" in [Fig.8];

[0214] - an implementation, for part Q2 subjected to damage mode ^3, of the method for evaluating a residual life as illustrated by [Fig.7] so as to obtain a fifth residual life, this method being referenced "PROC2" in [Fig.8];

[0215] - an implementation, for the part subjected to damage mode m4, of the evaluation method "PROC2" so as to obtain a sixth residual lifespan; and

[0216] - an implementation, for part 6L, of the "PROC2" evaluation process so as to to obtain a seventh residual lifespan.

[0217] The method further includes a step S800 for determining the remaining service life of the hydraulic system, based on the first, second, ..., seventh remaining service lives. According to a particular embodiment, the remaining service life of the hydraulic system corresponds to a value selected from among the first, second, ..., seventh remaining service lives that is less than a predetermined threshold. Alternatively, the remaining service life of the hydraulic system corresponds to the worst-case scenario, i.e., to the minimum remaining service life of the first, second, ..., seventh remaining service lives.

Claims

Demands

1. A method for evaluating the remaining life of a part, called the "first part", of a hydraulic system, the first part being under rotating relative load, the method being implemented iteratively on k = LK portions of data representing the pressure of a fluid within the hydraulic system and data representing the rotational speeds of said hydraulic system, the representative pressure data corresponding to measurements captured by a pressure sensor of the hydraulic system, the representative rotational speed data corresponding to measurements captured by a rotational speed sensor of the hydraulic system, the method being implemented by an electronic device (10) and comprising: • a determination (S 130), for a portion k of data, of a value ^pj'ppp p^^j) of damage of the first part since an initial instant (Tq),said value (NPDFOQ(k) DAQ[kf being ^determined as a function of a value (NP Dq.( k) , DPQ^) of partial damage determined for portion k and as a function of a value Qq DAq (k - lp of damage determined for a portion k-1 of said data; and • an evaluation (S 140, S160), for portion k, of a residual life (PUL(k)) of the first part, as a function of the value (NpDFQq^ DAq^ of damage of the first part since the original instant (Tq).,

2. Evaluation method according to claim 1, wherein the ^NPDFOq value of damage of the first part since an origin time (Tq) corresponds to a normalized pseudo-damage determined since the origin time (Tq).

3. Evaluation method according to claim 1, wherein the value (DAq (ifp) of damage of the first part from an origin time (Tq) is a function of a sum of k -1 values ​​^DAç[k= k- 1 lp representing damage from an origin time (Tq) and determined for each of the k -1 portions treated prior to portion k.

4. Evaluation method according to any one of claims 1 to 3, further comprising: • a determination (S 100) of a number of operating quadrants to be considered, depending on whether the hydraulic system is supplied by a fluid having one or more pressure levels, and / or depending on whether the representative velocity data are signed or not, said value (NpDFQQ^ DAq. of damage to the part since an origin time (Tq) being determined for each of said quadrants, • the evaluation, for portion k, of a residual life (ULq ^j) of the first part comprises an evaluation (S 140) of a relative residual life associated with each of said quadrants (Qp ; and the evaluation of the residual life of the first part is further carried out as a function of the relative residual lives associated with said quadrants (Qp.

5. An evaluation method according to claim 4, wherein the hydraulic system comprises a multilobe cam comprising half-lobes, the system being alternately supplied with a fluid under high pressure and under low pressure, and the method further comprises: • a distribution of said data according to the half-lobes subjected to high pressure and the half-lobes subjected to low pressure; • and the determination of a residual life (R ULq (kp 'a first part is further implemented by distinguishing each of said half-lobes.

6. Evaluation method according to claim 4 or 5, wherein the remaining life of the first part corresponds to a value selected from the relative remaining lives and less than a predetermined threshold, or to the minimum relative remaining life.

7. Method for evaluating the remaining life of a part (^), called "second part", of a hydraulic system and subjected to a repeated or alternating load without relative movement with respect to said second part, the method being implemented iteratively on = XK portions of data representative of loads exerted on the second part: • a determination (S200), for a portion of data, of a number of damaging cycles by application of a cycle counting method; • a determination (S220), for the portion fa' of data, of a value (NDFO^k\ DA^kÿ of damage of the second part since an origin instant (Tq), said value (NDFO^k\ DA^k^ being determined as a function of the number of cycles determined, of a value (DP^k^ of partial damage determined for the portion k and of a value (NDFO^k-1)' DA^k -1)) of damage determined for a portion fa ' _ | of said data;and • an evaluation (S230), for the portion of a relative residual life (RUL^k'}^ as a function of the value (NDFOg[k)' DA^k} of damage of the second part since the original instant (Tq).;

8. Evaluation method according to claim 7, wherein the value (NDFO^k^) of damage of the second part since an origin time (Tq) corresponds to a normalized damage since the origin time (Tq) or to an average of values ​​(NDg(k)) representative of a determined partial normalized damage for each of the portions.

9. Evaluation method according to claim 7, wherein the value (DAç^k^ of damage of the second part since an origin time (Tq) is a function of a sum of | values ​​(DAg(k = k - Ll)) of damage since an origin time (Tq) and determined for each of the _ portions.

10. An overall method for evaluating the remaining life of a hydraulic system comprising at least one part, referred to as "first part", with a rotating relative load and at least one part, referred to as "second part", subjected to a repeated or alternating load without relative movement with respect to said second part, the overall method comprising: • an implementation, for at least one first part, of the method for evaluating a remaining life according to any one of claims 1 to 6; • an implementation, for at least one second part, of the method for evaluating a remaining life according to any one of claims 7 to 9; and • a determination (S800) of the remaining life of the hydraulic system as a function of the remaining lives associated with at least one first part and at least one second part.

11. A computer program comprising instructions for carrying out an evaluation method according to any one of claims 1 to 6, an evaluation method according to any one of claims 7 to 9 and / or an overall evaluation method according to claim 10, when said program is executed by a computer.

12. Computer-readable recording medium on which a computer program according to claim 11 is recorded.

13. Electronic device (10) configured to implement an evaluation method according to any one of claims 1 to 6, an evaluation method according to any one of claims 7 to 9 and / or an overall evaluation method according to claim

14. IV. System (1000) for evaluating a remaining life comprising the electronic device (10) according to claim 13, and further comprising a hydraulic machine configured to operate alternately as a pump and as a hydraulic motor.

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