Method for evaluating a residual service life of a part of a hydraulic system, and associated electronic device

Abstract

The invention relates to a method for evaluating a residual service life of a part of a hydraulic system, the method being implemented iteratively on k=1...K data portions and comprising: - determining, for a data portion k, a damage value for the part from an initial moment in time, the value being determined on the basis of a partial damage value determined for the data portion k and on the basis of a damage value determined for a data portion k-1; and - evaluating, for the portion k, a relative residual service life of the part on the basis of the damage value for the first part from an initial moment in time.

Description

METHOD FOR EVALUATING THE RESIDUAL LIFE OF A PART OF A HYDRAULIC SYSTEM, AND ASSOCIATED ELECTRONIC DEVICE Description Technical Field

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

[0002] A hydraulic system is made up of components that pose a risk to operators, particularly when supplied with high-pressure fluid.

[0003] The main causes of accidents caused by pressurized hydraulic fluids are typically linked to a lack of maintenance which then risks causing leaks of pressurized fluid following a leak in the seal, but also a rupture of a component or part of the system.

[0004] Also, such a system requires specific maintenance methods which aim to keep 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 predict the occurrence of a failure and to be able to anticipate a maintenance schedule. To do this, the state of health and the level of operation of the system parts are assessed, and a residual service life (or "Remaining Useful Life", RUL, according to Anglo-Saxon terminology) before the occurrence of a breakdown is determined. In this way, it is possible to plan the appropriate maintenance operations at the most opportune time, and in particular before the breakdown occurs.

[0006] However, the methods for assessing a residual life implemented to date require acquiring and storing a significant amount of raw data before being analyzed, and are therefore not suitable for being implemented "on the fly". Disclosure of the invention

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

[0008] To this end, and according to a first aspect, the invention relates to a method for evaluating a residual service life of a part, called "first part", of a hydraulic system, the first part being at relative rotating load, the method being implemented iteratively on ^ = 1.. ^ portions of data representative of pressure of a fluid within the hydraulic system and data representative of rotation speeds of said hydraulic system, by an electronic device and comprising:

[0009] – a determination, for a portion ^ of data, of a value representative of damage to the first part since an original instant, said value being determined as a function of a value representative of partial damage determined for the portion ^ and as a function of a value representative of damage determined for a portion ^ − 1 of said data; and,

[0010] – an assessment, for portion ^, of a residual life of the first part, based on the representative value of damage to the first part since the original time.

[0011] Thus, advantageously, to determine the residual life of the first part at the iteration of index ^ , only the representative value of partial damage determined during this iteration ^ (for the portion ^) and the representative value of damage determined for the portion ^ − 1 of said data must be able to be accessed. This portion ^ − 1 immediately precedes (in time) the portion k which corresponds, for its part, to the current portion considered for evaluating a residual life.

[0012] Tel qu'évoqué plus en détail ci-après, la valeur déterminée "pour la portion ^ − 1" covers the case of a value determined at iteration ^ − 1 for this portion of index ^ − 1, but also that of a value determined at iteration ^ − 1 for and / or as a function of each of the portions of index 1.. ^ − 1 considered from an original instant.

[0013] Each data portion ^ corresponds to a set of data captured during a predetermined and constant period, and these data portions define a certain frequency of evaluation of a residual life of a part of the system. In other words, the evaluation method 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 "relative rotating load" corresponds, for example, to the radial load on a rotating shaft in rotary bending, to the equivalent radial load on the cage or balls of a bearing, or to the cam reaction forces on the rollers of a hydraulic motor using radial technology.

[0016] The initial time mentioned above corresponds, for example, to the first use of the part whose residual lifespan is being assessed, or to the first commissioning of the hydraulic system.

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

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

[0019] This feature is advantageous in that these models allow for an equivalent number of cycles to be associated with an equivalent stress. By "cycle" is meant a load or stress cycle that causes or contributes to the progressive damage of a mechanical part over time. Indeed, as these cycles are repeated, the structure of the part is altered, which therefore reduces its strength.

[0020] Generally speaking, 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 method may further comprise one or more of the following characteristics, taken individually or in all technically possible combinations.

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

[0023] As is well known, the parts of a hydraulic system can be subject to several "damage modes". For example, it is common to have degradation of these parts by fatigue resulting from the application of forces on this part, by contact fatigue with a viscous body such as oil, or by a combination of these different fatigues. Damage modes by adhesive or abrasive wear can also be considered, provided that the wear or friction coefficients are known.

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

[0025] In particular embodiments, the method further comprises determining the value representative of partial damage for the portion ^.

[0026] In particular modes of implementation, the representative value of damage to the first part since an initial instant corresponds to a normalized pseudo-damage determined since the initial instant.

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

[0028] In particular modes of implementation, the representative value of damage to the first part since an original instant is a function of a sum of ^ − 1 values ​​representative of damage since an original instant and determined for each of the ^ − 1 portions treated prior to portion ^.

[0029] In particular modes of implementation, the evaluation method further comprises:

[0030] – a determination 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 data representing the speeds are signed or not,

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

[0032] the evaluation, for the portion ^, of a residual life of the first part comprises 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 according to the relative residual lives associated with said quadrants.

[0033] In particular embodiments, the hydraulic system comprises a multi-lobe 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 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 residual life of the first part corresponds to a value selected from the relative residual lives and less than a predetermined threshold, or to the minimum relative residual life.

[0036] According to a second aspect, the invention relates to a method for evaluating a residual service life of a part, called "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 ^^ = 1.. ^^ portions of data representative of loads exerted on the second part:

[0037] – a determination, for a portion ^ ^ of data, damaging cycles by applying a cycle counting method;

[0038] – a determination, for the portion ^ ^of data, of a value representative of damage to the second part since an original instant, said value being determined as a function of a result of the application of the cycle counting method, of a value representative of partial damage determined for the portion ^ ^ ^ and a representative value of damage determined for a portion ^^ ^− 1 of said data; and,

[0039] – an assessment, for the portion ^ ^ , of a relative residual life depending on the representative value of damage to the second part since an original instant.

[0040] Ainsi, de manière avantageuse, à l'itération d'indice ^^^ , seules la valeurrepresentative of a partial damage determined during this iteration^^^ (for the portion ^^^) and the representative value of a damage determined for the portion ^^ ^− 1 of said data must be able to be accessed. This portion ^^ ^− 1 immediately precedes (in time) the portion ^^^ which corresponds, for its part, to the current portion considered to evaluate a residual life.

[0041] Tel qu'évoqué plus en détail ci-après, la valeur déterminée "pour la portion ^^ − 1" covers the case of a value determined at iteration ^^ ^− 1 for this portion of index ^^ − 1, but also that of a value determined at iteration ^^ − 1 for and / or as a function of each of the portions of index 1.. ^^ − 1 considered from an original instant.

[0042] Each portion ^ ^^data corresponds to a set of data captured during a predetermined period, and these portions of data define a certain frequency of evaluation of a residual life of a part of the system. Thus, the evaluation method is applied on packets of records of finite and constant length.

[0043] Generally speaking, a part subjected to a load "without relative movement" refers to a mechanical part that supports a force or stress, but without there being any relative movement between its different parts or with its environment. Such a part is, for example, subjected to pressure pulsations or a series of alternating or repeated twists, without the rotation of a shaft being necessary, for example.

[0044] This second part can be, for example, a shaft, a shaft spline, a housing, an O-ring or a seal of any other profile, or a casing subject to pressure.

[0045] The initial time mentioned above corresponds, for example, to the first use of the part whose residual lifespan is being assessed, or to the first commissioning of the hydraulic system.

[0046] The method mentioned above is, for example, implemented until a stopping condition is reached. This stopping condition corresponds, for example, to a residual service life below a predetermined threshold, or to the detection of cracks or a break in said part.

[0047] In particular implementation modes, the parts for which a residual life is evaluated respond to an Inverse Power life model, for example the Basquin model.

[0048] This feature is advantageous in that these models allow an equivalent number of cycles to be associated with an equivalent constraint.

[0049] In particular modes of implementation, the cycle counting method applied corresponds to the cascade 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.

[0050] This cascaded extent counting method decomposes a complex load signal (e.g., a stress-time curve) into a series of representative load cycles. It is based on the fact that cycles are larger when the load varies significantly over time, rather than when it remains stable. To achieve this, the method focuses on identifying points where the load changes significantly and then grouping these variations to determine complete cycles.

[0051] In particular implementation modes, the cascade extent counting method applied complies with AFNOR standard A03-406, "Metallic products - Fatigue under variable amplitude stresses - Rainflow cycle counting method", published in November 1993.

[0052] In particular implementations, the representative value of a partial damage determined for the portion ^ is determined by applying the Palmgren-Miner method or the Manson Halford correction accumulation method. The Manson Halford correction accumulation method is 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.

[0053] In particular modes of implementation, the representative value of damage to the second part since an original instant corresponds to a normalized damage since the original instant or to an average of values ​​representative of a partial normalized damage determined for each of the ^ ^ portions.

[0054] In particular modes of implementation, the representative value of damage to the second part since an original instant is a function of a sum of ^^ − 1 values ​​representative of damage since an original instant and determined for each of the ^^ − 1 portions.

[0055] In particular modes of implementation, 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 residual life is considered.

[0056] In particular modes of implementation, the steps of this method are iterated for each of the damage modes of a second part of the hydraulic system, and the most unfavorable residual life is considered.

[0057] According to a third aspect, the invention relates to a global method for evaluating a residual service life of a hydraulic system comprising at least one part, called "first part", with rotating relative load, and at least one part, called "second part", subjected to a repeated or alternating load without relative movement with respect to said second part, the global method comprising:

[0058] – an implementation, for the at least one first part, of the method for evaluating a residual lifespan according to the first aspect;

[0059] – an implementation, for the at least one second part, of the method for evaluating a residual lifespan according to the second aspect; and,

[0060] – a determination of the residual service life of the hydraulic system based on the residual service lives associated with at least one first part and at least one second part.

[0061] 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.

[0062] This program may use any programming language, and may 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.

[0063] 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.

[0064] The information or recording medium may be any entity or device capable of storing the program. For example, the medium may include a storage medium, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a hard disk.

[0065] On the other hand, the information or recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention may in particular be downloaded from a network such as the Internet.

[0066] Alternatively, the information or recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to carry out or to be used in carrying out the method in question.

[0067] 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.

[0068] According to a seventh aspect, the invention relates to a system for evaluating a residual life 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

[0069] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures:

[0070] [Fig. 1] Figure 1 schematically represents an example of a system for evaluating a residual lifespan according to an example of implementation of the invention;

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

[0072] [Fig. 2B] Figure 2B represents modules embedded in an evaluation device, such as the evaluation device belonging to the system of Figure 1, according to a second example of implementation of the invention;

[0073] [Fig. 2C] Figure 2C represents modules embedded in an evaluation device, such as the evaluation device belonging to the system of Figure 1, according to a third example of implementation of the invention;

[0074] [Fig. 3A] [Fig. 3B] [Fig. 3C] Figures 3A, 3B and 3C schematically represent examples of hardware architecture of an evaluation device belonging to the evaluation system of Figure 1;

[0075] [Fig. 4] Figure 4 represents, in the form of a flowchart, a particular mode of implementation of a method for evaluating a residual service life of a rotating relative load part of a hydraulic system, for example executed by the evaluation device of Figure 2A;

[0076] [Fig. 5] Figure 5 represents, in the form of a flowchart, a first example of implementation of the method for evaluating the residual service life of a rotating relative load part of a hydraulic system;

[0077] [Fig. 6] Figure 6 represents, in the form of a flowchart, a second example of implementation of the method for evaluating the residual service life of a rotating relative load part of a hydraulic system;

[0078] [Fig. 7] Figure 7 represents, in the form of a flowchart, a particular mode of implementation of a method for evaluating a residual 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 executed by the evaluation device of Figure 2B; and

[0079] [Fig. 8] Figure 8 represents, in schematic form, an example of implementation of a global method for evaluating a residual service life of a hydraulic system, for example executed by the evaluation device of Figure 2C. Description of the embodiments

[0080] The terms "first(s)", "second(s)", etc. are used in this document by arbitrary convention to identify and distinguish different elements (such as components, mechanical parts, etc.) considered in the implementation methods described below. Thus, and unless otherwise stated, no notion of order should be associated with these terms.

[0081] Figure 1 schematically represents an example of a system for evaluating a residual lifespan, according to an example of implementation of the invention.

[0082] As illustrated in Figure 1, the system 1000 comprises a hydraulic machine 100 with radial pistons and multi-lobe cam. This hydraulic machine 100 is for example in accordance with that described in the patent document FR2846381B1 published on January 28, 2005. Alternatively, this hydraulic machine corresponds to the hydraulic motor with radial pistons described in the patent document FR2892775B1 published on November 5, 2010.

[0083] The hydraulic machine 100 comprises a casing defining an internal volume in which a shaft extending in 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 relative to the axial direction ZZ.

[0084] The hydraulic machine 100 also includes a multi-lobe cam positioned around the cylinder block. The cam defines a plurality of lobes adapted to cooperate with the pistons during operation of the hydraulic machine 100. The cylinder block is coupled to a distributor defining fluid supply and discharge conduits linked to the various housings in which the pistons slide. These conduits are also called "supply ports" in the remainder of the description.

[0085] For the hydraulic machine 100, a first assembly comprising the cylinder block and a second assembly comprising the casing and the cam are defined. The first assembly and the second assembly are movable relative to each other in rotation in the axial direction ZZ, one of these assemblies being fixed and the other movable depending on the application considered.

[0086] The hydraulic machine 100 is typically reversible. It may operate as a hydraulic pump (the system converts mechanical energy into hydraulic energy) or alternatively as a hydraulic motor (the system converts hydraulic energy into mechanical energy) depending on its use, the operation of such a hydraulic machine 100 being otherwise well known.

[0087] It should be noted, however, that considering a hydraulic machine constitutes only an alternative implementation of the invention. Generally speaking, no limitation is attached to the hydraulic system considered, which may correspond to a hydraulic pump, a hydraulic motor or a hydraulic machine which, as mentioned above, may have the operation of a hydraulic pump or a hydraulic motor.

[0088] The evaluation system 1000 further comprises an electronic device 10-1, 10-2, 10-3 for evaluating a residual service life of at least one part of the hydraulic machine 100.

[0089] As illustrated in Figure 1, the evaluation device 10-1, 10-2, 10-3 is connected to a rotation 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, to the evaluation device 10-1, 10-2, 10-3, data representative of the pressure of a fluid circulating within the hydraulic machine 100. These sensors 20-1, 20-2 make it possible, for example, to record the pressures of the fluid at the level of the fluid supply and discharge conduits. 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).

[0090] Figure 2A represents modules embedded in an evaluation device 10-1, such as the evaluation device belonging to the system 1000 of Figure 1, according to a first example of implementation of the invention.

[0091] As illustrated in Figure 2A, the evaluation device 10-1 includes in particular:

[0092] – a module MOD_DET_P1 for determining, for a portion ^ of data, a value ^^^^^^^(^), ^^^^(^) representative of damage to a part of the hydraulic machine 100 called "first part" since an original instant ^^, this first part being at relative rotating load, said value ^^^^^^^(^), ^^^^(^) being determined as a function of a value ^^^^^(^), ^^^^(^) representative of partial damage determined for the portion ^ and as a function of a value ^^^^^^^(^ − 1), ^^^^(^ − 1) representative of damage determined for a portion ^ − 1 of the data; and

[0093] – a MOD_EVAL_P1 module for evaluating, for this portion ^, a residual life (^^^^^(^)) of the first part, as a function of the value ^^^^^^^(^),^^^^(^) representative of damage to the first part since the original instant ^ ^ .

[0094] This first part can be, for example, a cam, a roller, or a bearing.

[0095] The relative rotating load corresponds, for example, to the radial load on a rotating shaft in rotary bending, to the equivalent radial load on the cage or balls of a bearing, or to the cam reaction forces on the rollers of a hydraulic motor with radial technology.

[0096] Figure 2B represents modules embedded in an evaluation device 10-2, such as the evaluation device belonging to the system 1000 of Figure 1, according to a second example of implementation of the invention.

[0097] As illustrated in Figure 2B, the evaluation device 10-2 includes in particular:

[0098] – a MOD_DET_CL determination module, for a portion ^ ^ of data, damaging cycles by applying a cycle counting method;

[0099] – a MOD_DET_P2 determination module, for this portion ^ ^ of data, of a value ^^^^ ^ (^ ^ ), ^^ ^ (^ ^ ) representative of damage to a part of the hydraulic machine 100 called "second part" since an original instant ^ ^ , this second part being subjected to a repeated or alternating load without relative movement with respect to said second part, said value ^^^^ ^ ^(^ ),^^^(^^) being determined as a function of a value ^^^(^^) representative of a partial damage determined for the portion ^^ and as a function of a value ^^^^^(^ − 1), ^^^(^ − 1) representative of a damage determined for a portion ^^ ^− 1 of said data; and

[0100] – an evaluation module MOD_EVAL_P2, for this portion ^ ^ , of a relative residual life (^^^ ^ (^ ^ )) of the second piece, depending on the value (^^^^ ^ (^ ^ ), ^^ ^ (^ ^ )) representative of damage to the second part since the original time ^ ^ .

[0101] This second part can be, for example, a shaft, a shaft spline, an enclosure or a casing subjected to pressure.

[0102] Figure 2C represents modules embedded in an evaluation device 10-3, such as the evaluation device belonging to the system 1000 of Figure 1, according to a third example of implementation of the invention.

[0103] As illustrated in Figure 2C, the evaluation device 10-3 includes the modules described with reference to Figures 2A and 2B.

[0104] Figure 3A schematically represents an exemplary hardware architecture of an evaluation device, such as the evaluation device 10-1 of Figure 2A.

[0105] As illustrated in Figure 3A, the evaluation device 10-1 has the hardware architecture of a computer. Thus, the evaluation device 10-1 comprises, in particular, a processor 1, a random access memory 2, a read-only memory 3 and a non-volatile memory 4. It also has communication means 5.

[0106] The read-only memory 3 of the evaluation device 10-1 constitutes a recording medium in accordance with the invention, readable by the processor 1 and on which is recorded a computer program PROG_P1 in accordance with one aspect of the invention, comprising instructions for executing steps of the method for evaluating a rotating relative load part. The program PROG_P1 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 cited above. These functional modules are illustrated in Figure 2A in a non-limiting manner, and are described in more detail below with reference to different modes of implementation.

[0107] The communication means 5 allow in particular 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 comprise a communication interface, wired or wireless, capable of implementing any suitable protocol known to those skilled in the art.

[0108] Figure 3B schematically represents an exemplary hardware architecture of an evaluation device, such as the evaluation device 10-2 of Figure 2B.

[0109] As illustrated in Figure 3B, the evaluation device 10-2 also has the hardware architecture of a computer, and differs from the evaluation device 10-1 in that the read-only memory 3 of the evaluation device 10-2 constitutes a recording medium on which is recorded a computer program PROG_P2 according to one aspect of the invention, comprising instructions for executing steps of the method for evaluating a part subjected to a repeated or alternating load without relative movement with respect to this part.

[0110] Figure 3C schematically represents an exemplary hardware architecture of an evaluation device, such as the evaluation device 10-3 of Figure 2C.

[0111] As illustrated in Figure 3C, the evaluation device 10-3 also has the hardware architecture of a computer, and differs from the evaluation devices 10-1 and 10-2 in that the read-only memory 3 of the evaluation device 10-3 constitutes a recording medium on which is recorded a computer program PROG_SYS according to one aspect of the invention, comprising instructions for performing steps of the overall method for evaluating a residual service life of a hydraulic system comprising at least a first part with rotating relative load and at least a second part subjected to a repeated or alternating load without relative movement with respect to said second part.

[0112] Figure 4 represents, in the form of a flowchart, a particular mode of implementation of a method for evaluating a residual service life of a rotating relative load part of a hydraulic system – called the first part –, for example executed by the evaluation device 10-1 of Figures 2A and 3A.

[0113] As mentioned above, parts for which a residual life is evaluated respond 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 constraint.

[0114] More formally, a Basquin model is expressed as follows:

[0115] with A and B two points respectively defined by the coordinates (^ ^ ;^^ ^ ^ ) and (^ ^ ;^^ ^ ^ ), ^ ^ ^ and ^ ^^ values ​​of the magnitude of an applied stress, and ^ ^ and ^ ^ values ​​of a number of cycles.

[0116] However, analyses carried out on the one hand between the stress versus the number of cycles, and on the other hand between the loading and the number of cycles, can give different Basquin slopes (i.e., slopes of the line (AB)).

[0117] Therefore, prior knowledge of the Basquin slope for a given part is necessary to implement this evaluation procedure.

[0118] As illustrated in Figure 4, the method for evaluating a residual service life of a rotating relative load part comprises a first step S0 during which a portion ^ of data representative of pressure of a fluid within the hydraulic system and data representative of rotation speeds of said hydraulic system is obtained.

[0119] The hydraulic system considered corresponds for example to the hydraulic machine 100, and the pressure data of a fluid are for example received from the sensors 20-1, 20-2 recording the fluid pressures at the fluid supply and discharge conduits. Furthermore, the data representative of rotation speeds correspond for example to rotation speeds of the first set or of the second set in the axial direction ZZ captured by the rotation speed sensor 30 of the hydraulic machine 100.

[0120] The method further comprises a step S100 during which a number of operating quadrants to be considered is determined.

[0121] The four operating quadrants of a hydraulic machine are classically 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 negative, and the machine then operates as a hydraulic pump; quadrant Q3 corresponds to the case where the torque and speed are negative, and the machine then operates as a hydraulic motor; and quadrant Q4 corresponds to the case where the torque is negative and the speed 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 supports on the cam, shafts, splines, keys, change locally.For example, depending on the direction of application of the torques, the splines of the splined shafts or cylinder blocks will be stressed on one side or the other. Depending on the direction of rotation and the direction of the torque applied, the cams will be stressed under high pressure, on a rising or falling lobe.

[0122] When the hydraulic machine is powered by a fluid that can have several pressure levels – typically high and low pressure of an open or closed loop circuit – at least two quadrants must be considered, for example the quadrants pair (Q1, Q4) or the pair (Q2, Q3).

[0123] Furthermore, 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 therefore to refine the areas of damage and wear of the rollers, pistons and supports.

[0124] Thus, when the data obtained are representative of high and low fluid pressures and the data representative of rotation speeds are signed, the evaluation of a lifetime can be implemented by distinguishing each of the four quadrants.

[0125] By distinguishing each of the quadrants, the evaluation process makes it possible to "redistribute" the damage more equitably, according to each of the operating quadrants.

[0126] The method for evaluating a residual life further comprises a step S110 during which the data obtained in step S0 are segmented according to the operating quadrants determined in step S100.

[0127] The method further comprises steps S120, S130 and S140 which are implemented for each of the quadrants determined in step S100. Step S120 corresponds to a determination of a value ^^^ ^^ ( ^ ) , ^^ ^^ (^) representative of partial damage for portion ^.

[0128] During a step S130, a value ^^^^^ ^^ (^), ^^ ^^ (^) representative of damage to the first part from an original instant ^ ^, is determined for the portion ^ of the data obtained. This step S130 is for example implemented by the module MOD_DET_P1 of the evaluation device 10-1. This value ^^^^^^^(^), ^^^^(^) is determined as a function of the value ^^^^^(^), ^^^^(^) determined in step S120, and as a function of the value ^^^^^^^(^ − 1), ^^^^(^ − 1) representative of damage determined for a portion ^ − 1. As mentioned above, this portion ^ − 1 immediately precedes (in time) the portion ^ which corresponds, for its part, to the current portion considered for evaluating a residual service life.

[0129] In step S140, a relative residual lifetime (^^^ ^^ (^)) of the first part, is evaluated according to the value ^^^^^^^(^) , ^^^^(^) representative of damage determined in step S130. This step S140 is for example implemented by the module MOD_EVAL_P1 of the evaluation device 10-1.

[0130] The evaluation method further comprises a step S150 in which it is determined whether the data associated with each of the %& = 1.. % quadrants determined in step S100 have been processed. If this is not the case (choice "N"), steps S120 to S140 are repeated. If, on the other hand, the data associated with each of the quadrants have been processed (choice "Y"), a step S160 is implemented during which a residual life ^^^(^) of the first part is evaluated based on the relative residual lives ^^^ ^^ (^) associated with each of the quadrants.

[0131] According to a particular mode of implementation, the residual life ^^^(^) of the part corresponds to a value selected from the relative residual lives ^^^ ^^(^) which is less than a predetermined threshold. Alternatively, the residual life of the part corresponds to the worst case, i.e., to the minimum relative residual life.

[0132] As mentioned above, a first dichotomy is implemented during step S110 based on operating quadrants. According to other implementation modes, this first dichotomy is further refined, based on particular elements of the part or component, such as lobes, bearings, etc.

[0133] In a particular case, the part is a radial piston driven into motion 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 administered to the main supply port of the radial piston hydraulic receiver, some cam lobes experience high-pressure forces, while others only experience low-pressure (LP) forces. In this particular case, the evaluation method includes an additional dichotomy according to the half-lobes undergoing high pressure and the half-lobes undergoing low pressure. In addition, the value ^^^^^ ^^ (^), ^^ ^^ (^) representative of damage to the first part from an original instant ^ ^ determined in step S130 is^determined for each of the half-lobes; the evaluation, for the portion ^, of a residual lifetime (^^^^^ (^)) of the first part comprises an evaluation of a relative residual life associated with each of said half-lobes; and the evaluation of the residual life of the first part is further implemented based on the relative residual lives associated with said half-lobes.

[0134] Alternatively, the first part is an axial piston or axial piston component, and a similar method is implemented.

[0135] Selon un mode particulier de mise en œuvre, seule la durée de vie résiduelle ^^^(^) of the first part is saved, for example in the nonvolatile memory 4 of the device-1, 10-2, 10-3. Alternatively, some or all of the relative residual lifetimes of the first part are saved (eg, the lifetimes associated with each quadrant, the lifetimes associated with each half-lobe, etc.).

[0136] The invention has so far been described in the particular case where the part is subjected to a single mode of damage. The invention nevertheless remains applicable in the case where the part is subjected to several (( ) modes of damage, for example by the application of forces on this part and by contact with a viscous body.

[0137] This aspect of the invention has also been described so far in the particular case where a single first part is considered. The invention nevertheless remains applicable in the case where several first parts are considered.

[0138] Figure 5 represents, in the form of a flowchart, a first example of implementation of the method for evaluating the residual service life of a rotating relative load part of a hydraulic system.

[0139] Prior knowledge of the transfer function between pressure and stress is required. Furthermore, it is subsequently assumed that the relationship between load and stress is linear, or log-linear. Otherwise, the Basquin model is applied directly to the stress.

[0140] As illustrated in Figure 5, the evaluation process includes a first step * +,-. during which an instant of origin ^ ^ , a SEQL duration of a portion, a reference pressure ^ / 0. , a reference rotation speed * / 0. , a reference lifetime ^ / 0. , and a reference normalized pseudo-damage^^^ / 0. = ^ ^ / 0. × * / 0. are defined, with b a slope of the Basquin model, for example equal to 3 or 1^ 2 in the bearing frame.

[0141] The method further comprises steps S100 and S110 previously described with reference to FIG. 4. The method also comprises a step S520 which corresponds to an example of implementation of step S120 mentioned with reference to FIG. 4. In this example, the value representative of partial damage for the portion ^ then corresponds to a normalized pseudo-damage ^^^ ^^ ( ^ ) This normalized pseudo-damage is expressed for example as follows:

[0142] ^^^ ^^ " = 1.. ^5

[0143] with ^ ( " ) a pressure value at a time ", * ( " ) a rotation speed value at this time", % & (") being equal to "0" if the quadrant % & does not match the one currently running", and % & (") being equal to "1" if the quadrant % &corresponds to the one in operation at time ", and ^5 the last time " of the data portion ^.

[0144] The method also comprises a step S530 which corresponds to an example of implementation of step S130 mentioned with reference to FIG. 4. In this example, the value ^^^^^ ^^ (^) representative of damage to the part since the original time ^ ^ is expressed as (^34^^4^(^^ ( )

[0146] En variante, ^^^^^^^(^) = ^^^ ^ ) " = 1.. ^ ^ ^

[0147] The method also comprises a step S540 which corresponds to an example of implementation of step S140 mentioned with reference to FIG. 4. In this example, the relative residual lifetime (^^^ ^^ (^)) of the first part is evaluated as follows:

[0149] with SEQL the duration of a portion.

[0150] Thus, during an iteration ^, this method only requires access to the following values: the partial damage for the portion ^ obtained at iteration ^, the normalized pseudo-damage from the origin ^^^^^^^(^ − 1) obtained at iteration^ − 1 , the iteration value k, and the reference values ​​^ / 0. , > / 0. , ^ / 0. previously mentioned.

[0151] Furthermore, it is important to note that using an iterative approach is advantageous in that it avoids storing large signals.

[0152] Figure 6 represents, in the form of a flowchart, a second example of implementation of the method for evaluating the residual service life of a rotating relative load part of a hydraulic system.

[0153] As before, prior knowledge of the transfer function between load and stress or damage variable is required. Furthermore, it is subsequently assumed that the relationship between load and stress is linear, or log-linear. Otherwise, the Basquin model is applied directly to the stress.

[0154] As illustrated in Figure 6, the evaluation process includes a first step * +,-. during which an instant of origin ^ ^ , a SEQL duration of a portion, a reference pressure ^ / 0. , a reference rotation speed > / 0. , a reference lifespan ^ / 0. , and ^4> / 0. a number of reference revolutions or cycles before break such that ^4> / 0. = * / 0. × ^ / 0. are defined.

[0155] The method further comprises steps S100 and S110 previously described with reference to FIG. 4. The method also comprises a step S610 of calculating the following quantities, for each quadrant %&, @ ∈ {1,2,3,4}

[0156] – an effective average pressure

[0157] – a weighted average speed

[0158] – a proportion ^^^^ ^^ (^)time spent in quadrant % & such as

[0159] The method also comprises a step S620 which corresponds to an example of implementation of step S120 mentioned with reference to FIG. 4. In this example, the value representative of partial damage for the portion ^ is expressed for example as follows:

[0161] Then a step S630 is implemented which corresponds to an example of implementation of step S130 mentioned with reference to figure 4. In this example, the value^^^^(^) representative of cumulative damage to the first part since an original instant ^ ^ is expressed as follows: ^^^^(^) = ^^^^^(^ − 1) + ^^^^(^)^

[0162] The method further comprises a step S640 which corresponds to an example of implementation of step S140 mentioned with reference to FIG. 4.

[0163] When the Palmgren-Miner damage accumulation method is applied (summing the results obtained in previous iterations), the relative residual life (^^^ ^^ (^)) of the first part is then expressed for example as follows:

[0164] ^^^^^(^) = ([^[(^((1 − ^^^^(^)) × 100

[0165] In this particular case, the result provided is expressed as a percentage, but a duration (e.g. in hours, minutes, seconds) could alternatively be considered.

[0166] As is well known, for parts subject to inverse power laws, the Palmgren-Miner damage accumulation law accounts for the total damage suffered by these parts. The potential life for a fixed load / stress is given by the Basquin model. According to the Palmgren Miner method, the Damage DA is:

[0167] avec abbcdefbeg : le nombre de cycles réalisés pour une amplitude de contrainte ^abbcdefbeg constant, and ^abbcdefbeg: the number of cycles that can be performed under a constant stress amplitude ^abbcdefbeg, for a predetermined admissible failure rate (for example 10%). The value of the cumulative damage of Palmgren-Miner is then between 0 and 1, "0" corresponding to a new part and "1" in the case where the predetermined admissible failure rate is reached.

[0168] Figure 7 represents, in the form of a flowchart, a particular mode of implementation of a method for evaluating a residual service life of a part – called the second part – of a hydraulic system subjected to a repeated or alternating load without relative movement with respect to the stressed / loaded part. This method is for example carried out by the evaluation device of Figure 2B.

[0169] 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.

[0170] This means that this second part does not, for example, suffer damage or wear caused by rotation relative to a fixed reference point.

[0171] As illustrated in Figure 7, the method for evaluating a residual life of a second part comprises a first step S0 during which a portion ^ ^ representative data of repeated or alternating loads is obtained.

[0172] 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.

[0173] The method further comprises a step S200 during which damaging cycles are determined by applying a counting method of cycles. This step S200 is for example implemented by the MOD_DET_CL module of the evaluation device 10-2.

[0174] The applied cycle counting method corresponds to the cascade 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, 1968.

[0175] This cascaded extent counting method decomposes a complex load signal (e.g., a stress-time curve) into a series of representative load cycles. It is based on the fact that cycles are larger when the load varies significantly over time, rather than when it remains stable. To achieve this, the method focuses on identifying points where the load changes significantly and then grouping these variations to determine complete cycles.

[0176] In particular modes of implementation, the cascade extent counting method is for example in accordance with the AFNOR A03-406 standard, "Metallic products - Fatigue under variable amplitude stresses - Rainflow cycle counting method", published in November 1993.

[0177] More precisely, to implement the cascade extent counting method, an analysis periodicity is predetermined and linked to the duration of the data portions ^ ^ considered during each iteration ^ ^ . In addition, a condition also determines whether cascade range counting should be implemented with or without residual closure.

[0178] This condition relates to a periodicity of closure of the residues. As long as the condition is not met, we iterate by extracting the residues from the current count, to then concatenate them before the next portion ^ ^. Then when the condition is reached, we close the residues during counting.

[0179] Le procédé comprend en outre une étape S210 au cours de laquelle une valeur ^^^(^^) representative of a partial cumulative damage is determined for the portion ^ ^ , based on a result from the implementation of the cycle counting method

[0180] In other words, for each count, the damage is accumulated, whether the residues are closed or not. If the residues are not closed, then the damage accumulated over the duration of the portion ^ ^ is locally lower, but the overall result is corrected when closing the residuals, since the residual is saved and then concatenated before the next data portion ^^ + 1 (of the ^^ + 1 iteration), and this, iteratively. Thus, the Rainflow count of the k+1-th portion is obtained by concatenating the residual of the k-th count.

[0181] Applying the Palmgren-Miner damage accumulation method over the duration of the portion ^^ , the value ^^ ^ (^ ^ ) is then expressed in the form:

[0183] with i a two-dimensional variable defining a position in a Rainflow results matrix – such as a position [amplitude, mean] in a 3D Rainflow matrix [amplitude, mean, number of cycles] –, & a number of damaging cycles performed and ^ & a number of achievable damaging cycles.

[0184] The use of the Palmgren-Miner damage accumulation method is only a 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.

[0185] Then, during a step S220, a value ^^^^ ^ (^ ^ ), ^^ ^ (^ ^ ) representative of damage to the second part from an original instant ^ ^ is determined. This step S220 is for example implemented by the MOD_DET_P2 module of the evaluation device 10-2. This value ^^^^ ^ (^ ^ ), ^^ ^ (^ ^) is determined based on the value ^^ ^ ( ^ ^) representative of partial damage determined for the portion ^ ^ (determined in step S210) and as a function of a value ^^^^^(^^ − 1), ^^^(^^ − 1) representative of a cumulative damage determined for a portion ^^ ^− 1 of said data.

[0186] The method further comprises a step S230 in which a relative residual lifetime ^^^(^^) is determined based on the value ^^^^ ^ ^(^ ), ^^^(^^) representative of damage determined in step S220. This step S230 is for example implemented by the MOD_EVAL_P3 module of the evaluation device 10-2.

[0187] According to a first example of implementation, the residual life of the second part is calculated in hours, minutes, seconds. In this case, the method comprises, following step S210, a step (not referenced) during which a normalized damage ^^ ^ (^ ^ ) is determined for the portion ^ ^ , and this for each part p. This normalized damage ^^ ^ ( ^ ^) is expressed for example in the form

[0188] with SEQL a duration of the portion ^ ^ .

[0189] According to this first implementation example, the value ^^^^ ^ (^ ^ ) representative of damage to the second part from an original instant ^ ^ determined in step S220 is then expressed in the form:

[0191] Alternatively, this value is calculated as an average of normalized damage and is then expressed as follows: ^

[0193] Finally, still according to this first example of implementation, the relative residual life ^^^(^ ^ ) of the part p determined in step S230 is then expressed for example as:

[0195] According to a second implementation example, the residual life of the second part is calculated as a percentage of residual life.

[0196] In this particular case, when the Palmgren-Miner damage accumulation method is applied to each of the second pieces p , the value ^^ ^ ^(^ ) representative of cumulative damage to the second part since an original instant ^ ^ (determined in step S220) is expressed as follows:

[0197] ^^ (^^) = ^^^ ( ^ ) ^ ^ ^ ^ − 1 +^^^^(^ ).

[0198] Finally, still according to this second example of implementation, the relative residual life ^^^(^ ^) of the part p determined in step S230 is then expressed for example as:

[0199] ^^^^(^^)=(1 − ^^^(^^)) × 100.

[0200] This aspect of the invention has so far been described in the particular case where a single second part p is considered. The invention nevertheless remains applicable in the case where several second parts are considered.

[0201] As mentioned above, the invention also relates to a global method for evaluating a residual service life of a hydraulic system comprising a first part with rotating relative load, and a second part subjected to a repeated or alternating load without relative movement with respect to said second part. This method is for example executed by the evaluation device of FIG. 2C and comprises:

[0202] – an implementation, for the first part, of the method for evaluating a residual service life as illustrated by one of figures 4, 5 or 6;

[0203] – an implementation, for the second part, of the method for evaluating a residual life as illustrated in Figure 7; and,

[0204] – a determination of the residual life of the hydraulic system based on the residual lives associated with the first and second parts.

[0205] This aspect of the invention has so far been described in the particular 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.

[0206] Figure 8 represents, in schematic form, an example of the implementation of a global process for evaluating the residual life of a hydraulic system.

[0207] This figure illustrates more specifically the case of a hydraulic system comprising two parts )1 and )] with a rotating relative load, and three parts p1,^p] and p2 subjected to a repeated or alternating fixed relative load. Part )1 is subjected to two modes And ' ] , and the part p ] is also subject to two damage modes '2and ' y .

[0208] As illustrated in Figure 8, the overall process is implemented iteratively for this hydraulic system and therefore includes:

[0209] – an implementation, for the part )1 subjected to damage mode '1, of the method for evaluating a residual life as illustrated by one of figures 4, 5 or 6 so as to obtain a first residual life, this method being referenced "PROC1" in figure 8;

[0210] – an implementation, for the part )1subject to the damage mode ' ], of the “PROC1” evaluation process so as to obtain a second residual life;

[0211] – an implementation, for the part) ] , of the “PROC1” evaluation process so as to obtain a third residual life;

[0212] – an implementation, for part p1, of the method for evaluating a residual life as illustrated in figure 7 so as to obtain a fourth residual life, this method being referenced "PROC2" in figure 8;

[0213] – an implementation, for the part p ] subjected to damage mode '2, of the method for evaluating a residual life as illustrated in figure 7 so as to obtain a fifth residual life, this method being referenced "PROC2" in figure 8;

[0214] – an implementation, for the part p ] subject to the damage mode ' y, of the "PROC2" evaluation process so as to obtain a sixth residual life; and

[0215] – an implementation, for part p2 of the evaluation process "PROC2" so as to obtain a seventh residual life.

[0216] The method further comprises a step S800 of determining a residual service life of the hydraulic system, as a function of the first, second, …, seventh residual service lives. According to a particular embodiment, the residual service life of the hydraulic system corresponds to a value selected from among the first, second, …, seventh residual service lives which is less than a predetermined threshold. Alternatively, the residual service life of the hydraulic system corresponds to the most unfavorable case, i.e., to the minimum residual service life of the first, second, …, seventh residual service lives.

Claims

Claims

1. Method for evaluating a residual service life of a part, called "first part", of a hydraulic system, the first part being at relative rotating load, the method being implemented iteratively on ^ = 1.. ^ portions of data representative of pressure of a fluid within the hydraulic system and data representative of rotation speeds of said hydraulic system, the data representative of pressure corresponding to measurements captured by a pressure sensor of the hydraulic system, the data representative of rotation speeds corresponding to measurements captured by a rotation speed sensor of the hydraulic system, the method being implemented by an electronic device (10) and comprising: - a determination (S130), for a portion ^ of data, of a value (^^^^^ ^^ (^), ^^ ^^ (^)) of damage to the first part since an original time (^ ^), said value (^^^^^ ^^ (^), ^^ ^^ (^)) being determined as a function of a value ( ^^^^^(^) , ^^^^(^) ) of partial damage determined for the portion ^ and as a function of a value ( ^^^^^^^(^ − 1) , ^^^^(^ − 1) ) of damage determined for a portion ^ − 1 of said data; and− an evaluation (S140, S160), for the portion ^, of a residual life (^^^(^)) of the first part, as a function of the value (^^^^^ ^^ (^), ^^ ^^ (^)) of damage to the first part since the original time (^ ^ ).

2. The evaluation method of claim 1, wherein the value (^^^^^ ^^ (^)) of damage to the first part since an original time (^ ^ ) corresponds to a normalized pseudo-damage determined from the original instant (^ ^ ).

3. An evaluation method according to claim 1, wherein the value of the first piece from an original time (^^) is a function of a sum of ^ − 1 values ​​(^^^^(^ = ^ − 1..1)) damage since an original instant (^ ^ ) and determined for each of the ^ − 1 portions processed prior to portion ^.

4. Evaluation method according to any one of claims 1 to 3, further comprising: − a determination (S100) 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 data representative of the speeds are signed or not, − said value (^^^^^ ^^ (^),^^^ ^^ ^(^)) of damage to the part since an original instant (^ ^ ) being determined for each of said quadrants, − the evaluation, for the portion ^, of a residual life (^^^ ^^(^)) of the first part comprises an evaluation (S140) of a relative residual life associated with each of said quadrants (% & ); and the assessment of the residual life of the first part is further implemented based on the relative residual lives associated with said quadrants (% & ).

5. An evaluation method according to claim 4, wherein the hydraulic system comprises a multi-lobe 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 undergoing high pressure and the half-lobes undergoing low pressure; − and the determination of a residual service life (^^^ ^^(^)) of the first part is further implemented by distinguishing each of said half-lobes.

6. An evaluation method according to claim 4 or 5, wherein the residual life of the first part corresponds to a value selected from the relative residual lifetimes and less than a predetermined threshold, or the minimum relative residual lifetime.

7. Method for evaluating a residual lifetime of a part (p), 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 ^^ = 1.. ^^ 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 applying a cycle counting method; − a determination (S220), for the portion ^^ of data, of a value (^^^^ ^ (^ ^ ), ^^ ^ (^ ^ )) of damage to the second part since an original instant ( ^ ), said value ^ ^^ r ( ^^^^^(^ ) , ^^^(^ ) ) being determined as a function of the number of cycles determined, of a value (^^ ^ (^ ^ )) of partial damage determined for the portion ^ ^ and a value ( ^^^^ ^ ^^(^ − 1) , ^^^(^ − 1) ) of damage determined for a portion ^^ ^− 1 of said data; and− an evaluation (S230), for the portion ^ ^ , of a relative residual life (^^^ ^ (^ ^ )), depending on the value (^^^^ ^ (^ ^ ), ^^ ^ (^ ^ )) damage to the second part since the original time (^ ^ ).

8. An evaluation method according to claim 7, wherein the value (^^^^ ^ (^ ^)) damage to the second part from an original time (^ ^ ) corresponds to a normalized damage since the original instant (^ ^ ) or to an average of values ​​(^^ ^ ( ^ ^) ) representative of a partial standardized damage determined for each of the ^ ^ portions.

9. The evaluation method of claim 7, wherein the value (^^ ^ (^ ^ )) of damage to the second part from an original time (^ ^ ^ ^^) is a function of a sum of ^ − 1 values ​​(^^^(^ = ^ − 1..1)) damage since an original instant (^ ^) and determined for each of the ^^ − 1 portions.

10. Overall method for evaluating a residual life of a hydraulic system comprising at least one part, called "first part", with rotating relative load and at least one part, called "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 the at least one first part, of the method for evaluating a residual life according to one of claims 1 to 6; − an implementation, for the at least one second part, of the method for evaluating a residual life according to one of claims 7 to 9; and − a determination (S800) of the residual life of the hydraulic system as a function of the residual lives associated with the at least one first part and the at least one second part.

11. A computer program comprising instructions for implementing 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. A computer-readable recording medium on which a computer program according to claim 11 is recorded.

13. An 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 10.

14. A system (1000) for evaluating a residual 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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