FR2714506A1 - A method of managing the maintenance of a vehicle, on-board computer and associated diagnostic station implementing the method. - Google Patents

Abstract

The method of the invention makes it possible to carry out the monitoring of the wear of components whose state it is desired to constantly monitor, without requiring real-time storage of all the states. To achieve this goal, an accumulation of values representative of successive whispers is carried out on each journey, and the cumulative value stored in memory is compared with a threshold for triggering preventive maintenance.

Description

The present invention relates to a maintenance management method

  of a vehicle, as well as an associated on-board computer and diagnostic station

implementing the method.

  In the state of the art, the maintenance of a vehicle is carried out on the basis of a logbook of form most often handwritten, and periodic visits, or whose date is associated with a distance traveled, are necessary for good maintenance

vehicle.

  In particular, the manufacturer's warranty may

  only apply if these visits are made on time.

  However, the user may not follow these prescriptions for personal reasons, or because he can not materially. The vehicle does not receive its maintenance visit, which reduces its predictive reliability, and the vehicle owner may lose the benefit of

its guarantee.

  In the state of the art, we also know systems in which the logbook is made in computer form. In a known embodiment, the various maintenance phases are written on an electronic memory medium such as a memory card. The owner can then more easily manage the dates of maintenance visits, for example with a memory card reading station which signals

the next deadlines.

  But, so far, the dates are predetermined as in a contract and do not really take into account either the type of vehicle or the events that have happened to it and that actually modulate considerably the dates of visits necessary. In particular, a maintenance visit at fixed intervals does not take into account the wear of the vehicle in actual use. Such a visit can

  so intervene too early or too late.

  The present invention makes it possible in particular to take account of the history of the vehicle, when it is traveling or parked, so as to request the maintenance visit at times which correspond to probable failure states or significant probabilities. Indeed, the invention relates to a maintenance management method of a vehicle, wherein during an initial step: - wear parameters are determined which are then recorded; - wear functions are recorded; initial maintenance periodicity is defined for at least one unit to be monitored for maintenance; then, during an operating step: - the values of the various wear parameters are measured; the values of the various wear functions are calculated on the basis of the measurements of the values of the various wear parameters; the results of the calculations of the values of the wear functions are compared with predetermined thresholds, so as to deduce dates of advanced or delayed maintenance visits in relation to the periodicities

initials.

  In one embodiment, an alarm signal is generated from the comparison when the current date is close to a calculated maintenance visit date. The invention also relates to an on-board computer which comprises: an interface with sensors for measuring wear parameters; a memory in which the measurement values of said wear parameters are entered and updated; a memory in which are recorded dates of predetermined periods of maintenance visits; a central unit for calculating the value of at least one wear function on the basis of said values of the wear parameters; a circuit for comparing the value of said wear functions on the predetermined periodicity dates to produce a maintenance visit date for at least one given organ having an advance or a delay on said periodicity as a function of said values of the functions of 'wear; an output unit for producing an alarm signal if the current date is close to a date

maintenance visit.

  The invention also relates to a maintenance station which comprises at least one means of connection to the on-board computer. The maintenance station includes - means for associating parameter names and wear functions with each type of vehicle under maintenance; means for producing sets of parameters and wear functions and for recording them in at least one on-board computer of a vehicle of a given type; means for reading the memories of said computer and / or for receiving an alarm signal produced by said on-board computer when the current date is close to a maintenance visit date; means for producing a maintenance report. Other features and advantages of the present invention will be better understood using the

  description and drawings that are:

  - Figure 1: a flowchart of the initialization phase of the method of the invention; - Figure 2: a flowchart of the operating phase of the method of the invention; - Figure 3: a diagram of a device implementing the method of the invention mainly comprising: a vehicle with its organs under maintenance, wear parameter measurement sensors, a computer board, a maintenance station ; - Figure 4: a diagram of another mode of

  performing a part of the method of the invention.

  The method of the invention comprises two distinct phases: an initialization phase of the on-board computer 1 (see FIG. 1); - a maintenance operation phase

preventive measure (see Figure 2).

  In FIG. 1, an embodiment of the first initialization step of FIG.

method of the invention.

  In this step, the manufacturer determines the wear parameters of the vehicle components he intends to use.

  submit to preventive management.

  Then, depending on the characteristics of the vehicle, its customers, it determines wear functions associated with each organ, and possibly,

  for a specific vehicle, to a type of use.

  The initialization step is normally performed

  once when the vehicle is customized.

  But, as soon as important changes occur on the vehicle (mounting of options, modifications of a component, etc.), it must be executed again for

  update values and programs.

  When the initialization step of the process starts, an operator (man equipped with an input member on the on-board computer, or PLC connected to the on-board computer at the output of the assembly line, or still at the dealership before the sale of the vehicle), fixes the determination of the wear parameters. These parameters depend on: - wear sensors installed on the vehicle in question;

  - preventive maintenance plans retained.

  In one embodiment, all of the

  values is loaded into a protected memory of the vehicle.

  The operator has an access key, for example in the form of a procedure programmed in the software that implements the initialization step, which, at its execution, requires the entry of a password. , or using a means of authorization such as a smart card. This procedure allows you to access

  secure to sensitive data for the builder.

  Finally, the operator sets the initial periodicity of the visits for each type of vehicle, and for each

kind of use.

  As will be explained below, the wear parameters and functions, and the calculation modes of the periodicities are held by the manufacturer or dealer of the vehicle model, and this, vehicle by vehicle. The vehicle's onboard computer has a protected memory area to which only the manufacturer or its authorized agents may access so as not to compromise the confidentiality of such data. In this case, the necessary values are arranged in tables stored in memory addresses protected by a software access procedure and a fuse in the addressing areas prevent addressing from the outside. The means of protection of access are of the hardware or software type and within reach

of the skilled person.

So ends the first phase

  initialization of the process of the invention.

  In Figure 2, there is shown an embodiment of the step of operating the preventive maintenance management method of the invention. The vehicle comprises an on-board computer of which at least one section is reserved for carrying out the method of the invention. It also includes wear sensors associated with each wear parameter for each member of the vehicle under preventive maintenance. Each sensor is connected by a suitable connection (current loop, RS232, optical tree, ...) to the onboard computer by a circuit, said interface, as is well known in

sensor technology.

  At each start of the vehicle, or more generally, at each call of the operating step of the method of the invention on the preventive maintenance management computer, directly by the user on the call of the user. access (keyboard, touch screen, voice command, etc.), or indirectly by activation using the diagnostic station, the method consists in reading the current value of the wear parameters determined in particular according to the associated wear sensor , and transmits these values of the sensor interfaces to the mainframe operators to execute the computation of the significant current value of the functions

programmed wear.

  The current values of the wear functions are then passed to a comparison routine at wear thresholds that produce, if they are reached or exceeded,

predetermined alarms.

  Among these alarms, one can go from the alarm formed by a simple registration in an alarm memory, through an immediate alarm in the form including: - an audible message produced by a sounder or by the loudspeaker d a speech synthesis system; - a readable message produced by indicator lights or pictograms or by an alphanumeric message on a screen,

and perceptible by the user.

  In Figure 3, there is shown the block diagram of an assembly implementing the method of the invention. Such an assembly mainly comprises a vehicle computer 1 on board a vehicle and a preventive maintenance diagnostic station 2 installed at the dealer or repairer, who

perform the maintenance.

  The onboard computer 1 and the preventive maintenance station 2 are connected by a connector 3 at two different times in the life of the vehicle. Firstly in an initialization phase, the on-board computer 1 is loaded with predetermined values of constants of wear functions in the form of tables stored in permanent programmable memory and by wear functions in the form of a program. To do this, the on-board computer 1 comprises a programmable memory 4 for recording the constants of the wear functions, a program memory 5 and a central unit 6 which manages the data exchanges and the

  specific treatment of the invention.

  One solution to the problem of preventive maintenance could have been to keep a history of all the events occurring at the vehicle. But, such a history would occupy a place in memory and then require means of treatment that would make the system too complex, too expensive and too

  sensitive for the goals to be achieved.

  The solution of the invention consists in accumulating the events taken into account for the management of the preventive maintenance. According to a first embodiment of the invention, a wear function F of the form F (t) = F (t-1) + H (t) is defined for each member of the vehicle to which the preventive maintenance is applied. ) ... (1) where t is the current date, tl is the previous date, H is the change in wear function of

the organ in question.

  It is therefore conceivable that the function H and the value F (0) must be loaded into the on-board computer when

an initial phase.

  In one embodiment, the function H is of the additive type and comprises two parts: H (t) = HD + Hp ... (2) o HD indicates a function of the distance traveled by the vehicle between the dates t and tl ; Hp indicates a dependent function directly

  at least one wear parameter of the member under consideration.

  The function HD depending on the distance is, in a preferred embodiment, carried out by calculation: HD = a * D ... (3) where a coefficient depends on the organ in question and / or the vehicle in which it is embedded, and D is the distance According to the invention, the on-board computer has a connection interface to wear parameter sensors, which at each instant t, produce values

  pi, i = 1, 2, ..., wear of the organ considered.

  Or the case of a braking member. A first wear sensor consists of a thickness sensor of the brake lining. Let pl be the wear parameter associated with the thickness of the lining. We associate with the parameter p1 a threshold s1 such that if p1 becomes smaller than the threshold s1, we calculate from this moment the

  distance D (pl, sl) traveled between dates t-1 and t.

  The function Hp becomes: Hp = a * D (pl, sl) ... (3)

at the date t.

  If we add a wear state sensor of the drive system of the movable braking members by means of a pressure drop sensor constituted by a pressure sensor disposed in the braking circuit, we therefore associate a second wear parameter p2 and its threshold s2. We introduce an additional function of distance traveled, of the form D (p2, s2), analogous to D (pl, sl) and the function Hp becomes: Hp = a * D (pl, si) + b * D (p2, s2) ... (4)

at the date t.

  In general, if a member whose maintenance is monitored by the method of the invention comprises n wear sensors, the wear function is of the form: F (t) = F (tl) + a * D + Sum (ai * D (si, pi)) (5) o Sum indicates the summation operator of

all products ai * D (si, pi).

  To perform the calculation of the wear function associated with the member under consideration, the computer comprises an operator 6 to: read the previous value F (tl) of the wear function F: read the coefficient a in a memory of coefficients corresponding to the organ considered on the vehicle, the value of the distance traveled since the date tl, on a link interface to the traveled distance sensor which produces the value D; - calculate the term a * D; read the coefficients ai in a memory of coefficients corresponding to the organ considered on the vehicle, read the threshold values if in a memory of thresholds corresponding to the organ considered on the vehicle, read on the interface of the sensors of wear values, the current value of the wear parameters pi, - calculate each of the terms ai * D (pi, si), add it to the previous terms up to the last available term, and add the result of the summation operator

  and the term a * D at the value F (t-1).

  In one embodiment, the succession of operating instants of the method of the invention is determined according to a law recorded in the on-board computer. In a preferred embodiment, this law is cyclic constant of given period I. The successive instants of exploitation t and t-1 are therefore nI and (n-l) I. The step of calculating the wear function of the member in question is completed. This step may be repeated for each of the vehicle components that are under preventive maintenance of the invention. This repetition can take place: using the same operator 6, looping on the sequence described above successively for each of the organs under maintenance; with the aid of K similar operators working concurrently, at least one member under maintenance being

processed by one of the K operators.

  In one embodiment, the sequencing of the operating step is caused by an internal clock of the on-board computer. In this way, the time difference between t and t - 1 can be controlled according to

  the vehicle or any other parameter.

  As a variant, the calculation takes place as soon as

  the operator is freed by the previous calculation.

  Then, the on-board computer continues its task of managing preventive maintenance. It then includes a comparator of the present value of the

  wear function F (t) at a threshold value Fseuil.

  If the value of F (t) exceeds the value F threshold, then the on-board computer triggers an alarm of

Preventive maintenance.

  In fact, in the preferred embodiment, the comparison of the current value F (t) with the threshold value F threshold is an economical means in computing and memory means for comparing the wear of each member in

  preventive maintenance to reference wear.

  In another embodiment, the degree of wear of each member is associated with a pre-maintenance operating time that is compared to a preventive maintenance date. The wear function is then compared directly in terms of

Preventive maintenance.

  In the preferred embodiment, the invention consists in that, during the initialization phase, functions have been loaded to produce equivalent wear distances for each member. The possibly weighted accumulation of these equivalent distances makes it possible to compare an overall wear with a threshold wear for a preventive maintenance visit, thus making it possible to transform a control over the dates.

  in control over equivalent distances.

  In another embodiment, according to a less elaborate mode of the invention, the behavior of the vehicle for each organ is defined by at least one of the following parameters: - period T since the last maintenance intervention (in particular calculated in number of days), - a distance equivalent D traveled since the last maintenance intervention (in particular calculated in kilometers), - a predetermined number (8 in a preferred example) of distance equivalent meters corresponding to a type of use of the vehicle, - an IT intervention period (in days), - an anticipation threshold over this period allowing a maintenance alarm to be triggered before the maximum period is extinguished, - a distance between interventions (in kilometers traveled), - a threshold anticipating this distance to trigger a maintenance alarm before the distance between the intervention is traveled, - a predetermined number (8 in a preferred example) weighting coefficients, a coefficient being assigned to each type of use, - the characteristic parameters of wear for the organ considered in the form of distance thresholds or periods, such as the temperature operating pressure, operating pressure, engine speed, etc. For each organ, the degree of wear is then defined as the ratio: - either between the period elapsed since the last intervention on the predetermined period of intervention, - or between the distance equivalent traveled since the last intervention on the equivalent distance

predetermined number of interventions.

  The distance equivalent traveled since the last intervention is defined as the sum of the usage types of the products of the distance equivalent counters by their respective weighting coefficients. In order to take into account the global wear, this distance is added to the distance of the actual path OD effected by its

  own weighting coefficient KO.

  The updates of the counters are carried out during the stopping of the vehicle. To protect the vehicle from repetitive starts, a blocking of a predetermined duration, for example, greater than 1 minute is carried out before allowing the update processing of the counters. In addition, the update is carried out only if the information used by the model is tested.

as valid.

  At the start of the vehicle, the different thresholds are checked to the values of the aforementioned counters, to produce an alarm signaling all operations

necessary maintenance.

  Once the maintenance intervention has been performed, the maintenance computer asks the user, the manufacturer, or the maintenance mechanic to validate the operation of erasing the wear counters, and the preventive maintenance management. resumes

his courses.

  In order to allow the interfaces between the maintenance process and the person responsible for this maintenance, provision is made for: - a pull-down menu allowing the driver to perform the necessary operations without learning, - a diagnostic tool for the manufacturer

or the maintenance mechanic.

  In another embodiment, a user matrix was first developed for each member to deduce the maintenance conditions as a function of the environment on the one hand, and the style of use on the other hand . For example, the matrix consists of five lines describing the environment and four columns describing the style of use. For each couple style, environment is associated a distance counter, a duration counter, and

  a table of weighting coefficients.

  In Figure 4, there is shown such a matrix and its calls to counters that results and the execution of the accumulation operation. The matrix shown at the top of FIG. 4 is associated with the organ Oi under preventive maintenance. It is understood that there is a matrix associated with each

  organs Oi under preventive maintenance.

  The columns are respectively the definition of the following environments: - city V; - road R; - motorway A; - mountain M; - Deformed roadway C. The style of use of the vehicle is defined on four lines which are: - economic driving E; - normal driving N; - sports driving S; - Severe driving X. At the intersection of a row and a column of the matrix associated with the organ Oi are recorded the access pointers to different counters represented in the tables described below: the registered pointers in the matrix Oi are obtained from threshold values on the measurement values of the various parameters of speed, temperatures, flow rates (water, gasoline, oil, etc.) and reports of boxes etc. In a first embodiment, a distance counter D, a duration counter T, and a weighting counter K are used for each member Oi. The access pointers to these three counters are directly obtained by reading the matrix of the organ Oi. , thanks to a read-matrix circuit. This read-matrix circuit determines the style-environment pair according to the conditions of use of the vehicle at the instant when one

  performs the operation step of the method of the invention.

  The read-matrix circuit accesses the pointers i which allow access to the three counters mentioned above. As a result, an accumulation circuit receives the values Ai respectively from the distance counter D, bi coming from the timer T and Ki from the weighting counter. The accumulation circuit deduces the functions

  wear according to the above teachings.

  In another embodiment, the two distance meters D and duration T are replaced by a single counter equivalent distance D. In this case, the accumulation circuit receives only one parameter of distance equivalent di at the same time as the coefficient

  Ki weighting. Accumulation is performed as above

  above. It is clear that the accumulation circuit has as many inputs as just described.

  that there are organs under preventive maintenance.

  The duration counter serves as a pointer to address the weighting coefficient table at each change of state to allow updating

the distance counter.

  The wear function is then the sum of the different distance counters on all couples style, environment. Its instantaneous value is compared to a predetermined threshold to trigger the message

asking for the maintenance action.

Claims (27)

  1. A method of managing the maintenance of a vehicle, wherein during an initial step: - wear parameters are determined which are then recorded; - wear functions are recorded; - Periodicities are defined. initial maintenance visits for at least one maintenance monitor; then, during an operating step: - the values of the various wear parameters are measured; the values of the various wear functions are calculated on the basis of the measurements of the values of the various wear parameters; the results of the calculations of the values of the wear functions are compared with predetermined thresholds, so as to deduce dates of advanced or delayed maintenance visits with respect to the initial periodicities. 2. Method according to claim 1, characterized in that one further produces an alarm signal from the comparison when the current date is close to a   date of maintenance visit calculated.   3. Method according to claim 1, characterized in that the wear parameters and functions are accessed by a secure procedure comprising several levels reserved in particular: to the vehicle manufacturer: for the characteristic data of the vehicle; - the vehicle repairer: for maintenance and update data; - to the user of the vehicle: for the dates of maintenance visit.   4. Method according to claim 1, characterized in that the periodicity of the visits of   maintenance depending on the vehicle and the type of use.   5. Method according to claim 1, characterized in that the operating step is performed at each start of the vehicle, and / or at each call of the operating step via an on-board computer on board vehicle and / or through a diagnostic station.   6. Method according to claim 1, characterized in that at each instant (t) of execution of the operating step, the events taken into account are accumulated.   for the management of preventive maintenance.   7. Method according to claim 6, characterized in that the taking into account of events is performed cyclically. 8. Method according to claim 6, characterized in that for each member of the vehicle to which the preventive maintenance is applied, a step of calculating a wear function F of the form: F (t) = F (t -1) + H (t), in which H denotes the function of evolution of the wear of the member under consideration, the function H and the value F (0) being loaded into the computer of edge during an initial phase.   9. Method according to claim 8, characterized in that the function H is of the additive type and comprises two parts H (t) = HD + Hp, o HD indicates a function of the distance traveled by the vehicle between the dates t and t -1, and Hp indicates a function directly dependent on at least one wear parameter of the organ considered. 10. Method according to claim 9, characterized in that the function HD depends on the distance, and is in particular executed during a calculation step according to: HD = a * D, where a is a coefficient dependent on the organ considered and / or the vehicle on which it is embarked, and D is the distance   11. Method according to one of claims 6 to   10, characterized in that it is repeated for each organ in preventive maintenance, the partial results being   accumulated together between successive instants.   12. The method of claim 6, characterized in that to determine the behavior of the vehicle for each organ is calculated at least one of the following parameters: - T period elapsed since the last maintenance intervention (in particular calculated in number of days), - a distance equivalent D traveled since the last maintenance intervention (in particular calculated in kilometers), - a predetermined number (8 in a preferred example) $ of distance equivalent meters corresponding to a type of use of the vehicle, - a period of TI intervention (in days), - a threshold of anticipation over this period to trigger a maintenance alarm before the extinction of this maximum period, - a distance between interventions (in kilometers traveled), - a threshold of anticipation on this distance allowing a maintenance alarm to be triggered before this distance between intervention is traversed, - a predetermined number (8 d in a preferred example) weighting coefficients, a coefficient being assigned to each type of use, - the characteristic parameters of the wear for the organ considered in the form of distance or period thresholds, such as the operating temperature , operating pressure, engine speed etc. 13. The method of claim 12, characterized in that for each member, the degree of wear is calculated as the ratio: - or between the period elapsed since the last intervention on the predetermined period of intervention, - or between the equivalent distance traveled since the last intervention on the equivalent distance predetermined number of interventions.   14. Method according to claim 13, characterized in that the distance equivalent since the last intervention is calculated as the sum of the types of use of the products of the distance equivalent counters by their weighting coefficient. respective.   15. The method of claim 14, characterized in that to take into account the global wear, the distance of the distance actually traveled DO, with its own coefficient, is added to the value of the distance equivalent traveled since the last intervention. weighting K0, and   update treatments of the meters.   16. The method according to claim 15, characterized in that the updating treatments of the   counters are performed when stopping the vehicle.   17. The method as claimed in claim 16, characterized in that, to protect the vehicle from repetitive starts, a blocking of a predetermined duration, for example greater than 1 second before   to allow the update process of the meters.   18. A method according to claim 15, characterized in that a validity check of the preventive maintenance model is performed so as to execute the updating process only if the information used by the model is valid.   19. The method of claim 1 or claim 18, characterized in that, at the start of the vehicle, a comparison test is performed of the different thresholds with respect to the values of the aforementioned counters, to produce an alarm signaling all the   necessary maintenance operations.   20. The method as claimed in claim 19, characterized in that, once the maintenance intervention has been carried out, a validation step is carried out by the user, the constructor, or the maintenance mechanic, of the erasing operation of the wear counters, and resumes the preventive maintenance management. 21. The method of claim 1 or 6, characterized in that it consists: - to develop for each member a use matrix to deduce the maintenance conditions according to the environment on the one hand, and style of use on the other hand;   - to measure in execution the couple style-   environment adopted by the vehicle; - to associate with each couple styleenvironment a distance counter, a duration counter, and a table of weighting coefficients; using the duration counter as a pointer for addressing the weighting coefficient table during each state change to make it possible to update the distance counter; - to calculate the wear function as the sum of the different distance counters on all couples style, environment; comparing its instantaneous value with a predetermined threshold to trigger the message requesting the maintenance action.   22. On-board computer implementing the preventive maintenance management method according to one of   any of claims 1 to 21, characterized in that   it comprises: an interface with sensors for measuring wear parameters; a memory in which the measurement values of said wear parameters are entered and updated; a memory in which are recorded dates of predetermined periods of maintenance visits; a central unit for calculating the value of at least one wear function on the basis of said values of the wear parameters; a circuit for comparing the value of said wear functions on the predetermined periodicity dates to produce a maintenance visit date for at least one given organ having an advance or a delay on said periodicity as a function of said values of the functions of 'wear; an output unit for producing an alarm signal if the current date is close to a date maintenance visit.   23. Computer according to claim 22, characterized in that it comprises communication interfaces with wear sensors that transmit values of wear parameters to the operating process. 24. Computer according to claim 22, characterized in that it also comprises a secure access unit adapted to several security levels and using an input means of an authentication key. like a smart card.   25. Maintenance station for implementing the preventive maintenance management method on an on-board computer according to any one of   claims 22 to 24, characterized in that   comprises at least one means of connection to the on-board computer, and in that it also comprises: means for associating parameter names and wear functions with each type of vehicle under maintenance; means for producing sets of parameters and wear functions and for recording them in at least one on-board computer of a vehicle of a given type; o - a means for reading the memories of said computer and / or for receiving an alarm signal produced by said on-board computer when the current date is close to a maintenance visit date; means to produce a balance sheet of maintenance.   26. Preventive maintenance station according to claim 25 and / or computer according to claim 22, characterized in that, to allow the interfaces between the maintenance process and the person responsible for this maintenance, they comprise: - menu software dropouts enabling the driver to perform the necessary operations without learning, - a diagnostic tool for the manufacturer or the maintenance mechanic.   27. Preventive maintenance station according to claim 25, characterized in that it also comprises a secure access unit adapted to several security levels and using an input means of a   authentication key as a smart card.