FR2958710A3 - Gear ratio determining method for transmission system i.e. gear box, of motor vehicle, involves utilizing kinetic information of motor vehicle and vehicle drive motor, where information includes longitudinal displacement speed information - Google Patents

Abstract

The method involves utilizing kinetic information of a motor vehicle (10) and a drive motor (13) of the motor vehicle, where the kinetic information includes information of longitudinal displacement speed of the motor vehicle and information about rotation speed of wheels (14, 15) of the motor vehicle. The ratio of the kinetic information of the motor vehicle and the drive motor is compared with values stored in a memory. The values stored in the memory characterize different gear ratios of a transmission system (18). Independent claims are also included for the following: (1) a data recording medium having a set of instructions for executing a gear ratio determining method (2) a transmission system for a motor vehicle (3) a computer program having a set of instructions for executing a gear ratio determining method.

Description

The present invention relates to a method for determining the transmission ratio engaged in a transmission system of a motor vehicle. The invention also relates to a determination system implementing such a method. It still relates to a vehicle comprising such a determination system. The invention finally relates to a computer program.

In a motor vehicle comprising a transmission system with several transmission ratios, it is important to know the current transmission ratio, that is to say the transmission ratio active at a given moment. This information can be used by other equipment of the motor vehicle to optimize the operation of the motor vehicle. This information can also be issued to the driver, especially when the vehicle does not have transmission ratio selection means that easily allows the driver to identify the transmission ratio actually engaged. In this document, the term "transmission ratio" is understood to mean the state of a system making it possible to vary the transmission ratio or the speed ratio between the output of the driving motor of the motor vehicle and the wheels of the vehicle. automobile. Such a system comprises for example a gearbox provided with several selectively activated gear pairs to vary the transmission ratio. In other words, the term "transmission ratio" corresponds, in current language, to the term "speed", a gearbox comprising for example a "first gear", a "second gear", a "third gear", a "fourth gear". "speed", "fifth gear" and "sixth gear" means a first gear ratio, a second gear ratio, a third gear ratio, a fourth gear ratio, a fifth gear ratio and a sixth gear ratio. . In this document, the terms "transmission ratio" and "gear ratio" or "gear ratio" are used as synonyms. MS \ REN252FR.dpt The determination method according to the invention can be applied to any type of vehicle with gearbox and in particular with a transmission system of the four-wheel drive type. Indeed, in such a transmission system, knowledge of the engaged transmission ratio can optimize its operation. In particular, in the case of a controlled actuator (semi-permanent torque transmission) it improves the thermal protection of the coupler for linking the two axles of the vehicle. In addition, it also improves the strategies of adaptation of the slip between these two axles in an automatic transmission type 4 * 4 mode where the torque transmitted from one axle to another is variable.

In particular, the determination method can be integrated in a global system whose hardware architecture comprises at least a 4x4 mode selection button, a measured or estimated temperature information of the 4x4 coupler, a longitudinal vehicle speed information and a means of sound or visual reproduction such as for example a light emitting diode display on a dashboard to indicate the gear ratio engaged.

It is known to use position sensors to determine the gear ratio actually engaged. However, such a solution is relatively complex and generates costs.

The object of the invention is to provide a method of determining a committed transmission ratio to overcome the problems mentioned above and improving the determination methods known from the prior art. In particular, the invention proposes a simple and economical method of determining that makes it possible to dispense with any position sensor in order to determine the transmission ratio actually engaged, regardless of the transmission technology (manual, automatic, robotic, etc.). ). MS \ REN252EN.dpt The method according to the invention makes it possible to determine the gear ratio engaged in a transmission system of a motor vehicle. It includes the use of kinetic information of the motor vehicle and kinetic information of the drive motor of the motor vehicle.

The kinetic information of the motor vehicle may include information on the longitudinal speed of movement of the motor vehicle. The kinetic information of the motor vehicle may comprise information on the speed of rotation of at least one wheel of the motor vehicle, preferably the average rotational speed of the two wheels of the same axle of the motor vehicle, more preferably the average rotation speed of the four wheels of the motor vehicle. The method may comprise a comparison of a ratio of the kinetic information of the motor vehicle and the drive motor to values contained in memory. The values contained in memory can characterize the different transmission ratios of the transmission system. The method may include a verification step that the transmission ratio is actually engaged.

The verification step may comprise calculating the absolute value of the difference between a kinetic information ratio of the motor vehicle and the driving motor, and the ideal transmission ratio of a transmission ratio, and the comparison of this absolute value with a threshold. The invention also relates to a data storage medium readable by a computer on which is recorded a computer program comprising computer program code means for implementing the steps of the previously defined method.

According to the invention, the transmission system of a motor vehicle comprises hardware and / or software means for implementing the determination method defined above. According to the invention, the motor vehicle comprises a transmission system defined above.

The invention also relates to a computer program comprising a computer program code means adapted to perform the steps of the method defined above, when the program runs on a computer.

The appended drawing shows, by way of example, an embodiment of a determination method according to the invention and an embodiment of a transmission system according to the invention.

Figure 1 is an embodiment of a motor vehicle comprising a transmission system according to the invention. FIG. 2 is a diagram of an electronic architecture governing the operation of a transmission system according to the invention and making it possible to implement the determination method according to the invention.

FIG. 3 is a diagram of an embodiment of a module of a computer implementing the determination method according to the invention. Figure 4 is a detailed diagram of an embodiment of a block of the previously mentioned module.

An embodiment of a motor vehicle 10 according to the invention shown in FIGS. 1 and 2 comprises an embodiment of a transmission system 18 of the four-wheel drive type 14, 15, and in particular of the driven four-wheel drive type. .

The transmission system 18 mainly comprises a first axle 17 of the motor vehicle wheels, for example a front axle, a second axle 19 of the motor vehicle wheels, for example a rear axle, a mechanical coupling means 11, for example a clutch controlled multi-disc with electromagnetic control, first and second axles (coupler) and a control system of the state of the mechanical coupling means. The control system comprises a means 21, in particular a button, for selecting the operating mode of the transmission system and a computer 20.

The transmission system is connected to a source 13 of driving torque of the motor vehicle (a vehicle drive motor).

Although not shown, the transmission system comprises means for determining vehicle state variables, such as, for example, means for obtaining the rotational speed of each wheel, means for obtaining the longitudinal speed of the vehicle, means for obtaining the rotational speed of the output shaft of the drive motor, means for obtaining the temperature of the coupler, means for obtaining status information of various vehicle equipment and electronic means or automatic calculation. The transmission system MS \ REN252FR.dpt comprises a user selection means (for example on the dashboard) of a system operating mode, in particular a first mode "4 * 4 Automatic", a second mode " 4 * 4 "All Terrain" or a third mode "4 * 2", a means of detection, from the variables of state of the vehicle and / or the system, the will of the driver and the driving conditions (acceleration, braking , slip ...) and a control means for switching the system in a mode determined according to the mode selected by the driver, the driver will and the driving conditions of the vehicle. The transmission system, in particular the control system of the mechanical coupling means also comprises a memory and all the hardware and / or software means for implementing the method that is the subject of the invention. In particular, the systems, in particular the computer, may comprise a computer program comprising computer program code means adapted to carrying out the steps of the method that is the subject of the invention.

In the transmission system, the first axle (for example the front axle or the rear axle) is driven by default by the torque source. On the other hand, the second axle (for example the rear axle or the front axle) is driven only optionnally according to the state of the coupler.

In this regard, depending on the state of the coupler, the transmission system has the following three modes of operation: a first transmission mode where only a part (variable) of the maximum torque capacity from the source of torque and intended the second axle is actually transmitted to the second axle; this first mode called mode "4 * 4 Automatic" corresponding to a coupler said "piloted", that is to say that the control system of the coupler automatically manages its operation, in particular the amount of torque transmitted or transmissible, MS \ REN252EN.dpt - a second transmission mode where the total maximum torque capacity from the torque source for the second axle is actually transmitted to the second axle; this second mode called mode "4 * 4 All Terrain" corresponding to a coupler said "closed", that is to say, it is locked in a state defining a fixed maximum torque value transmittable, - a third mode of transmission where no torque or negligible torque from the torque source is transmitted to the second axle; this third mode called mode "4 * 2" corresponding to a so-called coupler "open", that is to say that the coupler is disabled or transmits only a negligible amount of torque.

Technically, the coupler may be of the friction type, that is to say it has friction discs intended to come into contact with each other to transmit the torque and an actuator means to discard or bring these discs in contact with each other. The coupler may also be of the viscous fluid type (viscocoupler), that is to say that it comprises paddle wheels immersed in a fluid and an actuator means for spacing or bringing these wheels together. Whatever the technology of the coupler, the actuator means is controlled by the computer 20. The coupler may in particular be a multi-drive clutch driven current.

The transmission system may also comprise a computer 24 and means 22, 23 making it possible to transmit information to the driver, in particular a display 22 and / or a loudspeaker 23.

In one embodiment of the transmission system according to the invention, in the computer 20, a module 30 makes it possible to generate the following four output signals: MS \ REN252FR.dpt 1. The validity status of the gearbox ratio detected (V_Flag_1 bit_GearEngagedStatus); 2. The detected gear ratio (V_Flag_3bit_GearEngaged); 3. The ratio of the gearbox engaged detected (V_est_x_RatioEngaged); and 4. Confirmation of a gearbox gear engaged (V_FIag1 bit_GearEngagedConfirm).

As seen above, these four signals make it possible to dispense with an automatic or manual gearbox position sensor and to confirm that a gearbox ratio is actually engaged.

All of these signals can be measured from sensors (except a gear ratio position sensor) or estimated from estimated or measured intermediate measurements such as, for example, wheel speeds, gearbox ratios, speeds implemented in the vehicle equipped with this solution depending on the engine also implemented.

An exemplary embodiment of such a module 30 is shown diagrammatically in FIG. 3. Different signals attack the input module: 1. the average speed of rotation of the powered axle, (front axle for traction type vehicle, rear axle for propulsion type vehicle), in the example described here, the front axle (V_flt_rpm_AvgWheelSpeedFront) expressed in revolutions per minute, (the average speed of rotation of the wheels of the rear axle where the average speed of rotation of all the vehicle wheels could also have been chosen) 2. the engine speed (V_flt_rpm_EngineSpeed) expressed in revolutions per minute, MS \ REN252FR.dpt 3. the validity status each of the two previous signals can take the value of 0 or 1 respectively expressing 1 = valid signal and 0 = invalid signal. That is, respectively, the signals V flag_1 bit_AvgWheSpeedFrStatus and V flag_1 bit_EngineSpeedStatus.

The validity status of the output signals is therefore constituted by a logic AND of the set of validity signals previously mentioned, that is to say that the module output signals are only valid if the input signals of module are valid.

The module 30 thus makes it possible to generate the aforementioned output signals using the previously mentioned input signals.

To do this, the module 30 comprises a block 31 whose function is described below. This block 31 is shown in detail in FIG. 4. It is this block that carries out: the detection of the engaged transmission ratio, the calculation of the speed ratio associated with the transmission ratio engaged, and the confirmation of the commitment. the transmission report.

In this block, a sub-block "ratio-box recovery and range-ratio calculation" 32 recovers in memory the theoretical ratios of the speed ratios and calculates the ranges of gearbox reports. The ranges can be calculated or parameterized in order to adjust the thresholds of passage between two successive reports. These ranges are adapted for each model of gearbox and for each model of the engine integrated into the vehicle.

It is then possible to estimate and / or calculate a gear ratio from, among others, engine speed and vehicle wheel speeds. MS \ REN252FR.dpt An example of a method for determining the engaged gear ratio is given below.

As shown in FIG. 5, each gear ratio corresponds to an engine speed and an associated wheel speed range. This is the basic idea of determining the box ratio engaged from the data. Comparing, at a logic gate 36, for example the quotient between the engine speed (V_flt_rpm_EngineSpeed) and the average speed of rotation of the front wheels (V_flt_rpm_AvgWheelSpeedFront) (the quotient being made at a divider 35) and the pre-calculated optimal ratios in block 32. The signal of (V_flt_rpm_AvgWheelSpeedFront) is bounded by a minimum value strictly greater than zero and by a theoretical maximum value of the order of 200km / h. It is then determined at a gate 37 how many of these pre-calculated ratios are greater than this quotient. These pre-calculated ratios represent the possible minimum values of the quotient of engine speed and wheel speed. The result of this sum, performed at a summation operator 38, gives the detection of the gear engaged. In the example below, for a 6-speed gearbox, a table below shows the correspondence of the minimum threshold corresponding to the different gear ratios. Estimated gear ratio 1 2 3 4 5 6 Ratio 16.5 13.5 10.5 7.5 4.5 0 If the calculated quotient is 8, there are 2 pre-calculated ratios that are greater than the quotient, namely 16.5 and 13.5. 1 is added to this number because a box ratio of less than 1 is impossible. We then obtain 3 + 1 = 4 and we conclude that the engaged gear ratio is the fourth. MS \ REN252FR.dpt Any other processing of the speed information to determine the engaged gear ratio is of course possible.

Preferably, a test is performed to ensure that at all times, the operation of the transmission system is beyond the minimum conditions for estimating box ratios. Below this, it is assumed that the gear ratio engaged is the first gear, the gear ratio finally retained being outputted from the logic gate 39. In this test, at the logic gates 33 and 34, the speed is respectively tested. average wheel rotation is greater than a minimum speed and the engine speed is above a minimum speed.

For example, as the minimum engine speed P_fix_rpm_EngSpdGearDetectThrld, it can take 500 revolutions per minute and as the minimum front wheel rotation speed P_f ix_rpm_FASpdGearDetectThrld, it can take 50 revolutions per minute.

Subsequently, a sub-block determines whether the box report is actually engaged or not. That is to say that the case of an automatic or manual gearbox is determined if the clutch of the transmission is actually achieved. This sub-block makes it possible to construct the output signal "V_flag_1 bit_GearEngagedConfirm". To do this, we check whether the speed ratio or calculated quotient is in a certain tolerance around the speed ratio of the ideal box ratio (which can be contained in memory) with a parameter "P_fix_pct_GearDetectAccuracy". In addition, the block 31 outputs the ratio of the gear ratio associated with the speed engaged via the signal "V_est_x_RatioEngaged". For example, to consider that the gear ratio is well engaged it is necessary that the absolute value of the difference between quotient previously calculated and the ideal ratio of transmission of the report is less than a threshold defined by the parameter P_fix_pct_GearDetectAccuracy. MS \ REN252FR.dpt This information thus provided by block 31 makes it possible to improve the strategies of other functions. For example, for a 4x4 vehicle, it makes sure that the gear ratio is engaged.

The invention has been described above applied to a transmission system of the four-wheel drive type. Nevertheless, the invention can clearly be applied in the same way to a two-wheel drive transmission system, in particular a traction type transmission system or a propulsion type transmission system. Similarly, the invention can be applied both to a transmission system with automatic transmission or manually controlled gearbox, in particular manual gearbox with pulse selection. The gearbox can also be of the robotic type.

MS \ REN252FR.dpt

Claims (11)

1. A method for determining the transmission ratio engaged in a transmission system (18) of a motor vehicle (10), characterized in that it comprises the use of a kinetic information of the motor vehicle and of kinetic information of the drive motor (13) of the motor vehicle. 2. Determination method according to the preceding claim, characterized in that the kinetic information of the motor vehicle comprises a longitudinal speed information of the motor vehicle. 3. Determination method according to one of the preceding claims, characterized in that the kinetic information of the motor vehicle comprises a rotational speed information of at least one wheel (14, 15) of the motor vehicle, preferably the speed average rotation of the two wheels of the same axle (17, 19) of the motor vehicle, preferably still, the average speed of rotation of the four wheels of the motor vehicle. 4. Determination method according to one of the preceding claims, characterized in that it comprises comparing a ratio of the kinetic information of the motor vehicle and the drive motor to values contained in memory. 5. Determination method according to the preceding claim, characterized in that the values contained in memory characterize the different transmission ratios of the transmission system. MS \ REN252EN.dpt 1330 6. Determination method according to one of the preceding claims, characterized in that it comprises a verification step that the transmission ratio is actually engaged. 7. Determination method according to the preceding claim, characterized in that the verification step comprises calculating the absolute value of the difference between - a ratio of the kinetic information of the motor vehicle and the drive motor, and - the ratio ideal transmission of a transmission ratio, and the comparison of this absolute value to a threshold. 8. Data storage medium readable by a computer on which is recorded a computer program comprising computer program code means for implementing the steps of the method according to one of the preceding claims. 9. System (18) for transmitting a motor vehicle (10), characterized in that it comprises hardware and / or software for implementing the determination method according to one of claims 1 to 7. 10. Motor vehicle (10) comprising a transmission system (18) according to the preceding claim. 11. Computer program comprising computer program code means adapted to perform the steps of the method according to one of claims 1 to 7, when the program runs on a computer. MS \ REN252EN.dpt 30