A method for managing a vehicle's engine to prevent over-acceleration

Abstract

A motor vehicle management method comprising: - control means, - first electronic means determining a torque request to be supplied by the motor and delivering a corresponding output signal (TQ_spt), and - second electronic means to control the first electronic means - receiving data determined by the first electronic means, - calculating the torque to be supplied by the motor, and - transmitting instructions to the first electronic means, with the following steps: - derivation of the torque request (TQ_mod) determined by the first electronic means, - derivation of the torque (TQ_req) to be supplied by the motor calculated by the second electronic means, - determination of the difference between the two derivatives, - comparison with a predetermined limit value (JK_lim) and adaptation of the torque to be supplied (TQ_spt) so that the calculated difference becomes less than said limit value.Figure from the summary: Figure 3.

Description

Title of the invention: Method for managing a vehicle engine to prevent over-acceleration

[0001] This disclosure relates to a method for managing a vehicle engine to prevent over-acceleration, as well as to such a vehicle. It relates more particularly to electric motors, as well as vehicles powered by an electric motor (two-wheeled vehicles such as motorcycles, cars, four-wheeled all-terrain vehicles (also called "quads"), etc.). Technical field

[0002] The technical field of the present invention is thus the field of motor control, more particularly of electric motors but also of other motors such as internal combustion engines. To ensure proper motor operation and in particular to comply with safety standards, it is necessary to control various motor operating parameters, such as vehicle speed, motor torque, etc. Previous technique

[0003] An engine management system can activate or deactivate a limp-home mode if a fault appears or disappears, respectively. Most often, the limp-home mode involves limiting the vehicle's speed and / or limiting the torque delivered by the engine.

[0004] In an internal combustion engine, reaction times are relatively long, and a change in torque is therefore relatively slow to produce a risk of accident. In contrast, with an electric motor, variations in acceleration can generate jerking in the vehicle, both when the limp mode is activated and when it is deactivated. These jerks will be all the more noticeable to the driver of the vehicle when its mass is low, due to mechanical inertia. Therefore, the following disclosure is primarily, but by no means exclusively, addressed to light electric vehicles, such as electric motorcycles.

[0005] By way of purely illustrative and non-limiting example, during a cold start of a motorcycle, its battery may reach a low charge level corresponding to a failure limit. As a result, the engine management system will limit the motorcycle's maximum speed and / or limit the torque delivered by the engine. If the rider wishes to go faster than the imposed limit or accelerate harder than the torque limit allows, they will tend to operate the throttle beyond the limit(s) imposed by the engine management system. If at that moment, for example after a period of riding, the battery charge level If the engine temperature rises above the lower limit, the management system switches the engine from degraded operating mode to its normal operating mode. Due to the position of the throttle control, the motorcycle will therefore accelerate suddenly, which is not what the rider expected, causing them to be surprised.

[0006] This disclosure is based on the original finding that during a transition from normal operating mode to degraded operating mode, or vice versa, driving inconveniences may occur.

[0007] The purpose of this disclosure is to provide means to limit, and preferably eliminate, any risk of jerking for a vehicle when switching from operation from a degraded mode to a normal operating mode and / or vice versa. Summary

[0008] According to this disclosure, a method for managing a vehicle engine is proposed, said vehicle comprising: - means of controlling said engine by a driver, - of the first electronic means receiving as input a signal representing an action on said control means and / or signals received from sensors, determining from these signals a torque request to be supplied by the motor and delivering as output a torque control signal to the motor, and - second electronic means for controlling the first electronic means - receiving as input the aforementioned signals received as input by the first electronic means, as well as data determined by the first electronic means, - calculating the torque to be supplied by the motor, and - transmitting instructions to the first electronic means to possibly adapt the torque request determined by the first electronic means so that the torque control signal at the output of the first electronic means corresponds to the torque to be supplied by the motor, said process comprises the following steps: - calculation of an initial over-acceleration corresponding to a variation over time in the torque request determined by the initial electronic means, - calculation of a second over-acceleration corresponding to a variation over time of the torque to be supplied by the engine, calculated by the second electronic means, - determination of the difference between the value of the first over-acceleration and the value of the second over-acceleration, - comparison of said difference with a predetermined limit value and if this difference in absolute value is less than said limit value, the instructions of torque control of the second electronic means to the first electronic means are retained and, if not, they are modified in such a way that the calculated difference becomes less in absolute value than said limit value.

[0009] Such a method offers an original way of analyzing a curve derived from a torque curve, thereby limiting variations in torque and consequently in the acceleration of the corresponding vehicle. Jerking and other vehicle jerks can thus be avoided.

[0010] In a process such as that described above, the features set forth in the following paragraphs may optionally be implemented, independently of each other or in combination with each other:

[0011] - when the torque control instructions are modified, they are modified in such a way so that the torque control has a linear torque variation range less than a maximum value;

[0012] - said method is implemented during a transition from operation to mode normal operation towards degraded mode operation and / or vice versa.

[0013] According to another aspect, a computer program is proposed comprising instructions for the implementation of a process presented above when this program is executed by a processor, in particular an electronic control unit of an internal combustion engine.

[0014] According to another aspect, a non-transient, computer-readable recording medium is proposed on which such a program is recorded.

[0015] According to another aspect, an electronic system for managing a motor is proposed, configured to implement all the steps of a process described above, and comprising: - a position sensor for a vehicle control component; - a computer equipped with electronic memory, configured for: - to receive as input data provided by the position sensor and / or data provided by other sensors, - provide instructions for implementing the steps of a process described above, and - send instructions corresponding to a torque value to be supplied by a motor.

[0016] According to another aspect, a motor vehicle is proposed, characterized in that it comprises an electronic system as described in the preceding paragraph. Such a vehicle may include, for example, an electric motor, whether or not combined with another motor. Brief description of the drawing

[0017] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the attached drawing, on which: Fig. 1

[0018] [Fig.1] is a schematic representation of a prior art control unit architecture. Fig. 2

[0019] [Fig.2] is a schematic representation illustrating the action proposed by this disclosure on an architecture of the type illustrated in [Fig.1]. Fig. 3

[0020] [Fig.3] is a graphical representation explaining a method in accordance with this disclosure. Fig. 4

[0021] [Fig. 4] is a set of curves illustrating the variation of various parameters during an example of the implementation of a process according to this disclosure. Fig. 5

[0022] [Fig.5] is a schematic view of a vehicle for the implementation of this disclosure. Description of the implementation methods

[0023] This description relates to any vehicle powered by an engine. This could be, for example, a car, a motorcycle, or a four-wheeled recreational vehicle (also called a "quad"). The engine may be, for example, but not exclusively, an electric motor. The vehicle may have a hybrid architecture (with, for example, an internal combustion engine and at least one electric motor).

[0024] Typically, such a vehicle has at least one electronic control unit. This electronic unit is specifically designed to manage the engine(s). Figure 1 represents a known engine management system in a vehicle.

[0025] On this [Fig.1], the vertical mixed line symbolizes the limit of an electronic control and management unit (known by the English acronym "ECU") or computer, said unit being located to the left of this mixed line and comprising first electronic means forming a first module L1 corresponding to a first level of control and management and second electronic means forming a second module L2 corresponding to a second level of control and management.

[0026] The first level L1 module is a module intended for motor management, while the second level L2 module, for safety reasons, is intended for controlling the actions / instructions provided by the first L1 module. Thus, the first L1 module receives, for example, various SC information from several sensors (incoming arrows), one of which in particular This corresponds to instructions given by a driver to the engine regarding the torque to be delivered by said engine. Most often, the control means operated by the driver is an accelerator pedal, and the information provided to the first module L1 corresponds to the pedal position (PP) of this accelerator pedal, which is representative of the torque required by the driver. Other SC information from various sensors (pressure, temperature, etc.) constitutes additional input for the first module L1. Finally, after verification by the second module L2, it is the first module L1 that will provide an SM control signal to the engine as its output.

[0027] The second module L2 performs a check by receiving, on the one hand, information (not necessarily all of it) received by the first module L1, including in particular the PP position of the accelerator pedal (or equivalent: the "throttle" grip, for example, on a two-wheeler). It also receives data from the first module L1, more specifically the data to be checked. In return, the first module L1 receives confirmation from the second module L2 of the data provided by the first module L1 and / or instructions such as, for example, to switch to degraded operating mode, to return to normal operating mode, etc. Several degraded operating modes may exist: for example, a mode limiting the vehicle's speed or a mode limiting the torque supplied by the engine.

[0028] External control is also implemented, thus providing a third level of control and management. Third electronic means, forming a third electronic module L3 physically located outside the electronic control and management unit (ECU), control the operation of the first module L1 and the second module L2. For this control, the third-level module L3 exchanges data with the second module L2. The second module L2 can request the third module L3 to stop the engine or reset the electronic control and management unit. This engine stop (STOP) and / or reset of the electronic control and management unit (ECU) are commanded by the third module L3 if necessary.This third level L3 module thus controls the operations of the second level L2 module as well as the proper functioning (memory and computer) of the first level L1 module.

[0029] Such an overall architecture is known to those skilled in the art and may have variations depending on the manufacturers, but most often for safety reasons there are two levels of control with respect to a first module L1 which receives information and / or instructions and processes them to send instructions, for example a torque value to be supplied, to the motor associated with said module.

[0030] Figure 2 reproduces the elements of Figure 1, which retain the same function. Note here the addition of a module L1', which is schematically illustrated as a a separate module to better explain the interactions proposed by this description, but which physically can be integrated into the second module L2. We can consider here the module L1' as a software element placed between the first module L1 and the second module L2 and not a separate hardware element.

[0031] In a completely original way, the present disclosure proposes to control the variations in acceleration to prevent the vehicle, while driving, from having jerky handling or, in other words, from experiencing jolts and jolts.

[0032] As shown in the illustrative diagram in [Fig. 2], the second module L2 communicates to module Ll' the torque curve it provides for motor control. Module Ll' then determines, from this torque curve, a first over-acceleration curve (the "jerk" curve) corresponding to the derivative of the torque curve.

[0033] In parallel with this determination of an over-acceleration, the module Ll' will determine a second over-acceleration curve corresponding to the derivative of a torque curve defined by the first module Ll from the instructions (PP) provided by the driver.

[0034] The idea is then to compare the instructions received from the driver through their actions on the control means (accelerator pedal, twist grip, control lever, etc.) with the instructions that the second module L2 has validated or modified before sending them via the first module L1 to the engine, and to see if these instructions correspond or if they are "far removed" from each other. The comparison here is not performed on torque curves but on over-acceleration curves, that is, curves derived from the torque curves under consideration. If the variation is too significant, that is, if it exceeds predetermined values, then the torque curve provided by the second module L2 is adjusted by the module L1' so that the engine is controlled smoothly, without jerking or hesitation.

[0035] This process is shown in more detail in figures 3 and 4.

[0036] Figure 3 shows a "box" with input instructions (PP) given by a driver and output a torque (TQ_spt) to be supplied by a motor. Inside said box, a subset is identified: it corresponds to a proposed contribution of the present disclosure compared to a known prior art management system.

[0037] Based on instructions (PP) corresponding, for example, to the position of an accelerator pedal, a first-level (software) function FL1 will determine a required torque curve that corresponds, in terms of torque, to the driver's request when the driver presses the accelerator pedal (it is assumed hereafter that the control means available to the driver is an accelerator pedal, but any other means functions similarly). If, under various conditions, a degraded engine operating mode must be adopted, it will be necessary to modify the curve corresponding to the torque setpoint. We then obtain a modified torque curve TQ_mod which corresponds for example to the required torque curve but for which, during an operating period, the torque will be limited to a value TQ_lim.

[0038] A second-level (software) function FL2, using the same PP data, also calculates a corresponding torque curve.

[0039] This disclosure proposes to differentiate over time (d / dt operation) the modified torque curve TQ_mod and the required torque curve TQ_req (calculated by the FL2 function). The results obtained by these two differentiation operations are fed into a comparator (+ / -) which provides a difference whose absolute value abs is considered. This absolute value is compared to a predefined value JK_lim. These operations are schematically represented in [Fig. 3], in a region enclosed by a dashed line. If the said absolute value abs remains below JK_lim, then the modified torque curve TQ_mod, which may correspond to the required torque curve calculated by the FL2 function, is validated and becomes the torque curve TQ_spt, which then corresponds to the torque instructions supplied to the motor.However, if the absolute value abs exceeds the value JK_lim, then the instruction torque curve TQ_mod provided by the FL1 function is modified so that the torque variations of this curve are attenuated.

[0040] Figure 4 illustrates the process described above with illustrative curves.

[0041] The first curve, PP, shows the variations in the position of an accelerator pedal. By pressing the accelerator pedal, a driver provides instructions to the vehicle's engine to indicate whether they want the vehicle to travel faster or slower. They thus control the vehicle's acceleration. This acceleration is correlated with the torque transmitted to the vehicle's wheels. This torque corresponds approximately to the torque supplied by the engine(s), taking into account the transmission ratio (the transmission efficiency, which is always less than 1, can also be included here).It is thus noted that engine torque is linked to vehicle acceleration and this disclosure proposes to work from engine torque because it is the quantity usually used to manage an engine, but in theory another torque quantity, such as wheel torque or vehicle acceleration, could also be considered.

[0042] The TQ_req curve represents the translation of the driver's action on the accelerator pedal into torque. For the vehicle to accelerate as illustrated by the PP curve showing the position of the accelerator pedal, the engine used to move the vehicle must supply a torque according to the required torque curve TQ_req shown.

[0043] The modified torque curve TQ_mod assumes that during a period of time, the function FL1 determined that the motor should operate in degraded mode and that the torque supplied by the motor could not exceed a value TQ_lim (as shown in [Fig.3]).

[0044] The derivative curves of TQ_req and TQ_mod are calculated. The derivative curve of TQ_req is not shown, but it can be seen from the TQ_req curve that the torque variations are limited and very gradual. The overacceleration (i.e., the derivative of the acceleration, or here of the torque, which is considered an equivalent value) is practically zero.

[0045] Curve J1 illustrates the variation of the modified torque TQ_mod. It is noted here that the over-acceleration given by J1 has a significant negative value corresponding to the torque limitation to the torque TQ_lim, and then has a significant positive value because the torque demand abruptly changes from the value TQ_lim to a higher torque value.

[0046] The over-acceleration curve J1 is then modified into curve J2. Just as the curve TQ_mod corresponds to the curve TQ_req with locally a torque limited to TQ_lim, the curve J2 corresponds, for example, to the curve J1 in which the over-acceleration value is limited to a value JK_lim. The peaks of J1 are thus replaced by plateaus of absolute value JK_lim or, preferably, a value less than JK_lim, for example, JK_lim * 0.9 or JK_lim * 0.5.

[0047] By then integrating the curve J2, we obtain the torque curve to be supplied TQ_spt determined by the module L1', which is supplied to the first module L1, which consequently transmits torque instructions to the motor via the SM signal. It is noted that when the over-acceleration value is capped at a limit value (JK_lim or a proportion of this limit), the torque value increases linearly, and therefore the vehicle's acceleration is progressive, without jerks or stutters.

[0048] The method described above is preferably implemented by an electronic unit installed on board a vehicle, for example, a motor vehicle. This electronic unit corresponds to the electronic control unit (ECU), also known by its English acronym, the CPU. As schematically illustrated in [Fig. 5], there is a vehicle V powered by a motor M, said motor being electronically controlled by at least one electronic CPU. The motor M is, for example, an electric motor. Industrial application

[0049] The present technical solution can be applied in particular to motor control. It is more specifically intended for the control of one (or more) electric motor(s), whether or not associated with a thermal engine, but it can also be considered more generally for the control of any motor. Indeed, compared to In an electric motor, torque variations in an internal combustion engine are slower due to the inertia of an internal combustion engine in changing its torque.

[0050] In a completely original approach, it is proposed here to control over-acceleration. This improves the driving comfort of a vehicle. This improvement is all the more noticeable the lighter the vehicle. Indeed, the vehicle's mass increases its inertia, and variations in acceleration are partially "absorbed" by the vehicle's mass.

[0051] As explained in this disclosure, the additional control introduced here does not require the presence of a new sensor and can be achieved by software, without modification of the structure of the electronic control and management unit.

[0052] This disclosure is not limited to the proposed embodiment examples and variants described above, which are only examples, but encompasses all variants that a person skilled in the art may consider within the framework of the protection sought.

Claims

1. Demands A method for managing a vehicle engine, said vehicle comprising: - means of controlling said engine by a driver, - of the first electronic means (L1) receiving as input a signal (PP) representative of an action on said control means and / or signals (SC) received from sensors, determining from these signals a torque request (TQ_req) to be supplied by the motor, and delivering as output a torque control signal (TQ_spt) to the motor, and - second electronic means (L2) for controlling the first electronic means (L1) - - receiving as input the aforementioned signals (PP) received as input by the first electronic means (L1) as well as data determined by the first electronic means (L1), - - calculating the torque to be supplied by the motor (TQ_mod), with torque limited to a value TQ_lim during motor operation in degraded mode, and - transmitting instructions to the first electronic means (Ll) to possibly adapt the torque request determined by the first electronic means (Ll) so that the torque control signal (TQ_spt) at the output of the first electronic means (Ll) corresponds to the torque to be supplied by the motor (TQ_mod), said process comprises the following steps: - calculation of a first over-acceleration corresponding to a variation over time of the torque request (TQ_req) determined by the first electronic means (Ll), - calculation of a second over-acceleration corresponding to a variation over time of the torque to be supplied by the motor (TQ_mod) calculated by the second electronic means (L2), - determination of the difference between the value of the first over-acceleration and the value of the second over-acceleration, - comparison of said difference with a predetermined limit value (JK_lim) and if this difference in absolute value is less than said limit value, the torque control instructions from the second electronic means to the first electronic means are retained and otherwise they are modified in such a way that the calculated difference becomes less in absolute value than said limit value.

2. A method according to claim 1, characterized in that when the torque control instructions are modified, they are modified such that the torque control (TQ_spt) has a linear torque variation range less than a maximum variation. A method according to claim 1 or 2, characterized in that it is implemented during a transition from normal mode operation to degraded mode operation and / or vice versa.

3. An electronic engine management system configured to implement all the steps of a process according to any one of claims 1 to 3, and comprising: - a position sensor of a vehicle control element; - an electronic control unit (ECU) equipped with electronic memory, configured to: - receive input data (PP) provided by the position sensor and / or data provided by other sensors, - provide instructions to implement the steps of a process according to any one of claims 1 to 3, and - send instructions corresponding to a torque value (TQ_spt) to be provided by an engine.

4. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out all the steps of a process according to any one of the claims 1

5. a J. Non-transient, computer-readable recording medium, characterized in that a computer program according to claim 5 is recorded on said medium.

6. Vehicle, characterized in that it comprises an electronic system according to claim 5.

7. Vehicle according to claim 7, characterized in that it comprises at least one electric motor.

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