EP2855191A2

EP2855191A2 - System and method for monitoring the torque of a motor vehicle engine

Info

Publication number: EP2855191A2
Application number: EP13728451.9A
Authority: EP
Inventors: Marco Marsilia; Islam AIT-HAMMOUDA
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2012-05-30
Filing date: 2013-05-16
Publication date: 2015-04-08
Also published as: US9199552B2; US20150120116A1; WO2013178907A2; FR2991526B1; WO2013178907A3; BR112014029818A2; JP2015536122A; RU2014153516A; FR2991526A1; CN104349927A; KR20150021531A

Abstract

A method for monitoring the torque produced by a motor vehicle engine (M), in particular an electric engine comprising: -a step (15, 20) of comparing an estimated or measured value of the torque produced by said engine (CE) with a low limit value (VLIMB) or high limit value (VLIMH) to detect excessive braking (SF) or acceleration (AI) and/or a lack of braking (PF) or acceleration (PM). The method further comprises a step (14, 19) of calculating said low limit value or high limit value (VLIMB, VLIMH), said step of calculating comprising: -subtracting or adding (11, 16) a static error value (εA, εB, %εA, %εB) to a torque value requested by the driver of the vehicle (CC) in order to obtain a low or high intermediate signal (SIB, SIH); and -applying (12, 17), to said intermediate signal, a delay corresponding to a response time of the engine to a torque increase request (TMA) or to a torque decrease request (TMB) expressed by the driver of the vehicle.

Description

System and method for monitoring the torque of a motor vehicle engine

The technical field of the invention is the control systems and more particularly the torque control systems of a motor fitted to a vehicle, for example an electric traction vehicle.

The control of the torque exerted by the engine of a vehicle makes it possible in particular to detect a lack of coherence corresponding to an unsuitability between the torque demanded by the driver and the torque exerted by the engine.

It is known from patent application US 2009/06628 1, a torque monitoring strategy of the engine of an electric vehicle (or hybrid) based on the comparison between a torque setpoint and an estimate of the torque produced by the electric motor. . At low speed, this estimate is made from the position of the rotor and a phase current of the motor. At high speed, it is developed from the power provided by the traction battery.

It is known from patent application US 2005/050965, a strategy for monitoring the torque of the engine of an electric vehicle based on the comparison between a torque setpoint, a first estimate of the torque exerted by the motor, made from the measurement of the motor currents and a second estimation of the torque achieved, based on the engine speed, the power supplied by the traction battery, the losses (mechanical and electrical) and the power consumed by the other consumer bodies than the engine.

Finally, it is known from patent application US 2010/042276, a strategy for monitoring the engine torque of a hybrid vehicle. According to this strategy, it is verified at each instant that the sum of the torques of the vehicle's engines (electrical and thermal) is within an interval calculated from a setpoint of maximum torque and torque that can be exerted by the electric and thermal motors.

In general, the torque monitoring strategies of the state of the art are based on the comparison with a tolerance threshold of the difference between a torque setpoint and one or more estimated torques.

However, these strategies are only adapted to slow variations of torque setpoints. Indeed, during the phases of rapid variation, the slightest phase difference between the torque request and the torque estimate due for example to a normal delay between the torque request and the torque being produced by the motor results in a difference of important couple. This difference may exceed the tolerance threshold in nominal operation.

It therefore appears that these control strategies used during the rapid variation phases of the torque setpoint unexpectedly detect threshold overruns without there necessarily being a torque defect realized by the motor.

An object of the invention is therefore to propose a method of controlling the torque of the motor which can operate in particular during the phases of rapid variation of a torque setpoint.

It is proposed according to one embodiment and implementation of the invention, a method of monitoring the engine torque simp le and easy to implement.

It is also proposed according to an embodiment and implementation of the invention, a detection of a problem of acceleration and / or braking of the vehicle.

The object of the invention is a method for monitoring the torque produced by a motor vehicle engine, in particular an electric motor comprising:

- A step of comparing an estimated or measured torque value made by said motor with a low or high limit value to detect excess braking or acceleration and / or insufficient braking or acceleration. According to a general characteristic, the method further comprises a step of calculating said low or high limit value, said calculation step comprising:

- subtracting or adding to a torque value requested by the driver of the vehicle a static error value to obtain a low or high intermediate signal; and

- the application to said intermediate signal of a delay corresponding to a response time of the engine to a torque increase request or a torque reduction request expressed by the driver of the vehicle.

It is thus expected a comparison of the estimated torque with a low limit or a high limit. Crossing these limits will trigger detection of excess braking or acceleration and / or insufficient braking or acceleration.

Compared to the prior art which merely uses a low or high limit using a fixed threshold, the invention adds in the calculation of the low or high limit the application of a delay. This delay corresponds to a maximum acceptable delay of the motor response in the case of an increase or a decrease in the torque demand.

In this way, limit values are obtained for which a normal engine delay in the event of an increase or a decrease does not trigger a crossing.

According to one characteristic, the method further comprises a step of recognizing an increase or a decrease in the torque demand, and wherein:

comparing said estimated or measured torque value produced by the motor with the low limit value in the case of recognition of an increase in the torque demand, so as to detect an excess of braking and / or an insufficiency of acceleration; and

comparing said estimated or measured torque value made by the motor with the high limit value in the case of recognition of a decrease in the torque demand, so as to detect an excess of acceleration and / or a lack of braking.

The monitoring process is simple. The two low and high limits are not tested in a systematic way. On the contrary, we test the upper limit or the lower limit when the probability that it is exceeded is greater.

According to another characteristic, the calculation step for obtaining a low or high limit value comprises a step of filtering the intermediate signal delayed by a low pass filter having a cutoff pulse representing a dynamics of response of the motor to a request for increase. or decrease in torque.

With the low-pass filtering corresponding to an acceptable dynamics of the motor, it avoids a crossing of the limits due to the dynamics of the engine if it remains within an acceptable range.

According to one embodiment, the calculation step for obtaining the low limit value comprises:

the subtraction of the torque value requested by the driver of the vehicle from a first static error to obtain a low intermediate signal; and

the application to said low intermediate signal of a delay corresponding to a maximum response time of the engine to a request for an increase in torque expressed by the driver of the vehicle.

According to another embodiment, the calculation step for obtaining the high limit value comprises:

- adding to the torque value requested by the driver of the vehicle a second static error to obtain a high intermediate signal; and

- the application to said high intermediate signal of a delay corresponding to a maximum response time of the engine to a torque reduction request expressed by the driver of the vehicle.

The calculations of high or low limit values are similar and very simple.

According to an additional mode of implementation, the recognition step comprises: a high pass filter step of the torque request; and

a comparison step comprising:

a comparison of the filtered torque demand passes high with a first positive threshold to recognize the beginning of a phase of increase in torque demand expressed by the driver of the vehicle; and

a comparison of the filtered torque demand goes high with a second positive threshold to recognize the end of an increase phase of the torque demand, said second positive threshold being lower than said first positive threshold; or

a comparison of the filtered torque demand passes high with a first negative threshold to recognize the beginning of a phase of decrease in the torque demand expressed by the driver of the vehicle; and

a comparison of the filtered torque demand goes high with a second negative threshold to recognize the end of a torque demand reduction phase, said second negative threshold being greater than said first negative threshold.

The detection of a phase of increase or decrease is simple on the one hand and fast on the other hand thanks to the presence of high pass filtering. Using these steps to recognize the beginning and end of the increase and decrease phases, it is possible to determine windows in which the torque increases or decreases respectively. It is then possible to control the engine torque only during these phases of increase and decrease.

The invention also relates to a torque monitoring system realized by a motor vehicle engine, in particular an electric motor comprising:

means for comparing an estimated or measured torque value produced by said motor with a low or high limit value for detecting excess braking or acceleration and / or insufficient braking or acceleration. According to a general characteristic, the system further comprises means for calculating said low or high limit value, said calculation means comprising:

means for subtracting or adding to a torque value requested by the driver of the vehicle a static error value to obtain a low or high intermediate signal; and

means for applying to said intermediate signal a delay corresponding to a response time of the motor to a request for a torque increase or decrease expressed by the driver of the vehicle.

According to one characteristic, the system further comprises means for recognizing an increase or a decrease in the torque demand expressed by the driver of the vehicle, said comparison means comprising:

means configured to compare, in the case of the recognition of an increase in the torque demand, said torque value with the low limit value, so as to detect an excess of braking and / or an insufficiency of acceleration; and

- Means for comparing in the case of the recognition of a decrease in torque demand said torque value with said high limit value, so as to detect an excess of acceleration and / or insufficient braking.

According to another characteristic, the means for calculating said low or high limit value comprises a low-pass filtering means of the delayed intermediate signal having a cut-off pulse representing a dynamic response of the motor to a request for increasing the torque or decreasing the torque expressed by the driver of the vehicle.

According to one embodiment, the calculation means for obtaining the low limit value comprises:

means for subtracting the torque request from a first static error to obtain a low intermediate signal; and means for applying to said low intermediate signal a delay corresponding to the maximum response time of the motor to a request for an increase in torque;

and the calculating means for obtaining the high limit value comprises:

means for adding to the torque request a second static error in order to obtain a high intermediate signal; and

means for applying to said high intermediate signal a delay corresponding to the maximum response time of the motor to a torque reduction request.

Other objects, features and advantages will become apparent upon reading the following description given solely as a non-limitative example and with reference to the accompanying drawings, in which:

FIG. 1 illustrates a mode of implementation of a method of monitoring the pair according to the invention; and

- Figures 2 to 5 illustrate block diagrams of a torque monitoring system according to one embodiment of the invention.

The torque monitoring method of FIG. 1 is a control method that monitors a motor M, for example the electric motor of a motor vehicle, to detect anomalies in the torque produced by this motor M.

The realized torque is the result of a demand for DC torque transmitted to the motor M. The motor M must then realize a torque in accordance with this request for DC torque. The demand for DC torque may, for example, be expressed by the driver of the vehicle or may also be expressed by a computer receiving vehicle running conditions and a speed reference from the driver.

Step 10 of the monitoring method is to detect whether the demand for DC torque is in an increase phase or whether the DC torque demand is in a decrease phase. In other words, step 10 of the method is a step of recognizing a phase of increasing or decreasing the DC torque setpoint.

Step 10 of the monitoring method includes a high pass filtering sub-step 1 of the DC torque request to obtain the FCC high pass filtered torque request. This step is for example performed by a high pass filter whose transfer function is:

s wc

where wc is the cutoff pulse of the high pass filter in rad.s ^"1 and s is the Laplace variable.

Step 10 comprises on the one hand two sub-steps 2, 3 for detecting a phase of increasing the requested torque CC:

a comparison step 2 of the high pass filtered torque request FCC with a first positive threshold SI to recognize the start of a phase of increasing the demand for DC torque. Thus according to step 2, the start of an increase phase is recognized if the filtered torque setpoint FCC is greater than the threshold S1; and

a comparison step 3 of the high pass filtered torque request FCC with a second positive threshold S2 to recognize the end of a phase of increasing the torque demand. Thus, according to step 3, the end of an increase phase is recognized if the filtered torque setpoint FCC is below the threshold S2.

The positive threshold S2 is lower than the first positive threshold SI, and the thresholds S1 and S2 are sufficiently far apart. Thus, it avoids recognitions and cessations of untimely recognition.

Several threshold values are possible for example in the range from 0 to 100 Nm.s- ^1, for example Sl = 20 Nm.s- ¹ and S2 = 15 Nm.s- ¹ .

According to one embodiment, step 10 further comprises sub-steps 2 and 3, two further sub-steps:

a first additional sub-step 4 which is a step for recognizing the end of a phase of increasing the torque demand. It includes the comparison of the derivative of the couple asked CC with the null value. According to this first additional step, the end of an increase phase is recognized if the derivative of the requested torque CC is negative;

a second additional sub-step 5 which is a step for recognizing the end of a phase of increasing the torque demand. It includes measuring the length of time the demand for DC torque ceases to increase. That is, the time during which the derivative of the requested torque CC takes a negative or zero value. According to this second substep, the end of an increase phase is recognized if the derivative of the requested torque CC takes a negative or zero value for at least a duration TZA, for example equal to 0.05 second, which is a parameter for adjusting the process monitoring.

Step 10 further comprises two sub-steps 6, 7 for detecting a phase of decreasing the requested torque CC:

the comparing step 6 of the filtered high FCC torque request with a first negative threshold C 1 to recognize the beginning of a phase of decreasing the torque demand. Thus according to step 6, the beginning of a decrease phase is recognized if the filtered setpoint is below the threshold C 1; and

a comparison step 7 of the high pass filtered torque request FCC with a second negative threshold C2 to recognize the end of a phase of decrease in the torque demand. Thus, according to step 7, the end of a decrease phase is recognized if the filtered setpoint FCC is greater than the threshold C2.

The second negative threshold C2 is greater than the first negative threshold C 1, and the thresholds C 1 and C 2 are sufficiently far apart. Thus, it avoids recognitions and cessations of untimely recognition. A plurality of threshold values are possible for example in the range from 0 to -. 100 Nm ^{s -1} for example C2 = -45 Nm s. ^'1 and C l = -55 Nm s ^"1..

According to one embodiment, step 10 further comprises sub-steps 6 and 7, two additional sub-steps 8 and 9: - Step 8 is a step to recognize the end of a phase of decreasing the torque demand. It includes comparing the derivative of the requested pair CC with the null value. According to step 8, the end of a decrease phase is recognized if the derivative of the requested torque CC is positive;

- Step 9 is a step to recognize the end of a phase of decreasing the torque demand. It includes measuring the length of time the CC torque request ceases to decrease. That is, the time during which the derivative of the requested torque CC takes a positive value or zero. According to step 9, the end of a decrease phase is recognized if the derivative of the requested torque CC takes a positive or zero value for at least one duration TZB, for example equal to 0.05 second, which is a parameter for adjusting the process monitoring.

Thus, at the end of the recognition step 10, it is indicated by a boolean variable AUG, the detection of an increase phase and by a DIM boolean variable, the detection of a decrease phase. The process then continues along three branches.

According to a first branch (bottom), neither an increase phase nor a decrease phase is detected. That is, DIM = 0 and AUG = 0, the monitoring method then continues with a new acquisition of the requested torque CC and a new recognition step.

According to a second branch (on the right), an increase phase is detected. That is, AUG = 1, the monitoring method continues with steps 14 and 15.

According to a third branch (on the left), a decrease phase is detected. That is, DIM = 1, the monitoring method continues with steps 19 and 20.

According to the second branch (right), the step 14 of the monitoring method is a calculation step to obtain a low limit value VLIMB, this limit value being used for a comparison in step 15. Step 14 comprises calculation steps 1 1, 12 and 13.

Step 1 1 is a subtraction step according to which the value of a first static error εΑ is subtracted from the DC torque request to obtain a low intermediate signal SIB.

This static error can be expressed as a static error in absolute value, a static error as a percentage of the torque demand, or both. In general, the formula to be applied to obtain the SIB signal is:

where εΑ is the static error and% εΑ is the static error expressed as a percentage of the DC setpoint.

For example, the following values are used: εΑ = 5 Nm and% εΑ = 6. These values are determined during a characterization of the motor M during which acceptable maximum static error values εΑ and% εΑ are determined for a given value. normal operation of the engine during a phase of increasing the requested torque CC.

Step 12 is a step of applying a delay of a duration TMA on the low intermediate signal SIB. The duration TMA is a setting parameter of the monitoring method, for example the TMA = 0.1 seconds. This value is determined during a characterization of the motor M during which it is determined, taking into account the duration of estimation or measurement, the maximum acceptable duration of response of the motor to an increase in the torque setpoint.

Step 13 is a low pass filtering step of the low signal SIB after it has been delayed by the duration TMA. For this purpose, a PBA pass filter having a cut-off pulse wca is used. As an exemplary embodiment, the Laplace transform transfer function of the PBA filter is:

1

s

1 +

wca The wca pulse is a setting parameter of the monitoring method, for example wca = 5 rad. s ^"1. This value is determined in a characterization of the motor M during which it is determined, taking into account the duration of the estimation or measurement, the minimum acceptable dynamic engine response to an increase in setpoint couple.

Thus, at the end of step 14, the low limit VLIMB is equal to the signal SIB determined in step 1 1 to which a delay has been applied according to step 12 and low pass filtering according to step 13. According to another embodiment, the low limit value VLIMB is equal to the signal SIB determined in step 11, which has been applied a delay according to step 12, the filtering step 13 being suppressed.

Step 15 of the method consists in comparing an estimated or measured measured torque CE with the value VLIMB and the null value.

According to one embodiment, the estimated or measured measured torque CE may be directly measured by a torque measuring sensor or may according to another embodiment be calculated by an estimation means (i.e. a calculator) from other measurement parameters such as the currents consumed by the electric motor according to different calculation methods well known to those skilled in the art.

Step 15 comprises receiving an estimated or measured torque value CE made by the motor M.

During step 15, the following four conditions are monitored:

- condition 1: recognition of an increase in AUG torque demand;

- condition 2: torque value CE is lower than the low value VLIMB;

- condition 3: the torque value CE is greater than or equal to the zero value; and

- condition 4: the torque value CE is less than the zero value; If and only if conditions 1 to 3 are observed, a lack of acceleration is detected. This information is then indicated via a PM boolean value that takes the value 1.

If and only if conditions 1, 2 and 4 are observed then an excess of braking is detected. This information is then indicated via a Boolean value SF which takes the value 1.

According to the third block (left), the step 19 of the monitoring method is a calculation step to obtain a high limit value VLIMH, this limit value being used for a comparison in step 20.

Step 19 includes calculation steps 16, 17 and 18.

Step 16 is an addition step in which the value of a first static error εΒ is added to the DC torque request to obtain a high intermediate signal SIH.

This static error can be expressed as a static error in absolute value, a static error as a percentage of the torque demand, or both. In general, the formula to be applied to obtain the SIH signal is:

where εΒ is the static error and% εΒ is the static error expressed as a percentage of the DC setpoint.

For example, the following values are used: εΒ = 5 Nm and% εΒ = 6. These values are determined during a characterization of the motor M during which acceptable maximum static error values εΒ and% εΒ are determined for a given value. normal operation of the engine during a phase of reduction of the requested torque

CC .

Step 17 is a step of applying a delay of a duration TMB on the high intermediate signal SIH. The duration TMB is a setting parameter of the monitoring method, for example TMB = 0.1 seconds. This value is determined during a characterization of the motor M during which it is determined, taking into account the estimation or measurement time, the maximum acceptable motor response time to a decrease in the torque setpoint.

Step 1 8 is a low pass filtering step of the high signal

SIH after it has been delayed by the TMB duration. For this purpose, a PBB pass filter with a web break pulse is used. As an exemplary embodiment, the transfer function in the form of

Laplace of the PBB filter is:

1

1 + ^ - web

The web pulse is a setting parameter of the monitoring process, for example wcb = 5 rad. s ^"1. This value is determined in a characterization of the motor M during which it is determined, taking into account the duration of the estimation or measurement, the minimum acceptable dynamic engine response to a decrease in the setpoint couple.

Thus, at the end of step 19, the high limit VLIMH is equal to the signal SIH determined in step 16 to which a delay according to step 17 has been applied and a low pass filtering according to step 1 8 According to another embodiment, the high limit value VLIMH is equal to the signal SIH determined in step 16 which has been applied a delay according to step 17, the filtering step 1 8 being suppressed.

The step 20 of the monitoring method consists in comparing an estimated or measured CE measured torque with the VLIMH value and the zero value.

According to one embodiment, the estimated or measured measured torque CE may be directly measured by a torque measurement sensor or may according to another embodiment be calculated by an estimation means (ie a computer) from other parameters. such as the currents consumed by the electric motor according to different calculation methods well known to those skilled in the art.

Step 20 comprises receiving an estimated or measured torque value CE made by the motor M. During step 20, the following four conditions are monitored:

- condition 1: recognition of a decrease in the DIM torque demand;

- condition 2: torque value CE is greater than the high value VLIMH;

- condition 4: the torque value CE is less than the zero value;

If and only if conditions 1 to 3 are observed, an excess of acceleration is detected. This information is then indicated via a boolean value AI which takes the value 1.

If and only if conditions 1, 2 and 4 are observed then a lack of braking is detected. This information is then indicated via a Boolean value PF which takes the value 1.

FIG. 2 illustrates an embodiment of a SYSCOM system for monitoring the torque produced by a motor M.

The SYSCOM system includes a first high pass filter block 1 and a second torque monitor block 2. The SYSCOM system receives the estimated or measured torque CE and the DC torque request.

Block 1 will filter the DC torque request to obtain the FCC signal corresponding to the filtered high pass torque setpoint. The blo c 1 performs step 1 of FIG. The blo c 1 corresponds to a high pass filter whose parameter is its cutoff pulse wc.

The monitoring block 2 receives the estimated or measured torque CE, the request for DC torque and the filtered high pass setpoint FCC.

Figure 3 illustrates an embodiment of the monitoring block 2.

The monitoring block 2 comprises a first monitoring block 21 in the case of the decrease of the DC setpoint and a second monitoring block 22 in the case of the increase of the DC setpoint. Block 21 receives the estimated or measured torque CE, the torque request CC and the high pass filtered set point FCC and derives the two Boolean values PM and SF. Block 21 performs steps 2, 3, 4, 5, 14 and 15 of the monitoring method of FIG.

Block 22 receives the estimated or measured torque CE, the torque request CC and the high pass filtered set point FCC and deduces the two boolean values AI and PF. Block 21 performs steps 6, 7, 8, 9, 19 and 20 of the monitoring method of FIG.

FIG. 4 illustrates one embodiment of the monitoring block 21.

The monitoring block 21 comprises a recognition block of a torque demand increase phase 211 and a detection block 212 of an excess of braking and / or insufficient acceleration of the motor M.

Block 211 recognizes a phase of increasing the demand for DC torque. It receives the DC torque request and the high pass filtered set point FCC and derives the AUG boolean value indicative of the recognition of an increase phase. For this, block 211 also receives the parameters S1, S2, and TZA and performs steps 2 to 5 of FIG.

The block 211 thus comprises means for comparing the high pass filtered torque request FCC, with the thresholds S1 and S2. The block 211 also comprises means for calculating the derivative of the torque demand CC, means for comparing the derivative of the torque demand with the zero value and means for measuring the duration during which the derivative of the demand of torque takes the null value.

According to these operations, the block 211 is configured to provide a Boolean value AUG which takes the value 1 indicating the recognition of an increase phase of the request for DC torque or which takes the value 0 indicating the non-recognition of a phase of increasing the demand for DC torque.

Block 212 receives the estimated or measured torque CE, the torque request CC and the boolean value AUG. He deduces a value IEC 60050 - International Electrotechnical Vocabulary - Details for IEV number 701-23-8 Signaling and distribution - Non - pollutant Boolean PM indicating the detection of a lack of acceleration and a Boolean value SF indicating the detection of excess braking It also receives the parameters εΑ,% εΑ, TMA and wca and perform steps 14 and 15 of FIG.

Blo c 212 thus comprises means for calculating a low limit value VLIMB and means for comparing the estimated or measured torque CE with the value VLIMB.

More precisely, the block 212 comprises means for subtracting a static error εΑ and / or% εΑ to calculate an intermediate signal SIB, means for applying a delay TMA and filtering means not passing. For example, the PBA lowpass pulse filter wca.

Block 212 further comprises means for monitoring the four following conditions:

- condition 1: recognition of an increase in AUG torque demand;

- condition 2: estimated or measured torque value CE is lower than the low value VLIMB;

- condition 3: the EC or measured torque value is greater than or equal to the zero value; and

- condition 4: the measured or measured torque value is less than the zero value.

These monitoring means are, by way of example embodiment, of the means of logical combinations of these four conditions which can be expressed in the following mathematical format:

- condition 1: AUG = 1;

- condition 2: CE <VLIMB;

- condition 3: CE> 0 or CE = 0; and

- condition 4: CE <0.

FIG. 5 illustrates an embodiment of the monitoring block 22.

The monitoring block 22 comprises a recognition block for a torque demand reduction phase 221 and a block of detection 222 of excess acceleration and / or insufficient braking of the motor M.

Block 221 recognizes a phase of decreasing the demand for DC torque. It receives the DC torque request and the high pass filtered set point FCC and deduces the Boolean value DIM indicating the recognition of a decrease phase. For this purpose, the block 22 1 also receives the parameters C 1, C 2, and TZB and performs steps 6 to 9 of FIG.

The block 22 1 therefore comprises means for comparing the high pass filtered torque request FCC, with the thresholds C 1 and C 2. Block 221 also comprises means for calculating the derivative of the torque demand CC, means for comparing the derivative of the torque demand with the zero value and means for measuring the duration during which the derivative of the torque request takes the null value.

According to these operations, the block 221 is configured to provide a Boolean value DIM which takes the value 1 indicating the recognition of a phase of decrease of the request for torque CC or which takes the value 0 indicating the non-recognition of a phase of reducing the demand for DC torque.

Block 222 receives the estimated or measured torque CE, the torque request CC and the boolean value DIM. It deduces a Boolean value PF indicating the detection of a braking failure and a Boolean value AI indicating the detection of an excess of acceleration. It also receives the parameters εΒ,% εΒ, TMB and web and perform steps 19 and 20 of FIG.

The blo c 222 thus comprises means for calculating a low limit value VLIMH and means for comparing the estimated or measured torque CE with the value VLIMH.

More precisely, the block 222 comprises means for adding a static error εΒ and / or% εΒ to calculate an intermediate signal SIH, means for applying a delay TMB and filtering means not passing. For example, the web break pulse pass PBB filter. Block 222 further comprises means for monitoring the following four conditions:

- condition 1: recognition of a decrease in the DIM torque demand;

- condition 2: torque value CE is greater than the high value VLIMH;

- condition 4: the torque value CE is less than the zero value;

- condition 1: DIM = 1;

- condition 2: EC> VLIMH;

- condition 3: CE> 0 or CE = 0; and

- condition 4: CE <0.

As an exemplary embodiment, the SYSCOM control system can be integrated in an electronic control unit of the engine M. The blocks 1, 2, 21, 22, 222, 221, 21 1, 212 of the SYSCOM control system can for example in the form of software modules, or for some of them in the form of logic circuits. Setting one of the Boolean values AI, PF, SF, PM can trigger a safety measurement on the motor M by a central computer or the electronic control unit of the motor M.

Claims

1. A method of monitoring the torque produced by a motor vehicle engine (M), in particular an electric motor, comprising:

a step of comparing (15, 20) an estimated or measured torque value produced by said motor (CE) with a low limit value (VLIMB) or a high value (VLIMH) for detecting an excess of braking (SF) or of acceleration (AI) and / or insufficient braking (PF) or acceleration (PM),

characterized in that the method further comprises a step of calculating (14, 19) said low or high limit value (VLIMB, VLIMH), said computing step comprising:

the subtraction or addition (1 1, 1 6) to a torque value requested by the driver of the vehicle (CC) of a static error value (εΑ, εΒ,% εΑ,% εΒ) to obtain a low or high intermediate signal (SIB, SIH), and

- Applying (12, 17) to said intermediate signal a delay corresponding to a response time of the engine to a torque increase request (TMA) or a torque reduction request (TMB) expressed by the driver. of the vehicle.

The method of claim 1, further comprising a step of recognizing (10) an increase or decrease in the torque demand (CC), and wherein:

comparing (15) said estimated or measured torque value made by the motor (CE) with the low limit value (VLIMB) in the case of recognizing an increase in the torque demand, so as to detect an excess braking (SF) and / or insufficient acceleration (PM); and

comparing (20) said estimated or measured torque value made by the motor (CE) with the high limit value (VLIMH) in the case of recognizing a decrease in the torque demand, so as to detect an excess of acceleration (AI) and / or insufficient braking (PF).

The method according to claim 1 or 2, wherein said calculating step (14, 19) for obtaining a low or high limit value (VLIMB, VLIMH) comprises a step of filtering (13, 18) the intermediate signal delayed by a low pass filter (PBA, PBB) having a cutoff pulse (wca, web) representing a dynamic response of the motor to a request for increase or decrease in torque.

The method of claim 1 to 3, wherein the computing step (14) to obtain the low limit value (VLIMB) comprises:

- the subtraction (1 1) of the torque value requested by the driver of the vehicle (CC) of a first static error (εΑ,% εΑ) to obtain a low intermediate signal (SIB); and

- the application to said low intermediate signal (SIB) of a delay (12) corresponding to a maximum response time of the engine to a request for a torque increase (TMA) expressed by the driver of the vehicle.

The method of claim 1 to 4, wherein the computing step (19) for obtaining the high limit value (VLIMH) comprises:

- addition (16) to the torque value requested by the vehicle driver (CC) of a second static error (εΒ,% εΒ) to obtain a high intermediate signal (SIH); and

- the application to said intermediate high signal (SIH) of a delay (17) corresponding to a maximum response time of the engine to a torque reduction request (TMB) expressed by the driver of the vehicle.

The method of claim 2 to 5, wherein the recognition step (10) comprises:

a filter step (1) passes high the torque request (CC); and

a comparison step (2, 3, 6, 7) comprising:

a comparison (2) of the high pass filtered torque request (FCC) with a first positive threshold (SI) for recognizing the beginning of a phase of increase in torque demand expressed by the driver of the vehicle; and a comparison (3) of the high pass filtered torque request (FCC) with a second positive threshold (S2) for recognizing the end of an increase phase of the torque demand, said second positive threshold (S2) being less than said first positive threshold (SI); or

a comparison (6) of the high pass filtered torque request (FCC) with a first negative threshold (C 1) to recognize the beginning of a phase of decrease in the torque demand expressed by the driver of the vehicle; and

a comparison (7) of the high pass filtered torque request (FCC) with a second negative threshold (C2) for recognizing the end of a torque demand reduction phase, said second negative threshold (C2) being greater than at said first negative threshold (C l).

7. Monitoring system (SYSCOM) of the torque produced by a motor vehicle engine (M), in particular an electric motor comprising:

means for comparing (212, 222) an estimated or measured torque value produced by said motor (CE) with a low or high limit value (VLIMB, VLIMH) for detecting an excess of braking (SF) or of acceleration (AI) and / or insufficient braking (PF) or acceleration (PM),

characterized in that the system further comprises means (12, 222) for calculating said low or high limit value (VLIMB, VLIMH), said calculating means (212, 222) comprising:

means for subtracting (1 1) or adding (16) to a torque value requested by the driver of the vehicle (CC) a static error value (εΑ, εΒ,% εΑ,% εΒ) for obtain a low or high intermediate signal (SIB, SIH), and

- means for applying (12, 17) to said intermediate signal a delay corresponding to a response time of the engine to a request for a torque increase or decrease (TMA, TMB) expressed by the driver of the vehicle.

8. System according to claim 7, further comprising means for recognizing an increase or a decrease (21 1, 221) in the torque demand expressed by the driver of the vehicle, said comparison means (212, 222 ) including:

means (212) configured to compare, in the case of recognition of an increase in the torque demand, said torque value (CE) with the low limit value (VLIMB), so as to detect an excess of braking (SF ) and / or insufficient acceleration (PM); and

means (222) for comparing, in the case of recognition of a decrease in the torque demand, said torque value (CE) with said high limit value (VLIMH), so as to detect an excess of acceleration (AI) and / or insufficient braking (PF).

9. System according to claim 8, wherein the calculation means (212, 222) of said low or high limit value comprises a low pass filtering means (PBA, PBB) of the delayed intermediate signal having a cut-off pulse (wca, web) representing a dynamics of engine response to a request for torque increase or torque reduction expressed by the driver of the vehicle.

10. System according to one of claims 7 to 9, wherein:

the calculation means (222) for obtaining the low limit value comprises:

means for subtracting (1 1) the torque request (CC) from a first static error (εΑ,% εΑ) to obtain a low intermediate signal; and

means for applying (12) on said low intermediate signal (SIB) a delay corresponding to the maximum response time of the motor (M) to a torque increase request (TMA);

the calculation means (2 12) for obtaining the high limit value comprises: means for adding (16) to the torque request (CC) a second static error (εΒ,% εΒ) acceptable for obtaining a high intermediate signal; and

means for applying (17) said high intermediate signal (SIH), a delay corresponding to the maximum response time of the motor (M) to a torque reduction request (TMB).