REGULATION OF A VEHICLE'S EXHAUST GAS TEMPERATURE UPFRONT OF A CATALYTIC CONVERTER

Abstract

A control method is implemented in a vehicle comprising a thermal engine whose operating speed is determined by a first setpoint representing a supply air torque, and which produces exhaust gases that feed a catalytic converter exhaust system. This method includes a step (10-30) in which a second setpoint is determined, representing a reserve of air torque intended to heat the catalytic converter and intended to be combined with the first setpoint, and a first exhaust gas temperature upstream of the catalytic converter is regulated according to this second setpoint to promote the achievement of a second chosen exhaust gas temperature in the catalytic converter. Figure 3

Description

Title of the invention: REGULATION OF EXHAUST GAS TEMPERATURE OF A VEHICLE UPFRONT OF A CATALYTIC CONVERTER Technical field of the invention

[0001] The invention relates to vehicles comprising at least one thermal engine producing exhaust gases feeding a catalytic exhaust line, and more specifically the regulation of at least one exhaust gas temperature upstream of such a catalyst. State of the art

[0002] Certain vehicles, possibly of the automobile type, include a powertrain (or PWM) comprising at least one internal combustion engine that produces exhaust gases feeding a catalytic converter exhaust system. It should be noted that the invention also relates to hybrid PWMs and therefore also includes a non-internal combustion engine (for example, electric).

[0003] As those skilled in the art know, for an exhaust catalytic converter to function optimally, its internal temperature (resulting at least from the passage of exhaust gases) must reach a predefined temperature range depending on its internal arrangement and the catalytic components it contains. It has therefore been proposed to implement in the vehicles described above a method for rapidly increasing the exhaust gas temperature by increasing the amount of air in the air / fuel mixture supplying the internal combustion engine, so as to reduce the amount of pollutant emissions released into the outside air.

[0004] This process (sometimes called "enthalpic boost" – a rapid increase in enthalpy) generally consists, when the operating speed of the internal combustion engine is determined by a first setpoint representing a supply air torque, of determining a second setpoint representing a reserve of air torque intended to heat the catalyst and which is intended to be combined with the first setpoint. This reserve of air torque results in what is called a "torque structure loop" and therefore a demand for a reduction in ignition timing to meet the current torque demand determined for the internal combustion engine.

[0005] While such a process certainly allows the catalyst to operate optimally and very quickly, it frequently happens that the internal temperature of the catalyst exceeds the upper limit of its predefined temperature range. In this case, at least some of the catalytic components may be degraded, causing a decrease in the catalyst's ability to reduce pollutant emissions.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] In particular, it proposes for this purpose a regulation method, on the one hand, intended to be implemented in a vehicle comprising a thermal engine having in operation a regime based on a first setpoint representing a torque of supply air, and producing exhaust gases supplying an exhaust line with a catalyst, and, on the other hand, comprising a step in which a second setpoint is determined, representing a reserve of air torque intended to heat the catalyst and intended to be combined with the first setpoint.

[0008] This regulation method is characterized by the fact that in its step a first temperature of the exhaust gases upstream of the catalyst is regulated according to the second setpoint in order to promote obtaining a second chosen temperature of the exhaust gases in the catalyst.

[0009] Thus, the probability that the internal temperature of the catalyst exceeds the upper bound of its predefined temperature range is (almost) zero, and therefore there is no longer any risk of degradation of at least some of the catalyst's catalytic components due to the realization of a very rapid increase in exhaust gas temperature phase.

[0010] The regulation method according to the invention may include other features which may be taken separately or in combination, and in particular:

[0011] - in its step, after obtaining the second chosen temperature, one can regulate the second setpoint so that the exhaust gases in the catalyst have a temperature less than or equal to the second chosen temperature;

[0012] - in its step, a proportional type regulation of the can be carried out first temperature based on a difference between the second chosen temperature and a third exhaust gas temperature measured in the catalyst, and a coefficient which is a function of this difference and between predefined minimum and maximum values;

[0013] - in the presence of the last option, in its stage, when the drive machine Thermal control is achieved using a heat transfer fluid with a fourth temperature. We can determine, firstly, a first value representing a nominal air torque reserve intended to heat the catalyst when the coefficient equals the predefined maximum value, depending on the operating conditions and initial setpoint, and secondly, a second value representing an air torque reserve for implementing a function intended to heat the catalyst when the coefficient is equal to the predefined minimum value, depending on the regime, fourth temperature and first setpoint, and a third value representing a chosen physical quantity, then the second setpoint can be determined as a function of the first and second values ​​determined and the coefficient;

[0014] - in the presence of the last sub-option, in its step, when the minimum values and maximum predefined are respectively equal to zero and one, we can determine the second setpoint by performing a sum of a first product of the first value determined by the coefficient and a second product of the second value determined by a fourth value equal to one minus the coefficient;

[0015] - also in the presence of the last sub-option, in its step, one can determine the second value by calculating the difference between a fifth value, based on the regime, fourth temperature and first setpoint, and the third value;

[0016] - also in the presence of the last sub-option, in its step, the magnitude physics can be chosen from an estimated energy accumulated in the catalyst over a chosen period and atmospheric pressure outside the vehicle.

[0017] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing the regulation method of the type presented above in a vehicle comprising a thermal engine having in operation a regime as a function of a first setpoint representing a torque of supply air, and producing exhaust gases supplying an exhaust line with a catalyst, to regulate at least a first temperature of the exhaust gases upstream of the catalyst.

[0018] The invention also proposes a regulation device, on the one hand, intended to equip a vehicle comprising a thermal engine having in operation a regime based on a first setpoint representing a torque of supply air, and producing exhaust gases supplying an exhaust line with a catalyst, and, on the other hand, comprising at least one processor and at least one memory arranged to perform the operations consisting of determining a second setpoint, representing a reserve of air torque intended to heat the catalyst and intended to be combined with the first setpoint.

[0019] This regulation device is characterized by the fact that its processor and memory are also arranged to perform the operations consisting of triggering a regulation of a first temperature of the exhaust gases upstream of the catalyst according to the second setpoint in order to promote obtaining a second chosen temperature of the exhaust gases in the catalyst.

[0020] The invention also proposes a vehicle, possibly of the automobile type, comprising, on the one hand, a thermal engine having in operation a regime as a function of a first setpoint representing a torque of supply air, and producing exhaust gases supplying an exhaust line with a catalyst, and, on the other hand, a regulation device of the type of that presented above. Brief description of the figures

[0021] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a vehicle comprising a control device according to the invention, and a purely thermal powertrain and supervisory computer,

[0023] [Fig.2] schematically and functionally illustrates an example of the realization of a a supervisory computer comprising a control device according to the invention, and

[0024] [Fig.3] schematically illustrates an example of an algorithm implementing an regulation method according to the invention. Detailed description of the invention

[0025] The invention aims in particular to propose a method of regulation, and an associated regulation device, intended to allow regulation of at least a first temperature Tl of the exhaust gases upstream of a catalyst CL of an exhaust line LE associated with the thermal engine MMT of a vehicle V.

[0026] In what follows, vehicle V is considered, by way of non-limiting example, to be of the automobile type. For example, it is a car, as illustrated in [Fig. 1]. However, the invention is not limited to this type of vehicle. It relates to any type of vehicle (land, sea (or river), or air) comprising a powertrain with a powertrain including at least one internal combustion engine producing exhaust gases that feed a catalytic converter exhaust system.

[0027] Furthermore, in what follows, by way of non-limiting example, we consider that the powertrain is purely thermal (and therefore comprises only at least one thermal power unit). However, the invention is not limited to this type of powertrain. It also relates to hybrid powertrains, and therefore to powertrains comprising at least one thermal power unit and at least one non-thermal power unit (for example, electric).

[0028] Figure 1 schematically represents a vehicle V comprising a purely thermal powertrain (and therefore comprising at least one thermal powertrain associated with a catalytic converter exhaust system) CL) and supervised by a CS supervisory computer, and a DR control device according to the invention.

[0029] As illustrated, the transmission chain also includes, here, a drive shaft AM, a coupling device DC, a gearbox BV, and a transmission shaft AT.

[0030] The operation of the transmission chain (and therefore of the GMP) is supervised by the CS supervision computer.

[0031] The MMT thermal drive unit comprises a crankshaft (not shown) which is fixedly attached to the motor shaft AM in order to drive the latter (AM) in rotation. This MMT thermal drive unit is designed to be coupled to the gearbox BV via the DC coupling device. Furthermore, it (MMT) is designed to provide engine torque to move the vehicle V, as instructed by the CS supervisory control unit.

[0032] This DC coupling device delivers motor torque for at least one TRI set of drive wheels of the vehicle V when it is in a position at least partially coupled (or closed) and therefore when it couples the thermal drive machine MMT to the primary shaft AP of the gearbox BV.

[0033] For example, the TRI train can be located in the front PVV section of vehicle V. It is preferably, and as illustrated, coupled to the AT driveshaft via a differential (here, the front one) DV. But in a variant, this TRI train could be the one referenced TR2, which is located in the rear PRV section of vehicle V.

[0034] Also, for example, the DC coupling device can be a clutch (single or double). But it could also be a torque converter or a dog clutch.

[0035] The gearbox can optionally be automated. In this case, it can be of the so-called "dual-clutch (or DCT)" type. But this is not mandatory.

[0036] In the illustrated example, which is not exhaustive, the crankshaft of the MMT internal combustion engine is also coupled to a belt CC, which is itself coupled to an alternator-starter AD that is electrically powered by a service battery BS (and which can also recharge the latter (BS)). Thus, the alternator-starter AD can supply torque to the belt CC, which can then supply this torque to the crankshaft.

[0037] The MMT thermal power unit is also associated with an LE exhaust line with a CL catalyst, which it supplies with exhaust gas during operation. This CL catalyst functions optimally when its internal temperature (resulting at least from the passage of exhaust gases) is within a predefined temperature range depending on its internal arrangement and the catalytic components it comprises.

[0038] It should also be noted that in operation the MMT thermal engine has a so-called engine speed rm which is a function of a first representative setpoint cl of a supply air pair. For example, this first setpoint cl can be provided by the CS supervisory computer.

[0039] As mentioned above, the invention proposes in particular a regulation method intended to allow the regulation of at least a first temperature Tl of the exhaust gases upstream of the catalyst CL of the exhaust line LE of the vehicle V.

[0040] For example, this first temperature Tl could be that of the exhaust gases exiting the exhaust valves of the MMT internal combustion engine. However, this is not mandatory. Indeed, the first temperature Tl could be that of the exhaust gases at any point between the exhaust valve outlets and a zone located just before (and therefore upstream of) the inlet of the CL catalyst.

[0041] This (regulation) method can be implemented at least partially by the DR regulation device (illustrated at least partially in Figures 1 and 2), which for this purpose comprises at least one PR1 processor, for example a digital signal processor (or DSP), and at least one MD memory. This DR regulation device can therefore be implemented in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software").

[0042] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the control process. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0043] In the example illustrated, but not limited to, Figures 1 and 2, the DR control device is part of the CS supervisory control unit. However, this is not mandatory. Indeed, the DR control device could comprise its own dedicated control unit, which could then be coupled to the CS supervisory control unit, or it could be part of another control unit embedded in the vehicle V and performing at least one other function in the vehicle (V).

[0044] As illustrated non-limitingly in [Fig.3], the (regulation) method according to the invention includes a step 10-30 which is implemented each time a phase of very rapid increase in the temperature of the exhaust gases is triggered so that the CL catalyst can operate optimally as quickly as possible ((almost) without risk of degradation of its catalytic components), so as to reduce the amount of polluting emissions released into the outside air.

[0045] Step 10-30 of the process includes a substep 10 in which a second setpoint c2 is determined (for example, by the control device DR). This second setpoint represents a reserve of air torque intended to heat the catalyst CL and is intended to be combined with the first setpoint cl. For example, this combination could consist of adding the first cl and second c2 setpoints. However, this is not mandatory. Indeed, more complex combinations using at least one weighting coefficient can be considered.

[0046] Step 10-30 of the process also includes a substep 20 in which the first temperature Tl of the exhaust gases upstream of the catalyst CL is regulated (for example the DR control device triggers a regulation of) according to the second setpoint c2 (determined in substep 10) to promote obtaining a second chosen temperature T2 of the exhaust gases in the catalyst CL.

[0047] It will be understood that this second chosen temperature T2 is within the predefined temperature range in which the operation of the CL catalyst is optimal. This second chosen temperature T2 may be predefined or variable depending on atmospheric conditions and / or the estimated condition of the CL catalyst.

[0048] Thanks to this regulation of the initial temperature Tl, the probability that the internal temperature of the CL catalyst will exceed the upper limit of its predefined temperature range is (virtually) zero. Consequently, there is (virtually) no longer any risk of degradation of at least some of the catalytic components of the CL catalyst, and therefore the latter (CL) is no longer at risk of a reduction in its capacity to decrease pollutant emissions due to a very rapid increase in exhaust gas temperature.

[0049] It should be noted that this first regulation (of the first temperature Tl) is done by generating (for example by the regulation device DR) messages including a first instruction for regulating the first temperature TL

[0050] For example, and as illustrated, but not limited to, in [Fig. 3], step 10-30 of the process may also include a substep 30 in which, after obtaining the second selected temperature T2, the second setpoint c2 can be regulated (for example, the control device DR can trigger regulation of) so that the exhaust gases in the catalyst CL have a temperature that is less than or equal to the second selected temperature T2. This second regulation, this time of the second setpoint c2, is intended to ensure that the internal temperature of the catalyst CL remains within its predefined temperature range once the first regulation has enabled the second selected temperature T2 to be obtained.

[0051] It will be noted that this second regulation (of the second setpoint c2) is done by the generation (for example by the regulation device DR) of messages including a second instruction for regulating the second setpoint c2.

[0052] For example, in substep 20 of step 10-30, proportional regulation of the first temperature T1 can be performed (for example, the DR control device can be triggered). In this case, this first regulation is based on the difference dT between the second selected temperature T2 and a third temperature T3 of the exhaust gases measured in the catalyst CL, and on a coefficient cd which is a function of this difference dT and falls between predefined minimum cdmin and maximum cdmax values. We then have dT = T2 - T3, and cd = f(dT).

[0053] For example, a first lookup table establishing a correspondence between temperature differences and coefficients can be used to determine the coefficient cd that corresponds to the current temperature difference dT. This first lookup table (or map) can be obtained in the laboratory or during tests during the development of a vehicle similar to vehicle V. It can be stored in the DR control device.

[0054] It should be noted that instead of using a first correspondence table such as this, one could at least use a mathematical formula giving the evolution of the coefficient cd as a function of the difference dT in progress.

[0055] It should also be noted that other types of first regulation known to those skilled in the art can be considered, and in particular a first regulation of the integral type.

[0056] It should also be noted that the MMT thermal drive machine can be subjected to thermal control by a heat transfer fluid (generally water, possibly with an additive) having a fourth temperature T4. In this case, in substep 20 of step 10-30, one (for example, the DR control device) can begin by determining first v1 and second v2 values ​​useful for the first control.

[0057] The first value vl represents a nominal air torque reserve intended to heat the catalyst CL when the coefficient cd is equal to the predefined maximum value cdmax. It is determined as a function of the engine speed rm and the first setpoint cl.

[0058] For example, a second lookup table tc2, establishing a correspondence between engine speed pairs and initial setpoints and initial values, can be used to determine the first value vl that corresponds to the current engine speed rm and initial setpoint cl. This second lookup table (or map) tc2 can be obtained in the laboratory or during testing while developing a vehicle similar to vehicle V. It can be stored in the DR control device.

[0059] It should be noted that instead of using a second tc2 correspondence table, one could at least use a mathematical formula giving the evolution of the first value vl as a function of the engine speed rm and first setpoint cl in progress.

[0060] The second value v2 represents a reserve of air torque to implement a function designed to heat the catalyst CL (very rapidly) when the coefficient cd is equal to the predefined minimum value cdmin. It can be determined as a function of the engine speed rm, the fourth temperature T4, the first setpoint cl, and a third value v3 which represents a chosen physical quantity. For example, this function could be the enthalpy boost function.

[0061] Also, for example, to determine the second value v2, we can use third tc3 and fourth tc4 lookup tables.

[0062] The third lookup table tc3 establishes a correspondence between engine speed pairs and initial setpoints, and sixth values ​​to determine the sixth value v6, which corresponds to the current engine speed rm and initial setpoint cl. It should be noted that this third lookup table tc3 can be identical to the second lookup table tc2. This third lookup table (or map) tc3 can be obtained in the laboratory or during testing while developing a vehicle similar to vehicle V. It can be stored in the DR control unit.

[0063] It should also be noted that instead of using a third tc3 correspondence table, one could at least use a mathematical formula giving the evolution of the sixth value v6 as a function of the engine speed rm and first setpoint cl in progress.

[0064] The fourth lookup table tc4 establishes a correspondence between fourth temperatures and seventh values ​​to determine the seventh value v7, which corresponds to the current fourth temperature T4. This fourth lookup table (or map) tc4 can be obtained in the laboratory or during testing while developing a vehicle similar to vehicle V. It can be stored in the DR control device.

[0065] It should be noted that instead of using a fourth tc4 correspondence table, one could at least use a mathematical formula giving the evolution of the seventh value v7 as a function of the fourth temperature T4 in progress.

[0066] For example, the second value v2 can be equal to the difference between a fifth value v5 and the third value v3, i.e., v2 = v5 - v3. The fifth value v5 is, for example, a function of the engine speed rm, the fourth temperature T4, and the first setpoint cl. As an example, the fifth value v5 can be equal to the product of the sixth v6 and seventh v7 values, i.e., v5 = v6*v7.

[0067] Then, in substep 20 of step 10-30, one (for example the DR control device) can determine the second setpoint c2 as a function of the first vl and second v2 values ​​determined and the coefficient cd.

[0068] It should also be noted that the predefined minimum (cdmin) and maximum (cdmax) values ​​of the coefficient cd can be equal to zero (0) and one (1), respectively. In this case, in substep 20 of step 10-30, the second setpoint c2 can be determined (for example, by the DR control device) by summing the first pl and second p2 products, i.e., c2 = pl + p2. The first product pl is equal to the multiplication of the first determined value vl by the coefficient cd, i.e., pl = vl*cd. The second product p2 is equal to the multiplication of the second determined value v2 by a fourth value v4 equal to one minus the coefficient cd, i.e., p2 = v2*v4 = v2*(l - cd). We then have c2 = [vl*cd] + [v2*(l - cd)].

[0069] In other words, the second setpoint c2 is determined here by calculating the centroid between the first v1 and second v2 determined values, weighted respectively by coefficients equal to cd and (1 - cd). However, other, more complex formulas can be used to determine the second value v2 as a function of the first v1 and second v2 determined values ​​and the determined coefficient cd.

[0070] For example, in substep 20 of step 10-30, one (for example, the DR control device) can use a physical quantity (which is represented by the third value v3) chosen from the estimated energy accumulated in the catalyst CL over a chosen time period (for example, a complete catalysis cycle) and the atmospheric pressure outside the vehicle V (measured in situ or provided by a database).

[0071] It will also be noted, as illustrated non-limitingly in [Fig.2], that the CS supervisory computer (or the dedicated computer of the DR control device) can also include a mass memory MM1, in particular to store the engine speed rm, the first setpoint cl, the fourth temperature T4, the third temperature T3 and any second chosen temperature T2 and chosen physical quantity, as well as any intermediate data involved in all its calculations and processing.Furthermore, this CS supervisory computer (or the dedicated computer of the DR control device) may also include an IE input interface for receiving at least the engine speed rm, the first setpoint cl, the fourth temperature T4, the third temperature T3, and any optional second selected temperature T2 and chosen physical quantity, for use in calculations or processing, possibly after shaping and / or demodulating and / or amplifying them, in a manner known per se, by means of a PR2 digital signal processor. In addition, this CS supervisory computer (or the dedicated computer of the DR control device) may also include an IS output interface, in particular. to deliver each message including a first instruction to regulate the first temperature T1, and each possible message including a second instruction to regulate the second setpoint c2.

[0072] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the regulation process described above to regulate at least the first temperature Tl of the exhaust gases upstream of the catalyst CL of the exhaust line LE of the vehicle V.

Claims

Demands

1. A control method for a vehicle (V) comprising a thermal power machine (TMM) having in operation a regime as a function of a first setpoint representing a torque of supply air, and producing exhaust gases supplying an exhaust line (LE) with a catalyst (CL), said method comprising a step (10-30) in which a second setpoint is determined, representing a reserve of air torque intended to heat said catalyst (CL) and intended to be combined with said first setpoint, characterized in that in said step (10-30) a first temperature of said exhaust gases upstream of said catalyst (CL) is regulated as a function of said second setpoint to promote obtaining a second chosen temperature of said exhaust gases in said catalyst (CL).

2. The method according to claim 1, characterized in that in said step (10-30), after obtaining said second selected temperature, said second setpoint is regulated so that said exhaust gases have in said catalyst (CL) a temperature less than or equal to said second selected temperature.

3. Method according to claim 1 or 2, characterized in that in said step (10-30) a proportional type regulation of said first temperature is carried out as a function of a difference between said second chosen temperature and a third temperature of said exhaust gas measured in said catalyst (CL), and of a coefficient as a function of said difference and between predefined minimum and maximum values.

4. A method according to claim 3, characterized in that in said step (10-30), in the presence of a thermal power machine (CPM) subjected to thermal control by a heat transfer fluid having a fourth temperature, i) a first value representing a nominal air torque reserve intended to heat said catalyst (CL) when said coefficient is equal to said predefined maximum value, as a function of said operating conditions and first setpoint, and ii) a second value representing an air torque reserve for implementing a function intended to heat said catalyst (CL) when said coefficient is equal to the said predefined minimum value, according to the said regime, fourth temperature and first setpoint, and a third value representing a chosen physical quantity, then the said second setpoint is determined according to the said first and second determined values ​​and the said coefficient.

5. Method according to claim 4, characterized in that in said step (10-30), when said predefined minimum and maximum values ​​are respectively equal to zero and one, said second setpoint is determined by performing a sum of a first product of said first value determined by said coefficient and a second product of said second value determined by a fourth value equal to one less said coefficient.

6. Method according to claim 4 or 5, characterized in that in said step (10-30) said second value is determined by calculating a difference between a fifth value, a function of said regime, fourth temperature and first setpoint, and said third value.

7. A method according to any one of claims 4 to 6, characterized in that in said step (10-30) said physical quantity is chosen from an estimated energy accumulated in said catalyst (CL) over a chosen time period and at an atmospheric pressure outside said vehicle (V).

8. Product computer program comprising a set of instructions which, when executed by processing means, is suitable for implementing the regulation method according to any one of claims 1 to 7, in a vehicle (V) comprising a thermal engine (TEM) having in operation a regime as a function of a first setpoint representative of a supply air torque, and producing exhaust gases supplying an exhaust line (LE) with a catalyst (CL), to regulate at least a first temperature of said exhaust gases upstream of said catalyst (CL).

9. A control device (CD) suitable for equipping a vehicle (V) comprising a thermal engine (TEM) having, in operation, an operating speed based on a first setpoint representing a supply air torque, and producing exhaust gases supplying an exhaust line (EL) with a catalytic converter (CL), said control device (CD) comprising at at least one processor (PR1) and at least one memory (MD) arranged to perform the operations of determining a second setpoint, representative of a reserve of air torque intended to heat said catalyst (CL) and intended to be combined with said first setpoint, characterized in that said processor (PR1) and memory (MD) are further arranged to perform the operations of triggering a regulation of a first temperature of said exhaust gases upstream of said catalyst (CL) as a function of said second setpoint to promote obtaining a second chosen temperature of said exhaust gases in said catalyst (CL).

10. Vehicle (V) comprising a thermal power machine (MMT) having in operation a regime as a function of a first setpoint representative of a supply air torque, and producing exhaust gases supplying an exhaust line (LE) with a catalyst (CL), characterized in that it further comprises a regulation device (DR) according to claim 9.

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