ESTIMATION OF AIR PRESSURE IN AN INTAKE DIVIDER OF A VEHICLE ENGINE

Abstract

An estimation method is implemented in a vehicle comprising a heat engine and an intake manifold comprising at least one inlet suitable for receiving supercharging air under a measured pressure, and outlets suitable for supplying distributed air to this heat engine. This method comprises a step (10-30) in which an air pressure in the intake manifold is estimated using as an upper limit of the latter a saturation pressure upstream of the estimated inlet by applying to the measured pressure a filter having an action on the latter which is a function of the amplitude of current variations of this measured pressure. Figure 3

Description

Title of the invention: ESTIMATION OF THE AIR PRESSURE IN AN INTAKE DISTRIBUTOR OF A VEHICLE THERMAL ENGINE Technical field of the invention

[0001] The invention relates to vehicles comprising a thermal engine supplied with air distributed by an intake distributor receiving supercharging air, and more precisely to the estimation of the air pressure in the intake distributors of such vehicles. State of the art

[0002] Certain vehicles, possibly of the automobile type, comprise an intake distributor (or manifold) comprising at least one inlet suitable for receiving supercharging air and outlets suitable for supplying distributed air to this thermal engine (for example at the cylinder heads).

[0003] In these vehicles, the control of the operation of the thermal engine is carried out in particular as a function of the air pressure inside the intake manifold. The latter therefore comprises a pressure sensor responsible for measuring this air pressure. However, as it may happen that this pressure sensor is faulty or that the measured air pressure does not reach the computer controlling the thermal engine, the air pressure in the intake manifold is also estimated in the vehicles by calculation, independently of the air pressure measured by the pressure sensor. An estimated air pressure is thus available at all times which can be substituted for the measured air pressure if necessary.

[0004] The estimated air pressure is generally a function of the derivative of the ideal gas equation, general thermodynamic equations and a model of air flow(s) entering the intake manifold and air flow(s) leaving the intake manifold. In this case, the accuracy of the air pressure estimation is directly linked to the quality of representation of the model used. Thus, as long as this model has not been recalibrated by the learning strategies for controlling the heat engine, the estimated air pressure may differ significantly from the measured air pressure.

[0005] In order to avoid excessively large differences between the estimated and measured air pressures, a conventional solution consists of saturating the estimated air pressure with the air pressure which is measured by another pressure sensor upstream of the inlet of the intake manifold which receives the supercharging air from the vehicle's turbocharger. It will be understood that saturation consists of using as an upper limit of the estimated air pressure the air pressure measured by the other pressure sensor. This other pressure sensor is generally installed upstream of the valve (often butterfly type) which controls access to the aforementioned inlet. Indeed, this valve being upstream of the inlet and creating a pressure drop, it is considered that in the vast majority of cases, the pressure downstream of the valve (and therefore in the intake manifold) must not be higher than the air pressure measured upstream of the valve.

[0006] This saturation of the air pressure estimated by the air pressure measured upstream of the supercharging inlet of the intake manifold is satisfactory whenever the air flow is stabilized, but it can be limiting in a transient phase. This is for example the case when the measured air pressure suddenly becomes subject to a depression due to the sudden opening of the valve (transient phase), and this depression is detected with a time delay relative to the estimated air pressure due to the fact that it has been filtered by a signal processing chain. It will be understood that in such a situation, the estimated air pressure is limited (or saturated) later than it should be by the depression of the measured air pressure, which significantly degrades its accuracy.

[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0008] It proposes in particular for this purpose an estimation method, on the one hand, intended to estimate an air pressure in an intake distributor comprising at least one inlet suitable for receiving supercharging air under a measured pressure, and outlets suitable for supplying distributed air to a heat engine of a vehicle, and, on the other hand, comprising a step in which the air pressure is estimated using as an upper limit of the latter a saturation pressure upstream of the inlet.

[0009] This estimation method is characterized by the fact that in its step the saturation pressure is estimated by applying to the measured pressure a filtering having an action on the latter which is a function of an amplitude of current variations of the measured pressure.

[0010] Thanks to this variable action of the filtering on the measured pressure, an estimated saturation pressure is available which attenuates, or even eliminates, the transient, unforeseen and time-delayed variations of the measured pressure, and therefore in a transient phase the estimated air pressure does not become saturated later than it should be by transient variations of the measured air pressure, which makes it possible to avoid degrading the accuracy of the estimated air pressure.

[0011] The estimation method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0012] - in its step, the greater the amplitude of the current variations of the measured pressure is the more important, the less the filtering action can be on the measured pressure;

[0013] - in its step, the filtering can use a filtering coefficient which is a function of the less than a difference between a current atmospheric pressure outside the vehicle and the measured pressure;

[0014] - in the presence of the last option, in its step, the filtering coefficient can be also a function of at least one parameter chosen from a gradient of evolution of a position of a valve controlling access of the supercharging air to the inlet, an operating instruction of a control actuator of a turbocharger equipping the vehicle and supplying the supercharging air, and a ratio between the measured pressure of the supercharging air and the current atmospheric pressure;

[0015] - also in the presence of the last option, in its step, the pressure of its estimated saturation at a time t can be equal to the sum of the filtering coefficient multiplied by the measured pressure and the saturation pressure estimated at a time t-1 preceding t multiplied by a difference between the number one and the filtering coefficient;

[0016] - in its step, the estimated air pressure can be a function of a derivative of a ideal gas equation, general thermodynamic equations and a modeling of air flow(s) entering the intake manifold and air flow(s) leaving the intake manifold.

[0017] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing an estimation method of the type presented above, in a vehicle comprising a heat engine and an intake distributor comprising at least one inlet capable of receiving supercharging air under a measured pressure, and outlets capable of supplying distributed air to the heat engine, in order to estimate an air pressure in this intake distributor.

[0018] The invention also proposes an estimation device, on the one hand, intended to estimate an air pressure in an intake distributor comprising at least one inlet suitable for receiving supercharging air under a measured pressure, and outlets suitable for supplying distributed air to a heat engine of a vehicle, and, on the other hand, comprising at least one processor and at least one memory arranged to carry out the operations consisting of estimating the air pressure using as an upper limit of the latter a saturation pressure upstream of the inlet.

[0019] This estimation device is characterized by the fact that its processor and memory are arranged to carry out the operations consisting of estimating the saturation pressure by applying to the measured pressure a filtering having an action on the latter which is a function of an amplitude of current variations of the measured pressure.

[0020] The invention also provides a vehicle, possibly of the automobile type, and comprising, on the one hand, a heat engine and an intake distributor comprising at least one inlet suitable for receiving supercharging air under a measured pressure and outlets suitable for supplying distributed air to this heat engine, and, on the other hand, an estimation device of the type presented above. Brief description of the figures

[0021] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of an intake manifold coupled to a heat engine and a turbocharger of a vehicle, an engine computer associated with the heat engine, and an estimation device according to the invention,

[0023] [Fig.2] schematically and functionally illustrates an exemplary embodiment of an engine calculator comprising an exemplary embodiment of an estimation device according to the invention, and

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

[0025] The invention aims in particular to propose an estimation method, and an associated estimation device DD, intended to allow an estimation of the air pressure pae in an intake manifold RA coupled to a thermal engine MT and a turbocharger TC of a vehicle.

[0026] In the following, it is considered, by way of non-limiting example, that the vehicle is of the automobile type. For example, it is a car. But the invention is not limited to this type of vehicle. It relates in fact to any type of vehicle comprising a transmission chain with a powertrain (or GMP) comprising at least one thermal motor (or engine) supplied with air by an intake distributor (or manifold) receiving supercharging air from a turbocharger. Thus, it relates to land vehicles (utility vehicles, camper vans, minibuses, coaches, trucks, road machinery, construction machinery, agricultural machinery, tracked machinery, trains and trams, for example), aircraft and boats.

[0027] Furthermore, it should be noted that the GMP can be of the all-electric or hybrid type.

[0028] [Fig. 1] schematically shows an estimation device DD according to the invention and an intake distributor RA connected at least to a thermal engine MT of a vehicle and to a supply duct also connected to a turbocharger TC of this vehicle. As illustrated, the operation of the thermal engine MT is controlled by an engine computer CM which is itself supervised by a GMP supervision computer (not illustrated).

[0029] The intake distributor RA comprises at least a first inlet El which is suitable for receiving supercharging air from the turbocharger TC, and outlets S1 which are suitable for supplying distributed air to the thermal engine MT at the level of each of its cylinders (for example at the level of the cylinder heads). The first inlet El is here connected to a downstream end of the supply duct which is connected to the turbocharger TC.

[0030] In the example illustrated non-limitingly in [Fig.l], the supply duct comprises a first valve VI (for example of the butterfly type), which controls access to the first inlet El, and a first pressure sensor Cl installed upstream of the first valve VI and responsible for measuring the pressure pasm of the supercharging air which comes from the turbocharger TC. It will be noted that in an alternative embodiment the supply duct (with the first valve VI and the first pressure sensor Cl) could be part of the intake manifold RA.

[0031] It is considered here that the measured pressure pasm of the supercharging air, delivered by the first pressure sensor C1, has been filtered by a signal processing chain of the latter (C1). But this filtering could be carried out downstream of the first pressure sensor C1, and for example in the engine computer CM.

[0032] The intake distributor RA comprises a second pressure sensor C2 responsible for measuring the param pressure of the air it contains.

[0033] It will be noted that in the example illustrated non-limitingly in [Fig. 1] the intake distributor RA also comprises second E2 and third E3 inlets whose accesses are respectively controlled by second V2 and third V3 valves. The second valve V2 here forms part of a circuit for recovering hydrocarbon vapors contained in the vehicle's fuel tank (or "canister"), and the third valve V3 here forms part of an exhaust gas recirculation circuit (or EGR ("Exhaust Gas Recirculation")).

[0034] As mentioned above, the invention proposes in particular an estimation method intended to allow the estimation (by calculation) of the air pressure pae in the intake manifold RA of the vehicle. It is recalled that this estimated air pressure pae is intended to be substituted for the measured air pressure param (from the second pressure sensor C2), when the latter (C2) is faulty or when the measured air pressure param does not reach the engine computer CM which controls the operation of the thermal engine MT.

[0035] The (estimation) method can be implemented at least partially by the estimation device DD (illustrated at least partially in FIGS. 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one memory MD. This estimation device DD can therefore be implemented in the form of a combination of circuits or electrical or electronic components (or "hardware") and software modules (or "software"). For example, this could be a microcontroller.

[0036] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the estimation method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0037] In the example illustrated non-limitingly in Figures 1 and 2, the estimation device DD is part of the engine computer CM. But this is not obligatory. Indeed, the estimation device DD could comprise its own dedicated computer, which is then coupled to the engine computer CM, for example.

[0038] As illustrated non-limitingly in [Fig. 3], the (estimation) method, according to the invention, comprises a step 10-30 which is implemented during each phase of use of the thermal engine MT.

[0039] Step 10-30 of the method comprises a sub-step 20 in which one (for example the estimation device DD) estimates a saturation pressure pse upstream of the first inlet El by applying to the measured pressure pasm of the supercharging air a filtering having an action on the latter (pasm) which is a function of the amplitude of the current variations of this measured pressure pasm.

[0040] It will be understood that the action (or effect) of the filtering varies depending on the operating situation: namely a stabilized regime (very low amplitude of the variations in the measured pressure pasm) or a transient regime (high amplitude of the variations in the measured pressure pasm) of the air flow circulating in the intake distributor RA). Thus, the saturation pressure pse is “allowed to live” in order to have very little filtering effect and therefore very little deviation from the measured pressure pasm when the latter (pasm) is expected to evolve (such as for example when the turbocharger TC is in operation), while the rest of the time the effect (or action) of the filtering on the measured pressure pasm is greatly increased so that the estimated saturation pressure pse has a significant deviation from the measured pressure pasm and therefore to attenuate the variations in the latter (pasm).

[0041] Step 10-30 of the method also comprises a sub-step 30 in which one (for example the estimation device DD) estimates the air pressure pae in the intake distributor RA using as the upper limit of the latter (pae) the saturation pressure pse estimated in sub-step 20. Each estimated air pressure pae is transmitted by means of a message to the machine computer CM so that it uses it to control the operation of the heat engine MT.

[0042] This variable action (or effect) of the filtering on the measured pressure pasm allows to have an estimated saturation pressure pse which attenuates, or even eliminates, transient, unforeseen and time-delayed variations in the measured pressure pasm (such as, for example, during a depression of the latter (pasm) due to the sudden opening of the first valve VI). Thus, in a transient phase the estimated air pressure pae is not limited (or saturated) later than it should be by transient variations in the measured air pressure pasm, which avoids degrading its accuracy. And, in the phases of stabilized regime or the phases of supercharging, the securing of the estimated air pressure pae is maintained by the saturation of the latter (pae) by the estimated saturation pressure pse which differs little, or even very little, from the measured pressure pasm due to the (very) reduced action of the filtering.

[0043] For example, in sub-step 30 of step 10-30 the estimated air pressure pae may be a function of the derivative of the ideal gas equation, general thermodynamic equations and a modeling of air flow(s) entering the intake distributor RA and air flow rates leaving the intake distributor RA (via its outlets SI), as is well known to those skilled in the art. It will be noted that in the case of the intake distributor RA illustrated non-limitingly in [Fig.l], the modeling takes into account three air flow rates entering the intake distributor RA respectively via the first E1, second E2 and third E3 inlets.

[0044] Also for example, in sub-step 20 of step 10-30 the greater the amplitude of current variations of the measured pressure pasm, the less the action of the filtering can be significant on the measured pressure pasm of the supercharging air. Different laws of variation of the action of the filtering as a function of the amplitude of the current variations of the measured pressure pasm can be envisaged, and in particular a decreasing linear law or inverse quadratic (decreasing) or even inverse exponential (decreasing).

[0045] Also for example, in sub-step 20 of step 10-30 the filtering can use a filtering coefficient cf which is a function at least of the difference dp between the current atmospheric pressure patm outside the vehicle and the measured pressure pasm of the supercharging air (i.e. dp = patm - pasm). In this case, when the measured pressure pasm reaches (or begins to exceed) a value which is close to the current atmospheric pressure patm, this means that we are entering a supercharging phase and therefore that the effect (or action) of the filtering must be significantly attenuated.

[0046] It will be noted, as illustrated non-limitingly in [Fig.3], that step 10-30 may comprise a preliminary sub-step 10 in which one (for example the estimation device DD) can determine the filtering coefficient cf at least as a function of the difference dp.

[0047] Also for example, in sub-step 10 of step 10-30 the filtering coefficient cf can also be a function of at least one parameter which is chosen from the gradient of evolution of the position of the first valve VI (controlling the access of the supercharging air to the first inlet El), an operating instruction of a control actuator of the turbocharger TC (which supplies the supercharging air), and the ratio rp between the measured pressure pasm of the supercharging air and the current atmospheric pressure patm (i.e. rp = pasm / patm).

[0048] When the filtering coefficient cf is a function of the difference dp and at least one parameter, it can, for example, be determined in a correspondence table (or mapping) stored in a memory (for example of the estimation device DD) and establishing a correspondence between multiplets of values ​​of difference dp and parameter(s) and values ​​of filtering coefficient.

[0049] Also for example, in sub-step 20 of step 10-30 the estimated saturation pressure pse(t) at a time t can be equal to the sum of the filtering coefficient cf multiplied by the measured pressure pasm of the supercharging air and the estimated saturation pressure pse(tl) at a time t-1 preceding t multiplied by the difference between the number one and the filtering coefficient cf, i.e. pse(t) = (cf*pasm) + (pse(tl)*(l - cf)). But other formulas using the filtering coefficient cf and the measured pressure pasm can be used to estimate the saturation pressure pse(t).

[0050] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the engine computer CM (or the computer of the estimation device DD) can also comprise a mass memory MME, in particular for storing the measured pressure pasm, the possible current atmospheric pressure patm, and the possible gradient of evolution of the position of the first valve VI and / or the possible operating instruction of the turbocharger control actuator TC and / or the possible ratio rp, as well as possible intermediate data involved in all its calculations and processing.Furthermore, this engine computer CM (or the computer of the estimation device DD) can also comprise an input interface IE for receiving at least the measured pressure pasm, the possible current atmospheric pressure patm, and the possible gradient of evolution of the position of the first valve VI and / or the possible operating setpoint of the turbocharger control actuator TC and / or the possible ratio rp, to use them in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2. In addition, this engine computer CM (or the computer of the estimation device DD) can also comprise an output interface IS, in particular for delivering a message containing the estimated air pressure pae.

[0051] 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 electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the estimation method described above to estimate the air pressure pae in the intake manifold RA coupled to the thermal engine MT of a vehicle.

Claims

Claims

1. Method for estimating an air pressure in an intake manifold (RA) comprising i) at least one inlet (El) suitable for receiving supercharging air under a measured pressure, and ii) outlets (SI) suitable for supplying distributed air to a heat engine (MT) of a vehicle, said method comprising a step (10-30) in which said air pressure is estimated using as an upper limit thereof a saturation pressure upstream of said inlet (El), characterized in that in said step (10-30) said saturation pressure is estimated by applying to said measured pressure a filtering having an action on the latter which is a function of an amplitude of current variations of said measured pressure.

2. Method according to claim 1, characterized in that in said step (10-30) the greater said amplitude of the current variations, the less important said filtering action is on said measured pressure.

3. Method according to claim 1 or 2, characterized in that in said step (10-30) said filtering uses a filtering coefficient which is a function at least of a difference between a current atmospheric pressure outside said vehicle and said measured pressure.

4. Method according to claim 3, characterized in that in said step (10-30) said filtering coefficient is also a function of at least one parameter chosen from a gradient of evolution of a position of a valve (VI) controlling access of said supercharging air to said inlet (El), an operating instruction of a control actuator of a turbocharger (TC) equipping said vehicle and supplying said supercharging air, and a ratio between said measured pressure of the supercharging air and said current atmospheric pressure.

5. Method according to claim 3 or 4, characterized in that in said step (10-30) said saturation pressure estimated at a time t is equal to the sum of said filtering coefficient multiplied by said measured pressure and the saturation pressure estimated at a time t-1 preceding t multiplied by a difference between the number one and said filtering coefficient.

6. Computer program product comprising a set of instructions which, when executed by processing means, is capable of putting implementing the estimation method according to one of claims 1 to 5, in a vehicle comprising a heat engine (MT) and an intake manifold (RA) comprising i) at least one inlet (El) capable of receiving supercharging air under a measured pressure, and ii) outlets (SI) capable of supplying distributed air to said heat engine (MT), to estimate an air pressure in said intake manifold (RA).

7. Estimation device (DD) for estimating an air pressure in an intake manifold (RA) comprising i) at least one inlet (El) suitable for receiving supercharging air under a measured pressure, and ii) outlets (SI) suitable for supplying distributed air to a heat engine (MT) of a vehicle, said estimation device (DD) comprising at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of estimating said air pressure using as an upper limit thereof a saturation pressure upstream of said inlet (El), characterized in that said processor (PR1) and memory (MD) are arranged to carry out the operations consisting of estimating said saturation pressure by applying to said measured pressure a filtering having an action on the latter which is a function of an amplitude of current variations of said measured pressure.

8. Vehicle comprising a heat engine (MT) and an intake manifold (RA) comprising i) at least one inlet (El) capable of receiving supercharging air under a measured pressure, and ii) outlets (SI) capable of supplying distributed air to said heat engine (MT), characterized in that it further comprises an estimation device (DD) according to claim 7.

9. Vehicle according to claim 8, characterized in that it is of the automobile type.

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