ESTIMATING AIR PRESSURE IN AN INTAKE DISPENSER OF A VEHICLE INTERNAL COMBUSTION ENGINE

Abstract

An estimation method is implemented in a vehicle comprising an internal combustion engine and an intake manifold including at least one inlet for receiving charge air at a measured pressure, and outlets for supplying distributed air to this internal combustion engine. This method includes a step (10-30) in which an air pressure in the intake manifold is estimated using as its upper limit a saturation pressure upstream of the estimated inlet by applying a filter to the measured pressure whose effect on the measured pressure is a function of the amplitude of variations during this measured pressure. Figure 3

Description

Title of the invention: ESTIMATION OF AIR PRESSURE IN AN INTAKE DISPENSER OF A VEHICLE INTERNAL COMBUSTION ENGINE Technical field of the invention

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

[0002] Some vehicles, possibly of the motor vehicle type, include an intake distributor (or manifold) comprising at least one inlet for receiving boost air and outlets for supplying distributed air to this internal combustion engine (for example at the cylinder heads).

[0003] In these vehicles, the operation of the internal combustion engine is controlled, in particular, by the air pressure inside the intake manifold. The manifold therefore includes a pressure sensor responsible for measuring this air pressure. However, since this pressure sensor may fail or the measured air pressure may not reach the engine control unit (ECU), 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. This provides an estimated air pressure at any given time, 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 law, general thermodynamic equations, and a model of the air flow rate(s) entering and exiting the intake manifold. In this case, the accuracy of the air pressure estimate is directly related to the quality of the representation of the model used. Thus, until this model has been recalibrated by the learning strategies of the internal combustion engine control system, the estimated air pressure may differ significantly from the measured air pressure.

[0005] To avoid excessive discrepancies between the estimated and measured air pressures, a common solution is to saturate the estimated air pressure with the air pressure measured by another pressure sensor upstream of the intake manifold inlet, which receives the boost air from the vehicle's turbocharger. It will be understood that saturation involves using the upper limit The estimated air pressure is the air pressure measured by the other pressure sensor. This other pressure sensor is generally installed upstream of the valve (often a butterfly valve) that controls access to the aforementioned inlet. Because this valve is located upstream of the inlet and creates 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) should not exceed the air pressure measured upstream of the valve.

[0006] This saturation of the estimated air pressure by the air pressure measured upstream of the intake manifold's boost inlet is satisfactory whenever the airflow is stabilized, but it can be limiting during a transient phase. This is the case, for example, when the measured air pressure suddenly drops due to the abrupt opening of the valve (transient phase), and this drop is detected with a time delay relative to the estimated air pressure because 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 drop in 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] In particular, it proposes 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 boost 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 the 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 which has an action on the latter which is a function of an amplitude of variations during the measured pressure.

[0010] Thanks to this variable action of the filtering on the measured pressure, we have an estimated saturation pressure which attenuates, or even eliminates, 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 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 features which may be taken separately or in combination, and in particular:

[0012] - in its stage, the greater the amplitude of the ongoing variations in the measured pressure is important, the less important the effect of the filtering can be on the measured pressure;

[0013] - in its step, the filtering can use a filtering coefficient that is a function of less than a difference between the 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 function of at least one parameter chosen from a gradient of evolution of a position of a valve controlling an access of the boost air to the inlet, an operating setpoint of an actuator piloting a turbocharger equipping the vehicle and supplying the boost air, and a ratio between the measured pressure of the boost air and the current atmospheric pressure;

[0015] - also in the presence of the last option, in its stage, the pressure of its The 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 equations of thermodynamics and a modeling of air flow(s) entering the intake distributor and air flow(s) exiting the intake distributor.

[0017] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for 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 suitable for receiving boost air under a measured pressure, and outlets suitable for 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 boost air under a measured pressure, and outlets suitable for supplying distributed air to a thermal engine of a vehicle, and, on the other hand, comprising at least one processor and at least one memory arranged to perform the operations consisting of estimating the air pressure using as the 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 perform the operations of estimating the saturation pressure by applying to the measured pressure a filtering which has an action on the latter which is a function of an amplitude of variations during the measured pressure.

[0020] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a heat engine and an intake distributor including at least one inlet suitable for receiving boost 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 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 the embodiment of an intake distributor coupled to a heat engine and a turbocharger of a vehicle, an engine control unit associated with the heat engine, and an estimation device according to the invention,

[0023] [Fig.2] schematically and functionally illustrates an example of an embodiment of an engine computer comprising an example of an 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 provide an estimation method, and an associated estimation device DD, intended to allow an estimation of the air pressure pae in an intake distributor RA coupled to a thermal engine MT and a turbocharger TC of a vehicle.

[0026] In what follows, the vehicle is considered, by way of non-limiting example, to be of the automobile type. For example, a car. However, the invention is not limited to this type of vehicle. It relates to any type of vehicle comprising a powertrain (or powertrain) including at least one internal combustion engine supplied with air by an intake manifold receiving boost air from a turbocharger. Thus, it relates to land vehicles (commercial vehicles, motorhomes, minibuses, coaches, trucks, road maintenance vehicles, construction equipment, agricultural machinery, tracked vehicles, 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] Figure 1 schematically represents an estimation device DD according to the invention and an intake manifold RA connected to at least one internal combustion engine MT of a vehicle and to a supply duct also connected to a turbocharger TC of that vehicle. As illustrated, the operation of the internal combustion engine MT is controlled by an engine control unit CM, which is itself monitored by a powertrain control unit (not shown).

[0029] The intake manifold RA comprises at least one first inlet El, which is designed to receive charge air from the turbocharger TC, and outlets S1, which are designed to supply distributed air to the internal combustion engine MT at each of its cylinders (for example, at the cylinder heads). The first inlet El is connected to a downstream end of the supply duct that is connected to the turbocharger TC.

[0030] In the example illustrated, but not limited to, in [Fig. 1], 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 boost pressure pasm of the charge air coming from the turbocharger TC. It should 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 assumed here that the measured boost air pressure pasm, delivered by the first pressure sensor Cl, has been filtered by a signal processing chain of the latter (Cl). But this filtering could be carried out downstream of the first pressure sensor Cl, and for example in the engine control unit CM.

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

[0033] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the intake manifold RA also includes second E2 and third E3 inlets, the access to which is controlled respectively by second V2 and third V3 valves. The second V2 valve is part of a circuit for recovering hydrocarbon vapors contained in the vehicle's fuel tank (or "canister"), and the third V3 valve is part of an exhaust gas recirculation (or EGR ("Exhaust Gas Recirculation") circuit.

[0034] As mentioned above, the invention notably proposes an estimation method for estimating (by calculation) the air pressure pae in the vehicle's intake manifold RA. It should be noted that this estimated air pressure pae is intended to replace 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 control unit CM, which controls the operation of the internal combustion engine MT.

[0035] The (estimation) method can be implemented at least partially by the estimation device DD (illustrated at least partially in Figures 1 and 2), which for this purpose comprises at least one processor PR1, for example a digital signal processor (or DSP), 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 MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the estimation 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.

[0037] In the example illustrated, but not limited to, in Figures 1 and 2, the DD estimation device is part of the CM engine control unit. However, this is not mandatory. Indeed, the DD estimation device could comprise its own dedicated control unit, which is then coupled to the CM engine control unit, 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 MT thermal engine.

[0039] Step 10-30 of the process includes a substep 20 in which a saturation pressure pse upstream of the first inlet El is estimated (for example by the estimation device DD) by applying to the measured pressure pasm of the boost air a filtering having an action on the latter (pasm) which is a function of the amplitude of the variations during this measured pressure pasm.

[0040] It will be understood that the action (or effect) of the filtering varies according to the operating situation: namely, a stabilized regime (very small amplitude of variations in the measured pressure pasm) or a transient regime (large amplitude of variations in the measured pressure pasm) of the airflow circulating in the intake distributor RA). Thus, the saturation pressure pse is allowed to remain constant in order to have very little filtering effect and therefore very little difference from the measured pressure pasm when the latter (pasm) is expected to change (such as when the turbocharger TC is operating), while at other times 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 difference from the measured pressure pasm and thus to attenuate the variations of the latter (pasm).

[0041] Step 10-30 of the process also includes a substep 30 in which the air pressure pae in the intake distributor RA is estimated (for example by the estimation device DD) using as the upper limit of the latter (pae) the saturation pressure pse estimated in substep 20. Each estimated air pressure pae is transmitted by means of a message to the machine computer CM so that it can use it to control the operation of the internal combustion engine MT.

[0042] This variable action (or effect) of the filtering on the measured pressure pasm allows Having an estimated saturation pressure (pse) attenuates, or even eliminates, transient, unforeseen, and time-lag variations in the measured pressure (pasm) (such as during a drop in 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), thereby preventing a degradation of its accuracy. Furthermore, in steady-state or supercharged phases, the safety of the estimated air pressure (pae) is maintained by the saturation of the latter (pae) by the estimated saturation pressure (pse), which differs little, if at all, from the measured pressure (pasm) due to the (very) limited action of the filter.

[0043] For example, in substep 30 of step 10-30, the estimated air pressure pae can be a function of the derivative of the ideal gas law, general thermodynamic equations, and a model of the air flow(s) entering the intake manifold RA and the air flow(s) exiting the intake manifold RA (through its outlets SI), as is well known to those skilled in the art. It should be noted that in the case of the intake manifold RA illustrated, but not limited to, in [Fig. 1], the model takes into account three air flow rates entering the intake manifold RA through the first E1, second E2, and third E3 inlets, respectively.

[0044] Also, for example, in substep 20 of step 10-30, the greater the amplitude of the ongoing variations in the measured pressure pasm, the less significant the effect of the filtering can be on the measured pressure pasm of the charge air. Different laws governing the variation of the filtering effect as a function of the amplitude of the ongoing variations in the measured pressure pasm can be considered, including a decreasing linear, inverse quadratic (decreasing), or inverse exponential (decreasing) law.

[0045] Also, for example, in substep 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 charge air (i.e., dp = patm - pasm). In this case, when the measured pressure pasm reaches (or begins to exceed) a value close to the current atmospheric pressure patm, this means that a boost phase is entering and therefore the effect (or action) of the filtering must be significantly reduced.

[0046] It will be noted, as illustrated non-limitingly in [Fig.3], that step 10-30 may include a preliminary substep 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 among the gradient of evolution of the position of the first valve VI (controlling the access of the boost air to the first inlet El), an operating setpoint of a turbocharger control actuator TC (which supplies the boost air), and the ratio rp between the measured pressure pasm of the boost 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 lookup table (or mapping) stored in a memory (for example of the estimation device DD) and establishing a correspondence between multiplets of difference dp values ​​and parameter(s) and filtering coefficient values.

[0049] Also, for example, in substep 20 of step 10-30, the estimated saturation pressure pse(t) at time t can be equal to the sum of the filtering coefficient cf multiplied by the measured pressure pasm of the charge air and the estimated saturation pressure pse(tl) at time t-1 preceding t multiplied by the difference between the number 1 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 on [Fig.2], that the engine computer CM (or the computer of the estimation device DD) may also include a mass memory MME, in particular to store the measured pressure pasm, the possible atmospheric pressure in progress 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, as well as any intermediate data involved in all its calculations and processing.Furthermore, this engine control unit (ECU) CM (or the estimation device ECU DD) may also include an input interface IE for receiving at least the measured pressure pasm, the current atmospheric pressure patm (if any), and the gradient of the first valve position VI (if any), and / or the operating setpoint of the turbocharger control actuator TC (if any), and / or the ratio rp (if any), 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 digital signal processor PR2. In addition, this engine control unit (ECU) CM (or the estimation device ECU DD) may also include an output interface IS, notably 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 type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the estimation process described above to estimate the air pressure pae in the intake distributor RA coupled to the internal combustion engine MT of a vehicle.

Claims

Demands

1. A method for estimating an air pressure in an intake distributor (RA) comprising i) at least one inlet (El) suitable for receiving boost 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 its upper limit 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 filter having an action on the latter which is a function of an amplitude of variations during said measured pressure.

2. Method according to claim 1, characterized in that in said step (10-30) the greater said amplitude of the ongoing variations is, the less said action of the filtering is important 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 that is at least a function of a difference between an atmospheric pressure in progress 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 further a function of at least one parameter chosen from a gradient of evolution of a position of a valve (VI) controlling an access of said boost air to said inlet (El), an operating setpoint of a control actuator of a turbocharger (TC) equipping said vehicle and supplying said boost air, and a ratio between said measured boost air pressure 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 of the saturation pressure estimated at a time t-1 preceding t multiplied by a difference between the number one and said filtering coefficient.

6. Product computer program comprising a set of instructions which, when executed by processing means, is suitable for putting implement the estimation method according to any one of claims 1 to 5, in a vehicle comprising a heat engine (MT) and an intake distributor (RA) comprising i) at least one inlet (El) suitable for receiving boost air under a measured pressure, and ii) outlets (SI) suitable for supplying distributed air to said heat engine (MT), to estimate an air pressure in said intake distributor (RA).

7. Estimating device (DD) for estimating an air pressure in an intake distributor (RA) comprising i) at least one inlet (El) suitable for receiving boost air under a measured pressure, and ii) outlets (SI) suitable for supplying distributed air to a heat engine (MT) of a vehicle, said estimating device (DD) comprising at least one processor (PR1) and at least one memory (MD) arranged to perform the operations of estimating said air pressure using as its upper limit a saturation pressure upstream of said inlet (El), characterized in that said processor (PR1) and memory (MD) are arranged to perform the operations of estimating said saturation pressure by applying to said measured pressure a filter having an action on the latter which is a function of an amplitude of variations during said measured pressure.

8. Vehicle comprising a heat engine (MT) and an intake distributor (RA) comprising i) at least one inlet (El) suitable for receiving boost air under a measured pressure, and ii) outlets (SI) suitable for 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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