FR3138475A1 - SYSTEM AND METHOD FOR DETECTING CLOGGING OF A PARTIAL LOAD CHECK VALVE OF A THERMAL ENGINE, VEHICLE COMPRISING SUCH A SYSTEM - Google Patents

Abstract

The invention relates to a system for detecting clogging of an upstream non-return valve (V1) of a motor vehicle thermal engine. The heat engine comprises: - a pressure regulating valve (RV) in an oil separator (D) of a cylinder head (C2); - an upstream non-return valve (V1) arranged in the oil separator (D), at the level of a internal return (R) towards an intake tube (TA), - a downstream non-return valve (V2) connected to a secondary gas ventilation line (LG) coming from the cylinder head (C2). According to the invention, the detection system comprises: - a first and a second absolute pressure sensors (AP1, AP2) respectively for the upstream of the crankcase (C1) and the cylinder head (C2). The blockage diagnosis is made on the basis of sensor pressures (AP1, AP2), and a pressure loss. The invention also relates to a method and vehicle based on such a system. Figure 1

Description

SYSTEM AND METHOD FOR DETECTING CLOGGING OF A PARTIAL LOAD CHECK VALVE OF A THERMAL ENGINE, VEHICLE COMPRISING SUCH A SYSTEM

The present invention relates to a system and a method for detecting clogging of a non-return valve of a crankcase of a heat engine, in particular in addition to leak detection of a valve for regulating the pressure of the crankcase of the engine. thermal motor. The invention further relates to a vehicle comprising such a system.

Heat engines have combustion gas passages between the pistons and the cylinders to arrive in the engine crankcase connected to the interior volume of the cylinder head and to an oil separator.

The invention proposes a complementary solution to the co-pending application FR2109281 which concerns a method for detecting a leak from a pressure regulating valve of a motor vehicle thermal engine casing.

In certain dysfunctional life cases, the so-called partial load upstream check valve in the cylinder head, or the so-called high load downstream check valve downstream of the crankcase, can be clogged. In the first case, the leak detection strategy is ineffective, the partial load valve being clogged.

Thus, an objective of the invention is to remedy the defects of the prior art, and in particular to propose a system and a method for detecting clogging of the so-called partial load upstream non-return valve.

To achieve this objective, the invention proposes a system for detecting clogging of an upstream non-return valve intended for a motor vehicle thermal engine casing,
the heat engine comprising:
- a gas intake box,
- a cylinder head comprising an oil separator, connected downstream of the gas intake housing, equipped with an intake tube connected to the intake housing and an outlet tube, and mounted on the crankcase,
- a pressure regulating valve placed in the oil separator;
- the upstream non-return valve located in the oil separator at the level of an internal return to the intake tube,
- a downstream non-return valve connected to a secondary gas ventilation line from the oil separator,
characterized in that the detection system comprises:
- a first absolute pressure sensor for measuring a pressure downstream of the gas intake housing;
- a second absolute pressure sensor to measure pressure in the oil separator; And
- a diagnostic means for diagnosing a blockage of the upstream non-return valve if the pressure determined by means of the second absolute pressure sensor is greater than the pressure determined by means of the first absolute pressure sensor to which is added a pressure loss of a partial load return in the cylinder head and a determined threshold.

In particular, the regulation valve is a membrane valve; the upstream non-return valve is placed at the inlet of the return of the leak gases (or “blow-by gas” in English) when the engine is operating at partial load, so as to return the deoiled gases to the combustion chamber; and the second absolute pressure sensor is arranged downstream of the pressure regulation, before the downstream non-return valve.

Advantageously, the invention involves a strategy which makes it possible to detect dysfunctional life cases at the level of the upstream non-return valve (also called the so-called partial load valve in the state of the art, or first non-return valve in the detailed description which follows ). This strategy is based on the presence of an absolute pressure sensor located inside the oil separator.

According to a variant, the detection system further comprises confirmation means for confirming a diagnosis of blocking of the non-return valve if the pressure determined by means of the second absolute pressure sensor remains greater than the pressure determined by means of the first absolute pressure sensor to which is added the flow rate and the determined threshold, for a confirmation time.

This allows for confirmation of diagnosis while avoiding false positives.

According to a variant, the detection system further comprises means for evaluating an upstream pressure corresponding to the pressure upstream of the gas intake housing; means for measuring an oil temperature in the crankcase; as well as an activation means to activate a diagnosis if:
- the upstream pressure is greater than the pressure determined by means of the first absolute pressure sensor;
- an oil temperature is lower than an estimated temperature range for evaporation of the ethanol contained in the oil.

In particular, the oil temperature must be outside the ethanol evaporation ranges. The ethanol evaporation range is defined by temperatures Tmin and Tmax (for example between Tmin = 70°C and Tmax = 90°C) which fall into the exclusion zone of the first two diagnostics of clogging of the ethanol. flaps (excluding security strategy, which has no activation conditions).

This variant makes the presence of the diagnosis dependent or not on the temperature of the oil, allows, in the case where one wishes to make this diagnosis on engines using fuels with a high level of ethanol, to avoid making false detections during the evaporation phases of the ethanol contained in the oil in the tank, following fuel dilution in the oil tank. Indeed, for these specific fuels, the leak gas flow rates increase suddenly during the evaporation phases which are centered around the evaporation temperatures of the ethanol, which causes the crankcase to increase in pressure. Maintaining the diagnosis in this evaporation phase runs the risk of false detection of a clogged valve.

This allows the diagnosis to be limited to specific temperature and pressure conditions for which the diagnosis is relevant.

According to a variant, the means for evaluating an upstream pressure calculates the upstream pressure on the basis of an atmospheric pressure measurement and a model.

According to a variant, the detection system further comprises an alert means for signaling a clogging of the upstream non-return valve based on a diagnosis of the diagnostic means and/or a confirmation of the confirmation means.

This makes it possible to alert the user and the maintenance service of the corresponding motor vehicle of the clogging problems involved.

Another object of the invention relates to a thermal engine system of a motor vehicle comprising a system for detecting clogging of a downstream non-return valve according to the invention.

The invention also relates to a motor vehicle comprising a thermal engine which comprises a downstream non-return valve, and a system for detecting clogging of the downstream non-return valve according to the invention.

The invention further relates to a method for detecting clogging of an upstream check valve by means of a system for detecting clogging of the upstream check valve according to the invention, the method comprising the following steps:
- measure a pressure downstream of the gas intake housing by means of the first absolute pressure sensor;
- measure pressure in the oil separator using a second absolute pressure sensor; And
- diagnose a blockage of the upstream non-return valve if the pressure determined by means of the second absolute pressure sensor is greater than the pressure determined by means of the first absolute pressure sensor to which is added a pressure loss of a partial load return in the cylinder head and a determined threshold.

The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which:
- schematically illustrates a heat engine casing for implementing the system according to a preferred embodiment of the invention;
- schematically illustrates a detail of a method for detecting clogging of a first non-return valve according to a preferred embodiment of the invention;
- schematically illustrates a detail of a method for detecting clogging of a second non-return valve according to a preferred embodiment of the invention; And
- schematically illustrates a detail of the method for detecting a critical alert linked to the clogging of the second non-return valve.

There presents a heat engine comprising a C1 casing equipped with a C2 cylinder head. The C2 cylinder head is fixed on top of the C1 crankcase and covers the cylinders to close the combustion chambers (not shown).

An intake tube TA receives air from a cooler R via an AG gas intake box. The cooler R is connected to a turbocharger TC, itself connected to an outlet tube TS in the cylinder head C2.

The motor shown further includes a VP vacuum pump.

An FA air filter is connected to an inlet of the TC turbocharger.

The casing C1 comprises a first bypass connecting the intake tube TA to the cylinder head C2 with, at the inlet of cylinder head C2, a first non-return valve V1, which can be called a partial load valve.

The crankcase C1 also includes a pressure regulating valve RV opening into the cylinder head C2.

The outlet of the cylinder head C2 is equipped with a secondary gas ventilation line LG, terminated by a second non-return valve V2, which can be called a high load valve, connected to a heating device H, and opening between the turbocharger TC and the FA air filter.

The heat engine is also equipped with a fresh air line LA opening on the one hand between the air filter FA and the second non-return valve V2; and on the other hand in an accessory chamber of the oil separator D communicating with the rest of the cylinder head C2, at the level of a corresponding valve V3.

The invention uses the first check valve V1, a plenum sensor or first absolute pressure sensor AP1, and a second absolute pressure sensor AP2.

The first absolute pressure sensor AP1 is arranged so as to measure a pressure downstream of the gas intake housing AG; the first check valve V1 is arranged at the inlet of the cylinder head C2, downstream of the bypass of the intake tube TA; and the a second absolute pressure sensor AP2 is arranged so as to measure a pressure in the oil separator D mounted on the cylinder head C2, downstream of the crankcase gas pressure regulation membrane, and upstream of the partial load V1 and full load valves V2.

In the following paragraph, we do not consider the influence of the fresh air line LA (air dilution). Indeed, this branch has a minor impact on the proposed strategy. The different life cases identified are then as follows:

Situation YOUR V1 V2 Det. Stat1 V1_0 V2_0 Stat2 1 F F F 0_D OK 0_D 0_D OK 2 F BO F 0_D OK 0_D 0_D OK 3 F B.F. F 0_D OK CB_F 0_D OK 4 F F BO D.F. F_D 0_D 0_D F_D 5 F F BO 0_D N1 0_D CB_F OK 6 F BO BO D.F. F_D D.F. 0_D F_D 7 F B.F. B.F. 0_D OK CB_F CB_F OK 8 F BO B.F. 0_D OK 0_D CB_F OK 9 F B.F. BO 0_D OK CB_F 0_D OK 10 O F F D.F. OK 0_D 0_D OK 11 O BO F D.F. OK 0_D 0_D OK 12 O B.F. F 0_D NOK CB_F 0_D OK 13 O F BO D.F. OK 0_D 0_D OK 14 O F BO D.F. OK 0_D 0_D OK 15 O BO BO D.F. OK 0_D 0_D OK 16 O B.F. B.F. 0_D NOK CB_F 0_D OK 17 O BO B.F. D.F. OK 0_D 0_D OK 18 O B.F. BO 0_D NOK CB_F 0_D OK

In table 1, the first column concerns different situations depending on the states of the secondary line LG, the first and second check valves V1, V2, “Det. »: the implementation or not of a leak detection strategy for example according to the co-pending request FR2109281; “Stat1”: the status of the system with respect to the regulatory requirements for sensorless systems; “V1_R”, “V2_R”: the effective detection of the first and second blocked check valves; and “Stat2”: the status of the system with respect to the regulatory requirements for a sensorless system.

“F” means functional, for example a working LG line, and “O” means an open LG line. “BO means “a valve stuck open”, “BF” means “blocked closed”. “O_D” means “no detection”, and “DF” means “leak detection”. “OK” means status compliant with regulatory requirements, and “NOK” means “non-compliant”. “N1” means “OK with regard to the sealing of the LG line but increased pressure from the second non-return valve V2, and risk of leakage”. “CB_F” means “detection of valve stuck closed”, and “F_D” means “false leak detection but regulatory”.

Situations 12, 16 and 18 lead to the absence of leak detection relating to the regulatory requirement for detection of an LG line system (or “blow-by” tube, or leaky regulation membrane). These three cases correspond to a V1 valve (at partial load), stuck closed. The proposed strategy is to compare the pressure measured at the oil separator (AP1) to the pressure in the cylinder head (AP2) (downstream of the AG gas intake box – or throttle box in English). The AP2 sensor used is an absolute pressure sensor which has the same characteristics as the AP1 plenum pressure sensor.

Concerning the diagnosis at the level of the first check valve V1 (illustrated in ), the detection strategy can be limited to a detection range according to a minimum N regime denoted Nmin and a maximum N regime denoted Nmax coupled with a minimum C load denoted Cmin and a maximum C load denoted Cmax.

In addition, the detection strategy can be limited to a detection range based on a minimum and a maximum plenum pressure P _AP1 .

In addition, the strategy can use an oil temperature signal relative to the oil measured at the crankcase ramp C1. A temperature sensor can be provided for this purpose in the crankcase oil rail. Thus, the detection strategy can be limited to an oil temperature range T _oil located outside the estimated evaporation range of the ethanol contained in the oil. We can talk about evaporation temperature, but this depends on the physicochemical conditions, the temperature and the pressure, as well as the purity of the ethanol. Variations in evaporation temperatures define such an evaporation zone.

The pressure sensor signals are preferably filtered (F1 filters).

Preferably, an application condition is implemented on the basis of an upstream pressure P1 and the plenum pressure P _AP1 . If the upstream pressure P1 is greater than the plenum pressure P _AP1 , also with the aforementioned limitations, then the diagnosis of the first check valve V1 is carried out.

The upstream pressure P1 can be calculated based on an atmospheric pressure measurement P0 and a model.

Concerning the diagnosis of the first check valve V1 (illustrated in ), it is evaluated on the basis of the pressure values P _AP1 , P _AP2 . The signals from the pressure sensors AP1, AP2 are preferably filtered by means of a filter F1.

The diagnosis also depends on a calculation of the pressure loss DP of the partial load return in the cylinder head from a matrix of speeds N and loads C. The speeds are for example (in rpm): 750, 1000, 2000, 3000, 4000, and 5000. The loads are for example (in N.m): 0, 10, 20, 30, 40, 80, 100.

If the diagnosis is activated, and if the pressure P _AP2 is greater than the pressure P _AP1 to which is added the pressure loss DP and a determined threshold S1, then this may mean that the valve V1 is stuck closed. Preferably, if this is maintained for a time greater than a confirmation time T _conf , for example 2s, then the diagnosis is confirmed. In this case, the valve V1 is judged to be blocked and it is preferably in this case that an alert is communicated to the user.

In the preferred variant, the strategy is therefore active in the atmospheric operating range of the engine, as well as in more restricted areas relating to the speed, torque, as well as the plenum pressure P _AP1 measured. It is also possible not to carry out the diagnosis during the evaporation phases of the ethanol contained in the oil, which can lead to significant increases in gas ventilation flow (“blow-by” in English), then leading to significant pressure losses in the system, and therefore a possible risk of false detection. Incoming signals (sensor measurements) are filtered in order to limit transient phenomena which could lead to false detection. The activation and removal of the fault is then conditioned by a confirmation time. The values are given for information purposes only.

Concerning the detection at the level of the second non-return valve V2 (illustrated in ), the presence of the pressure sensor AP2 also ensures the possible detection of the second blocked non-return valve V2. The principle of the strategy is similar. We place ourselves in the supercharged operating range to make this diagnosis and detect a rise in pressure in the oil separator.

The pressure sensor signals are filtered.

The detection strategy can be limited to a detection range based on a minimum and a maximum plenum pressure P _AP1 .

In addition, the detection strategy can be limited to an oil temperature range T _oil located outside the evaporation temperature range of the ethanol contained in the oil tank (dilution of fuel in the oil).

An activation condition can be determined on the basis of the upstream pressure P1 having a value lower than that of the plenum pressure P _AP1 with in addition the aforementioned limitations. In this case, the diagnosis of valve V2 is then carried out.

The diagnosis is carried out on the basis of the value of the pressure P _AP2 from which the value of the measured atmospheric pressure P0 is subtracted, to evaluate an overpressure. This overpressure must be greater than an overpressure threshold S2, for example 50mbar, for a time greater than Tmax, for example 10s; or for a time less than Tmax, but greater than Tmin, for example 2s. In the first case, the diagnosis is that the V2 valve is judged to be critically stuck (preferably with a corresponding alert). In the second case, the diagnosis is that the V2 valve is judged to be stuck in a non-critical manner (preferably without warning).

In the same way, this strategy preferably excludes evaporation phases. The value of the overpressure threshold S2 is given for information only. Preferably, no functional zone should be overpressured beyond this value. We propose here two diagnostics depending on the confirmation time of the sticking phenomenon of the V2 valve.

In order to respond to the security risk, we propose a third strategy which is permanently active, without restriction on the engine operating range or linked to temperature. More precisely, this strategy (illustrated in ) is permanently active when the engine is running. The associated S3 threshold as well as the confirmation duration are consistent with the security risk. Here the value is for information only.

In this strategy, said overpressure is compared to a critical overpressure threshold S3, for example 250 mbar, in a time greater than a critical time Tcrit, 1s for example.

If said overpressure is greater than the critical overpressure threshold S3 for a time greater than the critical time Tcrit, in this case there is a diagnosis of a critical overpressure fault (Dcrit.), and preferably a corresponding alert.

The alerts may include a display of one or more indicator lights, preferably specific to each of the above alerts.

Claims (6)

System for detecting clogging of an upstream non-return valve (V1) intended for a casing (C1) of a motor vehicle thermal engine,
the heat engine comprising:
- a gas intake box (AG),
- a cylinder head (C2) comprising an oil separator (D), connected downstream of the gas intake housing (AG), equipped with an intake tube (TA) connected to the intake housing (AG) and a tube output (AG), and mounted on the casing (C1),
- a pressure regulating valve (RV) placed in the oil separator (D);
- the upstream non-return valve (V1) located in the oil separator (D) at the level of an internal return (R) towards the intake tube (TA),
- a downstream non-return valve (V2) connected to a secondary gas ventilation line (LG) from the oil separator (D),
characterized in that the detection system comprises:
- a first absolute pressure sensor (AP1) for measuring a pressure downstream of the gas intake housing (AG);
- a second absolute pressure sensor (AP2) to measure pressure in the oil separator (D); And
- diagnostic means for diagnosing a blockage of the upstream non-return valve (V1) if the pressure determined by means of the second absolute pressure sensor (AP2) is greater than the pressure determined by means of the first absolute pressure sensor (AP1) at which is added a pressure loss (DP) of a partial load return in the cylinder head (C2) and a determined threshold (S1). Detection system according to claim 1, further comprising confirmation means for confirming a diagnosis of blocking of the check valve (V1) if the pressure determined by means of the second absolute pressure sensor (AP2) remains greater than the pressure determined by means of the first absolute pressure sensor (AP1) to which is added the flow rate (DP) and the determined threshold (S1), during a confirmation time (T _conf ). Detection system according to any one of claims 1 to 2, further comprising means for evaluating an upstream pressure (P1) corresponding to the pressure upstream of the gas admission box (AG); means for measuring an oil temperature (T _oil ) in the crankcase (C1); as well as an activation means to activate a diagnosis if:
- the upstream pressure (P1) is greater than the pressure determined by means of the first absolute pressure sensor (AP1);
- an oil temperature (T _oil ) is lower than an estimated evaporation temperature of the ethanol contained in the oil. Detection system according to claim 3, characterized in that the means for evaluating an upstream pressure (P1) calculates the upstream pressure (P1) on the basis of an atmospheric pressure measurement (P0) and a model . Detection system according to any one of claims 1 to 4, further comprising alert means for signaling a clogging of the upstream non-return valve (V1) as a function of a diagnosis of the diagnostic means and/or a confirmation of the means of confirmation. Method for detecting clogging of an upstream non-return valve (V1) by means of a system for detecting clogging of the upstream non-return valve (V1) according to any one of claims 1 to 5, the method comprising the following steps:
- measure a pressure downstream of the gas intake housing (AG) by means of the first absolute pressure sensor (AP1);
- measure a pressure in the oil separator (D) using a second absolute pressure sensor (AP2); And
- diagnose a blockage of the upstream non-return valve (V1) if the pressure determined using the second absolute pressure sensor (AP2) is greater than the pressure determined using the first absolute pressure sensor (AP1) to which is added a loss load (DP) of a partial load return in the cylinder head (C2) and a determined threshold (S1).