WO2018154410A1

WO2018154410A1 - Pressure sensor emulating process in a vehicle and supply system for the engine of a vehicle

Info

Publication number: WO2018154410A1
Application number: PCT/IB2018/050865
Authority: WO
Inventors: Marco MORANI
Original assignee: Landi Renzo S.P.A.
Priority date: 2017-02-27
Filing date: 2018-02-13
Publication date: 2018-08-30
Also published as: EP3585992A1; IT201700022054A1

Abstract

Pressure sensor (3) emulating process in a vehicle, comprising the steps of: sending an actuation control (ca') to a high pressure pump (Php) so that such pump (Php) receives petrol (C1) at an inlet pressure (pi) and dispenses it to petrol injectors (I1) at an outlet pressure (pu) that is higher than the inlet pressure (pi); detecting a signal at the petrol injectors (I1) representing the outlet pressure (pu) of the petrol (C1); detecting the actuation control (ca) sent to the high pressure pump (Php); generating an emulation signal (pe) emulating the outlet pressure (pu) in response to a rated pressure (pt) for the petrol (C1), to the actuation control (ca) detected and to a rated actuation control (ct) of the high pressure pump (Php) pre-set during calibration; sending the emulation signal (pe) to a petrol control unit (ECU1) which, in response to such emulation signal (pe) and at the rated pressure value (pt) of the petrol (C1), generates the actuation control (ca) which is intercepted by a gas control unit (ECU2).

Description

DESCRIPTION

PRESSURE SENSOR EMULATING PROCESS IN A VEHICLE AND SUPPLY SYSTEM FOR THE ENGINE OF A VEHICLE

Technical field

The present invention relates to a pressure sensor emulating process in a vehicle and a supply system for the engine of a vehicle.

The principle underlying the operation of vehicles with alternative fuel is that of substituting the original petrol or diesel supply with alternative, less- polluting fuels (e.g. LPG or methane) conserving as far as possible the same carburation and preventing the vehicle's electronics from noticing such substitution.

For that purpose different strategies have been implemented that allow the injection of the original fuel to be reduced while at the same time dodging the checks performed by the electronic control unit appointed to drive the injectors of such fuel.

Background art

Many known strategies envisage:

- the inhibition or "cutting" of the original fuel injectors (e.g. petrol) through the interruption of the electronic control coming from the corresponding control unit (e.g. petrol ECU);

- the emulation of the original fuel injectors (e.g. petrol) in order to report to the corresponding control unit (e.g. petrol ECU) identical loads to those that there would have been with the injectors open.

The petrol (or diesel) ECU performs checks on the driving current levels of the petrol injectors to check if the opening has taken place correctly. In performing a "cutting and emulation" strategy the petrol ECU detects a similar current to the one that would be displayed in the injector coil during petrol operation.

This is obtained through a network of passive elements (e.g. resistors) and/or active elements (e.g. transistors) that are connected to the battery voltage when the alternative fuel passes, therefore they are crossed by a current adapted to simulate that of the injectors.

These currents are in the order of a few Amperes, even with peaks of over 10 Amperes for direct injection or diesel common rail systems.

Moreover, in direct injection systems, cutting the petrol injectors implies a further risk. In such systems, the petrol injectors are facing into the combustion chamber, therefore they are at very high temperatures. In the event of a "cut" the injectors are suddenly disconnected from the petrol supply suffering an increase in thermal stress.

The Applicant has already developed an alternative emulation strategy, proposed in patent application WO2014/024088, wherein such problems are partially solved.

A brief summary of this strategy is provided below, representing the starting point for the development of the present invention.

With the same injector nozzle section, the quantity of fuel injected depends on the opening time of the injector and the pressure at which it is found. As a first approximation, the relationship is linear with time and follows a square root trend with the pressure of the fuel.

The strategy proposed in WO2014/024088 envisages acting on the pressure of the original fuel (e.g. petrol) so as to emulate a pressure value that is higher than the one really present so that the corresponding petrol ECU reduces the quantity of fuel to be injected.

In other words, by reducing the real pressure of the original fuel, the quantity to be injected in the same injection time is reduced.

This takes place by interposing an emulating device between the pressure sensor and the original fuel ECU so that the ECU receives appropriately altered pressure information, specifically a pressure value that is greater than or equal to the pressure effectively detected.

In implementing this strategy, the Applicant realised that the changeover to the alternative fuel is not completely "masked" for the original fuel ECU.

In fact, the latter is sensitive to the variation in duration of the control sent to the high pressure pump actuator. By way of example, it is considered that to obtain a certain target pressure with the petrol supply the duration of such control is about 7 ms, whereas to obtain the same target pressure with the gas supply the duration of such control is about 3 ms.

This discrepancy in the duration of the high pressure pump actuation control determines the reporting of a malfunction by the petrol ECU.

In this context, the technical task underpinning the present invention is to provide a pressure sensor emulating process in a vehicle and a supply system for the engine of a vehicle, which obviate the drawbacks of the prior art cited above.

Disclosure of the invention

In particular, an object of the present invention is to propose a pressure sensor emulating process in a vehicle and a supply system for the engine of a vehicle, able to further reduce the generation of diagnostic errors with respect to known solutions.

Another object of the present invention is to propose a pressure sensor emulating process in a vehicle and a supply system for the engine of a vehicle, able to further reduce the consumption of the original fuel (i.e. the more polluting fuel) with respect to known solutions.

The technical tasks and the specified objects are obtained by a pressure sensor emulating process in a vehicle, comprising the steps of:

- sending an actuation control to a first pump (Ph_P) so that the first pump receives a first fuel at an inlet pressure and dispenses said first fuel at an outlet pressure that is higher than the inlet pressure;

- supplying the first series of injectors with the first fuel dispensed by the first pump;

- detecting a signal representing the outlet pressure of the first fuel at said first series of injectors;

- detecting the actuation control sent to the first pump;

- generating an emulation signal of the signal representing the outlet pressure in response to a rated pressure for the first fuel, to the actuation control detected and to a rated actuation control of the first pump pre-set during calibration;

- sending the emulation signal to a first control unit configured to drive the first series of injectors, in response to said emulation signal and to the rated pressure value of the first fuel, said first control unit generating the actuation control (c_a) which is intercepted by a second control unit configured to drive a second series of injectors of a second fuel (and to control said first pump.

According to an embodiment of the invention, in response to receiving the actuation control, said second control unit inhibits the actuation of the first pump so that the first fuel is dispensed by the first pump at a pressure equal to the inlet pressure.

According to an embodiment of the invention, in response to receiving the actuation control, the second control unit generates a further actuation control of the first pump.

According to an embodiment of the invention, the actuation control sent to the first pump is made available to a diagnostic unit in the form of a duty percentage.

Alternatively, the actuation control sent to the first pump corresponds to a duration of the control read via hardware.

Preferably, the emulation signal is generated by the second control unit. The technical tasks and the specified objects are obtained by a supply system for the engine of a vehicle, comprising:

- a first series of injectors for injecting a first fuel;

- a second series of injectors for injecting a second fuel;

- a first control unit configured to control the supply of the first fuel to thefirst series of injectors;

- a second control unit configured to control the supply of the second fuel to the second series of injectors;

- a tank containing a first fuel at an inlet pressure;

- a first pump interposed between the tank and the first series of injectors, the first control unit being configured to generate an actuation control to control the first pump therefore the first pump takes the first fuel from the tank at the inlet pressure and dispenses the first fuel to the first series of injectors at an outlet pressure higher than the inlet pressure;

- a pressure sensor situated in proximity to the first series of injectors for detecting a signal representing the outlet pressure of the first fuel;

- a means for detecting the actuation control of the first pump;

- an emulation device configured to generate an emulation signal of the signal representing the outlet pressure in response to a rated pressure

(p_t) for the first fuel (d), to the actuation control detected and to a rated actuation control of said first pump pre-set during calibration, said first control unit receiving the incoming emulation signal and, in response to the latter and to the rated pressure value of the first fuel, generating the actuation control intercepted by said second control unit.

Breve descrizione dei diseqni

Further characteristics and advantages of the present invention will more fully emerge from the non-limiting description of a preferred but not exclusive embodiment of a pressure sensor emulation process in a vehicle and a supply system for the engine of a vehicle, as illustrated in the accompanying drawings, in which:

- figure 1 illustrates a simplified diagram of a supply system for the engine of a vehicle, according to the present invention;

- figures 2 and 3 illustrate the block diagram of the supply system of figure 1 , in two different variant embodiments.

Detailed description of the preferred embodiments of the invention

Some useful definitions are provided below for understanding the invention. The first fuel Ci is the more polluting fuel used by the vehicle, for example petrol or diesel. In the sector, the first fuel Ci is also known as the "original fuel".

The second fuel C₂ is the less polluting fuel used by the vehicle, for example LPG or methane. In the sector, the second fuel C₂ is also known as the "alternative fuel".

The first pump P_hP is also known in the field by the term "high pressure pump".

The rated pressure p_t of the first fuel Ci is known in the field by the technical term "target pressure". The rated pressure value p_t varies according to the engine's load conditions.

The rated actuation control c_t of the first pump P_hp, also called "target control", is pre-set during calibration according to the engine's load conditions.

With reference to the figures, number 1 denotes a supply system 1 for the engine of a vehicle.

The supply system 1 comprises:

- a first series of injectors for injecting a first fuel C-i, such as, for example, petrol or diesel;

- a second series of injectors l₂ for injecting a second fuel C₂, such as, for example, LPG or methane;

The supply of each fuel is controlled by dedicated control units.

In particular, a first control unit ECUi is configured to control the supply of the first fuel Ci towards the first series of injectors \^ and a second control unit ECU₂ is configured to control the supply of the second fuel C₂ towards the second series of injectors l₂.

Assuming, for simplicity purposes, that petrol is used as the first fuel Ci and LPG as the second fuel C₂, below the first series of injectors \^ will also be indicated as "petrol injectors" and the second series of injectors l₂ also as "gas injectors". Likewise, the first control unit ECUi will also be indicated by the term "petrol ECU" and the second control unit ECU₂ with the term "gas ECU".

The first fuel Ci is contained in a tank 2 at atmospheric pressure.

Between the tank 2 and the petrol injectors a first pump P_hP is interposed (hereinafter simply known as "high pressure pump").

In the tank 2 a second pump P|_P is located (hereinafter simply known as "low pressure pump").

The first control unit ECUi is configured to generate an actuation control c_a' to control the first pump P_hp therefore the latter takes the first fuel Ci from the tank 2 at an inlet pressure p, (e.g. 5 bar) and dispenses such first fuel Ci to the first series of injectors at an outlet pressure p_u higher than the inlet pressure p,.

In particular, the outlet pressure p_u is variable according to the operating condition of the vehicle's engine. For example, values comprised between 20 bar up to over 200 bar can be obtained. The quantity of the first fuel Ci injected into the engine cylinder will be higher the higher the outlet pressure p_u.

The supply system 1 further comprises a pressure sensor 3 situated in proximity to the first series of injectors for detecting a signal representing the outlet pressure p_u of the first fuel C-i.

For example, in one embodiment, illustrated in fig. 2 (which will be described in detail below), the actuation control c_a of the first pump P_hp is made available to a diagnostic unit 4 (hereinafter also abbreviated as "OBD", which stands for On-Board Diagnostics) in the form of a cyclic opening ratio of the fuel pressure regulator c_a% (known as "duty"), in percentage format.

The supply system 1 comprises an emulation device configured to generate an emulation signal p_e of the signal representing the outlet pressure p_u in response:

- to a rated pressure p_t for the first fuel Ci , variable according to the motor load conditions;

- to the actuation control c_a detected; - to a rated actuation control c_t of the first pump P_hp pre-set during calibration.

In particular, the target pressure p_t is acquired by the gas ECU through the diagnostic unit 4.

The emulation signal p_e of the signal representing the outlet pressure p_u is hereinafter also referred to as the "emulated pressure".

In the embodiment described and illustrated herein, the second control unit ECU₂ comprises the emulation device. In other words, the emulation device is part of the second control unit ECU₂.

In an alternative embodiment (not illustrated), the emulation device is a distinct and separate device with respect to the second control unit ECU2.

The first control unit ECU₁ receives the incoming emulation signal p_e and, in response to the latter and to the rated pressure value p_t of the first fuel

Ci, generates an actuation control c_a which is intercepted by the second control unit ECU₂.

The pressure sensor emulation process in a vehicle, according to the present invention, is described below.

Such process comprises the steps of:

- sending the actuation control c_a' to the first pump Ph_P, therefore the first pump P_hp dispenses the first fuel Ci at an outlet pressure p_u that is higher than the inlet pressure p,;

- supplying the first series of injectors with the first fuel Ci dispensed by the first pump Ph_P;

- detecting the signal representing the outlet pressure p_u of the first fuel Ci at the first series of injectors ;

- detecting the actuation control c_a sent to the first pump Ph_P;

- generating the emulation signal p_e of the signal representing the outlet pressure p_u in response to the rated pressure p_t for the first fuel Ci, to the actuation control c_a detected and to the rated actuation control c_t of the first pump Ph_P pre-set during calibration;

- sending the emulation signal p_e to the first control unit ECU1. The first control unit ECUi drives the first series of injectors in response to the emulation signal p_e and to the rated pressure value p_t of the first fuel

In particular, the first control unit ECUi generates the actuation control c_a which is intersected by the second control unit ECU₂, appointed to drive the second series of injectors .

In the embodiment described and illustrated herein, the emulation signal p_e is generated by the second control unit ECU₂.

For example, in response to receiving the actuation control c_a, the second control unit ECU2 generates a further actuation control c_a' of the first pump Ph_P. Such further actuation control c_a' may be the same as the original actuation control c_a (c_a = c_a) or may be changed in terms of duration and/or phasing (i.e. possibly delayed or partially inhibited) for the purpose of regulating the real pressure at values lower than those that would be displayed during normal petrol operation.

In accordance with a preferred embodiment, the further actuation control Ca = 0. In fact, in response to receiving the actuation control c_a, the second control unit ECU2 inhibits the actuation of the first pump Ph_P so that the latter dispenses the first fuel Ci at a pressure equal to the inlet pressure p,. In other words, the first fuel Ci (e.g. petrol) is brought to the petrol injectors at low pressure (typically around 5 bar). For example, such interruption is performed by means of a relay.

To emulate the petrol pressure during gas operation, the gas ECU acquires the target pressure p_t through the diagnostic unit 4. Alternatively, the target pressure p_t is mapped during the vehicle configuration step.

The actuation control c_a of the high pressure pump Ph_P may be acquired in two alternative methods, described below.

In the first method, already mentioned above, the actuation control c_a is read by the OBD line in the form of a cyclic opening ratio of the fuel pressure regulator c_a% (known as "duty"), in percentage format.

In the second method, the actuation control c_a is read via hardware in the form of the duration of the control or an equivalent electrical magnitude. Preferably, the target control c_t is mapped during the vehicle configuration step. The format of the values of this map is the same as that used for acquiring the actuation control c_a of the high pressure pump P_hp.

During gas operation, the gas ECU can cut off the pressure sensor 3, for example, through a relay, and emulate to the petrol ECU a pressure value around the target pressure p_t, applying a corrective factor depending on the difference between the actuation control c_a of the high pressure pump P_hp detected and the target control c_t.

Referring to the first method of acquiring the actuation control c_a, the formula of the emulated pressure p_e is:

where:

- c_a% is the "duty" percentage read for the actuation control c_a of the high pressure pump Ph_P;

- Ct% is the target control percentage;

- f is a function that has a proportional component to the difference (c_t% - c_a%), possibly with integrative and/or derivative components.

If c_a% > c_t%, the emulated pressure p_e will be higher than the target pressure p_t in order to bring the control c_a closer to the target control c_t (therefore the formula will apply the "+" sign).

If c_a% < c_t%, the emulated pressure p_e will be lower than the target pressure p_t in order to bring the control c_a closer to the target control c_t (therefore the formula will apply the "-" sign).

Referring to the second method of acquiring the actuation control c_a, the formula of the emulated pressure p_e is:

where:

- T_a is the duration of the actuation control c_a of the high pressure pump P_hp;

- T_t is the duration of the target control; - f is a function that has a proportional component to the difference (T_t - T_a), possibly with integrative and/or derivative components.

If T_a > T_t, the emulated pressure p_e will be higher than the target pressure p_t in order to lower the duration of the actuation control T_a (therefore the formula will apply the "+" sign).

If T_a < T_t, the emulated pressure p_e will be lower than the target pressure p_t in order to increase the duration of the actuation control T_a (therefore the formula will apply the "-" sign).

The supply system proposed herein is further configured to perform a leak diagnosis, i.e. it is configured to verify the presence of any leaks on the fuel supply system in the switch off step, when the gas ECU cuts off the actuator of the high pressure pump Ph_P. The process for diagnosing the presence of leaks envisages emulating an appropriate pressure value for the entire duration of the diagnosis (which can be calibrated during the vehicle configuration), as the vehicle is switched off and, for vehicles with the "Start and Stop" system, during the Stop step.

As is known, a "Start and Stop" system switches off and automatically restarts an internal combustion engine so as to reduce the time for which the engine is running and the vehicle is stopped, in order to reduce fuel consumptions and reduce polluting emissions.

The characteristics of pressure sensor emulating process in a vehicle and a supply system for the engine of a vehicle, according to the present invention, prove to be clear from the description provided as do the advantages thereof. In particular, in the invention proposed herein the gas ECU is able to emulate the petrol pressure so as to prevent diagnostic errors during the following steps:

- correct pursuit of the target pressure as the engine operating conditions vary;

- correct pursuit of the actuation control of the high pressure pump, congruently with the pressure generated at the outlet of such pump;

- control of fuel leaks in the supply system as the vehicle is switched off. It is precisely the new method of handling of the high pressure pump, i.e. the possibility to read the high pressure pump actuation control (through OBD or via hardware) that allows diagnostic errors connected with the pressure regulation system performance to be prevented.

Furthermore, in the event that the actuation of the high pressure pump is inhibited, the reduction of the petrol pressure drastically reduces consumption as the injectors themselves are opened. Furthermore, real pressure limitation strategies are not necessary (with low pressures, the overpressure valve never intervenes), with a further advantage in terms of reduced consumptions and polluting emissions.

Finally, the drivability of the vehicle is improved due to the presence of only one fuel (e.g. gas) in many operating conditions.

Claims

1 . Pressure sensor (3) emulating process in a vehicle, comprising the steps of:

sending an actuation control (c_a') to a first pump (P_hp) so that said first pump (P_hp) receives a first fuel (d) at an inlet pressure (p,) and dispenses said first fuel (C-i) at an outlet pressure (p_u) that is higher than the inlet pressure (p,);

supplying the first series of injectors ( ) with the first fuel (C-i) dispensed by the first pump (P_hp);

detecting a signal representing the outlet pressure (p_u) of the first fuel (C-i) at said first series of injectors ( );

detecting the actuation control (c_a) sent to the first pump (P_hp);

generating an emulation signal (p_e) of said signal representing the outlet pressure (p_u) in response to a rated pressure (p_t) for the first fuel (Ci), to the actuation control (c_a) detected and to a rated actuation control (c_t) of said first pump (P_hp) pre-set during calibration;

sending said emulation signal (p_e) to a first control unit (ECU-i) configured to drive said first series of injectors ( ), in response to said emulation signal (p_e) and to the rated pressure value (p_t) of the first fuel (Ci), said first control unit (ECU-i) generating the actuation control (c_a) which is intercepted by a second control unit (ECU₂) configured to drive a second series of injectors ( ) of a second fuel (C₂) and to control said first pump

(Php)-

2. Process according to claim 1 , wherein, in response to receiving the actuation control (c_a,) said second control unit (ECU₂) inhibits the actuation of the first pump (P_hP) so that the first fuel (C-i) is dispensed by said first pump (P_hp) at a pressure equal to the inlet pressure (p,).

3. Process according to claim 1 , wherein, in response to receiving the actuation control (c_a,) said second control unit (ECU₂) generates a further actuation control (c_a ) of said first pump (P_hP).

4. Process according to any one of the preceding claims, wherein the actuation control (c_a) is made available to a diagnostic unit (4) in the form of a duty percentage.

5. Process according to any one of the preceding claims, wherein the actuation control (c_a) corresponds to a duration of the control read via hardware.

6. Process according to any one of the preceding claims, wherein the emulation signal (p_e) is generated by said second control unit (ECl ).

7. Supply system (1 ) for the engine of a vehicle, comprising:

a first series of injectors ( ) for injecting a first fuel (C-i);

a second series of injectors (I₂) for injecting a second fuel (C₂);

a first control unit (ECU₁) configured to control the supply of the first fuel (C-i) to said first series of injectors ( );

a second control unit (ECU₂) configured to control the supply of the second fuel (C2) to said second series of injectors (I2);

a tank (2) containing a first fuel (C-i) at an inlet pressure (p,);

a first pump (P_hp) interposed between the tank (2) and the first series of injectors ( ), said first control unit (ECU-i) being configured to generate an actuation control (c_a) to control the first pump (P_hP) therefore said first pump (P_hp) takes the first fuel (C-i) from the tank (2) at the inlet pressure (pi) and dispenses said first fuel (d) to the first series of injectors ( ) at an outlet pressure (p_u) higher than the inlet pressure (p,);

a pressure sensor (3) situated in proximity to the first series of injectors ( ) for detecting a signal representing the outlet pressure (p_u) of the first fuel a means for detecting (4) said actuation control (c_a) of the first pump (P_hP); an emulation device configured to generate an emulation signal (p_e) of said signal representing the outlet pressure (p_u) in response to a rated pressure (p_t) for the first fuel (C-i), to the actuation control (c_a) detected and to a rated actuation control (c_t) of said first pump (P_hP) pre-set during calibration, said first control unit (ECU₁) receiving the incoming emulation signal (p_e) and, in response to the latter and to the rated pressure value (p_t) of the first fuel (C-i), generating the actuation control (c_a) intercepted by said second control unit (ECU2).

8. Supply system (1 ) according to claim 7, wherein said second control unit (ECU₂) comprises said emulation device.

9. Supply system (1 ) according to claim 7 or 8, wherein said detecting means (4) consists of a diagnostic unit (4).