Patent Grant
10526993
This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2016/001737, filed Oct. 20, 2016, which claims priority to French Patent Application No. 1560341, filed Oct. 29, 2015, the contents of such applications being incorporated by reference herein.
The invention relates to a method for checking the operation of a high-pressure fuel supply system for an internal combustion engine comprising a booster pump, a high-pressure fuel injection pump fed by the booster pump, a regulator for the high-pressure fuel injection pump, means for activating the high-pressure fuel injection pump by means of a timing command or by means of an angle-setting command via the regulator for the high-pressure fuel injection pump and an engine control unit, a high-pressure fuel tank or common rail fed by said high-pressure fuel injection pump, means for measuring the pressure in the common rail, injectors fed with fuel by said common rail and controlled by the engine control unit to inject fuel into the cylinders of the internal combustion engine, said high-pressure fuel injection pump being capable of being driven by an electric drive means with the internal combustion engine.
In such a high-pressure fuel supply system, the fuel is transferred from the low-pressure fuel tank to the high-pressure fuel injection pump by means of the booster pump which operates at low pressure. The pressure of the fuel in the common rail is regulated by means of a PID (proportional, integral, derivative) controller, referred to as the high-pressure fuel injection pump regulator. This controller acts in combination with an actuator fitted to the high-pressure fuel injection pump, which makes it possible to transfer only as much fuel into the common rail as is necessary according to the amount of fuel required by the engine control unit for injection. To achieve this, this actuator includes a valve referred to as a DIV (digital interface valve), which makes it possible to transfer the desired amount of fuel into the common rail, and to return the fuel displaced by the high-pressure fuel injection pump but not desired in the common rail to a return circuit for returning the fuel to the low-pressure tank. The high-pressure fuel injection pump is for example a rotary piston pump that is continuously driven in rotation by the combustion engine. The actuator including a DIV will be referred to hereinafter as the DIV actuator.
The high-pressure fuel injection pump is subject to phasing between the one or more pistons thereof and the pistons of the combustion engine driving it, for example between a top dead center position of a piston of the engine and a top dead center position of a piston of the high-pressure fuel injection pump, so as to make it possible to regulate the exact amount of fuel transferred into the common rail with respect to the position of the crankshaft. The actuator including the DIV is activated by means of an electrical angle-setting command, referred to hereinafter by extension as an angle-setting command for the high-pressure fuel injection pump, produced with respect to a reference angle, i.e. a command issued at a precise angle on an axis of rotation of the high-pressure fuel injection pump, corresponding by construction to a position of the one or more pistons of said pump, so that the valve is closed at a precise position of the one or more pistons of this high-pressure fuel injection pump corresponding to a determined volume of fuel that it is desired to transfer into the common rail. The reference angle is generally set at the top dead center point of the high-pressure fuel injection pump and defined by calibration. The high-pressure fuel injection pump is phased by means of an initial calibration of the reference angle and then by learning this reference angle to account for the assembly and sensor tolerances, in particular in the present case of the high-pressure fuel injection pump and its mechanism of being driven by the combustion engine. If the phasing of the high-pressure fuel injection pump is incorrect, the amount of fuel transferred into the common rail is also incorrect, and consequently so is the pressure established in this rail.
The phasing of the high-pressure fuel injection pump is therefore subject to learning based, in a known manner, on the detection of the integral portion of the PID controller or regulator, in a certain angular window, by varying the theoretical position of the top dead center (TDC) of the high-pressure fuel injection pump. This operation of learning the phasing is performed by the engine control unit.
The electrical-control of the DIV actuator is therefore calibrated so that the electric pulse is positioned at the time of desired closure of the DIV with respect to the position of the one or more pistons of the high-pressure fuel injection pump, so that the amount of fuel determined by the engine control unit is transferred to the common rail. This electrical command of course requires knowledge of the reference angle which is set as explained above. The sequencing of the electrical command is defined during development.
Such an angle-setting command of course requires the synchronization of the engine.
Furthermore, the actuator including the DIV may be activated by means of an electrical timing command, referred to hereinafter by extension as a timing command for the high-pressure fuel injection pump, when the engine has not yet been synchronized, to make it possible to transfer fuel into the common rail before said synchronization, and hence to increase the pressure in this common rail, in particular to accelerate the engine start-up time. This timing signal generally takes the form of a squarewave PWM (pulse width modulation) electrical signal.
The high-pressure fuel injection pump is capable of being driven by an electric drive means with the internal combustion engine, for example the electric starter of the combustion engine.
The above, and in particular the learning, constitutes the elements for checking the operation of a high-pressure fuel supply system, which are known to those skilled in the art.
The maximum amount of fuel that the high-pressure fuel injection pump is able to compress depends on the angle-setting command such as explained above, determined by the regulator for said pump, and applied electrically by the engine control unit.
The performance levels of the regulator for the high-pressure fuel injection pump, of the electrical command for the actuator including the DIV, of the DIV and of said pump themselves are thus linked for the purpose of obtaining the desired result of transferring a precise amount of fuel from the high-pressure fuel injection pump to the common rail.
It is desired that the assembly of the regulator for the high-pressure fuel injection pump and of the electrical command for the actuator including the DIV is able, at any time, to load the high-pressure fuel injection pump to the maximum according to the needs of the engine control unit. There is therefore a need to ensure and to check that this maximum loading is operational. However, the following causes may distort such a check or make it difficult or even impossible:
An aspect of the present invention provides a method making it possible to check the operation of a high-pressure fuel supply system for an internal combustion engine such as defined above, and in particular making it possible to:
More specifically, an aspect of the present invention relates to a method for checking the operation of a high-pressure fuel supply system for an internal combustion engine comprising a booster pump, a high-pressure fuel injection pump fed by the booster pump, a regulator for the high-pressure fuel injection pump, means for activating the high-pressure fuel injection pump by means of a timing command or by means of an angle-setting command via the regulator for the high-pressure fuel injection pump and an engine control unit, a high-pressure fuel tank or common rail fed by said high-pressure fuel injection pump, means for measuring the pressure in the common rail, injectors fed with fuel by said common rail and controlled by the engine control unit to inject fuel into the cylinders of the internal combustion engine, said high-pressure fuel injection pump being capable of being driven by an electric drive means with the internal combustion engine, characterized in that the method consists in driving the high-pressure fuel injection pump by means of said electric drive means and, after the engine is synchronized and the injection of fuel into the cylinders is shut off, in defining an initial base pressure in the common rail, in successively activating the high-pressure fuel injection pump by means of said timing and angle-setting commands, respectively, on the basis of said initial base pressure, and in comparing the first pressure and the second pressure obtained in the common rail by means of said timing and angle-setting commands, respectively, with one another and/or at least one of said pressures with a reference pressure, to check the operation of the high-pressure fuel supply system for the internal combustion engine.
By comparing the amount of fuel compressed by the high-pressure fuel injection pump when the DIV actuator is controlled on the basis of angle with the amount of fuel compressed when the DIV actuator is controlled on the basis of time, it is possible to dissociate the performance of the high-pressure fuel injection pump and DIV actuator system on the one hand, from the electrical control and regulator system on the other. Specifically, the timing command is delinked from the electrical control and regulator system and provides targeted information on the high-pressure fuel injection pump and DIV actuator system, and the angle-setting command necessarily involves the electrical control and regulator system. The differences in fuel pressure measured in the common rail provide, by equivalence, the corresponding amounts of fuel injected into this rail.
This makes it possible to detect the following situations:
The comparison is made by measuring the difference in pressure in the common rail after one or more actions of the one or more pistons of the high-pressure fuel injection pump for each type of angle-setting and timing command.
The high-pressure fuel injection pump for implementing the method according to the invention is capable of being driven by an electric drive means with the internal combustion engine, for example the electric starter of the combustion engine.
It should be noted that according to an aspect of the invention, and unlike in the prior art, the timing command is used with the engine synchronized while its function is to actuate the high-pressure fuel injection pump when the motor is not synchronized.
According to one advantageous feature, the method according to the invention comprises the following steps:
According to another advantageous feature, said first and second determined numbers of engine revolutions are identical.
According to another advantageous feature, said initial base pressure in said common rail is substantially equal to the pressure of the booster pump.
According to another advantageous feature, said reference pressure is substantially equal to the maximum pressure delivered by the high-pressure fuel injection pump.
According to another advantageous feature, the step consisting in comparing the first and second fuel pressures with one another and/or at least one of said pressures with a reference pressure, and in using the results of the comparison to check the operation of the high-pressure fuel supply system for the internal combustion engine, comprises the following steps:
The first pressure is chosen since the timing command is the more robust command, that is to say it is certain that the DIV has been closed at the bottom dead center of the high-pressure fuel injection pump, even in the event of an alignment error in this high-pressure fuel injection pump during reassembly thereof. The first pressure does not depend on a potentially poorly aligned angle-setting command or one in which the phasing is incorrect.
The term “hydraulic system” is understood here to mean the high-pressure fuel supply system for an internal combustion engine such as defined above, without considering the electrical elements or parts, in particular the high-pressure fuel injection pump regulator and the engine control unit, or, if applicable, the system for driving the high-pressure fuel injection pump by means of the combustion engine.
According to another advantageous feature, if the first pressure is not lower than the reference pressure, the method further includes a step consisting in comparing the first and second pressures with one another, as follows:
The expression “first and second pressures being equal or substantially equal” is understood to mean a margin of error or range around parity which depends on the nature of the diesel or gasoline fuel under consideration.
According to another advantageous feature, if the first and second pressures are not equal or substantially equal, the method further includes the following steps:
According to another advantageous feature, after the step consisting in having observed that the first pressure is lower than the reference pressure, and having deemed the supply system to be non-operational, the method further comprises the following steps:
The expression “first and second pressures being equal or substantially equal” is understood to mean a margin of error or range around parity which depends on the nature of the diesel or gasoline fuel under consideration as well as the speed of the electric starter.
Other features and advantages will become apparent on reading the following examples of embodiments of a method according to the invention accompanied by the appended drawings, which examples are provided by way of nonlimiting illustration.
The high-pressure fuel supply system 1 for an internal combustion engine shown in
The hydraulic system of the fuel supply system comprises the above elements with the exception of the electrical elements or parts, in particular the regulator 5 for the high-pressure fuel injection pump 4 and the engine control unit 6. The high-pressure circuit is defined as the high-pressure fuel circuit from the high-pressure fuel injection pump 4 and downstream thereof to the injectors 9.
The high-pressure fuel injection pump 4 is capable of being driven, in a known manner, by an electric drive means (not shown) with the internal combustion engine 12, for example an electric starter or an electric machine, by virtue of a system for driving the high-pressure fuel injection pump in rotation by means of the combustion engine (not shown), for example a mechanical transmission linkage mechanism, such as a chain, gears, a belt or similar.
The method according to an aspect of the invention consists, for example, in a high-pressure fuel supply system 1 of this type, in driving the high-pressure fuel injection pump 4 by means of the electric drive means (not shown) and, after the engine 12 is synchronized and fuel injection into the cylinders 11 is shut off, in defining an initial base pressure P0 in the common rail 7, in successively activating the high-pressure fuel injection pump 4 by means of the timing and angle-setting commands, respectively, on the basis of the initial base pressure P0, and in comparing first P1 and second P2 pressures obtained in the common rail 7 by means of the timing and angle-setting commands, respectively, with one another and/or at least one of said pressures with a reference pressure Pref, to check the operation of the high-pressure fuel supply system for the internal combustion engine.
A timing command for the high-pressure fuel injection pump 4 depends on the technology of the DIV actuator, which depends on the fuel used. For example, in a known manner, a plurality of electric pulses in the form of a PWM signal is generally used for a diesel fuel, while a mean electric current is generally used for a gasoline fuel. The timing command is applied to the DIV actuator for a determined number of engine revolutions, preferably defined by a determined number of segments, one segment being equal to 720°, namely two revolutions of the engine or of the crankshaft for a four-stroke engine cycle, divided by the number of cylinders of the engine. For an internal combustion engine including four cylinders as shown in
An angle-setting command for the high-pressure fuel injection pump 4 is produced in a known manner by means of a plurality of electric pulses, for example of peak-and-hold or peak-hold type, for a determined number of segments such as defined above. As explained above, this angle-setting command is subject to a phasing with the high-pressure fuel injection pump 4.
A first example of an embodiment of a method according to an aspect of the invention will now be described with the aid of
The method for checking the operation of a high-pressure fuel supply system for an internal combustion engine according to
The reference pressure Pref is preferably chosen to have a value close to the maximum pressure delivered by the high-pressure fuel injection pump 4, for a nominal operational new system, in good working condition, for example substantially equal to this maximum pressure delivered by the high-pressure fuel injection pump 4.
The numbers of segments N1, N2 are chosen such that the response of the high-pressure fuel injection pump 4 through the pressures P1, P2 reached in the common rail 7 on completion of these segments N1, N2 is as close as possible to the maximum pressure that can be obtained with the high-pressure fuel injection pump 4, hence with an angle-setting command or with a timing command. Preferably, to allow a direct comparison, the first N1 and second N2 determined numbers of segments are identical.
The initial base pressure P0 in the common rail 7 is substantially equal to the pressure of the booster pump 2, namely the lowest possible pressure, so as to increase the difference in pressure ultimately measured in the common rail 7 for the pressures P1 and P2 with respect to P0.
As shown in
Advantageously, if the first pressure P1 is not lower than the reference pressure Pref, the method further includes a step 1012 consisting in comparing the first P1 and second P2 pressures with one another, as follows:
Preferably, if the first P1 and second P2 pressures are not equal or substantially equal, the method further includes the following steps:
With this step 10122, the purpose is to eliminate two of the potential causes of the fault in the supply system, namely a phasing fault or a fault in learning the phasing.
In step 1012212, P1 is equal or substantially equal to P2, which are both equal or substantially equal to Pref, meaning that the system 1 is perfectly operational, the new learning operation having solved the problem raised in step 1012 resulting from the observation that P1 is not equal or substantially equal to P2.
Preferably, after step 1011 consisting in having observed that the first pressure P1 is lower than the reference pressure Pref, and having deemed the supply system to be non-operational, the method further comprises the following steps:
In step 101111, the first P1 and second P2 pressures are equal or substantially equal, meaning that the regulator 5 is operational, the timing and angle-setting commands being operational. Thus, the regulator 5 is not the cause. However, it is recalled that these pressures P1 and P2 are lower than the reference pressure Pref as observed in prior steps 101 and 1011, which means that there is a possible unspecified fault among the three possibilities mentioned above, namely:
In step 101112, the first P1 and second P2 pressures are not equal or substantially equal, meaning that the regulator 5 is not operational, the timing and angle-setting commands not performing identically.
This diagnosis is added to the three possible faults detected in step 101111 above.
Key for
Step 10: Drive high-pressure fuel injection pump
Step 20: Engine synchronization
Step 30: Injector deactivation
Step 40: Common rail initial base pressure P0
Step 50: High-pressure fuel injection pump timing command for N1 engine revolutions
Step 60: Common rail pressure P1 measurement
Step 70: Re-establish initial base pressure P0 in common rail
Step 80: High-pressure fuel injection pump angle-setting command for N2 engine revolutions
Step 90: Common rail pressure P2 measurement
Step 100: P1, P2, Pref comparison—verify operation of high-pressure fuel supply system
Step 101: P1<Pref
Step 1011: Supply system non-operational
Step 10111: P1=P2
Step 101111: High-pressure circuit leak, or high-pressure fuel injection pump ineffective or booster pump ineffective
Step 101112: High-pressure circuit leak, high-pressure fuel injection pump phasing fault
Step 1012: P1=P2
Step 10121: Supply system operational
Step 10122: Learning the phasing of the high-pressure fuel injection pump, new P1, P2 values
Step 101221: P1=P2
Step 1012211: Supply system non-operational, high-pressure fuel injection pump control problem
Step 1012212: Supply system operational
| Number | Date | Country | Kind |
|---|---|---|---|
| 15 60341 | Oct 2015 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/001737 | 10/20/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/071797 | 5/4/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5413079 | Laufer | May 1995 | A |
| 5615656 | Mathis | Apr 1997 | A |
| 20050103312 | Uchiyama | May 2005 | A1 |
| 20050103313 | Lemoure | May 2005 | A1 |
| 20060147317 | Okamoto | Jul 2006 | A1 |
| 20090007885 | Serra | Jan 2009 | A1 |
| 20090055082 | Ikeda | Feb 2009 | A1 |
| 20090205413 | Yamauchi | Aug 2009 | A1 |
| 20100280744 | Aubourg | Nov 2010 | A1 |
| 20110116938 | Jung et al. | May 2011 | A1 |
| 20140283790 | Suzuki | Sep 2014 | A1 |
| 20140373812 | Hashim | Dec 2014 | A1 |
| 20170350341 | Courtiel | Dec 2017 | A1 |
| 20180128188 | Hirata | May 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 102562336 | Jan 2014 | CN |
| 10136706 | Feb 2002 | DE |
| 102012218766 | Apr 2014 | DE |
| 102014100165 | Jul 2014 | DE |
| 2926110 | Jul 2009 | FR |
| 20110054469 | May 2011 | KR |
| Entry |
|---|
| International Search Report and Written Opinion for International Application No. PCT/EP2016/001737, dated Jan. 20, 2017, 7 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20190063362 A1 | Feb 2019 | US |
