FR2787830A1 - METHOD AND DEVICE FOR CONTROLLING THE FUEL DOSING OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Method and device for controlling the fuel metering of an internal combustion engine. For a first angular position of the crankshaft and / or of a camshaft, first quantities are defined and for a second angular position, second quantities are defined . The first quantities are used to control the next injection. At least one of the second quantities is used to control the next second injection.

Description

I

State of the art.

  The invention relates to a method and a device for controlling the metering of fuel of an internal combustion engine. In known methods and devices for

  fuel metering request for an internal combustion engine

  dull, we use solenoid valves to control the start

and the end of the injection.

Advantages of the invention.

  The object of the present invention is to develop a method and a device for controlling the metering of fuel.

  by calculating the quantities used to control the injection

  in such a way that these quantities are sufficiently available in time before injection, that they are as current as possible, and that previous quantities do not

  are not influenced by a subsequent calculation.

  To this end, the invention relates to a method of the type defined above, characterized in that: - for a first angular position of a crankshaft and / or of a camshaft, first quantities are defined and for a second angular position, second quantities are defined, - the first quantities are used to control the next injection and at least one of the second quantities

  is used to order the next second injection.

  According to other advantageous features of the invention:

  - the first and / or the second angular position are followed

  lives of an interruption which triggers the definition of the first and / or the second quantity, - the quantities define at least a start and / or a duration of the injection, - the first quantities are used to control a first partial injection,

  - the second quantities are used to control a second in-

partial jection,

  - the quantities which define the start of the second injection

  are used to control the second in-

  next jection, - the quantity which defines the duration of the second partial injection is used to control the next injection, - the first partial injection is a pre-injection and the

  second partial injection is a main injection.

  The invention also relates to a device of the type defined above, characterized in that it comprises: - means which, for a first angular position of a

  crankshaft and / or camshaft, define pre-

  better sizes, and which for a second angular position

  areas define second quantities,

  - means which use the first quantities to

  request the next injection, and means that

  minus one of the second quantities to order the se-

next injection.

  Drawings: The present invention will be described below using the embodiments shown in the accompanying drawings in which:

  - Figure 1 is a block diagram of an arrangement

  fuel metering control device,

  - Figure 2 shows different signals represented

tees as a function of time,

  - Figure 3 shows a flowchart to explain

cite the procedure of the invention.

  Description of the exemplary embodiments.

  Figure 1 shows the essential elements of a

  fuel metering control system for a combustion engine

  internal bustion. The control bears the reference 100. It acts on an actuator 110 by supplying it with control signals A. A tone wheel 125 is associated with the crankshaft and / or the camshaft to be detected by a sensor 120 connected to the control 100. Other sensors 130 are provided.

  to generate signals characterizing the operating state

  the internal combustion engine and the environmental conditions

  ronnantes. The sensor 120 provides pulses which occur for certain angular positions of the crankshaft

  and / or the camshaft. These are preferably marks carried by the tone wheel 125 in positions such as 5 at each top dead center of a cylinder of the combustion engine.

  internally we have an impulse. The other sensors 130 are

  consist, among other things, of a sensor providing a signal

  confirming the driver's wish.

  Based on different operating parameters

  The control 100 calculates control signals to act on the actuator 110. Based on the driver's wishes

  of the internal combustion engine speed, the 100 control

  ends a quantity QK which defines the quantity of fuel to be injected. Starting also from different parameters such as for example the quantity of fuel injected QK, we define

  a quantity which fixes the start of the injection. Next to the sou-

  hates the driver and the regime, we can also hold

  account for other quantities characterizing the operating state

  ment of the vehicle and / or the internal combustion engine. By-

  from these quantities which characterize the start of the injection and the quantity of fuel injected, the control calculates the control signals A to act on

actuator 110.

  The actuator 110 is preferably an electro-

  valve or piezoelectric actuator. From the control signal A, the actuator 110 occupies a position such that an injection or not follows. Preferably, a signal is sent setting the start of the command and a signal setting the

end of order.

  The actual injection is frequently sub-

  divided into several partial injections. Preferably

  For each combustion cycle in a cylinder, a small pre-injection and a large main injection are carried out. Besides pre-injection and injection

  main one can foresee other partial injections.

  This is how we can, for example, provide a post-

  injection. It is also possible to subdivide the pre-

  injection, the main injection and / or the post-injection each time in several pre-injections, several injections

  main and / or several post-injections.

  The process of the invention will be described below in the case of the example of the pre-injection and the main injection. The method according to the invention can also be applied to other partial injections. The method according to the invention is applicable when a first and a second partial injection are carried out. In the following we will designate the first partial injection as pre-injection

  and the second partial injection as the main injection.

  To achieve optimal combustion, you must

  that the partial injections are in a defi-

  denies with respect to the top dead center of each cylinder. Notam-

  In the case of diesel engines, the start of the command, both of the pre-injection and of the main injection, must be defined exactly. Pre-injection is triggered in a range of about 95 upstream from top dead center and the main injection in a range of 25

before top dead center.

  In the calculation of the start of orders, sometimes of the pre-injection and the main injection, the quantities injected QK and the average speed N are required. The calculation of the duration of the order both of the pre-injection and of the main injection requires the quantity injected QK and the current injection pressure P.

  The engine speed N remains essentially

  both in the time interval between the pre-

  injection and the main injection. The amount injected QK can vary significantly within this

  period. In particular in so-called "ramp systems"

  mune "in which the fuel pressure corresponds to the pressure prevailing in the rail, the fuel pressure P has a very high dynamic range. This is why it is necessary to

  take into account a considerable variation of this large

  between the pre-injection and the main injection.

  It is therefore necessary that the pre-

  injection and the main injection are calculated at

  different moments. Synopsis must be foreseen

  angle chronos which occur each time for a certain defined angular position of the crankshaft and / or the camshaft. The interruption that the calculation of the quantities of the pre-injection triggers is done preferably at 168 upstream of the top dead center and the interruption that triggers the calculation of the quantities of the main injection is done at 78

upstream from top dead center.

  The significance of pre-injection from the point of view of combustion technique is to precondition the

  combustion chamber for the following main injection.

  This is why it is not important to have a very close relationship.

  precise between the absolute position and the position of the crankshaft-

  quin and / or camshaft but much more the position re-

  lative of the pre-injection compared to the main injection. This requirement is taken into account in that the distance between the start of the pre-injection command and the start of the main injection command is read in a field of characteristics. This means that the start of the ABVE pre-injection command follows from the following formula:

ABVE = ABVR + ABHE

  In this formula, the quantity ABHE corresponds

  at the start of the main injection control and the large

  their ABVR at the distance from the start of the command for the

  pre-injection and main injection.

  The difficulty in calculating the pre-injection for the injection is that the start of the ABHE command for this main injection has not yet been calculated. If we then calculate the start of the main injection command

  with the new operating conditions, this new

  new calculated value from the start of the main ABHE injection

  may differ significantly from the previous value

  used for the calculation of the pre-injection. Under the most unfavorable conditions, this can lead to

  the main injection and the pre-injection are too wide

  ted or significantly too close together.

  Figure 2 shows different quantities of time t. In the first line, arrows pointing downwards identify the instants at which the pulses from sensor 120 occur. The reference OT (K-1) is the top dead center of the cylinder of order K-1; the reference OT (K) designates the top dead center of the cylinder of order K.

  Below, the arrows pointing upwards

  sign the instants at which interruptions occur triggering the calculation of the quantities of the pre-injection and the main injection. In the line below, time intervals have been marked during which the pre-injections

  can occur in the first and second cycles

  lindres. The reference VE (K-1) designates the possible interval

  for pre-injection into the cylinder of order K-1 and re-

  reference VE (K) for the cylinder of order K.

  In the line below are the inter-

  possible values for the main injection HE (K-1) of cy-

  lindre of order (K-1) and the interval for the main injection HE (K) for the cylinder of order K. In the lower line are the zones in which one calculates

  the sizes to control the injection.

  The chronological separation of the two calculations is not possible since the order duration must in particular be calculated as up to date as possible. In addition, at the start of the calculation of the main injection HE (K) of order K, the start of the command ABVE (K) for the pre-injection VE (K) of order K is already fixed; the control signal has already been able

be supplied to the actuator.

  So that in these boundary conditions the

  tance between pre-injection K and main injection K corresponds to the desired value, the start of the

  ABHE (K) command of the main injection HE (K) calculated in-

  continuation is no longer modified with respect to the value ABHE (K-1)

  the main injection HE (Khl) which served as a basis.

  To avoid the interaction of the ABVER distance

  between the pre-injection and the main injection by the cal-

  ass of the main injection, we proceed as it will be

crit below.

  In a first step 300, the pre-

  sence of a top dead center OT. If the interrogation 300 cons-

  tate the presence of such a top dead center, a counter K is increased by one in step 310. The following interrogation 320 checks the presence of a first interruption IR1 (K). In the flowchart of Figure 3, the reference J

  indicates a positive response to a question and the ref-

  rence N a negative response to a query.

  In the presence of this interruption IR1 (K) in step 330, the magnitudes of the pre-injection are calculated. For this, the duration DVE (K) of the pre-injection is predetermined as a function of the quantity of fuel QK injected and of the fuel pressure P. The distance ABVER (K) is predetermined as a function fl at least of the speed N and other factors such as the amount of fuel injected QK. This

  value is preferably extracted from a characteristic field

  ques and / or fields of characteristics.

  The start of the ABVE (K) command of the pre-

  next injection is then calculated from the distance ABVER (K) and the quantity ABHEW (K-1). The greatness ABHEW (K-1)

  is the start of the main injection control, calculated

for the previous injection.

  The following interrogation 340 checks whether the information

  IR2 (K) terruption has occurred. If so, we cal-

  calculates the quantities of the main injection in step 350. The duration DHE (K) of the main injection is predefined as a function of the quantity of fuel injected QK and of the fuel pressure P. Then the new value is calculated ABHEW (K) of the desired command start as function f2 at least of the quantity of fuel injected QK and of the speed N. This quantity gives the desired start of the command of the main injection for which the main injection would be optimal for these Working conditions. Then we calculate the quantity ABHEK (K); this quantity is fixed and equal to the value ABHEW (K-1). The quantity ABHEK (K) corresponds to the quantity controlled by the actuator to trigger the start of the main injection. At the start of the main injection command, the value calculated for the previous injection is used for the start of the command.

  the previous main injection.

  According to the invention, two beginnings of com-

  different commands for the main injection. The first va-

  their ABHEK corresponds to the control signal actually used and takes into account the distance required between the pre-injection and the main injection. The second ABHEW value takes into account the operating conditions modified at this time. But this value is only used as a value

  only for the next injection.

  A first angular position of the crankshaft

  produces a first IR1 interrupt triggering the definition

  tion of the first magnitudes. The first ABVE sizes,

  DVE define the start and / or the duration of the pre-injection.

  The quantity DVE, which defines the duration of the pre-injection, is used for the next pre-injection following the interruption IR1. The quantity ABVE used to control the

  start of the pre-injection is used to control the pre-

  next injection after the interruption.

  The second angular position of the crankshaft pro-

  takes a second IR2 interrupt triggering the definition

  of second magnitude. The second quantities ABHE, DHE defi-

  limit the start and / or duration of the main injection. The quantity DHE, which defines the duration of the main injection, is used for the next main injection following the interruption IR2. The quantity ABHE used to control the start of the main injection is used only to control the next second main injection after the interruption. This means ensures that for the quantities DVE and DHE, defining the duration of the pre-injection and / or the main injection, the most current operating parameters are always used. It also ensures that the distance between the pre-injection and the main injection

corresponds to the desired value.

Claims (9)

R E V E N D I C A T I ON S   1) Method for controlling the metering of the fuel of an internal combustion engine, characterized in that - for a first angular position of a crankshaft and / or of a camshaft, first quantities are defined and for a second angular position, second quantities are defined, - the first quantities are used to control the next injection and at least one of the second quantities   is used to order the next second injection.   2) Method according to claim 1, characterized in that the first and / or the second angular position are followed by an interrupt which triggers the definition of the first and / or of the second magnitude.   3) Method according to claims 1 and 2,   characterized in that the quantities define at least a start and / or a duration injection.   4) Method according to any one of the preceding claims. teeth, characterized in that   the first quantities are used to order a first in- partial jection.   5) Method according to any one of the preceding claims. teeth, characterized in that   the second quantities are used to control a second injection partial tion.   6) Process according to any one of the preceding claims. teeth, characterized in that   the quantities that define the start of the second injection   are used to control the second in- next jection.   7) Process according to any one of the preceding claims. teeth, characterized in that   the quantity which defines the duration of the second injection by   This is used to order the next injection.   8) Process according to any one of the preceding claims.   teeth, characterized in that the first partial injection is a pre-injection and the   second partial injection is a main injection.   9) Device for controlling the metering of the fuel of an internal combustion engine, characterized in that it comprises - means which, for a first angular position of a   crankshaft and / or camshaft, define pre-   better sizes, and which for a second angular position   areas define second quantities,   - means which use the first quantities to   request the next injection, and means that   minus one of the second quantities to order the se- next injection.