FR2699225A1 - Installation to adapt the amount of fuel injected into a heat engine. - Google Patents

Abstract

a) Installation to adapt the quantity of fuel injected into a heat engine. b) Installation characterized in that the adaptation is made by varying the injection time and the fuel pressure and in that the fuel mixture consists of premium fuel and methanol and a sensor measures one of the components , preferably methanol, the sensor being provided at a variable location where it comes into contact with the fuel.

Description

i "Installation to adjust the amount of fuel injected into a

thermal motor"

  The present invention relates to an installation

  intended to adapt the quantity injected into a heat engine using fuel mixtures

  different compositions and in particular an installation

  to adapt the amount of fuel injected into a heat engine using fuel mixtures of varying compositions,

  including a fuel pump which supplies the fuel

  injectors, a pressure regulator for

  influence the fuel pressure and an installation

  calculation which provides the necessary control signals

  necessary, as well as means to determine the

fuel composition.

  In such a heat engine, the fuel

  is supplied to the injectors by a fuel pump.

  The fuel pressure is regulated by a pressure regulator and the duration of the injection pulses is set by the control unit according to the demand.

  provides different means, for example a sensor that determines the methanol content, fuel. An analogous method of adapting the quantity

  injected into a combustion engine using fuel mixtures of variable compositions is

  known from DE-OS 40 19 083.

  however, it is necessary to guarantee the adjustment of the quantity of fuel supplied according to the composition of this fuel.

  supplied by the fuel pump according to the

  As in this known method, the pressure established by the fuel pump substantially corresponds to a predetermined pressure,

  the quantity of fuel injected is only defined

  denies by the opening time of the injectors.

  If one wants to use fuels with a very variable composition, it is necessary that the duration

  injectors is very variable and

  is an extended range that can not, however, be

  to have any dimensions so that the regular

  tion of the quantity injected which is exclusive

  by the duration of the injectors' opening, is

more sufficient.

  The object of the invention is to remedy these problems.

  and is concerned with an installation of the type

  nor above characterized in that the adaptation is done by varying the duration of injection and the

fuel pressure.

  The installation according to the invention offers the

  advantage of allowing the adaptation of the quantity

  jected, in a very wide range; this adaptation can be done for the two types of injection currently existing namely intermittent injection for

  the amount of fuel is adequate, has

  constant fuel injection, by varying the duration of injection and, in the case of a continuous injection with a constant injection duration, the change in the quantity of fuel injected is done by variation

the fuel pressure.

  This result is obtained according to the invention in that the quantity injected is adapted both by variation of the duration of injection and by variation of

the fuel pressure.

  The adaptation of the injected quantity is advantageously done with the aid of a coimand apparatus or

  a microcontroller which also contains the

  very operating parameters of the engine

  such as temperature, rotational speed

  air flow, idling,

  full load, thrust operation and others.

  The detection of the fuel mixture is advantageously carried out with the aid of a suitable sensor placed for example in the fuel tank and which measures, at the beginning of each use of the heat engine and, if appropriate, continuously, the

  a fraction that represents one of the components of

  rant, for example the alcohol fraction of fuel A

  instead of a sensor measuring the composition of the car-

  In addition, the composition of the exhaust gases can be used to determine the composition of the fuel.

  as it is possible to combine the two variants.

  The quantity injected can be adjusted by

  of the existing fuel mixture, either in

  It is particularly advantageous to react to rapid variations in

  fuel demand by changing the injection time

  tion, and to respond to slow variations by adapting

fuel pressure.

  The present invention will be described hereinafter in more detail with the aid of the accompanying drawings in which

  FIG. 1 is an overall schematic

  essential components for the invention, of a

  injection system of a heat engine.

  Figures 2a-2c show some

  between the quantities of fuel required and the existing fuel mix for different operating conditions of the thermal engine.

  In addition, these figures indicate the range of

  injection time for constant fuel pressure and, in the case of variable fuel pressure, depending on the

fuel.

  Description of the exemplary embodiments.

  Figure 1 schematically shows a system

  supply of fuel in which the fuel

  tank 10 is pumped by the electric pump

  11 through a fuel filter 12 to the accumula-

  A pressure regulator 14 adjusts the fuel pressure available on the injector 15 A damper 16 and a return line 17 return excess fuel in

the tank 10.

  The injector 15 injects the fuel into the

  in the vicinity of the cylinder 18, in the suction pipe 19 of the heat engine The mixture thus formed is ignited by means of the spark plug 20 The entire system is controlled by a control device 21 which is shown only schematically and that emits

  the control pulse for the different elements.

  The pressure regulator 14 is a regulator

  variable pressure transmitter which receives the

  control of the control apparatus 21 for him to request

  to regulate on a desired pressure instead

  of a variable pressure regulator, one can also

  use a number of regulators to ensure regular

  at different pressures.

  To determine the methanol content of the

  fuel when using a methanol / super-

  fuel tank 10 includes a sensor which can also be provided in the fuel accumulator

  under pressure 13 or in one of the supply lines

  tation. The control unit 21 receives other

  magnitudes, for example the speed of rotation N four-

  denoted by a speed sensor 23.

  The control apparatus 21 provides

  control signals to the pressure regulator 14, the injector 15 and the spark plug 20 Other control signals, not essential to the invention, are not

  given in detail; these signals are schematic

by the exit arrow 24.

  The fuel supply facility

  of a heat engine according to FIG.

  use intermittent injections or injections

  The extension according to the invention for adapting

  tion of the quantity injected, can also be

  re using the installation shown in Figure 1 because it is possible to adapt both the fuel pressure and the duration of the injection to arrive at an optimal injected amount This adaptation can be done in steps or bearings, or continuously; it can be modified separately or globally for both the fuel pressure and the duration of the injection. As shown by the relationships represented

  in Figure 2, the optimum quantity of fuel de-

  the composition of the mixture as well as

  operating conditions must be kept

  account that different causes limit the pos-

  possibilities of variation of the injection duration.

  The maximum fuel quantity possible

  is injected by a permanently open injector.

  So, we can increase this quantity to pressure

  constant for small opening times of the in-

  jector, we encounter difficulties of tolerances

injectors.

  Figure 2a shows an example of the quanti-

  optimum fuel efficiency according to the state of

  of the engine and the composition of the fuel

  In the abscissa, the composition of the

  KZU fuel; the position S represents the composition

  fuel consumption for 100% premium fuel; the position M corresponds to the composition of the fuel

  for an alcohol or methanol content of 100%.

  On the ordinate, the amount of fuel MK is shown; LL points represent the mode of

  idling and VL the operating mode

  at full load It should be noted that for pure premium gasoline, both at idle, at the point of

  LL (S), and at full load VL (S), less car-

  for optimum performance and the same conditions as for 100% alcohol or methanol fuel.

LL (M) and VL (M).

  The quantity of fuel actually required is between a minimum value

  corresponding to the idling operation with

  per-fuel (point LL (S)), and a maximum quantity necessary for the dependent mode of operation

  maximum with pure alcohol (point VL (M)).

  The relations according to Figure 2a have been established with a conventional injection system using neither pure premium fuel nor pure methanol For such pure fuels, the amount of fuel required varies around an MS value for the premium fuel and a MM value for methanol; this value is much smaller than the amplitude of variation X

  between the idle mode of operation with

  LL (S) and the mode of operation

  maximum charge with pure methanol VL (M).

  From an injection system designed for usual use with either gasoline or methanol, the limit values for the quantity

  minimum fuel level and the maximum quantity of

  will be shifted to higher values when the engine uses both pure fuels and blends. This behavior stems, among other things, from different combustion characteristics.

various fuel components.

  In the case of an international injection system

  mittent, it is necessary that with a constant pressure of the system, the injection times, that is to say the times

  injectors, be selected proportionately

  When using premium fuel for idling, this results in relatively short injection times; for the operation of the same engine at full load and with methanol as fuel,

  reaches relatively long injection times

  your. This appears clearly in FIG. 2b giving the injection duration t E as a function of the composition of the fuel; point S corresponds to

  pure premium fuel and point M to pure methanol.

  The references LL and VL correspond again to the operation at idle or operation at maximum load. We arrive at relations similar to those of FIG. 2a. The distance between LL (S) and VL (M) is

  again significantly larger than the

  between LL (S) and VL (S) or between LL (M) and VL (M).

  As already indicated, the variation in the duration of injection

  tion can not exceed certain limits in order to

  your reasons; the invention proposes to modify in an injection system both the injection duration and the injection pressure as a function of the composition

  fuel saved by a sensor.

  For example, the fuel pressure can be increased depending on the methanol content of the fuel and the injection times can be varied according to the operating parameters, as well as the injection time can be varied depending on the fuel content. exhaust gas composition The benefit is

  while the injection times can not be re-

  picks from the usual working range so far,

  and that nevertheless it is possible to adapt to

  different characteristics or compositions of the

rant.

  FIG. 2c shows the variation range of the injection time t E for a variable fuel pressure, the injection duration being represented in FIG.

  depending on the composition of the fuel

  mark that the working range corresponding to X,

  LL (S) and VL (M), is considerably reduced by

  compared to the range shown in Figure 2 b.

  this reduction by increasing the fuel pressure for a large fuel demand, using the variable pressure regulator or, if necessary, switching from one pressure regulator to the other. The variation in pressure and duration

  injection can be done in different ways

  this will be explained in some examples given below. At the start of each start of the engine, a suitable sensor measures the fuel composition Depending on the alcohol content, a continuous or step-adjustable pressure regulator is controlled in the system to achieve the desired pressure. in the system In place of an adjustable pressure regulator one can also

  have in the system several pressure regulators

  each of which causes a different pressure in the system. In this case, depending on the

  In alcohol fuel, one activates each time specified-

  one of these pressure regulators with the

control order.

  The measurement of the fuel composition can also be done during the operation of the engine, which makes it possible to detect the filling operations of the fuel tank. In this case also, it is possible to adapt continuously or in a

  staggered system pressure.

  Alternatively or in addition to the measurement, it is possible to adapt the composition of the fuel and thus the necessary pressure of the system, for example by

  function of a known composition of the exhaust gas

  ment or proceed by education.

  re and by adaptation can also be combined

  to set the appropriate pressure in the system.

  For each possibility, the adaptation of the system pressure according to the variable fuel composition is a relatively slow operation while the duration of injection which constitutes the second quantity can be modified in the system if it is necessary to react as a function of rapid changes in demand

  of fuel by the engine.

Claims (1)

CLAIMS) Installation for adapting the quantity of fuel injected into a heat engine using fuel mixtures of variable compositions, installation comprising a fuel pump (11) which supplies the fuel to the injectors, a pressure regulator (14) for influencing the pressure fuel and a computing installation which provides the necessary control signals, as well as means for determining the composition of the fuel, the installation being characterized in that the adaptation is done by varying the duration of the injection and fuel pressure. 2) Plant according to claim 1, characterized in that the fuel mixture is composed of super-fuel and methanol and a sensor measures one of the components, preferably methanol, the sensor being provided at a variable location where comes into contact with the fuel.   30) Installation according to claim 1 or 2, characterized in that the variation of the duration of injection and / or the fuel pressure is continuously.   ) Installation according to claim 3,   characterized in that the variation of the duration of in-   jection and / or fuel pressure is done on several steps.   ) Installation according to one of the claims   tions, characterized in that the variation of the fuel pressure is with the aid of   less a pressure regulator controlled by the plant calculation.   6) Installation according to one of the claims   tions, characterized by several   pressure regulators, each pressure regulator   it adjusts a setting on another value of the pressure and according to the methanol content, the calculation facility activating precisely one of the pressure regulators. 70) Installation according to one of the claims   tions, characterized in that the installation   calculation is part of a control unit.   ) Installation according to one of the claims   tions, characterized in that adaptation   the quantity injected depends on the operating parameters   thermal engine or composition exhaust gas.   ) Installation according to one of the claims   tions, characterized in that adaptation   of the quantity injected is made according to the   variable position of the fuel, by adapting the pressure of the system, and this adaptation is done on   the basis of a rapid change in the demand for   of the engine, by varying the duration injection.