FR2646210A1 - FUEL INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE WITH AIR COMPRESSION, IN PARTICULAR DIRECT INJECTION DEVICE - Google Patents

Abstract

The invention relates to internal combustion engines. In this device, the piston of an injection pump controls the start of delivery and the end of delivery of the pre-injection and of the main injection, with an intermediate injection pause and the injector which is in communication with the injection pump has a stop which limits the pre-stroke of the needle and which stops the needle of the injector only at the time of the pre-injection. Main application: reduction of noise level and exhaust gas emissions in diesel engines.

Description

26462 0

  The invention relates to a device for injecting

  fuel for a compression internal combustion engine

  of air, in particular a device operating in

  positive direct injection, comprising an injection pump

  the pump piston controls the start of discharge and the end of discharge of the pre-injection and

  the main injection, with an injection pause

  calipers, and an injector which is in operative connection with the injection pump.

  injector needle that lifts from its seat to the

  against the force of a compression spring at the moment

  pre-injection and main injection.

  The subdivision of the fuel injection into two separate operations is described, for example, in the

  US-A-2,871,796, according to which initially, we

  jets only a quantity of fuel intended for

  the initiation of combustion while the primary quantity

  fuel is not introduced into the cylinder

  only a short time later; that is, after a period

  of interruption between the pre-injection and the main injection. For this reason, there are provided on the piston of the pump several control edges which cooperate with recesses of the control section provided in the cylinder of the injection pump during a race of

  work of the pump piston. By adopting a pre-injection

  separated from the main injection, the high noise levels of the combustion are lowered and the proportions of harmful substances emitted in the

  exhaust. However, it has been found that the

  such injection sites no longer meet the specifi-

  current fictions concerning the production of noise and

  exhaust emissions because small injections

  necessary for the needs of the internal combustion engine

  can not be obtained at the time of the in-

  pilot, because of the strong variation that the pilot quantity undergoes with the variation of the speed of

  rotation of the motor. The origin of this undesirable variation

  the quantity of the injector needle that opens up to a more than proportional section width, even in the presence of pressure

  just reach the opening pressure.

  One can certainly find the way to reduce the noise of combustion by shortening the useful stroke but this leads to a change in the point of attack of the pre-injection pump or the beginning of the pre-injection,

  with the result that the pilot injection does not become

  only in the high speed range of the engine, but in the low speed range, which has a detrimental effect on combustion noise and gas behavior.

exhaust.

  The object of the invention is to exercise a

  influence on the course of the injection thanks to

  special influence, which will lead to a considerable improvement in noise and gas emission behavior

  exhaust of the internal combustion engine.

  According to the invention, this problem is solved by the fact that a stop provided in the injector and which limits the pre-stroke of the needle of the injector, stops the needle of the injector until the break injection, this stop

  being able, however, to give in after the break

  in the course of the main injection which

  includes pre-race and main race.

  Thanks to the characteristics according to the invention,

  can be pre-injected with a small amount of

  fuel pressure and which is constant over the entire range of values of engine rotational speed and load, as is necessary for

  get the most out of today's internal combustion engines.

  Due to the arrangement of the stop which influences only the pilot quantity, the needle of the injector is stopped at a very small pre-stroke, so that a very small pilot quantity can be produced, which remains approximately

  constant on all values of rotational speed

  which is insensitive to the fuel temperature.

  as is essential to get the performance

optimal engine.

  DE 36 10 658 AI already discloses an

  jector having an injector needle, wherein

  the opening pressures of the injector model the de-

  of the injection in such a way that

  duise a main race that immediately follows the pre-race. With this measure already known, it does not perform a separate pre-injection of the main injection

  but, on the contrary, a modeling of the course of the injection

  tion in order to be able to adjust the

  very precise on a desired value and by simple means.

  from the point of view of the manufacturing technique.

  According to another characteristic of the invention, the longitudinally guided spring bearing surface constitutes at the same time a guide pin for a

  pressure rod which cooperates with the injection needle

  which, together with the injector needle,

  works in antagonism with respect to the com

  pressure acting as a pre-injection spring during the

pre-injection stroke.

  According to another characteristic of the invention, the pre-injection and main injection springs

are arranged coaxially.

  The invention is described in more detail

  in the following about an example of a repre-

felt on the drawings.

  In these drawings, FIG. 1 represents the injection device

  of fuel consisting of the fuel injection pump and the

ejector;

  FIGS. 2a to 2d represent different po-

  the piston of the pump, in an enlarged representation; FIG. 3 represents a detail of the injection pump on a greatly enlarged scale; FIG. 4 represents the progress of the quantity of pre-injection as a function of the speed of

rotation of the motor.

  FIG. 1 shows a fuel injection device essentially consisting of an injection pump 1 and an injector 2 for an air-ignition internal combustion engine with self-ignition,

  this device constituting a di-

  rect. The injection pump 1 contains a pump piston 4 provided with a boss 3 placed in the high position, this piston having control edges for the pre-injection and

  the main injection, which are formed in

  opposed parts 5, 6 of the section of the piston 3, as well as control orifices 7, 8 formed in the cylinder 9

pump.

  In FIG. 2a, the piston 4 of the pump assumes a position which corresponds to the beginning of the discharge of the pre-injection, in which the communication between the working chamber 10, the recesses 5, 6 of the section

  and the control orifices 7, 8 is interrupted.

  Figure 2b shows the end of discharge of the

  pre-injection. The upper control edge 5a of the

  5 of the section is at the same height as the control edge 12 formed by a step 11 in the

cylinder 9.

  The position of the piston 4 of the pump which is re-

  shown in Figure 2c corresponds to the international discharge

  mediator or at the injection pause. Here, the communication between the working chamber 10 of the pump, the recess 5 of the section and the control port 7 is restored. In FIG. 2d, the end of the injection pause is shown since the closed section recess

  the control port 7 by its lower control edge

  5b. The main injection begins and continues until the oblique control edge 5c establishes communication between the working chamber 10 and the orifice

  8 by means of a longitudinal groove

  13 and an annular space 14 which are provided on the

piston 4 of the pump.

  The injection pump 1 is in communication via a pressure line 15 with the injector 2, which is composed of the mounting body 16, serving as support for two springs, the nut 17 for clamping the injector, the injector body 18 and the injector needle 19. A

  compression spring which acts as a spring of pre-

  injection 20 applies the needle 19 of the injector on its seat via a pressure pin 21 and a pressure rod 22. The pressure rod 22 which is

  resting on the back side of the needle 19 of the injection

  is guided, on the one hand, through a fixed guide washer 23 and, on the other hand, through a

  spring 24 which constitutes a suspended stop which is

  view at the same time as a support for a

  main jection 25, which constitutes the second compression spring. The spring seat 24 is permanently resting on the body 18 of the injector and has a recess 26 directed towards the needle and in which

  needle 19 dives when you reach the pressure of

  Verture. The bottom surface 26a of the recess 25 limits the stroke of the needle 19 of the injector. The spring

  main injection 25, which is based on the

  fixed guide 23, surrounds the compression rod 22. With this embodiment, the pre-stroke corresponds to the pre-injection while after the injection pause, the pre-race and the main race that follows immediately form the total race that gives

the main injection.

Mode of action:

  As soon as, in the unfolding of his ascending

  the piston 4 of the pump reaches the position

  2a, which corresponds to the first start of discharge, the needle 19 of the injector is lifted from

  its seat against the force of the spring pre-in-

  jection 20 located in a high position and, after a pre-race

  VH, it abuts against the spring range 24 which behaves initially as a fixed stop. The needle 19 of the injector is thus stopped at the end of a very short stroke during the pre-injection. As is apparent from FIG. 4, a constant pre-injection quantity is obtained over the entire range of values of the rotational speed of the engine, which quantity is represented by the

  curve "a". When the piston 4 of the pump reaches the po-

  2b, the pre-injection is complete (end of discharge) and the intermediate discharge or injection pause (Figure 2c) occurs. The pre-injection spring 20 returns the needle 2 of the injector to its

  closing position. In Figure 2d, we are in

  the end of the injection pause and the main injection begins (second start of discharge). At the same time, the needle 19 of the injector travels the pre-stroke VH against the pre-injection spring 20 and then the main race against the spring

  28. The main injection corresponds to the

  therefore, to the total race GH which consists of the first

VH race and the main bear.

  VH race and main race.

at

Claims (5)

R E V E N D I C A T I 0 NS   A fuel injection device for an air compression internal combustion engine, in particular a device operating as a direct injection device, comprising an injection pump whose pump piston controls the start of discharge and the end of   repression of pre-injection and primary injection   with an intermittent injection pause, and an injector which is in operative connection with the pump   injection. this injector comprising a needle of   jockey who lifts himself from his seat against the   force of a compression spring at the time of the pre-in-   jection and the main injection, characterized in that a stop provided in the injector (2) and which limits the   pre-stroke of the needle (19) of the injector, stop the   guille (19) of the injector until the injection pause, this stop being however able to yield after the   injection pause in the course of the primary injection   which includes the pre-race and the main race.   Fuel injection device according to claim 1, characterized in that the suspended stop is constituted by a spring seat (24) serving   support for a main injection spring (25).   3. Fuel injection device according to   claims 1 and 2, characterized in that the scope of   longitudinally guided spring (24) constitutes at the same time a guide sleeve for a rod of   pressure (22) which cooperates with the needle (19) of the injection   and which, together with the needle (19) of the injector, works in antagonism with respect to the compression spring serving as a pre-injection spring   (20) during the pre-injection stroke.   4. Fuel injection device according to   Claims 1 to 3, characterized in that the surface   front of the spring bearing (24) which is directed towards the needle has a recess (26) in which is located. recessed, the bottom surface (26a) which stops the needle (19) of the injector at the end of the pre-injection stroke. 5. Fuel injection device according to   Claims 3 to 4, characterized in that the springs   pre-injection and main injection (20; 25) are arranged coaxially.