FR2783879A1 - FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES - Google Patents

Abstract

Fuel injector for internal combustion engines comprising an injection member (40) slidable axially in a bore of an injector body (20), which has a sealing surface, through which it cooperates with a seat disposed on the injector body (20), and with at least one injection port, which can be controlled during the lifting movement of the injection member by lifting the sealing surface of the injector from its seat, the injection opening being provided in the wall of the injector body (20) and an inlet opening of the injection orifice which can be closed by the lifting movement of the member d 'injection.Concentrically to the injector body (20) an annular slide (50) partially closes the injection opening in its starting position, and can slide in the axial direction to release the entire cross section of the injection opening.

Description

STATE OF THE ART The invention relates to a fuel injector

  for internal combustion engines.

  A fuel injector for engines with

  internal bustion emerges for example from document DE-196 45 900-A1. This fuel injector has an injection member which can slide axially in a bore of an injector body with a sealing surface, with which it cooperates with a seat surface on the injector body, and with minus one injection orifice, which during the opening stroke of the injection member can only be controlled after having traversed a determined no-load stroke and after the lifting of the sealing surface of the injector from the seat thereof. The injection opening is provided in the wall of the injector body, an inlet opening of the injection opening can

  be closed by the injection device.

  In order to be able to comply with limit values

  emissions and noises in the case of Die-

  direct injection salt, it is necessary to have, in particular to obtain a superimposed injection of diesel

  and water (what is called a two-fluid injection)

  fuel contents including the injection cross section

  can be changed depending on the operating state.

  The object of the invention is to develop injections

  fuel teurs opening inside, in such a way

  that the injection cross section can be changed.

  Advantages of the invention This problem is solved in the case of a fuel injector of the type described at the start according to the invention. Thanks to

  annular drawer which concentrically surrounds the

  jection and which closes in its starting position the injection opening in part and which can be slid in the axial direction to release the entire cross section of

  the injection opening, it is possible to have a

  easy to carry out from a technical point of view a modifiable cross section for safe operation in the case

  a fuel injector open inward.

  The annular drawer can therefore be placed under

  pressure in an advantageous way via a

  separated in such a way that it clings to its starting position when it is supplying fuel under pressure and that it can slide, when

  the removal of fuel under pressure, at the

  against a restoring force in the axial direction.

  The injector seat consists of a ma-

  advantageously on a sealing head which is arranged with a small radial clearance in the injector body. Thanks to this radial clearance of the sealing head, it is possible to compensate for a

  very advantageously the mounting tolerances of the gold-

  injection pipe, because the sealing head adapts to the

  injection line and not vice versa - as in the case of

  injectors known from the state of the art - gold -

  injection valve at the sealing seat.

  For this, the injection device preferably presents

  rence a convex, ball-shaped surface forming the surface

  sealing face of the injector at its end, located on the side of the combustion chamber, surface with which it cooperates by a sealing edge of the sealing head of annular shape, which circles all around, and which forms the seat

of the injector.

  The injection device can lift upwards.

  against a restoring force, so

  that it is not subject to any external soiling.

  In particular, the sealing seat is in this case disposed inside the fuel injector and is

  thus protected against any soiling due to combustion gases-

  tion. To control the injection cross section, it is advantageously provided that an annular edge forms, on the passage between the peripheral wall of the annular slide and its front face, a control edge which determines in passing

  on the inlet opening of the injection opening the sec-

  transverse opening of the fuel injection. Of

  this way we can make different cross sections

  fuel injection, by obtaining in advance

  ensures that variations in the angle of the injection jet do not occur due to an annular drawer located inside and partially covering the injection opening, as strongly as an overlap at the outlet from the information hole

  jection, so that the angle at the top of the injection jet

tion is stable.

  Other advantages and interesting features-

  health of the invention are presented in the description, the

  the following drawings and claims.

  Drawings The present invention will be described below in more detail on the basis of an embodiment, represented in the appended drawings, in which:

  - Figure 1 shows a fuel injector nozzle in po-

  closed position, - Figure 2 shows an enlarged representation of the lower area of the fuel injection nozzle shown in Figure 1,

  - Figure 3 shows the fuel injection nozzle shown

  felt in FIG. 1 in a partially open position, FIG. 4 shows an enlarged representation of the area designated by IV in FIG. 3,

  - Figure 5 shows the fuel injection nozzle shown

  shown in FIG. 1 and in FIG. 3 in a fully open position, - FIG. 6 shows the area designated by VI in FIG. 5 according to an enlarged representation, and - FIG. 7 schematically shows a fuel injection system with common rail (common rail),

  in which the fuel injection nozzle is used

  lon the invention, shown in Figures 1 to 6.

  Description of the exemplary embodiments

  A "common rail" injection system

  tation "(common rail), shown in Figure 7 includes a fuel tank, on which a filter and a pump

  pre-supply as well as a high pressure pump

  go into a distribution rail (Rail) 5 for pressurized fuel. At the distribution ramp 5 are connected to the

  by means of two-way valves 6 via a con-

  control line 12 as well as via a

  injection nozzle 13 of the fuel injectors 10, which will be described below in more detail. From the fuel injectors 10 as well as from the valves 6 the

  fuel flowing back goes to tank 1 through the

  through a return line 14.

  In the pipe there is also a pressure limiting valve 8 and a pressure sensor 4. The output of the sensor 4 leads to a control device 7, which controls both the high pressure pump 3 and the

  valve 6. Other detector signals 9 are furthermore enabled.

born on the control unit 7.

  We will describe in more detail using the figures

  1 to 6 a fuel injector and its operation.

  A fuel injector includes a body

  nozzle 20, which is fixed by means of a clamping nut 22 on a support 30 for fixing the injector. In the injector body 20 there is an injection member 40 so as to

  what it slides axially. The injection organ is ter-

  mine, at its end located opposite the com- position chamber

  bustion, by a pressure piece 41, and is held by the force of a return spring 42 in its starting position

  closed shown in Figures 1 and 2. The injector

  tion 40 has a fuel line 44 disposed at the

  center, which ends in a spring chamber 45 of the res-

  exit 42. The pressure part, which is connected to the injection member 40, has a bore which is in alignment

with fuel line 44.

  The injection member 40 is surrounded so as to

  centered by an annular slide 50 which is held equally

  ment by the return force of a return spring 52 in its starting position shown in FIG. 1 and in FIG. 2. The annular slide 50 can slide in the axial direction until it comes into contact, against the return force of the return spring 52, against a stop, which is arranged on a stop element 55, which also surrounds

  concentrically the injection member 40.

  In the stop element 55 as well as in the sup-

  fixing port 30 of the injector, a control line 60 can supply pressurized fuel to the annular slide 50. To ensure the locking in rotation, a safety pin 70 is also provided for passing between the body. injector 20 and the attachment support 30 of the injector. At its end, located on the side of the combustion chamber, the injection member 40 has a sealing seat 80,

  consisting of a sealing head 81, fixed with a clearance

  very weak dial at the front end of the injector body

  , and by a convex surface 82, in the form of a ball, constituted

  killed on the injection member 40. The sealing seat itself

  even is formed by a linear contact between the surface con-

  vex in the shape of a ball 82 and one of the edges 83 turned towards

  this of the sealing head 81. Like the sealing head

  cheity 81 is mounted with a very small radial clearance ex-

  front end, of the injector body 20, it can compensate for the mounting tolerances of the injection member 40. In this case the sealing head 81 adapts to the member

  injection 40 and not - as is the case for injections

  fuel teurs known per se, - conversely the injection member 40 to a sealing edge which is constituted

  in one piece on the injector body 20.

  The operation of the fuel injector re-

  presented in FIGS. 1 and 2 is then the following: When the control line 60 is open, the pressure force of the spring 52 is reinforced by the pressure which prevails in the control line, so that the

  annular slide 50 is pressed on a shoulder 29, consisting of

  killed on the injection body 20. As soon as the valve 6 opens in the injection line 13, the fuel which is under pressure arrives via the spring chamber 45 of the compression spring 42 through the pressure piece 41 and the fuel line 44 in a cavity which is formed above the sealing head 81 at the end situated on the side of the combustion chamber. On reaching the opening pressure the injection member 40 lifts from the sealing seat 80, the fixing support 30

  of the injector serving as a stop. Fuel flows from one or

  injection groove 90, formed in the injector body 20, in the combustion chamber of the internal combustion engine

dull (not shown).

  The annular edge at the passage between the peri-wall

  spherical 50 and its front surface 52 forms a com

  strip 51 which partially covers the injection opening 90, so that the cross section of the injection opening 90 is only partially released and does not inject

  therefore only a partial amount of fuel.

  In this state the sealing head 81 is blocked in its position by the fuel pressure. When the injection time has elapsed, the valve 6 in the injection line goes to its closed position. The injector

  fuel is pressureless. In this case, the injection organ

  tion 40 is pressed by the compression spring 42 on the

sealing head 81.

  To fully open the fuel injector, the pressure in the control line 60 is dropped through the valve 6 by connecting the control line 60 to the

  return line 14. Valve 6 in the injection line

  tion 13 opens. Fuel is again transferred via the spring chamber 45 of the compression spring 42 and via the pressure piece 41 via the fuel line 44 into the injection member 40. When the pressure is reached, the organ

  40 rises from the sealing seat 80, the support

  injector fixing port 30 again serving as a

  tee. The injection pressure then acts on the front face 52 of the annular slide 50 of annular shape. The force exerted on the annular slide 50 is in this case greater than the force of the compression spring 52, so that the annular slide 50 moves towards the stop formed on the stop element 55. In this position

  the control edge 51 of the annular slide 50 exceeds the

  injection groove 90 in the injector body 20 and releases it completely. When the injection time has elapsed, the valve 6 in the injection line 13 switches to its closed position. The system is pressureless. The injector body 20 is pressed on the sealing head 81. The force of the compression spring 52 puts the annular slide 50

  in the return position on the shoulder 29 on the body of the

jector 20.

  The fuel injector described above has the

  very great advantage that only the injection device or the

  injection nozzle 40 is pressurized. It appears from this that there is a very low risk of organ rupture

  40. However, when damage occurs-

  ment, for example due to a rupture, the construction closes

  the fuel injector prevents damage to the

internal combustion engine.

  Like all the moving parts

  found inside the injector body 20, one can ex-

  close the risk of charring. It is also particularly

  rely advantageous that the injection angle is determined by

  the injector body and that it does not change when

  injection port opening 82.

  By providing the annular drawer 50 it is in-

  be possible that the stop of the stroke of the injector member

  tion 40 is constant, so that its manufacture and

  its mounting are significantly simplified.

REV E N D I C A T I ON S

  1) Fuel injector for internal combustion engines

  dull comprising an injection member (40) which can slide

  be axially in a bore of an injector body (20), which has a sealing surface, by which it co-operates with a seat (80) disposed on the injector body (20), and with at at least one injection port (82), which can be controlled during the lifting movement above

  opening of the injection member by lifting the over-

  sealing face of the injector from its seat, the opening

  of injection (82) being provided in the wall of the injector body

  tor (20) and an inlet opening of the injection orifice (82) which can be closed by the lifting movement of the injection member, characterized in that

  concentrically with the injector body (20) an annular drawer

  the slide (50) partially closes the injection opening (82) in its starting position, and can slide in the axial direction to release the entire cross section of

the injection opening (82).

  2) Fuel injector according to claim 1, characterized in that the annular slide can be fed through a separate control line (60) by fuel being under pressure in such a way that it clings to its starting position when supplying fuel under pressure

  and that it can slide in the axial direction during evacua-

  fuel under pressure against

  the return force of a return spring (52).

  3) Fuel injector according to claim 1 or 2, characterized in that the injector seat (80) is formed on a sealing head (81), disposed in the injector body (20)

with little radial clearance.

  4) Fuel injector according to claims 3,

  characterized in that the injection member (40) has at its end situated on the side of the combustion chamber a convex surface, in the form of a ball, which constitutes the sealing surface of the injector, surface by which it cooperates with a peripheral sealing edge of the sealing head, having

  an annular shape, and forming the seat of the injector (80).

  5) Fuel injector according to one of claims 1

to 4, characterized in that

  the injection device can be lifted from its seat towards the

  against a restoring force.

  6) Fuel injector according to one of claims 1

to 5, characterized in that

  an annular edge forms at the passage between the peripheral wall

  risk of the annular drawer and its front face a control edge, which when passing over the inlet opening of

  the injection orifice determines the cross section of

  fuel injection green.