FR2772430A1 - FUEL INJECTOR FOR AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Injector comprising a closure member (11) sliding axially in a bore (9) of an injector (1). This member (11) has a sealing surface (27) cooperating with a valve seat surface (29) in the body (1). An ejection orifice (45, 46) provided in the wall of the body (1) can be partially or totally opened by the sliding of the closure member (11); a control rod (30) terminates at its side opposite to the closure member (11) in a control chamber (40) receiving pressurized fuel, with an outlet to a return line (50) provided with 'a throttling member controlled by a solenoid valve (60). The control chamber (40) has another lateral outlet to the return pipe (50), equipped with a throttle member (42).

Description

STATE OF THE ART The present invention relates to a injector for

  fuel for an internal combustion engine comprising a shutter member sliding axially in a bore of an injector body, this shutter member having a sealing surface cooperating with a valve seat surface in the body injector, at least one ejection orifice in the wall of the body of the injector, this injection orifice being able to be opened partially or completely by the sliding of the shutter member as well as a

  control rod coaxial with the obturation and sliding member

  seated by the latter, this rod ending in its side opposite to the shutter member in a control chamber receiving fuel under pressure, the control chamber having a

  outlet to a fuel return line with an or-

  throttle valve controlled by a solenoid valve.

  We know for example according to the document DE-

  196 45 900.1 a fuel injector comprising a shutter member sliding axially in the bore of an injector body; this member has a sealing surface cooperating with a surface forming a seat of the body of the injector; the injector has at least one orifice

  ejection into the wall of the body, orifice which closes by

  partially or totally by translation of the organ

shutter.

  In this injector, the ejection ports are

  preferably distributed one above the other axial-

  ment in two rows and the opening movement of the shutter opens them successively. The difficulty of this solution is to control the opening stroke in a technically simple manner, since this opening stroke of the shutter member depends on the opening pressure applied to the shutter member. . In particular, the opening movement cannot be stopped if the opening pressure applied to the shutter member

continues to increase.

  Document DE-196 19 523.3 describes an injector

  of fuel for internal combustion engines in the-

  which the opening movement of the shutter member is controlled by electromagnetic means. This injector

  fuel applied to internal combustion engines

  carries a shutter member sliding axially in a bore of the injector body with a sealing surface which cooperates with a valve seat surface provided in the body of the injector. A control rod coaxial with the shutter member is slid by it; on the side not turned towards the shutter member, this rod arrives in a control chamber put under the fuel pressure;

  this control chamber has an outlet to a connection

  fuel return line with a throttle valve controlled by a solenoid valve By controlling the solenoid valve, the outlet is opened so that the fuel in the control chamber can escape through the throttle valve in the fuel return line. The difficulty with this solution is that the electrical control of the solenoid valve allows only full opening of the injector. A partial opening of the ejection orifices of the body of the injector by, for example, brief control of the solenoid valve again leads to a rise in pressure,

  then closing the injector needle.

  The object of the present invention is to develop a fuel injector corresponding to the type defined above for an internal combustion engine, the construction of which is simple and which makes it possible, compared with conventional injectors.

  of comparable size, arriving at an injection section

  precise, adjustable in steps.

  Advantages of the invention To this end, the invention relates to a fuel injector of the type defined above, characterized in that in

  the control chamber has at least one other outlet

  to the fuel return line this outlet

  being equipped with another throttling organ that can close

  sea by sliding, the control rod.

  Thanks to at least one other outlet, lateral for the fuel return line, with another throttling member, a stroke stop which is freely controlled is obtained in a particularly advantageous manner and as will be described below. for the obturation organ

  and thus a controlled release of one or all of the orifications

  these ejection, depending on the operating point of the internal combustion engine. The controlled ejection section of this

  way significantly improves the quality

  gas emission from the internal combustion engine.

  Strictly speaking, the establishment of at least one ejection orifice in the wall of

  the shutter member can be done in different ways.

  An advantageous embodiment provides at least two ejection orifices in the wall of the body of the injector, these orifices being axially arranged one above the other to open successively during the sliding of

the shutter member.

  Preferably, there are not only two ran-

  ejection orifices but a large number superimposed in the axial direction of the shutter member, and which are released by the shutter member ensuring the function of a drawer, after passage of a certain stroke empty. It is clear that, as an alternative to these two rows of ejection orifices, it is also possible to provide more than two rows of ejection orifices as well as any arrangements and constellations of such rows of ejection orifices.

  To allow an opening stroke at two levels

  calves with two holes or rows of ejection holes, su-

  side by side, it is advantageously provided that the total length of the sliding assembly formed by the shutter member and the control rod is greater than or equal to the axial distance between at least one upper ejection orifice turned towards the control rod and another side outlet, and that this length is less

  at the axial distance between at least one internal ejection orifice

  lower not turned towards the control rod and this other

lateral exit.

  To always ensure that the control chamber is filled with fuel, it is preferably provided that this chamber can be filled with pressurized fuel during the injection breaks. 5 Drawings The present invention will be described below in more detail with the aid of an exemplary embodiment shown diagrammatically in the appended drawings, in which: FIG. 1 is a sectional view of an exemplary embodiment of a fuel injector according to the invention, - Figure 2 schematically shows the stroke of the shutter member as a function of time for the injector

  of fuel shown in Figure 1.

  Description of the exemplary embodiment

  The example of realization of a fuel injector

  rant according to Figure 1 comprises a body 1, the lower end, free enters a combustion chamber not

  depicted of an internal combustion engine supplied with fuel

  burant. At its upper end, away from the combustion chamber, the body 1 of the injector is tightened using a nut 3, axially against a support body 10. The injector body 1 comprises a blind bore 9 starting axially from its upper front surface and housing in axial sliding a shutter member 11 in the form of a piston; the lower end of this closure member enters the area of the injector body 1 on the side of the

  combustion and its other end, not turned towards the

  bre of combustion, penetrates with a rod 13 of diameter

  duit, in a spring chamber 15 provided in the support body 10. An injector spring 17 prestressed in this spring chamber 15 is supported by its upper end, opposite the shutter member 11 against a shoulder of the housing in chamber 15; by its lower end, the spring acts via a spring cup 19

  against the shutter member 11. In the example of realization

  tion shown in Figure 1, there is provided a single spring

injector 17.

  The shutter member 11 is guided by its end

  upper miter tightly in the bore 9 of the body

  Injector 1. In the area of a pressure chamber 21 for-

  driven by an extension of the bore 9, this closure member comprises a thrust shoulder 23 which corresponds to the reduction in the diameter of the closure member 11 towards the combustion chamber and against which the upper acts

  fuel pressure in the opening direction, i.e.

  say axially upwards according to Figure 1 on the organ

  shutter 11. The high fuel pressure in the chamber

  pressure bre 21 is transmitted by a pressure channel 25 which passes essentially axially through the injector and to which is connected an injection pipe not shown, connected to a pressure adjustment 26; this conduct is

  connected to a fuel injection pump not shown.

  Below, i.e. downstream of the shoulder

  pressure 23, the shutter member has a narrowing

  conical ment of the section which forms a sealing surface 27 cooperating with a conical, opposite valve seat surface 29 provided on the injector body 1; this surface is produced on a reduction in diameter of the hole 9. Downstream

  of the sealing surface 27, there is a cylindrical extension

  as on the shutter member 11 which forms a piston slide 31 guided in leaktight manner in a segment 33 of the bore 9 adjacent to the valve seat 29 and whose free front surface 35 delimits a fuel chamber 37, with the closed end of the injector body 1 on the side of the combustion chamber. The fuel volume 37 is connected by a longitudinal bore 39 extending axially from the front surface 35 and a transverse bore 41 intersecting the bore

  longitudinal, communicating with an annular volume 43 direct

  adjacent to the valve seat surface 29.

  The lower end of the injector body 1, on the side of the combustion chamber has ejection orifices 45, 46 which start from segment 33 of the bore 39 and

  open into the combustion chamber of the combustion engine

  internal fuel supplied; we preferably have two

  axially superimposed rows of ejection orifices 45, 46.

  The inlets of the ejection orifices 45, 46 in the wall of the drilling segment 33 are closed in a sealed manner by the periphery of the drawer / piston 31 when the shutter member 11 is applied against the seat 29. In this case, the injector is closed. The annular edge formed on passing from the front surface 35 to the envelope surface of the piston slide 39, constitutes a control edge for the shutter member 11

  and the sliding of this organ on this edge by the orifi-

  these injection 45, 46 begins or ends the operation

injection.

  Coaxial with the shutter member 11, it is

  provided a cylindrical control rod 30 connected to the neck

  spring shovel 19; the upper front edge 31 of this rod ends in a control chamber 40 provided in the support body 10 of the injector. The control chamber is stressed by fuel under pressure. The pressure chamber 40 has, at its upper front end, an outlet for a fuel return line 50 with a throttle member 42. The throttle member 42 is controlled by a valve member 62 of a known solenoid valve in itself. The solenoid valve 60 in this case comprises a spring 64 acting in the closing direction and an armature acting on the shutter member 62 of the solenoid valve; when its electromagnet is supplied with current and the solenoid valve is attracted by the excitation of the coil,

  the throttle member 42 opens.

  The pressure chamber 40 is equipped with another outlet 44 provided with a throttling member provided on the side, opening into a discharge pipe 52 and this is

  connected to the fuel return line.

  The operation of the fuel injector re-

  presented in Figure 1 will be described below in conjunction with Figure 2; this figure represents the stroke of the assembly formed by the shutter member 11 and the control rod 30

as a function of time.

  In the rest state, the shutter member 11 and the control rod 30 occupy their position shown in the

  Figure 1. The control chamber 40 is filled with carburetor

  rant; the throttle member 42 is closed. At the start of the injection operation, the fuel under high pressure passes through the pressure channel 25 to reach the pressure chamber 21 and attacks through the pressure shoulder5 23, the shutter member 11 in the sense of openness. When a certain injection pressure is reached, the opening force applied to the shutter member 11 exceeds the closing force exerted by the valve spring 17 and the shutter member 11 is then lifted from its seat 29. High pressure fuel 10 thus passes through the valve seat opened through the holes 41, 39 of the drawer 31 to arrive in the fuel chamber 37; the pressure of the fuel acting on the front surface 35 supports the opening stroke of the shutter member 11, axial, directed in the direction of opening, that is to say inwards according to the figure 1. After having traveled a certain idle stroke, the control edge of the piston drawer 39 passes over the row

  lower ejection orifices 45 whose section controls

  dée, during opening, corresponds to a partial ejection section through which the fuel is then ejected into the

engine combustion chamber.

  This sliding of the shutter member 11 sou-

  at the same time axially lifts the control rod 30 which

  then forms an assembly with the shutter member.

  As then the total length of the assembly covers

  smoothing joint, comprising the closure member 11 and the control rod 30, is greater than or equal to the axial distance between the upper injection orifice 46 and the other lateral outlet 44 provided with a throttling being less than the axial distance between the lower injection orifice 45 and the lateral outlet 44, provided with the throttling member, the peripheral wall of the control rod 30 completely closes the lateral outlet 44 with the throttle when the control edge of the piston drawer 31 is between the ejection orifice

  lower and the upper ejection orifice 46.

  The axial sliding of the control rod 30 then pushes the fuel which is in the chamber

  control 30 through the throttle member 44 in the con-

  return line 52 until the peripheral wall of the control rod 30 closes the lateral outlet with the member

throttling 44.

  As soon as the lateral outlet 44 provided with the throttle member is closed, the hydraulic travel stop acts and stops the control rod 30 and with it

  the shutter member 11 until the solenoid valve 60 or

  see the outlet fitted with the throttling member 42 in the side

  tee of the control chamber 40; the fuel in the control chamber 40 can then escape through this other

  outlet in the fuel return line 50.

  The lateral outlet fitted with the foreign member

  regulation 44 in the control chamber 40 allows the ma-

  described above, to adjust a partial stroke pre-

  and thus the command to open a section

  partial. The chronogram of this partial race which

  vre only the opening 45 is shown in Figure 2 under the reference I. It is clear that the outlet with the organ

  throttle 42 provided in the front face can be or

  green by the control of solenoid valve 60 already from the start of injection. The chronological sequence of such a maximum stroke (reference II in FIG. 2) thus controls in a rapid succession both the ejection orifice 45

and the ejection orifice 46.

  It is also possible, as shown by the curve of the stroke as a function of time (reference III), that

  the shutter member 11 firstly runs a stroke

  tielle, then a maximum race after a given period.

  In this case, we first have an ejection section

  tial by the opening of the lower ejection orifices 45, then the entire ejection section is released by the control on opening, by opening both the lower ejection orifice 45 and of the ejection port

higher 46.

  It is particularly advantageous if the com-

  The nozzle section can be chosen in any way and can be adapted to the operating point of the internal combustion engine within the range of engine characteristics. The stroke stop thus operates independently of the injection pressure. By the sec-5 tion of passage of the two throttling members 42, 44 and the phase angle of the control rod 30, it is further possible

  influence the opening characteristic of the shutter member 11. In case of stronger throttling, the shutter member will open more slowly.

Claims (5)

R E V E N D I C A T I O NS   1l) Fuel injector for an internal combustion engine   dull comprising a shutter member (11) axially sliding   Lement in a bore (9) of an injector body (1), this closure member having a sealing surface (27) co-operating with a valve seat surface (29) in the body injector (1), at least one ejection orifice (45, 46) in the wall of the body (1) of the injector, this injection orifice being able to be opened partially or completely by the sliding of the shutter (11) and a control rod (30) coaxial with the shutter member (11) and slid by it, this rod ending on its side opposite to the shutter member (11) in a control chamber (40) receiving fuel under pressure, the   control chamber having an outlet to a return line   fuel tower (50) with a throttle controlled by a solenoid valve (60), characterized in that in the control chamber (40) has at least one other lateral outlet to the fuel return line (50) , this outlet being equipped with another throttling member (42) which can be closed by sliding, the control rod (30). 2) injector according to claim 1, characterized in that the wall of the body (1) of the injector comprises at least two   ejection ports (45, 46) superposed axially for   see be opened successively by the sliding of the shutter member (11).   3) An injector according to claim 2, characterized by several rows of ejection orifices, superimposed in the axial direction of the closure member, these rows of ejection orifices being released by the closure member, successively after the passage of a certain empty run.   4) An injector according to any one of claims 1 to   3, characterized in that the total length of the overall sliding assembly formed by the shutter member (11) and the control rod (30)   is - greater than or equal to the axial distance between-   be at least one upper ejection orifice (46,) directed towards the control rod (30) and another lateral outlet (44), opening into the pressure chamber (40) and - less than the axial distance between at least one lower ejection orifice (45), not turned towards the control rod (30) and the other lateral outlet (44) in the control chamber (40).   5) An injector according to any one of the pre- claims   , characterized in that during ejection breaks, the control chamber (40) receives fuel under pressure.