FR2775737A1 - FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Fuel injection device comprising a high pressure pump (1) connected, on the suction side, to a low pressure supply system and, on the high pressure side, to the injector (13). The high pressure transfer is controlled by a high pressure channel (11) provided between the high pressure pump (1) and the injector (13) using a solenoid valve (15) comprising a shutter member ( 21) having a sealing surface (35) cooperating with a valve seat (29) to form a sealing section. The member (21) and / or a sleeve (25) which guides it are made of ceramic material to improve the reliability of the solenoid valve.

Description

State of the art.

  The present invention relates to a fuel injection device for an internal combustion engine equipped with a high pressure fuel pump, the suction side of which is connected to a low pressure fuel supply system and of which the high pressure side is

  connected at least indirectly to a fuel injector

  clogging in the combustion chamber of the combustion engine

  internal, the high pressure transfer being made by a

  high pressure valve provided between the high pressure pump and the fuel injector using an electric valve

  control which comprises an electrically controlled shutter member

  stick, sliding, having a sealing surface by which this member cooperates with a valve seat, fixed,

  to form a sealing section.

  Such a device is already known according to the docu-

  ment EP 0 178 427 B1 concerning a device for injecting

  fuel with a high pressure pump whose vacuum side

  ration is connected to a low pressure supply system

  in fuel; its high pressure side is connected at least in-

  directly to an injector opening into the control chamber

  engine bustion. Between the pump chamber delimited by the piston of the high fuel pressure pump and

  the injector, there is a high pressure channel. In the dispo-

  known fuel injection device, a bypass line

  vation is connected to the high pressure channel. This line leads into the low fuel pressure system and can be closed using an electric shut-off valve.

  ordered. Control of high pressure transfer of fuel

  Rant in the active chamber of the high pressure fuel pump is done by closing the discharge line connected to the high pressure channel through the

electric control valve.

  Thanks to this closure of the discharge line

  load, a high pressure is established during the transfer stroke of the piston of the high pressure pump, in the

  pump working chamber; this high pressure abou-

  tit, via the high pressure channel, to the injector o it produces, as is known, the opening of the injector. The end of the fuel transfer

  high pressure or high pressure fuel injection

  rant in the known fuel injection device is controlled by the opening of the discharge line by the

  electric control valve; then the high car pressure

  burant which prevails in the pump chamber and in the high pressure channel expands through the control valve

  in the low pressure line system.

  The electric control valve which controls the high pressure transfer of the high pressure pump is

  produced in the form of a solenoid valve whose armature

  straightener is connected to a piston-shaped closure member of the control valve and the envelope surface of which comprises a valve sealing surface. The control valve member cooperates via this sealing surface with a fixed valve seat provided on the body of the control valve and forms, between the sealing surface and the valve seat surface, a section d seal that closes the discharge channel. The known component of the control valve of the fuel injection device has the drawback

  to have a relatively large moment of inertia and to

  thus stop very large actuation forces to ensure rapid control times of the control valve. These large actuating forces can however only be achieved by bulky and expensive actuating magnets so that the current actuating magnets do not meet the strict requirements concerning

fast order times.

  Another disadvantage of the known control valve is the wear of the seat which occurs at the surface of the valve seat due to the encounter speeds.

  between the valve member or by erosion removal

  ion caused by impurities in the fuel; this can result in leaks at the level

  of the sealing section and then destruction.

Advantages of the invention.

  The present invention aims to remedy these drawbacks and for this purpose relates to a fuel injection device for an internal combustion engine of the type defined above, characterized in that the member

  shutter of the electric control valve is ceramic

  mique. This fuel injection device has the advantage, compared with the state of the art, of greatly reducing the inertia of the control valve member thanks to its construction in ceramic material. This allows, for comparable geometries of the obturation member, to achieve a reduction in mass of up to 60% compared to

  that of the usual shutter members made of steel. This reduction-

  tion of the mass thus allows very short switching successions or very fast control times for the

  electric control valves without having to magnify the ai-

  actuating mants used for this command. In addition, the wear on the sealing surfaces is considerably reduced

  valve bodies by the use of ceramic materials

  ques. It is particularly advantageous that alongside the realization of the valve member, and thus of the sealing surface of the valve in ceramic material, one realizes

  also in ceramic the surface of the valve seat cooperated

  rant with this organ, which leads to a further reduction

  considerable wear and tear on the valve seal seat.

  To allow this constructive achievement,

  the piston-shaped valve member is advantageously guided-

  longitudinal sliding in a ceramic sleeve

  that, itself housed in a hole in the valve body. This is particularly advantageous since the high pressure transfer by the high pressure pump is ensured by an electric control valve provided directly in the high pressure channel, between the high pressure pump and the injector. Another advantage of the use of control valve members and / or sleeve forming seats, made of ceramic material, results from their simpler manufacture by a

  compression molding process.

  The embodiment according to the invention of the control valve member and of a sleeve forming a valve seat in ceramic material not only offers the advantage of the use of a pump-pipe-nozzle assembly described in exemplary embodiment but also other fuel injection systems such as, for example, nozzle pumps

  and all electronically controlled injection systems

  valve; the control valve member and the surface area

  mant valve seat can be made in pairs or

  separately in ceramic material.

  According to other advantageous characteristics of the invention: * the electric control valve is mounted in the high pressure channel, * the closure member is in the form of a hollow cylindrical piston guided in sliding in a sleeve, one front face of which forms the valve seat, fixed, * a ceramic part fitted with the valve seat, * the valve sealing surface is made on

  the shutter member in the form of an annular flange

  laire, * the electrical control valve is a solenoid valve whose movable armature plate is connected to the shutter member, * the fuel injection device is produced in the form of an assembly comprising the pump, the pipe and nozzle.

Drawings.

  An exemplary embodiment of a fuel injection device according to the invention, applicable to internal combustion engines, is shown in the single

attached figure described below.

  The figure shows a simplified longitudinal section

  from the fuel injection device; this cup is

  carried out in the area of the electric control valve

  created in the high pressure channel.

  Description of the exemplary embodiment.

  The embodiment shown in FIG. 1 of the fuel injection device according to the invention for internal combustion engines is produced in the form of a pump-pipe-nozzle assembly. A high pressure fuel pump 1 comprises a pump piston 7 housed in the

  guide bore 3 of a pump body 5, following a movement

  axial ment which is driven by a non-detailed cam drive of the internal combustion engine in a reciprocating movement in the axial direction. The pump piston 7 delimits, in the bore 3, an active pump chamber 9

  into which a fuel supply line opens

  rant, controlled, not shown, and belonging to a low pressure fuel supply system; this pipe makes it possible to fill the working chamber 9 of the pump during the suction movement directed downwards from the piston of the pump 7 with fuel coming from a fuel supply tank. A high pressure channel 11 also starts from the working chamber 9 of the pump; the other end of this channel opens into a fuel injector 13, the injection orifices of which penetrate

  not shown, in the combustion chamber of the mo-

  internal combustion tor thus fed.

  To control the high pressure transfer to the high pressure fuel pump 1, a

  electrically controlled control valve 15 mounted in the case

  high pressure 11 connecting the working chamber 9 of the

injector pump 13.

  The electrically adjustable control valve 15 is produced in the form of a solenoid valve; an electrically actuated magnet 17 has a plate

  armature 19, sliding axially, which is connected to an or-

  shutter gane 21 in the form of a hollow cylindrical piston.

  This shutter member or valve member 21, which forms the actuating member of the electric control valve, is placed in the housing 5 of the pump, transverse to the high pressure channel 11; the actuating magnet 17 is clamped on the housing; this magnet projects radially forward. The valve member 21 is placed in a receiving bore 23 transverse to the high pressure channel 11 in the

  pump housing 5 in which a sleeve 25 is inserted

  mant valve seat at its peripheral surface.

  This sleeve forming the valve seat 25 comprises, at the level of the inlet orifices of the high pressure channel 11,

  in the receiving hole 23, a number of holes

  through passageways 27, radial, through which the flow of fuel leaving the working chamber of the pump 9 takes place via the high pressure channel 11, the sleeve forming

  valve seat 15 to the injector 13. The sleeve forms

  mant valve seat 25 shape, at its right end turn-

  born towards the adjustment magnet 17, a sealing surface 29 at its front surface. The valve seat sleeve 25 has a stepped inner diameter and the different diameter zones, starting from the opposite front surface, reach the level of the through holes 27. An inner wall zone, of smaller diameter, of the sleeve valve seat 25, is provided on the side

  of the sleeve 25 facing the actuating magnet 17.

  This sleeve, having an inner wall area of smaller diameter, thus forms a guide surface 31 for the closure member 21 which is guided with a part

  of its peripheral wall, so as to slide on the surface

  guide face 31, inside the sleeve 25. The piston-shaped closure member 21 has, at its end

  facing the actuating magnet 17, an annular flange

  milk 33 whose surface transient to the cylindrical peripheral wall of the valve member 21 forms a valve sealing surface 35 with which the valve member 21 cooperates to form a sealing section with the valve seat surface 29 on the sleeve 25. The movement of the opening stroke directed to the right, in the direction opposite to that of the actuating magnet 17, for the valve member 21 of the control valve 15, is limited by a cylindrical stroke stop body 37, used with the aid of a sealing flange surface 39 in the opening of the receiving hole 31 not turned towards the actuating magnet 17. In the stop body area of

  stroke 37, a return line 41 comes out of the re-drilling

  ception 23; this conduct leads in a manner not shown

  sensed in detail in the low pressure fuel supply system of the internal combustion engine.

  The member 21 of the control valve 15 is stressed

  cited in the direction of opening by a valve spring 43

  so that when the actuating magnet 17 is cut off from the neck

  rant, the member 21 is released by its sealing surface 35 from the valve seat 29 and that the fuel can pass from the high pressure channel through the sleeve 25 opening the sealing section between the surfaces 29 and 35 in the annular zone of the receiving bore surrounding the body forming a travel stop 37 then, beyond, by the return pipe

  41 to return to the low pressure system. For injec-

  ter, at the fuel injector 13, the actuating magnet 17 of the electric control valve 15 is supplied during the high pressure transfer stroke of the pump piston 7, so that the valve member 21 comes in

  waterproof support with its sealing surface 35 against the over-

  sealing face 29. The outlet section of the return pipe 41 is closed so that the fuel transferred at high pressure passes from the active chamber of the pump 9 through the high pressure channel 11 to reach

  the injector 13; at this level the fuel provides the injection.

  High pressure fuel injection is completed

  mine when the control magnet 19 is cut off again from the

  current, so that valve spring 43 pushes again

  calf the member 21 in the open position; then the high fuel pressure of the working chamber 9 of the pump and of the high pressure channel 11 expands again in the return line 41 so that the injection valve of

fuel 13 closes.

  To arrive in this case as long as possible actuation times for the electric control valve 15, to serve as a model for the injection profile and to achieve wear of the sealing seat

  as low as possible, the sleeve forming the seat

  pope 25 and the shutter member 21 of the control valve

  are made of ceramic material.

Claims (6)

R E V E N D I C A T IONS   1) Fuel injection device for a combustion engine   internal bustion fitted with a high pressure pump (1) to   fuel, the suction side of which is connected to a system   low pressure fuel supply valve, the   high pressure side is connected at least indirectly to an in-   fuel nozzle (13) opening into the fuel chamber   bustion of the internal combustion engine, the high pressure transfer being made by a high pressure channel (11) provided between the high pressure pump (1) and the fuel injector (13) using a valve electric control (15) which comprises a shutter member (21) electrically operated, sliding, having a sealing surface (35) by which this member cooperates with a valve seat (29), fixed, to form a sealing section, characterized in that the closure member (21) of the electric control valve (15) is ceramic.   2) Fuel injection device according to the claim   tion 1, characterized in that the electric control valve (15) is mounted in the channel high pressure (11).   3) Fuel injection device according to the claim   tion 1, characterized in that the closure member (21) is in the form of a hollow cylindrical piston guided in sliding in a sleeve (25), one of which   front face forms the stationary valve seat (29).   4) Fuel injection device according to the claim tion 1, characterized by   a ceramic part (25) provided with the valve seat (29).    ) Fuel injection device according to claim 1, characterized in that the valve sealing surface (35) is formed on the closure member (21) in the form of a flange an- ring (33).   6) Fuel injection device according to the claim   tion 1, characterized in that the electrical control valve (15) is a solenoid valve whose movable armature plate (19) is connected to the member shutter (21).   7) Fuel injection device according to the claim   tion 1, characterized in that the fuel injection device is produced in the form of an assembly comprising the pump, the pipe and the nozzle.