FR2768185A1 - FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Installation taking fuel from a low pressure chamber (5) to supply an injector (7) via a high pressure line (3) using a high pressure pump (1) and a hydraulic reduction system ( 13). This is provided between the pump (1) and the injector (7). It comprises a stepped piston (19), the front surfaces of which each define a pressure chamber (23, 27) as well as a supply channel equipped with a pressure valve (45) for filling the chamber (27). The chamber (27) is filled with the aid of a channel starting from the first pressure chamber (23).

Description

STATE OF THE ART The present invention relates to an installation

  injection systems for internal combustion engines

  dull including a high pressure pump taking the fuel

  rant of a low pressure chamber (5) for supplying an injector via a high pressure line and a hydraulic reduction system mounted between the high pressure pump and the injector and comprising a piston sliding in a bore, the front surfaces of the piston delimiting each a pressure chamber, the first largest front surface defining a first pressure chamber connected to the high pressure line on the pump side and the second, opposite, smaller, front surface delimiting

  a second pressure chamber connected to the part of the con-

  high pressure line going to the injector, as well as a supply channel equipped with a pressure valve to fill

  fuel the second pressure chamber.

  In such a fuel injection installation

  rant known according to document DE 41 18 237 A1, the fuel is transferred from a low pressure chamber by a high pressure line to the injector via a high pressure pump. To increase the pressure at the fuel injector, a hydraulic reduction system is provided between the high pressure pump and

  the fuel injector. This reduction system

  tion hydraulic comprises a stepped piston sliding in a bore and the front surfaces each delimit a pressure chamber; the first front surface, the largest delimits a first pressure chamber on the side

  of the pump and the second, smaller front surface defines a pressure chamber on the injection side. The-

  hydraulic pressure multiplication at the gear reduction system thus depends on the ratio of the front surfaces of the pump piston delimiting the 35 pressure chambers; the stepped piston is actuated by the high pressure fuel supply arriving on

  the largest front surface of the piston.

  The pressure chamber is filled on the injection side, at the level of the small front surface of the stepped piston of the reduction system.

  through a valve device from the car circuit

  of the injection system. The return movement of the stepped piston is also ensured hydraulically by the fuel circuit and by a corresponding valve device fitted to a supply line in the

reminder chamber.

  The known fuel injection installation for an internal combustion engine has the drawback of requiring a large number of regulating valves and

  to have a complicated construction. In addition, the instal-

  known fuel injection lation is very cumbersome because of the complicated valve control and this space is generally not available at the level of the engines with

current internal combustion.

  Another drawback of the demul-

  multiplication of the known fuel injection system is the large volume to be pumped into the return chamber which considerably deteriorates the efficiency of the reduction system. Advantages of the invention The aim of the present invention is to develop

  a fuel injection system remedying the

  the known solutions. To this end, the invention

  concerns an installation of the type defined above, character-

  that the feed channel opening into the second pressure chamber comes from the first chamber

pressure.

  The fuel injection installation according to the invention offers the advantage over the prior art of being able to increase the injection pressure at the level of

  injector and improve hydraulic efficiency, that is

  tell the relationship between injection energy and work

  supplied to the entire injection system, without

  Tically increase the size compared to injection systems without reduction system. In addition, the fuel injection installation according to the invention has, vis-à-vis known injection installations equipped with a reduction gear, the advantage of requiring the use of construction means and much lower mounting due to simpler construction. This is made possible in particular because the filling of the second pressure chamber, that is to say that of the side of the injector, is done from the high pressure zone between the high pressure pump and the gear reduction system. This removes an additional supply line from the area

low pressure.

  It is particularly advantageous that the filling of the pressure chamber on the injection side takes place via a filling valve provided as a pressure valve in the connecting line or the

  supply line between the high pressure line and the pressure chamber parallel to the stepped piston. The supply line which fills the pressure chamber on the side of the injector may be a bypass line.

  This embodiment as a bypass pipe offers the advantage of making it possible to produce the stepped piston in two parts, which simplifies the manufacture of the installation of

  reduction. Such a bypass line of pref-

  there is no difference in parallel to the stepped piston

  cultured to function and can also be produced without

strict tolerance.

  Another possibility for feeding

  tation is to realize this directly as a drilling

  passing through the stepped piston which has the advantage of reducing the dimensions of the reduction gear.

  This allows retrofitting installations in existing fuel lines with known injection systems such as, for example, dis-tributary pumps, pump-pipe-nozzle systems or common rail systems. The filling valve mounted in the supply line is then made as a

  pressure preferably as a non-return valve whose pressure

  opening tension is adjusted by the spring applied to the

  Pope. The stepped piston of the reduction gear has a sliding surface as long as possible in the guide hole so that advantageously very little fuel can pass between the pressure chambers.

  sion by the clearance between the stepped piston and its guide hole

  dage; thus, the reduction gear does not present

  that very little leakage loss. The gear ratio-

  tion at the level of the stepped piston preferably corresponds to the ratio between the large front surface and the small surface

  frontal is from 1 to 3 and in particular the ratios of

  multiplication between 1.5 and 2.2 are particularly

  appropriate because then the hydraulic efficiency increases consi-

  derailment without requiring a significant increase in

  high pressure pump flow.

  From an energy perspective, this increase in efficiency has more significance than just

  pressure increase at the injector because the re-

  duction of drive energy also decreases the

  thermal load of the pump and thus the tendency to wear.

  This allows for more regular games between the pis-

  your or the distributor shafts and their sockets so

  that this smaller leakage increases the yield all the more.

  Another advantage is linked to the integration of the wire-

  be rod in the supply channel of the pressure chamber

  injection side because then the dead volume in the

  high pressure area on the injection side is again di-

minuted.

  The volume driven back by the annular front surface

  the piston of the piston at the level of the spring chamber of the stepped piston is advantageously discharged preferably in counter pressure in the low pressure circuit so

  that the hydraulic losses of the reduction system

cation are minimized.

  To guarantee operation, a throttle point is also provided in the supply line of the pressure chamber on the injection side, this throttle point being large enough to allow a

  refilling by the return movement of the piston

  ge; the throttling point is small enough that at the pressure reduction stroke carried out by the stepped piston, this creates a pressure difference quickly closing the check valve. This separate throttling point can be eliminated if upstream of the non-return valve, a rod filter is fitted, the intervals of which are

  as they provide the required throttling.

  The return of the stepped piston of the reduction system advantageously takes place by a return spring so that this movement does not require any additional hydraulic return force. This also avoids any control line and additional control valve, which further simplifies the construction of the installation.

of reduction.

  Another advantageous embodiment of

  the injection system according to the invention consists of my-

  ter the staged piston in a guide sleeve housed therein

  even in a tubular sleeve. The pre-

  feel longitudinal slots through which a connecting element preferably a clamp and acting radially on the shoulder of the stepped piston. The piston return spring

  stepped acts radially on the outside of the mistletoe

  dage, this spring being guided in an annular volume between

  the guide sleeve and the inner wall of the tubular sleeve

  laire. This arrangement of the spring offers a large winding diameter for the return spring, that is to say a large spring stroke. In addition, the parts of the reduction system can thus be produced

  in a simple way like pieces having a symmetry of ro-

  This reduces the manufacturing cost and the space required. The bypass channel is advantageously integrated in the guide jacket and the pressure valve opening towards the pressure chamber on the

  the injector is preceded by a choke point.

  The bypass channel is a simple longitudinal drilling in the guide jacket; it opens with an extension of the guide hole receiving the stepped piston in

  the guide jacket, in the respective pressure chambers. The stepped piston can be made in one piece as in the embodiment shown; for reasons of simplicity of manufacture, it is more advantageous to produce the stepped piston in two parts which is possible

  ble analogously, without modification for the construction shown. Another advantage of the fuel injection installation according to the invention lies in the maximum approximation of the reduction gear to the injector so that the area in which very high fuel pressures prevail is limited to a length very reduced line of conduct in which such high pressures are effectively required. This reduces the dead volume of the high pressure injection area and thus the loss of work

  hydraulic. Moreover, the area of the fuel line on the pump side is at a reduced pressure so that the components in this area are less stressed and thus they can be dimensioned more weakly for the same long service life.

  The facilities for reducing the differences

  fuel injectors can be connected and the connection with the high pressure fuel pump can be

do by common conduct.

  According to other advantageous features of the invention: * the pressure valve of the supply channel is connected

  in parallel on the stepped piston of the

hydraulic multiplication,

  * the feed channel is a contour bypass channel

  the stepped piston, * the feed channel is mounted in parallel to the stepped piston, * the feed channel is formed by a first transverse bore starting from the first pressure chamber and by a second transverse bore starting from the second

  pressure chamber as well as a longitudinal drilling

  linking these two transverse holes, this longitudi-

  nal preferably being of axis parallel to the bore receiving the stepped piston, * the supply channel is formed by a through bore in the stepped piston and the pressure valve which closes the

  supply channel is housed inside the piston

  ge, * the pressure valve consists of a shut-off valve opening towards the second pressure chamber and whose opening pressure is lower than the residual pressure in the high pressure line, * the staged piston is sliding sliding guide

  in drilling the body of a reduction system

  cation, * the gear ratio of the stepped piston corresponds to the ratio of the largest front surface and the smallest front surface of the piston, and to a value included

  between 1 and 3, preferably between 1.5 and 2.2.

  * a fuel filter preferably a rod filter housed

in the feed channel.

  * an annular flange provided at the junction of the sections of the stepped piston, this flange forming by its annular front surface facing the piston part of larger diameter Dl, a bearing surface which cooperates with a

  shoulder of the bore and the other front surface of which

  ring facing the side of the smaller diameter piston D2, delimits a spring chamber in the bore,

  * a return spring which surrounds the stepped piston preferably

  coaxially the clamp is clamped in the spring chamber and this spring bears against a fixed support to urge the

  piston stepped at its annular front surface if-

  killed on the side of the spring chamber, in the direction of

  the shoulder of the hole, and depending on the pressure

  in the high pressure line, the front surfaces of the piston and the opening pressure of the pressure valve in the supply channel, it pushes the staged piston against its stop on the side of the pump between injections,

  On the fixed bearing surface of the spring is provided on a

chon housed in the hole,

  * at least one discharge line, connects the resistor chamber

  goes out to the low-pressure chamber, * the stepped piston is guided in a sliding way in a guide hole in a guide jacket, itself housed in a tubular sleeve, * an annular volume is formed between the guide jacket

  and the inner wall of the tubular sleeve, this volume re-

  cevant a return spring, for the stepped piston, * the return spring is supported by its surface located on the side of the small front surface of the stepped piston against a fixed stop and by its opposite front surface, turned towards the large front surface of the piston, the spring acts on a connecting element and the latter passes radially through the guide jacket through the longitudinal slots and applies it against a shoulder of the stepped piston, ò the connecting element is a U-shaped clamp, * the supply channel filling the pressure chamber

  on the side of the injector is made in the form of a

  longitudinal bore in the guide sleeve, radially outside the guide bore and which opens at the level

  front surfaces of the guide jacket by ex-

  diameter tensions of the guide hole in the cham-

pressure bres,

  * the guide sleeve is tightened axially against a shoulder

  Lement of the tubular sleeve by a nozzle screwed into the tubular sleeve, * the pressure chamber on the pump side is provided in the part of the tubular sleeve adjacent to the guide liner and the pressure chamber on the injection side is located inside the nozzle, * a shut-off valve opening towards the pressure chamber on the injection side is provided in the longitudinal bore, and a choke point is upstream of

  this shutoff valve in the direction of flow.

  * the hydraulic reduction system is planned for

close to the injector.

  Drawings The present invention will be described below with the aid of three exemplary embodiments of a fuel injection installation for internal combustion engines, represented in the attached drawings in which: - Figure 1 shows a first example of realization of a

  fuel injection system in which the

  pressure chamber supply line from the

  the injector is produced by a through hole in the pis-

  tone stepped of the reduction gear, - Figures 2A and 2B show two views of a second embodiment, the supply line of the pressure chamber on the side of the injector being formed by a parallel bypass channel with the stepped piston,

  - Figures 3A and 3B show a third example of a

  setting with two positions for the stepped piston, the con-

  feed line being produced in the guide jacket receiving the stepped piston, this jacket itself being placed in a tubular sleeve and, - Figure 4 is a detail view of the clamp connecting the return spring and the stepped piston of the third example

of achievement.

  Description of the exemplary embodiments

  The fuel injection installation according to FIG. 1 for internal combustion engines comprises a

  high pressure pump 1 which supplies fuel by means of a

  high pressure line 3 from a low pressure chamber preferably a fuel tank to an injector 7. To control the supply of high pressure fuel

  of the injector 7, it is provided in the exemplary embodiments

  tion described, a control valve 9, preferably an electromagnetic valve in the bypass line 11 from the high pressure line 3; this bypass line returns as a return line in the low pressure chamber 5. Downstream of the control valve 9 there is provided a non-return valve 12 opening in the direction of the low pressure chamber 5; the remaining residual pressure

  in bypass line 11 and high pressure line

  sion 3 is adjusted by this non-return valve.

  The control valve 9 is switched so that the fuel supplied by the high pressure pump 1 feeds the injector 7 when the control valve 9 is closed

  but that if the control valve 9 is open, the fuel

  rant returns to bypass line 11 in the cham-

  bre low pressure 5 (short circuit), non-return valve

  12 fitted to the bypass line 11 now holding a

  residual pressure in the system.

  To increase the injection pressure at the injector 7, the high pressure line 3 is equipped with a hydraulic reduction system 13 between

  the high pressure pump 1 and the injector 7. This installation

  tion of hydraulic reduction 13 comprises a stepped piston 19 guided axially in a guide bore 15 of a body 17; with its axial front surfaces, the stepped piston delimits each time a pressure chamber in the bore 15 of the body 17 of the reduction gear 13. The first front surface 21, the largest of the stepped piston 19 delimits a first pressure chamber 23 also connected to the part of the high pressure pipe 3

  going to the high pressure pump 1. The second front surface

  tale 25 of the stepped piston 19, the smallest, delimits a

  second pressure chamber 25 in the body 17 of the reduction gear 13; this second pressure chamber is opposite to the first pressure chamber 23 and it is connected to a second part of the high pressure pipe 3 going to the injector 7. The stepped piston 19 in a single piece of the first embodiment presented at passage of the section between the large diameter Dl and the small diameter D2, an annular flange 29 projecting from the large diameter Dl. With its annular front surface 31 on the side

  opposite that of the large diameter of the stepped piston, the adhesive

  annular rette 29 delimits towards the second cham-

  pressure bre 27, a spring chamber 33 of which the other

  end is delimited by a sleeve 35 pressed in the per-

  lashing 15 of the body 17 from the other pressure chamber l 27. The internal surface of the sleeve 35 which axially guides the part of the stepped piston 19 of small diameter D2, defines the second pressure chamber 27 on the injection side . The annular front surface delimiting the spring chamber 33 of the sleeve 35 also serves as a support for the return spring

  37 clamped in the spring chamber 33; this spring acts

  be the annular front surface 31 of the annular flange

  area 29 of the stepped piston 19 and maintains it with the annular flange 29 in abutment against a shoulder 39 of the

  hole 15 made in the body 17. Preferably two connectors

  discharge lines 41 start from the spring chamber 33 and open into the low-pressure chamber 5. To fill the fuel in the second pressure chamber 27

  on the injection side, the stepped piston 19 includes a

  through hole 43 going from the first pressure chamber 23 to the second pressure chamber 27. This through hole 43 comprises a non-return valve 45 serving as a filling control valve and the closure member 49 of which can be lifted from the seat valve 51 against force

  obturation exerted by a valve spring 47 directly

  tion of the second pressure chamber 27. In addition, a fuel filter 57 in the form of a rod filter is placed in the region of the through bore 43 of the stepped piston 19 on the side of the first pressure chamber 23; the intervals of this

  filter are such that in addition to the fuel filtering effect

  this filter also performs the throttling function

  required for the reduction valve 13.

  The stepped piston reduction ratio 19

  defined by the diameters Dl, D2 of the first fron-

  tale 21 and the second front surface 25 is in a range from 1 to 3 and it preferably has a value included

between 1.5 and 2.2.

  The fuel injection installation according to the invention operates as follows: Before the start of the high pressure injection

  by the injector 7, the second pressure chamber 27 is replaced

  bends fuel through the supply line formed by the through bore 43 of the stepped piston 19. This filling of the pressure chamber 27 continues until between the pressure chambers 23, 27 connected, there is a pressure balance so that the non-return valve 45 closes the supply line. The injection at the injector 7 begins when the control valve 9 closes the bypass line 11 and the high pressure pump 1 delivers

  in the high pressure line to the injector 7. In con-

  sequence, the high fuel pressure develops first in the first pressure chamber 23 on the stepped piston 19 of the hydraulic reduction system

  13; this pressure then moves the stepped piston 19 di-

  rection of the second smaller pressure chamber 27. Due to the difference in the annular front surfaces 21, of the stepped piston 19, this results in an increase in the pressure prevailing in the second pressure chamber 27 relative to the fuel pressure established by the pump.

  high pressure. This increase in fuel pressure

  rant is transmitted by the second part of the high pressure line 3 to the injector 7 and from there to the injection orifices to inject into the combustion chamber of the engine thus supplied. The fuel which is in the spring chamber 33 is discharged without significant opposing pressure, through the discharge lines 41 and this practically does not reduce the efficiency of the reduction gear 13. The non-return valve 45 is maintained

  closed by the force resulting from the excess of the force

  generated by the pressure in the pressure chamber 27 and the

  force of valve spring 47 relative to force generated

  drawn by the pressure in the pressure chamber 21. The

  non-return pope 45 remains closed during the race

active plunger 19.

  The injection of high pressure fuel by the injector 7 ends when the control valve 9 of the bypass line 11 opens again so that the high pressure line 3 connected to the lower chamber

  pressure 5 and the high fuel pressure 3 in the con-

  high pressure nozzle 3 and thus in the demul-

  multiplication 13 expands to residual pressure

  adjustable in the low pressure chamber 5. This pressure

  sidual is adjusted by the non-return valve 12 of the bypass line 11, in the high pressure line 3 by the opening pressure of the non-return valve 45; thus, the second pressure chamber 27 is refilled with fuel during the return movement of the stepped piston 19 from the first pressure chamber 23 through the through bore 43. The return movement of the stage piston

  19 is mainly provided by the force of the return spring

  pel 37 which pushes back the staged piston 19 to put its adhesive

  annular rette 29 bearing against the shoulder 39 of the bore of the body, putting the piston in its rest position. The fuel coming from the first pressure chamber 23 is filtered in its passage to the second pressure chamber

  27 by the fuel filter 57 in the form of a rod filter.

  The second example of the installation

  fuel injection lation according to the invention for internal combustion engines differs from the first example

  of realization only by the installation of reduction

  tion 13 of the high-pressure pipe 3 so that FIGS. 2 slimitate to the presentation of this reduction gear 13. FIG. 2A shows the second exemplary embodiment of the reduction gear 13 in

  sectional view and FIG. 2B shows the installation of demul-

  multiplication 13 of FIG. 2A turned 90.

  The reduction gear 13 of the second

  example of implementation differs from the installation of

  multiplication 13 of the first embodiment of the fi

  Figure 1 by the arrangement of the supply line from the first pressure chamber 23 on the pump side to the second pressure chamber 27 on the injector side for a

  stepped piston 19 now made as a piston in two parts

  ties. This supply or filling channel for the second pressure chamber 27 of the second embodiment is in the form of a bypass pipe produced in parallel to the

  stepped piston 19 in the body 17 of the demulding installation

  hydraulic multiplication 13. The bypass pipe is formed by a first transverse bore 59 starting from the first pressure chamber 23 as well as a second transverse bore 61 starting from the second pressure chamber 27; these two holes are connected by a longitudinal bore 63 preferably passing parallel to the axis of the stepped piston 19. In a similar manner to the through bore 43 of the stepped piston

  ge 19 of the first example of embodiment, this longitu-

  dinal 63 includes a non-return valve 45 and a filter

fuel 57.

  The hydraulic reduction system 13 shown in FIGS. 2A, 2B operates in the same way as the reduction system 13 of the fuel injection installation according to the invention shown in FIG. 1. The reduction ratio at the level the reduction gear 13 is also defined by the ratio of the front surfaces 21, 25 of the stepped piston 19; this ratio is also within a range of 1 to 3

  and preferably a range of 1.5 to 2.2.

  In the case of the third embodiment shown in FIGS. 3A, 3B, the stepped piston 19 is guided in sliding in a guide jacket 67 housed in a guide hole 65; this jacket is itself mounted in a tubular sleeve 69. The stepped piston 19 defines with its larger front surface 21 the first pressure chamber 23 on the side of the pump; with its small surface

  25, the piston delimits the second pressure chamber

  sion 27 on the injector side. The first press room

  sion 23 is thus located in an enlarged diameter segment of

  corresponding way of the guide hole 65 and partial-

  ment in the adjacent area of the tubular sleeve 69; the se-

  this pressure chamber 27 is provided in a through hole in the nozzle 73 screwed into the tubular sleeve 69 on the side of the injector; this nozzle thus fixes the jacket of

  guide 67 axially against a shoulder 75 of the sleeve tu-

  bular 69. At the end of the nozzle 73 opposite the tubular sleeve 69, according to the exemplary embodiment, an injector support body 77 has been screwed for the injector 7; headquarters

  sealing is done by a conical packing 79 tight in-

  be the injector support body 77 and the nozzle 73

  (axial tightening); this trim piece has a per-

axial through hole.

* In addition, between the peripheral wall of the che-

  guide layout 67 and the inner wall of the tubular sleeve

  area 69, there remains an annular volume 71 receiving in this third embodiment, the return spring 37 of the stepped piston 19. The return spring 37 bears against the front surface of the nozzle 73, in a fixed manner and by its other end it urges the stepped piston 19 by means of a clamp 81, acting in the direction

of the pressure chamber 23.

  This U-shaped clamp 81, shown in ma-

  nière separate in Figure 4, has a slot 83 whose dimension corresponds to the small diameter of the stepped piston 19 or a receiving groove provided at the junction of the sections

  of the stepped piston 19. The clamp 83 crosses radially the sleeve

  guide layout 67 at longitudinal slots not

  presented and leans against the drop in diameter of the

stepped piston 19.

  The stroke of the stepped piston 19 towards the pressure chamber 23 on the pump side is delimited by an annular shoulder 85 at the periphery of the guide jacket 67; the return spring 37 pushes the stepped piston 19 into this rest position. The active stroke of the stepped piston 19 towards the pressure chamber 27 on the side of the injector is limited by a shoulder 91 of the guide bore 65 against which the stepped piston 19 is supported with the clamp 81 (FIG. 3A). filling of the second pressure chamber 27 is done by a bypass or supply line

  starting from the first pressure chamber 23; this con-

  pick is formed by a longitudinal axial bore 87 in the guide jacket 67. The fuel is then passed, depending on the position of the stepped piston, directly into the

  pressure chambers 23, 27 delimited by the front surfaces

  guide sleeve 67 or by the residual play in

  be the stepped piston 19 and the walls of the through holes

  tubular sleeve 69 or nozzle 73. The long hole

  tudinal 87 has a non-return valve 45 opening

  direction of the pressure chamber 27 on the injection side; a throttling point 89 is provided upstream of the non-return valve 45. The operation of the third embodiment is similar to that of the previous examples; the fi-

  gure 3A shows the position of the stepped piston 19 during the active stroke when it reaches the end of stroke position. Figure 3B shows the stepped piston 19 just before it reaches its rest position; the new filling of the pressure chamber 27 is then done by the

  supply channel following the clearance of the stepped piston 19 in the sleeve 69, the longitudinal bore 87 and the non-return valve 45 before the stepped piston 19 reaches its rest position.

Claims (17)

R E V E N D I C A T ION S   1) Fuel injection installation for internal combustion engines comprising a high pressure pump (1) taking fuel from a low pressure chamber (5) to supply an injector (7) via a high pressure line (3) and a hydraulic reduction system (13) mounted between the high pressure pump (1) and the injector (7) and comprising a piston (19) sliding in a bore (15),   the frontal surfaces of the piston each delimiting a cham-   pressure bre, the first front surface (21) most   large delimiting a first pressure chamber (23)   linked to the high pressure line (3) on the pump side and   the second, opposite, smaller front surface (25), delimiting   mitting a second pressure chamber (27) connected to the   tie of the high pressure line (3) going to the injector, as well as a supply channel equipped with a pressure valve to fill the second pressure chamber (27) with fuel, characterized in that the channel d The feed opening into the second pressure chamber (27) comes from the first pressure chamber (23).   ) Fuel injection system according to the claim   tion 1, characterized in that the pressure valve of the supply channel is connected in parallel to the stepped piston (19) of the installation hydraulic reduction (13).   3) Fuel injection installation according to the claim tion 1, characterized in that   the supply channel is a contour bypass channel the stepped piston (19).   4) Fuel injection installation according to the claim tion 3, characterized in that   the supply channel is mounted in parallel with the piston ge (19).   5) Fuel injection installation according to claim 4, characterized in that the supply channel is formed by a first transverse bore (59) starting from the first pressure chamber (23) and by a second transverse bore (61) starting from   second pressure chamber (27) and a long hole   dinal (63) connecting these two transverse holes, this longitudinal hole preferably having an axis parallel to the hole   (15) receiving the stepped piston (19).   ) Fuel injection system according to the claim   tion 1, characterized in that the supply channel is formed by a through hole (43) in the stepped piston (19) and the pressure valve which   closes the feed channel is housed inside the pis- your tier (19).   7) Fuel injection installation according to the claim   tion 1, characterized in that the pressure valve consists of a shut-off valve (45) opening towards the second pressure chamber (27) and the opening pressure of which is lower than the   residual pressure in the high pressure line (3).   8) Fuel injection installation according to the claim tion 1, characterized in that   the stepped piston (19) is guided in sliding manner   che in the bore (15) of the body (17) of an installation reduction (13).   9) Fuel injection installation according to the claim tion 1, characterized in that   the reduction ratio of the stepped piston (19) corresponds to   pond to the ratio of the largest front surface (21) and the smallest front surface (25) of the piston, and to a value   between 1 and 3, preferably between 1.5 and 2.2.    ) Fuel injection system as claimed   cation 1, characterized by a fuel filter (57) preferably a rod filter housed in the feed channel.   11) Fuel injection system as claimed cation 1, characterized by   an annular collar (29) provided at the junction of the sec-   tions of the stepped piston (19), this flange forming by its annular front surface turned towards the piston part of larger diameter Dl, a bearing surface which cooperates   with a shoulder (39) of the bore (15) and the other of which   annular front face (31) facing the side of the smaller diameter piston D2, delimits a spring chamber (33) in the hole (15).   12) Fuel injection installation as claimed   cation 11, characterized in that a return spring (37) which surrounds the stepped piston (19) preferably coaxially is clamped in the spring chamber (33) and this spring bears against a fixed support to urge the stepped piston (19) at its annular front surface (31) located on the side of the spring chamber, in the direction of the shoulder (39) of the bore, and as a function of the residual pressure in the high pipe pressure (3), the front surfaces of the piston (21, 25) and of the opening pressure of the pressure valve in the channel   feed, it pushes the stepped piston (19) against its   tee (39) on the pump side between injections.   13) Fuel injection system as claimed   cation 11, characterized in that the fixed bearing surface of the spring is provided on a sleeve (35) housed in the bore (15).   14) Fuel injection system as claimed   cation 11, characterized in that at least one discharge line (41) connects the spring chamber (33) to the low pressure chamber (5)    ) Fuel injection system as claimed   cation 1, characterized in that the stepped piston (19) is slidably guided in a   guide hole (65) of a guide jacket (67) itself housed in a tubular sleeve (69).   16) Fuel injection installation according to claim 15,   characterized in that an annular volume (71) is formed between the guide jacket   dage (67) and the inner wall of the tubular sleeve (69), this volume receiving a return spring (37) for the stepped piston (19).   17) Fuel injection installation as claimed   cation 16, characterized in that the return spring (37) is supported by its surface located on the side of the small front surface (25) of the stepped piston (19) against a fixed stop and by its opposite front surface, facing the large front surface (21) of the piston, the spring acts on a connecting element and the latter passes through   radially the guide jacket (67) through the slots   and press it against a shoulder of the stepped piston (19). 18) Fuel injection installation according to claim 17, characterized in that the connecting element is a clamp (80) in the shape of a U.   19) Fuel injection system as claimed   cation 15, characterized in that the supply channel filling the pressure chamber (27) on the side of the injector is produced in the form of a longitudinal bore (87) in the guide jacket (67), radially at outside of the guide hole (65) and which opens at the front surfaces of the guide jacket (67) by extensions of the bore diameter   guide (65) in the pressure chambers (23, 27).    ) Fuel injection system as claimed   cation 15, characterized in that the guide jacket (67) is axially clamped against a shoulder (75) of the tubular sleeve (69) by a nozzle (73)   screwed into the tubular sleeve (69).   21) Fuel injection system as claimed   cation 20, characterized in that the pressure chamber (23) on the pump side is provided   in the part of the tubular sleeve (69) adjacent to the sleeve   guide layout (67) and the pressure chamber (27) on the side   of the injection is inside the nozzle (73).   22) Fuel injection system as claimed   cation 19, characterized by a shut-off valve (45) opening towards the chamber   Pressure side (27) on the injection side is provided in the longitudinal bore (87), and a throttle point (89) is upstream of this shut-off valve in the direction of flow.   23) Fuel injection system as claimed cation 1, characterized in that   the hydraulic reduction system (13) is provided near the injector (7).