WO2020016513A1

WO2020016513A1 - Common-rail injection device

Info

Publication number: WO2020016513A1
Application number: PCT/FR2019/051770
Authority: WO
Inventors: Pierre-Yves GRIVEAU; Gilles DAUBORD
Original assignee: Duncha France
Priority date: 2018-07-16
Filing date: 2019-07-15
Publication date: 2020-01-23
Also published as: EP3824174B1; EP3824174A1; FR3083830B1; FR3083830A1; JP2021535322A

Abstract

The invention relates to an injection device comprising a common rail (2) extending in a longitudinal direction and defining a main chamber (4), the common rail (2) comprising: - an inlet port opening into the main chamber (4) and intended for being connected to a fuel supply pipe; - at least one injection well (5) extending along a first axis, said injection well (5) comprising a bottom (5a) and an injector interface area (5b) in which an injector (9) is to be mounted; - at least one transverse pipe (6) extending along a second axis and opening into the main chamber (4), on the one hand, and into the bottom (5a) of the injection well (5), on the other hand, so as to connect the main chamber (4) to said injection well (5), the first and second axes being secant; and - a nozzle (8) arranged in the bottom (5a) of the injection well (5) and reducing the fuel flow area between the pipe (6) and the injector interface area (5b) of the injection well (5).

Description

COMMON RAMP INJECTION DEVICE

Technical area

The present invention relates to a common rail injection device for an internal combustion engine.

Technological background

The prior art injection devices include a common rail having a main chamber, an inlet opening into the main chamber and intended to be connected to a fuel supply tube, a plurality of wells d 'injection which are distributed along the common rail and are each intended to receive an injector and a plurality of conduits each allowing to connect the main chamber to one of the injection wells.

It is known to the applicant that, in order to adapt the size of the injection device to its environment inside the vehicle, the injection wells are offset relative to the main chamber of the common rail. In other words, the geometric axis of the injection wells does not cross the main chamber of the common rail. Also, in order to be able to machine the conduit connecting the main chamber to the injection well, the machining is carried out transversely to the common rail through the main chamber of the common rail.

The injection devices are fitted with nozzles which are formed by reducing the fuel flow section so as to generate a pressure drop which makes it possible to absorb the pressure waves. Currently, there are at least two nozzle technologies. The first consists in fitting into the conduit connecting the main chamber of the common rail to the injection well a cylindrical element pierced axially. This fitting is particularly difficult to achieve, given the restricted accessibility of the conduits, for the aforementioned structures in which the injection wells are offset relative to the main chamber of the common rail.

According to a second technology, the conduit connecting the main chamber to the injection well has at the junction between said conduit and the injection well a lower section. For the aforementioned structures in which the injection wells are offset relative to the main chamber of the common rail, the machining of this smaller section requires the use of a drill of small diameter but of great length to reach 1 end of the conduit. However, the use of a small drill over such a long length makes it fragile with the risk of generating numerous manufacturing rejects and defects on the finished product.

summary

One of the aims of the present invention is therefore to provide an injection device comprising a common rail, which makes it possible to obviate the above drawbacks.

Another object of the invention is to provide such a device, the production of which is simple and inexpensive.

These aims, as well as others which will not appear below, are achieved by an injection device comprising a common rail extending in a longitudinal direction and defining a main chamber, the common rail comprising:

- an inlet opening into the main chamber and intended to be connected to a fuel supply tube,

- At least one injection well extending along a first axis, said injection well comprising a bottom and an injector interface zone in which an injector is intended to be mounted;

- At least one transverse conduit extending along a second axis and opening into the main chamber, on the one hand, and into the bottom of the injection well, on the other hand, so as to connect the main chamber to said well d injection, the first and second axes being intersecting; and

- a nozzle arranged in the bottom of the injection well and reducing the fuel passage section between the conduit and the injector interface zone of the injection well.

Thus, the sprinkler function being performed in a more easily accessible area, namely in the bottom of the injection well and not in the conduit, said function can be performed in a simpler and more reliable manner. According to other advantageous embodiments, such an injection device may have one or more of the following characteristics.

According to one embodiment, the nozzle is a cylindrical element which is fitted into the bottom of the injection well and which provides a space for the passage of fuel from the conduit to the injector interface zone. Such a cylindrical nozzle element can thus be fitted more easily into the bottom of the injection well than when it must be fitted into the duct connecting the main chamber to the bottom of the injection well.

According to one embodiment, the cylindrical element is force-fitted into the bottom of the injection well.

According to one embodiment, the bottom of the injection well has a diameter smaller than that of the injector interface zone. This facilitates the fitting of the cylindrical nozzle element in the bottom of the injection well.

According to one embodiment, the nozzle comprises at least a first channel and a second channel opening into one another and opening respectively opposite the injector interface zone and opposite the conduit, the first channel and the second channel having a diameter smaller than that of the conduit.

According to one embodiment, the nozzle is in abutment against the end of the injection well. This ensures precise axial positioning of the cylindrical element along the first axis.

According to one embodiment, the cylindrical element comprises polarization means making it possible to guarantee a positioning of the nozzle with respect to the bottom of the injection well in a relative position such that the second channel is directed opposite the conduit.

According to another embodiment, the cylindrical element provides a space for the passage of fuel between the conduit and a bottom area formed between the cylindrical element and one end of the injection well, the cylindrical element further comprising a channel crossing oriented along the first axis, opening on the one hand in said bottom area and, on the other hand in the injector interface area. According to one embodiment, the through channel oriented along the first axis has a diameter less than that of the conduit.

According to another embodiment, the cylindrical element provides a space for the passage of fuel between the conduit and an area of the bottom formed between the cylindrical element and one end of the injection well, the cylindrical element further comprising a flat providing a space between the cylindrical element and a wall of the bottom of the injection well allowing the passage of fuel from said bottom area to the injector interface area.

According to another embodiment, the first geometric axis crosses the pipe and the bottom of the injection well has a diameter smaller than that of the pipe and thus forms the nozzle. Drilling such a bottom of an injection well forming a nozzle requires drills that are shorter than those necessary for machining a nozzle in the axis of the conduit connecting the main chamber to the bottom of the injection well. The realization of such a nozzle is therefore simpler and generates less waste.

Brief description of the figures

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the accompanying drawings.

- Figure 1 is a perspective view of an injection device.

- Figure 2 is a vertical sectional view along the plane II-II of the injection device of Figure 1.

- Figure 3 is a sectional view along the plane lll-lll of Figure 2, showing an injection well.

- Figure 4 is a view similar to that of Figure 2 for an injection device according to a second embodiment.

- Figure 5 is a view similar to that of Figure 2 for an injection device according to a third embodiment. - Figure 6 is a view similar to that of Figure 2 for an injection device according to a fourth embodiment.

- Figure 7 is a view similar to that of Figure 2 for an injection device according to a fifth embodiment.

- Figure 8 is a perspective view of the nozzle of Figure 7.

- Figure 9 is a sectional view for an injection device according to a sixth embodiment.

Detailed description of embodiments

FIG. 1 represents an injection device designated as a whole by the reference 1. The injection device 1 comprises a common rail 2 which extends in a longitudinal direction. The common rail 2 is hollow and thus defines a main chamber 4 of tubular shape, illustrated in FIG. 2, extending in the longitudinal direction of the common rail 2. The common rail 2 is advantageously made in one piece, by example by a forging process.

The common rail 2 has an inlet 3 opening into the main chamber 4 of the common rail 2 and intended to be connected to a fuel supply tube, not shown.

Furthermore, as shown in FIG. 2, the common rail 2 comprises injection wells 5 which are each intended to receive an injector 9, partially illustrated in FIG. 2. Each of the injection wells 5 extends according to a geometric axis A. The injection wells 5 are offset relative to the main chamber 4. In other words, the geometric axis A of each injection well 5 does not pass through the main chamber 4.

Each injection well 5 has a bottom 5a and an injector interface zone 5b in which the injector is mounted 9. Advantageously, the bottom 5a like the injector interface zone 5b of each injection well 5 has a generally cylindrical shape.

The main chamber 4 of the common rail 2 is connected to each of the injection wells 5 by means of a conduit 6. Each conduit 6 has a cylindrical shape extending along an axis B which intersects the axis A. Each conduit 6 opens, on the one hand, into the main chamber 4, and, on the other hand, into the bottom 5a of one of the injection wells 5 and thus makes it possible to conduct the fuel from the main chamber 4 to said well d injection 5. In the embodiment shown in FIG. 2, the duct 6 opens laterally, that is to say at the level of the peripheral wall of the bottom 5a of the injection well 5.

Given the remote nature of the injection wells 5 relative to the main chamber 4, each conduit 6 is machined transverse to the longitudinal axis of the common rail 2 and by the side of the common rail 2 opposite the wells injection 5. Thus, to form each conduit 6, a through hole 7 is necessarily formed, in the common rail 2, opposite said conduit 6. The hole 7 extends coaxially to the geometric axis B of the conduit 6. The diameter of the conduit 6 is for example between 3 and 5 mm. In the embodiment shown, the axis B passes through the central axis of the main chamber 4. The bore 7 is intended to be closed in leaktight manner by means of a closure device, not shown.

Furthermore, the injection device 1 comprises a nozzle 8 formed in the bottom 5a of each of the injection wells 5. The nozzle 8 aims to reduce the cross-section of fuel passage between the conduit 6 and the injector interface zone 5b of the injection well 5. The nozzle 8 thus generates a pressure drop which makes it possible to damp the pressure waves.

In the first embodiment shown in Figures 2 and 3, the nozzle 8 is a cylindrical element which is force fitted into the bottom 5a of the injection well 5. The nozzle 8 is for example made of stainless steel. In order to allow such a fitting of the nozzle 8 into the bottom 5a of the injection well 5, the bottom 5a has a diameter smaller than that of the injector interface zone 5b.

Furthermore, the nozzle 8 comprises a frustoconical portion 20 which is positioned, along the axis A, opposite the duct 6 and which thus allows the fuel to penetrate into the bottom 5a of the injection well 5, and more particularly in a zone located between the end 11 of the injection well 5 and the nozzle 8. The nozzle 8 also has a through channel 10, which is oriented along the axis A of the injection well 5 and thus makes it possible to conduct fuel from the aforementioned bottom area 5a from the injection well 5 to the injector interface zone ôb. In the embodiment shown, the channel 10 passes through the nozzle 8 at its center.

The embodiments illustrated in FIGS. 4 to 7 differ from the embodiment described above in relation to FIGS. 2 and 3 only in the structure of the nozzle 8.

In the embodiment of Figure 4, the nozzle 8 has a through channel 10 which is oriented along the axis A of the injection well 5 and which passes through said nozzle 8. The nozzle 8 further comprises one or more channels 13 transverse which pass through the nozzle 8 radially. The channels 13 pass through the channel 10 and are advantageously perpendicular to said channel 10. The nozzle 8 is oriented in the bottom 5a of the injection well 5 so that one of the channels 13 opens facing the conduit 6. Thanks to the plurality of channels 13, there is a greater number of positions making it possible to ensure a relative positioning of the nozzle 8 with respect to the injection well 5 in which one of the channels 13 opens facing the conduit 6. In addition, according to an advantageous alternative embodiment, the nozzle 8 comprises polarizing means making it possible to guarantee a positioning of the nozzle 8 in a relative position such that one of the channels 13 is directed opposite the conduit 6. According to one embodiment, the polarization means are formed by a visual indication provided on the lower surface of the nozzle 8. According to another embodiment, in order to produce such polarization means, the bottom 5a of the well injection and the nozzle 8 each have a complementary geometric singularity making it possible to ensure mechanical coding.

In the embodiment of Figure 5, the nozzle 8 has a through channel 10 which is oriented along the axis A of the injection well 5 and which passes through said nozzle 8. The nozzle 8 further comprises a blind channel 15 which is oriented, in a radial orientation to the axis A, perpendicular to said channel 10. On the one hand, the channel 15 opens facing the conduit 6 and, on the other hand, it joins the channel 10 so as to allow passage fuel from the pipe 6 to the injector interface zone 5b of the injection well 5. According to an advantageous variant, the nozzle 8 comprises polarization means, as described above, making it possible to guarantee a positioning of the nozzle in a position such that the channel 15 is directed opposite the duct 6. In the embodiment of Figure 6, the nozzle 8 has a channel 16 which is oriented along the axis A. The channel 16 is blind, that is to say that it opens only opposite the area d injector interface 5b of the injection well 5a. The nozzle 8 further comprises another channel 15, also blind, which is oriented, in a radial orientation to the axis A, perpendicular to said channel 16. The channel 15 opens opposite the conduit 6 and joins the channel 16 so as to allow the passage of fuel from line 6 to the injector interface zone 5b of the injection well 5.

The nozzle 8 is also likely to include polarizing means. In addition, in this embodiment, the nozzle 8 abuts against the end 11 of the injection well 5, which ensures correct positioning of the nozzle 8, and more particularly of the channel 15, along of axis A.

In the embodiments of FIGS. 2 to 6, the channels 10, 13, 15, 16 have a diameter smaller than that of the conduit 6 in order to generate a pressure drop. For example, their diameter is between 0.75 to 1.5 mm. In the embodiment illustrated in Figures 7 and 8, the nozzle 8 has no channel but has a flat 8c extending over the entire length of said nozzle 8. As shown in Figure 7, the nozzle 8 is fitted in the bottom 5a of the injection well 5 so as to preserve a space 18 between the duct 6 and a zone situated between the end 11 of the injection well 5 and the nozzle 8. The flat 8c thus makes it possible to provide space between the nozzle 8 and the cylindrical wall of the bottom 5a of the injection well 5 a space 19 allowing the passage of the fuel towards the injector interface zone 5b.

According to a sixth embodiment shown in FIG. 9, the axis A of the injection well 5 passes through the conduit 6 so that the bottom 5a of the injection well 5 opens into the conduit 6. The bottom 5a of the well 5 which connects the injector interface zone 5b with the conduit 6 has a diameter smaller than that of the conduit 6 and that of the injector interface zone 5b. Thus, it is here the bottom 5a of the injection well 5a which forms the nozzle 8 generating a pressure drop allowing the pressure waves to be damped. The diameter of the bottom 5a of the injection well 5 is for example between 0.75 to 1.5 mm. Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these are within the scope of the invention.

The use of the verb "behave", "understand" or "include" and its conjugate forms do not exclude the presence of other elements or steps than those set out in a claim.

In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

1. Injection device (1) comprising a common rail (2) extending in a longitudinal direction and defining a main chamber (4), the common rail (2) comprising:

- an inlet (3) opening into the main chamber (4) and intended to be connected to a fuel supply tube,

- at least one injection well (5) extending along a first axis, said injection well (5) comprising a bottom (5a) and an injector interface zone (5b) in which is intended to be mounted an injector (9);

- at least one transverse conduit (6) extending along a second axis and opening into the main chamber (4), on the one hand, and into the bottom (5a) of the injection well (5), on the other part, so as to connect the main chamber (4) to said injection well (5), the first and second axes being intersecting; and

- a nozzle (8) arranged in the bottom (5a) of the injection well (5) and reducing the cross-section of the fuel passage between the conduit (6) and the injector interface zone (5b) of the injection well (5).

2. Device (1) according to claim 1, in which the nozzle (8) is a cylindrical element which is fitted in the bottom (5a) of the injection well (5) and which provides a space (10, 13, 15 , 16, 18, 19) for passing the fuel from the conduit (6) to the injector interface zone (5b).

3. Device (1) according to claim 2, wherein the bottom (5a) of the injection well (5) has a diameter less than that of the injector interface area (5b).

4. Device (1) according to claim 2 or 3, wherein the nozzle (8) comprises at least a first channel (10, 16) and a second channel (13, 15) opening into one another and opening respectively opposite the injector interface zone (5b) and opposite the conduit (6), the first channel and the second channel having a diameter less than that of the conduit (6).

5. Device (1) according to claim 4, wherein the nozzle (8) abuts against the end (11) of the injection well (5).

6. Device (1) according to claim 2 or 3, wherein the cylindrical element provides a fuel passage space between the conduit (6) and a bottom area (5a) formed between the cylindrical element and one end ( 11) of the injection well (5), the cylindrical element further comprising a through channel (10) oriented along the first axis, opening on the one hand into said bottom zone (5a) and, on the other hand into the injector interface zone (5b).

7. Device (1) according to claim 2 or 3, wherein the cylindrical element provides a fuel passage space between the conduit (6) and a bottom area (5a) formed between the cylindrical element and one end ( 11) of the injection well (5), the cylindrical element further comprising a flat (8c) forming between a cylindrical element and a bottom wall (5a) of the injection well (5) a space (19) authorizing the passage of fuel from said bottom zone (5a) to the injector interface zone (5b).

8. Device according to claim 1, in which the first axis passes through the duct (6) and in which the bottom (5a) of the injection well (5) has a diameter smaller than that of the duct (6) and thus forms the nozzle (8).