FR3087140A1 - PROCESS FOR TREATING THE BORING EDGE OF THE CONNECTING END PIECES OF A COMMON RAMP AND COMMON RAMP THUS PRODUCED - Google Patents

Abstract

Method for treating the edge of the radial holes (21) of the nozzles (2) for connecting the injectors with the axial chamber (11) of a common rail (100) of an internal combustion engine injection system, method according to which is deburred the outlet of the radial bores (21) in the chamber (11) of the common rail. A junction ring (3) is produced in the form of a surface of revolution (3S) along the axis (ZZ) of the bore (21) leveling the edge (22) of the opening of the radial bores (21) in the axial chamber ( 11) overflowing on the surface (11S) of the axial chamber (11) and on that (21 S) of the radial bores (21).

Description

Field of the invention

The subject of the present invention is a method of manufacturing a common rail of an injection system consisting in producing a rail body by hot forging and drilling the chamber along the main axis, and making radial holes for connection injectors, a process by which the outlet of the bores is deburred in the chamber of the common rail.

State of the art

The alternations of very high fuel pressures subject the common rail of the injection system to significant fatigue generating risks of rupture at the junction of the radial bores and the chamber of the rail.

It is known to deburr the outlet of the radial bores of the common rails so as to reduce the risk of failure.

But a certain degree of fatigue remains with the risk of a rupture and the immobilization of the engine powered by the ramp.

Purpose of the invention

The present invention aims to develop a method for improving the fatigue life of the common rail of an injection system. The invention also aims to develop an injection system ramp obtained by such a method.

Presentation and advantages of the invention

To this end, the subject of the present invention is a method of treating the edge of the radial bores of the connection ends of the injectors with the axial chamber of a common rail of an internal combustion engine injection system, method according to which the outlet of the radial bores is trimmed in the chamber of the common rail.

According to the invention, this method is characterized in that a junction ring is produced in the form of a surface comparable to a surface of revolution along the axis of the bore, generated by a crown generator located on the axis of revolution in leveling the edge of the opening of the radial holes in the axial chamber by projecting onto the surface of the axial chamber and onto that of the radial holes.

The surface of the junction ring at the outlet of each radial hole in the chamber of the common rail allows the effects of cyclic pressure variations in the boom to be distributed, avoiding concentrating these effects on the edge as is the case with an edge simply deburred according to the state of the art.

The treatment method is further characterized in that the junction ring is generated by a generator, one end of which is a point on the surface of the radial bore, the other end is a point on the surface of the axial chamber, the relative position of the ends on the surface of the radial bore and on that of the axial chamber determines the respective grip of the junction ring on the surface of the radial bore and on the surface of the axial chamber.

Thus, the generator making a certain angle relative to the axis of the radial bore, it generates a generally frustoconical surface.

According to another advantageous characteristic, the generator is an arc of a circle convex relative to the axis of the radial bore, a straight line segment, a broken line, a segment with concave curvature relative to the axis, a combination of curved segments concave and convex.

In a particularly advantageous manner, a residual compression stress is induced at least locally in the surface of the junction ring. This residual compression stress is notably induced with the tool making the junction crown.

According to another advantageous characteristic, the surface of the junction ring has a width of between at least 0.1 and 0.5 mm.

The angle made locally by the generator is advantageously chosen as a function of the residual compression stress to be introduced into the surface of the junction ring.

This residual stress itself depends on the material of the ramp and the operating conditions and in particular it depends on the elastic limit of the material of the ramp.

According to another advantageous characteristic, the generator is a straight line of inclination between 40 ° and 55 ° relative to the axis of revolution.

Advantageously and as indicated, the tool which produces the junction crown induces the residual compressive stress in the surface of the crown during the same operation. This residual compression stress reduces the fatigue effect of large cyclic variations in pressure in the common rail.

The overall angle of the junction ring is advantageously between 40 ° and 55 °, which leads to an optimal distribution of the cyclic stress exerted on the surface of the ring during the operation of the ramp. This distribution is optimal with regard to the residual resistance and the risk of pre-damage of this machined area at the junction of the radial bores and the bore of the axial chamber.

The subject of the invention is also a common rail of an injection system obtained by the method as described above, this rail being composed of a body provided with an axial chamber into which the radial holes of the nozzles integrated in the body and used to connect the injectors or other equipment to the boom.

The outlet for the radial bores for connecting the injectors with the chamber of the common rail comprises a junction ring at the meeting of each radial bore and the axial chamber of the common rail.

Advantageously, the upper edge and the lower edge of the surface of the junction ring respectively join the surface of each radial bore and the surface of the axial bore of the chamber with a fillet.

Drawings

The present invention will be described below in more detail with the aid of exemplary embodiments of a common ramp with a junction ring in the form of a surface of revolution at the junction edge between a radial bore and the chamber. axial, shown in the following drawings, on an enlarged scale, in which:

Figure 1 is a sectional view of a common rail according to the invention, Figure 2 shows in its parts 2A, 2B on the one hand, an axial sectional view of the common rail at a radial bore by a plane containing the axis of the axial chamber and the axis of the radial bore, and on the other hand, a view in section through a plane perpendicular to the axis of the axial chamber and passing through the axis of the radial bore, before applying the method of the invention, FIG. 3 shows:

* in its parts 3A, 3B, corresponding to the section planes of FIGS. 2A, 2B, shows a first general embodiment of the junction ring at the edge of the two bores according to the invention, * in its parts 3C, 3D a second embodiment of the junction ring at the edge of the two bores, controlled by the cutting edge, FIG. 4, in its parts 4A, 4B, shows sectional views corresponding to the cutting planes of the figure 2, another embodiment of the junction ring at the edge of the radial bore and of the axial chamber, with a generator in the form of a broken convex line with two segments, FIG. 5 shows in its parts 5A, 5B, and according to cutting planes identical to those of FIG. 2, another embodiment of a junction ring according to the invention, generated by a convex curved generator, FIG. 6, in its parts 6A, 6B, shows a view in section according to identical section planes to those of FIG. 2 of another embodiment of a junction ring generated by a generator combining a concave curved arc form and a convex curved arc form, FIG. 7 in its parts 7A, 7B, is a sectional view along the section planes identical to those of FIG. 2, showing another embodiment of a junction ring with a generator in the form of a concave broken line formed by two segments.

Description of embodiments of the invention

According to Figure 1, the invention relates to a method for improving the resistance to fatigue of a common rail 100 of the injection system according to Figure 1. This common rail 100 consists of a body 1 forged hot in which is pierced an axial chamber 11 receiving the fuel to be put under very high pressure to supply the injectors. The ramp has end pieces 2 integrated with radial holes 21 opening into the axial chamber 11 of the body 1 to receive the end of the pipes connected to the injectors.

The ramp 100 has a number of integrated nozzles 2 depending on the number of injectors to be supplied and the number of inputs required for the high pressure pump. One end 101 generally comprises the pressure sensor; its other end 102 receives the pressure limiter or regulator returning the fuel by exceeding by the outlet nozzle 103 to the tank. When one or other of the above components is not required or installed differently, the ends 101 and 102 can also receive a plug or an additional end piece identical to the end pieces 2. These various pieces of equipment are not represented.

As the production of the radial holes generates a sharp edge and leaves barbs at the junction with the axial chamber 11, this edge is worked with a tool which produces a junction crown 3 as will be described below.

Figure 2, in its parts 2A, 2B, shows the state of the edge 22 of a bore 21 opening into the axial chamber 11 by the section of the common rail 100 by two perpendicular planes containing the axis ZZ of the bore radial 21:

part 2A is a section through a plane containing the axis ZZ and the axis XX of the axial bore 11, FIG. 2B is a section through a plane containing the axis ZZ and the transverse axis YY, perpendicular to the axis XX of the direction of the axial bore 11.

The intersection of the radial bore 21 with the axial bore 11, both considered as cylindrical surfaces of circular section 2IS, 11S, is an intersection curve 22 in three dimensions (X, Y, Z) of the fourth degree. As the diameter of the radial bore 21 is smaller than that of the axial bore 11, the radial bore 21 “descends” in the axial bore 11 in the side section view of FIG. 2A whereas in the section view of FIG. 2B, the intersection curve 22 is "contained" in the surface 11S of the axial bore 11 and merges with the arc of a circle of the section of the surface 11S of the chamber 11. The highest "generator" of the surface 11S (cylindrical surface generated by a straight line) bears the reference XoXo.

The sectional views through the two perpendicular planes according to parts 2A, 2B of FIG. 2 will be used in the following description.

To facilitate the interpretation of the drawings and the description of the process, it is useful to locate the four intersection points (22B, 22H) of the curve 22 and the two section planes. The difference in height (e) along the ZZ axis between the two low points 22B and the two high points 22H of curve 22 is also highlighted.

The dimensions of the holes 21 and those of the axial chamber 11 are not to scale and are greatly enlarged to facilitate the presentation of the invention and the geometry of the curves. The same is true of the drawing elements relating to the junction ring 3 described in its various embodiments. Finally the concepts up / down and right / left relate only to the orientation of the figures.

FIG. 3 shows two embodiments of the method consisting in producing a junction ring 3 in the form of a surface comparable to a surface of revolution 3S (along the axis ZZ) also called the axis of revolution of the radial bore 21 by leveling the edge 11 of the outlet of the surface 11S in the axial chamber 11.

This junction ring 3 is made as a surface generated by a straight or curved generator as will be explained and the apex S of which is located on the axis ZZ.

In the first, simplest case, the vertex S is fixed on the axis of revolution ZZ. The joining ring is, for example, generated by a tool having schematically an edge formed by the generator and which rotates around the axis ZZ.

In the second case, the rotating generator is controlled on the cutting edge 22; this enslavement can be done by physically following the edge 22 or by a command from the theoretical curve 22 of intersection of the two surfaces 11 S, 21S which are cylindrical surfaces of circular section. In the second case, the top Sv of the surface which is the point of intersection of the generator and the axis ZZ is not fixed but moves on the axis of revolution ZZ according to a race corresponding to the difference in height (e ) from edge 22.

While in the first case, by way of example, the intersection of the generator and the surface 21S is a circle, in the second case, the geometric location of this intersection with the surface 21S is a curve translated from the curve representing the edge 22. Since the drop (e) is small, the leveled surface is close to a surface of revolution.

As the presentation of the method according to the first case is geometrically simpler since the vertex S of the cone generated by the generator is fixed, this description will be made first and that of the second case will be in a way an extrapolation of the first description.

FIGS. 3A, 3B show the first embodiment of a junction ring 3 which is a surface of revolution 3S generated by a generator 31g rotating around the axis ZZ and delimited by an upper point 32P and a lower point 33P. The generator 31G cuts the axis of revolution ZZ at point S constituting the top of the cone of revolution which it generates. While the upper point 32P describes a circle 32 on the surface 21S, the lower point 33P describes a circle in a plane perpendicular to the axis ZZ. But this circle 33 is not the lower edge 34 of the junction ring 3 and it only coincides with the lower edge 34 in the plane ZZ / XX (FIG. 3A). This generator 31g of the surface of revolution 3S is for example the active surface (cutting edge) of a rotary tool of the milling cutter type, engaged in the radial bore 21 and then deployed therein so as to overlap the curve d intersection 22 of the radial bore 21 of axis ZZ and of the surface 11S of the axial chamber 11, of axis YY.

The generator 31g attacks the surface 21S of the radial bore 21 by forming the upper circular edge 32 of the junction ring 3, described by point 32P.

The lower edge 34 of the surface 31S of the junction ring 3 is the curve described by the intersection (current point 34P) of the generator 31g and of the surface 11S of the axial bore 11 because this intersection is located by definition on the surface 11 S, whatever the angular position of the generator 31g around the axis of rotation ZZ.

In other words, the lower end 33P of the generator 31g describes a circle in a plane perpendicular to the axis ZZ while during this rotation of the generator 31g (supposedly contained in a plane passing through the axis ZZ) around from the axis ZZ, the current point 34 P is at the intersection of the generator 31g and the surface 11S; during the generator rotation, it moves on the 33P-34Po segment of the generator 31g between the lowest point 33P and the highest intersection point 34Po.

The curve 34 appears in the section in side view of FIG. 3A. It corresponds to a sort of three-dimensional ellipse with two planes of symmetry; in projection in the plane XX, ZZ (figure 3A) it is very flattened at the lowest points (33Po) and at the highest points (34Po) (figure 3A).

It should be noted that the figures used in this description are limited to the sections by the two planes XX / ZZ and YY / ZZ which correspond to the extreme positions of the generator 31g; the intermediate positions which are complex to represent in section view would complicate the presentation.

Figures 3A, 3B are divided into two parts by the axis ZZ to facilitate presentation and geometric constructions with the extension lines between Figures 3A, 3B.

The right part of FIG. 3A shows the section of the surface 3S with the generator 31g in the plane XX / ZZ, the circular shape of the upper edge 32 and the three-dimensional curve 34 of the lower edge of this frustoconical surface 3S of the crown junction 3.

The left part of FIG. 3A shows the generator 31g in the XX / ZZ plane with its two ends 32P and 33P and the current point 34P at the intersection of the highest line XOXO of the surface 11S. In this position, the current point 34P bears the reference 34Po.

The intersection edge 22 has been shown, to show the spread of the surface of revolution 3S above and below this line 22 which disappears by the production of the junction crown 3.

The right part of Figure 3B shows the sectional view before the edge 22 is leveled. The edge 22 being cut in the surface 11S, its projection in the YY / ZZ plane is an arc of a circle delimited by the low points 22B and arriving up to the two high points 22H combined on the XOXO generator.

The left part of FIG. 3B shows the generator 31g and its end 32P on the surface 21S and its end 33P on the surface 11S. In these two extreme positions, point 33P bears the reference 33Po. The right part of FIG. 3B shows the departure of edge 22 in the plane YYI7JL.

The two curvilinear arrows indicate the progression on the surface 11S of the current point 34P going up to the upper right XoXo by the rotation of the generator 31g.

Figures 3C, 3D show sectional views corresponding to the second embodiment of the method, according to which the intersection Sv of the generator 31gv with the axis of rotation ZZ is slaved to the cutting edge 22. This can be diagrammed in that the intersection Sv moves on the axis ZZ on a path of length (e) equal to the height difference of the curve of the edge 22.

This means that the high point 32P of the generator 31gv which is its intersection with the surface 21 S, no longer moves on the circle 32 but on a curve 22V which corresponds to the translation of the curve 22 along a height H. This height is visible in Figure 3C. This translation means that the rotation of the generator 31gv is combined with a translation of length (e).

The point of intersection 34P of the generator 31gv with the surface 11S describes a curve 34v comprised between the curve 22 and the curve 34 of the generator 31G of the first embodiment; this curve 34 has been plotted in FIG. 3C for comparison.

The area of the crown 3Sv obtained is thus slightly reduced compared to that of the crown 3S of a generator 31g with a fixed top S. The difference between these two surfaces is all the more reduced since the practical realization of these surfaces is on a very small scale compared to that of FIGS. 3A-3D.

The description of the different variants will be given below in the case of conical surfaces with fixed apex, the application to the case of a surface generated by a generator controlled by the edge 22 being deduced therefrom simply.

FIGS. 4A, 4B show, under the same conditions of representation as above, the case of a generator 41g in the form of a broken line convex relative to the axis ZZ and composed of two segments of line 41gl, 41g2 joining at point 41g3.

To facilitate the description, the generator 41g is shown combined with the generator 3 lg in FIGS. 3A, 3B; the previous references have been kept if possible except for the modified elements.

The generator 41g cuts the edge 22 according to a bicone of revolution around the axis ZZ; the two parts 3S1, 3S2 of this bicone forming the surface of revolution around the axis ZZ of the junction ring 3 meet by a circular edge 35 (2D curve) if the junction point 41g3 is above the 11S surface or a 3D curve if the junction point 41g3 is below the high straight line XoXo and flows on the 11S surface. The curve described in this case by point 41g3 is formed by an arc of a circle around the axis ZZ from the position shown in FIG. 4B until point 41g3 touches the surface 11S and the segment (41g3-41gl) begins to penetrate the 11S surface. From this position, the curve is a part of the curve of a generator (41g4-32P) described by the current point 41g4 (the current point 41g4 is then the equivalent of point 33P of the generator 31g) and thus having a shape similar to that of the curve of curve 34 in FIGS. 3A, 3B but smaller. This combination of curve arcs generated by point 41g3 is symmetrical with respect to the two section planes XX / ZZ and YY / ZZ like all the curves in the different figures.

The lower edge 44 of this 3S bicone (3S1, 3S2) is a three-dimensional curve, in the shape of an ellipse deformed in three dimensions, crushed, arriving on the right XoXo at the high positions 44Po below the points 34Po shown at title marks and inside the curve 34 by being tangent to the two lowest points 33Po on the surface 11S.

FIG. 5, in its parts 5A, 5B, shows the case of a generator 51g delimited by the same points, upper and lower 32P, 33P than the generator 31 described above and cutting the edge 22.

It should be noted that this generator from point 33P is at most tangent to the surface 11S.

If the generator were to cut this surface 11S in its position closest to the surface 11S (according to FIG. 5B), for example by a foray into the axial chamber 11, through the surface 11S in order to "come out" at point 331P ( FIG. 5B), it would suffice to simply take as the generator the part comprised between points 33IP and 32P instead of the generator 51g comprised between points 32P and 33P.

This would give a lower edge 541 closer to curve 22 than is edge 54.

FIG. 5A shows for comparison, the generators 51g and 511g and the curves 54 and 541.

The 3S surface is a conical surface generated by a generatrix curved around the ZZ axis, the convexity being defined here with respect to the ZZ axis.

FIG. 6 shows in its parts 6A, 6B, a generator 61g composed of two curved arcs 61gl, 61g2 one of which is convex and the other concave with respect to the axis of rotation ZZ. This generator generates a 3S conical surface with double curvature.

FIG. 7 shows, in its parts 7A, 7B, a surface of revolution 3S generated by a concave generator 71g, a compound of two straight lines 71gl, 71g2 meeting at point 71g3.

The surface 3S obtained is delimited as in the previous examples by an upper edge 32 in the form of an arc of a circle in the surface 21S and a lower edge 74 formed by a curve of the fourth degree in 3D which is beyond the curve 34 of the generator 31g presented for comparison.

The surfaces 3S of the junction crowns 3 generated by the different generators 31g-71g given by way of nonlimiting examples can be worked to induce a residual stress therein with the tool carrying the generator or with a separate tool.

Likewise, the raised edges, for example the upper edge 32 and the lower edge 34, 44, 54, 64, 74 of the surface 3S, can be attenuated by a fillet.

It should also be noted that the overall angle of a generator, that is to say the angle of the straight line joining the ends 32P, 33P of the generators, is preferably an angle between 40 and 55 °.

The generator segment angle such as for example the generator 41g or the generator 71g is advantageously between 25 ° and 40 °.

Finally, the width of the surface 3S generated by the generator behind the drilling edge 22 is advantageously of the order of 0.1-0.5 mm between the narrowest parts and the widest parts. This width is the distance between points 32P and 34P (current points) which is the variable length segment of the generator which generates the surface 3S of the junction ring.

NOMENCLATURE OF MAIN ELEMENTS

100 Common rail

101 End of the ramp / entrance to the axial chamber

102 End of the boom / end receiving the pressure relief valve

103 Outlet end

Ramp body

Axial chamber

11S Surface of the axial chamber

Integrated tip

Radial drilling

21S Radial hole surface

Grinding edge / intersection curve

Junction crown

3S Surface of revolution of the junction crown

31g, 41g, 51g, 61g, 71g Generators

Upper edge of the surface of revolution

32P Upper point of the generator

Curve described by the lower point 33P of the generator

33P Lower generator point

Lower edge of the 3S surface of revolution

34P Generator and surface intersection point 21 S / current point

Curve described by the junction point of two generator segments

S Fixed top

Sv Mobile Summit

ZZ Radial drilling axis / axis of revolution

Claims (12)

R E V E N D 1 C A T I O N S 1 °) Process for treating the edge of the radial bores (21) of the nozzles (2) for connecting the injectors with the axial chamber (11) of a common rail (100) of an internal combustion engine injection system , method according to which the outlet of the radial bores (21) of axis (ZZ) is trimmed in the chamber (11) of the common rail, method characterized in that a surface-shaped junction crown (3) is produced comparable to a surface of revolution (3S) along the axis (ZZ) of revolution generated by a vertex generator (S, Sv) located on the axis (ZZ), by leveling the edge (22) of the opening of the holes radial (21) in the axial chamber (11) projecting over the surface (11S) of the axial chamber (11) and on that (21S) of the radial holes (21). 2 °) treatment method according to claim 1, characterized in that the vertex (S) which is the intersection of the generator (31 G) with the axis (ZZ) is fixed. 3 °) treatment method according to claim 1, characterized in that the vertex (Sv) which is the intersection of the generator (31gv) with the axis (ZZ) is controlled on the edge (22). 4 °) treatment method according to claim 1, characterized in that the junction ring (3) is generated by a generator (31g, 31gv, 41g, 51g, 61g, 71g) of which: one end (32a) is a point on the surface (21 S) of the radial bore (21), the other end (33a) is a point on the surface (21 S) of the axial chamber (21), the position relative of the ends (32a, 33a) on the surface (21 S, 11 S) of the radial bore (21) and that of the axial chamber (11) determining the respective grip of the junction ring (3) on the surface (21 S) of the radial bore (21) and on the surface ( US) of the axial chamber (11). 5 5 ^Ü ) treatment method according to claim 4, characterized in that the generator (31g, 41g, 51g, 61g, 71g) is an arc of a circle convex relative to the axis (ZZ), a straight line segment, a broken line, a segment with a concave curvature with respect to the axis (ZZ), a combination of segments concave and convex curves. 6 °) Treatment method according to claim 1, characterized in that a residual compressive stress is induced in the surface (3S) 35 of the junction ring (3). 7 °) Treatment method according to claim 6, characterized in that the residual stress is induced with the tool making the junction crown (3). 8 °) treatment method according to claim 1, characterized in that a junction ring surface (3) with a corn25 width taken between 0.1 and 0.5 mm is produced. 9 °) treatment method according to claim 1, characterized in that the generator is a straight line of inclination between 40 ° and. 55 ° relative to 30, to the axis (ZZ). 10 °) Common rail of the injection system obtained according to the method of any one of the preceding claims, composed of a body (1) provided with an axial chamber (11) into which the radial holes (21) of the nozzles (2) integrated in the body (1) for connecting the injectors, characterized in that the outlet of the radial holes (21) for connecting the injectors S with the chamber (11) of the common rail (100) has a ring junction (3) at the meeting of each radial bore (21) and the axial chamber (11) of the common rail (100). 11 °) common ramp according to claim 10, 10 characterized in that the surface (3S) of the junction ring (3) has at least locally a residual compression stress induced with the tool making the junction ring. 15 12 °) common rail according to claim 10, characterized in that the upper edge (32) and the lower edge (33) of the surface (38) of the connecting ring (3) respectively join the surface (21 S) of the radial bore (21) and the surface of the axial chamber (11S) of the bore 20 (11) with a leave.