FR2874408A1 - FUEL INJECTION INSTALLATION FOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Fuel injection installation comprising at least one valve (23) which controls a fuel connection. The valve (23) comprises a member (52) guided by at least one guide segment (152) in at least one bore (54). The valve member (52) has a sealing surface (60) for cooperating with a valve seat (62) and controlling the fuel connection. The guide segment (152) of the valve member (52) comprises at least by area a convex domed outer contour.

Description

Field of the invention

  The present invention relates to a fuel injection installation of an internal combustion engine comprising at least one valve controlling a fuel connection, the valve having a valve member guided by at least one guide segment in at least one bore, the valve member having at least one sealing surface by which it cooperates with at least one valve seat to control the fuel connection.

  State of the art Such a fuel injection installation is known from DE 101 19 984 A. This fuel injection installation comprises a valve which controls at least one fuel connection. The valve includes a valve member having a sealing surface cooperating with the valve seat to control the fuel connection. The valve member is slidably guided in the bore or bore of a portion of the housing of the fuel injection system. The valve member has at least one guide segment, guided in a bore, and in this con-nue valve there are two guide segments offset in the direction of the longitudinal axis of the valve member.

  The fuel injection installation according to DE 101 19 984 A constitutes a pump-nozzle or pump-injector system with a high pressure fuel pump and an injector connected thereto for each cylinder of the internal combustion engine. . The valve is an electromagnetic control valve that controls fuel injection. The valve member controls the connection between the working chamber of the high-pressure fuel pump and a discharge zone. The guiding segments of the valve member have the function of centering and sealing; these guiding segments have a cylindrical outer contour. The two guide segments of the valve member are housed in a bore each made in different parts of the housing. One part of the housing is the pump body and the other part is that of the electromagnet. Because of the shape and position tolerances, in particular the holes in the housing parts and the mounting defects of the two housing parts with respect to each other, it is difficult to provide a defined guide and it is possible to thus have fault positions for the valve member. This fault position is accentuated by the hydraulic, magnetic and elastic functional forces acting on the valve member, since these forces have transverse components and thus position the valve member at an angle, inter alia during its opening stroke. . This increases the friction between the valve member and the bore, particularly at the end zones of the bores, which generally have an irregular or even sharp edge transition. This friction results in instabilities of operation of the valve and, thus, dispersions of the instant and / or the injected fuel dose.

  DESCRIPTION AND ADVANTAGES OF THE INVENTION The present invention relates to a fuel injection plant of the type defined above, characterized in that the guiding segment of the valve member comprises at least in zone a convex convex outer contour. This arrangement has the advantage of shifting the friction points between the guide segment and the bore towards the middle of the guide segment, and to give the poppet member an additional degree of freedom improving the centering function. . This improves the operation of the valve and allows a more precise control of the fuel injection.

  According to another advantageous characteristic the valve member comprises two guide segments offset relative to each other in the direction of its longitudinal axis, provided respectively in a bore and of which at least one guide segment has, at least by sector, a convex convex outer contour. This improves the guiding of the valve member.

  Preferably in this case, the two guide segments of the valve member have different diameters.

  According to another advantageous characteristic at least one guide segment of the valve member separates, in a sealed manner, a high pressure zone from a low pressure zone.

  In this case, advantageously, the guiding segment, which ensures the high pressure seal of the valve member, has a greater longitudinal extension in the direction of the longitudinal axis of the valve member than the other. guide segment. This reduces the leakage of the high pressure zone.

  According to another advantageous characteristic, the sealing surface of the valve member is provided between the two guide segments of the valve member.

  According to another advantageous characteristic, the two guide segments of the valve member are each provided in a bore of different housing parts of the fuel injection installation.

  The zone convex convex outer contour allows at least one guide segment to compensate for positioning defects related to the tolerances of the two housing parts.

  According to other advantageous features: at least one guide segment of the valve member, seen in the direction of the longitudinal axis of the valve member, has a central zone having an at least substantially cylindrical or frustoconical outer contour; and, adjacent on both sides thereof, marginal areas having a convex convex outer contour.

  at least one guide segment of the valve member has, in the direction of the longitudinal axis of the valve member, a central zone having an outer contour curved on a convex shape and, adjacent to on either side of it, the marginal areas having an outer contour at least substantially cylindrical or frustoconical.

  These features allow a precise adaptation of the outer contour of a guide segment of the valve member to different mounting conditions of the valve member.

  According to other advantageous features: the convex convex outer contour of the guide segment is made at least substantially in a circular or elliptical arc; transitions between the central zone and the marginal zones of the guide segment of the guide segment; valve members are rounded, - the valve is a high-pressure discharge control valve of a high-pressure fuel pump of a fuel injection system, - the valve is a relief valve whose movement of the valve member allows the pressure in the working chamber of a high-pressure fuel pump of a fuel injection installation to be discharged from time to time.

  Drawings The present invention will be described below in more detail with the aid of several embodiment examples shown schematically in the accompanying drawings in which: FIG. 1 shows a fuel injection installation of a corresponding internal combustion engine to a first exemplary embodiment according to a simplified representation, FIG. 2 shows on an enlarged scale an injector of the fuel injection installation, FIG. 3 shows another enlarged view of an element of the fuel injector. FIG. 4 shows an alternative embodiment of the injector element, FIG. 5 shows another alternative embodiment of the injector element; FIG. 6 shows a second embodiment of an installation of FIG. fuel injection corresponding to detail VI of FIG. 1, and FIG. 7 shows a third exemplary embodiment of the corresponding fuel injection installation. t in detail VII of FIG.

  Description of embodiments

  FIG. 1 shows a fuel injection installation of an internal combustion engine corresponding to a first embodiment of the invention. The fuel injection system comprises, for each cylinder of the internal combustion engine, a high-pressure fuel pump 10 and an injector 12 connected to the pump. The high-pressure pump 10 and the fuel injector 12 can be combined into an assembly also called pump-injector unit. The high-pressure fuel pump 10 and the fuel injector 12 may however also be embodied as separate elements connected by a fuel line.

  The high-pressure fuel pump 10 comprises a pump body 14 in which a pump pis-ton 18 is guided in leaktight manner in a cylinder or bore bore 16. The pump piston is driven by the pump cam. a camshaft of the internal combustion engine against the force developed by a return spring 19 to perform a translational movement. The pump piston 18 delimits a working chamber 22 in the bore 16. The fuel is compressed at high pressure by the pump piston 18 performing its delivery stroke in the chamber 22. The working chamber 22 of the pump is connected at a low pressure zone controlled by an electrically controlled control valve 23. The control valve 23 is controlled by an electronic control installation 25. In the low pressure zone, for example, a high pressure is generated by means of the discharge pump 21 to fill the working chamber 22 during the suction stroke of the pump piston 18. The delivery pump 21 draws fuel from a reservoir 24.

  The injector 12 consists of a body 26 which can be made of several parts and is connected to the pump body 14. A bore 30 of the body 26 of the injector receives an injection valve member or injector needle 28 sliding longitudinally. The bore or bore 30 is at least substantially parallel to the cylinder 16 of the pump body 14, but it can also be inclined with respect thereto. The body 26 of the injector comprises, at its end located on the combustion chamber side of the internal combustion engine cylinder, at least one ejection orifice 32 and preferably several such ejection orifices. The injector needle 28 has, at its end zone situated on the combustion chamber side, a sealing surface 34, for example substantially conical, cooperating with a valve seat 36 which is also substantially conical in shape. level of its end zone facing the combustion chamber. The ejection orifices 32 leave this valve seat.

  Between the injector needle 28 and the bore 30, on the valve seat 36 side, the injector body 26 has an annular volume 38 whose end zone is opposite to that of the seat The pressure valve 40 is joined by a radial enlargement of the bore 30, a pressure chamber 40 which surrounds the injector needle 28. The injector needle 28 comprises, at the level of the pressure chamber 40, a shoulder of pressure or thrust 42 turned to the sou-pope seat 36 and made by a section reduction. The end of the injector needle 28, opposite the combustion chamber, is subjected to a prestressing closing spring 44 which pushes the injector needle 28 against the valve seat 36. closing spring 44 is housed in the spring chamber 46 formed by a bore in a spring support forming part of the body 26 of the injector and which is connected to the bore 30. The pressure chamber 40 comprises the communication 48 with the working chamber 22 of the pump, through the body 26 of the injector and the body 14 of the pump.

  The control valve 23, shown on a scale enlarged in FIG. 2, is controlled for example by an electromagnet 50 constituting an actuator. The electromagnet 50 is housed in a housing connected to the pump body 14. The electromagnet 50 is installed for example on the side of the pump body 14. The control valve 23 comprises a valve member 52 which slides, for example, at least substantially perpendicular to the longitudinal action 17 of the bore 16 of the cylinder. The valve member 52 is guided in a bore 54 of the pump body 14 and in a bore 56 of a portion 58 of the housing of the electromagnet 50. The valve member 52 thus comprises a first guide segment 152 in which the piercing 54 of the pump body 14 and a second guide segment 252 in the bore 56 of the housing part 58. The two guide segments 152, 252 of the valve member 52 are offset in the direction of the axis 53 of the valve member 52. The second guide segment 252 of the valve member 52 and the bore 56 of the housing portion 58 may have a larger diameter than the first guide segment 152 and the bore 54. of the pump body 14. The bore 54 of the pump body 14 may be a blind hole, ending in the pump body 14 or a through bore closed by a closure member on the opposite side to that of the electromagnet 50.

  The valve member 52 has a sealing surface 60 between the two guide segments 152, 252. This sealing surface is formed by the annular shoulder of the valve member 52 corresponding to a diameter variation of this member 52, opposite the electromagnet 50. The sealing surface 60 of the valve member 52 cooperates with the valve seat 62 formed by the edge of the bore 54 in the pump body 14 on the facing side. the electromagnet 50. The sealing surface 60 and the valve seat 62 may have at least substantially a frusto-conical shape. The diameter of the bore 54, at the end zone facing the electromagnet 50, adjacent to the valve seat 62 is greatly increased so as to limit the annular volume 64 surrounding the valve member 52 by the body. pump 14 and the housing portion 58, annular volume connected to the low pressure zone. In the area between the valve seat 62 and the bore 54 guiding the first guide segment 152 of the valve member 52, the bore 54 has a radial extension 55 into which a bore 66 passes through the pump body. 14. This also opens into the working chamber 22 of the pump. The valve member 52 may have a shank 51 of smaller diameter than that of the guide segment 152, so as to leave an annular gap between the shank 51 and the bore 54.

  The valve member 52 is firstly subjected to the pressure of the armature 68 of the electromagnet 50 and, secondly, to that of a pre-stressed return spring 70 installed between the body valve 52 and the bottom of the drilling 54 in the form of a blind hole, or the shutter element 72 of the bore 54. The return spring 70 urges the valve member 52 in the direction of its opening. In this di-rection, the sealing surface 60 of this member is raised from the valve seat 62. When the electromagnet 50 is energized, the valve member 52 is moved by the armature 68 against the developed force by the return spring 70 in the closing direction until coming with its sealing surface 60 bearing against the valve seat 62.

  When the valve member 52 is closed, there prevails in the extension 55 of the bore 54, the same high pressure as in the working chamber 22 of the pump. The seal against the annular volume 64 is through the sealing surface 60 of the poppet member 52 applied against the valve seat 62. The sealing vis-à-vis the zone d the end of the bore 54, in which the return spring 70 is located, is by the first guide segment 152 of the valve member 52, guided with a small radial clearance in the bore 54. The first guide segment 152 has an extension as large as possible in the direction of the longitudinal axis 53 of the valve member 52 to ensure sealing and reduce leakage. The second guide segment 152 of the valve member 52 has a much smaller radial extension in the direction of the longitudinal axis 53 because, at this point, it is not necessary to provide the sealing against high pressure.

  Figure 3 shows on a larger scale a detail of the valve member 52 at its first guide segment 152. The guide segment 152 thus has, at least in areas, a convex outer contour in a convex shape. In the embodiment of FIG. 3, the guide segment 152 has a median zone 152a having an outer contour at least substantially cylindrical or convex, continuing on either side by marginal zones 152b, of outer contour convex in a form convex or at least a substantially frustoconical shape. The outer contour of the marginal zone 152b is convexly curved in the longitudinal sections of the valve member 52 passing through its longitudinal axis 53. The longitudinal extension of the edge zone 152b in the direction of the longitudinal axis 53 may be variably selected depending on the frictional action points and may be larger or smaller than the longitudinal extension of the central zone 152a. The longitudinal extensions of the two marginal zones 152b in the di-rection of the longitudinal axis 53 may be identical as shown in Figure 3; but these segments can also be different. The convex curvature of the marginal areas 152b of the guide segment 152 is made for example by rounding the envelope surface of the guide segment 152 along a radius R2. The radius R2 may be between about 100 mm and 25,000 mm; the length of the guide segment 152, between about 10 mm and 50 mm, gives a curvaceous shape very slightly convex. For the two marginal areas 152b, one can provide the same radius R2 or different R2 radii. For one of the marginal areas 152b, for example the left marginal area, one can have a radius R2 of about 10,800 mm and for the other marginal area 152b, the right marginal area, one can have a radius R2 of about 21,000 mm. The passage between the marginal zones 152b and the central zone 152a of the guide segment 152 is, for example, rounded off with another radius R1. The radius R1 rounded may be between 0.1 mm and 100 mm. Between the marginal areas 152b and the central zone 152a on both sides, identical or different rounding radii R1 may be provided. Instead of a radius of radius R1 or R2, it is also possible to have an elliptical sectional contour.

  FIG. 4 shows a detail of the valve member 52 whose first guide segment 152 differs from that of FIG. 3. In the embodiment of FIG. 4, the central zone 152c of the guide segment 152 has a convex outer contour on a convex shape while the adjacent marginal areas 152d of both sides each have an outer contour at least substantially cylindrical or tronconic. The outer contour of the central zone 152c is curved in a convex shape in the longitudinal torques of the poppet member 52 passing through its longitudinal axis 53. The longitudinal extension of the central zone 152c, in the direction of the longitudinal axis 53, is greater than the longitudinal extension of the marginal zone 152d.

  The longitudinal extensions of the two marginal zones 152d are at least substantially identical, so that the guide segment 152 has a symmetrical shape. The convex curved portion of the central zone 152c of the guide segment 152 is made for example by rounding the envelope surface of the guide segment 152 with a radius R2 so that the outer contour will at least substantially have a shape of a circle segment. The radius R2 may be between about 100 mm and 25,000 mm and the length of the guide segment 152 may be between about 10 mm and 50 mm with a convexly convex portion. The transition between the marginal areas 152d and the central zone 152c of the guide segment 152 is, for example, rounded with another radius R1. The rounding radius R1 may, for example, be between 0.1 mm and 100 mm. Instead of rounding with a radius R1 or R2, one can also have an elliptical shape contour. The embodiment of the guide segment 152 according to FIG. 5 differs from that of FIG. 4 only in that the longitudinal extensions of the marginal zones 152 are different, which gives an asymmetrical guide segment 152. It can also be provided that the entire first guide segment 152 has a contour in the form of a circular arc of a certain radius or an elliptical contour, giving a convex curved shape.

  The second guide segment 252 of the poppet member 52 can be made as the first guide segment 152 described above with reference to FIGS. 3 to 5.

  As the bores 54, 56 receiving the valve member 52 with its guide segments 152, 252 can be made in different parts connected to each other, the manufacturing tolerances necessarily lead to differences in the arrangement of the bores 54, 56 which They can not be exactly coaxial as is shown in a greatly exaggerated manner in FIG. 2. In particular, during the opening movement of the valve member 52, when the latter sees its sealing surface 60 away from the valve seat 62 under the effect of the force of the return spring 70, the valve member 52 can take an angled position. As the first guide segment 152 rests in the bore 54 by its outer contour, at least bulging by zone, near its central segment 152a, 152c of the guide segment 152, it avoids seizure. The bearing points of the guide segment 152 in the bore 54 are marked with circles in FIG. 2. During the closing movement of the valve member 52, the latter can tilt in the bore 54 around its first guide segment 152, which facilitates the centering of the sealing surface 60 of the valve member 52 in the valve seat 62, thus enabling rapid and secure closure of the valve member 52. For the second segment of the guide 252 of the sub-poppet member 52, it also prevents seizure in the bore 56 of the housing portion 58 and thus an increase in friction.

  The control valve 23 controls the fuel injection by closing at a certain time during the discharge stroke of the pump piston 18, this instant being determined by the control installation 25 according to the operating parameters of the internal combustion engine. . Thus, a high pressure is established in the working chamber 22 of the pump, and thus also in the pressure chamber 40 of the injector 12. When the pressure in the working chamber 22 and thus that in the chamber of 40 is large enough that the force generated by this pressure, applied to the thrust shoulder 42, and acting on the injector needle 28 in the direction of its opening, exceeds the force developed by the closing spring 44, the injector needle 28 opens, which corresponds to the beginning of the fuel injection. At a time determined by the control installation 25, it opens again the control valve 23 which ends the fuel injection. Upon opening of the control valve 23, the high-pressure fuel escapes from the working chamber 22 of the pump and the pressure chamber 40 through the bore 66 and the radial extension 52 into the bore 54 and thence, through the annular gap existing between the rod 51 of the valve plate 52 and the bore 54, to pass into the annular volume 64 and thus be discharged to the low pressure zone.

  FIG. 6 shows a second exemplary embodiment of the invention of a fuel injector 12. The fuel injector 12 is essentially made as described above and comprises an injector needle 28 slidably guided in the body 26 of the injector. The injector needle 28 comprises a first guide segment 128 guided in the bore or bore 30. The first guide segment 128 of the injector needle 28 sealingly closes the pressure chamber 40 in which the high pressure reigns. pressure during the fuel injection, vis-à-vis the spring chamber 46 constituting a low pressure zone. The injector needle 28 further comprises a second guide segment 228 between the first guide segment 128 and the sealing surface 34 of the needle 28. The injector body 26 has, between the pressure chamber 40 and the valve seat 36, another bore 231 of reduced diameter with respect to it of the pressure chamber 40. The second guide segment 228 of the injector needle 28 is guided in this other bore 230. there remains a free passage segment between the second guide segment 228 and the guide bore 230 through which the fuel can exit the pressure chamber 40 to feed the ejection ports 32. At least one of the guide segments 128, 228 of the injector needle 28 is produced as described above with the help of Figures 3 to 5 and thus comprises, at least in a zone, an outer contour convex on a convex shape. But the injector needle 28 may also have only one guide segment 128 guided in the bore or bore 30.

  FIG. 3 shows a third embodiment of the invention provided with a relief valve 80, between the working chamber 22 of the pump and the spring chamber 46. The closing spring 44 thus rests at its end. opposite to that facing the injector needle 28 at least indirectly against the member 82 of the valve 80. The member 82 of the valve is slidably guided in a portion of the body 26 of the injector in a bore 84 which continues at least substantially coaxially with the spring chamber 46. The valve member 82 has a first guide segment 182 facing the working chamber 22 of the pump, this first segment being guided in the first segment 184 of the bore 84. The valve member 82 further includes a second guide segment 282 on the closing spring side 84. This second guide segment is guided in a second segment 284 of the bore 84. The second guide segment 282 of valve 82 and the second piercing segment 284 has a larger diameter than the first guide segment 182 and the first piercing segment 184. The second guide segment 282 of the valve member 82 guided in the second piercing segment 284 provides the sealing the working chamber 22 of the pump vis-à-vis the spring chamber 46. At the junction between the first piercing segment 184 and the second piercing segment 284, the portion of the injector body 26 has a valve seat 86 at least substantially of frustoconical shape. The valve member 82 has a sealing surface, for example at least substantially frustoconical, between the two guide segments 182, 282. This sealing surface cooperates with the valve seat 86. Between the front surface of the first segment 202, the valve member 82 and the working chamber 22 of the pump, there can be a throttling point 90 in the piercing segment 184. At least one of the guide segments 182, 282 of the Valve 82 is made, as described above with the help of Figures 3 to 5, to have at least a convex convex outer contour area.

  The operation of the relief valve 80 will be described hereinafter. When there is no high pressure in the working chamber 22 of the pump, the valve member 80 is held in abutment by its sealing surface 84 against the valve seat 86 by the closing spring 44. a discharge stroke of the pump piston 18, the control valve 23 being closed, a high pressure is established in the working chamber 22 of the pump, the front surface of the first guide segment 128 of the organ Valve 82 is biased by the high pressure in the working chamber 22. If the force generated by the high pressure exerted on the valve member 82 is greater than the force of the closing spring 44, the The poppet 82 moves to the spring chamber 46 and raises its sealing surface 88 with respect to the valve seat 86. The high pressure of the working chamber 82 of the pump then also acts on the sealing surface 88 of the pump. valve member 82, so that e-ci is subjected to a greater force in the direction of the opening. The movement of the valve member 82 in the opening direction is limited by a stop 92. The opening movement of the poppet member 82 decreases the pressure rise or relieves the pressure in the pressure chamber. work 22 of the pump and, in addition, the force of the closing spring 44 increases; the surfaces of the valve member 82, exposed to pressure, and the thrust pressure shoulder 42 of the injector needle 28 are made concordant so that the high pressure in the working chamber 22 of the The pump first opens the injector needle 28 while the valve member 82 remains in the closed position. This results in a pre-injection of a small amount of fuel and, upon the subsequent increase in pressure in the working chamber 22 of the pump, the valve member 82 which opens again assures the closure of the injector needle 28 and thus completes the pre-injection. When the increase in pressure in the working chamber 22 of the pump is continued, a greater force acts in the direction of opening on the injector needle 28 while the force developed by the closing spring 44 does not continue to increase; thus, the injector needle 28 opens for the main injection of a large amount of fuel. To complete the fuel injection, the control valve 23 is opened to unload the working chamber 22 from the pump.

  The valve may also be provided in any other zone of a fuel injection installation and this injection installation may also be performed differently than the pump-injector assembly described above, for example in the form a common rail injection system. The valve may be associated with an injector for controlling the opening of the fuel injector or associated with a high pressure reservoir or pump discharging high pressure fuel into the reservoir to control the pressure in the reservoir. .

Claims (14)

  1) Fuel injection plant of an internal combustion engine having at least one valve (23; 12; 80) controlling a fuel connection, the valve (23; 12; 80) having a valve member (52; 28; 82) guided by at least one guide segment (152,252; 128,228; 182,282) in at least one bore (54,56; 30,230; 184,284), the valve member (52; 28; 82) having at least one sealing surface (60, 34, 88) by which it cooperates with at least one valve seat (62, 36, 86) for controlling the fuel connection, characterized in that the guide segment (152, 252; 128.228 182,282) of the sub-poppet member (52; 28; 82) has at least a convex convex outer contour area.   2) Injection device according to claim 1, characterized in that the valve member (52; 28; 82) has two guide segments (152, 252; 128,228; 182,282) which are offset relative to one another. other in the direction of its longitudinal axis, respectively provided in a bore (54,56; 30,230; 184,284) and of which at least one guide segment (152,128,282) has, at least by sector, an outer contour curved convex.   3) Injection device according to claim 2, characterized in that the two guide segments (152,252; 128,228; 182,282) of the valve member (52; 28; 82) have different diameters.   4) Injection device according to claim 1, characterized in that at least one guide segment (152, 128, 282) of the valve member (52; 28; 82) separates, in a sealed manner, an area high pressure (55, 40, 22) of a low pressure zone (64, 46).   Injection plant according to claim 4, characterized in that the guide segment (152, 128, 282), which seals the valve member (52; 28; 82) at high pressure, a greater longitudinal extension in the direction of the longitudinal axis of the valve member (52; 28; 82) than the other guide segment (252,228,182).   6) Injection device according to claim 2, characterized in that the sealing surface (60; 88) of the valve member (52; 82) is provided between the two guide segments (152, 252). 182, 282) of the valve member (52; 82).   Injection plant according to claim 2, characterized in that the two guide segments (152, 252) of the valve member (52) are each provided in a bore (54; 56) of different housing parts. (14; 58) of the fuel injection system.   8) Injection device according to claim 1, characterized in that at least one guide segment (152) of the valve member (52), seen in the direction of the longitudinal axis (53) of the Valve member 52 has a central zone (152a) having an at least substantially cylindrical or frustoconical outer contour and, adjacent on both sides thereto, marginal zones (152b) having a convex convex outer contour.   9) Injection device according to claim 1, characterized in that at least one guide segment (152) of the valve member (52) has, in the direction of the longitudinal axis (53) of the organ valve (52), a central zone (152c) having an outer contour convex on a convex shape and, adjacent to either side thereof, the marginal zones (152d) having an outer contour at least substantially cylindrical or frustoconical.   10) Injection device according to claim 1, characterized in that the convex convex outer contour of the guide segment (152) is formed at least substantially in a circular arc or ellipse.   11) Injection plant according to one of claims 8 to 10, characterized in that the transitions between the central zone (152a, 152c) and the marginal zones (152b, 152d) of the guide segment (152) of the valve member (52) are rounded.   12) Injection plant according to claim 1, characterized in that the valve is a high-pressure discharge control valve (23) of a high-pressure fuel pump (10) of a fuel injection plant. fuel.   13) Injection plant according to claim 1, characterized in that the valve is a fuel injector (12) and the injector needle (28) controls at least one ejection port (32).   14) Injection device according to claim 1, characterized in that the valve is a relief valve (80) whose movement of the valve member (82) allows to discharge from time to time the pressure in the chamber working (22) of a high-pressure fuel pump (10) of a fuel injection plant.