WO2008104421A1 - Planar exposure on fuel injectors - Google Patents

Abstract

The invention relates to a fuel injector (10) comprising a holding body (12) and a nozzle body (22) and additional components supplied with fluid. The fuel injector (10) is configured substantially as a screw assembly and includes a nozzle tensioning nut (26). At least one planar exposure (48, 50, 52, 54; 58, 60, 80) is configured on at least one face (28) of the holding body (12) of the fuel injector (10).

Description

 description

title

Area clearance at fuel injectors

State of the art

In previously used fuel injectors holding body, nozzle body, optionally an applicable throttle plate and a valve plate are used. The mentioned components are fixed together with a nozzle retaining nut designed as a union nut as a screw connection. Upon application of the torque to the nozzle lock nut, the introduction of an axially acting biasing force on all components exemplified above follows.

In the normal case arises due to the plan formation of opposing contacting faces of the holding body, throttle plate, valve plate and plan side of the nozzle body when applying the defined tightening torque to the nozzle retaining nut with the application of the defined tightening torque by the generated axial force the required seal.

Fuel injectors are pressurized with high system pressure fuel regardless of whether it is an injector pressurized by a pump nozzle system or a fuel injector pressurized by a high pressure common rail injection system. In such fuel injection systems system pressures of 1600 bar and more prevail, so that components exposed to this system pressure, not least the fuel injector, must be suitably sealed to prevent on the one hand fuel from leaking into the environment and, on the other hand, due to excessive leakage losses, the hydraulic efficiency of such fuel injectors is unduly impaired.

In order to meet the ever increasing demands on the fuel injectors in view of constantly increasing system pressures, an improvement of the seal in Schraubverbund a fuel injector is required. Disclosure of the invention

According to the invention, a fuel injector with a holding body, a nozzle body and a plurality of inserts, such as throttle plate and valve plate, in such a way that at least the front side, which assigns the valve plate of the Kraftstoffinjektorverbundes has at least one surface release, which in contact with the opposite plan side of the valve plate of a maximum surface pressure between these contacting components generates the application of the defined tightening torque on the nozzle retaining nut. The at least one planned surface release minimizes local seating on the end face as well as tilting and increases the robustness of multiple screw connections.

The at least one area exposure is preferably formed on the end face of one of the components to be contacted with one another at a depth of a few tenths of a millimeter, preferably 0.2 millimeters. In this case, the at least one area exposure can be formed both on the end face of the holding body and on the opposite valve plate or on other components which are axially braced against each other within the screw connection. Due to the area exposure, which is preferably formed by the at least one area exposure, preferably at a depth of a few tenths of a millimeter, the pressure on the remaining, raised protruding residual surface at the respective end face at the same axial force, by means of screwing as Bohrvorspannkraft is applied, effectively increased. The at least one surface exposure can be formed in several variants, in which it is desirable to obtain as symmetrical a shape as possible and to shift the resulting area centroid with respect to the at least one area exposure as close as possible to the cylinder axis of the holding body.

In a first embodiment of the inventively proposed to be formed on a contact surface of the holding body, for example, at least one area exposure can at the front, taking into account the hole pattern for pin holes, an actuator chamber bore for receiving an actuator, such as a piezoelectric actuator or a solenoid valve, four Surface exposures are applied in cloverleaf. Taking into account the drilling pattern, ie the course of pin bores, leakage oil bores, actuator chamber bores and high-pressure lines, these circumferential extensions can have between 45 ° and 90 °, these values being able to vary taking into account the courses of the bores mentioned. By the example in the first embodiment advantageously selected arrangement of the surface reliefs in the form of a four-leaf clover a symmetrical arrangement of the surface exposures is achieved, whereby the centroid of the Flächenbeilegungen coincides with the cylinder axis, for example, the holding body. In the arrangement shown in the first embodiment in the form of a four-leaf clover, the pin bores, for example, run outside the surface reliefs in the raised protruding residual surface, so that burr formation does not occur during the production process.

In another advantageous embodiment variant, it is advantageously possible to achieve a butterfly-shaped arrangement of two surface exposures extending, for example, over 170 °. This embodiment variant represents the optimum with respect to the two requirements of the largest possible area exposure on the one hand, the preservation of symmetrical as possible arrangement of the surface exposures on the other hand. According to the second embodiment, the high pressure bores, which are offset by 180 ° to each other, in the raised area outside the two in the form of a butterfly arranged area exposures.

In the two aforementioned advantageous embodiments of the solution on which the invention is based, it is ensured with respect to the surface exposures that the remaining, protruding contact region of the end face, for example of a holding body of another component of the screw connection of a fuel nozzle, has a sufficient residual web width.

Brief description of the drawings

With reference to the drawings, the invention will be described in more detail below.

Show it:

1 shows the view of a fuel injector,

FIG. 2 shows a section through the holding body of the fuel injector in accordance with section line II-II in FIG. 4,

FIG. 3 shows a longitudinal section through the holding body of the fuel injector according to the sectional profile III-III entered in FIG. 4,

FIG. 4 shows a plan view of the end face of the holding body, FIG. 5 shows the plan view of the end face of a holding body of the fuel injector designed according to the invention,

FIG. 6 shows a further embodiment of the design of the end face of the holding body of a fuel substance injector,

Figure 7 shows a further advantageous embodiment of the design of the end face of the holding body of a fuel injector, and

Figure 8 shows an embodiment of the end face of the holding body with a more than 270 ° sweeping area exposure.

embodiments

The illustration according to FIG. 1 shows a fuel injector which consists essentially of a number of components forming a screw together with one another.

The fuel injector 10 shown in Figure 1 comprises a holding body 12 in which an actuator 14 is housed. The actuator 14 accommodated in the holding body 12 may be a piezoactuator as well as a solenoid valve. For energizing the actuator 14, a plug connection is provided in the upper region of the fuel injector 10 shown in FIG.

Furthermore, a coupler module 16 is accommodated in the holding body 12 of the fuel injector 10. The holding body also has an end face 28 with which the holding body 12 contacts an end face 30 of a valve plate 18. Below the valve plate, in which the actuated via the coupler module 16 switching valve is received, there is a throttle plate 20, in which at least one throttle cross-section is formed. Below the throttle plate 20 of the fuel injector 10 is a control chamber, by the pressure relief or pressurization of a preferably needle-shaped injection valve member 24 is actuated. The injection valve member 24 in turn is received in a nozzle body 22. The nozzle body 22, the throttle plate 20, the valve plate 18 and the holding body 12 are screwed together via a nozzle lock nut 26. The nozzle retaining nut 26 is acted upon in the assembly of the above-mentioned components with a defined tightening torque, so that a torque applied to the applied tightening torque taking into account the internal friction in the screw verbünd the fuel injector 10 is initiated. In addition to a defined axial force acting in the axial direction caused by the bias also a seal at the contact surfaces of the individual components of the fuel injector 10 to each other.

The contact surfaces are shown in detail in the illustration of Figure 1 as the first sealing joint 66 between the holding body 12 and the valve plate 18, as a second sealing joint 68 between the valve plate 18 and the throttle plate 20 and as a third sealing joint 70 between the throttle plate 20 and the nozzle body 22.

FIG. 2 shows the section through the holding body 12 of the fuel injector according to FIG. 1 in accordance with the section line II - II in FIG. 4.

From the illustration according to FIG. 2 it can be seen that the holding body 12 has a leakage oil bore 32 in this sectional plane, which traverses the holding body 12 vertically. Above the end face 28 on the underside of the holding body 12 is a thread 34, onto which - as shown in FIG. 1 - the nozzle body 22, the throttle plate 20 and the valve plate 18 receiving nozzle retaining nut 26 is screwed.

FIG. 3 shows a further section through the holding body of the fuel injector according to the sectional profile III-III shown in FIG.

From this sectional view, which lies in front of the longitudinal axis of the holding body 12, it is apparent that the holding body 12 in the upper region comprises a rod filter bore 40 from which a first high-pressure bore 36 and a second high-pressure bore 38 emanate. The high-pressure bores 36 and 38 run essentially parallel to an actuator chamber bore 42. In the actuator chamber 42, as shown in FIG. 1, the actuator 14 can be received, which may be, for example, a piezoactuator.

Also in the illustration according to FIG. 3, the lower front side of the holding body 12 is identified by the reference numeral 28.

FIG. 4 shows a plan view of the end face of the holding body shown in FIGS. 2 and 3 in sections II-II and III-III.

FIG. 4 shows that a plurality of bores open at the end face 28 of the holding body 12. On the one hand opens on the end face 28 of the holding body 12, the Aktorraumbohrung 42, in which the actuator 14 shown schematically in Figure 1 is installed. In addition, open in the region of a raised surface 46, which, for example, the contact surface to the end face 30 of the valve plate 18, pin holes 44 for the correct orientation of the holding body 12 with respect to the valve plate 18 and its connection bores.

From the plan view of Figure 4 also shows that in the raised surface 46 on the end face 28 of the holding body 12, the two shown in Figure 3 in section high pressure bores 36 and 38, offset with respect to each other by 180 °. Finally, in the raised surface of the end face 28 of the holding body 12, the leakage oil bore 32 shown in the section along FIG. 2 opens, via which the controlled amount or return flow is fed back into the low-pressure region of the fuel injection system into which the fuel injector 10 is integrated.

In the representation according to FIG. 4, the raised surface 46 represents the contact surface on which the holding body 12, in the screw connection as shown in FIG. 1, contacts the end face 30 of the valve plate 18.

FIG. 5 shows a first embodiment of the design of the end face of the holding body proposed according to the invention.

The representation according to FIG. 5 shows that a plurality of exposures of 48, 50, 52, 54 are formed on the end face 28. As can be seen from FIG. 5, the exposures 48, 50, 52, 54 lie around the actuator bore 42 in the shape of a cloverleaf. The four local exposure regions 48, 50, 52, 54 shown in the embodiment according to FIG. 5 are arranged in the form of a four-leaf clover. The four area exposures have a circumferential extent of 65 ° with respect to the first exposure area 48 and the second exposure area 50, 90 ° with respect to the third exposure area 52, and 45 ° with respect to the fourth exposure area 54 The minimum web width 56 in the region of at least one exposure is so dimensioned that when screwing the screw assembly of the fuel injector 10 according to the illustration in Figure 1 to none local setting or Verkippungserscheinungen comes and a proper installation of the fuel injector 10 and a proper introduction of the axial force is ensured in the screw according to the fuel injector 10 of Figure 1.

The arrangement of the exposure regions 48 to 54 according to the first embodiment shown in FIG. 5 ensures that a centroid 62 of the exposure regions 48 to 54 coincides with the axis of the holding body 12. From the illustration according to FIG. 5, it can also be seen that the two are opposite each other by approximately 180 °. lying pin holes 44 in the remaining contact surface 64 open. This ensures that the pin bores 44 are not cut in the creation of the exposure areas 48 to 54. This also eliminates burring in the context of the pin bore 44, which is highly undesirable. The exposure areas 48, 50, 52 and 54 arranged in the shape of a cloverleaf in FIG. 5 are introduced into the end face 28 of the holding body 12 at a depth of only a few tenths of a millimeter. Preferably, the depth at which the exposure areas 48, 50, 52, 54 are formed is only 0.2 millimeters.

From the illustration according to FIG. 6, a further advantageous embodiment of the design of the end face of the holding body of the fuel injector emerges.

FIG. 6 shows that two approximately symmetrically opposite exposure areas, namely the fifth exposure area 58 and the sixth exposure area 60 are formed on the end face 28 of the holding body 12, each of which covers an angle of approximately 170 °. The two opposing exposure areas 58 and 60 represent a particularly advantageous embodiment of the invention proposed design of the end face 28 of the holding body 12. The requirements on the one hand, the largest possible surface release and on the other hand maintain a symmetrical arrangement thereof, by the in FIG illustrated embodiment and design of the fifth release area 58 and the sixth exposure area 60 in an optimal manner. The center of gravity 62 resulting from the two exposure areas 58 and 60 coincides with the axis of the holding body 12 of the fuel injector 10 as shown in FIG. From the illustration according to FIG. 6, it can be seen that even in accordance with this embodiment of the design of the end face 28 of the holding body 12 proposed in accordance with the invention, a sufficient web width 56 remains in the area of the fifth exposure area 58 and the sixth free area 60, which can be tilted or set locally during the screwing of the holding body 12 in the context of the screw assembly of the fuel injector 10 shown in Figure 1 effectively avoids.

The illustration according to FIG. 6 also shows that, in contrast to the embodiment according to FIG. 5, the pin bores 44, which run opposite one another, open both in the exposure areas 58 and 60 and partly in the remaining contact area 64.

Analogously to the illustration according to FIG. 5, the two high-pressure bores 36 and 38, which are offset by 180 ° in the holding body 12, open in the remaining contact surface 64 on the end face 28 of the holding body 12. The mouth of the leakage oil bore 32 in turn opens into the sixth exposure region 60, which extends at the end face 28 of the holding body 12 at an angle of approximately 170 °.

In the two embodiments shown in FIGS. 5 and 6 of the concept underlying the invention, it is ensured that the remaining contact surface 64 at the

End face 28 of the holding body 12 has a minimum web width 56, which ensures that in the manufacture of Schraubverbundes, i. when applying the defined tightening torque to the nozzle retaining nut 26, no local setting or tilting of one of the components contained in the screw, in this case the holding body 12, occurs.

FIG. 7 shows a further embodiment of the design of the end face of the holding body.

From the illustration according to FIG. 7, it can be seen that according to this embodiment, surface exposures are integrated in the end face 28 of the holding body 12. These are according to this embodiment, two fourth exposure areas 54, which cover an angle between 30 ° and 35 ° of the end face 28, and a fifth exposure area 58, at an angle between 150 ° and 170 ° of the end face 28 to the valve plate 18th is trained. Analogous to the embodiments described above according to FIGS. 5 and 6, a remaining minimum web width 56 is of the order of a few millimeters, so that tilting or the occurrence of settling phenomena occurs when the valve plate 18 and the exposed surface 28 of the holding body contact 12 is omitted.

In the illustration according to FIG. 7, a different orientation of the high-pressure bores 36, 38, the leakage oil bore 32 and the pin bores 44 is present in comparison with the embodiments according to FIGS. 5 and 6, which however is irrelevant.

Finally, FIG. 8 shows a further embodiment of an area exposure 80, which sweeps over an angle of 320 ° in the end face 28 of the holding body 12 of the fuel injector 10. According to the surface exposure 80, the pin bores 44 and the leakage bore 32 extend within the recessed area, ie, are deeper than the remaining, raised projecting contact surface 64 on the end face 28 to the valve plate 18. Only the first high-pressure bore 36 and the second high-pressure bore 38 extend through the remaining Contact surface 64, only the pin holes 44 are truncated, ie lie on the one hand with a diameter range within the seventh exposure range 80, which is lower by a few tenths of a millimeter in the plane of FIG 8, as the Ben over this protruding remaining contact surface 64. Also according to the embodiment in Figure 8, the minimum web width is indicated by reference numeral 56.

Claims

claims 1. fuel injector (10) with a holding body (12) and a nozzle body (22) and other fluid acted components forming a screw verbünd including a nozzle retaining nut (26), characterized in that at least at one end face (28) of the holding body (12) at least one area exposure (48, 50, 52, 54; 58, 60, 80) is executed. A fuel injector (10) according to claim 1, characterized in that said at least one area exposure (48, 50, 52, 54, 58, 60, 80) is made at a depth with respect to a remaining contact area (64) of a few tenths of a millimeter is. 3. A fuel injector (10) according to claim 2, characterized in that the at least one area exposure (48, 50, 52, 54; 58, 60, 80) at a depth of preferential 0.02 millimeters on the end face (28) of the holding body (12) is executed. 4. fuel injector (10) according to claim 1, characterized in that on the end face (28) of a valve plate (18) contacting the holding body (12) a number of surface exposures (48, 50, 52, 54) are executed in cloverleaf. 5. fuel injector (10) according to claim 4, characterized in that a leakage oil bore (32) of the holding body (12) in one of the surface exposure regions (48, 50, 52, 54, 80) opens. 6. fuel injector (10) according to claim 4, characterized in that pin bores (44) in the remaining contact surface (64) on the end face (28) of the holding body (12) open. 7. fuel injector (10) according to claim 4, characterized in that the centroid (62) of the surface exposure regions (48, 50, 52, 54) on the end face (28) of the holding body (12) preferably with the axis of the holding body (12) coincides. 8. fuel injector (10) according to claim 1, characterized in that on the end face (28) of the holding body (12) has two oppositely formed in butterfly shape surface exposure regions (58, 60) are executed. 9. fuel injector (10) according to claim 8, characterized in that a fifth surface exposure area (58) and a sixth exposure area (60) each sweep a circumferential angle of about 170 °. 10. Fuel injector (10) according to claim 8, characterized in that the centroid (62) of the fifth surface exposure area (58) and the sixth exposure area (60) coincides with the axis of the holding body (12). 11. A fuel injector (10) according to claim 4, characterized in that the first and the second exposure area (48, 50) has a circumferential angle of about 65 °, the third Exposure area (52) covers a circumferential angle of about 90 ° and the fourth exposure area (54) covers a circumferential angle of 45 °. 12. Fuel injector (10) according to claims 4 and 8, characterized in that the remaining contact surface (64) on the end face (28) of the holding body (12) has a minimum web width (56) between 1 and 5 millimeters, preferably 3 millimeters and most preferably 1 millimeter.