EP1528251A1 - Injector having structures for limiting changes of opening characteristics due to wear - Google Patents

Abstract

The injector (12) has a nozzle needle (20) with a conical seat section, and a nozzle body (24) in which the needle axially moves and which has a conical locating face (26) for the seat section of the nozzle needle. A part of the seat section forms a sealing face lying against the conical locating face when the injector is closed. A number (64,84) of encompassing slots (66,68,70,72,86,88,90,92,94) are arranged on at least one side (31,33) of the seat section, and may be on the side facing the injector pressure chamber or on the side facing the injection orifice.

Description

State of the art

The invention relates to an injector with a nozzle needle, which has a conical seating area, and with a Nozzle body in which the nozzle needle is axially movable and a conical contact surface for the seating area , wherein a portion of the seating area at closed injector one on the conical contact surface resting sealing surface forms, one on a first Side of the seating area arranged pressure chamber of at least one on a second side of the seating area arranged injection port separates, and with at least a circumferential groove in the nozzle body or the Nozzle needle on at least one side of the seating area.

Such an injector is known from DE 101 22 503 A1. Basically, in such an injector is the Problem that the position of the sealing surface relative to the Cone of the nozzle body and relative to the cone of the Can change nozzle needle. Such a change comes e.g. by the fact that the nozzle needle due to wear incorporated into the nozzle body. Being on a conical Seating area, she wanders while incorporating the Nozzle needle in the nozzle body further outward. As a result is the remaining outside the sealing surface hydraulic effective residual surface of the nozzle needle reduced. This results the hydraulic effectiveness of the residual surface a prevailing in the pressure chamber pressure on the Remaining area acts and creates a compressive force, the like is directed that they are of sufficient size the Nozzle needle from the conical contact surface of the nozzle body lifts and thus opens the injector.

Wear-related changes of the hydraulically effective Rest area thus influence a relation between one Opening force and pressure in the pressure chamber. she thus also influence the time course of a Opening of the injector in a controlled Closing force change. By one on the pressure chamber side the seating area arranged circumferential groove in the Nozzle body or nozzle needle becomes a lateral distance generated between the nozzle needle and the nozzle body. Of the lateral spacing prevents the formation of a sealing edge or a sealing surface in the region of the circumferential groove and thus limits a change in the hydraulically effective Area.

This is from the aforementioned DE 101 22 503 A1 known for this purpose a single, relatively wide groove on a pressure chamber side of the sealing surface provides. In addition, this font sees another Groove in the nozzle needle in front, on the second side of the Seating area is arranged radially circumferentially. This groove has the following function. When new, the difference Opening angle of the conical seating area of the nozzle needle and the conical contact surface in the nozzle body slightly on the order of one to three degrees, wherein the conical seating area of the nozzle needle a has a duller angle. As a result, a forms circumferential sealing edge or sealing surface on the second Side of the conical seating area. Below the conical seating area has the nozzle needle one Cone angle, which is even duller than the angle of the conical seating area. Above the conical Seating area, the nozzle needle has an opening angle the sharpener is the angle of the conical seating area.

As long as the angles of the conical contact surface and the conical seating area differ from each other the conical seating area has a defined share of the Opening force. But as soon as wear a largely parallel arrangement of conical seating area and conical contact surface, provides the conical Seating area only when lifting the nozzle needle from the Sealing surface contributing to the opening pressure, its amount but is subject to undefined fluctuations.

Such undefined fluctuations also influence the relation between a pressure in the pressure chamber and an opening pressure and the opening course of the injector negative. By on the second side of the conical Seating area circumferential groove, the training is parallel Surfaces on the nozzle needle and the conical contact surface prevents the nozzle body in the groove. To this Way, at least the extent of the undesirable Fluctuations limited.

It has been shown that injectors with the described radial circumferential grooves a good constancy of temporal Course of injector openings over the life of the Injectors show. The described injectors are especially in storage injection systems for Internal combustion engines with direct injection of Fuel used in combustion chambers of internal combustion engines. Especially with such an application, it is desirable that the life of the injectors at least as long as the life of the rest Components of the internal combustion engine.

Against this background, the object is the invention in the specification of an injector with a further improved Lifetime and reproducibility of the opening behavior over the life.

This task is at an injector of the beginning mentioned type solved by a plurality of circumferential grooves, arranged on at least one side of the seating area are.

It has been shown that such a multitude of peripheral Grooves occur when the injector is closed Impact of the nozzle needle on the conical contact surface Much better attenuates than this with only one groove one side of the seating area would be the case. By the improved damping will increase the life of the injector and the reproducibility of its opening behavior essential improves, so that the object of the invention completely is solved.

It is preferable that the plurality of circumferential grooves the first, the pressure chamber facing side of Sealing area is arranged.

By this measure, the damping properties significantly improved. When incorporating the valve needle in get the valve body due to wear too Edges of the grooves with the conical contact surface of the Nozzle body contact and thus contribute to the contact pattern closed injector at. This will wear out further reduced. In addition, the wear-reducing effect The fact that a multitude of small grooves is the Fuel volume between the nozzle needle and the Enlarge valve body only comparatively slightly, while a single large groove that volume of fuel comparatively greatly enlarged.

It has been shown that a strong enlargement of this Fuel volume, the damping properties negative impaired. This may be due to this causes that when closing the injector occurring pressure pulse too fast by the enlarged Volume is reduced. Replacing a single large one Groove caused by a multiplicity of small grooves on the one hand a reduction in wear on an improvement the attenuation and on the other hand, a reduction in wear over Posts by Nutkanten to the contact pattern of the closed Injector. Here, under the contact pattern, the sum of the Contact surfaces between the conical contact surface of the Nozzle body and the nozzle needle understood.

It is also preferable that the plurality of circumferential grooves one of the injection port facing the second side of the Sealing area arranged.

Again, has the replacement of a large groove by a Variety of smaller grooves the advantage of that one Fuel volume between the nozzle needle and the Nozzle body is reduced. This will be the Damping properties improved. As a further advantage is an improvement in exhaust emissions, the caused by the fact that with the injector closed less fuel through the at least one Injection opening can be blown out.

Another embodiment is characterized in that depending on a plurality of circumferential grooves on one of Pressure chamber facing first side and one of the Injection opening facing the second side of the Sealing area is arranged.

This embodiment combines the above Advantages and thus ensures good damping in Compound with an improvement in exhaust emissions and the wear behavior.

A further preferred embodiment is characterized out that the grooves on the first side by at least one axial groove hydraulically with the pressure chamber be connected and / or circulating on the second side Grooves hydraulically with the at least one injection port get connected.

By the hydraulic connection on the first page Be the advantages mentioned above without a Reduction of the hydraulically effective area, at the one opening pressure attacks reached. Through the axial grooves also arises within the possibly on Valve body adjacent grooves of the pressure in the pressure chamber and generates opening force contributions in the grooves. In addition, the axial grooves allow for closing the injector a pressure relief of the circulating Radial grooves, what else during the closing process if necessary prevents opening force peaks occurring and thus to contributes to a defined closing of the injector.

It is preferred that at least one axial groove in the Nozzle needle is arranged. Alternatively or additionally at least one axial groove also in the conical contact surface be arranged of the nozzle body.

A arranged in the nozzle needle axial groove can be easier and therefore cheaper to manufacture than one in arranged the conical contact surface of the nozzle body Axial groove. The disadvantage could be such an arrangement however in connection with different surface hardnesses the conical contact surface of the nozzle body, in the Usually softer than the seating area of the valve needle, impact. In an arrangement of the longitudinal grooves in the Nozzle needle has been shown to be a possible Rotary movement of the nozzle needle to its Längsache to a Milling action on the conical contact surface of the nozzle body can lead.

Such a milling effect is due to the fact that the Edges of the axial grooves in a hard nozzle needle rather like Cutting edges of a router act as if in the comparatively softer material of the nozzle body are arranged over which, if necessary, the harder Turn the nozzle needle away. Regardless of where the axial grooves are arranged, they cause a throttling action, the constructive by length and cross section of the axial grooves is determinable. By this constructive determination can Pressure buildup and pressure reduction gradient constructive being influenced, being usually very steep Pressure gradients are preferred, as by achieved comparatively large cross-sections of the axial grooves become.

It is further preferred that said plurality of 2 to 10 Includes grooves.

This range of numbers of grooves has proven to be special advantageous with regard to a realization of the above highlighted advantages.

Further, it is preferable that the plurality of grooves in one conical recess of the nozzle needle are arranged with the conical contact surface an angle between zero and three degrees, and away from the seating area starting opens.

Also in this embodiment is a shape, their benefits are in view of the above benefits has shown empirically.

This applies analogously to an embodiment of the injector, the is characterized in that a wall of a groove and the conical contact surface of the nozzle body at an angle of eighty to one hundred degrees collide. It has become the angle of ninety degrees is particularly advantageous exposed.

Further advantages will be apparent from the description and the attached figures. It is understood that the above mentioned and the features to be explained below not only in the specified combination, but also in other combinations or in isolation are usable without the scope of the present invention to leave.

drawings

Fig. 1

schematisch ein Speichereinspritzsystem mit einem bekannten Injektor;

Fig. 2

Verläufe von Drücken an verschiedenen Stellen des Injektors aus der Figur 1 über der Zeit;

Fig. 3

einen resultierenden zeitlichen Verlauf einer Öffnung des Injektors;

Fig. 4

einen mit einem Ventilkörper zusammenwirkenden Abschnitt einer Düsennadel eines erfindungsgemäßen Injektors; und

Fig. 5

einen Querschnitt von Nuten, die radial umlaufend in einer Düsennadel angeordnet sind.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

Fig. 1

schematically a storage injection system with a known injector;

Fig. 2

Curves of pressures at various points of the injector of Figure 1 over time;

Fig. 3

a resulting time course of an opening of the injector;

Fig. 4

a cooperating with a valve body portion of a nozzle needle of an injector according to the invention; and

Fig. 5

a cross section of grooves, which are arranged radially circumferentially in a nozzle needle.

Figure 1 shows a storage injection system 10 with a Injector 12, the fuel from a high-pressure accumulator 14th receives. The fuel pressure in the high-pressure accumulator 14 is generated by a high-pressure pump 16, the fuel off a low-pressure system is supplied, the at least one Fuel tank 18 includes. In so-called common rail accumulator injection systems the applicant is the of the High pressure pump 16 provided pressure in the Magnitude of up to 1600 bar. In the injector 12 is axially movable, a nozzle needle 20 is guided on a Injection-side end of a conical seating area 22nd having. The nozzle needle 20 is from a nozzle body 24th received, which has a conical contact surface 26 for the conical seating area 22 of the nozzle needle possesses.

When the injector 12 is closed is a portion of the conical seat portion 22 on the conical bearing surface 26th and forms there a sealing surface or sealing edge 28th In this case, a new-type injector 12 is formed First, a sealing edge 28, which increases with increasing Operating time of the injector 12 gradually to a Widened sealing surface 28. The broadening results as a result of setting or incorporating the nozzle needle 20 in the conical contact surface 26 of the nozzle body 24. Im closed state separates the sealing edge or Sealing surface 28 a pressure chamber 30 of a Injection opening 32. The pressure chamber is thus on a first side 31 of the conical seating area 22 and the Injection port 32 is on a second side 33 of the conical seat portion 22 is arranged. In the presentation Figure 1 is the conical seating area 22 on his first side 31 bounded by a groove 34 which in the Nozzle needle 20 is arranged radially circumferentially.

The pressure chamber 30 is supplied via an inlet 36 with fuel filled from the high-pressure accumulator 14 and is therefore below the pressure that prevails in the high-pressure accumulator 14. This pressure calls on a hydraulically active surface 38 a force that is directed to be at sufficiently high amount of the nozzle needle 20 against closing acting forces of the conical contact surface 26 lifts and opens the injector in this way. When open Injector will fuel over the inlet 36, the Pressure chamber 30 and the injection port 32, for example in a combustion chamber, not shown a Internal combustion engine, in particular a diesel engine, injected.

As a closing force acts essentially a compressive force in a control chamber 40, which via an inlet throttle 42 with the Inlet 36 is connected and in which as a result also adjusts the pressure prevailing in the high-pressure accumulator 14 pressure. An additional closing force component can by a elastic element 44, for example a steel spring, be applied. Opening and closing the injector 12 takes place in a controlled manner by varying the pressure in the control room. In this case, a pressure build-up takes place via the inlet throttle 42 with the control valve 48 closed. Inlet throttle 42 and an outlet throttle 46 are so designed that with open control valve 48 a Pressure reduction in the control room 40 takes place. The control valve 48 is controlled by a controller 52. At high pressure in the control room 40, the closing forces and outweigh sinking pressure in the control chamber 40, the injector then opens, when at the hydraulically active surface 38th attacking opening forces greater than the remaining Closing forces are.

In the figure 2, the curve 54 denotes a course of the Pressure in the control room 40 at an opening and subsequent Close the control valve 48. The control valve 48 opens at a time t_0. As a result, the pressure drops in the Control room 40 and goes through a value p_1. This Pressure value p_1 corresponds to a new-type injector 12 a pressure in which a balance of power between the Closing forces and opening forces at the nozzle needle 20 attack, prevails. Dominate the further decline the opening forces caused by the pressure in the pressure chamber 30 are generated on the hydraulically active surface 38. As a result, the injector 12 by lifting the nozzle needle 20 of the conical contact surface 26 of the nozzle body 24th open.

The opening of the valve takes place at time t_1 and is graphically illustrated in the figure 3, the time course of the opening of the injector 12, for example, the time course 56 of a distance between nozzle needle 20 and conical bearing surface 26, represents. As a result of the dynamic flow through the Pressure chamber 30 with the injector 12 open also turns in the pressure chamber 30, a reduced pressure 58 at an opened injector 12 a. When closing the Control valve 48 at a time t_3 is the Fuel flow through the injector 12 is interrupted and it a pressure oscillation 60 arises in the pressure chamber 30 and in the control room 40 a. By closing the Control valve 48 initially increases the pressure in the control room 40th so that the closing force dominates again and the Nozzle needle 20 on the conical contact surface 26 of the Nozzle body 24 presses.

In particular, the pressure oscillation 60 ensures a strong mechanical load on the sealing surface 28, which with increasing operating time of the injector 12 to a Broadening of the sealing surface 28 and to a setting of Nozzle needle 20 leads. In the illustration of Figure 1 a setting of the nozzle needle 20 means that the Nozzle needle 20 deeper into the nozzle body 24 incorporates. When As a result, the hydraulically effective surface 38 decreases and with that also at a certain pressure in the Pressure chamber 30 generated opening force.

As a result, the remaining opening force only then from the pressure 54 in the control room 40th resulting closing force exceeds when the pressure in Control chamber 40 has fallen to a pressure value p_2. The means that with increasing setting of the nozzle needle 20 a late opening and also an earlier closing of the Injector 12 takes place, which in the figure 3 by the dashed curve 62 is shown. This designates the time t_2 the timing of the opening of the injector 12 when passing through the pressure value p_2 in the control room 40. As already described above, the groove limits 34 the shrinkage of the hydraulically active surface 38th

FIG. 4 shows an embodiment of a injector according to the invention a section of a Nozzle needle 20, which cooperates with a nozzle body 24. The embodiment according to the figure 4 is characterized a plurality 64 of grooves 66, 68, 70, 72 made on a first side 31 of the conical seating area 22 of FIG Nozzle needle 20 are arranged. In that, instead of one single large groove a plurality 64 smaller grooves 66, 68, 70, 72 is provided, a volume of a wedge-shaped gap 74 through the grooves only slightly increased. As mentioned earlier, this has an improvement in the damping properties result.

When the conical seating area 22 becomes very long Operating duration of the injector 12 completely into the nozzle body 24 has been incorporated, successive edges 67, 69, 71 the grooves 66, 68, 70, 72 in contact with the conical Contact surface 26 of the nozzle body 24 come and so in the Contact pattern of the sealing surface 28 are integrated. The edges 67, 69, 71 are caught in a sense in the conical contact surface 26 and provide for improved Sealing even with very long operating periods of Injektors 12. This is the hydraulically effective area 38, which was explained in the figure 1, not enlarged, because of an axial groove 76 in the nozzle needle 20 and / or an axial groove 78 in the nozzle body 24 is a hydraulic Connection of the interior of each groove to the pressure chamber 30th will be produced.

Thereby, the interior of the grooves 66, 68, 70, 72 for depressurizes the case that the edges 67, 69, 71 said grooves in the conical contact surface 26th have hooked and thus the liquid volume in the concerned groove the direct way over the wedge-shaped Slit 74 have blocked to the pressure chamber 30. In the figure 4 are alternative routes 80 and 82 through the axial grooves 76 and 78 drawn on the pressure peaks when closing an already heavily worn injector 12 degraded can be. Alternatively or in addition to the plurality 64 of grooves 66, 68, 70 and 72 on a first side 31 of FIG Nozzle needle 20 may also have another plurality 84 of grooves 86, 88, 90, 92 on a second side 33 of the conical Seating area 22 of the nozzle needle 20 may be arranged.

To a pressure relief of these grooves 86, 88, 90, 92 also in severely worn state of the injector 12 too ensure axial grooves 96 are also in the Nozzle needle 20 or axial grooves 98 in the nozzle body 24th intended. If several axial grooves are provided, be these preferably distributed symmetrically over the circumference. In particular, the plurality 84 of grooves 86, 88, 90, 92, the on the second side 33 of the conical seating area 22 can be arranged in a conical recess 100th can be generated, which has an angle 102 of zero to three degrees with the conical bearing surface 26 of the nozzle body 24th forms.

Figure 5 shows a preferred property of the radial circumferential grooves. These are preferably made a wall 104 of a groove 106 and the conical Abutment surface 26 at an angle of eighty to one hundred Degrees, preferably of ninety degrees, collide. there is the in the figure 5 with the ziff. 106 designated groove representative of all previously mentioned radial circumferential grooves 66 to 72 and 86 to 92.

Claims (9)

An injector (12) having a nozzle needle (20) having a conical seating area (22) and a nozzle body (24) in which the nozzle needle (20) is axially movably guided and which has a conical bearing surface (26) for the seating area (22), wherein a partial region of the seat region (22) with a closed injector (12) on the conical contact surface (26) resting sealing surface (28) which forms a on a first side (31) of the seating area (22) arranged pressure chamber (30) of at least one on a second side (33) of the seating area (22) arranged injection opening (32) separates, and with at least one circumferential groove (66, 68, 70, 72, 86, 88, 90, 92, 94) in the nozzle body (24) or the nozzle needle (20) on at least one side (31, 33) of the seating area (22), characterized by a plurality (64, 84) of circumferential grooves (66, 68, 70, 72, 86, 88 , 90, 92, 94) arranged on at least one side (31, 33) of the seating area (22). Injector (12) according to claim 1, characterized in that the plurality (64, 84) of circumferential grooves (66, 68, 70, 72, 86, 88, 90, 92, 94) on the first, the pressure chamber (30) facing Side (31) of the seat portion (22) is arranged. Injector (12) according to claim 1, characterized in that the plurality (64, 84) of circumferential grooves (66, 68, 70, 72, 86, 88, 90, 92, 94) on a side facing the injection port (32) ( 33) of the seat portion (22) is arranged. Injector (12) according to one of the preceding claims, characterized in that in each case a multiplicity (64, 84) of circumferential grooves (66, 68, 70, 72, 86, 88, 90, 92, 94) on one of the pressure chambers (30). facing first side (31) and one of the injection opening (32) facing the second side (33) of the seat portion (22) is arranged. Injector (12) according to at least one of the preceding claims, characterized by at least one axial groove (76, 78; 96, 98), the grooves (66, 68, 70, 72) encircling the first side (31) hydraulically connected to the pressure chamber ( 30) connects and / or on the second side (33) circumferential grooves (86, 88, 90, 92, 94) hydraulically connected to the at least one injection port (32). Injector (12) according to claim 5, characterized in that an axial groove (76, 96) in the nozzle needle (20) is arranged. Injector (12) according to claim 5 or 6, characterized in that an axial groove (78, 98) in the conical contact surface (26) of the nozzle body (24) is arranged. Injector (12) according to at least one of the preceding claims, characterized by two to ten grooves as a plurality (64, 84) of circumferential grooves. Injector (12) according to at least one of the preceding claims, characterized in that the plurality (64, 84) of grooves (66, 68, 70, 72, 86, 88, 90, 92, 94) in a conical recess (100) the nozzle needle (20) is arranged, which forms with the conical bearing surface (26) forms an angle (102) between zero and three degrees and opens from the seating area (22).
Injector (12) according to at least one of the preceding claims, characterized in that a wall (104) of a groove (106) and the conical bearing surface (26) abut each other at an angle of eighty to one hundred degrees.

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