EP1952012B1 - Injector - Google Patents

Abstract

Injector (1) has actuator (10), a control chamber (12) fed by control valve (9), which is actuated by the actuator. Injector has a nozzle body with injection opening and a nozzle pin. Pressure reservoir is arranged between control valve and nozzle body. The volume control valve divides the pressure reservoir into high-pressure source connected reservoir part (25) at control chamber side and another reservoir part at nozzle body side.

Description

document GB 2 284 236 A discloses an injection injector with two-part pressure chamber and intermediate closing valve.

The invention is characterized by an injection injector according to claim 1, which is designed in terms of a cost and structurally relatively simple structure and despite this embodiment has only relatively small pressure oscillation amplitudes and also higher switching speeds with the possibility of multiple injections opened as well as working with higher injection pressures.

For the purposes of this objective, a pressure accumulator is integrated in the injection injector via which the nozzle needle is controlled to the injection openings, via a built-in pressure accumulator Mengenbegrenzungsventil whose locking piston preferably additionally serves as a guide element for the optionally hollow control rod from the Control chamber of the control valve starting out by the pressure accumulator extending against the nozzle needle is supported. The piston of the flow control valve is thus used for various functions and also offers the possibility for injection rate progression molding.

In the sense of this last-mentioned function, a configuration proves to be expedient for the blocking piston, which, depending on the adjusting movements of the blocking piston, separates the crossing cross-section between those separated by the blocking piston. pressure accumulator parts and thus also the course of injection.

In terms of design, this can be realized, for example, simply by the diameter of the blocking piston being larger than the diameter of a frontal piston attachment which engages in a section of the control chamber-side pressure storage part and releases corresponding overflow cross sections as a function of the engagement depth. Furthermore, in the solution according to the invention, no structurally complex measures are required for establishing the permissible fuel quantity passing through the blocking piston; rather, this can be achieved by a targeted determination of the leaks, so the games between locking piston and receiving bore and the possible game between control rod and locking piston. In the context of the invention, however, bores, in particular throttle bores, can also be assigned to the blocking piston via which the passage takes place.

Furthermore, the flow control valve can take over the function of a blocking safety valve, which - outside of the operating mode of the internal combustion engine - prevents an inflow of fuel to the cylinder of the internal combustion engine connected to the injector even if the associated injection openings are not completely closed via the nozzle needle. For this purpose, it is provided that the locking piston in its spring-loaded starting position sealing the crossover cross section between the pressure accumulator parts, as long as a threshold defined working pressure is not exceeded and the locking piston is adjusted against the spring force in an open position for the crossover cross section.

Even the integration of the pressure accumulator in the injection injector has a favorable effect on the reduction of pressure oscillations from how they are triggered by the injection. The integration of the flow control valve in the pressure accumulator with corresponding displaceability of the locking piston is to this extent further advantageously noticeable, the locking piston also works in the function of a damping piston. From the reduction of the pressure oscillations, which also results in lower pressure peaks, there is the possibility of increasing the system pressure and higher injection pressures.

In addition, by reducing the pressure oscillations, the possibility for higher switching speeds as well as targeted pulsed injection curves created, according to the invention the control valve is designed in a manner that allows higher switching speeds, using hydrostatic as well as hydrodynamic effects, through which also a damping the control piston movement in the approach results in a respective stop surface as part of a sealing boundary. In conjunction with such a configuration, the advantages of piezo actuators as actuators can be fully exploited, since according to the high switching speed when applying the control piston by the actuator also a correspondingly fast return movement for the control piston can be achieved, but within the scope of the invention also magnetic actuator can be used as actuators.

Fig. 1 und 2

einen Einspritzinjektor, aus Darstellungsgründen aufgeteilt auf einen oberen Teil (Fig. 1) und einen unteren Teil (Fig. 2),

Fig. 3

einen Ausschnitt III aus Fig. 4 in vergrößerter Darstellung, der den Steuerkolben des Steuerventiles im Bereich seines Pilzkopfes zeigt und die Größe der dichtenden Durchmesser zum Durchmesser der Führungsbohrung des Steuerkolbens veranschaulicht,

Fig. 4

eine Ausschnittsvergrößerung IV in Fig. 1, insbesondere zur Verdeutlichung der konstruktiven Ausbildung des Pilzkolbens im Hinblick auf die Unterstützung von Stellbewegungen durch Überströmungseffekte, und

Fig. 5

zur Verbesserung der Übersicht über den Aufbau eines Einspritzinjektors eine Gesamtdarstellung desselben, in einer gegenüber der Ausgestaltung gemäß Fig. 1 und 2 etwas abgewandelten Bauform.

Further details and features of the invention will become apparent from the claims. Furthermore, the invention will be explained below with further details with reference to the drawings. Show it:

Fig. 1 and 2

an injection injector, for illustrative purposes divided into an upper part ( Fig. 1 ) and a lower part ( Fig. 2 )

Fig. 3

a section III from Fig. 4 in an enlarged view, which shows the control piston of the control valve in the region of its mushroom head and illustrates the size of the sealing diameter to the diameter of the guide bore of the control piston,

Fig. 4

a detail enlargement IV in Fig. 1 , in particular to illustrate the structural design of the mushroom piston with respect to the support of actuating movements by overflow effects, and

Fig. 5

to improve the overview of the structure of an injection injector an overall view of the same, in a respect to the embodiment according to Fig. 1 and 2 slightly modified design.

The Fig. 1 and 2 show, in addition to each other, an injection injector 1 according to the invention in its entirety. Combustion chamber side - based on an internal combustion engine, not shown, in the cylinder head of the injection injector 1 is installed injecting the combustion chamber - runs from the injection injector 1 in a nozzle body 2, followed by a conical transition part 4 and an intermediate plate 5, via a clamping nut 3 against an injector 6 are clamped. In the injector 6 is centrally, and open against the nozzle body 2, a pressure accumulator 7 is provided, which is closed at the opposite end to the nozzle body 2 via a closing piece 8, followed by a control valve 9 and this downstream an actuator 10.

The pressure accumulator 7 is centrally penetrated by a control rod 11, which may also be hollow with advantage passes, which runs in a bore of the end piece 8 runs on a control chamber 12, which subsequently to the end piece 8 is covered by a plate 13, followed by the housing 14 of the control valve 9, which in turn is covered by a cover plate 15 which is penetrated by the actuating piston 16 of the actuator 10, which may be formed as a piezo or magnetic actuator, and preferably as shown, is designed as a piezo actuator. About the actuating piston 16 is guided in the housing 14 of the control valve 9 control piston 17 to be acted upon, which is supported in the direction of the actuator 10 via a spring 18 and 18 against the force of the spring 18 via the actuating piston 16 when energized the actuator 10 is adjustable ,

Takes the control piston 17, according to the load by the spring 18, its sealing, upper stop position, the pressure accumulator 7 is connected via the channels 19 and 20 with the control chamber 12, and according to the thus given pressurization of the control chamber 12, the control rod 11 in Direction loaded on the nozzle body 2. If the control piston 17 is displaced by energizing the actuator 10 against the force of the spring 18 and against hydraulic forces in its lower Abdichtlage, the connection of the control chamber 10 is shut off to the accumulator 7 and the control chamber 12 is via the channel 20 and further channels 21, 22 (see Fig. 4 ) is connected to the low pressure side, wherein the connection to the low pressure side is symbolized by the arrow 23.

The pressure accumulator 7 communicates with a high-pressure source, for example a storage tube (common rail), via a channel 24 which opens onto the accumulator 7.

The pressure accumulator 7 is subdivided in the inventive solution into a control valve-side accumulator part 25 and a nozzle-side pressure accumulator part 26, wherein the high-pressure side connecting channel 24 on the control valve side Pressure accumulator part 25 opens and the two pressure storage parts 25, 26 are delimited by a flow control valve 28 against each other. The quantity limiting valve 28 is designed for the fuel throughput during operation of the internal combustion engine with maximum injection quantity and controls the connection between the pressure accumulator parts 25 and 26 when a threshold value lying above the aforementioned flow rate is exceeded.

At its lying below this threshold initial position of the locking piston 29 of the flow control valve 28 is loaded via a support spring 30. This support spring 30 is supported against the injector 6-position support plate 5 and enclosed in the illustrated embodiment by a stop sleeve 31 in its adjacent to the support plate 5 area, wherein the stop sleeve 31 is limited in against the force of the support spring 30 displaced locking piston 29 whose displacement and when plant the locking piston 29 is interrupted on the stop sleeve 31, the passage connection from the pressure accumulator 7 in the direction of the nozzle body 2.

On the support plate 5, a further spring 32 is supported, which operates in the opposite direction to the support spring 30 and the control rod 11 is applied, which in turn is supported against the shaft 33 of a nozzle needle 34 which is guided in a nozzle needle bore 35 of the nozzle body 2 and in its illustrated Closing position to the nozzle body 2 in the end region of the nozzle needle bore 35 lying injection openings 36 absteuert. The nozzle needle 34 is loaded in its closed position in addition to the application of the spring 32 by the hydraulic overweight of the control rod 11 and in the region of its shaft 33 by a stop sleeve 37, through which a positionally secure connection of the nozzle needle 34 to the control rod 11 is made by the control rod 11 protrudes into the stop sleeve 37 and held suitably in this is, wherein the fit is selected such that on the one hand a sealing connection between the stop sleeve 37 and the control rod 11 and the nozzle needle shaft 33 is reached, on the other hand - for assembly - the control rod 11 from the shaft 33 of the nozzle needle 34 can be separated. About the stop sleeve 37, the stroke of the nozzle needle 34 is limited in the opening direction, wherein the stop sleeve 37 is supported in its wegbegrenzenden stop position on the transition part 4.

Starting from the flow control valve 28 is the nozzle-side pressure storage part 26 in open communication with the nozzle needle bore 35, as seen from Fig. 2 can be seen, wherein the nozzle needle 34 in its guide to the nozzle needle bore 35 a flow permitting, in particular polygonal, for example, triangular cross-section, so that in this guide area a free supply of fuel to the seating area of the nozzle needle 34 is given, the pressure-dependent in the over the stop sleeve 37 wegbegrenzte open position is adjustable when the control rod 11 is not pressurized by the control chamber 12 and the control chamber 12 by energizing the actuator 10 and adjustment of the control piston 17 against the force of the spring 18 via the channels 20, 21 and 22 to the low pressure side connected.

The guided over a large part of the length of the injection injector 1, and thus long control rod 11 in the area of their expiring on the control chamber 12 end in the housing 14 sealingly and centering fixed end piece 8 and opposite by their position-fixed connection via the stop sleeve 37 at the Nozzle needle 34, so that the only a few millimeters thick control rod 11, which may optionally also be hollow, both in terms of vibrations and deformations is critical.

The vibration behavior of the injection injector 1 with respect to pressure oscillations is improved by the internal pressure accumulator 7 integrated in the injection injector 1, wherein the accumulator 7 according to the invention advantageously also allows the integration of the flow control valve 28, through which the pressure accumulator 7 into its two pressure accumulator parts 25, 26 is divided and preferably forms a sliding guide for the control rod 11 with its locking piston 29.

The locking piston 29 is with respect to its management tolerances to the injector 6, as well as optionally to the control rod 11 is formed so that in the period between successive injections, an amount of fuel from the control valve side pressure storage part 25 can pass to the nozzle-side pressure storage part 26, which corresponds to the respective regular injection quantity substantially and is below a predetermined threshold. Shown is the formation of the locking piston 29 on its side remote from the support spring 30 side with an end-side piston extension 38 in a diameter of the locking piston 29 in diameter reduced region 39 of the pressure accumulator 7 protrudes. The front-side piston extension 38 offers the possibility of injection rate development by the fact that in the overlap region of the piston extension 38 to the area 39 of the pressure accumulator 7 by tighter fit, by graduated circumferential contours or the like Überströmverhältnisse from pressure accumulator 25 to the pressure accumulator 26 with displacement of the locking piston 29 against the force of Support spring 30 are varied path-dependent. In order to expand the relevant influence possibilities and further in the locked position of the locking piston 29, the leakage connection between the locking piston 29 and the control rod 11 largely To interrupt, it may be expedient to provide the locking piston 29 instead of, or in addition to the piston shoulder 38 with a flexible, in particular pressure-dependent einschnürbaren collar 64.

In order to manage for the control valve 9 with the lowest possible actuating forces, but at the same time to achieve the highest possible switching speeds, the control piston 17, as the Fig. 3 and 4 show, designed as a mushroom piston, that is, with a conically widening head portion 40, which projects beyond the diameter 41 of the shaft 42. The conical head part 40 corresponds on the part of the housing 14 has a conical receptacle 43, and the head part 40 has on the one hand in the direction of the actuator 10 is determined by a sealing edge sealing diameter 44 against the covering cover plate 15 and on the other hand determined by a further sealing edge sealing diameter 45th against the housing 14 in the region of the conical receptacle 43. The sealing diameters 44 and 45 are each larger than the diameter 41 of the shank 42, so that in the direction of the respective sealing abutment pressure-dependent results in a supporting force. In the context of the invention, it proves to be expedient if the sealing diameter 44 and 45 between the head part 40 and the cover plate 15 and the housing side, conical receptacle 43 are interchanged to the arrangement shown to reduce the actuation forces to be applied by the actuator 10 ,

When switching operation with displacement of the control piston 17 from its lower, the high-pressure connection to the control chamber 12 blocking position in the high-pressure compound releasing position, ie at the end of injection by closing the injection ports 36 via the nozzle needle 34, there is a short-circuit connection from the accumulator 7 to the low pressure side (arrow 23) with corresponding flow around the mushroom-shaped Head portion 40, each on the sealing diameter 43 and 44 tapered, mutually inclined and converging in a sealing edge flanks 46, 47; 48, 49. The flanks 46, 47 intersect in the sealing diameter 44, the flanks 48, 49 in the sealing diameter 45. The respective inflow-side edge 46 and 48 adjoins the respective mating surface 50, 51 tapering to the sealing diameter 44 and 45, respectively Position of the control piston 17 from a tapered Durchströmspalt, and depending on the gap height arise - based on the pressure in the stationary medium - pressure deviations, corresponding to the flow rate in the direction of a negative pressure.

This is used in the solution according to the invention and shown to assist the control piston 17 in displacement in the direction of its investment in the upper, sealing diameter 44 supportive; In addition to the force of the spring 18 thus results in a hydrodynamic support effect.

For the purposes of this function, the annular flanks 48, 49 on both sides of the lower, sealing diameter 44 narrow and inclined to the counter surface 51 on the receiving cone 43 only flat, and it is a broader outer edge 46 sought to counter surface 50.

This results in forces in the adjustment; However, it is also clear from the exemplary embodiment that there are far-reaching influencing possibilities on a hydrodynamic basis in order to influence the adjusting movement of the control piston 17 via a corresponding tuning, and in particular to avoid the control piston 17 getting stuck.

Since hydrodynamic actuating forces result in addition to the force applied via the spring 18, a faster pressure build-up is achieved, so that the actuating piston 17 can follow the upward movement of the actuating ram 16 without distortion, and this without any harsher design of the spring 18, the switching valve 9 would require a higher actuating force of the actuator 10.

The solution according to the invention thus leads to a relatively simple injection injector, in which only small pressure oscillations result, in particular due to the integration of an accumulator into the injector, and in which only pressure peaks occur that are slightly above the system pressure, wherein, in addition, low pressure oscillation ranges are achieved , This allows high system pressures.

Advantageous angular sizes in the sense of influencing the adjusting movements of the control piston 17 according to the invention are for the cone angle 52 of the receiving cone 43, for example, 90 °, at a cone angle 53 of lying in the inlet on the lower, sealing diameter 45 edge 48 of about 120 ° and a cone angle 54 of in the course of the lower sealing diameter 55 lying edge 49 of about 80 °, with other angular sizes with a comparable ratio of the angle to each other are within the scope of the invention.

Fig. 5 shows an overall view of an injection injector 60, which in its overall construction largely according to the injection injector 1 Fig. 1 and 2 which is why the relevant reference signs have been adopted and to the description Fig. 1 and 2 is referenced. To deviate from Fig. 1 and 2 the injection injector 60 is provided with an actuator 10 designed as a magnetic actuator. Furthermore, the pressure storage part 26, which is delimited against the pressure storage part 25 via the quantity limiting valve 28, largely within a subsequent to the intermediate plate 5, lying in the transition to the housing 6 insert piece 61 which is sleeve-shaped and which is clamped on the clamping nut 3 together with the nozzle body 2, the transition part 4 and the intermediate plate 5. The actuator piston 29 of the flow control valve 28 supporting support spring 30 is enclosed by the sleeve-shaped insert 61 and is supported against the intermediate plate 5 via a sleeve-shaped piece base from which is designated 62 and, as well as the support spring 30, the control rod 11 surrounds. The stop limit for the locking piston 29 via the insert 61, which has an engaging in the displacement of the locking piston 29 annular collar 63. The annular collar 63 is located on the housing 6 facing the end of the insert piece 61, and the flow control valve 28 is located with its locking piston 29 near the insert 61 facing the end of the housing 6. In the functionalities, the two embodiments of the injection injector 1 or 60 largely, so that reference can be made to the previous statements.

Claims (17)

1. Injector

   ○ having an actuator (10),

   ○ having a control chamber (12) which is supplied via a control valve (9) which is actuated by the actuator (10),

   ○ having a nozzle body (2) with at least one injection opening (36),

   ○ having a nozzle needle (34) which is guided in the nozzle body (2) and which is spring-loaded in the direction of its closed position with respect to the injection opening (36) and which can be adjusted, under the action of pressure, in the direction of its open position with respect to the injection opening,

   ○ having a pressure accumulator (7) which is situated between the control valve (9) and the nozzle body (2),

   ○ having a control rod (11) which extends between the control chamber (12) and the nozzle needle (34) and which extends through the pressure accumulator (7) and which, upon pressurization of the control chamber (12), acts on the nozzle needle (34) in the direction of its closed position, and

   ○ having a flow-limiting valve (28) which divides the pressure accumulator (7) into a control-chamber-side pressure accumulator part (25), which is adjacent to the control valve (9) and which is connected to a highpressure source, and a nozzle-side pressure accumulator part (26) which is open towards the nozzle body (2).
2. Injector according to Claim 1,
   characterized
   in that the flow-limiting valve (28) has a blocking piston (29) which is longitudinally movable in the pressure accumulator (7) and relative to the control rod (11) and which is spring-loaded in the direction of the control-chamber-side pressure accumulator part (25).
3. Injector according to Claim 1 or 2,
   characterized
   in that the blocking piston (29) of the flow-limiting valve (28) has an initial position which is spring-loaded in the direction of the control-chamber-side pressure accumulator part (25) and in which - as a blocking position - the passage cross section between the pressure accumulator parts is blocked in a sealing fashion.
4. Injector according to one of Claims 1 to 3,
   characterized
   in that the blocking piston (29) forms a guide for the control rod (11).
5. Injector according to one of Claims 1 to 4,
   characterized
   in that the blocking piston (29) can be moved, counter to its loading by means of a support spring (30), into a blocking position.
6. Injector according to one of Claims 1 to 5,
   characterized
   in that the diameter of the blocking piston (29) is greater than the diameter of an end-side piston extension (38) which engages, in particular with a fit, into a section of the control-chamber-side pressure accumulator part.
7. Injector according to one of the preceding claims,
   characterized
   in that the spring (32) which loads the nozzle needle (34) in the direction of its closed position and the support spring (30) which supports the blocking piston (29) of the flow-limiting valve (28) in the opposite direction are supported against an intermediate plate (5) which is fixed with respect to the housing.
8. Injector according to one of the preceding claims,
   characterized
   in that the control rod (11) is connected to the nozzle needle (34) in a positionally fixed manner.
9. Injector according to one of Claims 1 to 7,
   characterized
   in that the control rod (11) is of hollow design and is supported loosely, so as to be laterally movable, on the shank (33) of the nozzle needle (34).
10. Injector according to Claim 8,
    characterized
    in that the control rod (11) is fixed to a shank (33) of the nozzle needle (34) by means of a stop sleeve (37) which limits the opening travel of the nozzle needle (34).
11. Injector according to Claim 8 or 10,
    characterized
    in that the control rod (11) is detachably fixed in the stop sleeve (37) with a tight fit.
12. Injector according to one of the preceding claims,
    characterized
    in that the control valve (9) is embodied as a 3/2 directional control valve whose control piston (17) is spring loaded in the direction of its actuating position which opens up the connection from the pressure accumulator (7) to the control chamber (12).
13. Injector according to Claim 12,
    characterized
    in that the control piston (14) of the control valve (9) can be acted on, by means of the actuator (10), in the direction of its position in which it blocks against the pressure accumulator.
14. Injector according to Claim 12 or 13,
    characterized
    in that the control piston (14) of the control valve (9) is embodied as a mushroom-shaped piston which, in its blocking position, has a sealing diameter (44, 45) which differs from the diameter (45) of the holding guide bore.
15. Injector according to Claim 14,
    characterized
    in that the sealing diameters (44, 45) of the control piston (17) are greater than the diameter (41) of the guide bore which holds the control piston (17).
16. Injector according to one of Claims 12 to 15,
    characterized
    in that the control piston (17) is embodied as a mushroom-shaped piston which forms, tapering towards the edge, a flank (46) of a sealing gap which tapers in a wedge-shaped fashion in the overflow direction towards the respective sealing diameter (44).
17. Injector according to one of the preceding claims,
    characterized
    in that the blocking piston (29) is sealingly connected to the control rod (11) by means of a flexible collar (64) which can be constricted in a pressure-dependent fashion.

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