DE102007018005A1 - injector - Google Patents

Abstract

The invention relates to an injector (1) for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, with a control valve (10) having an axially adjustable valve chamber (9) delimiting the valve sleeve (11) Fuel flow from a control chamber (4) operatively connected to an axially adjustable valve element (2) can be released or blocked by a discharge channel (8) introduced into a valve piece (5) into a low-pressure region (16) of the injector (1), the valve sleeve ( 11) is guided on a guide pin, which is part of the valve piece (5), in which a first and at least one second in the valve chamber (9) opening, evenly distributed in the circumferential direction transverse bores (14, 17) are introduced, wherein the flow channel ( 8) via the first transverse bore (14) is hydraulically connected to the valve chamber (9). According to the invention, it is provided that at least the first transverse bore (14) opening out into the valve chamber (9) is designed as a throttle bore.

Description

State of the art

The The invention relates to an injector for injecting fuel in a combustion chamber of an internal combustion engine, in particular a Common rail injector, according to the preamble of Claim 1.

From the EP 1 612 403 A1 a common rail injector with a pressure compensated in the axial direction control valve (servo valve) is known, by means of which the fuel pressure is variable in a limited by a valve element control chamber. By varying the fuel pressure within the control chamber, the valve element can be adjusted in the axial direction between a closed position and an open position releasing the fuel flow through a nozzle hole arrangement into the combustion chamber of an internal combustion engine. The control valve comprises an axially adjustable, guided on a guide pin valve sleeve which defines a valve chamber radially outward. In these open two opposite, throttle-free transverse bores emanating from a hydraulically connected to the control chamber axial flow channel. The guide pin is integrally formed with a valve piece which rests on a throttle plate which limits the control chamber in the axial direction. The provision of the throttle plate is necessary to limit the flow rate of fuel (control amount) from the control chamber with the control valve open.

Disclosure of the invention

Technical task

Of the Invention is based on the object, an injector with a Propose valve sleeve having control valve, at the number of necessary components is reduced.

Technical solution

These The object is achieved with the features of claim 1. Advantageous developments of the invention are in the dependent claims specified. The scope of the invention also includes all combinations at least two of in the description, the claims and / or the figures specified characteristics.

Of the Invention is based on the idea, at least the first transverse bore, which opens into the valve chamber and over the Drain channel is connected to the valve chamber to run as a throttle bore. about the ratio of the flow area of the outlet throttle and supplying the control chamber with fuel under high pressure Inlet throttle can be the outflow speed of fuel (Control amount) from the control chamber in a hydraulically considered behind the valve space arranged low-pressure region of the injector, which is connected to an injector return set become. Due to the invention can be applied to those in the prior art necessary separate throttle plate are dispensed with.

Theoretically it would be conceivable only a single transverse bore in the Provide valve piece. Especially at very high operating pressures and small guide diameters of the guide pin however, such an unsymmetrical construction is undesirable Component deformation resulting in the friction between the valve sleeve and guide bolts would increase what on the one hand lead to increased wear would and on the other hand more powerful and thus space-consuming actuators for adjusting the valve sleeve would require. For this reason, it is essential to the invention at least one further transverse bore opening into the valve chamber to provide in the valve piece, which in the valve chamber opening out transverse bores evenly distributed in the circumferential direction must be to asymmetric component deformations in the management area to avoid the valve sleeve. If only two transverse bores are provided, so they are with respect to the longitudinal center axis of the guide pin arranged opposite each other. For example three transverse bores opening out into the valve space, so they should be arranged offset by 120 ° to each other become. Under transverse bore in the context of the invention are all To understand in the valve chamber opening holes, the at an angle to the longitudinal center axis of the guide pin run. An orthogonal arrangement to the longitudinal central axis of the guide pin is not necessary and in training the invention even undesirable. By providing at least a further transverse bore and the symmetrical arrangement of Cross holes become unbalanced loads or deformations the valve piece avoided or at least reduced.

to Avoidance of cavitation damage, especially at the control valve seat, is the at least one designed as a throttle bore transverse bore with a radially outer diffuser section provided. For this has the at least one formed as a throttle bore transverse bore preferably a section opening out into the valve space with a larger diameter than the diameter the actual throttle section of the transverse bores.

According to a first alternative of the invention are all in the, in particular as Rin formed Graum trained valve chamber opening transverse bores as throttle bores, each of which is preferably provided with a diffuser section. As a result, the flow velocity in the individual transverse bores can be reduced with positive effects on the wear. The formation of at least two transverse bores as throttle bores, the flow control in the control valve seat area can be favorably influenced, whereby the control of the fuel when opening the valve sleeve and the filling of the annular groove during the closing of the valve sleeve of the control valve is advantageously symmetrical.

According to one second alternative is at least one of the transverse bores, preferably all cross bores except one designed as a throttle bore Cross hole, as from the outside in the valve piece introduced blind hole (s) formed. In other words The trained as blind holes cross holes do not reach up to the flow channel zoom, which cross-bores no fuel line function but only the function of an asymmetrical deformation to minimize the valve piece with guide pins, preferably to prevent.

The Last described embodiment is manufacturing technology Of particular interest, in particular because the tolerances to be met can be larger than when the cross holes would have to be executed as (exact) throttle bores.

In Development of the invention is provided with advantage that all not only in the valve space opening transverse bores are evenly distributed in the circumferential direction, but that all cross bores, d. H. all Longitudinal axes of the transverse bores with the longitudinal center axis of Guide bolt the same angle. However, it is also possible, through a targeted different Angular selection Influence on the component deformation of the valve piece to take in operation. Preferably, the transverse holes close with the longitudinal center axis of the guide pin a from 90 ° different angle.

It has proven to be advantageous when the angle between the longitudinal axis of at least one transverse bore, preferably all transverse bores and the longitudinal center axis of the guide pin from a range between about 10 ° and about 80 ° is selected. Especially advantageous is an angle from a range between about 20 ° and about 70 °, preferably from a narrower angle range between about 30 ° and about 60 °. Of particular advantage it is when the angle is from an angular range between about 40 ° and about 50 ° is selected. Very good results were achieved with an angle of about 45 °.

The oblique arrangement, in particular as a throttle bore Trained transverse bore (s) allows sufficient Diffuser length in the radially outer end region the cross-drilled holes in order to avoid the risk of cavitation damage, in particular at the control valve seat continue to reduce. About that in addition are by the oblique (≠ 90 °) Arrangement of cross bores proven production methods for the production of drain throttles, such as erosion and HE rounding continue to be used.

By Variation of the angular position, in particular as throttle bores trained transverse bores is also an advantageous influence on the Component strength possible.

In Development of the invention, the symmetry of the transverse bores extends not just their symmetrical arrangement in the circumferential direction, but also on the formation of the transverse holes as such. Prefers is an embodiment in which the transverse bores, at least have the same bore diameter in the Ausmündungsbereich. In particular, this is the diameter of the diffuser sections the at least one formed as a throttle bore transverse bore.

From Advantage is an embodiment in which at least the formed as a throttle bore (s) transverse bore (s) in the lower region of the valve chamber discharges from the valve piece. hereby becomes a small distance of the mouth area of the cross holes realized to the valve seat, resulting in a significant reduction the damage volume in favor of the hydraulic reaction time of Injector results.

Out Component strength reasons, it is advantageous if the Outflow channel in the valve piece in the axial direction not is brought up to the valve chamber, but below of the valve space in the at least one designed as a throttle bore Transverse bore passes.

by virtue of the possible abandonment of a throttle plate, the Control chamber in an embodiment of the invention in axial and preferred also limited in the radial direction of the valve piece. The valve piece takes advantage of a Guide function for the valve element, so that in addition to the prior art in addition to a guide sleeve can be waived.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings; these show in:

1 an incomplete representation of an injector with a pressure-balanced in the axial direction control valve,

2 an enlarged detail 1 .

3 an alternatively formed injector with a pressure-balanced in the axial direction control valve and

4 an enlarged detail 3 ,

embodiments the invention

In The figures are the same components and components with the same Function marked with the same reference numerals.

In 1 is a section of an injector designed as a common rail injector 1 shown for fuel. The injector 1 includes a fragmentary illustrated, one or more parts valve element 2 that is adjustable between an open position and a closed position. In its open position gives the valve element 2 the fuel flow from a nozzle hole arrangement not shown in a likewise not shown combustion chamber of an internal combustion engine free.

With an upper end face 3 limits the valve element 2 a control chamber 4 , The control chamber 4 is radially inside a valve piece 5 arranged, which is braced in an axial direction in an injector body, not shown. The valve piece 5 at the same time serves as a guide element for the valve element 2 ,

In the control chamber 4 one opens into the valve piece 5 introduced inlet throttle 6 that the control chamber 4 with fuel from a lower portion of the valve piece 5 surrounding pressure chamber 7 provided. The pressure room 7 is in turn supplied by a fuel supply line, not shown, with high-pressure fuel from a high-pressure fuel storage (also not shown). When the valve element is open 2 (Adjusted in the plane of the drawing to the top axially), the fuel flows out of the pressure chamber 7 through the nozzle hole arrangement in the combustion chamber of the internal combustion engine.

From the control chamber 4 opens in the axial direction in the valve piece 5 introduced drainage channel 8th out. The drainage channel 8th is throttle-free and designed as a blind hole and ends with axial distance to a trained as an annular space valve space 9 a control valve 10 (Servo Valve).

The control valve 10 comprises an axially adjustable valve sleeve 12 in this embodiment, integral with an anchor plate 12 connected is. The anchor plate 12 acts together with a solenoid assembly, not shown, and forms with this an electromagnetic actuator for actuating the valve sleeve 11 ,

The valve sleeve 11 encloses radially outside a guide pin 13 acting as the (only) guide for the valve sleeve 11 serves.

The drainage channel 8th is over an angle (obliquely) to a longitudinal central axis L of the guide pin 13 running first transverse bore 14 with the valve room 9 hydraulically connected. Here is the first transverse bore 14 designed as a throttle bore.

To open the valve element 2 the solenoid assembly, not shown, is energized, whereby the armature plate 12 with the valve sleeve 11 of the control valve 10 is moved in the axial direction in the plane of the drawing upwards. This raises the valve sleeve 11 from her control valve seat 15 at the foot of the one piece with the valve piece 5 trained guide pin 13 and gives the fuel flow in a low pressure area 16 of the injector 1 free, with the low pressure area 16 is connected to an injector return, not shown. The flow cross sections of the inlet throttle 6 and formed as a throttle bore first transverse bore 14 are matched to one another such that when the control valve is open 10 a net outflow of fuel from the control chamber through the drainage channel 8th as well as through the first cross hole 14 and through the valve room 9 through into the low pressure region of the injector results. As a result, the valve element is lowered in the closing direction 2 acting pressure force, so that this lifts off from its valve seat, not shown, and releases the fuel flow into the combustion chamber. To close the valve element 2 , So to end the injection process, the energization of the solenoid assembly is interrupted, whereby the valve sleeve 11 , in particular spring-assisted on its control valve seat 15 is moved and thus the valve space 9 that of a reduced diameter portion of the guide pin 13 is formed, from the low pressure area 16 separates, leaving the pressure in the control chamber 4 through the over the inlet throttle 6 from the pressure room 7 inflowing fuel increases again, with the result that the on the valve element 2 closing force acting in the closing direction increases and the valve element 2 on his not shown Valve seat moves.

How out 1 can be seen, lies the first transverse bore 14 with respect to the longitudinal central axis L, a second transverse bore 17 exactly opposite. As a result, unbalanced loads on the valve piece 5 avoided with advantage.

For the following detailed description of the arrangement of the two transverse bores 14 . 17 is based on the detail magnification according to 2 directed. Out 2 it can be seen that both transverse bores 14 . 17 in the annular valve space 9 the pressure balanced in the axial direction control valve 10 open out. The first transverse bore 14 has a radially inner throttle section 18 with a very small diameter. This is followed by an in the valve chamber 9 opening diffuser section 19 on, which has a larger diameter than the throttle portion 18 ,

The second throttle bore 17 is arranged at the same angle α (about 45 °) to the longitudinal center axis L, as opposed to the longitudinal center axis L opposite first transverse bore 14 , It can be seen that the second transverse bore 17 not designed as a through hole, but as a blind hole, wherein the bore diameter and the bore length of the second transverse bore 17 the diameter and the length of the diffuser section 19 the first transverse bore 14 correspond.

The in the 3 and 4 shown injector 1 corresponds in its basic structure to the in 1 As to the similarities to avoid repetition to the previous description with reference to 1 is referenced. In the following, only the differences to the injector according to 1 explained.

Unlike the injector 1 according to 1 are at the injector 1 according to 3 both cross bores 14 . 17 designed as throttle bores and thus connect the running in the axial direction of the drain passage 8th with the annular valve space 9 and with the control valve open 10 with the low pressure area 16 of the injector 1 , This results in a particularly uniform, symmetrical outflow of fuel from the valve chamber 9 in the low pressure area 16 with open control valve 10 reached.

In 4 is the arrangement of the two opposite transverse bores 14 . 17 according to 3 shown in detail. The two cross holes 14 . 17 are formed not only identically, but also symmetrically with respect to the longitudinal central axis L of the integral with the valve piece 15 trained guide pin 13 arranged. Both cross holes 14 . 17 close with the longitudinal center axis L of the guide pin 13 an angle α of about 45 °. The first transverse bore 14 indicates how the first transverse bore 14 according to the 1 and 2 a radially inner throttle section 18 and an adjoining outer diffuser section 19 on. The same applies to the second transverse bore 17 having a radially inner throttle section 20 and an adjoining outer diffuser section 21 includes.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1612403 A1 [0002]

Claims (10)

Injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common-rail injector, having an axially adjustable valve space and a valve space ( 9 ) limiting valve sleeve ( 11 ) having control valve ( 10 ), with which the fuel flow from a with an axially adjustable valve element ( 2 ) Actively connected control chamber ( 4 ) through a into a valve piece ( 5 ) introduced flow channel ( 8th ) into a low-pressure region ( 16 ) of the injector ( 1 ) is releasable or lockable, wherein the valve sleeve ( 11 ) on a guide pin ( 13 ), the part of the valve piece ( 5 ) into which a first and at least a second into the valve space ( 9 ) opening out, evenly distributed in the circumferential direction transverse bores ( 14 . 17 ) are introduced, wherein the flow channel ( 8th ) over the first transverse bore ( 14 ) hydraulically with the valve space ( 9 ), characterized in that at least the first in the valve space ( 9 ) opening transverse bore ( 14 ) is designed as a throttle bore. Injector according to claim 1, characterized in that the transverse bore (s) formed as a throttle bore (s) ( 14 . 17 ) with a diffuser section ( 19 . 21 ) is / are provided. Injector according to one of claims 1 or 2, characterized in that all transverse bores ( 14 . 17 ) as, in particular identical, throttle bores, in particular each with a diffuser section ( 19 . 21 ), are formed. Injector according to one of claims 1 to 3, characterized in that at least one of the transverse bores ( 14 . 17 ) is formed as a blind hole. Injector according to one of the preceding claims, characterized in that all transverse bores ( 14 . 17 ) with a longitudinal center axis (L) of the guide pin ( 13 ) enclose the same angle (α). Injector according to claim 5, characterized in that that the angle (α) between 10 ° and 80 °, with preferably between 20 ° and 70 °, in particular between 30 ° and 60 °, more preferably between 40 ° and 50 °, more preferably about 45 °. Injector according to one of the preceding claims, characterized in that the transverse bores ( 14 . 17 ) at least in sections, preferably at least in the Ausmündungsbereich, the same bore diameter. Injector according to one of the preceding claims, characterized in that the transverse bores ( 14 . 17 ) in the lower part of the valve chamber ( 9 ) from the valve piece ( 5 ). Injector according to one of the preceding claims, characterized in that the drainage channel ( 8th ) with axial distance to the valve chamber 9 with the first cross hole ( 14 ) connected is. Injector according to one of the preceding claims, characterized in that the valve piece ( 5 ) the control chamber ( 4 ) limited.