DE102008005523A1 - fuel 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 depending on the fuel pressure in a control chamber (11) between a closed position and the fuel flow in the combustion chamber releasing opening position adjustable injection valve element (9), and with a control valve (21) associated with the control chamber (21) with a by means of an actuator (31) relative to a on an injector component (13) arranged control valve seat (28) adjustable control valve element (22) of a Guiding member (33) is guided on its outer circumference. According to the invention, it is provided that the guide component (33) rests with a first centering surface (38) on a second centering surface (39) of the injector component (13).

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 is a common rail injector with a pressure balanced in the axial direction control valve known. By means of the control valve, which has a sleeve-shaped control valve element, the fuel pressure can be influenced within a control chamber bounded on the end side by an injection valve element. By varying the fuel pressure within the control chamber, the injection valve element is adjusted between an open position and a closed position, wherein the injection valve element releases the fuel flow into the combustion chamber of an internal combustion engine in its open position. In the known injector, the sleeve-shaped control valve is guided with its inner circumference on an axial extension of an injector component which passes centrally through the control valve element and on which the control valve seat is also arranged.

It is still out of the DE 10 2006 056 840 A1 an injector is known in which the sleeve-shaped control valve element of a pressure-balanced in the axial direction of the control valve is guided by means of a guide member on its outer periphery. In this case, the guide component is designed as a separate component from the control valve seat having injector component. An advantage of this embodiment is that the control valve seat can be processed independently of the guide for the control valve element. If the described control valve is designed with a control valve seat embodied as a flat seat, the radial positioning of the guide component relative to the injector component plays a subordinate role. However, if the control valve seat is to be designed as a conical seat, then this is problematic, since the guide component during assembly must be centered consuming relative to the Injektor component to produce a coaxiality between the conical seat and outer guide for the control valve element.

Disclosure of the invention

Technical task

Of the Invention is based on the object, an injector with an am Outside circumference guided control valve element to suggest in which automatically with the assembly a good coaxiality between the outer guide and the control valve seat adjusts.

Technical solution

These Task is with an injector with the features of the claim 1 solved. Advantageous developments of the invention are specified in the dependent claims. Fall within the scope of the invention all combinations of at least two of in the description, the claims and / or the figures given characteristics.

Of the Invention is based on the idea, the guide member to arrange directly adjacent to the injector component, wherein the contact surfaces between the guide member and the Injektorbauteil as centering are formed, which are such that the guide member automatically aligns coaxially with the injector component during assembly. This can easily an embodiment the injector realized with designed as a conical seat control valve seat The invention is not limited to such an embodiment is. An educated according to the concept of the invention injector leaves for example, realize with a flat seat. The inventive Injector ensures good accessibility the control valve seat during manufacture and in an optional Coating process and on the other hand, an optimal coaxiality between the outer guide (guide component) and the control valve seat ensured. Put differently, united a trained according to the concept of the invention injector the advantages an injector, in addition to the Injektorbauteil a separate guide member is provided and one Injector, wherein the control valve element on an axial extension guided the Injektorbauteils. To the precision at To further optimize production, it is advantageous if the with the first centering surface of the guide member cooperating second centering surface of the Injektorbauteils and the control valve seat are manufactured in one setting. In addition, it is advantageous in the guide component the guide and the centering surface also in to manufacture a clamping. As a result, the respective plan impact tolerances minimized both components.

In order to simultaneously ensure both a high precision with regard to the coaxiality and the squareness of the control valve seat to the outer guide, an embodiment is advantageous in which the two centering surfaces form a combination of inner cone and outer cone, so either the first centering as Innenkonusfläche and the second centering as an outer cone surface or the first centering surface is formed as an outer cone surface and the second centering surface as an inner cone surface. Preferably, the inner cone angle and the outer cone angle are from a Winkelbe rich selected between about 80 ° and about 160 °, with other cone angles are feasible.

From particular advantage is an embodiment in which the Inner cone angle and the outer cone angle selected be that combination of the two centering surfaces is not self-locking, to automatically align the guide member to allow for the Injektorbauteil during assembly.

In Development of the invention is provided with advantage that the Control valve seat is designed as a conical seat. The provision of a Conical seat as a control valve seat is in the described injector, at the guide member and the Injektorbauteil over each a centering surface abut each other, no problem in Regarding the coaxiality between the control valve seat and outside guide.

The Guide component is suitable with appropriate shape to guide all possible types of control valve elements. However, an embodiment of the invention is particularly preferred Injector, wherein the control valve element is designed such that the control valve is pressure balanced in the axial direction. On this can be achieved in a particularly elegant way by the control valve is designed as a valve sleeve, on the with closed control valve only in radial Direction oriented forces act. In the axial direction acting forces are preferably from one into the control valve element protruding bolt and intercepted by the injector component. It is possible to carry out the bolt in one piece with the injector component, however, an embodiment is preferred in which to facilitate manufacture of the control valve seat of the bolt as is formed by the injector component separate component, preferably in the axial direction upwards on an electromagnet arrangement of a electromagnetic actuator and / or on an injector closure lid supported.

Around sufficient positional stability of the guide component relative to the injector component during operation of the injector Ensuring injectors is one embodiment preferred in which the guide member frontally, d. H. with its centering surface, against the injector component, d. H. against the centering of the Injektorbauteils, pressed is. An embodiment is particularly preferred here, in which the guide component by means of an externally threaded part, in particular with the end face of an externally threaded nut, preferably with an internal thread on an injector body cooperates, in the axial direction of the injector component pressurized becomes.

Around to ensure that the two centering surfaces, at least approximately, completely together come to the plant, an embodiment is preferred in which the outer cone angle and the inner cone angle of Centering surfaces, preferably slightly different are, so that during assembly the centering surfaces first in a radially outer region or in a radially inner area come to rest. By introducing an axial force, for example, with the externally threaded nut described above, then the guide member is overprinted, preferably such that the two centering surfaces, at least approximately, over the entire surface abut each other. For this purpose, the guide component and / or the injector component will be elastic within limits to the desired To participate in deformation without cracking during assembly. To the Bearing surfaces, d. H. the centering surfaces, still defined, at least one of the two centering surfaces, Preferably, both centering surfaces, respectively be divided into at least two areas, for example by the provision of at least one between the surface areas lying annular groove. However, it is also conceivable, one or both centering as each contiguous surface form.

Around with the control valve seat open, an outflow from fuel from the control chamber to an injector return to enable is in the invention with Advantage provided that in the guide member at least one, at least approximately, in the radial direction extending bore is provided as a fuel passage. additionally or alternatively, on the outer circumference of the control valve element and / or on the inner circumference of a guide bore in the guide component at least a Flächenanschliff be provided so that at least an axial passage for exhausting fuel from the control chamber is formed.

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 a section of a common rail injector designed as injector with control valve and

2 : A perspective, sectional view of a guide member and an injector component.

embodiments the invention

In the figures, the same components and components having the same function are the same Reference number marked.

In 1 is an injector designed as a common rail injector 1 for injecting fuel into a combustion chamber of an internal combustion engine. The injector 1 is via a high pressure supply line 2 from a high pressure fuel storage 3 (Rail) with under high pressure, of about 2000 bar in this embodiment, standing fuel, especially diesel or gas supplied. The fuel high-pressure accumulator 3 is from a, in particular designed as a radial piston pump, high-pressure pump 4 with fuel from a low pressure reservoir 5 provided. A low pressure area 6 of the injector 1 is via an injector return 7 with the reservoir 5 hydraulically connected. In the injector return 7 is discharged later to be explained control amount of fuel and the high-pressure pump 4 fed back to the high pressure circuit.

The injector 1 has an injector body 8th in which a one-piece or multi-part injection valve element 9 in the axial direction between an open position and a closed position is adjustable. In its open position are the injection valve element 9 the fuel flow from a nozzle hole arrangement not shown in the combustion chamber of the internal combustion engine free (not shown).

With an upper end side 10 limits the injection valve element 9 a control chamber 11 in a blind hole 12 an injector component 13 is arranged. Alternatively, the control chamber 11 For example, be limited by a sleeve member, in the axial direction of a spring not shown on the Injektorbauteil 13 is spring-loaded.

In the control chamber 11 one opens into the injector component 13 introduced radial inlet throttle 14 that the control chamber 11 with fuel from one of the lower, the control chamber 11 receiving portion of the injector component 13 surrounding pressure chamber 15 (Annulus) supplied. The pressure room 15 in turn is via the high pressure supply line 2 and a supply channel 16 in the injector body 8th with fuel from the high-pressure fuel storage 3 provided. About one of the supply channel 16 branched bore 17 Fuel flows directly to a nozzle chamber, not shown, from which then with the injection valve element open 9 Fuel can flow into the combustion chamber.

The control chamber 11 is with one in the axial direction within the Injektorbauteils 13 running drainage channel 18 with outlet throttle 19 with a valve chamber 20 a control valve 21 (Servo valve) connected. The valve room 20 is in an upper portion radially outwardly of a valve sleeve designed as a control valve element 22 limited and in the axial direction in the plane of the drawing upwards from a multipart bolt 23 (Pen pressure). The bolt 23 is pressurized during operation in the axial direction of the plane of the drawing up, causing the bolt 23 about a investment plate 24 on an injector lid 25 supported by a clamping nut 26 on the injector body 8th is fixed. At the control valve 21 it is a pressure-balanced in the axial direction valve, as on the one piece with an anchor plate 27 trained control valve element 22 with closed control valve 21 no hydraulic opening forces act.

To open the control valve 21 , So to lift the control valve element 22 from his on injector component 13 trained, trained as a conical seat, control valve seat 28 becomes an electromagnet 29 in a holding body 30 an electromagnetic actuator 31 energized, so that in the plane of the drawing below the electromagnet 29 arranged anchor plate 27 and thus the control valve element 22 be moved in the drawing plane in the axial direction upwards. This allows fuel from the valve chamber 20 radially below the control valve element 22 through cross bores 32 in a guide component 33 in the direction of the injector return 7 stream. On his way to injector return 7 the fuel must pass through a centric channel 34 in the holding body 30 flow, that of the bolt 23 is interspersed. The flow cross sections of the outlet throttle are 19 and the inlet throttle 14 coordinated so that a net outflow of fuel from the control chamber 11 results, with the result that the on the front page 10 the injection valve element 9 acting pressure force drops and the injection valve element 9 lifts off from its injection valve element seat, not shown. At the injector return 7 The amount of fuel flowing is the initially mentioned amount of fuel, which then flows through the high-pressure pump 4 the high pressure circuit is supplied again. To stop the injection process is the energization of the electromagnet 29 interrupted, so that the control valve element 22 from one in the channel 34 arranged compression spring 35 back on his on injector component 13 trained control valve seat 28 is moved. Through the through the inlet throttle 14 continue in the control chamber 11 flowing fuel increases the pressure in the control chamber 11 rapidly, causing the injection valve element 9 is moved in the plane of the drawing down on its injector seat, not shown, whereby the flow of fuel is interrupted in the combustion chamber of the internal combustion engine.

How out 1 it can be seen, is the sleeve-shaped control valve element 22 at its outside scope led.

For this purpose, the guide member 33 a sleeve section 36 on, the inner diameter of the outer diameter of the control valve element 22 plus a minimum guide play. The sleeve section 36 goes in its end area in an investment section 37 over, with the cross holes 32 in the transition region between the sleeve section 36 and the investment section 37 are arranged. The investment section 37 has frontally on the injector component 13 facing, in the drawing plane lower, side an inner cone-shaped first centering 38 on, with which the investment section 37 or the guide component 33 over the entire surface on an outer cone-shaped second centering surface 39 rests against the the guide member 33 facing, in the drawing plane upper, front side of the Injektorbauteils 13 is arranged. The cone angle (inner cone angle and outer cone angle) of the two centering surfaces 38 . 39 are identical in the assembled state, but slightly different before assembly, so that in the clamped state of the guide member 33 a full surface area of the centering surfaces 38 . 39 is guaranteed to each other.

To a full-surface system of the guide component 33 on the injector component 13 to ensure is a male thread nut 40 provided with its external thread 41 in engagement with an internal thread 42 of the injector body 8th in an area axially between the anchor plate 27 and the injector component 13 is. By turning the external thread nut 40 relative to the injector body 8th becomes the guiding component 33 with its first centering surface 38 against the second centering surface 39 of the injector component 13 pressed. It can be seen that between the inner circumference of the externally threaded nut 40 and the sleeve section 36 of the guide component 33 an annulus 43 is arranged, over the fuel with open control valve 21 from the valve room 20 in an overlying anchor space 44 and from there into the canal 34 and the injector return 7 can flow.

How to continue 1 is also between an axial extension 45 of the injector component 13 , at the free end of the control valve seat 28 is formed and the radially outside in a lower portion of the valve chamber 20 limited and the inner circumference of the guide member 33 , more precisely the attachment section 37 , another annulus 46 arranged over the cross holes 32 hydraulically with the annulus 43 connected is.

In 2 are in a cut exploded view in perspective, both the guide member 33 as well as the injector component 13 shown. Evident is the previously described axial extension 45 of the injector component 13 , at the end face of the conical seat-shaped control valve seat 28 is trained. On one of the axial process 45 facing away, in the drawing plane lower side has the injector component 13 an annular shoulder 47 on, with it in the axial direction on the injector body 8th supported (see. 1 ).

Radially outward and with axial distance to the axial extension 45 is formed as an annular surface, outer conical second centering 39 of the injector component 13 in the mounted state with the first centering surface 38 of the guide component 33 interacts. How out 2 can be seen, is the second centering surface 39 from two partial surfaces 48 . 49 formed by an intermediate annular groove 50 spaced apart from each other. It is also conceivable, the first centering 38 as a continuous surface or consisting of more than two partial surfaces form.

Furthermore, it is off 2 to recognize that the inner diameter D _{i1 of} the guide member 33 over the largest longitudinal extent of the sleeve section 36 is greater than the inner diameter D _{i2 of} the guide member 33 in the lowermost section of the sleeve section 36 as well as in the investment section 37 so that the guidance of the control valve element 22 exclusively in the sleeve section 36 and not in the radially wider support portion 37 he follows.

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]
• DE 102006056840 A1 [0003]

Claims (11)

Injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, with a function of the fuel pressure in a control chamber ( 11 ) between a closed position and a fuel flow into the combustion chamber releasing opening position adjustable injection valve element ( 9 ), and with one of the control chamber ( 11 ) associated control valve ( 21 ) with one by means of an actuator ( 31 ) relative to an injector component ( 13 ) arranged control valve seat ( 28 ) adjustable control valve element ( 22 ), that of a guide component ( 33 ) is guided on its outer periphery, characterized in that the guide member ( 33 ) with a first centering surface ( 38 ) at a second centering surface ( 39 ) of the injector component ( 13 ) is present. Injector according to claim 1, characterized in that the first centering surface ( 38 ) an inner cone surface and the second centering surface ( 39 ) is an outer cone surface, or that the first centering surface ( 38 ) an outer cone surface and the second centering surface ( 39 ) is an inner cone surface. Injector according to one of the preceding claims, characterized in that the combination of the first centering surface ( 38 ) and second centering surface ( 39 ) is not self-locking. Injector according to one of the preceding claims, characterized in that the control valve seat ( 28 ) is designed as a conical seat. Injector according to one of the preceding claims, characterized in that the control valve ( 21 ) is formed as a pressure balanced in the axial direction valve. Injector according to one of the preceding claims, characterized in that the control valve element ( 22 ) is designed as a valve sleeve. Injector according to one of the preceding claims, characterized in that the guide component ( 33 ), preferably by means of an externally threaded nut ( 40 ), frontally against the injector component ( 13 ) is pressed. Injector according to one of claims 2 to 7, characterized in that the outer cone angle and the inner cone angle before assembly, preferably slightly, are different. Injector according to one of the preceding claims, characterized in that the guide component ( 33 ) and / or the injector component ( 13 ) are elastic, such that the first and the second centering surface ( 38 . 39 ), at least approximately, abut each other over the entire surface. Injector according to one of the preceding claims, characterized in that the first centering surface ( 38 ) and / or the second centering surface ( 39 ) of at least two partial surfaces ( 48 . 49 ) are formed, which preferably via at least one annular groove ( 50 ) are separated from each other. Injector according to one of the preceding claims, characterized in that in the guide component ( 33 ) at least one transverse bore ( 32 ) and / or at least one axial channel radially between the guide component ( 33 ) and the control valve element ( 22 ) are provided by the fuel (s) when the control valve element ( 22 ) in the direction of an injector return ( 7 ) can flow.