DE102007044356A1 - injector - Google Patents

Abstract

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, with a controllable between a closed position and a fuel flow releasing opening position injection valve element (13), dement (31) having control valve (32) controllable wherein the control valve element (31) cooperates with a control valve seat (34) arranged on a component (14). According to the invention, it is provided that a pressure pin (43) enclosed by the control valve element (31) and separate from the component (14) is provided, and that the control valve seat (32) is designed as an outer cone.

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, the fuel pressure can be influenced within a limited by an injection valve element control chamber. 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. The control valve has an axially adjustable by means of an electromagnetic actuator, sleeve-shaped control valve member which cooperates with a control valve seat. The control valve seat is formed on a plate member from which extends integrally formed therewith a guide pin in the axial direction and passes through the sleeve-shaped control valve element. A disadvantage of the known injector is that the arranged at the foot of the guide pin control valve seat is difficult to produce due to its poor accessibility. In addition, it may come due to the high fuel pressure in the fuel passage in the guide pin to strength problems, so that a comparatively larger minimum diameter of the guide pin can not be exceeded, which in turn has a negative effect on the size of the required space.

Disclosure of the invention

Technical task

Of the Invention is based on the object, an injector with a control valve to propose, whose control valve seat is easily manufacturable, and in the strength problems, even at low control valve seat diameters be avoided.

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 also all combinations of at least two of in the description, the claims and / or the figures revealed Features.

Of the Invention is based on the idea within the sleeve-shaped Steuerventilelementes a pressure pin for receiving the in axial Direction acting fuel pressure to arrange and this pressure pin as separate from the device equipped with the control valve seat Form component. Depending on the chosen, later It is still to be explained embodiment conceivable that the pressure pin as a guide element for the sleeve-shaped control valve element is or that additionally or alternatively an external guide for guiding the sleeve-shaped control valve element is provided on its outer periphery. In particular, then when the guide pin is designed as a freely adjustable component is formed in one of the concept of the invention Injector by a displacement of the guide pin at the assembly a compensation of angular errors and a compensation of a Axialversatzes the sleeve-shaped control valve element possible. Theoretically, it is conceivable, the control valve seat spherical form, an additional possibility to create angular error between the control valve element and the To compensate for the valve seat having component. It has However, it proved that the production of a part-spherical Control valve seat is expensive, since this shape difficult to grind and metrologically. According to the invention is therefore provided, the separate pressure pin with an outer cone combine trained control valve seat. With such a thing molded control valve seat can be similar to however, compensate for angular error in a spherical control valve seat is an outer cone as a control valve seat comparatively easy to manufacture and easy to measure. Due to the separate training of pressure pin and the component with control valve seat the control valve seat is easily accessible, so that the control valve seat is easily manufacturable. In addition, the control valve seat and the leadership for the sleeve-shaped Control valve element due to the arrangement of different Components are processed separately from each other. By the combination from a designed as an outer cone control valve seat with a separate pressure pin is so easy to be finished Injector created in a simple way in the axial direction pressure balanced can be formed. The sleeve-shaped ge Control valve element has in its the seat facing End with advantage a high radial stiffness. In addition generated the control valve seat formed as an outer cone centering forces by the control valve element optimally centered to the control valve seat is.

Of particular advantage is an embodiment in which the control valve, more precisely the control valve element, as in its closed position in the axial direction pressure-compensated component is formed. This can be realized, for example be that the sleeve-shaped control valve element is seated with its inner circumference on the outer cone designed as a control valve, so that a linear sealing surface is obtained without pressure level.

In Development of the invention is provided with advantage that the Outside cone of the control valve seat an outer cone angle from a value range between about 60 ° and about 80 °. Under outer cone angle is the angle of the outer cone surface to the longitudinal central axis of the control valve seat (outer cone) Understood. Preferably, the outer cone angle of a Range selected between about 70 ° and about 75 °.

From particular advantage is an embodiment in which with the designed as an outer cone control valve seat cooperating, axially adjustable, sleeve-shaped control valve element an inner cone is provided. Preference is given to the inner cone angle, ie the angle of the inner cone surface and the longitudinal center axis the inner cone, larger than the outer cone angle. As a result, on the one hand, a ring-shaped and linear sealing surface realized.

There the control valve seat of the preferably pressure-balanced control valve is inevitably subject to wear over its lifetime, is It is advantageous to the actual seating area on the sleeve-shaped Limit control valve element in the radial direction. This is in a designed as an outer cone control valve seat surprisingly very easy to realize. The maximum extent of getting through Wear-increasing sealing surface can be limited to a maximum by the Control valve seat facing end face of the control valve element from a radially outwardly of the inner cone lying, annular, itself perpendicular to the longitudinal extent of the valve sleeve, ie is limited in the radial direction extending end surface. Because of the maximum size of it Wear increasing sealing surface between Control valve element and control valve seat is limited, too a minimum of surface pressure in the sealing area the control valve element guarantees, which in turn leads to that the tightness of the control valve element over the life of the injector is ensured.

Especially preferred is an embodiment in which the axial Distance between the annular, formed by the inner cone Seat line (sealing surface) and in the radial direction extending end surface of the control valve element less than 400 microns, preferably less than 300 microns, especially preferably less than 200 microns, is. hereby can be the maximum frontal, radial extension of the seat line be kept to a minimum by wear, which is also the case with an injector that has been in operation for a long time still to a high surface pressure in Anla area of the sleeve-shaped control valve element on the control valve seat leads.

In terms of the arrangement and design of the pressure pin is there, as in the beginning mentioned, different possibilities. So is For example, it is conceivable that the pressure pin as an inner guide element is formed for the control valve element, so the control valve element with its cylindrical inner circumference on the outer circumference of Pressure pin is guided. For this it is necessary, the Position the pressure pin firmly inside the injector. This can be realized, for example, that the pressure pin on one of the control valve seat having the component in axial Direction spaced component, for example, form-fitting, set or integral with this one. For example, it acts this component is a plate on which there is an electromagnet arrangement an electromagnetic actuator is supported in the axial direction. Preferably, the pressure pin passes through this electromagnet arrangement in the axial direction. Alternatively, it is conceivable, the guide element by means a spring in the axial direction against a component which in axial Direction spaced from the control valve seat having the component is to apply a spring force.

additionally or preferably as an alternative to the formation of the pressure pin as inner guide element may be an embodiment the injector can be realized in which an external guide is provided for the control valve element, the control valve element so guided on its outer circumference. At a Such embodiment, it is advantageous if the Pressure pin is designed as an independent component, which when switched off the internal combustion engine to the control valve seat having component rests and when pressurized supported on a component axially arranged by this component.

Prefers it is the injector with pressure pin and outside conical Control valve seat around an injector with an electromagnetic Actuator for actuating the control valve.

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 schematic representation of an injector with a control valve, the sleeve-shaped control valve element is penetrated by a separate pressure pin, wherein the control valve element with a valve seat formed as an outer cone is formed and arranged cooperatively and

2 a schematic representation of a section of an alternative trained injector.

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 an injector designed as a common rail injector 1 for injecting fuel in a combustion chamber of an internal combustion engine of a motor vehicle. A high pressure pump 2 Promotes fuel from a reservoir 3 in a high-pressure fuel storage 4 (Rail). In this fuel, especially diesel or gasoline, under high pressure, of about 2000 bar in this embodiment, stored. To the high-pressure fuel storage 4 is the injector 1 in addition to other, not shown injectors via a supply line 5 connected. The supply line 5 flows into a pressure room 6 and in a lower in the drawing plane nozzle chamber 7 , By means of a return line 8th is a low pressure area 9 of the injector 1 to the reservoir 3 connected. About the return line 8th may be a later to be explained control amount of fuel from the injector 1 to the reservoir 3 flow away.

Within an injector body 10 is a control rod 11 one in this embodiment of control rod 11 and a nozzle needle 12 existing injection valve element 13 arranged. The control rod 11 the injection valve element 13 is longitudinally displaceable in a lower portion of the sleeve-shaped component 14 guided. In a low-pressure room 15 in the drawing plane axially below the pressure chamber 6 arranged and with a sealing element 16 is sealed against this, lies the control rod 11 with its lower end face on an upper end side of the nozzle needle 12 which is axially displaceable within a nozzle body 18 is guided. The nozzle body 18 is by means of a union nut, not shown, with the injector body 10 screwed. The low-pressure room 15 is over a channel 19 with the low pressure area 9 connected to the injector. Inside the low pressure room 15 has the injection valve element 13 a diameter step 42 (Low pressure stage), resulting in a fast closing behavior of the injector 1 is ensured.

The nozzle needle 12 has at its peak 20 a closing area 21 on, with which the nozzle needle 12 , So the injection valve element 13 in close contact with one inside the nozzle body 18 trained injection valve element seat 22 can be brought.

When the injection valve element 13 at its injection valve element seat 22 is applied, that is, is in a closed position, the fuel outlet from a nozzle hole arrangement 23 blocked. On the other hand, is it from its injection valve element seat 22 lifted off, can fuel from the nozzle chamber 7 over one in a lower area between nozzle needle 12 and nozzle body 18 trained annulus 24 at the injection valve element seat 22 over to the nozzle hole arrangement 23 flow and there are essentially injected under high pressure (rail pressure) standing in a combustion chamber.

From an upper front side 25 the control rod 11 the injection valve element 13 , which in addition to the multi-part design shown can also be formed in one piece, and in the drawing plane lower, sleeve-shaped portion of the device 14 becomes a control chamber 26 bounded over a radially in the sleeve-shaped portion of the device 14 running inlet throttle 27 with high-pressure fuel from the pressure chamber 6 is supplied. The control chamber 26 is above, in the upper, plate-shaped portion of the device 14 arranged drainage channel 28 with outlet throttle 29 with a valve chamber 30 connected, the radially outward of a sleeve-shaped control valve element 31 a control valve 32 (Servo valve) is limited. For this fuel can in the low pressure range 9 of the injector 1 when it flows from an electromagnetic actuator 33 actuatable control valve element 31 from its designed as an outer cone and on the plate-shaped portion of the component 14 arranged control valve seat 34 lifted, ie the control valve 32 is open. The flow cross sections of the axial throttle 27 and the outlet throttle 28 are matched to one another in such a way that when the control valve is open 32 a net outflow of fuel (tax amount) from the control chamber 26 over the valve chamber 30 in the low pressure area 9 of the injector 1 and from there via the return line 8th in the reservoir 3 he follows.

The control valve 32 is formed as in the closed state in the axial direction pressure compensated valve, wherein the control valve element 31 in its upper part in the plane of the drawing in one piece with an anchor plate 35 that with an electromagnet arrangement 36 of the actuator 33 cooperates, is formed. Be electromagnets 37 of the electromagnetic actuator 33 energized, raises the sleeve-shaped control valve element 31 from its exterior conical control valve seat 34 down, reducing the pressure inside the control chamber 26 rapidly drops and the control rod 11 in the axial direction in the plane of the drawing up in the control chamber 26 moved in, which also causes the nozzle needle 12 due to the fuel pressure within the nozzle space 7 in the drawing plane upwards in the direction of the low-pressure room 15 is moved in and in the sequence of fuel from the nozzle chamber 7 can flow into the combustion chamber.

At the end of the injection process, the energization of the electromagnets 37 of the actuator 33 interrupted. A control closing spring 40 located on a component designed as an injector cover 41 supports, moves the sleeve-shaped control valve element 31 back on its exterior conical control valve seat 34 at the upper side of the component in the plane of the drawing 14 , Through the through the inlet throttle 27 As fuel flows, the pressure in the control chamber increases 26 rapidly, causing the control rod 11 and subsequently the nozzle needle 12 , supported by the spring force of a closing spring 38 who are working on a perimeter 39 the control rod 11 supported, in the direction of the injection valve element seat 22 is moved, whereby the fuel flow from the nozzle hole arrangement 23 is interrupted in the combustion chamber.

Within the control valve element 31 is a push pin 43 recorded, the pressure forces acting in the axial direction within the valve chamber 30 picks up and the valve chamber 30 in the axial direction in the plane of the drawing seals upwards. The pressure pin 43 relies on that of the component 14 arranged component 41 from what the pressure pin 43 the electromagnet arrangement 36 of the actuator 33 interspersed in the axial direction. When the internal combustion engine is switched off, the pressure pin drops 43 from and is up to the repressurization at the top of the outer conical control valve seat 34 on.

To guide the sleeve-shaped control valve element 31 is a guide plate 44 (External guide) provided, which is the control valve element 31 on its outer circumference leads. As a result, the trained as a separate component, loose pressure pin 43 no guide function, but only serves to absorb forces acting in the axial direction. In the guide plate 44 is an axial channel 45 provided to the fuel flow within the low-pressure area to an armature space 46 and from there via a centric, from the pressure pin 43 interspersed opening 51 in which also the tax closing pen 40 is arranged, to the return line 8th to ensure.

As in particular from 2 can be seen, showing a slightly modified embodiment or a section of this, has the control valve element 31 a radially inner cone located inside 47 on. From this is a seat line on the inner circumference 48 (Sealing line) formed by means of the control valve element 31 with the control valve seat 34 interacts. How out 2 is apparent, is an inner cone angle α of the inner cone 47 greater than an outer cone angle β of the outer cone-shaped control valve seat 34 ,

Radial to the inner cone 47 closes an end face 49 the control valve element 31 at. The distance A between the seat line 48 and the annular end surface 50 is less than 200 microns in the embodiment shown. The perpendicular to the longitudinal center axis L of the control valve seat 34 extending end surface 49 limits the wear-increasing, maximum extension of the seat line 48 , which ensures a sufficiently high surface pressure even after a long period of operation.

In contrast to the embodiment according to 1 serves the pressure pin 43 in the embodiment according to 2 as an inner guide for the sleeve-shaped control valve element 31 , To ensure this, the tax closing spring is based 40 on the one hand on the control valve element 31 and on the other hand on an annular shoulder 50 of the pressure pin 43 from and pressed it against the serving as a lid component 41 ,

How out 2 can be seen, includes radially outward on the flat, extending in the radial direction end face 49 the control valve element 31 a radially outer chamfer portion 17 at.

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, with an injection valve element which is adjustable between a closed position and an open position releasing the fuel flow (US Pat. 13 ), which by means of one, a sleeve-shaped control valve element ( 31 ), control valve ( 32 ) is controllable, wherein the control valve element ( 31 ) with one on a component ( 14 ) arranged control valve seat ( 34 ), characterized in that one of the control valve element ( 31 ) more enclosed, of the component ( 14 ) separate pressure pin ( 43 ) is provided and that the control valve seat ( 34 ) is designed as an outer cone. Injector according to claim 1, characterized in that the control valve ( 32 ) is formed pressure-balanced in the axial direction in the closed state. Injector according to one of claims 1 or 2, characterized in that the outer cone has an outer cone angle (α) from a range between about 60 ° and about 80 °, preferably between about 70 ° and about 75 °. Injector according to one of the preceding claims, characterized in that the control valve element ( 31 ) in the direction of the control valve seat ( 34 ) has an opening inner cone. Injector according to claim 4, characterized that the outer cone angle (β) is smaller than the inner cone angle (α). Injector according to one of the preceding claims, characterized in that the control valve element ( 31 ) seat side of an annular and perpendicular to the longitudinal extent of the control valve element ( 31 ) extending end surface ( 49 ) is limited. Injector according to one of the preceding claims, characterized in that the axial distance (A) of a seat line formed by the inner cone ( 48 ) to the annular end surface ( 49 ) is less than 400 microns, preferably less than 300 microns, more preferably less than 200 microns, is. Injector according to one of the preceding claims, characterized in that the pressure pin ( 43 ) as an inner guide element for the control valve element ( 31 ) and at one of which the control valve seat ( 34 ) having component ( 14 ) spaced component ( 41 ) or integrally formed with this or is spring-loaded against this or is supported on this when pressurized. Injector according to one of the preceding claims, characterized in that the control valve element ( 31 ) is guided on its outer circumference. Injector according to one of the preceding claims, characterized in that an electromagnetic actuator ( 33 ) for actuating the control valve ( 32 ) is provided.