DE102007018006A1 - injector - Google Patents

Abstract

The invention relates to an injector (1) with a valve element (5) which can be adjusted in the axial direction between a closed position and an open position opening the fuel flow through a nozzle hole arrangement (12) into the combustion chamber and with a valve element (15) between an injector body (2) and a valve element (15 ) formed annular space (14) into which a fuel supply channel (13) opens for fuel under high pressure, and with an axially to the annular space (14) adjacent the pressure chamber (18). According to the invention, an annular throttle part (17) supporting at least one throttle opening (18) on the one hand on the valve piece (15) and on the other hand on the injector body (2) is received in the annular space (14) Fuel from the annulus (14) in the pressure chamber (18) can flow.

Description

State of the art

The The invention relates to an injector according to the preamble of claim 1.

From the DE 100 20 870 A1 as well as from the EP 1 722 101 A1 Injectors for injecting fuel into the combustion chamber of an internal combustion engine are known in which an annular space is sealed against a space lying at low pressure by means of an annular sealing element which is provided with a support structure. The sealing element thus prevents the penetration of high pressure fuel from the annulus in the adjacent to low pressure space, which is usually associated with a diameter stage of a valve element of the injector to produce a closing force component.

Besides Injectors are known in which the annular space into which opens a fuel supply channel, in the axial direction in a pressure chamber, in the the fuel supplied from the fuel supply passage flows in to open valve element by having at least one injection port Nozzle hole arrangement in the combustion chamber of the internal combustion engine to be sprayed. These, referred to as leak-free injectors Injectors (usually without low pressure stage) must be the nozzle hole arrangement supplied fuel is (slightly) throttled, so that the fuel pressure in the area of the valve element tip (something) less than the rail pressure to a sufficiently high closing force Ensure to close the valve element to be able to.

to Realization of fuel throttling by means of a throttle bore There are basically two ways known. On the one hand, the throttle bore in an inlet channel to the below provided the annulus pressure chamber provided in the injector body become. The effort for the production of this variant is but considerably and therefore for cost reasons as possible avoided. On the other hand, it is known that at least one throttle bore in an additional throttle plate between the injector body and to arrange the nozzle body, so hydraulically Seen between the pressure chamber located below the annulus and the nozzle hole arrangement. This variant is less costly than the variant outlined above, but has functional Disadvantage. For one thing, the nozzle hole arrangement is no longer connected directly to the pressure chamber, so that the metering accuracy reduced in multiple injections and on the other hand it can through Verwirbelungseffekte at the inlet of the throttle bore in the throttle plate come to inaccuracies in the Mengenzumessung. Continues to emerge an additional high-pressure sealing point, merely by pressing the injector body together, the throttle plate and the nozzle body are sealed must (hard seal). The design of such a hard seal For high pressures causes a high production cost.

Disclosure of the invention

Technically task

Of the The invention is therefore based on the object of proposing an injector, wherein the throttling of the nozzle hole arrangement supplied Fuel compared to the supply pressure to simple alternative way without negative effects on the metering accuracy is realized.

Technical solution

These The object is achieved with the feature of claim 1. advantageous Further developments of the invention are in the subclaims 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.

The invention is based on the idea to realize the throttling of the fuel with a separate fitting, namely an annular throttle member which is disposed within the annulus and on the one hand to the annular space radially inwardly limiting valve piece and on the other hand, the annular space radially outwardly limiting injector body supported. The throttle part is not an integral part of the housing (injector body, nozzle body) and it arises due to the omission of a throttle plate between the nozzle body and injector not additionally sealed to the outside body. In the throttle member at least one, preferably axial throttle opening is introduced, can flow through the under high pressure fuel from the annulus in the pressure chamber. Further throttling of the fuel on its way to the nozzle hole arrangement with at least one injection opening does not have to take place. Preferably, the throttle member is provided with a plurality, in particular evenly distributed over its circumference throttle openings or channels. The adjacent pressure chamber in the axial direction of the annulus pressure chamber serves as a mini-rail, the pressure oscillations, which are always triggered by the opening and closing of the nozzle needle in common-rail systems are greatly reduced in amplitude. As a result, the influence of these pressure waves on the Einspritzmengenzumessung at multiple injections is drastically reduced. The inserted valve element can be both one-piece, as well as multi-part, in particular two-piece with control be formed piston and nozzle needle. Preferably, the valve piece, on which the throttle part is supported, provided with a receiving bore for the valve element, so that the valve piece serves as a guide for the valve element, in particular for a control piston of the valve element.

In Development of the invention is provided with advantage that the at least one throttle opening (at least substantially) the only hydraulic connection between the annulus and the axially adjacent pressure chamber. In other words, lies the throttle member at least approximately sealed to the Valve piece and on the injector body, wherein minor leaks on the edge of the throttle body without (essential) importance.

In Embodiment of the invention is provided with advantage that the Throttle part, at least in sections, a Me is tallteil. there It is conceivable that the edge elastic plastic material to improve the sealing effect is provided. Preferably, the throttle member is for However, reduction of wear completely made of metal. A (possibly complete) education However, from a robust plastic is also conceivable.

Prefers the throttle member in the axial and / or radial direction is elastic resilient, in particular a sealing, clamping recording the throttle part between the valve piece and the injector body to ensure.

From particular advantage is an embodiment in which the annular throttle part formed as a plate spring element is. By the curved, extending in the axial direction Training is the bridging of an axial distance between the contact points on the valve piece and on the injector body possible.

Prefers is an embodiment in which a secure hold of the Throttle part is ensured in the injector thereby that the throttle part between two annular shoulders or between two Steps on the one hand of the valve piece and on the other hand of the injector body is arranged to slip in the axial direction or even a complete release to avoid the throttle part from its mounting position.

One Particularly good hold of the throttle part can be realized by the two ring shoulders in the axial direction and also preferred offset in the radial direction to each other, d. H. spaced apart are.

Around a good seal of the throttle body relative to the valve piece as well as with respect to the injector body and simultaneously to realize a secure hold of the throttle part in the injector, is provided in an embodiment of the invention advantageously that the Axial extent of the throttle member in the installed state is lower when not installed, that throttle part during assembly So, preferably elastically deformed.

In Development of the invention is provided with advantage that the in the annulus fuel supply channel opening only fuel supply channel is and thus a control chamber, which is preferably limited by the valve piece, through an inlet throttle from the annulus with high-pressure Fuel is supplied. The flow rate of the inlet throttle for Control chamber and the pressure drop at the at least one throttle opening of the throttle part essentially determine the closing speed of the valve element.

From particular advantage is a variant in which on a feeder of high-pressure fuel through a throttle channel in the injector body to a separate nozzle chamber is dispensed with in the nozzle body. Preferably flows the fuel from the pressure chamber either directly to the nozzle hole arrangement or takes the detour via a channel in the nozzle body to a nozzle space (annulus) in the nozzle body and then flows from there through a Umfangsgalt Nozzle hole arrangement. The channel is designed throttle-free.

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 representation of a common rail injector,

2 a sectional detail view of the installation situation of a throttle part in the injector,

3 a plan view of the throttle part and

4 a sectional view of the throttle part along the section line AA according to 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 an injector designed as a common rail injector 1 for injecting fuel into a combustion chamber of an internal combustion engine ne shown. The injector 1 includes an injector body 2 and one by means of a nozzle locknut 3 attached nozzle body 4 , In the injector body 2 as well as in the nozzle body 3 is a common valve element 5 axially slidably received, wherein the valve element 5 from a control piston 6 and a hydraulically coupled nozzle needle 7 consists. The hydraulic coupling takes place within a coupler space 8th that of a sleeve 9 is limited. In this case, the sleeve by means of a compression spring 10 on an upper end side of the nozzle body 4 Federkraftbeaufschlagt, wherein the sleeve 9 the control piston 6 completely encloses.

In the closed position shown, the nozzle needle is located 7 on her jet needle seat 11 on and thus blocks a nozzle hole arrangement 12 , When the valve element is open, fuel from the nozzle hole arrangement 12 flow into a combustion chamber, not shown, of an internal combustion engine.

The from the nozzle hole arrangement 12 escaping fuel passes through an in 2 shown fuel supply channel 13 , which is connected to a fuel high pressure accumulator (rail), not shown, in an annulus 14 , where the annulus 14 radially outward of the injector body and radially inward of a valve piece 15 is limited.

Starting from the annulus 14 the fuel flows through throttle openings 16 (see. 2 ) of an annular throttle part 17 and thus enters a pressure chamber 18 (Mini-rail), inside the injector body 2 , In the pressure room 18 is a valve closing spring 19 arranged, which at one end at a lower end side of the valve piece 15 and other end on one at the spool 6 held circlip 20 supported. Through the pressure room 18 the high pressure fuel flows up to the sleeve 9 and by a circumferential gap between the sleeve 9 and injector body 2 through to the front of the nozzle body 3 and from there through a throttle-free channel 21 to a nozzle room 22 inside the nozzle body 4 , From there, the fuel flows through the annular gap between the nozzle needle 7 nozzle body 4 to the nozzle hole arrangement 12 ,

For axial adjustment of the valve element 5 is one of the end face of the control piston 6 limited control chamber 23 provided that has an in 2 shown inlet throttle 24 with high-pressure fuel from the annulus 14 is supplied. The control chamber 23 is a control valve 25 associated, which in this embodiment by means of an electromagnetic actuator 26 is operable. With open control valve 25 fuel flows through an outlet throttle 27 in a low pressure region of the injector and from there to a return line. The flow cross sections of the inlet throttle are 24 and the outlet throttle 27 coordinated so that when open control valve 25 a net outflow from the tax chamber 23 resulting, whereby the valve element 5 lifts off the nozzle needle seat and thus releases the flow of fuel into the combustion chamber. To close the valve element 5 becomes the control valve 25 by means of the electromagnetic actuator 26 closed, reducing the pressure in the control chamber 23 by the inflow of fuel from the annulus 14 through the inlet throttle 24 increases, which in turn results in a resultant closing force on the valve element 5 acts.

How out 2 can be seen, limits the valve piece 5 not just the annulus 14 but also the control chamber 23 and also serves to guide the control piston 6 , In the valve piece 15 is also the inlet throttle 24 brought in.

How out 2 can be seen, is the throttle part 16 formed in the manner of a plate spring made of metal and lies at one end on a first annular shoulder 28 of the injector body 2 and at the other end on a second ring shoulder 29 of the valve piece 15 on, with the two ring shoulders 28 . 29 offset in the axial direction and are arranged slightly overlapping in the radial direction. For a particularly secure hold of the throttle part 17 It is intended that this will be in corners 30 . 31 the ring shoulders 28 . 29 supports and thus also in the radial direction sealingly on the valve piece 15 and on the injector body 2 is applied.

In 3 is the throttle part 17 shown in a plan view. Evident are three evenly distributed over the circumference throttle openings 16 , Seen in the radial direction approximately centrally on the annular throttle part 17 are located.

In 4 is the throttle part 17 in a sectional view along the section line AA according to 3 shown. Evident is the curved formation with the central throttle opening 16 , The throttle part 17 has him unassembled state a greater axial extent A than in the assembled state. In other words, the throttle part 17 in the assembled state elastically between the valve piece 15 and the injector body 2 clamped.

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

• - DE 10020870 A1 [0002]
• EP 1722101 A1 [0002]

Claims (10)

Injector for injecting fuel into the combustion chamber of an internal combustion engine, in particular a common rail injector, with an axial direction between a closed position and a fuel flow through a nozzle hole arrangement ( 12 ) in the combustion chamber releasing open position adjustable valve element ( 5 ), and with one between an injector body ( 2 ) and a valve piece ( 15 ) formed annular space ( 14 ) into which a fuel supply channel ( 13 ) opens for high-pressure fuel, and with an axial to the annulus ( 14 ) adjacent pressure space ( 18 ), characterized in that in the annulus ( 14 ) an annular, on the one hand on the valve piece ( 15 ) and on the other hand on the injector body ( 2 ) supporting throttle part ( 17 ) with at least one throttle opening ( 16 ) is absorbed by the high-pressure fuel from the annulus ( 14 ) into the pressure chamber ( 18 ) can flow. Injector according to claim 1, characterized in that the throttle part ( 17 ) at least approximately sealingly on the valve piece ( 15 ) and on the injector body ( 2 ) is present. Injector according to one of claims 1 or 2, characterized in that the throttle part ( 17 ), at least in sections, preferably completely, is formed of metal. Injector according to one of the preceding claims, characterized in that the throttle part ( 17 ) is resilient in the axial and / or radial direction. Injector according to one of the preceding claims, characterized in that the throttle part ( 17 ) is a plate spring element. Injector according to one of the preceding claims, characterized in that the throttle part ( 17 ) in a first axial direction on a first annular shoulder ( 28 ) of the injector body ( 2 ) and in a second, the first axial direction opposite axial direction at a second annular shoulder ( 29 ) of the valve piece ( 15 ) is supported. Injector according to claim 6, characterized in that the first and the second annular shoulder ( 28 . 29 ) are axially offset from one another. Injector according to one of the preceding claims, characterized in that an axial extension (A) of the throttle part ( 17 ) before its mounting is greater than the axial distance between the two annular shoulders ( 28 . 29 ). Injector according to one of the preceding claims, characterized in that of the annular space ( 14 ) at least one inlet throttle ( 24 ) in a control chamber ( 23 ), which via a control valve ( 25 ) is hydraulically connectable to a low pressure region of the injector. Injector according to one of the preceding claims, characterized in that when the valve element is open ( 5 ) under high pressure fuel through throttle opening ( 16 ) of the throttle part ( 17 ) and the pressure chamber ( 18 ) in the axial direction and to the nozzle hole arrangement ( 12 ) flows.