DE102008041167A1 - Fuel injector for storage-type injector systems for injecting pressurized fuel into combustion chamber of internal combustion engine, has injector housing, which comprises internal high-pressure volume for injecting highly pressurized fuel - Google Patents

Abstract

The fuel injector (1) has an injector housing (2), which comprises an internal high-pressure volume (30) for injecting highly pressurized fuel into a combustion chamber of an internal combustion engine. The internal high-pressure volume is divided into two coaxial chamber sections (31,32).The chamber sections extend coaxially or radially to an injection valve (10).

Description

The The invention relates to a fuel injector for accumulator injection systems, for injecting high-pressure fuel into a combustion chamber an internal combustion engine, having an injector housing that includes an internal high pressure volume, from the high-pressure fuel into a combustion chamber an internal combustion engine is injected.

fuel injectors can with a relatively large one internal high-pressure volume can be equipped to unwanted pressure oscillations between the fuel injector and a central fuel high pressure source outside of the fuel injector.

Disclosure of the invention

task The invention is the propagation of unwanted pressure oscillations in a fuel injector according to the preamble of claim 1 to prevent.

The Task is with a fuel injector for storage injection systems, for injecting high-pressure fuel into a combustion chamber an internal combustion engine, having an injector housing that includes an internal high pressure volume, from the high-pressure fuel into a combustion chamber an internal combustion engine is injected, thereby achieved that the internal high-pressure volume in at least two coaxially arranged annular spaces is divided. For investigations carried out in the context of the present invention It was found that by a relatively large internal high pressure volume Although low-frequency pressure waves can be damped, but in the relatively large internal high-pressure volume high-frequency pressure oscillations that can occur can adversely affect a multiple injection. By the subdivision according to the invention of the internal high pressure volume Both low-frequency and high-frequency pressure waves or pressure oscillations be particularly effectively damped in the fuel injector.

One preferred embodiment the fuel injector is characterized in that the Rinräume coaxial with and radially outside an injection valve member extend. By the clever arrangement the annuli Only slightly more space is required than in conventional Injectors.

One Another preferred embodiment the fuel injector is characterized in that the annular spaces in the radial Direction through a sleeve are separated from each other. The sleeve has essentially the shape of a straight hollow cylinder and can be made of steel, for example. In the installed state can the sleeve be clamped in the axial direction between two housing parts.

One Another preferred embodiment the fuel injector is characterized in that the sleeve at least having a throttle connection, which the two annular spaces with each other combines. The throttle connection may also be in another injector housing part to be ordered. Through the throttle connection, the two annular spaces are hydraulic coupled together. About that In addition, the throttle connection the task of a closing throttle fulfill. A closing throttle elevated the closing force to the injection valve member, which in pressure compensated injection valve members is advantageous.

One Another preferred embodiment the fuel injector is characterized in that a high-pressure inlet channel in the outer or opens the inner annulus. The direct connection of the inner annulus to the high-pressure inlet channel has the advantage that the outer annulus as good as not too unwanted Pressure oscillations is excited. So the outer annulus can only the Function of a pressure damper exercise. However, it may be easier to manufacture, the outer annulus to connect to the high-pressure inlet channel.

One Another preferred embodiment the fuel injector is characterized in that the outer annulus a larger volume has as the inner annulus. The volume of the outer ring space preferably represents a hydraulic damping volume.

One Another preferred embodiment the fuel injector is characterized in that the inner Annulus is associated with a high pressure room, from the with High-pressure fuel is injected when a or the injection valve member or the fuel injector opens. Of the inner annulus preferably provides a supply bore to a Nozzle dar. Alternatively, the outer annulus communicate with the high pressure room.

Another preferred exemplary embodiment of the fuel injector is characterized in that the two annular spaces are connected to one another by a multiplicity of connecting channels provided in the sleeve. Due to the large number of connecting channels one loses itself between a nozzle and a high-pressure connection spreading pressure wave continuously on its way to energy, while the fuel in the outer annulus is only very slightly excited.

One Another preferred embodiment the fuel injector is characterized in that the connecting channels in a longitudinal wave direction are evenly distributed. Thereby can be a pressure wave, which in the inner annulus in longitudinal Direction between a nozzle and a high-pressure connection propagates, be particularly strongly damped.

One Another preferred embodiment the fuel injector is characterized in that the connecting channels a have so small passage cross-section that they have a filter function exercise. This prevents impurities contained in the fuel get to at least one spray hole and this clog. Therefore a gap filter at the entrance of the fuel injector can be omitted.

Further Advantages, features and details of the invention will become apparent the following description, with reference to the drawing various embodiments are described in detail.

Short description of the drawing

It demonstrate:

1 a simplified representation of a fuel injection injector in longitudinal section with a sleeve which divides an internal high-pressure volume into two annular spaces;

2 a similar fuel injector as in

1 wherein the sleeve has a plurality of connecting channels and

3 a similar fuel injector as in

2 , wherein a high-pressure fuel inlet is connected to an inner annular space.

Description of the embodiments

In the 1 to 3 is a fuel injector 1 ; 41 ; 51 each shown simplified in longitudinal section. To designate the same parts, the same reference numerals are used. The fuel injector 1 ; 41 ; 51 includes a multi-part injector housing 2 , The injector housing 2 is via a high-pressure fuel supply line or a fuel high-pressure inlet channel 3 from a central high-pressure fuel source 4 supplied with fuel, which is subjected to high pressure. The central high-pressure fuel source 4 outside the fuel injector 1 ; 41 ; 51 is also referred to as common rail. Therefore, the high pressure, which can be significantly more than 1000 bar, also referred to as rail pressure.

The multipart injector housing 2 includes a holding body 6 , an injector body 7 and a nozzle body 8th , An intermediate body 9 is in the axial direction between the nozzle body 8th and the injector body 7 clamped. As the axial direction, the longitudinal expansion direction of the fuel injector 1 ; 41 ; 51 also designates the direction of movement of an injection valve member 10 corresponds to that in the injector housing 2 is guided back and forth movable.

The injection valve member 10 can be made in one piece or multiple parts and is also referred to as a nozzle needle. At the end of the nozzle needle near the combustion chamber 10 Preferably, a tip is formed with a sealing edge, which with a sealing surface on the nozzle body 8th cooperates to form a sealing seat. The tip of the combustion chamber near the end of the nozzle needle 10 juts into a central blind hole 11 that in the nozzle body 8th is omitted. The combustion chamber remote end of the nozzle needle 10 limits a control room 12 , by the pressure of an opening of the nozzle needle 10 can be effected.

If the nozzle needle 10 due to a pressure drop in the control room 12 lifts off with its tip from the associated sealing seat, then passes pressurized fuel from a high-pressure chamber 13 . 14 in the nozzle body 8th past the nozzle needle tip into the blind hole 11 from where the high-pressure fuel through at least one spray hole 15 is injected into a combustion chamber of an internal combustion engine. Closing the nozzle needle 10 is through a nozzle needle closing spring 16 assists when the pressure in the control room 12 increases again.

The control room 12 is from a valve piece 18 limited, with the help of a clamping screw 20 in the holding body 6 is attached. The valve piece 18 belongs to a solenoid valve device 24 that have a valve room 25 includes, as by an arrow 26 is indicated, is associated with a return. The associated return pressure is significantly smaller than the high pressure or rail pressure and can be, for example, about 10 bar.

With the help of the solenoid valve device 24 can the pressure in the control room 12 be selectively lowered to open the nozzle needle 10 to effect. The pressure in the control room 12 But it can also be done in other ways, for example Help a piezoelectric actuator, be lowered. The nozzle needle 10 includes a first guide portion 27 through which the nozzle needle 10 in the region of its end close to the combustion chamber in the nozzle body 8th is guided. Through a second guide section 28 is the nozzle needle 10 at its combustion chamber remote end in the valve piece 18 guided.

The injector housing 2 includes within the injector body 7 and the holding body 6 an internal high pressure volume 30 , which is filled with fuel, which is subjected to high pressure. According to an essential aspect of the invention is the internal high-pressure volume 30 in an inner annulus 31 and an outer annulus 32 divided. The two annular spaces 31 . 32 are coaxial with each other and coaxial with the injection valve member 10 in the injector housing 2 arranged. In the radial direction are the two annular spaces 31 . 32 arranged so that the outer annulus 32 the inner annulus 31 surrounds. The inner annulus 31 becomes radially inward of the injection valve member 10 limited. The outer annulus 32 is radially outward of the injector body 7 and the holding body 6 limited.

At the in 1 illustrated embodiment, the two annular spaces 31 . 32 through a sleeve 35 separated from each other in the axial direction between the valve piece 18 and the intermediate body 9 is clamped. The sleeve 35 has substantially the shape of a straight circular cylinder jacket, which is coaxial with the injection valve member 10 is arranged. In the area of its combustion chamber near end, the sleeve 35 a throttle connection 38 on which the two annuli 31 . 32 connects with each other. The throttle connection 38 can be designed as a throttle bore and not only provides a hydraulic coupling of the two annular spaces 31 . 32 but additionally fulfills the task of a closing throttle. A closing throttle increases the nozzle needle closing force, resulting in pressure balanced injector members 10 is advantageous.

The high pressure supply line 3 or the high-pressure inlet channel 3 flows into the outer annulus 32 , About the throttle connection 38 reaches the high-pressure fuel from the outer annulus 32 in the inner annulus 31 , The inner annulus 31 stands over an annular gap 39 in the radial direction between the injection valve member 10 and the intermediate body 9 is provided, with the high-pressure chamber 13 . 14 in the nozzle body 8th in connection. Thus, the inner annulus provides 31 an inner supply bore to the combustion chamber near the end of the nozzle body 8th which is also referred to as nozzle. In contrast, the outer annulus has 32 the function of a hydraulic damping volume. For this reason, it is advantageous if the volume of the outer annulus 32 greater than the volume of the inner annulus 31 is.

By the inventive arrangement of the sleeve 35 and the associated arrangement of the two annular spaces 31 . 32 It is achieved that a pressure surge caused by the opening or closing of the nozzle needle 10 arises and starting from the nozzle direction rail 4 spreads, only to a small extent, a stimulation of injector-internal high-pressure volume 30 causes.

When the injection valve member 10 or the fuel injector 1 closes, then moves a pressure wave in the high-pressure chamber 13 . 14 and the inner annulus 31 coming from the nozzle in the direction of the high-pressure connection. The pressure wave is only partially on the radially arranged throttle connection 38 in the outer annulus 32 over, while the greater part of the pressure wave in the inner annulus 31 remains. After a short time, the reflected pressure waves will self-destruct or become via the throttle connection 38 reduced.

At the in 2 illustrated fuel injector 41 are the two annuli 31 . 32 through a sleeve 45 separated from each other, which has a variety of connecting channels 46 . 47 having. The connection channels 46 . 47 extend in the radial direction through the sleeve 45 and create a hydraulic connection between the two annular spaces 31 . 32 , The connection channels 46 . 47 are evenly distributed in a longitudinal wave direction. This special design of the connecting channels is a pressure wave, which is located in the inner annulus 31 formed in the longitudinal direction between the nozzle and the high pressure port, particularly heavily damped. Due to the large number of connection channels 46 . 47 The pressure wave continuously loses energy on its way, while the fuel in the outer annulus loses energy 32 is stimulated only very slightly. The connection channels 46 . 47 are preferably designed as holes and take over additionally the function of in 1 With 38 designated throttle connection.

The sleeve 45 According to another aspect of the invention, it may be designed to assume the function of a filter. For this purpose, the connection channels 46 . 47 designed as through holes with very small passage cross-sections. For the preparation of such connection channels 46 . 47 Laser drilling is particularly suitable. A so designed sleeve 45 represents an injector-internal filter that prevents impurities or fuel particles from clogging the spray hole 15 to lead. Thus, a conventional gap filter can be omitted at the injector.

At the in 3 illustrated fuel injector 51 is in contrast to the previous embodiments, a high-pressure annulus 52 in the radial direction between the valve piece 18 and the holding body 6 is arranged by a high pressure seal 53 from the outer annulus 32 separated. The high pressure annulus 52 is via a connection channel 54 , which is provided with a closing throttle, with the inner annulus 31 in connection.

The two annular spaces 31 . 32 are through a sleeve 55 separated from each other, which, as in the previous embodiment, a large number of connection channels 56 . 57 has, extending in the radial direction through the sleeve 55 extend. The connection channel 54 can be designed as a throttle bore. Due to the direct connection of the inner annulus 31 to the high pressure supply line 3 is achieved that the outer annulus 32 as good as not stimulated. The outer annulus 32 only performs the function of a pressure damper. The two annular spaces 31 . 32 are only via the connection channels 56 . 57 connected with each other. The passage cross section of the connecting channels 56 . 57 is to be made smaller in total than the passage cross-section of the closing throttle in the connecting channel 54 , Ideally, the passage cross section of the connecting channels 56 . 57 in the sum about half as large as the closing throttle cross section in the connecting channel 54 ,

Claims (10)

Fuel injector for storage injection systems, for injecting high-pressure fuel into a combustion chamber of an internal combustion engine, with an injector housing ( 2 ), which is an internal high-pressure volume ( 30 ) is injected from the high-pressure fuel into a combustion chamber of an internal combustion engine, characterized in that the internal high-pressure volume ( 30 ) in at least two coaxially arranged annular spaces ( 31 . 32 ) is divided. Fuel injector according to claim 1, characterized in that the annular spaces ( 31 . 32 ) coaxial with and radially outward of an injection valve member ( 10 ). Fuel injector according to one of the preceding claims, characterized in that the annular spaces ( 31 . 32 ) in the radial direction through a sleeve ( 35 ; 45 ; 55 ) are separated from each other. Fuel injector according to the preceding claim, characterized in that the sleeve ( 35 ) at least one throttle connection ( 38 ), which connects the two annular spaces with each other. Fuel injector according to one of the preceding claims, characterized in that a high pressure inlet channel ( 3 ) in the outer ( 32 ) or the inner ( 31 ) Annulus opens. Fuel injector according to one of the preceding claims, characterized in that the outer annular space ( 32 ) has a larger volume than the inner annulus ( 31 ). Fuel injector according to one of the preceding claims, characterized in that the inner annular space ( 31 ) with a high-pressure chamber ( 13 . 14 ) is injected, is injected from the high-pressure fuel when a or the injection valve member ( 10 ) or the fuel injector opens. Fuel injector according to one of the preceding claims, characterized in that the two annular spaces ( 31 . 32 ) by a plurality of in the sleeve ( 45 . 55 ) connection channels ( 46 . 47 ; 56 . 57 ) communicate with each other. Fuel injector according to the preceding claim, characterized in that the connecting channels ( 46 . 47 ; 56 . 57 ) are evenly distributed in a longitudinal wave direction. Fuel injector according to claim 8 or 9, characterized in that the connecting channels ( 46 . 47 ; 56 . 57 ) have such a small passage cross-section that they exercise a filter function.