WO2015106934A1

WO2015106934A1 - Fuel injector

Info

Publication number: WO2015106934A1
Application number: PCT/EP2014/078997
Authority: WO
Inventors: Armin Schuelke; Walter Fuchs; Olaf Ohlhafer
Original assignee: Robert Bosch Gmbh
Priority date: 2014-01-17
Filing date: 2014-12-22
Publication date: 2015-07-23
Also published as: DE102014200771A1

Abstract

The invention relates to a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising a clamping nut (1) in which a nozzle body (2) and a retaining body (3) are arranged, a needle body (4) which consists of an armature needle section (41) and a nozzle needle section (42) and is accommodated guided in the nozzle body (2), and a magnetic actuator (5), accommodated in the clamping nut (1) for direct actuation of the needle body (4) accommodated with a lifting movement in an inner bore hole (21) of the nozzle body (2), wherein by means of the lifting movement thereof at least one injection opening (22) can be opened or closed. The magnetic actuator (5) thus has a magnetic body (51) arranged in the retaining body (3), an annular magnetic coil (52) which is arranged between the nozzle body (2) and the retaining body (3), and an armature plate (53) functioning as an actuator, which is arranged on the armature needle section (41) and interacts with the magnetic coil (52). The fuel injector according to the invention further comprises a high pressure region (6) in which at least the armature needle section (41) of the needle body (4) is completely accommodated.

Description

description

title

Fuel! n each ktor state of the art

The present invention is apparent from a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine according to the species according to the preamble of independent claim 1. More specifically, the present invention relates to a fuel injector having a

Magnet actuator for direct actuation of a needle body received in a liftable manner in an inner bore of a nozzle body for opening or closing at least one injection opening, wherein the magnetic actuator has an annular magnetic coil with a as a solenoid plunger

trained actuator cooperates.

As can be seen in FIG. 2, it is known in the field of vehicle technology, for example from DE 10 2011 076 663 A1, to use an actuator arrangement for controlling the lifting movement of a nozzle needle 91 of a rail fuel injector 9, which is used to close off

Injection openings 92 is biased against this by a compression spring 93. The high-pressure fuel to be injected is led through a supply line 94 to the injection openings, wherein the control takes place directly. The actuator arrangement provided for the direct control of the nozzle needle 91 has two magnetic actuators 95, 96 which are each arranged in a low-pressure region for better control. The arrangement of the magnetic actuators 95, 96 in the low-pressure region, among other things, their load can be reduced. In order to transmit a stroke of the magnetic actuators 95, 96 to the nozzle needle 91, they each act together with a nozzle armature 91 arranged flat armature 97, wherein a alternating energization of the two magnetic actuators 95, 96 causes opening and closing of the nozzle needle 91. By applying the nozzle needle 91 with the spring force of the spring 93 and the application of the flat armature 97 by a further compression spring 98 in the closing direction, it follows that the closing of the nozzle needle 91 causing

Magnetic actuator 96 must have a comparatively low power. According to a further embodiment of DE 10 2011 076 663 A1, a hydraulic coupler can also be used to increase the force in the fuel! be provided 9, so that operation of the fuel! njektors 9 with

Injection pressures of up to 2500 bar can be implemented. Such fuel injectors are usually designed for a pressure range of 200 to 2500bar, the injector should be able to inject in the entire pressure range during operation. In order to fulfill a correspondingly error-free operation of the fuel injector 9 in the fuel injector 9 by means of the described complex structure in addition to the provision of two magnetic actuators 95, 96 of the low-pressure region of a

High-pressure region of the fuel acted upon with high pressure to be separated as fluid-tight as possible and it must usually be provided a return from the low-pressure region in the tank, which allows a return of an overflowed despite the sealing fuel. in the

However, in the automotive engineering field, it is generally a goal to reduce the complexity of assemblies as well as the number of their components, inter alia with a view to simplifying and accelerating the assembly, so as not to cause unnecessary excessive costs.

Disclosure of the invention

In order to solve the aforementioned problems of the known art, the present invention provides a fuel injector having the features of claim 1. Advantageous developments of the invention are specified in the subclaims.

More specifically, the fuel of the invention! to the injector

Injecting fuel into and into a combustion chamber of an internal combustion engine, such as a gasoline or diesel engine a clamping nut, one of a Ankernadelabschnitt and a

Düsennadelabschnitt existing one-piece needle body and a magnetic actuator recorded in the nut on. In this case, a nozzle body and a holding body are arranged in the clamping nut, wherein the needle body is received in an inner bore of the nozzle body guided hubbeweglich and is actuated directly by the magnetic actuator, and wherein at least one provided in the nozzle body injection port or nozzle on the

Lifting movement of the needle body is releasable or closable.

Preferably, two or more injection openings may be present. The magnetic actuator comprises one for actuating the needle body in the

Holding body arranged magnetic body, also referred to as the inner pole, an annular magnetic coil which between the nozzle body and the

Holding body is arranged, and acting as an actuator anchor plate, which is arranged on the Ankernadelabschnitt of the needle body and magnetically cooperates with the magnetic coil. The magnetic body is preferably in a central through hole in the holding body or in a central recess in the holding body, which complements the through hole and expanded in diameter, pressed. An amagnetic seal separates the nozzle body from the support body and seals the coil from a space filled with high pressure fuel.

Furthermore, due to the high-pressure fuel supplied therein, the fuel injector has in its interior a

High pressure area, in which at least the Ankernadelabschnitt the

Needle body is completely absorbed. The high-pressure fuel in principle surrounds the entire needle body, apart from the portion of the needle body, which is located within the valve seat and therefore is acted upon only by the pressure present in the combustion chamber. Accordingly, it can be said that the needle body is almost completely received in the high-pressure area. Preferably, the anchor plate is also completely accommodated in the high-pressure region. Fully absorbed in the high-pressure region here means that the respective component is in operation

Fuel injector is completely surrounded by the high-pressure fuel. The here presented fuel injector provides a simplified injector, which is provided in principle for a lower and middle pressure range and works in comparison with other known injectors of the prior art without a hydraulic coupler. The nozzle needle section, also referred to as the nozzle needle of the needle body 5, is therefore directly controlled via the armature plate of the magnet actuator, also referred to as a magnet armature, which corresponds to a true direct needle control. The anchor plate is preferably fixedly connected to the needle body at the Ankernadelabschnitt mechanically. The fuel injector according to the invention is preferably able, with the stated structure o, to supply fuel with a lower or medium pressure

Inject line pressure into the combustion chamber of the internal combustion engine.

According to a preferred further development of the fuel injector according to the invention, the latter furthermore has a spring element, preferably a spring or spiral spring, which is referred to as a so-called spring element

Return spring serves to bias the needle body against opening of the at least one injection port, so to close the injection port at an inactive magnetic actuator. The spring element is preferably arranged between a so-called spring support component and a spring plate fastened to the needle body, also called a spring plate, the spring support component being a component connected to the nozzle body, to which the needle body can move relatively. The spring plate is preferably pressed onto the needle body, more precisely on the Ankernadelabschnitt of the needle body. The spring element 5 is preferably completely received in the high-pressure region, ie

completely surrounded by high-pressure fuel, similar to the needle body and the anchor plate.

In order to allow a direct control of the needle body by the magnetic actuator against o the biasing force of the spring element, the needle body is preferably in a central through hole in the

Spring support member out. The spring support member may also have a central recess coaxial with the throughbore, whereby the spring support member is given a pot shape with a hole in the bottom forming a U-shape in cross-section. The at the Ankernadelabschnitt of the needle body attached anchor plate can be arranged open in the fuel injector according to the invention in the recess and be guided radially through the inner circumference of the recess, wherein the remainder of the needle body can be further radially guided through the through hole. In a preferred embodiment, the spring plate in

Form of a keyhole disc be formed, so in the form of a disc with a keyhole-shaped hole, which is made possible in an assembly of the fuel injector, the assembly consisting of

Anchor plate, spring support member, spring element and spring plate firmly assembled, the spring element from the needle tip side of the

Injection port sealing seat coming, so is mounted from the end of the needle body on the side of the nozzle needle section. It can already be an at least slight bias of the spring element by the

Compression by means of spring support component and spring plate can be achieved in advance. Consequently, a substantially simplified assembly is made possible because this assembly can be used as a component in the nozzle body of the fuel injector and then the remaining components can be added. A trapped construction of the combination of spring element and spring support component can be avoided.

According to a further preferred embodiment of the fuel injector according to the invention, this further comprises a separating member in the form of an amagnetic sealing ring, which is arranged between the nozzle body and the holding body, wherein the magnetic coil between the sealing ring and an inner circumference of the clamping nut, ie radially outside of the sealing ring and thus is arranged radially outside of the magnetic body and the anchor plate and radially within the clamping nut. During operation of the fuel injector, this magnetic separation serves to ensure that the magnetic flux passes through the armature plate into the inner pole, whereby stray fluxes are avoided.

Preferably, the magnetic coil is through the nozzle body, the

Holding body and the sealing ring fluid-tight separated from the high pressure area, so that no fuel reaches the solenoid and this is correspondingly in a fuel-dry area. To hold the spring support member so that it can apply the bias on the spring element is the spring support member disposed between the sealing ring and the nozzle body and is held firmly by these. This can do that

Spring support member may be kept clamped in abutment on a part of a side surface of the sealing ring between this and a recess provided in the inner periphery of the nozzle body. Accordingly, the spring element is supported on the non-magnetic sealing ring via the spring support component. This is achieved by a movement of the

Anchor plate can be moved by means of the magnetic actuator of the needle body together with the spring plate against the biasing force of the spring element, so that the injection port is released.

Further preferably, in the fuel injector according to the invention, a fuel feed to the at least one injection opening in the interior of the fuel injector centrally over each other in fluid communication

Drilled holes in the magnetic body and the anchor plate. More precisely, the fuel supply through the through-hole in the holding body, continues into a preferably central bore in the

Magnet body and finally through a bore in the anchor plate, which is arranged obliquely in the anchor plate and at the top of this centric begins, further in the vicinity of the spring element, from where the fuel can reach the injection port. The previously mentioned holding body through-hole represents in the holding body a central inlet bore, which passes through the holding body and serves to feed fuel. The central arrangement of the inlet bore has the advantage that the holding body evenly from

High pressure is applied and the inlet bore is limited over the circumference of a uniform wall thickness of the holding body, wherein the inlet bore continues through the bore in the magnetic body, which preferably also has a central inlet bore. Compared to a decentralized arrangement of the inlet bore thereby the robustness of the holding body is increased. Between an inner diameter of

Through hole in the spring support member and the outer diameter of the needle body and between the outer diameter of the spring plate and the inner diameter of the inner bore of the nozzle body may preferably be present in each case a gap that allows passage of the fuel. Alternatively, the fuel feed to the at least one

Injection opening may be performed by an external supply past the magnetic body and the armature plate, for example by respective holes in the holding body and the magnetic body, which are in fluid communication with each other, so that the fuel can penetrate into the high-pressure region. In the alternative embodiment can also between a

Inner diameter of the through hole in the spring support member and the outer diameter of the needle body and between the

l o outer diameter of the spring plate and the inner diameter of the

Inner bore of the nozzle body preferably be present in each case a gap that allows passage of the fuel.

Advantages of the invention

The injector concept according to the invention provides a simplified fuel! without hydraulic coupler, which is intended for operation in the lower and middle pressure range. The presented

Injector concept therefore offers the highest degree of component reduction.

The magnet body could also be omitted if the better soft magnetic material can be dispensed with, in which case the

Holding body would contain the geometry of the magnetic body in one piece. The elimination of the coupler reduces the necessary for complete Entschrosselung the Düsennadeldichtsitz anchor stroke, thereby eliminating a power transmission or Hubuntersetzung, which should be greater in a Tauchankerkonzept principle than in Flachankerkonzepten. For this reason, depending on the application and flat anchor concepts for magnetic actuators are conceivable, in which also the non-magnetic sealing ring could be superfluous. Due to the reduced initial air gap in the de-energized state, that is, by the reduced stroke also increases the maximum magnetic force at the beginning of the tightening phase, which in turn the switchable pressure range is increased or even one usually due to its strength requirements from a magnetic view unfavorable material existing one-piece holding body can be used , whereby the number of components even further can be reduced. Further, with the fuel injector concept of the present invention, by disposing the injector-internal components in the high-pressure region, a normally-provided low-pressure region and thus a return for the fuel can be avoided.

Brief description of the drawings

Figure 1 is a sectional view of a portion of a fuel injector according to the preferred embodiment of the invention; and

Figure 2 shows a sectional view of a fuel! Njektors according to the prior art. Preferred embodiment of the invention

The illustrated in Figure 1 fuel injector according to the preferred

Embodiment of the invention, which serves for injecting a fuel in a combustion chamber, consists essentially of a clamping nut 1 with an inner bore 11, in which a nozzle body 2 and a holding body 3 is inserted with a central through hole 31 which, for example, with the clamping nut 1 through a screw connection can be connected. Such a screw connection can be implemented, for example, by a (not shown) internal thread on the inner circumference of the inner bore 11 and a (not shown) corresponding external thread on the outer circumference of the holding body 3. Further, in the clamping nut 1, a magnetic body 51 of a magnetic actuator 5, which serves as the inner pole of the magnetic actuator 5, as well as a

Needle body 4 arranged. The liftably guided in the nozzle body 2 needle body 4 is in the preferred embodiment by a

Ankernadelabschnitt 41 and a nozzle needle portion 42 is formed. The

Lifting movement of the needle body 4 serves to release or closing of injection openings 22 through the nozzle needle portion 42 of the needle body 4, which in the nozzle body 2 at the end of an inner bore 21 of the

Nozzle body 2 are formed. To release the injection openings 22 of the nozzle needle portion 42 of the needle body 4 has a corresponding valve seat can be lifted, which is located on a side arranged on the side of the combustion chamber portion of the inner bore 21 of the nozzle body 2 on the inside thereof. In a state in which of the

Fuel injector no fuel is injected into the combustion chamber, ie in

5 a deenergized state of the magnetic actuator 5, is the

Nozzle needle portion 42 on the valve seat and separates the inner bore 21 of the nozzle body 2 from the combustion chamber. In a guide region of the nozzle needle section 42 in the inner bore 21 of the nozzle body 2, a fluid connection for conducting the fuel to be injected over

o outer peripheral side polished sections ensured that form flow channels.

The seat diameter of the nozzle needle portion 42 of the needle body 4 in the nozzle body 2 and the available magnetic force by the magnetic actuator 5 determine the maximum operating pressure of the

Inventive fuel injector. Therefore, it is advantageous to minimize the nozzle seat diameter and maximize magnetic force for the highest possible pressure range.

To actuate the nozzle needle portion 42 of the magnetic actuator 5 is provided, which in addition to the magnetic body 51 comprises an annular magnetic coil 52 o, which cooperates with an actuator acting as an anchor plate 53 which is secured to the Ankernadelabschnitt 41 of the needle body 4. The anchor plate 53, which consists for example of a magnetic material is positively connected by means of a through hole with the Ankernadelabschnitt 41 of the needle body 4, wherein the Ankernadelabschnitt 41 5 in the preferred embodiment has a smaller diameter than that

Having needle body 4 per se.

The holding body 3 has an annular end face, which is aligned with the nozzle body 2 out. The annular end face is executed in this embodiment o graded radially outward, with such a radial gradation is not a mandatory execution. The holding body 3 forms in this way, together with the inner circumference of the inner bore 11 of the clamping nut 1, an annular groove in which the magnetic coil 52 is partially received. The magnetic coil 52 is in this embodiment further in a radial groove, which is provided on5 an end face of the nozzle body 2, which to the Holding body 3 is aligned. The groove is designed here stepped radially outward, wherein such a radial gradation is also not a mandatory version. The nozzle body 2 forms in this way together with the inner circumference of the inner bore 11 of the clamping nut 1 an annular groove in which the magnetic coil 52 is partially received. To avoid magnetic leakage flux is between the nozzle body 2 and the

Holding body 3, an annular separator arranged in the form of a sealing ring 8 made of a non-magnetic or non-magnetic material. The sealing ring 8 is held clamped between the end face of the nozzle body 2 and the end face of the holding body 3 such that it is surrounded by the inner circumference of the magnetic coil 52 and this is thus arranged in an annular recess 12 through the inner circumference of the inner bore 11 of the clamping nut. 1 , the nozzle body 2, the holding body 3 and an outer periphery of the sealing ring 8 is formed. The annular recess 12 is thus separated in a fluid-tight manner from a high-pressure region 6, which is present in the interior of the fuel injector, so that the magnetic coil 52 is arranged in a dry, non-fuel impregnated region.

The magnetic body 51 is in a recess 32 of the holding body. 3

pressed, which in turn is provided in a central through hole in the holding body 3. Holes through the magnetic body 51 and through the armature plate 53 (not shown) represent the fuel flow toward the injection ports 22. The magnetic body 51 forms an inner pole of the magnetic actuator 5. In order to enable a direct actuation of the needle body 4 via the solenoid actuator 5, a spring element 7 designed as a spiral spring is further provided, which is clamped between a spring support member 71 and a spring plate 72, wherein the spring plate 72 on the

Needle body 4 is pressed. The spring support component 71 is held clamped between a shoulder provided on the inner circumference of the inner bore 21 of the nozzle body 2 and the sealing ring 8, wherein a recess 23 in the inner bore 21 of the nozzle body 2 is formed by the shoulder. The spring support member 71 has a through hole 711 for guiding the needle body 4 and a recess 712 for radially guiding the anchor plate 53. When the solenoid coil 52 is energized, the Anchor plate 53 together with the Ankernadelabschnitt 41, ie together with the needle body 4, and thus raised together with the spring plate 72 in the direction of acting as an inner pole magnetic body 51, overcomes the spring force of the spring element 7 and opens the

Injection openings 22. To end the injection process is the

Energization of the solenoid 52 completed, the spring force of the

Spring element 7, the spring plate 72 zurückdrängt and thus causes a provision of the anchor plate 53.

The energization of the solenoid coil 52 is achieved via at least one (not shown) electrical line passing through the holding body. 3

is passed and ends in an electrical connection, via which the fuel injector with a (not shown) power source is connectable. The fuel injector shown is characterized by a precise magnetic performance, which can be dispensed with a return.

Claims

claims

1. A fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, with a clamping nut (1) in which a nozzle body (2) and a holding body (3) are arranged, a needle body (4) consisting of a Ankernadelabschnitt (41) and a nozzle needle section (42) and is guided in the nozzle body (2), and recorded in the clamping nut (1) magnetic actuator (5) for direct actuation of the in an inner bore (21) of the nozzle body (2) liftably received needle body (4th ), via the lifting movement of which at least one injection opening (22) can be opened or closed, wherein the magnetic actuator (5) has a magnetic body (51), which is arranged in the holding body (3)

Magnetic coil (52) which is arranged between the nozzle body (2) and the holding body (3) and has an armature plate acting as an actuator (53), which is arranged on the Ankernadelabschnitt (41) and with the

Magnetic coil (52) cooperates, characterized in that the fuel injector has a high-pressure region (6) in which at least the Ankernadelabschnitt (41) of the needle body (4) is completely received.

2. Fuel injector according to claim 1, wherein the armature plate (53) is completely received in the high-pressure region (6).

3. A fuel injector according to claim 1 or 2, wherein the fuel injector further comprises a spring element (7), which between a

Spring support member (71) and one attached to the needle body (4)

Spring plate (72) is arranged and biases the needle body (4) against opening of the at least one injection opening (22), wherein the spring element (7) is preferably fully received in the high-pressure region (6).

4. Fuel injector according to claim 3, wherein the needle body (4) in addition to its guide in the inner bore (21) of the nozzle body (2) in addition in a through hole (711) in the spring support member (71) is guided.

5. Fuel! The injector of claim 3 or 4, wherein the anchor plate (53) is guided in a recess (712) in the spring support member (71)

is included.

6. Fuel! The injector according to any one of claims 3 to 5, wherein the spring plate (72) is a keyhole disc.

7. Fuel injector according to one of the preceding claims, wherein the fuel injector further comprises a sealing ring (8) which is arranged between the nozzle body (2) and the holding body (3), and wherein the magnetic coil (52) between the sealing ring (8). and an inner periphery of an inner bore (11) of the clamping nut (1) is arranged.

8. Fuel injector according to claim 7, wherein the magnetic coil (52) through the nozzle body (2), the holding body (3) and the sealing ring (8) is fluid-tightly separated from the high-pressure region (6).

9. A fuel injector according to claim 7 or 8, wherein the

Spring support member (71) between the sealing ring (8) and the nozzle body (2) is arranged, wherein the spring support member (71) is preferably held clamped between the sealing ring (8) and a recess (23) in the nozzle body (2).

10. Fuel injector according to one of the preceding claims, wherein a fuel inlet to the at least one injection opening (22) in the

Fuel injector is centrally via bores in the magnetic body (51) and the armature plate (53) is executed, or wherein a fuel inlet to the at least one injection port by an external feed past the

Magnet body (51) and the anchor plate (53) is executed.

A fuel injector according to any one of the preceding claims, wherein the fuel injector is capable of injecting fuel at a lower and / or average line pressure.