DE102005057953A1 - Holding down a magnet group in a fuel injector - Google Patents

Abstract

The invention relates to a fuel injector (1) for injecting fuel into a combustion chamber of an internal combustion engine. The fuel injector (1) comprises an injection valve member which releases or closes at least one injection opening for injecting the fuel and which is controlled by a solenoid valve assembly (2), the injection valve member and the solenoid valve assembly (2) being received in a central housing part (9) of an injector housing and the solenoid valve assembly (2) is supported against an upper housing part (17) of the injector housing by means of a hold-down element (31). The hold-down element is arranged below the solenoid valve assembly (2).

Description

State of technology

To the Respectively of fuel in combustion chambers of Internal combustion engines are used fuel injectors. These include an injection valve member, which at least one Injection port releases or closes over which the fuel is metered into the combustion chamber. The control the injection valve member takes place for example via a Solenoid valve assembly or a piezo actuator. For fuel injectors with solenoid valve assembly, as they are currently used, is the solenoid valve assembly at the opposite end of the at least one injection port arranged the fuel injector. The connection of the solenoid valve assembly with the injector housing takes place for example by means of a union nut. The one for the operation the solenoid valve assembly required residual air gap is doing For example, set by spacers between the solenoid valve assembly and the injector housing are included. One more way to adjust the residual air gap, the pairing loop is between Valve needle and valve body.

at Fuel injectors in which the solenoid valve assembly within the injector housing is located, this can not be bolted directly to the injector, since the height the opening in the valve body, in which the solenoid valve assembly is received and the height of the solenoid valve assembly can not be made with sufficient accuracy to a defined hold-down force maintain and thus safe operation of the fuel injector to ensure. To ensure safe operation of the solenoid valve assembly and thus the Fuel injector is the solenoid valve assembly with the help of a hold-down element, which at the at least facing away from an injection nozzle Side added between the solenoid valve assembly and the injector is against the case pressed. Suitable hold-down elements are, for example disc springs, coil springs, Corrugated rings, spring washers, O-rings or circlips.

epiphany the invention

One formed according to the invention Fuel injector for injecting fuel into a combustion chamber an internal combustion engine comprises an injection valve member, which at least one injection port for injecting the Fuel releases or closes and which of a solenoid valve assembly is controlled. The injection valve member and the solenoid valve assembly are in at least one housing part an injector housing added. The solenoid valve assembly is by means of a hold-down element against a housing part, which is arranged above the solenoid valve assembly, or against a lid, which is connected to the housing part in which the solenoid valve assembly is received, connected, supported, wherein the hold-down element is arranged below the solenoid valve assembly.

"Above" within the meaning of the invention means on the side opposite the valve seat side of the solenoid valve assembly, "below" means between Solenoid valve assembly and valve seat.

advantage the arrangement of the hold-down element below the solenoid valve assembly is that this is a smaller diameter than the solenoid valve assembly can have. This avoids collisions with a prism, which is used to clamp the workpiece for machining. By the prism the space is limited. With lower hold-down element The solenoid valve assembly can continue at the same overall height be placed above, creating a larger space for the solenoid valve assembly is achieved. Another advantage is that the solenoid valve assembly with leading upwards Pins with bottom hold down regardless of Fuel injector can be manufactured. A hold-down element, which is located above the solenoid valve assembly would due the spring tension of the trained as a plate spring hold-down element the weld the contact pins with which the solenoid valve assembly with power supplied, destroy. moreover It is advantageous that sealing elements in the solenoid valve assembly already be checked for leaks can, before the fuel injector is fully assembled.

In a preferred embodiment the hold-down element is a spring element. This makes it possible manufacturing inaccuracies balance without being dependent from the exact dimension of the opening in the injector, which houses the solenoid valve assembly, and the solenoid valve assembly different Hold-down elements or setting groups must be used. moreover By the spring element is a force on the solenoid valve assembly applied with this is placed against the Injektorgehäuse.

Prefers as spring elements are, for example disc springs or coil springs. However, it is also any other, known in the art spring element, which is designed as a compression spring, can be used.

The solenoid valve assembly comprises in a first embodiment, a magnetic pot and a magnetic disc, wherein the magnetic pot on the Magnetic disc is supported and the magnetic disk is aligned in the direction of at least one injection opening. A coil is accommodated in the magnet pot so that a magnetic field is created as soon as it is energized. The magnetic disk is preferably made of easily magnetizable material, so that the magnetic field generated by the coil is thereby amplified. By the magnetic field, an armature, which is generally formed as a plunger armature and fixedly connected to the valve member of the solenoid valve assembly, moves. As a result, a valve seat is released or closed. When the valve seat is released, fuel can flow out of a control chamber, so that the pressure in the control chamber is reduced. As a result, the injection valve member releases at least one injection opening and fuel can flow into the combustion chamber. As soon as the energization of the coil is stopped, the magnetic field breaks down and the valve member is placed in its seat. The connection from the control chamber is closed. Via a fuel supply line, pressurized fuel flows into the control room. As a result, the injection valve member is placed in its seat and closed at least one injection port. Instead of the three-part solenoid valve assembly with magnet pot, magnetic disk and armature designed as a plunger anchor, it is also conceivable that the solenoid valve assembly is formed in two parts in a second embodiment. In this case, the solenoid valve assembly includes a magnet pot and an armature formed as a flat armature. A magnetic disk is not provided in this embodiment.

Of the formed according to the invention Fuel injector is in auto-ignition internal combustion engines both in high-pressure accumulator injection systems (common rail) as also with pump-nozzle systems used. Unlike the common rail system, where the injection of the fuel is triggered by releasing the valve seat is in pump-nozzle systems the injection by closing the valve seat triggered.

In an embodiment is additional between the hold-down element and the solenoid valve assembly Compensating element added. It is also possible between the solenoid valve assembly and the hold-down element to provide a washer around the Magnetic material, generally a powder composite material with low mechanical Strength against occurring edge loads caused by the hold-down element imprinted can be to protect.

drawing

In the following the invention will be described in more detail with reference to a drawing:
It shows:

1 a detail of a fuel injector with solenoid valve assemblies according to the prior art,

2 a schematic representation of a solenoid valve assembly according to the prior art,

3 a schematic representation of a recorded in a fuel injector solenoid valve assembly,

4 a section of a fuel injector with incorporated therein solenoid valve assembly according to the invention.

embodiments

1 shows a section of a fuel injector with incorporated therein solenoid valve assembly according to the prior art.

A fuel injector 1 includes a solenoid valve assembly 2 , about which a in 1 not shown injection valve member is driven. The solenoid valve assembly 2 includes a magnet pot 3 in which a coil 4 is included. To the magnet pot 3 closes a magnetic disk 5 at. In the magnetic disk 5 is a central hole 6 formed, in which a valve piston 7 is movably received.

The solenoid valve assembly 2 including the valve piston 7 is in a recess 8th in a middle housing part 9 of the fuel injector 1 added. From the recess 8th extends a hole 10 in the direction of the injection valve member. In the hole 10 is the valve piston 7 guided. The hole 10 opens into a control room 11 which can be closed or released by an edge 13 on the valve piston 7 in a seat 12 is made or is lifted from this.

With energized coil 4 A magnetic field forms, which passes through the magnet pot 3 and the magnetic disk 5 is reinforced. The developing magnetic field becomes an anchor 14 that with the valve piston 7 firmly connected, in the direction of the magnetic disk 5 emotional. Once the energization of the coil 4 is terminated, the magnetic field also rises. With the help of a spring element 15 , which is preferably a compression spring designed as a helical spring, becomes the valve piston 7 back out of the seat 12 lifted. The power supply of the coil 4 takes place via a plug connection 16 about which the fuel injector 1 is connected to the voltage network of the motor vehicle. The magnet pot 3 and the magnetic disk 5 are preferably made of a soft magnetic material with high saturation induction and preferably with made of high electrical resistivity.

The recess 8th with the incorporated therein solenoid valve assembly 2 is through an upper housing part 17 locked. To move the solenoid valve assembly 2 inside the recess 8th to prevent is in the known from the prior art fuel injectors 1 between the solenoid valve assembly 2 and a lower end surface 18 of the upper housing part 17 a hold-down element 19 added. In the in 1 The embodiment shown is the hold-down element 19 a plate spring.

At the upper housing part 17 opposite side of the middle housing part 9 closes a lower housing part 20 at. In the lower housing part 20 are formed injection openings, not shown here. Furthermore, in the lower housing part 20 the injection valve member, with which the at least one injection port is closed or released, out. To control the injection valve member is in the lower housing part 20 a second control room 21 formed, in which a spring element 22 is received, which is preferably designed as a compression spring coil spring. The spring element 22 acts on an upper end face of the injection valve member. The connection of the lower housing part 20 with the middle housing part 9 and the upper housing part 17 done with the help of a clamping nut 23 ,

Around the interior of the fuel injector 1 To seal against the environment is in a groove 24 in the upper housing part 17 a sealing element 25 , preferably an O-ring, added. The sealing effect is achieved in that the sealing element 25 against an inner surface 26 the clamping nut 23 is pressed. This will prevent moisture or debris from entering the fuel injector from the outside 1 can penetrate. At the same time it prevents fuel from the fuel injector 1 get to the environment.

2 shows a schematic representation of a solenoid valve assembly, as installed in the prior art in a fuel injector.

In the recess 8th in the middle housing part 9 , from which the bore 10 extends, is the solenoid valve assembly 2 added. The solenoid valve assembly 2 includes the magnet pot 3 with the recorded therein, not shown here coil 4 and the magnetic disk 5 , When energizing the coil 4 A magnetic field forms, which passes through the magnet pot 3 and the magnetic disk 5 is reinforced. This will be the anchor 14 in the direction of the magnetic disk 5 moves until the valve piston 7 at which the anchor 14 is secured without play, with the edge 13 in the seat 12 stands. The distance between it and the magnetic disk 5 and one of the magnetic disc 5 facing lower end face 27 of the anchor 14 is set as residual air gap 28 designated. Through the residual air gap 28 will avoid the anchor 14 on the magnetic disk 5 hits. This could lead to a rebound of the anchor 14 and thus a reopening of the seat 12 come, which causes the injection valve member releases the at least one injection port again and further fuel enters the combustion chamber of the internal combustion engine, whereby the combustion process is adversely affected. On the other hand, it is possible that the bouncing mechanical damage occurs. Once the energization of the coil 4 is switched off and thus the solenoid valve is released, the valve piston 7 with the help of in 2 not shown spring element 15 from the seat 12 lifted. The way the valve piston 7 in the axial direction can be covered by the upper housing part 17 limited. This way, the valve piston 7 travels between open and closed position is the hub 29 , To avoid the solenoid valve assembly 2 within the recess 8th shifts, this is with the help of the hold-down element 19 , which is designed here as a plate spring, held in place. For this purpose, the hold-down element acts 19 on one of the upper housing part 17 facing end face 30 of the magnet pot 3 and the lower end face 18 of the upper housing part 17 ,

3 shows a schematic representation of the central housing part with therein received solenoid valve assembly according to the invention.

Also in the inventive solution is the solenoid valve assembly 2 holding the magnet pot 3 and the magnetic disk 5 includes in the recess 8th in the middle housing part 9 added. According to the invention, a hold-down element 31 between an end face 32 the recess 8th and the magnetic disk 5 added. The hold-down element 31 is also in the in 3 illustrated embodiment, a plate spring. Ne Ben the disc spring, however, is also any other, known in the art as a compression spring spring element used.

The hub 29 of the valve piston 7 is also in the inventive solution through the upper housing part 17 limited. To the residual air gap 28 through which a rebound of the valve piston 7 is avoided, is the anchor 14 in the inventive solution further up the valve piston 7 attached as known from the prior art. That means that the distance between the anchor 14 and the edge 13 who are in the seat 12 is greater in the inventive solution than in known fuel injectors. Unless the distance between the anchor 14 and the edge 13 is chosen to be the same size as in known fuel injectors, the solution according to the invention a smaller distance between the valve seat 13 and face 32 the recess 8th or the upper housing part 17 achieved, resulting in a more compact design of the fuel injector 1 leads.

An advantage of the solution according to the invention is that for adjusting the residual air gap 28 and hub 29 the solenoid valve assembly 2 including valve piston 7 already in the middle housing part 9 can be pre-assembled. It is also possible, the hold-down element 31 to manufacture in a smaller diameter. This will be the hold-down element 31 not on the outer edge of the solenoid valve assembly 2 , but mechanically favorable in the area of the center circle of the magnet pot 3 arranged. Another advantage is that by the arrangement of the hold-down element 31 below the solenoid valve assembly 2 the upper housing part 17 and their contact with the coil and the contact pins 33 (shown in 4 ) firmly connected, eg welded, can be. In this way, a pre-assembled unit can be produced, which then with the lower housing part 20 can be connected.

4 shows a section of a fuel injector with inventively incorporated therein solenoid valve assembly.

The solenoid valve assembly 2 includes the magnet pot 3 , with incorporated therein coil 4 and the magnetic disk 5 , To generate the magnetic field, the coil 4 via contact pins 33 powered. The connection to an external power source, which in 4 is not shown, takes place in that the contact pins 33 through openings 34 in the upper housing part 17 be led to the outside. To avoid moisture or other substances from the environment, which has a negative impact on the function of the fuel injector 1 can have in the fuel injector 1 is in the openings 34 each a sealing element 35 recorded by wel Ches the pins 33 be passed. The sealing element 35 is in a preferred embodiment an O-ring. However, it is also possible to use any further sealing element known to the person skilled in the art. For further sealing against the environment is on the upper housing part 17 a lid 36 placed. The lid 36 is preferably made of plastic. In a preferred embodiment, the lid made of plastic 36 directly on the upper housing part 17 sprayed. This will be a firm connection of the lid 36 with the upper housing part 17 reached, since the lid 36 then the contour of the upper housing part 17 exactly fits. As a result, a good seal against the environment is achieved. For further sealing against the environment is between the upper housing part 17 and the middle housing part 9 another sealing element 37 added. The sealing element 37 is preferably an O-ring, but it is also any other, known in the art sealing element used.

To the solenoid valve assembly 2 to hold in place and movements in the solenoid valve assembly 2 To avoid this is done with the help of the hold-down element 31 , which is below the solenoid valve assembly 2 between the face 32 the recess 8th and the solenoid valve assembly 2 is arranged, against the lower end face 18 of the upper housing part 17 pressed. The spring force of the preferably designed as a plate spring hold-down element 31 must be chosen so that even with rapid movement of the valve piston 7 a bouncing of the anchor 14 on the magnetic disk 5 is avoided. In addition, the hold-down element must 31 The solenoid valve assembly also hold against the mass forces that occur during a shaking, in their position. To larger manufacturing inaccuracies in the production of the recess 8th It is possible to balance between the hold-down element 31 and the magnetic disk 5 a compensation element 38 to arrange. The height 39 of the compensating element 38 depends on the desired spring force of the hold-down element 31 in the installed state. In addition to the training of Niederhalterelementes 31 as a diaphragm spring can hold-down element 31 also be any other, known in the art spring element. For example, a helical spring designed as a compression spring is also used as a hold-down element 31 suitable. Furthermore, corrugated rings, spring washers, O-rings or snap rings as hold-down element 31 suitable.

Another advantage of the solution according to the invention, in which the hold-down element 31 below the solenoid valve assembly 2 is arranged, that is a connector assembly, which is the upper housing part 17 with lid 36 , The built-in therein and welded with outwardly projecting contacts pins 33 and the coil 4 comprehensive connector assembly can be made separately. This makes it possible to obtain this module as a foreign reference part and thereby save costs. When arranging the hold-down element 31 above the solenoid valve assembly, between the magnet pot 3 and the upper housing part 17 Otherwise, if the connector assembly is made separately, the welds may break with which the contact pins 33 connected to the outwardly projecting contacts. As a result, the Ste so damaged that fuel injector operation 1 is no longer possible. Another advantage of making the connector assembly separately is that the sealing elements can be inspected separately for leaks. This can save costs in quality assurance.

The connection of the lower housing part, not shown here 20 with the middle housing part 9 and the upper housing part 17 takes place in the inventively designed fuel injector as well, as already known from the prior art, preferably with a clamping nut 23 , in the 4 also not shown. Instead of the clamping nut 23 is also the connection of the housing parts 9 . 17 . 20 possible by screwing with screws. In this case, it is preferably in the lower housing part 20 or in the upper housing part 17 formed at least one thread, while the remaining housing parts are provided with corresponding holes through which each screw can be guided, which are then screwed into the thread.

Claims (7)

A fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising an injection valve member, which releases or closes at least one injection opening for injecting the fuel, and which of a solenoid valve assembly ( 2 ), wherein the injection valve member and the solenoid valve assembly ( 2 ) in at least one housing part ( 9 ) of an injector housing and the solenoid valve assembly ( 2 ) by means of a hold-down element ( 31 ) against a housing part, which above the solenoid valve assembly ( 2 ) is supported, or against a cover, which is connected to the housing part, in which the solenoid valve assembly is received, is supported, characterized in that the hold-down element ( 31 ) below the solenoid valve assembly ( 2 ) is arranged. Fuel injector according to claim 1, characterized in that the hold-down element ( 31 ) is a spring element. Fuel injector according to claim 2, characterized that the spring element is a plate spring. Fuel injector according to claim 2, characterized that the spring element designed as a compression spring coil spring is. Fuel injector according to one of claims 1 to 4, characterized in that the solenoid valve assembly ( 2 ) a magnetic pot ( 3 ) with coil incorporated therein ( 4 ) and a magnetic disk ( 5 ), wherein the magnet pot ( 3 ) on the magnetic disk ( 5 ) and the magnetic disk ( 5 ) is aligned in the direction of the at least one injection opening. Fuel injector according to claim 5, characterized in that the hold-down element ( 31 ) with one side against the magnetic disk ( 5 ) and supported with the other side against the injector. Fuel injector according to one of claims 1 to 6, characterized in that between the hold-down element ( 31 ) and the solenoid valve assembly ( 2 ) a compensation element ( 38 ) is recorded.