DE10317149A1 - Fuel injection valve for direct injection of fuel into combustion chamber of internal combustion engine, has spring biasing valve pin part comprising piezoelectric, electrostrictive or magnetostrictive element - Google Patents

Abstract

A valve pin (3) is operatively connected to an excitable electromagnetic operating device. One or more parts of the valve pin are formed as an excitable piezoelectric, electrostrictive or magnetostrictive element (38). A spring biases a valve closing body (4) against the element.

Description

State of technology

The Invention is based on a fuel injector according to the Genus of the main claim.

For example, from the DE 199 37 961 A1 a fuel injector with a valve needle is known, which is actuated by an electromagnetic actuator. This fuel injection valve can advantageously be used, for example, in engines with very high outputs, large combustion chamber volumes and / or supercharged engines, since the magnetic actuation permits long actuation paths without great structural expenditure and large fuel flows can thus be easily achieved.

adversely in the fuel injector known from the above-mentioned documents in particular that the at the respective fuel injection metered fuel quantities for many Areas of application cannot be dosed with sufficient accuracy. Also respond electro-magnetic actuators only delayed on actuation signals, since in particular the build-up of a magnetic field is not arbitrary in time shortened can be. The course of the fuel quantity over the course of time an injection process is almost entirely of the structural characteristics dependent of the fuel injector and can for example while the operation of the fuel injector is very inadequate changed become.

Advantages of invention

The fuel injector according to the invention in contrast, with the characteristic features of the main claim Advantage that under Maintaining the said advantage, fuel metered very precisely can be. Moreover Is it possible the flow curve of the fuel advantageously within an injection process influence or control, even during operation and in particular between two consecutive injection processes.

By those in the subclaims listed activities are advantageous developments of the specified in the main claim Fuel injector possible.

In A first further development is the piezoelectric, electrostrictive or magnetostrictive element arranged between the valve needle and valve closing body. The element can be thereby particularly advantageously removed and decoupled from the electro-magnetic confirmation means Arrange.

In a further development of the fuel injector according to the invention a spring element biases the valve closing body against the element. The element can therefore be in constant investment to the valve closing body or the valve needle. Elaborate and strong mechanical forces exposed joints between the element and the valve closing body or the valve needle can thus easier, more reliable and stronger be trained to be resilient.

Of Another advantage is if the item is independent excitable by the electromagnetic confirmation device or actuatable is. The closing and opening behavior of the element can thereby better on the closing and opening behavior the electro-magnetic actuator to achieve a desired closing or opening behavior of the fuel injector.

Advantageous it is also when fuel flows radially around the element. The element can thus be cooled in a simple manner.

moreover it is beneficial if the length the valve needle adjustable by the energized state of the element is, in particular continuously or over more than two stages. The opening and closing operations of the Fuel injection valves can be even better in this way to the respective requirement regarding injection quantity, injection timing and optimize the injection process.

By an actuator module forming the element with a piezoelectric Actuator, a spring body and an actuator housing with an actuator head and an actuator foot, the element can be particularly stable, build compact and easy to assemble.

Farther the actuator module can be constructed in a particularly simple, reliable and compact manner when the actuator housing has a flexible section and / or the spring body Radially surrounds actuator.

is the actuator housing at least partially with a good thermal and electrical insulating liquid filled, so the heat dissipation and even heat distribution be improved.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. It shows gene:

1 2 shows a schematic section through an exemplary embodiment of a fuel injection valve according to the prior art,

2 a schematic section through a first embodiment of the fuel injector according to the invention in the region of the sealing seat and

3 a schematic section through a second embodiment of the fuel injector according to the invention in the region of the sealing seat.

description of the embodiments

Exemplary embodiments of the invention are described below by way of example. Matching components are provided with matching reference numerals in the figures. However, before using the 2 and 3 preferred embodiments of the invention will be explained in more detail with reference to 1 a conventional fuel injector 1 briefly explained in its essential components for a better understanding of the invention.

This in 1 illustrated embodiment of a fuel injector 1 according to the prior art is in the form of a fuel injector 1 designed for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines. The fuel injector 1 is particularly suitable for injecting fuel directly into a combustion chamber (not shown) of an internal combustion engine.

The fuel injector 1 consists of a nozzle body 2 , in which a valve needle 3 is arranged. The valve needle 3 stands with a valve closing body 4 in operative connection with one on a valve seat body 5 arranged valve seat surface 6 cooperates to form a sealing seat. At the fuel injector 1 in the exemplary embodiment, it is an inward opening fuel injector 1 which has a spray opening 7 features. The nozzle body 2 is through a seal 8th against an external pole 9 a solenoid 10 sealed.

The solenoid 10 is in a bobbin case 11 encapsulated and on a bobbin 12 wound, which on an inner pole 13 the solenoid 10 is applied. The inner pole 13 and the outer pole 9 are due to a narrowing 26 separated from one another and to one another by a non-ferromagnetic connecting component 29 connected. The solenoid 10 is over a line 19 from one via an electrical plug contact 17 supplyable electric current excited. The plug contact 17 is from a plastic coating 18 surround that at the inner pole 13 can be molded. The outer pole 9 who have favourited Solenoid 10 , the bobbin case 11 , the bobbin 12 , the inner pole 13 and an anchor 20 form an electromagnetic confirmation device.

The valve needle 3 is in a valve needle guide 14 led, which is disc-shaped. A paired adjusting disc is used for stroke adjustment 15 , On the other side of the shim 15 is the anchor 20 , This is above a first flange 21 non-positive with the valve needle 3 connected by a weld 22 with the first flange 21 connected is. On the first flange 21 a return spring is supported 23 from which in the present design of the fuel injector 1 through a sleeve 24 is brought under tension.

In the valve needle guide 14 , at anchor 20 and on a guide element 36 run fuel channels 30 . 31 and 32 , The fuel is supplied via a central fuel supply 16 fed and through a filter element 25 filtered. The fuel injector 1 is through a seal 28 against a fuel rail, not shown, and through a further seal 37 sealed against a cylinder head, not shown.

On the spray side of the anchor 20 is an annular damping element 33 , which consists of an elastomer material, arranged. It lies on a second flange 34 on which over a weld 35 cohesively with the valve needle 3 connected is.

In the idle state of the fuel injector 1 becomes the anchor 20 from the return spring 23 acted against its stroke direction so that the valve closing body 4 on the valve seat 6 is kept in a sealing system. When the solenoid is excited 10 this builds up a magnetic field, which is the anchor 20 against the spring force of the return spring 23 moved in the stroke direction, the stroke by a in the rest position between the inner pole 12 and the anchor 20 working gap 27 is specified. The anchor 20 takes the first flange 21 which with the valve needle 3 is welded, also in the stroke direction. The one with the valve pin 3 related valve closing body 4 lifts from the valve seat 6 and the fuel will flow through the spray port 7 hosed.

If the coil current is switched off, the armature drops 20 after sufficient reduction of the magnetic field by the pressure of the return spring 23 from the inner pole 13 from which the valve needle 3 related first flange 21 opposite the stroke direction moves. The valve needle 3 is thereby moved in the same direction, causing the valve closing body 4 on the valve seat 6 touches down and the fuel injector 1 is closed.

2 shows a schematic section through a first embodiment of the fuel injector according to the invention 1 in the area of the valve closing body 4 , The element 38 is in this embodiment as part of the valve needle 3 between the spray end of the valve needle 3 and the end of the valve closing body remote from the spray 4 arranged coaxially, the element 38 and the valve closing body 4 into a spray side in the spray opening 7 mouth opening 39 of the valve seat body 5 intervention.

The element 38 has a round cylindrical shape in this embodiment. The piezoelectric element in this embodiment 38 is excited via electrical connections, not shown, the element 38 , depending on the arousal, shortened or lengthened. The arousal of the element 38 can be made regardless of excitation of the electromagnetic confirmation device 1 respectively. For example, it is possible with the fuel injector already opened by the electromagnetic confirmation device 1 to further increase or decrease the flow and thus to adapt the flow of fuel more precisely to the requirements of the respective state of the combustion process.

3 shows a schematic section through a second embodiment of the fuel injector according to the invention 1 in the area of the sealing seat, similar to the first embodiment of the invention 2 , The element 38 is in this embodiment by an actuator module 45 educated.

The actuator module 45 points inside an actuator housing 44 an actuator 40 and a tubular spring body 41 on, the substantially round cylindrical actuator housing 44 an actuator foot 42 and an actuator head 43 having. The upstream side of the actuator 40 arranged actuator foot 42 is with the upstream side of the actuator foot 42 arranged part of the valve needle 3 added, for example by material closure. Downstream of the actuator 40 is the actuator head 43 between the actuator 40 and the spherical valve closing body, which is circular segment-shaped in cross section 4 arranged. The valve closing body 4 is, for example, by material connection with the actuator head 43 together. In other embodiments of the fuel injector according to the invention 1 the valve closing body 4 against the actuator module 45 or the element 38 and the upstream part of the valve needle 3 be biased by a spring element. The actuator housing 44 which is the actuator 40 hermetically surrounds, has in its radial direction the actuator 40 circumferential walls an in this embodiment substantially bellows-shaped flexible section 46 on.

A spring body 41 which is inside the actuator housing 44 is arranged and the actuator 40 radially surrounds, is the inflow on the inside of the actuator housing 44 pointing side of the actuator foot 42 and downstream on the inside of the actuator housing 44 facing side of the actuator head 43 added, for example by welds, not shown. The spring body 41 tensions the actuator 40 over the actuator foot 42 and the actuator head 43 in front.

The Invention is not limited to the illustrated embodiments and z. B. also for after Outside opening Fuel injector suitable.

Claims (13)

Fuel injector ( 1 ), in particular for the direct injection of fuel into a combustion chamber of an internal combustion engine, with a valve needle ( 3 ) that have a valve closing body ( 4 ) with a valve seat surface ( 6 ) on a valve seat body ( 5 ) is configured, cooperates to form a sealing seat and an injection opening provided downstream of the sealing seat ( 7 ), the valve needle ( 3 ) with an excitable, electro-magnetic confirmation device ( 9 - 13 . 20 ) is in operative connection, characterized in that part or more parts of the valve needle ( 3 ) as an excitable piezoelectric, electrostrictive or magnetostrictive element ( 38 ) are executed. Fuel injection valve according to Claim 1, characterized in that the at least one piezoelectric, electrostrictive or magnetostrictive element ( 38 ) between part of the valve needle ( 3 ) and the valve closing body ( 4 ) is arranged. Fuel injection valve according to claim 2, characterized in that a spring element the valve closing body ( 4 ) against the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) preloaded. Fuel injection valve according to one of the preceding claims, characterized in that the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) can be excited or actuated independently of the electromagnetic actuating device. Fuel injection valve according to one of the preceding claims, characterized in that that the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) around which fuel flows radially. Fuel injection valve according to one of the preceding claims, characterized in that the excited state of the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) the length of the valve needle ( 3 ) is adjustable. Fuel injection valve according to Claim 6, characterized in that the excited state of the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) comprises more than two states, which can be adjusted in steps or steps. Fuel injection valve according to one of the preceding claims, characterized in that the piezoelectric, electrostrictive or magnetostrictive element ( 38 ) by an actuator module ( 45 ) with an actuator ( 40 ), at least one spring body ( 41 ) and an actuator housing ( 44 ) with an actuator foot ( 42 ) and an actuator head ( 43 ) is formed. Fuel injection valve according to Claim 8, characterized in that the actuator housing ( 44 ) at least one flexible section ( 46 ) having. Fuel injection valve according to Claim 8 or 9, characterized in that the at least one spring body ( 41 ) the actuator ( 40 ) radially surrounds. Fuel injection valve according to one of Claims 8 to 10, characterized in that the actuator ( 40 ) between the actuator head ( 43 ) and the actuator foot ( 42 ) by the at least one spring body ( 41 ), which on the actuator head ( 43 ) and on the actuator foot ( 42 ) attacks, is clamped or preloaded. Fuel injection valve according to one of Claims 8 to 11, characterized in that the actuator housing ( 44 ) the actuator ( 40 ) hermetically sealed. Fuel injection valve according to one of Claims 8 to 12, characterized in that the actuator housing ( 44 ) is at least partially filled with an electrically non-conductive liquid with good thermal conductivity.