DE19945673B4 - Injection nozzle for internal combustion engines with a measuring element and a pressure-tight electrical feedthrough - Google Patents

Abstract

Injector for internal combustion engines, with a housing (81) having one or more injection ports (83), a Interior (84) for supplying fuel to the injection openings (83) and a measuring element (50) which is arranged in the interior space (84) to the fuel flow and / or another state parameter of the fuel, wherein the measuring element (50) by a pressure-tight electrical feedthrough (9) in the housing (81) of the injector (80) with the outside space is connected, characterized in that the electrical feedthrough (9) consists of several layers (11, 12, 13), each one or multiple vias (21, 22, 23), wherein the vias (21, 22, 23) of two adjacent layers are arranged offset from each other and the electrical feedthrough (9) lateral conductor tracks (31, 32), which in the individual Layers (11, 12, 13) located through-contacts (21, 22, 23) to a continuous line element (20) connect.

Description

The The present invention relates to an injection nozzle for internal combustion engines according to the preamble of claim 1

at the combustion of a fuel-air mixture is special important to have a fine distribution of fuel for example Gasoline, diesel or kerosene, with the necessary combustion air is reached. This is achieved by injectors that control the fuel finely distributed and in the necessary amount to the combustion chamber of an engine. A such injection nozzle is in an article by Zexel Corporation in the AMAA conference proceedings (ISBN 3-540-64091-6) P. 233.

at the known injection nozzles or injectors is the amount of fuel to be injected with every injection by a precise as possible prior calibration of injector or injector specified. It is thus already determined during the production of the injection nozzle, what amount of fuel in an injection pulse or injection process gets into the combustion chamber. Due to manufacturing tolerances arise However, fluctuations in the injection quantity at an injection between the injection nozzles produced.

Around especially big Deviations from the normal value are avoided, a separation takes place the injectors concerned during production, which results in high costs. Furthermore is the calibration relatively expensive. On top of that, no individual characteristic curve for each Injector is present after production. Therefore varies in operation the injection quantity from injector to injector, as well as from one Injection process to the next. The accuracy of the injection quantity is therefore limited.

At the Operation of the engine has the limited accuracy of injection quantity result in an increased There is a risk of poor mixture formation, i. h. that that Mixing ratio between Fuel and air unfavorable is. One consequence of this is that some of the fuel is unburned Combustion chamber leaves and harmful Exhaust gases generated. Furthermore, results in an unfavorable mixing ratio poorer efficiency of the internal combustion engine.

In the generic patent DE 195 81 786 C1 discloses a fuel injector having sensors that measure state parameters of the fuel supplied from the fuel pump. The signals coming from the sensors are input to a control unit of the fuel injection valve. The control unit processes the signals and controls the actuators of the fuel injection valve, whereby the injection quantity can be adjusted. The sensors are located near the fuel inlet of the fuel injection valve. The disadvantage is that the state parameters such as the pressure of the fuel are not measured directly at the injection nozzle of the fuel injection valve and thus do not reflect the state of the fuel at the injection openings.

The US 4,432,228 A discloses an injection nozzle whose measuring element is arranged in a fuel supply of the injection nozzle in front of its front end with injection openings. The electrodes of the measuring element are guided via a simply sealed passage to a measuring device outside the injection nozzle. The disadvantage here is that the state of the fuel at the injection openings can not be reproduced and the electrical implementation is not suitable for high fuel pressures.

The DE 1 161 969 A discloses an arrangement for positioning and sealing electrical conductors in an electrical feedthrough, wherein the electrical conductors are each cast with a z-shaped bent portion in the electrical feedthrough. The disadvantage here is that the electrical implementation is not suitable for high pressures.

It is therefore the object of the present invention, an injection nozzle for an internal combustion engine to create, with the injection quantity determined with increased accuracy or can be set and this a pressure-tight electrical feedthrough for a measuring element immediately in front of the injection openings the injector provided.

A injection for internal combustion engines includes a housing, the one or more injection ports and a movable valve needle, wherein the valve needle the injection openings free and an interior space between the housing and the valve needle for Supply of fuel to the injection openings, wherein in the interior of the injection a measuring element is arranged around the fuel flow and / or to measure another conditional parameter of the fuel. Thereby can for every injector individually the actual Injection quantity during the respective injection can be determined directly at the injection openings. By Measurements of other fuel condition parameters, such as Pressure or temperature, the combustion process can be even further be optimized. The measuring element in the interior is characterized by a pressure-tight electrical implementation in the case the injector with the outside space connected.

The electrical implementation the injection nozzle according to the invention is made composed of several layers, each one or more vias , wherein the plated-through holes of two adjacent layers offset from one another and the electrical feedthrough lateral Tracks, which are located in the individual layers Connect vias to a continuous line element. As a result, a particularly high compressive strength in the field of electrical conduction reached.

Prefers is the measuring element to a control loop for controlling the injection quantity coupled. This will be a feedback Sensor actuator system achieved, creating a direct, immediate Optimization of the injected fuel quantity according to the current requirements can be made.

Prefers the lateral tracks run between adjacent ones Layers. As a result, the pressure is not on the individual vias, but will over the layer surfaces distributed.

advantageously, includes the electrical feedthrough a ceramic separator made e.g. layered or multilayered is designed. In the individual layers can be one or more continuous holes be arranged, which provided with an electrically conductive material are. For example, a metal paste can be introduced in the through holes be. This results in a simple and inexpensive production, e.g. using batch processing, but still a high degree of miniaturization the electrical implementation achieved at high strength.

Preferably is the electrical feedthrough made of ceramic in green tape technology. The individual layers have e.g. a thickness of 10 to 100 microns, preferably 60 to 100 microns, and in particular about 80μm. These measures will a particularly rational cost-effective production at a achieved very small construction and yet high strength.

The Measuring element can e.g. be a pressure sensor with a membrane and / or exist as strain gauges.

following the present invention will be described with reference to the drawings, in which

1 an injection nozzle according to a preferred embodiment of the invention;

2 a longitudinal section through the front area of in

1 shown injection nozzle according to the invention shows;

3 shows the measuring element and the electrical feedthrough of the injection nozzle according to the invention in an exploded view;

4 schematically shows the measuring element and the electrical feedthrough as a sectional view;

5 a schematic sectional view through the electrical feedthrough in the housing of the injection nozzle shows.

1 shows an injection nozzle 80 for an internal combustion engine with a pressure-tight electrical feedthrough 9 , The electrical implementation 9 extends through an area of the housing 81 the injector 80 in their interior. There is a sensor attached, with which the fuel flow inside the injector 80 measured over outside lines 82 becomes the inside of the injector 80 located sensor powered. The measurement signals obtained are in operation via lines 82 fed to a control loop which controls the injection quantity of the fuel or the opening of the injection valve. In the interior of the injector 80 , which is traversed by the fuel, prevails z. B. a pressure of about 1500 bar, which withstands the electrical feedthrough.

Of course, other types of sensors in the interior of the injection nozzle 80 possible, which can measure various parameters, such as the pressure or the temperature of the fuel. By means of the electrical feedthrough according to the invention, the respective sensor is electrically connected to the outside space for passing on the measuring signals and / or for the power supply.

2 shows a longitudinal section through the front portion of the injection nozzle 80 with the electrical feedthrough 9 , The cylindrical housing 81 the injector 80 at its front end several injection ports 83 , Inside the case 81 there is a movable valve needle 90 for injecting fuel into the combustion chamber of the engine, the injection ports 83 free. For this purpose, the valve needle is at every injection 90 in the direction of arrow B moves upward so that the needle tip lifts off the needle seat and fuel from the interior 84 through the injection openings 83 is pushed out. The fuel is inside 84 between the housing wall 81 and the valve needle 90 the injector 80 ,

The pressure-tight electrical feedthrough 9 is located in an area of the housing wall 81 and forms a pressure-tight closure, allowing under the high pressure in the interior 84 the injector 80 no fuel can flow through the electrical feedthrough to the outside. In the interior 84 the injector 80 is a measuring element as a sensor 50 arranged to measure the flow of fuel through the injector 80 serves.

In another embodiment the invention is in the housing arranged a membrane, with a strain gauge attached to the outside is to measure the pressure.

In 3 is the pressure-tight electrical feedthrough with the connected sensor or measuring element 50 shown in an exploded view. It includes several ceramic layers 11 . 12 . 13 , which are stuck together or connected. The layers 11 . 12 . 13 are in a cylindrical cavity 61 in a housing or frame 60 , which is also cylindrical in shape, is formed. On the viewer facing the bottom of the ceramic layer 11 are two tracks 31 applied laterally extending along the layer boundary. Every trace 31 connects a line section 22 passing through the middle layer 12 extends, with a staggered arranged line section 21 that goes through the first layer 11 extends (see 4 ).

The pipe sections 22 are, as in 4 recognizable, again in each case with a further conductor track 32 connected, focusing on the adjacent layer 13 located. The course of the two line elements 20 with their associated cable sections 21 . 22 . 23 and lateral line sections or conductor tracks 31 . 32 is in 4 shown. Between the pipe sections 21 and 22 such as 22 and 23 each conduit element 20 there is a lateral offset that passes through the respective track 31 . 32 is bridged.

The firmly connected layers ( 11 . 12 . 13 ) made of ceramic together form a separating element 10 , On the outside of the separator 10 or the outer layer 13 is the measuring element 50 , which is formed by a conductor or a wire or metal wire, which on the separator 10 is arranged. With the measuring element 50 For example, a flow measurement in a flowing medium can be carried out by measuring the electrical resistance of the conductor track. This resistance is known to be temperature dependent and thus changes depending on the flow or flow rate of the flowing medium. About the heating power and the ohmic resistance of the fuel flow is measured.

Based on 5 Below is the structure of the electrical implementation 9 the injector 80 described in more detail. The electrical passage shown in section shows the separator 10 made of insulating material that comes from the layers 11 . 12 . 13 is constructed or manufactured. The layers 11 . 12 . 13 are ceramic layers that are aligned parallel to each other and are firmly connected to each other at the layer boundaries. There is a section in each layer 21 . 22 . 23 a conduit element 20 that has an electrical connection between the top 10a and the bottom 10b represents the separating element. The sections 21 . 22 . 23 of the conduit element 20 are offset from each other and through the lateral tracks 31 . 32 connected with each other. On the top 10a and the bottom 10b of the separating element 10 is in each case a contact pad or contact element 30a . 30b which consists of a metallic layer and as a connection for electrical elements on both sides of the separating element 10 serves.

The pipe sections 21 . 22 . 23 are formed by metals or metallizations, which are in through holes in the ceramic layers 11 . 12 . 13 are formed. In the preferred embodiment shown here, the through holes or via holes are filled with a metal paste. But it is also possible that the holes are metallized in each case only at its edge or on its inner wall to the electrically conductive connection between the top and bottom 10a . 10b of the separating element 10 to build.

The holes that line the metallization with the sections 21 . 22 . 23 form perpendicular to the planes of the layers 11 . 12 . 13 , The mutual offset from one section to the next is lateral ie it runs parallel to the layer planes. Every section 21 . 22 . 23 extends through a layer 11 . 12 . 13 so that the offset occurs at the layer boundaries, respectively. Every section 21 . 22 . 23 forms a via in the respective layer 11 . 12 . 13 ,

The tracks 31 . 32 are metal layers or tracks, which are vapor-deposited or printed on the respective top and / or bottom of the respective layer. The tracks 31 . 32 are very compact or designed small and usually have a thickness of 10 to 20μm. But they can also be designed substantially thinner, for example, with a thickness of 1 micron or less.

The from the individual sections 21 . 22 . 23 or vias and traces 31 . 32 formed line elements 20 run zigzag through the separator 10 , In the in 5 The portion of the electrical feedthrough shown are for simplicity only two Leitungselemen th 20 represented by three adjacent ceramic layers 11 . 12 . 13 run. However, it can also be three, four or much more line elements 20 be provided in the pressure-tight electrical implementation, for example, to connect multiple sensors. Likewise, the number of layers is not limited to two or three. For example, the use of a multilayer ceramic as a separating element is particularly advantageous 10 , which can be constructed, for example, up to 80 individual layers. These are each provided with via holes, in which metal is introduced. The layers 11 . 12 . 13 are firmly connected or baked together and form a monolithic part.

The ceramic layers 11 . 12 . 13 of the separating element 10 have a thickness of about 80μm. Due to the mutual offset of the filled holes, the pressure is not on the holes or metal fillings, but it is distributed over a large area over the individual layers.

With four cable elements or cable bushings 20 is the size of the electrical feedthrough in the lateral direction in the embodiment shown here only about 2mm. Despite this small size, the component withstands high pressures that can reach up to 1,500 bar.

to Production of pressure-tight electrical feedthrough become thin films made of a ceramic material with through-holes or via-holes, in the following metallic material is introduced. The holes are punched out and subsequently filled with a metal paste. This will be the position of the holes chosen so that at later Assemble the layers one lateral offset between each the vias thus created is present. Well be on the layer surfaces Conductor tracks formed, for example by vapor deposition of metal or by printing or screen printing of metal pastes. The positions and directions of the tracks are chosen so that they after joining the individual layers the mutually offset vias connect together to form one or more conduit elements, which extend through the entire layer structure. Subsequently, the Layers or ceramic layers stacked together and firmly together connected. By sintering the ceramic layers become one with each other baked, so that a monolithic structure results.

For a particularly rapid and cost-effective production, this is carried out in a batch process, wherein a ceramic tile or layer with a size of about 25 cm ^{2 is processed} as described above and then separated into a plurality of layers. Thereafter, the individual layers are stacked on each other so that the electrical feedthrough according to the present invention results in one or more continuous line elements extending from one side of the feedthrough to the other side.

A particularly cost-effective Production results from the use of green tape technology, at the ceramic layers before sintering elastic properties have.

The electrical implementation is inexpensive can be produced and has a high compressive strength at very low Size or high miniaturization. It is suitable for high temperatures and allows for easy Direct connection with electronic units or sensor chips. In the injection It connects an internal sensor electrically to the outside. As a result, the fuel flow in the Interior of the injector measured and fed back Sensor-actuator system for controlling the fuel flow allows. In operation, the measurement and control of the injector due to the measuring signal a particularly high accuracy of the injection quantity with each existing one injection and achieved with each injection.

Claims (11)

Injection nozzle for internal combustion engines, with a housing ( 81 ), one or more injection ports ( 83 ), an interior ( 84 ) for supplying fuel to the injection openings ( 83 ) and a measuring element ( 50 ) in the interior ( 84 ) is arranged to measure the fuel flow rate and / or another state parameter of the fuel, wherein the measuring element ( 50 ) by a pressure-tight electrical feedthrough ( 9 ) in the housing ( 81 ) of the injection nozzle ( 80 ) is connected to the outside space, characterized in that the electrical feedthrough ( 9 ) of several layers ( 11 . 12 . 13 ), each having one or more vias ( 21 . 22 . 23 ), wherein the plated-through holes ( 21 . 22 . 23 ) of two adjacent layers are arranged offset to one another and the electrical feedthrough ( 9 ) lateral tracks ( 31 . 32 ) which in each layer ( 11 . 12 . 13 ) located vias ( 21 . 22 . 23 ) to a continuous line element ( 20 ) connect. Injection nozzle according to claim 1, characterized in that the measuring element ( 50 ) is coupled to a control loop for controlling the injection quantity. Injection nozzle according to claim 1 or 2, characterized in that the lateral conductor tracks ( 31 . 32 ) between adjacent ones Layers ( 11 . 12 . 13 ). Injection nozzle according to one of claims 1 to 3, characterized in that the electrical feedthrough a separating element ( 10 ) of ceramic. Injection nozzle according to one of claims 1 to 4, characterized in that in the individual layers ( 11 . 12 . 13 ) are arranged one or more through holes, which are provided with an electrically conductive material. injection according to claim 5, characterized in that in the continuous Holes one Metal paste is introduced. Injection nozzle according to one of claims 2 to 6, characterized in that the electrical feedthrough ( 9 ) made of ceramic in green tape technology. Injection nozzle according to one of claims 2 to 7, characterized in that the electrical feedthrough ( 9 ) individual layers ( 11 . 12 . 13 ) having a thickness of 10 to 200 .mu.m, preferably 60 to 100 .mu.m, in particular 80 .mu.m. Injection nozzle according to one of the preceding claims, characterized in that the measuring element ( 50 ) is a pressure sensor. injection according to claim 9, characterized in that two or more pressure sensors are provided are to measure a differential pressure. Injection nozzle according to one of the preceding claims, characterized in that the measuring element ( 50 ) is arranged as a strain gauge and / or integrated in the injection nozzle.