DE19945673A1 - Injection nozzle for internal combustion engines - Google Patents

Abstract

An injector nozzle (80) for internal combustion engines, having a sensor (50) in the inner or outer area thereof in order to measure the flow of fuel through said injection nozzle or another status parameter of the fuel. The sensor (50) is connected to the outer area via a pressure-tight electric leadthrough (9) disposed in the housing (81) of the injector nozzle (80). The exact amount of fuel injected individually into the combustion chamber is controlled by a feedback sensor/actuator system.

Description

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

When burning a fuel-air mixture, it is particularly important that one fine distribution of the fuel, for example gasoline, diesel or kerosene, with the necessary combustion air is reached. This is achieved through injectors that the fuel is distributed finely and in the necessary quantity to the combustion chamber of an engine respectively. Such an injector is in an article from Zexel Corporation in the AMAA Conference volume (ISBN 3-540-64091-6) p. 233.

In the known injection nozzles or injection devices, the one to be injected The amount of fuel for each injection is based on the most accurate prior calibration possible Injector or injector set. So it is already in the manufacture of the Injection nozzle specifies the amount of fuel during an injection pulse or Injection process gets into the combustion chamber. Resulting from manufacturing tolerances however, there are fluctuations in the injection quantity during an injection between the manufactured injectors.

To avoid particularly large deviations from the normal value, a Separation of the relevant injection nozzles during manufacture, which leads to high costs arise. In addition, the calibration is relatively complex. In addition, none there is an individual characteristic curve for each injector after production. Therefore the amount of injection varies in operation from injector to injector, as well as from one Injection process to the next. The accuracy of the injection quantity is therefore limited.

When the engine is running, the limited accuracy of the injection quantity results in that there is an increased risk of poor mixture formation, d. that is Mixing ratio between fuel and air is unfavorable. One consequence of this is that part of the fuel leaves the combustion chamber unburned and harmful exhaust gases  generated. Furthermore, an unfavorable mixing ratio results in a worse one Efficiency of the internal combustion engine.

It is therefore the object of the present invention to provide an injection nozzle for a To create internal combustion engine with which the injection quantity with increased Accuracy can be determined.

This object is achieved by the injection nozzle according to claim 1. Further advantageous features, aspects and details of the invention result from the dependent claims, the description and the drawings.

The injection nozzle according to the invention for internal combustion engines comprises a Housing, which has one or more injection openings, and an interior for Supply of fuel to the injection openings, the inside or outside of the Injection nozzle is arranged to measure the fuel flow and / or a to measure other state parameters of the fuel. This allows everyone Injector individually the actual injection quantity during the respective injection be determined. By measuring further state parameters of the fuel, such as For example, pressure or temperature, the combustion process can continue be optimized.

Preferably, the measuring element is in the interior and by a pressure-tight electrical Carried out in the housing of the injection nozzle connected to the outside.

The measuring element is preferably connected to a control circuit for controlling the injection quantity coupled. This results in a feedback sensor-actuator system, resulting in a direct, immediate optimization of the amount of fuel injected according to current requirements can take place.

The electrical feedthrough is advantageously constructed from a plurality of layers each have one or more vias, the Vias of two adjacent layers z. B. staggered are. This creates a particularly high compressive strength in the electrical field  Implementation accomplished. The pressure sensor or the measuring element can also be simple be separated from the interior or exterior by a membrane.

The electrical implementation can, for. B. include lateral traces, which in the vias located in individual layers to a continuous Connect the line element. The lateral conductor tracks preferably run between contiguous layers. As a result, the pressure is not on the individual Plated-through holes, but is distributed over the layer surfaces.

The electrical feedthrough advantageously comprises a ceramic separating element, the Z. B. is layered or multi-layered. In the individual layers can one or more through holes may be arranged with an electrical conductive material are provided. For example, one in the through holes Be introduced metal paste. This results in a simple and inexpensive Manufacturing, e.g. B. by means of batch processing, but still a high Degree of miniaturization of the electrical implementation is achieved with high strength.

The electrical feedthrough is preferably made of ceramic using green tape technology manufactured. The individual layers have e.g. B. a thickness of 10 to 200 microns, preferably 60 to 100 microns, and especially about 80 microns. These measures make one special rational, cost-effective production with a very small design and still high Strength reached.

The measuring element can, for. B. be a pressure sensor with a membrane and / or as Strain gauges are available.

According to a further aspect of the invention, an injection nozzle is created which has a Includes sensors for determining the amount of fuel from the injector is emitted, the sensor system being miniaturized and integrated into the nozzle. By Quantity determination directly at the outlet increases the quantity stability of the injector Injector and achieved from injection to injection, in particular also one feedback control is possible.  

The present invention is described below with reference to the drawings, in which: to them

FIG. 1 shows an injection nozzle according shows a preferred embodiment of the invention;

FIG. 2 shows a longitudinal section through the front region of the injection nozzle according to the invention shown in FIG. 1;

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

Fig. 4 shows the measuring element and the electrical implementation schematically as a sectional view;

Fig. 5 shows a schematic sectional view through the electrical feed-through in the housing of the injector.

Fig. 1 shows an injection nozzle 80 for an internal combustion engine having a pressure-tight electrical lead-through 9. The electrical feedthrough 9 extends through a region of the housing 81 of the injection nozzle 80 into its interior. A sensor is attached there with which the fuel flow within the injection nozzle 80 is measured. The sensor located in the interior of the injection nozzle 80 is supplied with current via lines 82 located outside. During operation, the measurement signals obtained are fed via lines 82 to a control circuit which controls the injection quantity of the fuel or the opening of the injection valve. In the interior of the injector 80 , through which the fuel flows, z. B. a pressure of about 1500 bar that the electrical feedthrough withstands.

Of course, other types of sensors in the interior of the injector 80 are also possible, which can measure various parameters, such as. B. the pressure or temperature of the fuel. The respective sensor is electrically connected to the outside for the transmission of the measurement signals and / or for the power supply via the electrical feedthrough according to the invention.

Fig. 2 shows a longitudinal section through the front region of the injection nozzle 80 with the electrical lead-through 9. The cylindrical housing 81 of the injection nozzle 80 has a plurality of nozzle openings 82 at its front end. Inside the housing 81 there is a movable valve needle 90 , which opens the nozzle openings 82 for injecting fuel into the combustion chamber of the engine. For this purpose, the valve needle 90 is moved upward in the direction of arrow B with each injection, so that the needle tip lifts off the needle seat and fuel is pushed out of the interior 84 through the nozzle openings 82 . The fuel is located in the interior 84 between the housing wall 81 and the valve needle 90 of the injection nozzle 80 .

The pressure-tight electrical feedthrough 9 is located in a region of the housing wall 81 and forms a pressure-tight closure, so that under the high pressure in the interior 84 of the injection nozzle 80, no fuel can flow outward through the electrical feedthrough. In the interior 84 of the injection nozzle 80 , a measuring element 50 is arranged as a sensor, which serves to measure the fuel flow through the injection nozzle 80 .

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

In Fig. 3, the pressure-tight electrical bushing with the connected sensor or measuring element 50 in an exploded view is shown. It comprises a plurality of ceramic layers 11 , 12 , 13 which are firmly baked or bonded to one another. The layers 11 , 12 , 13 are located in a cylindrical cavity 61 , which is formed in a housing or frame 60 , which is also cylindrical. On the underside of the ceramic layer 11 facing the viewer, two conductor tracks 31 are applied, which extend laterally along the layer boundary. Each conductor track 31 connects a line section 22 , which extends through the middle layer 12 , to a line section 21 arranged offset thereto, which extends through the first layer 11 (see FIG. 4).

As can be seen in FIG. 4, the line sections 22 are each connected to a further conductor track 32 , which is located on the adjacent layer 13 . The course of the two line elements 20 with their associated line sections 21 , 22 , 23 and lateral line sections or conductor tracks 31 , 32 is shown in FIG. 4. There is a lateral offset between the line sections 21 and 22 and 22 and 23 of each line element 20 , which is bridged by the respective conductor track 31 , 32 .

The layers ( 11 , 12 , 13 ) of ceramic which are firmly connected to one another form a separating element 10 . The measuring element 50 , which is formed by a conductor track or a wire or metal wire, which is arranged on the separating element 10 , is located on the outside of the separating element 10 or the outer layer 13 . With the measuring element 50 , a flow measurement can be carried out in a flowing medium by measuring the electrical resistance of the conductor track. As is known, this resistance is temperature-dependent and thus changes as a function of the flow or flow velocity of the flowing medium. The fuel flow is measured via the heating power and the ohmic resistance.

The structure of the electrical feedthrough 9 of the injection nozzle 80 is described in more detail below with reference to FIG. 5. The electrical feedthrough shown in section shows the separating element 10 made of insulating material which is constructed or manufactured from the layers 11 , 12 , 13 . The layers 11 , 12 , 13 are ceramic layers which are aligned parallel to one another and are firmly connected to one another at the layer boundaries. In each layer there is a section 21 , 22 , 23 of a line element 20 , which represents an electrical connection between the top 10 a and the bottom 10 b of the separating element. The sections 21 , 22 , 23 of the line element 20 are arranged offset to one another and connected to one another by the lateral conductor tracks 31 , 32 . On the top 10 a and the bottom 10 b of the separating element 10 there is a contact pad or contact element 30 a, 30 b, which consists of a metallic layer and serves as a connection for electrical elements on both sides of the separating element 10 .

The line sections 21 , 22 , 23 are formed by metals or metallizations, which are formed in through holes in the ceramic layers 11 , 12 , 13 . 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 only on their edge or on their inner wall to form the electrically conductive connection between the top and bottom 10 a, 10 b of the separating element 10 .

The holes that form the line sections 21 , 22 , 23 with the metallization run 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. Each section 21 , 22 , 23 extends through a layer 11 , 12 , 13 , so that the offset occurs at the layer boundaries. Each section 21 , 22 , 23 forms a plated-through hole in the respective layer 11 , 12 , 13 .

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

The line elements 20 formed from the individual sections 21 , 22 , 23 or through-contacts and conductor tracks 31 , 32 run zigzag through the separating element 10 . In the section of the electrical bushing shown in FIG. 5, for the sake of simplicity, only two line elements 20 are shown, which run through three adjoining ceramic layers 11 , 12 , 13 . However, three, four or significantly more line elements 20 can also be provided in the pressure-tight electrical feedthrough, e.g. B. to connect several sensors. Likewise, the number of layers is not limited to two or three. Z is particularly advantageous. B. the use of a multilayer ceramic as a separating element 10 , which can be constructed, for example, from up to 80 individual layers. These are each provided with via holes in which metal is inserted. 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 approximately 80 μm. Due to the mutual offset of the filled holes, the pressure does not bear on the holes or metal fillings, but is distributed over a large area over the individual layers.

With four line elements or line bushings 20 , the size of the electrical bushing in the lateral direction in the embodiment shown here is only approximately 2 mm. Despite this small size, the component withstands high pressures, which can be up to 1,500 bar.

Thin films are made from to produce the pressure-tight electrical feedthrough a ceramic material with through holes or via holes into which then metallic material is introduced. The holes are punched out and then filled with a metal paste. The position of the holes is like this chosen that later when the layers are put together, a lateral offset is present between the vias thus created. Now be on the Layer surfaces of conductor tracks are formed, for example by vapor deposition of Metal or by printing or screen printing of metal pastes. The positions and Directions of the conductor tracks are chosen so that after the assembly of the individual layers the mutually offset vias with each other connect to form one or more line elements, which are characterized by the stretch the entire layer structure. Then the layers or Ceramic layers placed on top of each other and firmly connected. By sintering the ceramic layers are baked together so that a monolithic Structure results.

For particularly fast and inexpensive production, this is carried out in a batch process, a ceramic tile or layer having a size of approximately 25 cm ^{2 being processed} as described above and then being separated into a plurality of layers. The individual layers are then stacked on top of one another or firmly connected to one another, so that the electrical feedthrough according to the present invention results with one or more continuous line elements which extend from one side of the feedthrough to the other side.

A particularly cost-effective production results from the use of the green tape Technology in which the ceramic layers have elastic properties before sintering have.

The electrical feedthrough is inexpensive to manufacture and has a high Compressive strength with very small size or high miniaturizability. she is  suitable for high temperatures and enables a simple direct connection with Electronic units or sensor chips. It connects you inside the injector lying sensor electrically with the outside. As a result, the fuel flow in the Interior of the injection nozzle measured and a feedback sensor-actuator system for Control of fuel flow allows. In operation, the measurement and Control of the injection nozzle based on the measurement signal a particularly high accuracy the injection quantity for each existing injection nozzle and for each injection process achieved.

Claims (15)

1. Injection nozzle for internal combustion engines, with a housing ( 81 ) having one or more injection openings ( 82 ), and an interior ( 84 ) for supplying fuel to the injection openings ( 82 ), characterized by a measuring element ( 50 ) in the Interior ( 84 ) or exterior is arranged to measure the fuel flow and / or another state parameter of the fuel. 2. Injection nozzle according to claim 1, characterized in that the measuring element ( 50 ) is coupled to a control circuit for controlling the injection quantity. 3. Injection nozzle according to one of the preceding claims, characterized in that 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. 4. Injection nozzle according to claim 3, characterized in that the electrical feedthrough ( 9 ) is constructed from a plurality of layers ( 11 , 12 , 13 ), each having one or more vias ( 21 , 22 , 23 ), the vias ( 21 , 22 , 23 ) of two adjacent layers are arranged offset to one another. 5. Injection nozzle according to claim 3 or 4, characterized in that the electrical feedthrough ( 9 ) comprises lateral conductor tracks ( 31 , 32 ), which in the individual layers ( 11 , 12 , 13 ) located vias ( 21 , 22 , 23 ) connect a continuous line element ( 20 ). 6. Injection nozzle according to claim 5, characterized in that the lateral conductor tracks ( 31 , 32 ) run between adjacent layers ( 11 , 12 , 13 ). 7. Injection nozzle according to one of claims 3 to 6, characterized in that the electrical feedthrough comprises a separating element ( 10 ) made of ceramic. 8. Injection nozzle according to one of claims 4 to 7, characterized in that in the individual layers ( 11 , 12 , 13 ) one or more through holes are arranged which are provided with an electrically conductive material. 9. Injection nozzle according to claim 8, characterized in that in the through holes a metal paste is introduced. 10. Injection nozzle according to one of claims 2 to 9, characterized in that the electrical feedthrough ( 9 ) is made of ceramic in green tape technology. 11. Injection nozzle according to one of claims 2 to 10, characterized in that the electrical feedthrough ( 9 ) comprises individual layers ( 11 , 12 , 13 ) with a thickness of 10 to 200 µm, preferably 60 to 100 µm, in particular 80 µm. 12. Injection nozzle according to one of the preceding claims, characterized in that the measuring element ( 50 ) is a pressure sensor. 13. Injection nozzle according to claim 12, characterized in that two or more Pressure sensors are provided to measure a differential pressure. 14. Injection nozzle according to one of the preceding claims, characterized in that the measuring element ( 50 ) is arranged as a strain gauge and / or is integrated in the injection nozzle. 15. Injection nozzle for internal combustion engines, in particular according to one of the preceding claims, characterized by a sensor system for taxation the amount of fuel injected from the injector, the Sensor technology is miniaturized and integrated into the injection nozzle.