WO2007012519A1 - Glowplug component for internal combustion engines with a ceramic filter element - Google Patents

Abstract

The invention relates to a method for production of a heating body (26; 88, 90) made from a ceramic composite material (64, 66, 72) for an engine component (12) of a self-ignition internal combustion engine. The following method steps are carried out in production of the heating body (26; 88, 90): a measuring channel (58) is generated during the forming process for the heating body (26; 88, 90), a porous, however, chemically identical material (66, 72) is introduced into the generated measuring channel (58), the heating body (26; 88, 90) with the introduced insulation material (72) is subjected to a thermal treatment, an integrated particle filter (74) is generated at the combustion chamber end (52, 54) of the heating body (26; 88, 90) the porosity of which is in the range of 1 vol. % and 90 vol. % and the mean pore diameter of which is in the range of 0.1 to 1000 ?m.

Description

Annealing component for internal combustion engines with ceramic filter element

The invention relates to an ignition component for an internal combustion engine with a ceramic filter element according to the preamble of claim 1.

State of the art

In today's internal combustion engines, be it self-igniting or spark-ignited internal combustion engines, the pressure prevailing in the combustion chamber of an internal combustion engine is a very important parameter for engine control and optimization of combustion. For this reason, pressure sensors are incorporated into glow components, such as glow plugs, for example, in self-igniting internal combustion engines , The glow components, such as the mentioned glow plugs, can be accommodated in the ideal case in an additional hole in the housing or in the glow plug itself to allow the measurement of the combustion chamber pressure of the internal combustion engine. When creating a measurement channel, there are three important problems:

First, there is a small amount of space on the glow component, such as a glow plug for integrating the hole available, also tends the measuring channel due to its smaller diameter to coking, and finally occur in such measurement channels pipe vibrations.

To remedy the problem of lack of space, the measuring channel could be drilled through the ceramic pin. However, this is only possible if the heating element used is a ceramic pin with an externally arranged heating element.

EP 0 412 428 B1 discloses a ceramic composite body containing a matrix which contains inclusions of hard material particles and / or other reinforcing components. A mixture of an organosilicon polymer with a metallic filler, which reacts with the decomposition products formed during the pyrolysis of the polymer compounds, is subjected to a pyrolysis and reaction process. The matrix is a mono- or multiphase, amorphous, semicrystalline or crystalline matrix of silicon carbide (SiC), silicon nitrite (Si ₃ N ₄ ), silicon dioxide (SiO ₂ ) or of mixtures thereof and B ₂ O ₃ (boron oxide) and BN (boron nitride) and B ₄ C (boron carbide) with C (carbon) or borosilicate glass (SiO ₂ / B ₂ O ₃ ), or for example from oxycarbides, oxynitrides, carbonitrides and / or oxycarbonitrides. The inclusions are hard material particles and / or other reinforcing components, carbides and / or nitrides of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and / or tungsten.

Such a material can be used for the production of a ceramic heater and offers the possibility to integrate the measuring channel in the ceramic heater itself.

However, in order to solve the third technical problem - as mentioned above - the coking problem of the measuring channel, it should be ensured that no soot particles get into the cold area of the measuring channel. This problem has not yet been solved satisfactorily.

Advantages of the invention

Object of the present invention is to prevent the coking of a measuring channel within a radiator of ceramic material.

According to the invention it is proposed to integrate at the tip of a measuring channel of a ceramic heater, a particle filter, which is made of a porous, but in terms of its chemical composition approximately identical material to the material of the radiator to the coking of the cold area of the radiator and thus the shutter to avoid a measuring channel passing through the radiator. The inventively proposed solution further counteracts the coking of the porous formed tip of the radiator due to the constant annealing and the related combustion of the carbon. The radiator of a glow plug for a self-igniting internal combustion engine is made of a ceramic composite material of precursor ceramic. Starting material is a polysiloxane, a polymer of Si, C, O and H, which is mixed with various fillers. First, a radiator is made of an insulating material on which subsequently a tip can be molded from a conductive material. The insulation material, possibly with a tip molded of conductive material, is overmolded with another material of conductive material (shaft material). This output body is drilled centrically, so that a measuring channel is obtained. The measuring channel is filled with a porous material, which is the mentioned insulating material or the conductive material from which the Lace is made, can act. Thereafter, the measuring channel is drilled and ground round the obtained starting body. The heat treatment (pyrolysis) of the starting body is followed by these production steps.

By selecting the fillers used, the electrical and physical property profile of the resulting after the pyrolysis ceramic composite of the radiator of the glow plug is tailored exactly to the requirements profile. The use of an oxygen-containing polysiloxane precursor as starting material allows easy workability under air and thus a simple production of low-cost products. The product contained after passing through the pyrolysis, i. The ceramic composite material has good strength and high chemical stability in terms of oxidation and corrosion.

Through the use of condensation-curing resins and foam stabilizers, the porosity of a ceramic can be adjusted within wide ranges. Thus, the porosity of the ceramic can be adjusted in the range between 1% by volume and 90% by volume, with an average pore diameter in the range between 0.1 to 1000 μm can be achieved. In addition, a bimodal porosity distribution can be achieved by the additional use of different porosity generating agents. For example, since the size of the soot particles is difficult to predict, a bimodal porosity distribution in the ceramic can produce two pore diameters, for example 0.1 μm and 10 μm, so that a significant portion of the soot particles are retained in the ceramic due to the bimodal porosity distribution can.

The glow plug according to the invention comprises a hollow ceramic heating element with a heatable particulate filter integrated therein, wherein the measuring channel in which the bakeable particle filter is accommodated, during the molding process of the green body, i. of the ceramic raw material. Advantageously, the material of the bakeable particle filter and the material of the ceramic heater differ only slightly from each other. The coking of the measuring channel is avoided due to the arranged in this at the combustion chamber end end bakeable particle filter.

By integrating a bakeable particulate filter on the combustion chamber facing side of the glow plug, ie at the combustion chamber end of the radiator of the glow plug, a pressure sensor is obtained, with all the benefits of a ceramic glow plug with respect to engine life, t _1O oo <2 s, which designates the period is that requires a glow plug, until at the combustion chamber facing tip a temperature of 1000 ° C prevails. The glow plug has an outer diameter of <4 mm, so that the cylinder head of an internal combustion engine extremely cramped space conditions to a necessary extent can be accommodated.

drawing

With reference to the drawing, the invention will be described below in more detail.

It shows:

FIG. 1 shows a combustion chamber pressure sensor system with a glow plug which comprises a radiator disposed on the combustion chamber side end of the glow plug, and

Figure 2 shows an embodiment of the radiator with extending in this measuring channel and an integrated at the combustion chamber end of the radiator end in the radiator bakeable particulate filter.

embodiments

The illustration according to FIG. 1 shows a combustion chamber pressure sensor system with a glow plug. A combustion chamber pressure sensor system 10 includes a glow plug 12 in which a force sensing element 14 is received. On both sides of the force measuring element 14, which can be formed annular, are within the glow plug 12 e- benfalls annular formable heating elements 16, which are connected via connecting lines 48 with a power electronics 20 in connection, via which the heating of the heating elements 16 is controlled. In addition to the supply electronics 20, an evaluation electronics 18 is received outside of the glow plug 12, which further processes the determined combustion chamber pressure signals of the force measuring element 14.

The glow plug 12 comprises a housing 22, in whose interior 24 a Drahtglühstromzuleitung 46 for a surrounded by the glow plug 12 radiator 26 extends. Further, in the housing 22 of the glow plug 12, a sealing cone 28 included, which serves to seal the interior 24 of the glow plug 12 against the radiator 26, so that prevents combustion chamber gases in the interior 24 of the housing 22 of the glow plug 12 arrive.

In the embodiment variant of the glow plug 12 shown in FIG. 1, this has a conical tip 30 at its end facing the combustion chamber of an internal combustion engine, which is exposed to the combustion chamber gases. The glow plug 12 according to the embodiment shown in Figure 1 is symmetrical to its axis 34 constructed. The signal detected by the force measuring element 14 is transmitted via signal lines 36 from the force measuring element 14 to the evaluation electronics 18. In the interior 24 of the glow plug 12 is also a sleeve-shaped force transmission element 38, which rests on the end face of the sealing cone 28 enclosed by the radiator 26. At the other end of the sleeve-shaped force transmission element 38 is one of the heating elements 16 at. Between the other of the heating elements 16 and a biasing member 40 is also a sleeve-shaped member 42, which encloses the extending in the interior 24 of the glow plug 12 lines 46 and 48 and 36 respectively.

The glow plug 12 illustrated in FIG. 1 comprises a heating body 26, which is manufactured from a ceramic composite material made from precursor ceramic. The starting material of this ceramic composite material is a polysiloxane, i. a polymer of Si, C, O and H, which is mixed with various fillers. By selecting the fillers, the electrical and physical property profile of the resulting after the pyrolysis ceramic composite material of the glow plug 12 is tailored exactly to their requirements profile. The use of an oxygen-containing polysiloxane precursor material as the starting material allows for easy processability under atmospheric conditions and thus the production of inexpensive radiators 26 made of a ceramic material. The product resulting from the pyrolysis, i. the present after the pyrolysis composition of the starting material ceramic composite material with the filler mixed therewith, has a good strength and high chemical stability in terms of oxidation and corrosion and is also harmless to health.

The illustration according to FIG. 2 shows, on an enlarged scale, a ceramic heating element of a glow plug according to the illustration in FIG.

The radiator 26 shown in Figure 2 includes a first end face 50 and a in the illustration of Figure 2 as a flat surface 54 formed second end face 52. The second end face 52 of the radiator 26 made of ceramic composite material combustion chamber gases 86 is exposed. The pressure in the combustion chamber acts on the force measuring element 14 via a measuring channel 58.

The radiator 26 has a lateral surface 56. Further, the radiator 26 is constructed in two parts as shown in Figure 2 and includes a first radiator part 88 and a second radiator part 90, which rest along a butt joint 68 to each other. Both the first radiator part 88 and the second radiator part 90 are of the measuring element passage 58, which is obtained, for example, by drilling a green body, ie the composite ceramic material in the untreated state. The illustration according to FIG. 2 also shows that the measuring channel 58 has an inner diameter 60. The measuring channel 58 has an undersize with regard to its diameter 60 in relation to an outer diameter 80 of a bakeable particulate filter 74. This undersize generated in the second radiator part 90, an annular surface 78 against which the bakeable particulate filter 74. The axial extension of the bakeable particulate filter 74 is indicated by reference numeral 82, its outer diameter designated by reference numeral 80. The bakeable particle filter 74 terminates flush with the second end face 52 of the radiator 26 and is acted upon by the combustion chamber gases indicated by reference numeral 86. The heater 26 of the first conductive material 64 has an outer diameter 70; The same applies to the second radiator part 90, which is made of the second conductive material 66 and also has an outer diameter 70.

From the illustration according to FIG. 2, it is also apparent that the interior of the measuring channel 58 is filled with an insulating material 72 in the heating element 26 constructed in this embodiment from a plurality of materials. First, a body is made of an insulating material 72, on which a tip of the second conductive material 66 can be molded. The obtained composite of the insulating material 72 with optionally molded second conductive material tip 66 is then overmolded with the first conductive material 64 (shaft material). Subsequently, the resulting body obtained from the first conductive material 64 (shaft material), the second conductive material 66 (tip) and the standard insulating material 72 is bored centrally, so that the measuring channel 58 is formed. In these, either the standard insulating material 72 or depending on the desired annealing properties, the second conductive material 66 can be lulled in powder form. This is followed by a re-drilling of the measuring channel 58 and a round grinding of the green body obtained, made of the first conductive material 64 (shaft material), the second conductive material 66 (tip) and the standard insulation material 72. The measuring channel 58 serves to transmit the pressure prevailing in the combustion chamber of the internal combustion engine the force measuring element 14, which may be embodied for example as a membrane.

For the production of the embodiment shown in Figure 2 in two parts radiator 26 made of a ceramic composite material, a bore is introduced into the green body of the ceramic composite material, which defines the diameter 60 of the measuring channel 58. In a subsequent process step, either the standard insulating material 72 in powder form or the second conductive material 66 is filled into the measuring channel 58. According to the material selected for filling the measuring channel 58, be it the standard insulating material 72 or the second conductive material 66, the annealing properties of the heater 26 thus obtained can be adjusted. Via pressureless crosslinking in a temperature range between 150 ° C. to 200 ° C., the required porosity is set by evaporating the condensation products such as, for example, ethanol or water from the standard insulating material 72 or the second conductive material 66. By designated in Figure 2 by reference numeral 76 L-shaped approach the two layers of the first conductive material 64 are separated from each other.

The adjustment of the porosity can be carried out in a range between 1% by volume and 90% by volume. An enlargement of a receiving bore for receiving the bakeable particle filter 74 on the outer diameter 80, is achieved by re-drilling the ceramic composite material. Thereafter, the radiator 26 is installed in a glow plug 12. The heating element 26 can be pressed, for example, into the plug housing in the form of a pre-compact. In the tubular housing of the glow plug 12 next to other components such as, for example, at the combustion chamber remote end of a ceramic sleeve and a metal ring can be embedded. After these individual elements have been embedded in the tubular housing of the glow plug 12, the glow plug is pressed into the combustion chamber end of the plug housing by means of force and a sealing material is compressed. Subsequently, the housing 22 of the glow plug 12 can be closed by means of a sealing ring or the like. In a central opening of the housing 22 of the connecting bolt can be performed for electrical contacting. After a final setting of a defined pressing force, the sealing ring can be fixed by a material, non-positive or positive connection, such as caulking, welding, compression, screwing, soldering or gluing.

In addition to the introduction of a foamable standard insulation material 72 in the previously introduced into the green body of ceramic composite material bore of the measuring channel 58 and an insert can be inserted in the thus pre-machined green body. In a further production step, then the material of the bakeable particulate filter 74 and the standard insulation material 72 can be injected at very low pressure, which can be done for example by means of the foam injection method. In accordance with the composition of the injected material forming the bakeable particle filter 74, the desired porosity is set in a range between 1% by volume and 90% by volume, with an average pore diameter at the bakeable particle filter 74 being between 0.1 μm and 1000 μm can be adjusted. An additional bimodal porosity distribution can be achieved by using different porosity generating agents. The bakeable particle filter 74 is made in the same manner as the entire ceramic pin. The material from which the bakeable particle filter 74 is made differs only in terms of its porosity from the second conductive material 66, from which the second radiator part 90 which can be removed from FIG. 2 is manufactured.

With regard to the porosity, which finally sets on the bakeable particulate filter 74, the porosity of the bakeable particulate filter 74 can be adjusted by the use of condensation-crosslinking resins and by the use of suitable foam stabilizers. In an advantageous manner, the first conductive material 64, from which the first radiator part 88 is made, and the second conductive material 66, from which the second radiator part (tip) and the heatable particle filter 74 are made, are selected approximately chemically identical, in particular at the tip of the measuring channel 58, which is exposed to the combustion chamber gases 86, the coking of the cold region and thus the closure of the measuring channel 58 in the heater 26 made in FIG. 2 from the first conductive material 64 and the second conductive material 66 can be prevented in an effective manner.

In addition, can be avoided by the present invention proposed integration of the bakeable particulate filter 74 at the combustion chamber end of the radiator 26 coking at the combustion chamber facing end of the radiator 26 due to the constant annealing and the concomitant continuous combustion of carbon. Due to the prevailing at the combustion chamber end of the glow plug 12 temperature levels of about 1000 ° C to 1150 ° C burn the soot particles during annealing of the pin during operation. Should soot particles have attached to the glow plug 12, they burn, since the glow plug 12 reaches a temperature of 1000 ° C within the time t ₁₀ oo <2 s at the start of the internal combustion engine so that soot particles are not in the formed in the radiator 26 measuring channel 58 wandering into it.

The porosity at the combustion chamber end of the heating element 26, which is acted upon by the combustion chamber gases 86, can be achieved by the use of already strongly precrosslinked or partially pyrolyzed material. The bakeable particulate filter 74, from the starting material of which condensation products such as ethanol and water are expelled, which sets the presettable porosity, can also be produced from precrosslinked or partially pyrophysylated material. In this case, the porosity of the bakeable particle filter 74 is not established by a condensation reaction, but by the lower packing density of teilpyrolysiertem powder. Also according to this embodiment it is ensured that no soot particles get into the cold region of the measuring channel 58 and enforce this over the service life of the glow plug 12. By cold range is meant the area of the radiator 26 made of ceramic composite material, which is the first face page 50 of the according to the embodiment in Figure 2 made of several materials radiator 26 is closer, that is remote from the acted upon by the combustion chamber gases 86 second end face 52 of the radiator 26. The greater the chemical similarity between the second conductive material 66 and the material from which the bakeable particulate filter 74 is made with respect to the first conductive material 64 from which the first heater body 88 is made, the better the cold region of the sensing channel 58, which extends substantially through the first radiator part 88, protected against coking by accumulating soot particles. The filled with standard insulation material 72 measuring channel 58 extends into the second radiator part 90 (tip), which may be made of the second conductive material 66. The measuring channel 58 has the task of pressure transmission of the combustion chamber pressure on the force measuring unit 14, which may be formed as a membrane in addition to other possible embodiments. Accordingly, the integrated bakeable particulate filter 74 of the heating element 26 can be manufactured both from the standard insulating material 72 filled with powder in the measuring channel 58 and from the second conductive material 66 filled with powder in the measuring channel 58, depending on the required application profile of the glow plug 12.

Bezueszeichenliste

Combustion chamber pressure sensor system by 26

Glow plug 72 Insulation material

Force measuring element 74 bakeable particle filter

Heating elements 76 L-shape insulation material

Evaluation electronics 78 Ring surface

Supply electronics 80 Outer diameter ausheizba

Housing particulate filter 74

Interior 82 Filter thickness

Radiator 84 support surface

Sealing cone 86 combustion chamber gases conical tip 88 first radiator part

Force 90 second radiator part (Spit

Axis ze)

Signal lines Force measuring element

Power transmission element

biasing member

shell

external thread

Drahtglühstromzuleitung

Connecting cables heating element

first end face ceramic

Radiator second face ceramic

radiator

plane surface

lateral surface

measuring channel

Diameter measuring channel

Undersize first conductive material second conductive material (tip)

Stoßiuge

Outer diameter radiator

Claims

claims 1. A method for producing a radiator (26) made of a ceramic composite material (64, 66, 72) for an engine attachment component (12) of an internal combustion engine with the following method steps: a) in the heating body (26, 88, 90) made of ceramic composite material (64, 66, 72), a measuring channel (58) is produced during its shaping process, b) the measuring channel (48) is filled with a porous, but chemically substantially identical material (66, 72), c) the heating body (26, 88, 90) is subjected to a heat treatment with the filled-in porous material (66, 72), d) wherein at the combustion chamber end (52, 54) of the radiator (26; 88, 90) a heatable integrated particulate filter (74) is produced whose porosity in the range between 1 vol .-% and 90 vol .-% and its average pore diameter in the range of 0.1 to 1000 microns. 2. The method according to claim 1, characterized in that the porous material (66, 72) is filled with condensation-curing resins or foam stabilizers or teilpyroly- siertem material in the measuring channel (58). 3. The method according to claim 2, characterized in that the porous material (66, 72) in powder form or by means of foam spraying into the measuring channel (58) of the radiator (26, 88, 90) is introduced. 4. The method according to claim 1, characterized in that in process step c) the heat treatment in a temperature range between 150 ° C and 200 ° C and the porous material (66, 72) cross-linked without pressure, wherein condensation products are evaporated. 5. The method according to claim 1, characterized in that the heating body (26; 88, 90) after carrying out the method steps a) to d) at the combustion chamber end (52, 54) for adjusting the thickness (82) of the bakeable particulate filter (74) is machined. 6. The method according to claim 1, characterized in that the porosity of the bakeable particulate filter (74) at the combustion chamber end (52, 54) of the heater (26; 88, 90) by a condensation reaction in the porous material (66, 72) is adjusted. 7. The method according to claim 1, characterized in that the porosity of the bakeable particulate filter (74) through the porous material (66, 72) is set in teilpyrolysierter powder form with low packing density. 8. The method according to claim 1, characterized in that the measuring channel (58) in the radiator (26; 88, 90) is generated by use of an insert. 9. The method according to claim 1, characterized in that the conductivity of a second conductive material (66) at the combustion chamber end in the region of the tip (90) of the radiator (26) is lower compared to the conductivity of the radiator (26, 88, 90) and the integrated, bakeable particulate filter (74) is made from the second conductive material (66). 10. engine mounting component, in particular a glow plug (12) with a radiator (26; 88, 90) for an internal combustion engine, produced according to one or more of the method claims 1 to 9, characterized in that the bakeable particulate filter (74) at the combustion chamber end (52 , 54) of a measuring channel (58) of the radiator (26; 88, 90) is integrated in this. 11. engine mounting component according to claim 10, characterized in that the measuring channel (58) passes through the radiator (26; 88, 90) axially and the measuring channel (58) has a diameter (60) which is smaller than the diameter (80) of integrated, bakeable particulate filter (74). 12. Motoranbaukomponente according to claim 11, daduruch characterized in that the bakeable particulate filter (74) on an annular surface (78, 84) of the measuring channel (58) is applied and a mean pore diameter between 0.1 and 1000 microns and a porosity in the range between 1 vol .-% and 90 vol .-%.