Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/40—Heating elements having the shape of rods or tubes
  • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23Q—IGNITION; EXTINGUISHING-DEVICES
  • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23Q—IGNITION; EXTINGUISHING-DEVICES
  • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
  • F23Q7/001—Glowing plugs for internal-combustion engines
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
  • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
  • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
  • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/027—Heaters specially adapted for glow plug igniters

Definitions

• the invention is based on a pin heater in a glow plug and on a glow plug according to the type of the independent claims.
• a pin heater in a glow plug for diesel engines which has at least one essentially inner insulation layer and at least one essentially outer guide layer, both layers comprising a ceramic composite structure.
• the outer conductive layer in the area of a tip of the pin heater on the combustion chamber has a U-shape in longitudinal section, so that the outer guide layer surrounds the insulation layer in the area of the tip of the pin heater on the combustion chamber.
• the pin heater according to the invention and the glow plug according to the invention with the features of the independent claims have the advantage that the pin heater comprises a second conductive layer, which also comprises a ceramic composite structure, that the second conductive layer is connected to the first conductive layer in the region of a tip of the pin heater on the combustion chamber side, and that the second conductive layer runs inside the insulation layer.
• a reference potential such as the Vehicle mass
• the second conductive layer is then already electrically insulated from the outside by the insulation layer, with the exception of the region of the tip of the pin heater on the combustion chamber side. This means that there is no need for an insulation layer that electrically isolates the pin heater from the outside, and thus the manufacturing outlay can be reduced.
• the first conductive layer is connected to a reference potential, in particular vehicle ground, and the second conductive layer is connected to an operating voltage potential, in particular the positive pole of a vehicle battery. In this way, there is no need for external electrical insulation of the pin heater as described.
• first conductive layer, the second conductive layer and the insulation layer are arranged essentially rotationally symmetrically in cross section. In this way, an isotropic shrinking of the insulation layer and the conductive layers can be achieved in the manufacture of the pin heater, in which gaseous substances are separated from the respective ceramic material by heating.
• the essentially rotationally symmetrical arrangement of the insulation layer and the two conductive layers also leads to better concentricity of the pin heater.
• the insulation layer has a preferred direction in cross-section in which it is stronger than at least one other direction. In this way, on the one hand, bending of the insulation layer during the manufacturing process of the pin heater, in particular when connecting the insulation layer to the first conductive layer, is largely prevented. This increases the mechanical robustness of the pen heater. In addition, the electrical resistance is increased in the preferred direction, so that less leakage currents flow between the first and the second conductive layer in this direction.
• the second conductive layer has a preferred direction in cross section, in which it is more extensive compared to at least one other direction. In this way, bending of the second conductive layer during manufacture of the pin heater and, in particular, during the connection of the second conductive layer to the insulation layer is largely excluded. This also increases the mechanical robustness of the pen heater.
• the first conductive layer in the region of the tip of the pin heater on the combustion chamber comprises a first ceramic material that the first conductive layer otherwise comprises a second ceramic material and that the first ceramic material has a higher electrical resistivity than the second ceramic material.
• a higher electrical resistance can be realized for the first conductive layer in the area of the tip of the pin heater on the combustion chamber than outside the area of the tip on the combustion chamber. The heating of the pin heater can thus be concentrated on the area of the tip of the pin heater on the combustion chamber side.
• FIG. 1 shows a longitudinal section through a pin heater of a glow plug according to a first embodiment
• FIG. 2 shows a cross section of this pin heater according to the first embodiment
• FIG. 3 shows a longitudinal section through a pin heater of a glow plug according to a second embodiment
• Figure 4 shows a cross section through this pin heater according to the second embodiment.
• 5 denotes a glow plug for installation in a cylinder head of an internal combustion engine, for example a diesel engine.
• the glow plug 5 comprises a pin heater 1.
• the pin heater 1 is shown in a longitudinal section, the pin heater 1 comprises an essentially inner insulation layer 10, which is encased on the one hand by an essentially outer first conductive layer 15, 16 and which on the other hand encases a second conductive layer 20.
• the second conductive layer 20 thus runs inside the insulation layer 10.
• the first conductive layer 15, 16 is tubular and, according to FIG. 2, has an essentially annular cross section.
• the insulation layer 10 encased by the first conductive layer 15, 16 is also tubular and, according to FIG. 2, has an essentially annular cross section.
• the second conductive layer 20 is electrically conductively connected to the first conductive layer 15, 16, the first conductive layer 15, 16 in the region of the tip on the combustion chamber side 40 of the pin heater 1 encloses the insulation layer 10 and the second conductive layer 20 in a longitudinal section according to FIG. 1 approximately U-shaped.
• the first conductive layer 15, 16, the second conductive layer 20 and the insulation layer 10 are each formed from a ceramic composite structure. That for the insulation layer 10
• the ceramic composite structure used has a considerably higher specific electrical resistance than the ceramic composite structure used for the guide layers 15, 16, 20. In this way, leakage currents between the first conductive layer 15, 16 and the second conductive layer 20, with the exception of the region of the tip 40 of the pin heater 1 on the combustion chamber side, in which the first conductive layer 15, 16 is connected to the second conductive layer 20, are significantly suppressed.
• the first conductive layer 15, 16 can now be connected to an operating voltage potential 30, for example a positive pole of the vehicle battery, and the second conductive layer 20 can be connected to a reference potential 25, for example the vehicle ground.
• the first conductive layer 15, 16 represents the supply line and the second conductive layer 20 represents the discharge for the heating current.
• the second conductive layer 20 with the operating voltage potential 30 and the first conductive layer 15, 16 with the Reference potential 25 connected.
• the second conductive layer 20 is the supply line and the first conductive layer 15, 16 is the discharge line for the heating current.
• the second conductive layer 20 is already insulated from the outside as a feed line by the insulation layer 10.
• the diameter of the pin heater 1 can be, for example, 3.3 mm.
• the first conductive layer 15, 16 in the area of the tip 40 of the pin heater on the combustion chamber side 1 comprises a first ceramic material 16, whereas the first conductive layer 15, 16 otherwise comprises a second ceramic material 15.
• the first ceramic material 16 has a higher specific electrical resistance than the second ceramic material 15 and the second conductive layer 20 at the temperatures occurring during operation of the pin heater 1.
• the first ceramic material 16 encloses the insulation layer 10 and the second conductive layer 20 in a U-shape in longitudinal section according to FIG.
• the resulting increased electrical resistance in the area of the combustion chamber-side tip 40 of the pin heater 1 concentrates the heating of the pin heater 1 in the area of the combustion chamber-side tip 40 of the pin heater 1 and thus displaces it as far as possible into the combustion chamber of the internal combustion engine. This enables a short heating-up time from -20 ° C to a temperature of 1000 ° C in the order of 2s and a steady temperature of over 1200 ° C.
• the pin heater 1 is heated, gaseous substances from the first conductive layer 15, 16, from the insulation layer 10 and can be separated from the second conductive layer 20. This causes these layers to shrink.
• Such shrinkage also occurs when the pin heater 1 is sintered Process, a hot pressing process, a hot isostatic pressing process or a similar method is produced.
• the insulation layer 10 shrinks due to its different composition from the first conductive layer 15, 16 and the second conductive layer 20, each different from these two conductive layers. Due to the rotationally symmetrical arrangement of all layers 10, 15, 16, 20, all layers 10, 15, 16, 20 shrink isotropically, so that there are lower mechanical stresses due to differences in shrinkage.
• the pin heater 1 When the pin heater 1 is operated in the cylinder head, the pin heater 1 is cyclically heated and cooled. Due to the different material for the insulation layer 10 compared to the first conductive layer 15, 16 and the second conductive layer 20, there is a different thermal expansion of the insulating layer 10 in comparison to the first conductive layer 15, 16 and to the second conductive layer 20. The thermally induced mechanical stresses which are formed in the process are considerably reduced on account of the rotational symmetry.
• Another advantage of the essentially concentric and rotationally symmetrical arrangement of the layers 10, 15, 16, 20 of the pin heater 1 also leads to a better concentricity of the pin heater 1, even if the layers are not arranged exactly concentrically, but slightly eccentrically due to manufacturing tolerances ,
• Another advantage of the essentially rotationally symmetrical arrangement of the layers 10, 15, 16, 20 of the pin heater 1 according to FIG. 2 is that a position of the insulation layer 10 that is slightly eccentric due to manufacturing tolerances does not lead to any change in the electrical resistance behavior of the pin heater 1, since both the Cross sectional area the second conductive layer 20, and the cross-sectional area of the first conductive layer 15, 16 is not changed.
• FIGS. 3 and 4 in which the same reference numerals designate the same elements as in the first exemplary embodiment according to FIGS. 1 and 2, the pin heater in FIG. 3 is again shown in a longitudinal section.
• Figure 4 shows the cross section of the pin heater 1 along a section line B-B drawn in Figure 3.
• the first conductive layer 15, 16 in the region of the tip 40 of the pin heater 1 on the combustion chamber side comprises the first ceramic material 16 and otherwise the second ceramic material 15, the first ceramic material 16 having a higher specific electrical resistance than the second ceramic material 15 ,
• the proportion of the insulation layer 10 in the total cross section increases, while the proportion of the two guide layers 15, 16, 20 in the total cross section decreases , According to FIG.
• the cross-sectional area of the insulation layer 10 can remain the same, as shown in FIG. 3.
• the cross-sectional area of the second conductive layer 20 can also remain the same, as shown in FIG. 3. In this case, as shown in FIG. 3, the overall cross section toward the tip 40 of the pin heater 1 on the combustion chamber side is reduced.
• the cross-section of the first conductive layer 15, 16 can be reduced toward the tip 40 of the pin heater 1 on the combustion chamber side This is accompanied by an increase in the cross-sectional area of the insulation layer 10 toward the tip 40 on the combustion chamber side, so that the overall cross section of the pin heater 1 remains essentially the same over its entire length.
• the aim of these measures is to increase the electrical resistance in the region of the tip 40 of the pin heater 1 on the combustion chamber side in order to concentrate the heating power there.
• the cross section shown in FIG. 4 along the section line BB lies outside the region of the cross-sectional constriction of the pin heater 1, but also applies qualitatively to the region of the cross-sectional constriction shown in FIG. 3 in the region of the tip 40 on the combustion chamber side.
• the first conductive layer 15, 16, the second conductive layer 20 and the insulation layer 10 are arranged essentially concentrically to one another, but are no longer rotationally symmetrical. This is because the insulation layer 10 in the second embodiment has a preferred direction 35 in cross section in comparison to the insulation layer 10 in the first embodiment, in which it is more extensive compared to at least one other direction.
• the insulation layer 10 is extended in the preferred direction 35 to the outer edge of the pin heater 1, so that the first conductive layer 15, 16 is divided into two outside the region of the tip 40 on the combustion chamber side.
• the insulation layer 10 does not have to be extended in its preferred direction 35 to the edge of the pin heater 1, so that the aforementioned division of the first conductive layer 15, 16 is not absolutely necessary.
• the preferred direction 35 for the insulation layer 10 there is the advantage that bending of the insulation layer 10 when it is connected to the first conductive layer 15, 16 during the manufacturing process of the pin heater 1 can be largely avoided, so that the pin heater 1 is made mechanically more robust overall can than this in the rotationally symmetrical arrangement according to the first embodiment is possible.
• the second conductive layer 20 can also have a preferred direction 45 in cross section, in which it is more extensive than at least one other direction. In this way, bending of the second conductive layer 20 when connecting to the insulation layer 10 in the manufacture of the pin heater 1 can be largely prevented. This measure also increases the mechanical robustness of the pin heater 1 compared to the rotationally symmetrical arrangement according to the first exemplary embodiment. If both bending of the second conductive layer 20 and the insulation layer 10 are to be avoided in the manufacture of the pin heater 1, both the insulation layer 10 and the second conductive layer 20 should have a preferred direction in cross section in which they are compared to at least one other direction is more extensive.
• the insulation layer 10 has the preferred direction 35, the electrical insulation effect can be increased in this direction and the formation of leakage currents between the second conductive layer 20 and the first conductive layer 15, 16 can be considerably reduced.
• the shape of the pin heater 1 can be realized as an inexpensive large-scale production process by means of an injection molding process, by means of a transfer molding process or by means of a slip casting process.
• a composite ceramic can be used, which in the case of the two conductive layers 15, 16, 20 is designed as a matrix with conductive fillers. This enables higher operating temperatures, higher corrosion resistance and a longer service life to be achieved.
• an external heater is implemented with the first conductive layer 15, 16, the heating-up time of the pin heater can be shortened and, for example, an immediate start of the internal combustion engine can also be achieved even at -20 ° C.
• the manufacturing outlay can be reduced.
• the diameter of the pin heater 1 can be, for example, approximately 3.3 mm.
• the glow plug 5 with the pin heater 1 presented here can be installed, for example, in an M8 housing of the cylinder head.
• the external heater realized by the first conductive layer 15, 16, starting from -20 ° C a temperature of 1000 ° C and a steady temperature of over 1200 ° C can be reached within a few seconds.
• the heating-up time can be reduced if, as described, the resistance of the first ceramic material 16 is increased in relation to the resistance of the second ceramic material 15 and the resistance of the second conductive layer 20. This measure can also be used to increase the steady-state temperature.
• the second conductive layer 20 is guided inside the insulation layer 10, as is also the case in the first exemplary embodiment.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Resistance Heating (AREA)
• Combustion Methods Of Internal-Combustion Engines (AREA)

Applications Claiming Priority (3)

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• 2001
  • 2001-11-09 DE DE10155230A patent/DE10155230C5/de not_active Expired - Fee Related
• 2002
  • 2002-10-31 JP JP2003542839A patent/JP2005509123A/ja not_active Withdrawn
  • 2002-10-31 KR KR10-2004-7006939A patent/KR20040062621A/ko not_active Application Discontinuation
  • 2002-10-31 WO PCT/DE2002/004048 patent/WO2003040624A1/de not_active Application Discontinuation
  • 2002-10-31 US US10/466,007 patent/US6949717B2/en not_active Expired - Fee Related
  • 2002-10-31 PL PL02368673A patent/PL368673A1/xx not_active Application Discontinuation
  • 2002-10-31 HU HU0302543A patent/HUP0302543A2/hu unknown
  • 2002-10-31 CN CNA028062787A patent/CN1496465A/zh active Pending
  • 2002-10-31 EP EP02779194A patent/EP1446613A1/de not_active Ceased
  • 2002-11-05 TW TW091132562A patent/TWI263758B/zh not_active IP Right Cessation

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