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The spark plug has a top end portion of a main metal shell that is almost cylindrical on an outer circumferential face without having a plug attaching external thread screwed into the cylinder head. Further, the plug hole formed in the cylinder head has a top end counterpart corresponding to the top

The spark plug has a top end portion of a main metal shell that is almost cylindrical on an outer circumferential face without having a plug attaching external thread screwed into the cylinder head. Further, the plug hole formed in the cylinder head has a top end counterpart corresponding to the top end portion of the main metal shell. And in the mounting structure of the spark plug into the cylinder head (plug hole), the clearance amount (φD-φd) satisfies a relation φD-φd≤0.15 (unit: mm) where the outer diameter of the top end portion of the main metal shell is φd and the hole diameter of the top end counterpart of the plug hole is φD.

대표청구항 ▼

The spark plug has a top end portion of a main metal shell that is almost cylindrical on an outer circumferential face without having a plug attaching external thread screwed into the cylinder head. Further, the plug hole formed in the cylinder head has a top end counterpart corresponding to the top

The spark plug has a top end portion of a main metal shell that is almost cylindrical on an outer circumferential face without having a plug attaching external thread screwed into the cylinder head. Further, the plug hole formed in the cylinder head has a top end counterpart corresponding to the top end portion of the main metal shell. And in the mounting structure of the spark plug into the cylinder head (plug hole), the clearance amount (φD-φd) satisfies a relation φD-φd≤0.15 (unit: mm) where the outer diameter of the top end portion of the main metal shell is φd and the hole diameter of the top end counterpart of the plug hole is φD. 1. A flat commutator for an electrical machine, comprising a support body made of an insulating molding compound, a plurality of conductor segments and an equal number of carbon segments, which are disposed at the ends and are connected in electrically conductive relationship to the conductor segments, wherein each of the conductor segments is provided with a thick-walled terminal region disposed on the periphery of the support body, a contact region, which is also thick-walled, disposed between the support body and the associated carbon segment and a thin-walled transition region disposed between the terminal region and the contact region, wherein the uniformly thin-wailed transition regions of the conductor segments are oriented with substantially radial extent relative to the commutator axis and are attached to the contact regions of the conductor segments at some distance from the carbon segments, a molding-compound layer being disposed in each case between the transition regions of the conductor segments on the one hand and the carbon segments on the other hand. 2. A flat commutator according to claim 1, wherein the wall thickness of the transition regions of the conductor segments is less than 60% of the wall thickness of the contact regions. 3. A flat commutator according to claim 1, wherein the terminal regions extend over at least 65% of the periphery of the flat commutator. 4. A flat commutator according to claim 1, wherein the molding-compound layer extends in the region between the terminal regions and the carbon segments. 5. A flat commutator according to claim 1, wherein the axial thickness of the molding-compound layer is at least 0.5 mm. 6. A flat commutator according to claim 1, wherein the radial outer faces of the contact regions are disposed radially inside the radial outer faces of the carbon segments by an amount that ranges between 0.5 and 1.5 times the axial thickness of the carbon segments. 7. A flat commutator according to claim 1, wherein the radial inner faces of the contact regions are disposed radially outside the radial inner faces of the carbon segments by an amount that ranges between 0.25 and 1.0 times the axial thickness of the carbon segments. 8. A flat commutator according to claim 1, wherein contact lugs chamfered at the end are disposed on the terminal regions, with the chamfers facing the peripheral faces of the terminal regions. 9. A flat commutator according to claim 1, wherein the wall thickness of the contact regions of the conductor segments is at least 0.4 times the extent of the contact regions in peripheral direction. 10. A flat commutator according to claim 1, wherein the contact regions of the conductor segments bear in electrically conductive relationship over their entire surface against the contact areas disposed on the end faces of the carbon segments. 11. A flat commutator according to claim 10, wherein the contact areas are surrounded at least partly by frame-like raised portions projecting from the end face of the carbon segments. 12. A flat commutator according to claim 11, wherein the area of connection of the carbon segments to the support body in the region of the end faces of the carbon segments and of the raised portions facing away from the running surfaces corresponds to 50 to 70% of the running surface of the carbon segments. 13. A flat commutator according to claim 1, wherein the extent of the transition regions of the conductor segments in the peripheral direction is not greater than the extent of the contact regions in the peripheral direction. 14. A flat commutator according to claim 10, wherein an electrically conductive contact material is accommodated in the region of the contact areas between the contact regions of the conductor segments and the carbon segments. 15. A flat commutator according to claim 1, wherein each carbon segment is covered at its radially outer peripheral face by a molding-compound jacket of the support body. 16. A flat commutator ac cording to claim 15, wherein the terminal regions of the conductor segments are provided with an axial groove which extends at least partly in peripheral direction and in which there engages a rib of the molding-compound jacket. 17. A flat commutator according to claim 15, wherein the terminal regions of the conductor segments project radially beyond the outer peripheral faces of the molding-compound jacket. 18. A flat commutator according to claim 15, wherein interlocking connections are provided in each case between the outer peripheral faces of the carbon segments and the molding-compound jackets. 19. A flat commutator according to claim 18, wherein the interlocking connection is formed as a corrugated structure. 20. A flat commutator according to claim 1, wherein the support body covers the radially inner peripheral faces of the carbon segments while forming interlocking connections. 21. A flat commutator according to claim 1, wherein the carbon segments are made with stepped structure on their outer peripheral edges facing the conductor segments. 22. A conductor blank for use in the flat commutator of claim 1, comprising a plurality of conductor segments, which are disposed around an axis, each of which is provided with a thick-walled terminal region disposed at the periphery of the conductor blank, with a contact region, which is also thick-walled, disposed at the end faces, and with a thin-walled transition region disposed between the terminal region and the contact region, wherein each of the two conductor segments are connected to one another via a bridging part and in that the uniformly thin transition regions of the conductor segments are oriented with substantially radial extent relative to the axis and are attached to the contact regions at some distance from the end faces thereof. 23. A conductor blank according to claim 22, wherein the bridging parts are disposed between the terminal regions of two neighboring conductor segments. 24. A conductor blank according to claim 23, wherein the bridging parts and the terminal regions of the conductor segments have the same axial extent and, via connecting webs, are connected to one another along their entire axial extent. 25. A conductor blank according to claim 24, wherein the wall thickness of the connecting webs is considerably smaller than the wall thickness of the bridging parts. 26. A conductor blank according to claim 23, wherein the distance of the radially inner peripheral faces of the bridging parts from the commutator axis is at least equal to or slightly larger than the distance of the radially outer peripheral faces of the terminal regions of the conductor segments from the commutator axis. 27. A conductor blank according to claim 22, wherein anchoring parts, which protrude from the contact regions in a direction substantially parallel to the axis, are provided at the radially inner ends of the contact regions of the conductor segments. 28. A conductor blank according to claim 27, wherein the anchoring parts are provided at their radially outer peripheral faces with notches. 29. A conductor blank according to claim 22, wherein the extent of the transition regions of the conductor segments in peripheral direction is not greater than the extent of the contact regions in peripheral direction. 30. An annular carbon disk for use in the production of a flat commutator according to claim 1, wherein there is provided, on an end face, a plurality of completely or partly closed frame-like raised portions, which project from the end face of the annular carbon disk and surround contact areas. 31. An annular carbon disk according to claim 30, wherein the frame-like raised portions have a closed periphery, wherein there is provided a solderable metal layer, which is confined to the contact areas and which comprises metal particles pressed into the annular carbon disk and then sintered. 32. An annular carbon disk according to claim 30, wherein the frame-like raised portion