EP3396249B1 - Bougie de préchauffage - Google Patents

Bougie de préchauffage Download PDF

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Publication number
EP3396249B1
EP3396249B1 EP18165735.4A EP18165735A EP3396249B1 EP 3396249 B1 EP3396249 B1 EP 3396249B1 EP 18165735 A EP18165735 A EP 18165735A EP 3396249 B1 EP3396249 B1 EP 3396249B1
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EP
European Patent Office
Prior art keywords
heat
generation
section
cross
fusion zone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP18165735.4A
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German (de)
English (en)
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EP3396249A1 (fr
Inventor
Hirofumi Okada
Makoto EJIRI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Niterra Co Ltd
Original Assignee
NGK Spark Plug Co Ltd
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Priority claimed from JP2017249214A external-priority patent/JP6965153B2/ja
Application filed by NGK Spark Plug Co Ltd filed Critical NGK Spark Plug Co Ltd
Publication of EP3396249A1 publication Critical patent/EP3396249A1/fr
Application granted granted Critical
Publication of EP3396249B1 publication Critical patent/EP3396249B1/fr
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    • 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
    • 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
    • F23Q2007/004—Manufacturing or assembling methods

Definitions

  • the present invention relates to a glow plug.
  • Patent Document 1 a glow plug having a heat generation element which contains tungsten (W) as a main component is proposed.
  • the heat generation element is inserted into a fusion zone at a forward end of a tubular member (tube) to thereby be joined to the tubular member.
  • the reason for such a joining form is as follows: since the heat generation element which contains W as a main component is high in melting point, the heat generation element hardly melts, whereas the tubular member melts to form the fusion zone. Further, according to Patent Document 1, in the fusion zone, the coiled heat generation element reduces in diameter toward its forward end. Patent Document 1 forms the basis for the preamble of claim 1.
  • a forward end of a tubular member is melted and then solidified to thereby fix a forward end of a coiled heat generation element in a fusion zone.
  • the forward end of the tubular member in which the forward end of the heat generation element is disposed is melted; then, the melted forward end is solidified, thereby forming the fusion zone into which the forward end of the heat generation element is inserted.
  • the fusion zone is solidified such that solidification starts from its periphery and gradually proceeds toward the center.
  • the forward end of the heat generation element is fixed in a region around the center of the fusion zone.
  • the region around the center of the fusion zone is the latest to undergo solidification. Therefore, before the heat generation element is fixed, the heat generation element may move or be offset from the center.
  • the fusion zone contracts in the course of solidification, when the periphery of the fusion zone is solidified, tensile stress is applied to the center of the fusion zone; consequently, the heat generation element is apt to move. As a result, the heat generation element may fail to be fixed at a desired position.
  • the present invention has been conceived to solve the above problem and can be embodied in the following modes.
  • the gap along the axial line between the rearmost end of the first heat-generation-element cross section and the forwardmost end of the third heat-generation-element cross section is small, a portion of the heat generation element having the third heat-generation-element cross section may be caught in the fusion zone and thus may fail to yield the function of the heat generation element.
  • the portion of the heat generation element having the third heat-generation-element cross section is less likely to be caught in the fusion zone.
  • the gap along the axial line between the rearmost end of the second heat-generation-element cross section and the forwardmost end of the fourth heat-generation-element cross section is small, a portion of the heat generation element having the fourth heat-generation-element cross section may be caught in the fusion zone and thus may fail to yield the function of the heat generation element.
  • the portion of the heat generation element having the fourth heat-generation-element cross section is less likely to be caught in the fusion zone.
  • the glow plug can provide high heating-up temperature.
  • FIG. 1 shows a glow plug 10.
  • the glow plug 10 includes a sheath heater (heat generation device) 800 for generating heat and functions as a heat source for assisting ignition at startup of an internal combustion engine (not shown) such as a diesel engine.
  • the glow plug 10 includes the sheath heater 800, an axial rod 200, and a metallic shell 500. These component members of the glow plug 10 are assembled together along the axial direction OD of the glow plug 10.
  • FIG. 1 shows an external structure on the right side of an axial line O and a sectional structure on the left side of the axial line O.
  • a side toward the sheath heater 800 in the glow plug 10 is called the "forward side”
  • a side toward an engagement member 100 is called the "rear side.”
  • the metallic shell 500 is a tubular member formed of carbon steel.
  • the metallic shell 500 holds the sheath heater 800 at a forward end portion thereof.
  • the metallic shell 500 holds the axial rod 200 at a rear end portion thereof through an insulation member 410 and an O-ring 460.
  • the position of the insulation member 410 along the axial line O is fixed as a result of a ring 300 in contact with the rear end of the insulation member 410 being crimped to the axial rod 200.
  • a portion of the axial rod 200 extending from the insulation member 410 to the sheath heater 800 is disposed in an axial hole 510 of the metallic shell 500.
  • the axial hole 510 is a through hole formed along the axial line O and is greater in diameter than the axial rod 200.
  • the metallic shell 500 further includes a tool engagement portion 520 and an external thread portion 540.
  • a tool (not shown) is engaged with the tool engagement portion 520 of the metallic shell 500 for attaching and detaching the glow plug 10.
  • the external thread portion 540 meshes with an internal thread formed in an internal combustion engine (not shown).
  • the axial rod 200 is a circular columnar (rodlike) member formed of an electrically conductive material. While being inserted through the axial hole 510 of the metallic shell 500, the axial rod 200 is disposed in position along the axial line O.
  • the axial rod 200 includes a forward end portion 210 formed at the forward end side and an external thread portion 290 provided at the rear end side. The forward end portion 210 is inserted into the sheath heater 800. The external thread portion 290 protrudes rearward from the metallic shell 500. The engagement member 100 meshes with the external thread portion 290.
  • FIG. 2 is a sectional view showing the structure of a sheath heater 800 in detail.
  • the sheath heater 800 includes a sheath tube 810, a heat generation coil 820, a rear coil 830, and an insulator 870.
  • the heat generation coil 820 is also called the "forward end coil.”
  • the heat generation coil 820 corresponds to the coiled heat generation element of the present invention.
  • the sheath tube 810 is a tubular member extending in the axial direction OD and having a closed forward end and corresponds to the tubular member of the present invention.
  • the sheath tube 810 accommodates therein the heat generation coil 820, the rear coil 830, and the insulator 870.
  • the sheath tube 810 includes a side portion 814 extending in the axial direction OD, a forward end portion 813 connected to the forward end of the side portion 814 and curved outward, and a rear end portion 819 opening in a direction opposite the forward end portion 813.
  • the forward end portion 210 of the axial rod 200 is inserted into the sheath tube 810 from the rear end portion 819.
  • the sheath tube 810 is electrically insulated from the axial rod 200 by a packing 600 and the insulator 870. Meanwhile, the sheath tube 810 is in contact with the metallic shell 500 to thereby be electrically connected to the metallic shell 500.
  • the sheath tube 810 is formed of, for example, austenitic stainless steel which contains iron (Fe), chromium (Cr), and carbon (C), or a nickel (Ni)-based alloy such as INCONEL 601 (INCONEL is a registered trademark) or Alloy602 (corresponding to DIN2.4633 alloy specified by German Industrial Standard (DIN)).
  • the insulator 870 is formed of powder of an electrical insulation material.
  • magnesium oxide (MgO) powder is used as the insulator 870.
  • the insulator 870 is filled into (disposed in) a gap which remains in the sheath tube 810 as a result of disposition of the axial rod 200, the heat generation coil 820, and the rear coil 830 in the sheath tube 810, thereby providing electrical insulation in the gap.
  • the heat generation coil 820 is disposed in the sheath tube 810 along the axial direction OD and generates heat by energization thereof.
  • the heat generation coil 820 includes a forward end portion 822, which is a forward coil end portion, and a rear end portion 829, which is a rear coil end portion.
  • the forward end portion 822 is located in the forward end portion 813 of the sheath tube 810 and electrically connected to the sheath tube 810.
  • the rear end portion 829 is electrically connected to the rear coil 830 through a connection 840 formed as a result of welding of the heat generation coil 820 and the rear coil 830.
  • the main component of the heat generation coil 820 is tungsten (W).
  • the main component is a substance whose content (% by mass) is 50% by mass or higher.
  • the tungsten (W) content of the heat generation coil 820 is 99% by mass or higher.
  • the wire diameter of the heat generation coil 820 is preferably 0.1 mm to 0.25 mm, more preferably 0.15 mm to 0.25 mm, and particularly preferably 0.18 mm to 0.25 mm.
  • the heat generation coil 820 contains, as a main component, tungsten (W) having a smaller specific resistance. However, by imparting a wire diameter of 0.1 mm to 0.25 mm to the heat generation coil 820, the heat generation coil 820 can generate sufficient heat.
  • the heat generation coil 820 reduces in wire diameter, its rigidity lowers; as a result, in the course of solidification of a fusion zone 891, which will be described later, due to subjection to tensile stress, the heat generation coil 820 tends to be offset from the center without being fixed at a desired position. According to the present embodiment, since the heat generation coil 820 is positioned in a region that solidifies at an early stage of solidification (the periphery of the fusion zone 891), even the heat generation coil 820 having such a small wire diameter can be fixed at a desired position without being offset from the center.
  • the rear coil 830 includes a forward end portion 831, which is a forward coil end portion, and a rear end portion 839, which is a rear coil end portion.
  • the forward end portion 831 is welded to the rear end portion 829 of the heat generation coil 820 to thereby be electrically connected to the heat generation coil 820.
  • the rear end portion 839 is joined to the forward end portion 210 of the axial rod 200 to thereby be electrically connected to the axial rod 200.
  • the rear coil 830 is formed of, for example, a nickel (Ni)-chromium (Cr) alloy or an iron (Fe)-chromium (Cr)-aluminum (Al) alloy.
  • the resistance R 20 of the glow plug 10 at 20°C is 0.6 ⁇ or less.
  • the resistance R 20 of the glow plug 10 at 20°C is the sum of the resistance of the heat generation coil 820 at 20°C and the resistance of the rear coil 830 at 20°C.
  • the resistance R 20 of the glow plug 10 at 20°C is 0.4 ⁇ .
  • a resistance ratio R1 which is the ratio of the resistance R1 1000 of the heat generation coil 820 at 1,000°C to the resistance R1 20 of the heat generation coil 820 at 20°C and a resistance ratio R2 which is the ratio of the resistance R2 1000 of the rear coil 830 at 1,000°C to the resistance R2 20 of the rear coil 830 at 20°C satisfy a relation of R1 > R2.
  • FIG. 3 is a sectional view showing the forward end portion 813 of the sheath tube 810 and its periphery. The forward end of the sheath tube 810 is closed with the fusion zone 891.
  • FIG. 3 shows a cross section of the glow plug 10 taken along the axial line O of the glow plug 10 such that the same number of cross sections of the heat generation coil 820 appear in the fusion zone 891 on opposite sides of the axial line O.
  • the left side of the axial line O is taken as one side of the axial line O, and the right side is taken as the other side.
  • two cross sections of the heat generation coil 820 appear in the fusion zone 891 on each of opposite sides of the axial line O.
  • FIG. 3 shows the heat generation coil 820, the sheath tube 810, and the insulator 870 which are cut along a plane passing through the axial line O.
  • the fusion zone 891 contains columnar crystals (dendrite), whereas a base metal portion 893 other than the fusion zone 891 has a microstructure different from that of the fusion zone 891.
  • the microstructure of the base metal portion 893 include a fibrous microstructure and a forged microstructure.
  • the microstructure can be identified as columnar crystals, a fibrous microstructure, or a forged microstructure by a publicly known metal microstructure observation method; specifically, by electrolytic etching of a cut surface in an oxalate solution (JIS G 5071 2012), for example.
  • the forward end portion 822 of the heat generation coil 820 is inserted into the fusion zone 891.
  • the rearmost one of the cross sections of the heat generation coil 820 appearing in the fusion zone 891 on one side of the axial line O will be referred to as a first heat-generation-element cross section 901.
  • the rearmost one of the cross sections of the heat generation coil 820 appearing in the fusion zone 891 on the other side of the axial line O will be referred to as a second heat-generation-element cross section 902.
  • the forwardmost one of the cross sections of the heat generation coil 820 appearing externally of the fusion zone 891 on the one side of the axial line O will be referred to as a third heat-generation-element cross section 903.
  • the forwardmost one of the cross sections of the heat generation coil 820 appearing externally of the fusion zone 891 on the other side of the axial line O will be referred to as a fourth heat-generation-element cross section 904.
  • the third heat-generation-element cross section 903 and the fourth heat-generation-element cross section 904 are located away from the fusion zone 891.
  • a cross section which is one of the cross sections of the heat generation element 820 appearing externally of the fusion zone 891 on the one side of the axial line O and which is located immediately rearward of the third heat-generation-element cross section 903 will be referred to as a fifth heat-generation-element cross section 905.
  • a cross section which is one of the cross sections of the heat generation element 820 appearing externally of the fusion zone 891 on the other side of the axial line O and which is located immediately rearward of the fourth heat-generation-element cross section 904 will be referred to as a sixth heat-generation-element cross section 906.
  • a radial distance F between the radially outermost end of the first heat-generation-element cross section 901 and the radially innermost end of the base metal portion 893 is 0.200 mm or less.
  • the distance F between a straight line L1 extending axially from the radially outermost end of the first heat-generation-element cross section 901 and a straight line L2 extending axially from the radially innermost end of the base metal portion 893 is 0.200 mm or less.
  • the distance F is 0.180 mm or less.
  • a radial distance G between the radially outermost end of the second heat-generation-element cross section 902 and the radially innermost end of the base metal portion 893 is 0.200 mm or less.
  • the distance G between a straight line L3 extending axially from the radially outermost end of the second heat-generation-element cross section 902 and a straight line L4 extending axially from the radially innermost end of the base metal portion 893 is 0.200 mm or less.
  • the distance G is 0.180 mm or less.
  • the following actions and effects are yielded by specifying, as mentioned above, the distance relation between the first heat-generation-element cross section 901 and the base metal portion 893 and the distance relation between the second heat-generation-element cross section 902 and the base metal portion 893.
  • a portion of the heat generation coil 820 disposed within the fusion zone 891 is more in contiguity with the base metal portion 893. Therefore, as a result of the heat generation coil 820 being positioned in a portion of the fusion zone 891 (the periphery of the fusion zone 891) which solidifies at an early stage of solidification, in the course of solidification of the fusion zone 891, the heat generation coil 820 is fixed at a desired position without movement or offsetting.
  • the temperature distribution around the glow plug 10 in the circumferential direction can be uniformized, whereby the startability of an engine can be stabilized.
  • the heat generation coil 820 is not offset from the center, contact of the side of the heat generation coil 820 with the sheath tube 810 is restrained to thereby reduce the occurrence of short circuit, so that durability is improved.
  • improvement of durability as a result of reduction in occurrence of short circuit by virtue of the above distance relations will be described in detail in the after-mentioned section "Examples.”
  • the absolute value of the difference between the distance F and the distance G is 0.150 mm or less. If the absolute value of the difference between the distance F and the distance G is 0.150 mm or less, offsetting of the heat generation coil 820 is further restrained, whereby durability is further improved.
  • the first heat-generation-element cross section 901, the second heat-generation-element cross section 902, the third heat-generation-element cross section 903, and the fourth heat-generation-element cross section 904 satisfy the following relations.
  • a region A represents a region between two straight lines M1 extending along the axial line O from radially opposite ends of the third heat-generation-element cross section 903.
  • a region B represents a region between two straight lines N1 extending along the axial line O from radially opposite ends of the first heat-generation-element cross section 901.
  • half or more of the region A overlaps the region B.
  • 65% or more of the region A overlaps the region B, and particularly preferably, 75% or more of the region A overlaps the region B.
  • a region C represents a region between two straight lines M2 extending along the axial line O from radially opposite ends of the fourth heat-generation-element cross section 904.
  • a region D represents a region between two straight lines N2 extending along the axial line O from radially opposite ends of the second heat-generation-element cross section 902.
  • half or more of the region C overlaps the region D. More preferably, 65% or more of the region C overlaps the region D, and particularly preferably, 75% or more of the region C overlaps the region D.
  • the diameter of the heat generation coil 820 inside the fusion zone 891 is smaller than that outside the fusion zone 891.
  • a portion of the heat generation coil 820 that is to be fixed to the fusion zone 891 approaches a central portion of the sheath tube 810 (the center of the fusion zone 891) and thus is located away from the base metal portion 893 (the periphery of the fusion zone 891).
  • the heat generation coil 820 may fail to be fixed at a desired position.
  • the diameter of the heat generation coil 820 is hardly reduced within the fusion zone 891 as compared with the diameter of the heat generation coil 820 measured outside the fusion zone 891, a portion of the fusion zone 891 around the heat generation coil 820 solidifies at an early stage of solidification, so that the heat generation coil 820 is easily fixed at a desired position.
  • the first heat-generation-element cross section 901, the second heat-generation-element cross section 902, the third heat-generation-element cross section 903, the fourth heat-generation-element cross section 904, the fifth heat-generation-element cross section 905, and the sixth heat-generation-element cross section 906 satisfy the following relations.
  • a gap a1 along the axial line O between the first heat-generation-element cross section 901 and the third heat-generation-element cross section 903 is greater than a gap b1 along the axial line O between the third heat-generation-element cross section 903 and the fifth heat-generation-element cross section 905.
  • a gap a2 along the axial line O between the second heat-generation-element cross section 902 and the fourth heat-generation-element cross section 904 is greater than a gap b2 along the axial line O between the fourth heat-generation-element cross section 904 and the sixth heat-generation-element cross section 906.
  • the gap a1 between the first heat-generation-element cross section 901 and the third heat-generation-element cross section 903 is small, a portion of the heat generation coil 820 having the third heat-generation-element cross section 903 may be caught in the fusion zone 891 and thus may fail to yield the function of the heat generation element.
  • the gap a1 is greater than the gap b1, the portion of the heat generation coil 820 having the third heat-generation-element cross section 903 is less likely to be caught in the fusion zone 891.
  • the gap a2 between the second heat-generation-element cross section 902 and the fourth heat-generation-element cross section 904 is small, a portion of the heat generation coil 820 having the fourth heat-generation-element cross section 904 may be caught in the fusion zone 891 and thus may fail to yield the function of the heat generation element.
  • the gap a2 is greater than the gap b2, the portion of the heat generation coil 820 having the fourth heat-generation-element cross section 904 is less likely to be caught in the fusion zone 891.
  • the glow plug 10 can provide high heating-up temperature.
  • FIG. 6 is a flowchart showing a method of manufacturing the glow plug 10.
  • the heat generation coil 820 and the axial rod 200 are welded together (step S10).
  • the heat generation coil 820 and the rear coil 830 are welded together; further, the rear end portion 839 of the rear coil 830 and the forward end portion 210 of the axial rod 200 are welded together.
  • the forward end portion 822 of the heat generation coil 820 and the forward end portion 813 of the sheath tube 810 are welded together (step S20).
  • Step S20 is also called the "welding process.”
  • FIGS. 7(a) and 7(b) are explanatory views showing a welding process in step S20.
  • a sheath tube 810P which includes a forward end portion 813P having an opening 815 and which is shaped such that diameter gradually reduces toward the opening 815.
  • the forward end portion 822 of the heat generation coil 820 is disposed inside the forward end portion 813P of the prepared sheath tube 810P such that a second turn 822P of the heat generation coil 820 comes into contact with the sheath tube 810P ( FIG. 7(a) ).
  • the forward end portion 813P is melted by, for example, arc welding from outside and then is solidified to close the opening 815
  • the forward end portion 822 of the heat generation coil 820 and the forward end portion 813 of the sheath tube 810 are welded together ( FIG. 7(b) ).
  • the forward end portion 822 of the heat generation coil 820 is surrounded by and embedded in the forward end portion 813 of the sheath tube 810.
  • output of the welding machine, welding time, etc. are adjusted such that the heat generation coil 820 and the sheath tube 810 are welded together at a temperature lower than the melting point of the heat generation coil 820 and higher than the melting point of the sheath tube 810.
  • the thickness of an alloy portion formed of the alloy is 10 ⁇ m or less.
  • the thickness of the alloy portion can be calculated by detecting the alloy portion through analysis of a region in the vicinity of the boundary between the forward end portion 822 of the heat generation coil 820 and the forward end portion 813 of the sheath tube 810 by use of, for example, EPMA (Electron Probe Micro Analyzer).
  • EPMA Electro Probe Micro Analyzer
  • the insulator 870 is filled into the sheath tube 810 (step S30).
  • the insulator 870 covers the heat generation coil 820, the rear coil 830, and the axial rod 200 to thereby fill a gap formed in the sheath tube 810, whereby assembly of the sheath heater 800 is completed.
  • swaging is performed on the sheath heater 800 (step S40). Swaging is performed such that striking force is applied to the sheath heater 800 to thereby reduce the diameter of the sheath heater 800, so as to densify the insulator 870 filled into the sheath tube 810.
  • striking force is applied to the sheath heater 800 as a result of swaging, the striking force is transmitted to the interior of the sheath heater 800, thereby densifying the insulator 870.
  • step S50 After swaging is performed on the sheath heater 800, the sheath heater 800 and the metallic shell 500 are combined to thereby assemble the glow plug 10 (step S50), whereby the glow plug 10 is completed.
  • the sheath heater 800 integrated with the axial rod 200 is fixedly press-fitted into the axial hole 510 of the metallic shell 500; the O-ring 460 and the insulation member 410 are fitted to the axial rod 200 at a rear end portion of the metallic shell 500; and the engagement member 100 is meshed with the external thread portion 290 of the axial rod 200 located rearward of the rear end of the metallic shell 500.
  • step S50 aging is performed on the glow plug 10. Specifically, the assembled glow plug 10 is energized so that the sheath heater 800 generates heat, thereby forming an oxide film on the outer surface of the sheath heater 800.
  • Experimental examples 1 to 7 correspond to examples of the present invention, and experimental examples 8 and 9 correspond to comparative examples.
  • the glow plugs 10 of the experimental examples were adjusted in the forward end shape of the heat generation coil 820 so as to adjust the radial distance F between the radially outermost end of the first heat-generation-element cross section 901 and the radially innermost end of the base metal portion 893 and the radial distance G between the radially outermost end of the second heat-generation-element cross section 902 and the radially innermost end of the base metal portion 893.
  • the distance between the base metal portion 893 and the heat generation coil 820 was measured as follows: the offsetting of the heat generation coil 820 from the center was checked before disassembly by use of X rays, and then the sheath heater 800 was sectioned for measurement such that the most offset first heat-generation-element cross section 901 appeared on the one side of the axial line O or such that the most offset second heat-generation-element cross section 902 appeared on the other side of the axial line O.
  • a voltage for increasing the glow plug temperature by 1,000°C in two seconds was applied to the glow plugs 10; then, a voltage for saturating the glow plug temperature at 1,150°C was applied to the glow plugs 10 continuously for 180 seconds. Subsequently, the glow plugs 10 were cooled by wind for 120 seconds for lowering the temperature of the glow plugs 10 to room temperature. With this procedure taken as one cycle, a cycle test was conducted. In the course of the cycle test, the number of cycles at which a short circuit occurred was counted.
  • the temperature was measured at a position located 2 mm from the forward end of the sheath tube 810 by use of a PR thermocouple (platinum-platinum rhodium thermocouple) and a radiation thermometer.
  • PR thermocouple platinum-platinum rhodium thermocouple
  • Table 1 shows the test results. Experimental examples 1 to 7 were free from the occurrence of short circuit within 3,500 cycles. By contrast, experimental examples 8 and 9 suffered the occurrence of short circuit within 3,500 cycles. Therefore, it has been confirmed that durability is improved in the case where the radial distance F between the radially outermost end of the first heat-generation-element cross section 901 and the radially innermost end of the base metal portion 893 and the radial distance G between the radially outermost end of the second heat-generation-element cross section 902 and the radially innermost end of the base metal portion 893 are 0.200 mm or less.
  • experimental examples 1 to 7 experimental examples 1 to 5 in which the absolute value of the difference between the distance F and the distance G was 0.150 mm or less were free from the occurrence of short circuit even at 7,000 cycles. Therefore, it has been confirmed that durability further improves when the absolute value of the difference between the distance F and the distance G is 0.150 mm or less.
  • the reason for the occurrence of short circuit as a result of the durability test is inferred as follows. During the durability test, voids are formed among particles of the charged insulation powder. As a result, in the case of excessive temperature rise of the heat generation coil 820, heat of the heat generation coil 820 melts the sheath tube 810, and the resultant molten metal moves toward the heat generation coil 820, resulting in the occurrence of short circuit.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
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Claims (5)

  1. Bougie de préchauffage (10), comprenant :
    un organe tubulaire (810) dont l'extrémité en avant est fermée avec une zone de fusion (891), et
    un élément de génération de chaleur enroulé (820) disposé dans l'organe tubulaire (810) et contenant W en tant que composant principal,
    dans laquelle l'organe tubulaire (810) a une portion métallique de base (893) raccordée à la zone de fusion (891) et ayant une microstructure différente de celle de la zone de fusion (891) ;
    une portion d'extrémité en avant de l'élément de génération de chaleur (820) est insérée dans la zone de fusion (891) pour ainsi être jointe à l'organe tubulaire (810) ; et
    dans une section transversale de la bougie de préchauffage (10) prise le long d'une ligne axiale (O) de la bougie de préchauffage (10) de telle sorte que le même nombre de sections transversales de l'élément de génération de chaleur (820) apparaissent dans la zone de fusion (891) sur des côtés opposés de la ligne axiale (O),
    caractérisée par
    une distance radiale F entre une extrémité radialement la plus extérieure d'une première section transversale d'élément de génération de chaleur (901) et une extrémité radialement la plus intérieure de la portion métallique de base (893) est 0,200 mm ou moins, la première section transversale d'élément de génération de chaleur étant une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant dans la zone de fusion (891) sur un côté de la ligne axiale (O), la première section transversale d'élément de génération de chaleur étant disposée au moins partiellement à l'intérieur de la zone de fusion (891), et
    une distance radiale G entre une extrémité radialement la plus extérieure d'une deuxième section transversale d'élément de génération de chaleur (902) et une extrémité radialement la plus intérieure de la portion métallique de base (893) est 0,200 mm ou moins, la deuxième section transversale d'élément de génération de chaleur étant une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant dans la zone de fusion (891) sur l'autre côté de la ligne axiale (O), la deuxième section transversale d'élément de génération de chaleur étant disposée au moins partiellement à l'intérieur de la zone de fusion (891).
  2. Bougie de préchauffage selon la revendication 1, dans laquelle la valeur absolue d'une différence entre la distance F et la distance G est 0,150 mm ou moins.
  3. Bougie de préchauffage selon la revendication 1 ou 2, dans laquelle dans la section,
    avec une région A représentant une région entre deux lignes droites (M1) s'étendant le long de la ligne axiale (O) à partir d'extrémités radialement opposées d'une troisième section transversale d'élément de génération de chaleur (903) qui est une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'un côté de la ligne axiale (O) et
    avec une région B représentant une région entre deux lignes droites (N1) s'étendant le long de la ligne axiale (O) à partir d'extrémités radialement opposées de la première section transversale d'élément de génération de chaleur (901),
    la moitié ou plus de la région A chevauche la région B, et
    avec une région C représentant une région entre deux lignes droites (M2) s'étendant le long de la ligne axiale (O) à partir d'extrémités radialement opposées d'une quatrième section transversale d'élément de génération de chaleur (904) qui est une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'autre côté de la ligne axiale (O) et
    avec une région D représentant une région entre deux lignes droites (N2) s'étendant le long de la ligne axiale (O) à partir d'extrémités radialement opposées de la deuxième section transversale d'élément de génération de chaleur (902),
    la moitié ou plus de la région C chevauche la région D.
  4. Bougie de préchauffage selon l'une quelconque des revendications 1 à 3, dans laquelle l'élément de génération de chaleur (820) a un diamètre de fil de 0,1 mm à 0,25 mm.
  5. Bougie de préchauffage selon l'une quelconque des revendications 1 à 4, dans laquelle dans la section,
    avec une troisième section transversale d'élément de génération de chaleur (903) représentant une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'un côté de la ligne axiale (O),
    avec une quatrième section transversale d'élément de génération de chaleur (904) représentant une la plus en arrière des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'autre côté de la ligne axiale (O),
    avec une cinquième section transversale d'élément de génération de chaleur (905) représentant une section transversale qui est une des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'un côté de la ligne axiale (O) et qui est située immédiatement en arrière de la troisième section transversale d'élément de génération de chaleur (903), et
    avec une sixième section transversale d'élément de génération de chaleur (906) représentant une section transversale qui est une des sections transversales de l'élément de génération de chaleur (820) apparaissant extérieurement de la zone de fusion (891) sur l'autre côté de la ligne axiale (O) et qui est située immédiatement en arrière de la quatrième section transversale d'élément de génération de chaleur (904),
    un espace (a1) le long de la ligne axiale (O) entre une extrémité la plus en arrière de la première section transversale d'élément de génération de chaleur (901) et une extrémité la plus en avant de la troisième section transversale d'élément de génération de chaleur (903) est plus grand qu'un espace (b1) le long de la ligne axiale (O) entre une extrémité la plus en arrière de la troisième section transversale d'élément de génération de chaleur (903) et une extrémité la plus en avant de la cinquième section transversale d'élément de génération de chaleur (905), et
    un espace (a2) le long de la ligne axiale (O) entre une extrémité la plus en arrière de la deuxième section transversale d'élément de génération de chaleur (902) et une extrémité la plus en avant de la quatrième section transversale d'élément de génération de chaleur (904) est plus grand qu'un espace (b2) le long de la ligne axiale (O) entre une extrémité la plus en arrière de la quatrième section transversale d'élément de génération de chaleur (904) et une extrémité la plus en avant de la sixième section transversale d'élément de génération de chaleur (906).
EP18165735.4A 2017-04-24 2018-04-04 Bougie de préchauffage Active EP3396249B1 (fr)

Applications Claiming Priority (2)

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JP2017085046 2017-04-24
JP2017249214A JP6965153B2 (ja) 2017-04-24 2017-12-26 グロープラグ

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Publication number Priority date Publication date Assignee Title
JP4288850B2 (ja) * 2000-03-17 2009-07-01 株式会社デンソー グロープラグの製造方法
DE102005043415A1 (de) * 2005-09-13 2007-03-15 Robert Bosch Gmbh Glühstiftkerze
DE102013212283A1 (de) 2013-06-26 2014-12-31 Robert Bosch Gmbh Glührohr für eine regelbare Glühstiftkerze

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