(19)
(11) EP 0 607 872 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.04.1995 Bulletin 1995/16

(43) Date of publication A2:
27.07.1994 Bulletin 1994/30

(21) Application number: 94100446.7

(22) Date of filing: 13.01.1994
(51) International Patent Classification (IPC)5: F23Q 7/00
(84) Designated Contracting States:
DE FR IT

(30) Priority: 14.01.1993 JP 22011/93

(71) Applicant: NIPPONDENSO CO., LTD.
Kariya-city Aichi-pref., 448 (JP)

(72) Inventors:
  • Makino, Sigeharu
    Toyoake-shi, Aichi-ken (JP)
  • Koyama, Taiji
    Toyohashi-shi, Aichi-ken (JP)
  • Tsuji, Nobuyuki
    Hoi-gun, Aichi-ken (JP)

(74) Representative: Bühling, Gerhard, Dipl.-Chem. et al
Patentanwaltsbüro Tiedtke-Bühling-Kinne & Partner Bavariaring 4
80336 München
80336 München (DE)


(56) References cited: : 
   
       


    (54) Glow plug for diesel engine


    (57) A glow plug for a diesel engine is provided which includes generally a heating coil (1). The heating coil is provided with a first resistance element (11) and a second resistance element (12) connected in series with the first resistance element and having a resistance temperature coefficient positively higher than that of the first resistance element. The second resistance element (12) is made of a Co-Fe alloy whose compositions fall in a range where a change in phase from a body-centered cubic lattice arrangement to a face-centered cubic lattice arrangement does not occur and a change in phase from a close-packed hexagonal lattice arrangement to the face-centered cubic lattice arrangement does not occur even when the second resistance element is subjected to a temperature change from a given room temperature to 1000°C. The first resistance element (11) is welded at its end to an end of the second resistance element (12) to form a connection therebetween which consists of part of material forming the first resistance element and part of the Co-Fe alloy forming the second resistance element (12), the material forming the first resistance element (11) being so selected as to prevent compositions of the Co-Fe alloy in the connection from changing in phase from the body-centered cubic lattice arrangement to the face-centered cubic lattice arrangement and from the close-packed hexagonal lattice arrangement to the face-centered cubic lattice arrangement.






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