EP0240650A1 - Glühkerze mit zwei Glühwendeln für Dieselmotoren - Google Patents

Glühkerze mit zwei Glühwendeln für Dieselmotoren Download PDF

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Publication number
EP0240650A1
EP0240650A1 EP87100292A EP87100292A EP0240650A1 EP 0240650 A1 EP0240650 A1 EP 0240650A1 EP 87100292 A EP87100292 A EP 87100292A EP 87100292 A EP87100292 A EP 87100292A EP 0240650 A1 EP0240650 A1 EP 0240650A1
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EP
European Patent Office
Prior art keywords
sheath
spirals
glow plug
lenght
spiral
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.)
Granted
Application number
EP87100292A
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English (en)
French (fr)
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EP0240650B1 (de
Inventor
Mario Turri
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B 80 SRL
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B 80 SRL
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Publication date
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=26326072&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0240650(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Priority claimed from IT19099/86A external-priority patent/IT1204761B/it
Application filed by B 80 SRL filed Critical B 80 SRL
Publication of EP0240650A1 publication Critical patent/EP0240650A1/de
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Publication of EP0240650B1 publication Critical patent/EP0240650B1/de
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Classifications

    • 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

Definitions

  • the present invention relates to glow plugs having two spirals for diesel engines of motor vehicles.
  • the invention relates to glow plugs including an hollow metal body, a current feeder and a tubular metal sheath which is secured to said body and is closed at the tip, in which sheath a portion of the current feeder and two series connected electrical spirals, one for heating and the other one for controlling the supply current, are inserted and embedded in an insulating powder, wherein from 50 to 70% of the lenght of the cotrol spiral is inserted into the sheath zone surrounded by said body.
  • the heating spiral performs the function of bringing the sheath to glow for sufficiently heating the combustion chamber or precombustion chamber, into which the sheath projects in order to facilitate the starting of the engine at low temperatures.
  • control spiral performs the function of limiting the intensity of current that flows into the two spirals when the temperature increases in order to avoid the sheath overheating and therefore the burnout of one or both spirals.
  • the control spiral comprises a filament having a very high positive temperature coef- .ficient of resistence with respect to that of the heating spiral, whereby, on starting the cold engine, the control spiral, that is at ambient temperature, has a low electric resistance for allowing the passage of a strong current into the heating spiral and thus a quick temperature increase of the sheath; alterwards, owing to the temperature increase of the said control spiral, this increase being caused substantially by the thermal influence of the heating spiral, an increase of its electical resistance occurs and therefore a reduction of the supply current, resulting in control of the maximum . sheath temperature that is kept within suitable limits.
  • Known double spiral glow plugs show heating curves usually situated between two limit curves: the superior one, tending, in steady state, to a maximum temperature usually amounting to about 1100°C and, the other lower curve, tending, in steady state, usually to about 1000°C.
  • the heating curves are very near to the lower limit curve, it can happen that the starting of the engine can be irregular or prevented when the ambient temperatures are below 0°C and this occurs because the sheath reaches the necessary temperature for the ignition of the air/gas oil mixture only after a prehating time higher that the nominal foreseen time.
  • the main object of the present invention is that of reducting the tolerance range of heating curves of the sheath of dual spiral glow plugs of the above mentioned tipe with the aim of getting a better control of maximum steady temperature and so reducing the preheating times of the engine, when the ambien temperature is near or under 0°C.
  • Another object of the present invention is to manufacture the double spiral by an automatized process for reducing the production costs of glow plugs.
  • a glow plug which, according to the invention, is characterized in that the two spirals are connected to each another by means of an electrically conductive spacer element having a low thermal conductivity, and in that the lenght of such spacer element is comprised betheen 8 and 18 mm, the ratio betheen the lenght of the control spiral and the lenght of the heating spiral being higher than 3 and the projection of the sheath from the body having a lenght comprised betheen 20 and 30 mm.
  • the thermal influence of the heating spiral on the control spiral is reduced to a minimum value, as, on the one hand, the two spirals are thermally separated by means of said spacer element and, on the other hand, the control i spiral is kept in thermal equilibrium with the external temperature thanks to the heat transmission that occurs through the plug body, so that the control spiral temperature is finally the temperature caused almost exclusively by the current flowing in the spirals.
  • the heating curves of glow plugs according to the invention are situated in a very reduced range that is kept near and under the conventional superior limit curve and, in steady state, the temperature tolerance is reduced by about 50% of the temoerature tolerance of the heatino curves of known glow pluqs.
  • connection of the two spirals is obtained by means of an intermediate element
  • the manufacturing of the double spiral can be carried out advanta- geusly by simple automatic systems, so avoiding the costly Laser or plasma welding processes that were required until to-day for the direct connection of the two ends of spirals.
  • the glow plug comprises an hollow metal body 1, a current feeder 2 and a tubular metal sheath 3, which, at one end, is secured to the interior of body 1 and, at the other end protrudes from the body and is closed at its tip.
  • the sheath portion of lenght L g protruding from the body 1 forms the glow tube that ends in the combustion chamber or precombustion chamber of a Diesel engine.
  • the first spiral has the function of heating the sheath for bringing the latter to glow and so promote the start of the engine while the second spiral has the function of controlling the supply current that flows the spirals in order to prevent the sheath reaching inadmissible high temperatures.
  • Control spiral 6 is inserted for about 2/3 of its lenght (2/3 Lc) into the sheath zone that is surrounded by the body 1. The opposite ends of the two spirals 5, 6 are connected respectively to the sheath tip and to the end of the current feeder 2.
  • the other two ends of spirals 5 and 6, that is the ones marked 5a and 6a are connected to one another by means of a spacer element 7 or 8 that is electrically conductive and has a low thermal conductivity.
  • the element 7 or 8 that is made of stainless steel (Ni - Cr alloy) and has a lenght Ld of some millimeters, gives a spacing between the two spirals and thus a substantial thermal separation of the same and, on the other hand, owing to its low termal conductivity, reducts heat transmission, whereby, it minimizes the thermal influence of the heating spiral 5 on the control spiral 6.
  • control spiral 6 is inserted for about 60 - 70% of its lenght Lc into the zone of the sheath 3 that is surrounded by the body 1, it occurs that the body transmit to outside the heat coming from the heating spiral mainly through the sheath, so minimizing further the thermal influence of the heating spiral on the control spiral.
  • lenght of the control spiral that is placed in the interior of body should be selected in relation to optimization of the thermal equilibrium of the spiral with respect to external temperature.
  • the heating curves of glow plugs vary in a range of temperature tolerance very reduced in comparison with the range of temperature of conventional glow plugs.
  • the comparison is shown in Fig.3 where the limit curves A and B define the tolerance range of known glow plugs, while the curves A and C define the tolerance range, represented in dotted lines, of glow plugs made in accordance to the invention.
  • the graph showing the superior limit curve A related to all glow plug types tends to 1100°C temperature, that is the maximum temperature the sheath must not exceed, in steady state, to avoid compromising the spirals life, while of the other two lower limit curves B and C, related, respectively, to known glow plugs and to glow plugs according to the invention, in steady condition, the first one tends to 1000°C temperature that is the minimum temperature the sheath in steady condition must reach for assuring at start the mixture ignition even at very low ambient temperatures and within acceptable preheating times and the second one to a higher temperature of 1050°C.
  • a glow plug of the type specified in the preamble having however: a spacer element 8 showing a lenght Ld comprised between 8 and 18 mm; a control spiral 6 of a lenght Lc; and a heating spiral 5 of a lenght Lr, the lenght ratio Lc/Lr being higher than 3 (i.e. Lc/Lr > 3), the sheath 3 protruding from the body 1 for a lenght Lg comprised between 20 and 30 mm.
  • the spacer element 8 which as above said, has a low thermal conductivity, by obstructing the heat transmission from the heating spiral towards the control spiral, causes, accordingly, a heat concentration at the sheath end.
  • the hottest part of the sheath is located at a distance of from to 1 to 1,5 mm from the end of the sheath, differently from what occurs in known two spirals glow plugs in which the hottest part is located at a distance of about 3 mm from the end.
  • the heat concentration at the sheath end has the advantage of positionning the more incandescent part of the sheath close to the axis of the fuel (gas oil) jet and therefore of causing a quicker ignition of air/gas oil mixture.
  • the graph of Fig. 3 shows the reduction of preheating times: in fact the curve C reaches the tempe-- rature of 1000°C in a time lower than 30 sec and the temperature of 850°C in 6-7 sec instead of respectively 30 sec and 6-8 sec that are the times required for reaching the same temperatures with an heating according to the curve B.
  • the Fig. 4 shows the behaviour of the temperature Tc required of the sheath for causing ignition. of the mixture when the ambient temperature Ta changes.
  • the heating temperature Tc increases passing, for example, from an heating temperature of about 800°C at an ambient temperature of +10°C, to a heating temperature of about 1100°C at an ambient temperature of -20°C. Therefore, the lower the ambient temperatures, the higher the preheating times, namely the times required for raising the sheath temperature to the necessary value for causing the mixture ignition.
  • the Fig. 1 shows a spacer element consisting of a shaped pin 7, while the Fig. 2 shows this element consisting of a tubular or drilled element 8.
  • the connection of the ends 5a and 6a of spirals 5 and 6 with the spacer element 7 is made by means of normal electric resistance welding while the connection of these ends 5a and 6a with the element 8 is made by calking.
  • any other electric or mechanical anchoring system can be used according to practical hoc responsibilities.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Resistance Heating (AREA)
EP19870100292 1986-01-16 1987-01-12 Glühkerze mit zwei Glühwendeln für Dieselmotoren Expired EP0240650B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
IT1909986 1986-01-16
IT19099/86A IT1204761B (it) 1986-01-16 1986-01-16 Candela ad incandescenza a due spirali per motori diesel di autoveicoli
IT849286 1986-09-29
IT849286 1986-09-29

Publications (2)

Publication Number Publication Date
EP0240650A1 true EP0240650A1 (de) 1987-10-14
EP0240650B1 EP0240650B1 (de) 1991-04-03

Family

ID=26326072

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870100292 Expired EP0240650B1 (de) 1986-01-16 1987-01-12 Glühkerze mit zwei Glühwendeln für Dieselmotoren

Country Status (2)

Country Link
EP (1) EP0240650B1 (de)
DE (1) DE3768994D1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0336625A3 (de) * 1988-04-06 1990-03-21 Champion Spark Plug Europe S.A. Glühkerze für Brennkraftmaschine
EP0602745A1 (de) * 1992-12-18 1994-06-22 B 80 S.r.l. Glühkerze mit zwei Regelwendeln für Dieselmotoren
US20130087114A1 (en) * 2010-05-18 2013-04-11 Sascha Joos Method and device for reducing the temperature tolerance of sheathed-element glow plugs

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0098035A2 (de) * 1982-06-28 1984-01-11 General Motors Corporation Elektrische selbstaufheizende Schnellglühstiftkerze
DE3421950A1 (de) * 1983-06-13 1984-12-13 Ngk Spark Plug Co., Ltd., Nagoya, Aichi Selbstregelnde gluehkerze
US4549071A (en) * 1981-04-30 1985-10-22 Jidosha Kiki Co., Ltd. Glow plug for use in diesel engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4549071A (en) * 1981-04-30 1985-10-22 Jidosha Kiki Co., Ltd. Glow plug for use in diesel engine
EP0098035A2 (de) * 1982-06-28 1984-01-11 General Motors Corporation Elektrische selbstaufheizende Schnellglühstiftkerze
DE3421950A1 (de) * 1983-06-13 1984-12-13 Ngk Spark Plug Co., Ltd., Nagoya, Aichi Selbstregelnde gluehkerze

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 157 (M-150), 18th August 1982, page 67 M 150; & JP-A-57 73 326 (NIPPON TOKUSHU TOGYO K.K.) 08-05-1982 *
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 89 (M-132), 27th May 1982, page 124 M 132; & JP-A-57 26 326 (NIPPON TOKUSHU TOGYO K.K.) 12-02-1982 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0336625A3 (de) * 1988-04-06 1990-03-21 Champion Spark Plug Europe S.A. Glühkerze für Brennkraftmaschine
AU608146B2 (en) * 1988-04-06 1991-03-21 Champion Spark Plug Europe S.A. Glow plug for internal combustion engine
EP0602745A1 (de) * 1992-12-18 1994-06-22 B 80 S.r.l. Glühkerze mit zwei Regelwendeln für Dieselmotoren
US20130087114A1 (en) * 2010-05-18 2013-04-11 Sascha Joos Method and device for reducing the temperature tolerance of sheathed-element glow plugs

Also Published As

Publication number Publication date
EP0240650B1 (de) 1991-04-03
DE3768994D1 (de) 1991-05-08

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