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
• • 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
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
  • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
  • F02P19/028—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs the glow plug being combined with or used as a sensor
• • 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
  • F23Q2007/002—Glowing plugs for internal-combustion engines with sensing means

Definitions

• Glow plug including a pressure sensor and engine so equipped
• the present invention relates to a glow plug comprising a pressure sensor for measuring the pressure of an engine cylinder in which the plug is housed.
• a glow plug comprising a pressure sensor adapted to measure the internal pressure of an engine cylinder in which the plug is housed, a body adapted to be fixed to the engine and a finger in which is housed a preheating electrode.
• the senor is arranged between, on the one hand, the body on which it is supported and, on the other hand, a nut secured to the upper end of a core which transmits electrical energy to the preheating electrode and which extends the finger in the body and beyond by crossing the sensor.
• the pressure inside the cylinder is felt by the finger of the spark plug and the pressure variations undergone by the finger are transmitted to the sensor via the core which is attached to it. In such a spark plug, contrary to what is shown in FIG.
• the pressure sensor is usually housed inside the body of the spark plug and bears on a shoulder produced in this tubular body. In this way, the sensor is then protected from external aggressions.
• the outer surface of the body, at the level of the pressure sensor, has a cylindrical shape with a hexagonal cross section. This part of the body is then used to screw the spark plug into the engine. The part of the spark plug then remaining outside the engine is generally called the spark plug head.
• the dimensions of the spark plug head are determined in relation to the space available in the engine close to it. Most often, this space is limited. As a result, the size of the pressure sensor is also limited.
• the object of the present invention is therefore to produce a candle comprising a pressure sensor in which the latter can have as large a bearing surface as possible according to the size of the head of the spark plug.
• a glow plug comprising a tubular body inside which is mounted a pressure sensor intended in particular to measure the internal pressure of a cylinder of an engine in which the spark plug is housed, the pressure being provided with connecting lugs extending substantially longitudinally relative to the axis of the tubular body.
• the body has in its inner side wall a longitudinal groove in which comes to take place at least one connection tab.
• the housing in which the pressure sensor takes place can be entirely used for the sensor itself without having to leave room for the means allowing the electrical connection of this sensor. It is thus possible to optimize the size of the sensor taking place in the spark plug.
• the groove is advantageously through, thus producing a longitudinal slot in the tubular body.
• the slot preferably opens out entirely in a section of the external surface of the body so as not to excessively weaken this one.
• the width of the slot corresponds to the width of a section of the body.
• the sensor is for example a piezoelectric sensor comprising a piezoelectric element disposed between two contact elements.
• the connection tabs advantageously each form only one bent piece with a contact element of the sensor. This limits the size of the sensor.
• the present invention also relates to a glow plug body comprising a substantially circular cylindrical tubular part at the end of which is a hexagonal gripping zone, of cross section transverse hexagonal, characterized in that the grip zone has a longitudinal slot.
• FIG. 1 represents a sectional view of a glow plug of the prior art
• Figure 2 shows a view similar to Figure 1 of a candle according to the present invention
• Figure 3 is an exploded perspective view of the spark plug illustrated in Figure 2
• Figure 4 is a perspective view of the spark plug illustrated in Figures 2 and 3.
• a glow plug 1 here for internal combustion engine 2 (typically a Diesel type having a cylinder head 2a) comprises a body 10, a finger 20, a core 40 and a pressure sensor 90.
• the body 10 is adapted to be fixed to the engine 2, for example by screwing to the cylinder head 2a .
• the finger 20, inside which is housed a glow plug preheating electrode 1, is disposed in the body 10 and is crimped thereto.
• the core 40 transmits electrical energy to the electrode located in the finger 20 and, therefore, is in contact with this electrode and is secured to the finger 20 which it extends inside the body 10, and to the beyond (its free end allowing its electrical connection to an electrical supply conductor protrudes from the body 10).
• the pressure sensor 90 is adapted to measure the internal pressure of (one of) the cylinder (s) of the engine.
• the sensor 90 comprises a piezoelectric element 74 which is disposed between two contact elements 72,76 made of electrically conductive material, and which is electrically insulated of the rest of the spark plug 1, in this case by two electrically insulating elements 70,78.
• the elements 72, 76 each comprise a bent side tab of electrical connection 72a, 76a directed towards the free end of the core 40 and extending essentially parallel to the longitudinal axis 1a of the spark plug (cf. FIGS. 3 and 4 ).
• the sensor 90 is secured to the body 10 by its upper surface and bears against the finger 20, so that the pressure exerted on the finger 20 compresses it against the body 10. It is perfectly understood that any compression of the finger 20 results directly in compression of the sensor 90 against the body 10. Thus, the sensor 90 no longer needs to be prestressed to measure the pressures prevailing in the engine. As can be seen in Figure 2, the core 40 passes through the sensor 90 but is not in contact with the latter. As a result, the vibrations of the core 40 are not transmitted to the sensor 90. Thus the core 40 essentially has only the function of transmitting the electric current to the preheating electrode of the finger 20, as in candles preheating without pressure sensor.
• the senor 90 is supported on a spacer 80 which rests on the finger 20 and which is disposed in the body 10, without contact with the latter. Obviously, the spacer 80 which surrounds the core 40 is not in contact with the latter. This spacer 80 allows, without changing the dimensions of the finger 20 and of the body 10, to accommodate the sensor 90 at the upper part of the spark plug 1, and not in the body 10 at the location of the upper end of the finger 20 which would generate additional constraints (obligation to use sensors of very small external diameter having lower sensitivities and exposure to higher temperatures generated by finger 20). As can be seen in FIG. 2, the sensor 90 is placed in a cavity 100 formed at the upper end of the body 10, called the head of the body 10.
• This part of the body 10 remains outside the engine when the spark plug climbed into it.
• the part of this spark plug of larger outside diameter which remains outside the engine is also called the spark plug head.
• the upper end of the spacer 80 projects beyond the bottom wall of the cavity 100 so that the sensor 90 does not rest on the body 10.
• the location of the sensor 90 in the body 10 makes it easy to produce a plastic overmolding of the upper part of the spark plug 1, the overmolding making it possible to seal and perfect the electrical connection of electrical wires to the connectors. of the sensor 90.
• the spacer 80 is made of a material giving it good rigidity (given the dimensional constraints imposed by the internal diameter of the body 10, the external diameter of the core 40 and the respective lengths of the body 10 and finger 20), and allowing it to have its own vibration mode (clearly) beyond the bandwidth of the sensor 90 (thus, the spacer 80 is not itself subjected to vibrations which can interfere with measurements made by the sensor 90).
• the spacer 80 is made of ceramic, this material having the various desired properties (insulation, rigidity, vibrations beyond the bandwidth and good mechanical strength at high temperatures).
• a support piece 60 is interposed between the sensor 90 and the spacer 80 in order to distribute the pressure coming from the spacer 80 over the entire surface of the sensor 90.
• the spark plug 1 also includes a nut 50 disposed on the sensor 10, and whose screwing to the body 10 causes the sensor 90 to be compressed against the finger 20 (by means of the spacer 80 and the support piece 60) and its attachment to the body 10
• the nut 50 which is integral with the body 10 and which, of course, is not in contact with the core 40 makes it possible to notably dampen the vibrations of the electrical connectors of the sensor 90, by compressing this sensor.
• the thread of the nut 50 is produced at its external periphery and cooperates with a thread produced on the internal face of the side walls 110 of the cavity 100.
• the head of the body 10 has an external surface to hexagon. This head is thus cylindrical in shape with a hexagonal cross section.
• a slot 120 is made in a side wall 110.
• This slot 120 is of a width corresponding to the wall in which it is made , so that this wall disappears.
• the head of the body 10 then in fact only has five side walls 110.
• the lateral tabs for electrical connection 72a, 76a can be housed in the slot 120 of the head of the body 10 without removing space from the pressure sensor 90 inside this head. Indeed, without this slot 120, it is advisable to reserve in the cavity 100 a space for the passage at least of the lateral tab of electrical connection 72a which corresponds to the contact element 72 located most inside the Glow plug.
• the production of the candle 1 according to the present embodiment is particularly simple: it consists of a stack of parts; no severe prestressing of the sensor 90 is necessary, it suffices to compress it slightly to immobilize it.
• the core is no longer used to transmit the pressure variations to the sensor, it is possible to reduce its diameter and therefore to use a sensor 90 having relatively small internal and external diameters (for example an internal diameter 2.6 millimeters and an outer diameter of 8.5 millimeters).
• This spark plug 1 can also accommodate a sensor 90 which occupies the entire cavity 100 provided for this purpose in the spark plug head thanks to the presence of the slot 120. This is favorable for the sensitivity of the sensor 90.
• the tightening torques usually used for screw a glow plug are such that the presence of the slot 120, even when it corresponds to the entire width of a pan of a hexagon head, does not affect the strength of the body 10 and there there is no risk of deforming the head of the body during a screwing or unscrewing. Obviously, it is possible to make modifications to the present embodiment.
• a slot in the head of the candle, or of the body of the candle without providing for securing the sensor to the body of the candle by its upper face and making it bear against the finger so that the pressure exerted on the finger compresses the sensor against the spark plug body.
• a slot with any glow plug structure incorporating in its head a pressure sensor.
• This slot can for example be envisaged with a pressure sensor mounted as is that of the figure 1.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Measuring Fluid Pressure (AREA)
• Spark Plugs (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=34429733

Family Applications (2)

Family Applications Before (1)

Country Status (7)

Families Citing this family (15)

Family Cites Families (14)

• 2003
  • 2003-10-29 FR FR0312682A patent/FR2861836B1/fr not_active Expired - Fee Related
• 2004
  • 2004-10-25 US US10/577,150 patent/US7759612B2/en not_active Expired - Fee Related
  • 2004-10-25 JP JP2006537153A patent/JP2007533943A/ja not_active Withdrawn
  • 2004-10-25 EP EP04790815A patent/EP1687569A1/de not_active Withdrawn
  • 2004-10-25 CN CNB2004800319187A patent/CN100498075C/zh not_active Expired - Fee Related
  • 2004-10-25 KR KR1020067010521A patent/KR20060105762A/ko not_active Application Discontinuation
  • 2004-10-25 WO PCT/EP2004/012026 patent/WO2005040681A1/fr active Application Filing
  • 2004-10-28 EP EP04805337A patent/EP1690041A1/de not_active Withdrawn
  • 2004-10-28 CN CNA2004800319134A patent/CN1902442A/zh active Pending
  • 2004-10-28 WO PCT/FR2004/002783 patent/WO2005043039A1/fr active Application Filing
  • 2004-10-28 US US10/577,151 patent/US20070062267A1/en not_active Abandoned
  • 2004-10-28 JP JP2006537361A patent/JP2007510123A/ja not_active Withdrawn

Non-Patent Citations (1)

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