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
• • 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
  • 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

• the present invention relates to a glow plug head fitted with a pressure sensor.
• an internal combustion engine in particular an engine of the type
• Diesel it is known to mount a glow plug on each cylinder.
• This glow plug is generally screwed into a cylinder head. It usually comprises a tubular body having on its outer surface a threaded portion allowing its fixing in a corresponding bore made in the cylinder head. Once this body is mounted in its bore, part of it is inside the combustion chamber and another part, called the head of the spark plug, is outside of it.
• the part inside the combustion chamber has a finger inside which there is a heating electrode.
• This electrode is supplied by a core which passes through the tubular body of the spark plug and is itself supplied with electrical energy from a connector generally located in the spark plug head.
• a pressure sensor can take place in the head of such a glow plug.
• This sensor is intended to measure the pressure inside the corresponding combustion chamber. Knowing this pressure allows better regulation of the engine by optimizing its efficiency and reducing its consumption. Thanks to this sensor, it is also possible to have a less polluting engine.
• a pressure sensor is housed in the glow plug head, in addition to the connector supplying electrical energy to the core of the glow plug, means that a large plug head must be provided. This first increases the cost of this candle and then increases the mass of the head of the candle. Indeed, the sensor body is fully machined. The maximum diameter of this body is located at the level of the head, at the place provided with a grip zone, generally hexagonal, used for the screwing / unscrewing of the glow plug.
• the present invention aims to provide a glow plug equipped with a pressure sensor whose cost is limited.
• the head of this candle will have a low mass and will not disturb the pressure measurement made by the sensor located inside of it.
• the invention provides a glow plug comprising a plug body, a pressure sensor disposed inside the plug body, a threaded zone on the outside of the plug body as well as gripping means, generally cylindrical in shape with a hexagonal section, allowing the body to be gripped and screwed into a corresponding thread.
• the gripping means are made of synthetic material.
• the part of the body intended to hold the various components of the glow plug and to allow them to be mounted in a tapped bore may have a smaller diameter.
• the body of a glow plug incorporates a part of hexagonal section to facilitate the screwing of the plug and is entirely machined from a circular cylindrical metal bar.
• the diameter of the bar used is determined by the diameter of the section of the grip zone.
• the solution proposed by the invention makes it possible to limit the diameter of the bar of raw material used to produce the body (generally made of steel) of the glow plug and thus the cost price of this body, especially limiting the cost of the operations of 'machining.
• the synthetic material used can be a polyamide such as, for example, PA 6.6 or PA 6.12.
• the gripping means produce an overmolding of the pressure sensor and of the spark plug body. In this way, these gripping means made of synthetic material effectively protect the pressure sensor against any external attack.
• a glow plug according to the invention may further comprise a heating electrode, connection means on the one hand for the supply of electrical energy to the heating electrode and on the other hand for transmit the signal from the pressure sensor.
• connection means are advantageously overmolded to be protected.
• a first alternative embodiment of such a glow plug may provide that the connection means form a male connector forming only one piece with the gripping means while another alternative may provide that the connection means are connected to electrical wires, and that these wires protrude from the overmolded part of the spark plug body.
• the plug body has, for example on the side of the gripping gripping means on at least part of its periphery. If the body is a tubular body, then the grooves are for example oriented longitudinally so as to best transmit a torque of screwing (or unscrewing).
• the present invention also relates to an internal combustion engine which comprises at least one glow plug as described above.
• FIG. 1 represents in perspective a glow plug according to the invention as well as a female connector
• FIG. 2 shows from another angle and on an enlarged scale the glow plug of FIG. 1
• FIG. 3 shows in side view another glow plug according to the invention
• FIG. 4 shows the candle of FIG. 3 in longitudinal section
• Figure 5 shows in perspective a third embodiment of a glow plug according to the invention.
• all the glow plugs shown in the drawing comprise a body 2 and a finger 4.
• the body 2 is a generally circular cylindrical tubular part.
• the glow plug can be fixed in a cylinder head of an internal combustion engine, in particular a diesel type engine.
• the body 2 carries the finger 4.
• the finger 4 When the candle is mounted on a cylinder head, the finger 4 is inside a combustion chamber. Inside this finger, there is, in known manner, a heating electrode (not shown) supplied with electrical energy by a core 8 (FIG. 4) passing through the tubular body 2.
• the glow plug On the side opposite finger 4, the glow plug carries a pressure sensor 10 to measure the pressure prevailing in the corresponding combustion chamber.
• This pressure sensor 10 is generally a piezoelectric sensor.
• the head of the glow plug that is to say the part of this candle located opposite the finger 4, is made of synthetic material. It is presented, seen from the outside, in two parts: a first part forming a grip zone 12 and a second part forming a male connector 14.
• the synthetic material used for the production of the candle head can be a polyamide such as, for example, PA 6.6 or PA 6.12.
• the grip zone 12 is in the extension of the body 2, is coaxial with respect to this body 2 and has a hexagonal cross section. This gripping zone 12 is integral with the body 2. It is for example molded onto this body 2. This gripping zone 12 is used for screwing and unscrewing the glow plug.
• the tightening torques of such a spark plug are compatible with the production of the grip zone 12 in synthetic material.
• the connector 14 forming the second part of the head of the glow plug allows the electrical connection of the glow plug to the outside. This connection makes it possible on the one hand to supply electrical energy to the heating electrode of finger 4 and on the other hand to transmit the signal measured by the piezoelectric pressure sensor 10.
• This connector thus has three contacts: a first contact 16 connected to the core 8 of the spark plug (the return is by ground) and two other contacts 18 each connected to a collector of the piezoelectric pressure sensor 10 (cf. figure 2).
• This male connector 14 is intended to receive a female connector 20 corresponding. This is for example, as shown in Figure 1, provided with a fixing system 22 with bayonet.
• the corresponding male connector 14 then comprises on its outer surface a lug 24 cooperating with the fixing system 22 of the female connector 20. From this female connector 20, two electric wires leave, one corresponding to the power supply of the heating electrode of finger 2 and the other corresponding to the transmission of the signal from the pressure sensor 10.
• the pressure sensor 10 is located in the head of the glow plug and is molded by the synthetic material forming the grip zone 12 and the connector 14.
• FIGS. 3 and 4 show an alternative embodiment of a glow plug. preheating according to the invention.
• the head of the glow plug is also produced by overmolding the end of the body 2 with synthetic material. We find in this glow plug head the pressure sensor 10 as well as means for connecting this sensor and the core 8.
• the glow plug head On its outer face, the glow plug head also has a gripping area 12.
• the difference with the glow plug of Figures 1 and 2 is that here the male and female connectors are grouped in a single piece. Electric wires are then directly fixed, for example by welding, on contacts of the pressure sensor 10 and / or on the core 8.
• the pressure sensor 10, the means of connection of this sensor 10 and of the core 8 as well as the upper part of the body 2 are then overmolded with synthetic material to form a one-piece head 26.
• the outer surface of this one-piece head 26 has over at least part of its height a hexagonal cross section.
• the body 2 carries a tubular intermediate piece 28 on which is mounted the finger 4.
• the purpose of this tubular intermediate piece 28 is to isolate the finger 4 from the body 2.
• the finger 4 is adjusted with clamping at the lower end of the tubular intermediate piece 28.
• the latter is also fixed by adjustment with clamping at the lower end of the body 2.
• the tubular intermediate piece 28 crosses the entire body 2.
• On the side of the head the glow plug, this tubular intermediate piece 28 has a flare in which is housed the pressure sensor 10.
• the pressure of the gases in the combustion chamber exerts forces on the finger 4. These forces are transmitted to the sensor via a spacer 30, made for example of ceramic material.
• a spacer 30, made for example of ceramic material As can be seen in FIG.
• FIG. 4 shows an alternative embodiment of a glow plug according to the invention allowing, by other means than those described above with reference to Figure 4, excellent retention of the part made of synthetic material.
• a one-piece head 26 'from which protrude two electrical wires has in its upper part (that is to say on the side of the head of the glow plug) a zone having, at its outer periphery, longitudinal ridges 32.
• the diameter of the body 2 is substantially less than the outside diameter of the head of the glow plug.
• the fact of having produced the grip zone allowing the screwing and unscrewing of the glow plug in a corresponding threaded bore in synthetic material makes it possible to significantly reduce the diameter of the bar of raw material used for the production of the body of this candle .
• the use of synthetic material at the head of the glow plug makes it possible to obtain other important advantages.
• the use of synthetic material makes it possible to reduce the mass of the head of the glow plug. Indeed, the density of the synthetic material is lower compared to that of the steel usually used to make this head.
• This reduction in mass is favorable to a better measurement of the pressure by the pressure sensor located inside this head.
• the head of the glow plug is subjected to vibrations during the operation of the engine in which it is mounted. These vibrations can cause noise in the signal recorded by the pressure sensor.
• the natural frequency of the spark plug head vibrations is moved away from the bandwidth of the pressure sensor.
• the vibrations of the head of the glow plug transmitted to the sensor then do not disturb the measurements made by the latter.
• the overmolding of the sensor and the connection means also makes it possible to ensure an excellent seal at the level of this sensor and of these connections. Overmolding thus allows protection of the sensor which increases its reliability and its lifespan.
• the present invention is not limited to the embodiments described above by way of nonlimiting examples. It also relates to all the variant embodiments within the reach of those skilled in the art.

Landscapes

• 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)
• Ignition Installations For Internal Combustion Engines (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34945456

Family Applications (1)

Country Status (7)

Families Citing this family (4)

Citations (5)

Family Cites Families (16)

• 2004
  • 2004-04-27 FR FR0404465A patent/FR2869392B1/fr not_active Expired - Fee Related
• 2005
  • 2005-04-19 WO PCT/FR2005/000933 patent/WO2005111502A1/fr not_active Ceased
  • 2005-04-19 US US11/587,653 patent/US7775187B2/en not_active Expired - Fee Related
  • 2005-04-19 KR KR1020067024849A patent/KR101219584B1/ko not_active Expired - Fee Related
  • 2005-04-19 CN CN2005800131365A patent/CN1977129B/zh not_active Expired - Fee Related
  • 2005-04-19 EP EP05757947A patent/EP1747405A1/fr not_active Withdrawn
  • 2005-04-19 JP JP2007510067A patent/JP4852036B2/ja not_active Expired - Fee Related

Patent Citations (5)

Non-Patent Citations (3)

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