JP2009236438A - Glow plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glow plug capable of reducing power consumption compared to conventional ones. <P>SOLUTION: A heater support member 10 for supporting a heater 20 in a housing 1 is provided with a housing connection part 12 composed of a flange collar-likely projecting outward. A heat insulating material layer 50 is provided to intervene between the housing connection part 12 and a tip side housing 2 and between the housing connection part 12 and a rear-end side housing 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glow plug used in an internal combustion engine such as an automobile engine.

Conventionally, glow plugs have been used to promote startup of internal combustion engines such as automobile diesel engines. As such a glow plug, the front end side protrudes from the front end portion of the housing and the rear end side is accommodated in the housing in a cylindrical housing provided with a screw portion for engine attachment on the outer peripheral surface. The thing of the structure which supported the heater with the heater support member is known. In addition, an insulating layer is provided between the outside of the lead shaft member that supplies power to the heater and the inner peripheral surface of the housing, so that the lead shaft member can be firmly fixed in the housing while maintaining insulation. Plugs are also known (see, for example, Patent Document 1).
JP 2004-132688 A

  In the conventional glow plug described above, the heat generated by the heater escapes to the outside through the heater support member and the housing. For this reason, the electric power required in order to heat a heater to desired temperature increased, and there existed a subject that power consumption was large.

  The present invention has been made to solve the above problems. An object of this invention is to provide the glow plug which can aim at reduction of power consumption compared with the past.

  The glow plug of the present invention is a housing that is formed in a cylindrical shape, has a seat surface that is in close contact with the engine on the front end side in the axial direction, and has a screw portion for engine mounting on the outer peripheral surface on the rear end side in the axial direction from the seat surface. A glow plug including a heater provided such that a front end protrudes from a front end portion of the housing and a rear end side is accommodated in the housing, and a heater support member that supports the heater with respect to the housing. In addition, a heat insulating material layer is interposed at a joint interface between the housing and the heater support member.

  In the glow plug of the present invention having the above-described configuration, the heat insulating material layer is interposed at the joint interface between the housing and the heater support member that supports the heater with respect to the housing. As a result, the heat of the heater can be prevented from being transferred to the housing via the heater support member, and the power required to heat the heater to a desired temperature can be reduced, thereby reducing the power consumption. Can be planned. In addition, a heat insulating material layer means the layer which consists of material with lower heat conductivity than the member in which the said heat insulating material layer was provided.

  Further, the glow plug of the present invention is formed in a cylindrical shape, has a seat surface in close contact with the engine on the axial front end side, and has a screw portion for engine attachment on the outer peripheral surface on the axial rear end side from the seat surface. A housing having a front end protruding from a front end of the housing and a rear end being accommodated in the housing, and a heater support member for supporting the heater with respect to the housing, A glow plug comprising a heater support member having a cylindrical sleeve positioned on the outer peripheral side of the heater, wherein at least one of the inner surface of the housing and the outer surface of the sleeve and the inner surface of the sleeve and the outer surface of the heater One of them is characterized by interposing a heat insulating material layer.

  In the glow plug of the present invention configured as described above, the heater support member that supports the heater with respect to the housing has a cylindrical sleeve positioned on the outer peripheral side of the heater, and between the inner surface of the housing and the outer surface of the sleeve, A heat insulating material layer is interposed between at least one of the inner surface of the sleeve and the outer surface of the heater. As a result, it is possible to suppress the heat of the heater from being transmitted to the housing through the heater support member by radiation, reducing the power required to heat the heater to a desired temperature, and reducing power consumption. Can be planned.

  In the above glow plug, when the pressure sensor element and the insulating member that supports the pressure sensor element are provided on the rear end side of the heater, the glow plug is interposed between the pressure sensor element and the heater. As described above, it is preferable that a heat insulating material layer is formed on the insulating member. By configuring in this way, it is possible to prevent heat from being transmitted to the rear end side of the heater and escape, and to reduce power consumption required to heat the heater to a desired temperature. Can be achieved. Moreover, it can suppress that the bad influence by heat reaches a pressure sensor element.

  Further, in the above glow plug, if a heat insulating material layer is formed on at least the outer surface of the screw portion for mounting the engine of the housing, heat is transferred from the screw portion to the internal combustion engine to escape. Can be suppressed. Further, in the glow plug described above, if a heat insulating material layer is formed on the seat surface of the housing, it is possible to suppress escape of heat transmitted from the seat surface to the internal combustion engine. Thereby, the electric power required in order to heat a heater to desired temperature can be reduced, and reduction of power consumption can be aimed at.

  According to the glow plug of the present invention, it is possible to provide a glow plug capable of reducing power consumption compared with the conventional one.

  Embodiments in which the present invention is applied to a glow plug with a combustion pressure sensor will be described below with reference to the drawings. 1 and 2 show a configuration of a glow plug 100 with a combustion pressure sensor according to an embodiment of the present invention. FIG. 1 is an enlarged cross-sectional view showing a tip portion of the glow plug 100 with a combustion pressure sensor. FIG. 2 is a partially cutaway side view showing the overall configuration of a glow plug 100 with a combustion pressure sensor.

  As shown in FIGS. 1 and 2, the glow plug 100 with a combustion pressure sensor is made of a high-strength metal such as carbon steel (S45C, etc.), stainless steel (eg, SUS430, SUS630, etc.), and has a substantially cylindrical shape. A formed housing 1 is provided. The housing 1 is configured by connecting a front end side housing 2 and a rear end side housing 3.

  As shown in FIG. 2, a screw portion 4 for attaching the glow plug 100 with a combustion pressure sensor to an engine (engine) (not shown) is formed on the outer peripheral surface of the rear end side housing 3. In the present embodiment, the heat insulating material layer 50 is formed on the outer periphery of the screw portion 4 by coating. Further, a tool engaging portion 5 for engaging a tool such as a spanner or a wrench when the housing 1 is attached to the engine is provided on the outer peripheral portion on the rear end side from the screw portion 4.

  As shown in FIG. 1, the front end side housing 2 has an opening 6 for causing the heater 20 to protrude from the front end of the housing 1, and the end surface on the front end side in the axial direction is an automobile diesel engine. A sheet surface (tapered surface) 7 that is in close contact with the engine is formed. In this embodiment, the heat insulating material layer 50 is formed on the sheet surface 7 by coating. A heater support member 10 made of a metal such as stainless steel (for example, SUS430, SUS630) is provided in the opening 6. The heater support member 10 includes a sleeve 11 that is formed in a substantially cylindrical shape and is located outside the heater 20. The sleeve 11 has a housing connection that includes a flange that protrudes outwardly from the outer periphery of the sleeve 11. A portion 12 is provided. The heater support member 10 is connected to the housing 1 by fixing the housing connecting portion 12 by welding or the like in a state of being interposed between the front end side housing 2 and the rear end side housing 3. Further, a heat insulating material layer 50 is provided between the housing connection portion 12 and the front end side housing 2 and between the housing connection portion 12 and the rear end side housing 3. The heat insulating material layer 50 is provided by sandwiching a coating or a resin thin film. When welding is performed with the heat insulating material layer 50 interposed therebetween, a part of the heat insulating material layer 50 is melted by welding and becomes conductive.

  In addition, the heater support member 10 is provided with a movable portion 13 so that the entire heater support member 10 is located on the front end side of the seat surface 7, that is, the entire portion is exposed on the front end side of the housing 1 (see FIG. 1 is a region indicated by a symbol “S”.) The movable portion 13 has a function of displacing the heater 20 in the axial direction by elastically deforming according to the combustion pressure applied to the pressure receiving surface of the heater 20. In the present embodiment, the movable portion 13 is configured by a thin portion whose thickness is thinner than the thickness of the other heater support member 10.

  A heater holding portion 14 is provided on the distal end side of the movable portion 13 of the heater support member 10. The heater holding portion 14 is in a state in which the heater 20 is held on its inner peripheral surface by press-fitting or brazing, and the thickness thereof is larger than that of the movable portion 13.

  The heater 20 is, for example, a ceramic heater (made of silicon nitride, alumina, or the like) in which a conductive ceramic 22 is provided inside an insulating ceramic 21. The tip surface 23 of the heater 20 shown in FIG. 2 is a pressure receiving surface that receives the combustion pressure in the combustion chamber. The heater 20 is not limited to a ceramic heater, and may be a metal heater (made of a coil, a stainless tube, insulating powder, etc.) constituting a metal glow plug.

  The sleeve 11 on the rear end side of the housing connection portion 12 of the heater support member 10 extends in a cylindrical shape toward the rear end side. An annular element presser 31 is fixed to the rear end portion. The element presser 31 has a surface whose tip end is perpendicular to the axis, and is made of a high-strength metal such as carbon steel (S45C or the like) or stainless steel (for example, SUS430 or SUS630). A pressure detection element 30 is provided inside the rear end side of the heater support member 10 on the front end side of the element presser 31. The pressure detection element 30 can be a piezoelectric element, for example. A disc-shaped insulating member 40 is disposed adjacent to the rear end side surface (corresponding to the upper surface in the figure) of the pressure detecting element 30 so that the pressure detecting element 30 is insulated from the annular element presser 31. Is in a state.

  A through hole 32 is formed in the center of the element presser 31, and a conductive central shaft (lead shaft member) 33 formed in a rod shape is provided so as to penetrate the through hole 32. . A flange portion 34 having a large diameter is formed at the front end portion of the middle shaft 33, and the flange portion 34 is disposed so as to be interposed between the pressure detection element 30 and the rear end portion of the heater 20. The combustion pressure transmitted from 20 is transmitted to the pressure detection element 30 via the flange portion 34 and the insulating member 41 provided between the flange portion 34 and the pressure detection element 30. The middle shaft 33 is electrically connected to the conductive ceramic 22 of the heater 20 through a conductive ring member 35, and power is supplied to the heater 20 through the middle shaft 33. The middle shaft 33 is electrically connected to the heater energization line 8 shown in FIG. 2, and the pressure detection element 30 is connected to a signal output line via an electronic circuit for processing an output signal from the pressure detection element 30 (not shown). 9 is electrically connected to the outside of the housing 1. The electronic circuit may be provided outside the housing 1.

  In the present embodiment, the heat insulating material layer 50 is provided by sandwiching a coating or a resin thin film on both surfaces on the front end side and the rear end side in the axial direction of the insulating members 40 and 41 described above. Further, a heat insulating material layer 50 is provided on the inner surface of the sleeve 11 by coating.

  In FIG. 1, a portion 15 adjacent to the rear end side of the housing connecting portion 12 is a press-fit portion that is thicker and larger in diameter than the other portions of the rear end side portion of the heater support member 10. When the press-fitting portion 15 is press-fitted into the rear end side housing 3 of the first rear end housing 3, the rear end side housing 3 (housing 1) and the heater support member 10 are aligned with the rear end side housing 3 so that the axis The heater support member 10 is fixed.

  In the glow plug 100 with the combustion pressure sensor configured as described above, as shown in FIG. 2, the leading end of the heater 20 is in a state of protruding from the leading end of the housing 1. The glow plug 100 is inserted into a plug mounting hole of an engine (not shown), and the screw portion 4 is fastened to the mounting screw of the engine to bring the seat surface 7 into contact with the engine, thereby ensuring airtightness. In this state, the heater 20 is attached to the internal combustion engine so that the front end side is located in the combustion chamber, and the heater 20 is energized to generate heat, thereby assisting in starting the internal combustion engine.

  When combustion pressure is applied to the front end surface (pressure receiving surface) 23 of the heater 20, the movable portion 13 is elastically deformed (bends), whereby the heater 20 is displaced in the axial direction toward the rear, and the pressure detection element. When 30 is pressed, a pressure detection signal is detected. An electronic circuit (not shown) for processing an output signal from the pressure detection element 30 is mounted in the housing 1 on the rear end side of the pressure detection element 30, and the signal of this electronic circuit is a signal. A change in combustion pressure in the engine (engine) is detected by being input to a control device such as an ECU via the output line 9.

  When the glow plug 100 with a combustion pressure sensor is used in such a state, in the present embodiment, the heat generated in the heater 20 escapes to other parts by the heat insulating material layer 50 formed in each part. Can be suppressed. In other words, the heat insulating material layer 50 provided between the housing connection portion 12 of the heater support member 10 and the front end side housing 2 suppresses heat from escaping to the front end side housing 2 through the heater support member 10 due to heat transfer. can do. Further, the heat insulating material layer 50 provided on the seat surface 7 can suppress heat from escaping from the front end side housing 2 to the internal combustion engine by heat transfer. Further, heat is transferred to the rear end side housing 3 through the heater support member 10 by heat transfer by the heat insulating material layer 50 provided between the housing connecting portion 12 of the heater support member 10 and the rear end side housing 3. Can be suppressed. Furthermore, heat can be prevented from escaping from the rear end side housing 3 to the internal combustion engine by heat transfer by the heat insulating material layer 50 provided on the outer peripheral portion of the screw portion 4.

  Further, the heat insulating material layer 50 provided on the insulating members 40 and 41 can suppress the heat generated in the heater 20 from escaping to the rear end side of the heater 20. Further, the heat insulating material layer 50 provided on the insulating member 41 also has an action of suppressing heat from being transmitted to the pressure detection element 30 and suppressing the adverse effect of heat on the pressure detection element 30.

  Furthermore, the heat generation material layer 50 provided on the inner surface of the sleeve 11 of the heater support member 10 can suppress the heat generated in the heater 20 from escaping to the heater support member 10 due to radiation. Further, the heat insulating material layer 50 provided on the inner surface of the sleeve 11 ensures electrical insulation between the sleeve 11 and the conductive ring member 35 that is electrically connected to the central shaft 33 and supplies power to the heater 20. It also has an effect | action, and it can suppress that an electrical leak generate | occur | produces between the ring member 35 and the sleeve 11 by this.

  In addition, each above-mentioned heat insulating material layer 50 consists of material with lower heat conductivity than the member which provides the said heat insulating material layer 50. FIG. These thermal material layers 50 are, for example, polyimide resin, PPS (polyphenylene sulfide) resin, PEEK (trade name) resin. It can be formed of heat-resistant paint, DLC (diamond-like carbon) or the like, and may be formed of different materials depending on the respective heat insulating material layers 50. Moreover, when forming the heat insulating material layer 50 by coating, it is preferable to perform coating at the part stage. For example, the heat insulating material layer 50 provided on the sheet surface 7 and the heat insulating material provided on the outer peripheral portion of the screw portion 4 are used. The material layer 50 may be formed by a method such as spraying a heat-resistant paint on these parts in a finished state. Further, when the heat insulating material layer 50 is formed by coating, the heat insulating material layer 50 is formed with a thickness equal to or greater than the surface roughness of the portion to be coated, and the surface is completely covered by the heat insulating material layer 50. preferable.

  In addition to the piezoelectric element, the pressure detecting element 30 may be composed of, for example, an Si element or an SOI element, and may be configured to output an electrical signal corresponding to a strain when pressure is applied. When the pressure detection element 30 is configured, a structure in which an element such as an Si element or an SOI element is bonded to a substrate made of glass, metal, or the like can be used. A piezoresistor is formed on the surface of the element, and the pressure is detected from a change in resistance value when the element is pressed.

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment and the like, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. For example, the heat insulating material layers 50 provided at a plurality of locations do not necessarily have to be provided at all locations, and if at least one location is provided among the plurality of locations described in the embodiment, the effect of reducing power consumption can be obtained. Obtainable. Further, a heat insulating material layer 50 may be provided at a site such as between the outer surface of the sleeve 11 and the inner surface of the housing 1.

The figure which shows the principal part structure of the glow plug with a combustion pressure sensor which concerns on embodiment of this invention. The figure which shows the whole structure of the glow plug with a combustion pressure sensor which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Front end side housing, 3 ... Rear end side housing, 4 ... Screw part, 5 ... Tool engaging part, 6 ... Opening part, 7 ... Seat surface, 8 ... Heater Conductive wire, 9 ... signal output wire, 10 ... heater support member, 11 ... sleeve, 12 ... housing connection part, 13 ... movable part, 14 ... heater holding part, 15 ... press-fit part, 20 ... ... Heater, 21 ... Insulating ceramic, 22 ... Conductive ceramic, 23 ... Tip surface (pressure-receiving surface), 30 ... Pressure sensing element, 31 ... Element presser, 32 ... Through hole, 33 ... Middle shaft 34 ... Flange, 35 ... Ring member, 40, 41 ... Insulating member, 50 ... Insulating material layer, 100 ... Glow plug with combustion pressure sensor.

Claims (5)

A housing that is formed in a cylindrical shape, has a seat surface in close contact with the engine on the axial front end side, and has a screw portion for engine attachment on the outer peripheral surface on the axial rear end side from the seat surface;
A heater provided such that a front end side protrudes from a front end portion of the housing and a rear end side is accommodated in the housing;
A glow plug comprising: a heater support member that supports the heater with respect to the housing;
A glow plug, wherein a heat insulating material layer is interposed at a joint interface between the housing and the heater support member. A housing that is formed in a cylindrical shape, has a seat surface in close contact with the engine on the axial front end side, and has a screw portion for engine attachment on the outer peripheral surface on the axial rear end side from the seat surface;
A heater provided such that a front end side protrudes from a front end portion of the housing and a rear end side is accommodated in the housing;
A heater support member for supporting the heater with respect to the housing, the heater support member having a cylindrical sleeve located on an outer peripheral side of the heater,
A glow plug, wherein a heat insulating material layer is interposed between at least one of the inner surface of the housing and the outer surface of the sleeve and between the inner surface of the sleeve and the outer surface of the heater. A glow plug according to claim 1 or 2,
A pressure sensor element on the rear end side of the heater, and an insulating member that supports the pressure sensor element,
A glow plug, wherein a heat insulating material layer is formed on the insulating member so as to be interposed between the pressure sensor element and the heater. The glow plug according to any one of claims 1 to 3,
A glow plug, wherein a heat insulating material layer is formed on at least an outer surface of a screw portion for mounting the engine of the housing. A glow plug according to any one of claims 1 to 4,
A glow plug, wherein a heat insulating material layer is formed on at least the sheet surface of the housing.

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