JP2019113225A - Glow plug and manufacturing method for the same - Google Patents

Abstract

To provide a glow plug which can protect a center shaft and a joint part between the center shaft and a ceramic heater, and to provide a manufacturing method for the glow plug.SOLUTION: A glow plug 1 includes: a cylindrical housing 2; a ceramic heater 3 inserted into a tip part of the housing 2; a center shaft 4 which establishes electric continuity with the ceramic heater 3; and a rotation stop member 51 which prevents rotation of the center shaft 4 relative to the housing 2. An arrangement recessed part 22 in which the rotation stop member 51 is disposed is formed at an inner periphery of a base end part of the housing 2. A center shaft engagement part 41 which engages with the rotation stop member 51 is formed by a metallic material integrated with the center shaft 4 at an outer periphery of the center shaft 4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a glow plug and a method of manufacturing the same.

  The glow plug is used in an internal combustion engine such as a diesel engine as a heating source for heating fuel injected into the combustion chamber or a mixture of fuel and air taken into the combustion chamber to cause self-ignition. The glow plug is provided with a ceramic heater that generates heat by energization. The supply of power to the ceramic heater is performed from an external power supply through an intermediate shaft inserted into the housing and connected to the proximal end side of the ceramic heater. In addition, the terminal of the external power supply is often fixed by tightening a nut against an external thread formed at the proximal end of the center shaft.

  For example, in the glow plug for a diesel engine of Patent Document 1, as a first structure, the external connection terminal conducted to the heating element (sheath type heater) through the electrode extraction fitting is detentated to the inner hole of the housing. It is described to provide an insulating fixing member to be fixed. The insulating fixing member seals the external connection terminal with respect to the housing by sealing between the inner surface of the housing and the outer surface of the external connection terminal.

  Further, in the glow plug of Patent Document 1, as the second structure, a polygonal shaped portion such as a hexagon is formed on the external connection terminal mounted on the outer periphery of the electrode fitting, and the insulation is disposed in the inner hole of the housing. It is described that the bush is formed with a recess which engages with the polygon. The engagement between the polygonal portion and the recess can prevent rotation of the external connection terminal with respect to the housing.

Japanese Patent Application Publication No. 2001-263662

  In the first structure of the glow plug of Patent Document 1, the insulating fixing member is only fixed to the inner surface of the housing and the outer surface of the external connection terminal. An engagement portion is not formed between the external connection terminal and the insulating and fixing member. Moreover, in the 2nd structure of the glow plug of patent document 1, the engaging part by a shape is formed between the external connection terminal and the insulation bush. However, in this second structure, a thin-walled portion whose thickness is significantly thinner than the other portions is present in the portion of the external connection terminal attached to the electrode extraction fitting.

  By the way, when attaching terminals, such as an external power supply, to an external connection terminal (or center axis | shaft), the nut is tightened to the external thread part of an external connection terminal. And, in order to shorten the work time of the tightening operation, a motorized or pneumatic tool may be used. In this case, when the nut is tightened, torsional stress is applied to the external connection terminal. In particular, when the nut is seated (when the nut contacts a terminal such as an external power supply and tightening is completed), a torsional impact force as a large torsional force may act on the external connection terminal. Therefore, the detent structure of the external connection terminal (or the central shaft) with respect to the housing leaves room for further improvement.

  In the first structure of the glow plug of Patent Document 1, when a torsional impact force is applied to the external connection terminal when the nut is tightened, the insulating fixing member fixed to the inner surface of the housing and the outer surface of the external connection terminal peels off. Are concerned. In this case, there is a possibility that a twisting impact force acts on an electrode fitting as a joint between the center shaft and the ceramic heater.

  On the other hand, in the second structure of the glow plug of Patent Document 1, there is a concern that the thin portion of the external connection terminal may be damaged due to insufficient strength when a twisting impact force at the time of tightening the nut acts on the external connection terminal.

  The present invention has been made in view of such problems, and has been obtained as an attempt to provide a glow plug capable of protecting a center shaft and a joint portion between the center shaft and a ceramic heater from damage, and a method of manufacturing the same.

One aspect of the present invention is a cylindrical housing (2);
A ceramic heater (3) inserted into the end of the housing;
An inner shaft (4) inserted into the base end side (L2) of the ceramic heater and electrically conducted to the ceramic heater in the housing;
And a detent member (51) disposed in a gap between the housing and the middle shaft, which insulates the housing from the middle shaft and performs rotation of the middle shaft with respect to the housing.
The inner periphery of the proximal end of the housing is provided with an arrangement recess (22) in which the locking member is arranged,
In the glow plug (1), an inner shaft engaging portion (41) engaged with the anti-rotation member is formed on the outer periphery of the inner shaft by a metal material integral with the inner shaft.

Another aspect of the present invention is a cylindrical housing (2);
A ceramic heater (3) inserted into the end of the housing;
An inner shaft (4) inserted into the base end side (L2) of the ceramic heater and electrically conducted to the ceramic heater in the housing;
A glow plug (1) comprising: a rotation stopping member (51) disposed in a gap between the housing and the middle shaft, insulating the housing from the middle shaft, and stopping the rotation of the middle shaft with respect to the housing Method,
Placing the anti-rotation member in a placement recess (22) formed on the inner periphery of the proximal end of the housing;
Inserting the middle shaft into the housing, and disposing a middle shaft engaging portion (41) formed on the outer periphery of the middle shaft by a metal material integral with the middle shaft on the inner peripheral side of the rotation preventing member , And a method of manufacturing a glow plug.

  In the glow plug according to the above aspect, attention is paid to the shape and strength of the portion where the center shaft and the detent member engage, and from the torsional impact force acting on the center shaft when tightening the nut on the center shaft, the center shaft and the center shaft We are devising to protect the joint with the ceramic heater.

  Specifically, on the outer periphery of the center shaft, a center shaft engaging portion that engages with the rotation preventing member is formed of a metal material integral with the center shaft. Then, when a twisting impact force at the time of tightening the nut is applied to the center shaft, the twisting impact force transmitted from the center shaft engaging portion can be received by the shape of the rotation prevention member. This makes it difficult for the torsional impact force at the time of assembly to act on the joint between the center shaft and the ceramic heater, and this joint can be protected from damage.

  In addition, the center shaft engaging portion is formed of a metal material integral with the center shaft, and the center shaft does not have a thin-walled portion whose thickness is significantly reduced. Therefore, it is possible to secure the strength of the center shaft against the torsional impact force when tightening the nut and to protect the center shaft from damage.

  Therefore, according to the glow plug of the one aspect, it is possible to protect the center shaft and the joint between the center shaft and the ceramic heater from damage.

  In the glow plug manufacturing method according to the other aspect, as the disposing step, the detent member can be disposed in the disposing recess of the housing when the housing is in a single state. As a result, when the rotation preventing member is arranged in the arrangement recess of the housing, there is no member or the like that becomes an obstacle to the arrangement around it, and this arrangement operation can be facilitated.

  In the insertion step, the center shaft is inserted into the housing in which the rotation prevention member is disposed, and the middle shaft engagement portion is disposed on the inner peripheral side of the rotation prevention member. Thus, the intermediate shaft engaging portion can be disposed on the inner peripheral side of the rotation prevention member in accordance with the operation of inserting the intermediate shaft into the housing. Therefore, the work of assembling the glow plug can be facilitated.

  The manufacturing method of the glow plug of the said other aspect is suitable for manufacture of the glow plug which can protect the joint of an axial center, and an axial center and a ceramic heater from damage.

  The reference numerals in parentheses in each component shown in one aspect and the other aspect of the present invention indicate the correspondence with the reference numerals in the drawings in the embodiment, but each component is limited to only the contents of the embodiment. It is not a thing.

Sectional explanatory drawing which shows the glow plug attached to the plug attachment hole concerning Embodiment 1. FIG. Sectional explanatory drawing which expands and shows the proximal end part of the glow plug concerning Embodiment 1. FIG. Sectional explanatory drawing of the III-III arrow of FIG. 2 which shows the periphery of the rotation preventing member concerning Embodiment 1. FIG. Sectional explanatory drawing which expands and shows the front end side part of the glow plug concerning Embodiment 1. FIG. Sectional explanatory drawing equivalent to the III-III arrow of FIG. 2 which shows the periphery of the other rotation prevention member concerning Embodiment 1. FIG. Sectional explanatory drawing equivalent to the III-III arrow of FIG. 2 which shows the periphery of the other rotation prevention member concerning Embodiment 1. FIG. Sectional explanatory drawing equivalent to the III-III arrow of FIG. 2 which shows the periphery of the other rotation prevention member concerning Embodiment 1. FIG. The graph which shows the relationship between the press-fit displacement amount of an annular metal fitting and press-fit load concerning Embodiment 1. FIG. Sectional explanatory drawing which shows the housing assembly body concerning Embodiment 1. FIG. FIG. 2 is a cross-sectional explanatory view showing a heater assembly according to Embodiment 1. FIG. 5 is a cross-sectional explanatory view showing a state in which the housing assembly is attached to the heater assembly according to the first embodiment. Sectional explanatory drawing which shows the state with which the heater assembly body and the housing assembly body were assembled concerning Embodiment 1. FIG. Sectional explanatory drawing which shows the manufactured glow plug concerning Embodiment 1. FIG. Sectional explanatory drawing which shows the rotation prevention member divided | segmented into two concerning Embodiment 2. FIG. Sectional explanatory drawing which shows the rotation prevention member divided | segmented into four concerning Embodiment 2. FIG. Sectional explanatory drawing which expands and shows the proximal end part of the other glow plug concerning Embodiment 2. FIG. Sectional explanatory drawing which expands and shows the proximal end part of the glow plug concerning Embodiment 3. FIG. Sectional explanatory drawing of the XVIII-XVIII arrow of FIG. 17 which shows the periphery of a rotation preventing member concerning Embodiment 3. FIG. Sectional explanatory drawing which expands and shows the proximal end part of the other glow plug concerning Embodiment 3. FIG. Sectional explanatory drawing of XX-XX arrow of FIG. 19 which shows the periphery of the other rotation prevention member concerning Embodiment 3. FIG.

Preferred embodiments of the above-described glow plug and the method of manufacturing the same will be described with reference to the drawings.
First Embodiment
As shown in FIGS. 1 and 2, the glow plug 1 according to the present embodiment includes a housing 2, a ceramic heater 3, a central shaft 4 and a rotation stopping member 51. The housing 2 is formed in a tubular shape, and is disposed at the outermost periphery of the glow plug 1. The ceramic heater 3 is inserted into the tip of the housing 2. The center shaft 4 is inserted into the base end side L2 of the ceramic heater 3 in the housing 2 and is conducted to the ceramic heater 3. The anti-rotation member 51 is disposed in the gap between the housing 2 and the middle shaft 4 to insulate the housing 2 from the middle shaft 4 and to prevent the middle shaft 4 from rotating relative to the housing 2.

  As shown in FIGS. 2 and 3, on the inner periphery of the proximal end portion of the housing 2, an arrangement concave portion 22 in which the detent member 51 is arranged is formed. On the outer periphery of the middle shaft 4, a middle shaft engaging portion 41 engaged with the rotation preventing member 51 is formed of a metal material integral with the middle shaft 4.

  In the glow plug 1 of the present embodiment, the tip end side L1 is the side of the glow plug 1 on which the ceramic heater 3 is disposed, and the side on the side of the combustion chamber 64 of the engine. The proximal end side L2 is the side opposite to the distal end side L1 and is apart from the combustion chamber 64. The direction in which the central axes of the glow plug 1 and the central shaft 4 extend is referred to as an axial direction L. The distal end side L1 refers to the distal end side L1 in the axial direction L, and the proximal end L2 refers to the proximal end side L2 in the axial direction L.

The glow plug 1 of the present embodiment will be described in detail below.
As shown in FIG. 1, the glow plug 1 is used in an engine such as a diesel engine that is self-ignited in an automobile or the like. The glow plug 1 is disposed in a plug mounting hole 61 provided in a cylinder head 6 of the engine, and is used to heat (preheat) the inside of a combustion chamber 64 of the cylinder head 6 by the ceramic heater 3.

(Ceramic heater 3)
As shown in FIG. 4, the ceramic heater 3 generates heat by energization. The ceramic heater 3 has an insulating rod-like ceramic base 31, a heater element 32 provided on the ceramic base 31, and an anode as a positive side electrode provided at one end of the heater element 32 via a lead portion 331. 33 and a cathode 34 as a negative electrode provided at the other end of the heater element 32 via a lead portion 341.

  The ceramic base 31 is made of a ceramic material. The heater element 32 is embedded in the ceramic base 31. The heater element 32 is made of a metal material which has conductivity and serves as a heating resistor which generates heat when energized. The anode 33 is disposed on the outer periphery of the base end of the ceramic base 31. The cathode 34 is disposed at the proximal end portion of the ceramic base 31 on the outer periphery of the distal end side L1 relative to the anode 33. The ceramic heater 3 is formed in a circular cross section.

(Housing 2)
As shown in FIG. 1, the housing 2 is a component that is disposed at the outermost periphery of the glow plug 1 and is attached to the plug attachment hole 61 of the cylinder head 6. The housing 2 is conducted to the cylinder head 6 and electrically connected to the ground potential. The cathode 34 of the ceramic heater 3 is conducted to the inner peripheral surface of the first housing 2A constituting the housing 2. The cathode 34 of the ceramic heater 3 is electrically connected to the ground potential via the housing 2 and the cylinder head 6. The housing 2 can be made of, for example, a metal material such as S35C, which is a carbon steel material for machine structure.

  As shown in FIGS. 1 and 4, the housing 2 is connected to the first housing 2A mounted on the outer periphery of the ceramic heater 3 and the base end side L2 of the first housing 2A, and the second shaft is inserted It is comprised by the housing 2B. The boundary portion 201 where the first housing 2A and the second housing 2B are joined is joined by laser welding or the like. A tapered contact surface 24 is formed on the outer periphery of the end of the proximal end L2 of the first housing 2A to be in contact with the tapered stepped surface 62 formed on the inner wall surface of the plug mounting hole 61.

  As shown in FIGS. 2 and 3, a polygonal housing-shaped portion 23 disposed outside the cylinder head 6 is formed on the outer periphery of the end of the proximal end L2 of the second housing 2B. The housing shape portion 23 is a portion where the tightening tool is engaged when the housing 2 is attached to the plug mounting hole 61. The housing shape part 23 of this form has a hexagonal cross-sectional shape. The size of the housing shape part 23 of this embodiment is HEX10. In other words, the housing shape portion 23 is a hexagonal shape having a two-face width of 10 mm. As shown in FIG. 1, an external thread 25 formed in the plug mounting hole 61 and screwed with the threaded portion 63 is provided at a position on the distal end side L1 relative to the housing shape 23 on the outer periphery of the second housing 2B. It is formed. In addition, the housing shape part 23 can also be formed in cross-sectional shape, such as a square, in which a clamping tool is engaged.

  As shown in FIG. 1, on the inner peripheral side of the first housing 2A, a tip side insertion hole 21A through which the ceramic heater 3 is inserted is formed. On the inner peripheral side of the second housing 2B, a base end side insertion hole 21B through which the middle shaft 4 is inserted is formed. As shown in FIG. 2, the disposition recess 22 is formed to face the inner peripheral side of the housing shape portion 23 in the proximal end insertion hole 21B of the second housing 2B. The placement recess 22 is formed by increasing the diameter of the end of the proximal end L2 in the proximal insertion hole 21B. A stepped bottom surface 221 for locking the anti-rotation member 51 is formed on the end surface of the tip end side L1 of the disposition concave portion 22.

  The arrangement recess 22 of this embodiment is formed on the inner peripheral surface of the circular cross section in consideration of the ease of processing. Therefore, in the present embodiment, when the detent member 51 is compressed in the axial direction L using an annular metal fitting 52 described later, and a twisting force that clamps the outer nut 56 on the terminal male screw portion 42 described later acts on the center shaft 4 The anti-rotation member 51 disposed in the placement recess 22 is prevented from rotating with the center shaft 4.

(Center 4)
As shown in FIGS. 1 and 2, the middle shaft 4 is disposed on the inner peripheral side of the housing 2, in other words, the proximal end insertion hole 21 B of the second housing 2 B, and the anode 33 of the ceramic heater 3 is provided outside the glow plug 1. It is a component for electrically connecting to An electrode fitting 43 in contact with the anode 33 is attached to the tip of the center shaft 4. The anode 33 of the ceramic heater 3 is conducted to the electrode fitting 43. The anode 33 of the ceramic heater 3 is connected to an external power source 7 through the electrode fitting 43 and the center shaft 4.

  At the outer periphery of the base end portion of the center shaft 4, a terminal male screw portion 42 in which the inner nut 55 and the outer nut 56 are screwed is formed. An external thread portion 421 is formed on the outer periphery of the terminal external thread portion 42. The size of the male screw portion 421 is M4 (diameter: 4 mm). The connection terminal 71 of the external power source 7 is attached to the terminal male screw portion 42, and the connection terminal 71 is attached by tightening the outer nut 56. The center shaft engaging portion 41 is formed of a metal material integral with the center shaft 4 as a portion left without being cut when the center shaft 4 is cut. The center shaft engaging portion 41 is provided so as to protrude to the outer peripheral side at a position on the tip end side L1 relative to the terminal male screw portion 42.

  As shown in FIG. 3, the outer periphery of the center shaft engaging portion 41 in the present embodiment has a rectangular cross-sectional shape as a polygonal shape. The center shaft engaging portion 41 has a plurality of detent surfaces 411 forming a polygonal shape, and the corners 412 between the detent surfaces 411 are rounded. The locking surface 411 is formed as a flat surface. The corner portion 412 is formed in an arc shape along an imaginary circle E drawn around the central axis of the center shaft 4 in order to avoid local stress in the detent member 51. As a reference, the diameter of the imaginary circle E in this embodiment is φ 4.8 mm, and the width of the detent surfaces 411 in parallel positions in this embodiment is 4 mm.

(Anti-rotation member 51)
As shown in FIG. 2 and FIG. 3, the anti-rotation member 51 secures the insulation between the housing 2 and the center shaft 4, and is a resin material or ceramic material having a strength sufficient to withstand the torsional force transmitted from the center shaft 4. Is formed as a molded body. The rotation prevention member 51 is formed in an annular shape, and is formed in such a shape as to fill a gap between the inner periphery of the disposition recess 22 and the outer periphery of the center shaft 4. The outer periphery of the locking member 51 is formed in a circular cross-sectional shape, and the inner peripheral hole 510 of the locking member 51 is formed in a polygonal shape along the outer peripheral shape of the center shaft engaging portion 41. The inner circumferential hole 510 of the detent member 51 has a rectangular cross-sectional shape as a polygonal shape having a plurality of detent surfaces 511 and rounded inner corners 512.

  The plurality of detent surfaces 411 of the center shaft engaging portion 41 and the plurality of detent surfaces 511 of the detent member 51 face each other. By the facing of the detent surfaces 411 and 511, the detent of the center shaft 4 by the detent member 51 is performed. Thereby, the rotation prevention of the center shaft 4 can be performed more reliably.

  As shown in FIG. 3, the inner circumferential hole 510 of the rotation prevention member 51 has a size that allows insertion of the terminal male screw portion 42 of the center shaft 4 and the center shaft engaging portion 41 in order to facilitate assembly work of the glow plug 1. Is formed. More specifically, the diameter φD1 of the inscribed circle F1 in the polygonal inner circumferential hole 510 of the rotation preventing member 51 is larger than the diameter φD2 of the inscribed circle F2 in the polygonal central shaft engaging portion 41, and is inscribed. The diameter φD2 of the circle F2 is larger than the outer diameter φD3 of the terminal male screw portion 42. That is, in the present embodiment, there is a relationship of φD1> φD2> φD3. The rotation prevention member 51 can be made of, for example, a phenol resin as a resin material, and can also be made of a sintered body of alumina as a ceramic material.

  The outer periphery of the center shaft engaging portion 41 and the inner peripheral hole 510 of the rotation preventing member 51 have a cross section such as a pentagon or a hexagon as shown in FIGS. can do. Also in this case, the outer periphery of the center shaft engaging portion 41 has the detent surface 411 and the rounded corner portion 412, and the inner peripheral hole 510 of the detent member 51 follows the outer peripheral shape of the center shaft engaging portion 41. It has the following shape. For reference, the diameter of the pentagonal virtual circle E of the present embodiment is φ4.6 mm, and the diameter of the hexagonal virtual circle E of the present embodiment is φ4.4 mm. Further, the radius from the center to the detent surface 411 in the case of the pentagon is 2 mm, and the width of the detent surface 411 in parallel positions in the case of the hexagon is 4 mm.

  Further, as shown in FIG. 7, the outer periphery of the center shaft engaging portion 41 and the inner peripheral hole 510 of the rotation preventing member 51 have a shape in which a pair of parallel rotation preventing surfaces 511 is formed with respect to the circular outer peripheral surface. It can also be done. The pair of rotation preventing surfaces 511 can be formed continuously from the center shaft engaging portion 41 to the terminal male screw portion 42. In this case, the pair of detent surfaces 411 of the center shaft engaging portion 41 and the pair of detent surfaces 511 of the detent member 51 face each other, and the detent member 51 detents the center shaft 4. As a reference, the diameter of the imaginary circle E in this embodiment is φ4 mm, and the width of the pair of detent surfaces 411 in this embodiment is 3.3 mm.

  The outer periphery of the center shaft engaging portion 41 and the inner peripheral hole 510 of the rotation prevention member 51 have at least one rotation prevention surface facing each other in order to prevent rotation of the center shaft 4 by the rotation prevention member 51. Just do it. Further, in order to prevent the rotation of the center shaft 4 by the rotation preventing member 51, the outer periphery of the center shaft engaging portion 41 and the inner peripheral holes 510 of the rotation preventing member 51 intersect various imaginary circles around their central axes. It may have a face.

(Circular fitting 52)
As shown in FIG. 2, an annular metal fitting 52 in which the center shaft 4 is inserted is disposed on the base end side L2 of the rotation preventing member 51 in the housing 2. The annular fitting 52 is a component for pressing the detent member 51 in the axial direction L. The annular fitting 52 of the present embodiment is made of a metal material, and is formed in an annular shape. The annular fitting 52 can be made of, for example, SUS430, which is a stainless steel material. The annular fitting 52 is disposed adjacent to the base end side L 2 of the rotation preventing member 51 in the disposition recess 22. The annular metal fitting 52 is press-fit into the placement recess 22 in a state in which the anti-rotation member 51 is held between the annular fitting 52 and the step bottom surface 221 of the placement recess 22.

  By press-fitting the annular fitting 52 into the placement recess 22, the anti-rotation member 51 and the annular fitting 52 are fixed to the second housing 2B in the anti-rotation state in the single housing state of the second housing 2B. be able to. As a result, the management of the assembled state can be simplified, and along with this, the quality of the assembly can be improved.

  The outer diameter of the annular metal fitting 52 before press-fitting is slightly larger than the inner diameter of the arrangement recess 22. Then, after the annular fitting 52 is press-fit into the placement recess 22, the annular fitting 52 is fixed to the placement recess 22, and the anti-rotation member 51 is fixed to the inside of the placement recess 22 by the annular fitting 52. In addition, the rotation prevention member 51 receives an axial force from the annular fitting 52 when the annular fitting 52 is press-fit into the placement recess 22, and is held between the step bottom surface 221 of the placement recess 22 and the annular fitting 52. , The detent to the housing 2 is performed.

  Further, as shown in FIG. 2, in order to facilitate insertion of the center shaft engaging portion 41 into the inner circumferential hole 510 of the rotation preventing member 51 disposed in the placement recess 22, the inner diameter of the annular fitting 52 is It is larger than the outer diameter of the inner circumferential hole 510 of the stopper member 51.

(Sealing material 53)
As shown in FIG. 2, a seal member 53 for preventing water or the like from entering the gap between the housing 2 and the center shaft 4 from the outside of the glow plug 1 is disposed in the gap between the annular fitting 52 and the center shaft 4. ing. The sealing material 53 also has a function of securing the insulation between the annular fitting 52 and the center shaft 4. The sealing material 53 of this embodiment is made of liquid sealing rubber. The sealing material 53 can be made of various rubbers, resins or the like.

(Insulation bush 54)
An insulation bush 54 in which the terminal screw portion 42 of the center shaft 4 is inserted is disposed at the proximal end L2 of the annular fitting 52 and at the proximal end of the disposition recess 22. The insulating bush 54 is a component for insulating the center shaft 4 and the inner nut 55 from the second housing 2 B and the annular fitting 52. The insulating bush 54 is made of various resin materials or ceramic materials.

(Assembly structure of detent member 51 etc.)
As shown in FIG. 2, the detent member 51, the annular fitting 52, the seal member 53 and the insulating bush 54 are disposed at the proximal end of the placement recess 22 and the second housing 2 B, and the detent member 51 and the annular fitting In a state where the inner shaft 4 is inserted to the inner peripheral side of the seal member 53 and the insulating bush 54, the inner nut 55 screwed to the terminal male screw portion 42 is tightened.

  The step bottom surface 221 of the arrangement recess 22 is formed on a smooth surface as a plane perpendicular to the axial direction L. The end face of the rotation preventing member 51 and the end face of the annular fitting 52 are also formed on a smooth surface as a plane perpendicular to the axial direction L. And, when the detent member 51 is sandwiched between the step bottom surface 221 and the annular fitting 52, the detent member 51 is compressed along the axial direction L, and a local stress acts on the detent member 51. Can be prevented.

  The locking member 51 is locked against the housing 2 by the residual compressive load P2 acting on the locking member 51 in the axial direction L from the annular fitting 52 when the annular fitting 52 is press-fit into the disposition recess 22. There is. In FIG. 8, when the annular fitting 52 is press-fit into the placement recess 22, the press-fit displacement amount x (mm) of the annular fitting 52 in the axial direction L and the press-fit load P (N) for press-fitting the annular fitting 52. Show the relationship with In the first process K1 until the annular metal fitting 52 abuts the rotation preventing member 51 when the annular metal fitting 52 is press-fitted into the arrangement concave portion 22, the press-fit displacement amount x of the annular metal fitting 52 to the arrangement concave portion 22 increases. The press-fit load P1 applied to the annular metal fitting 52 increases as the annular fitting 52 increases.

  Then, when the annular metal fitting 52 abuts on the rotation preventing member 51, as the second process K2, the press-in load P acting on the annular metal fitting 52 is received by the rotation preventing member 51, and the press-in load P applied to the annular metal fitting 52 sharply. To increase. At this time, the press-fit load P acting on the detent member 51 is the residual compression load P2 acting on the detent member 51. Then, as the press-fit displacement amount x of the annular fitting 52 pressing the detent member 51 increases, the residual compression load P2 acting on the detent member 51 increases.

  In this embodiment, the residual compression load P2 acting on the detent member 51 is generated when the outer nut 56 is seated on the connection terminal 71 when the outer nut 56 is tightened to the terminal male screw portion 42 of the center shaft 4 by a tightening tool. The anti-rotation member 51 is set to a size not to rotate by the twisting force. When setting the residual compression load P2 for locking the rotation preventing member 51, as shown in FIGS. 2 and 3, between the end face of the rotation preventing member 51 and the step bottom surface 221 of the arrangement recess 22. The friction force in the circumferential direction C, which acts on the

  That is, by adjusting the residual compressive load P2 acting on the detent member 51, and the coefficient of friction in the circumferential direction C acting between the end face of the detent member 51 and the stepped bottom surface 221, the rotation with respect to the housing 2 is achieved. The locking member 51 can be locked. For example, if the surface roughness of the end face of the detent member 51 and the bottom surface 221 of the step is set roughly, detent member 51 can be prevented from deviating from the housing 2 also by setting the residual compressive load P2 as low as possible. it can.

  In addition, between the arrangement | positioning recessed part 22 of the housing 2, and the rotation prevention member 51, the rotation prevention by a shape may be performed. For example, by forming a non-circular shape-changed portion on the outer periphery of the rotation preventing member 51 and the inner periphery of the disposition recess 22, the rotation preventing member 51 can be prevented from rotating relative to the housing 2. In addition, for example, by arranging another member such as a key member at the boundary position between the rotation preventing member 51 and the disposition recess 22, the rotation preventing member 51 can be prevented from rotating relative to the housing 2.

(Production method)
Next, a method of manufacturing the glow plug 1 will be described.
First, as a disposing step, as shown in FIG. 9, the detent member 51 is disposed in the disposition concave portion 22 of the proximal end insertion hole 21B of the second housing 2B, and the disposition concave portion from the proximal end L2 of the detent member 51 The annular metal fitting 52 is press-fit into the inside 22. Then, the housing assembly 11 in which the rotation preventing member 51 and the annular fitting 52 are disposed is formed on the second housing 2B.

  In the arranging step, when the second housing 2B is in a single state, the detent member 51 can be arranged in the arranging recess 22 of the second housing 2B, and the annular fitting 52 can be press-fit. Thereby, when the arrangement of the rotation prevention member 51 and the press fitting of the annular metal fitting 52 are performed, there is no member or the like that becomes an obstacle to the arrangement and the press fit around them, and this arrangement / press fit operation can be facilitated. it can.

  Further, as shown in FIG. 10, as the heater assembling step, the ceramic heater 3 is inserted into the distal end side insertion hole 21A of the first housing 2A separately from the disposing step, The electrode metal fitting 43 is attached to the base end of the ceramic heater 3. Then, the heater assembly 12 in which the first housing 2A, the ceramic heater 3, the middle shaft 4 and the electrode fitting 43 are assembled is formed. The anode 33 of the glow plug 1 and the electrode fitting 43, and the cathode 34 of the glow plug 1 and the housing 2 can be electrically connected to each other through a brazing material or the like.

  Next, as shown in FIG. 11, the housing assembly 11 is attached to the heater assembly 12 in the insertion step. At this time, the center shaft 4 of the heater assembly 12 is inserted into the second housing 2 B, and the inner peripheral hole 510 of the rotation prevention member 51 in the housing assembly 11 is a terminal screw of the center shaft 4 in the heater assembly 12. The portion 42 and the center shaft engaging portion 41 are inserted. The center shaft engaging portion 41 is disposed in the inner circumferential hole 510 of the rotation preventing member 51, and the base end surface 202 of the first housing 2A and the tip end surface 203 of the second housing 2B face each other.

  In the insertion step, the intermediate shaft engaging portion 41 can be disposed in the inner circumferential hole 510 of the rotation prevention member 51 in accordance with the operation of inserting the intermediate shaft 4 into the second housing 2B. Therefore, the work of assembling the glow plug 1 can be facilitated.

  Next, as shown in FIG. 12, laser welding or the like is performed on the boundary portion 201 between the base end surface 202 of the first housing 2A and the tip end surface 203 of the second housing 2B to join the first housing 2A and the second housing 2B. To form the housing 2. Next, a liquid seal rubber as the seal member 53 is filled in the gap formed between the annular fitting 52 and the center shaft 4 in the housing 2. Then, the gap between the annular metal fitting 52 and the center shaft 4 is filled with the sealing material 53.

  Next, as shown in FIG. 13, the insulating bush 54 is attached to the terminal male screw portion 42 of the middle shaft 4, and the inner nut 55 is screwed into the terminal male screw portion 42. Thus, the glow plug 1 is manufactured.

(Install the glow plug 1)
Further, as shown in FIG. 1, the glow plug 1 is used by being attached to the plug attachment hole 61 of the cylinder head 6. When attaching the glow plug 1 to the plug mounting hole 61, the ceramic heater 3 and the housing 2 of the glow plug 1 are inserted into the plug mounting hole 61, and the external thread 25 of the housing 2 is an internal thread of the plug mounting hole 61. Screw on the part 63. At this time, a worker or the like engages a tightening tool with the housing shape portion 23 of the housing 2 and rotates the glow plug 1 using the tightening tool, so that the male screw portion 25 of the housing 2 is a female screw of the plug mounting hole 61 It can be screwed into the part 63.

  Next, as shown in the same figure, the operator mounts the connection terminal 71 of the external power supply 7 to the terminal male screw portion 42 of the center shaft 4 of the glow plug 1 and attaches the outer nut 56 to the terminal male screw portion 42. Screw them together. Then, the outer nut 56 is rotated by the tightening tool to fasten the outer nut 56 to the terminal male screw portion 42. Thus, the connection terminal 71 is held between the inner nut 55 already screwed to the terminal male screw portion 42 and the outer nut 56, and the connection terminal 71 is electrically connected to the center shaft 4 of the glow plug 1. . Thus, the glow plug 1 is attached to the plug attachment hole 61.

  The attachment of the connection terminal 71 to the terminal male screw portion 42 and the tightening of the outer nut 56 may be performed on the glow plug 1 before being attached to the plug attachment hole 61.

(Action effect)
In the glow plug 1 of the present embodiment, paying attention to the shape and strength of the portion where the center shaft 4 and the detent member 51 engage, when the outer nut 56 is tightened to the terminal male screw portion 42 of the center shaft 4, The intermediate shaft 4 and the joint between the electrode fitting 43 of the central shaft 4 and the ceramic heater 3 are protected from the torsional impact force that acts.

  In the glow plug 1 of the present embodiment, the center shaft engaging portion 41 engaged with the anti-rotation member 51 is formed on the outer periphery of the center shaft 4 by a metal material integral with the center shaft 4. Then, when a twisting impact force is applied to the center shaft 4 at the time of tightening the nut, the twisting impact force is determined by the plurality of detent surfaces 511 of the detent member 51 facing the detent surfaces 411 of the center shaft engaging portion 41. It can be received. As a result, the torsional impact force at the time of tightening the nut is less likely to act on the joint of the electrode fitting 43 attached to the center shaft 4 and the anode 33 of the ceramic heater 3 and these joints can be protected from damage. .

  Further, the center shaft engaging portion 41 is formed of a metal material integrated with the center shaft 4, and the center shaft 4 does not have a thin-walled portion whose thickness is significantly reduced. Therefore, it is possible to secure the strength of the center shaft 4 against the torsional impact force when tightening the nut and to protect the center shaft 4 from damage.

  In addition, by forming the disposition recess 22 on the inner peripheral side of the housing shape portion 23 of the housing 2, the housing shape portion 23 is slightly thinned. However, the annular shape 52 is reinforced by the annular fitting 52 by press-fitting the annular fitting 52 into the arrangement recess 22. As a result, when the glow plug 1 is attached to the plug attachment hole 61, when the housing 2 receives the rotational torque by the tightening tool engaged with the housing shape portion 23, the torsional deformation of the housing 2 is suppressed.

  When the glow plug 1 is mounted in the plug mounting hole 61, the contact between the tapered step surface 62 of the plug mounting hole 61 and the tapered contact surface 24 of the housing 2 is well formed. By the formation of the contact state, the sealing function for sealing the inside of the combustion chamber 64 of the cylinder head 6 can be secured.

  As described above, according to the glow plug 1 of the present embodiment, the joint between the center shaft 4 and the electrode fitting 43 attached to the center shaft 4 and the anode 33 of the ceramic heater 3 is protected from damage when tightening the nut. Can.

Second Embodiment
The present embodiment shows a case where a device different from that of the first embodiment is applied to the rotation preventing member 51, the terminal external thread portion 42 of the middle shaft 4, or the annular fitting 52.

  The rotation prevention member 51 can be formed not only in an annular shape as an integral shape, but also in combination with a plurality of divided bodies 513 as shown in FIGS. 14 and 15. In this case, the detent member 51 can be divided into divided states at appropriate places in the circumferential direction C. The rotation prevention member 51 can be divided into, for example, a plurality of divided bodies 513 such as two divisions or four divisions.

  When the outer nut 56 is tightened to the terminal male screw portion 42 by dividing the detent member 51, the twisting force acting on the detent member 51 from the center shaft 4 is distributed to the plurality of divided bodies 513 of the detent member 51. It can be done. This makes it possible to prevent the rotation prevention member 51 made of a resin material or a ceramic material from being broken by a twisting force.

  Further, as shown in FIG. 16, the terminal male screw portion 42A can be formed separately from the center shaft 4 and integrated with the center shaft 4. The divided terminal male screw portion 42A has, for example, a shape having a cylindrical portion 422 mounted on the outer periphery of the base end portion 44 of the center shaft 4 and an external thread portion 423 connected to the proximal end L2 of the cylindrical portion 422. It can be formed. The cylindrical portion 422 can be deformed so as to reduce the outer diameter and caulked and fixed to the outer periphery of the proximal end portion 44 of the center shaft 4. The caulking fixing of the cylindrical portion 422 can be performed after the center shaft 4 is inserted into the inner peripheral side of the housing 2.

  By dividing the terminal male screw portion 42A from the middle shaft 4, the middle shaft 4 and the middle shaft engaging portion 41 can be thinned while maintaining the size of the screw formed on the terminal male screw portion 42A. Further, by thinning the center shaft engaging portion 41, it is possible to increase the thickness of the detent member 51 and the housing shape portion 23, and it is possible to increase the strength of the detent member 51 and the housing shape portion 23. become. As a reference, the outer diameter of the base end portion 44 of the center shaft 4 of this embodiment is φ3.4 mm, and the diameter of the imaginary circle E for forming the corner portion 412 of the center shaft engaging portion 41 of this embodiment is φ4 mm, The width of the detent surface 411 in the mutually parallel position of this form is 3.5 mm.

  The annular fitting 52 can also be joined to the housing 2 by laser welding or the like after being press-fitted into the arrangement recess 22. This joining can be performed on at least a part of the boundary between the annular fitting 52 and the housing 2 in the circumferential direction C. In this case, the annular metal fitting 52 can be prevented from being loosened from the housing 2.

  The other configurations, effects, and the like of the glow plug 1 of the present embodiment are the same as those of the first embodiment. Also in this embodiment, the constituent elements indicated by the same reference numerals as the reference numerals in the first embodiment are the same as those in the first embodiment.

Embodiment 3
In this embodiment, as shown in FIG. 17 and FIG. 18, the locking member 51 is locked to the annular fitting 52 on the inner peripheral side of the annular fitting 52 disposed in the placement recess 22. It shows about the case where it arranges by.

  The outer periphery of the annular fitting 52 is formed in a circular cross section, and is press-fitted into the arrangement recess 22 having a circular cross section. The inner circumference of the annular fitting 52 is formed in a cross section having groove portions 521 recessed toward the outer circumference at a plurality of locations in the circumferential direction C. Further, between the groove portions 521 in the circumferential direction C, a convex portion 522 is formed. The groove part 521 and the convex part 522 of this form are formed in multiple places of the circumferential direction C at equal intervals. Further, the groove portion 521 and the convex portion 522 are formed in a part of the annular metal fitting 52 in the axial direction L.

  As shown in FIG. 17 and FIG. 18, a part of the rotation preventing member 51 is formed as a projection 514 which enters the groove 521. Further, between the protrusions 514 in the circumferential direction C, a recess 515 in which the protrusion 522 is disposed is formed. The arrangement recess 22 of this embodiment is formed to have a depth substantially the same as the length of the annular fitting 52 from the end face of the proximal end L2 of the second housing 2B. A seal material recess 26 for holding the seal material 53 is formed on the front end side L1 of the placement recess 22. As a reference, the diameter of an imaginary circle E for forming the corner portion 412 of the center shaft engaging portion 41 of the present embodiment is φ4 mm, and the width of the rotation stopping surface 411 in the mutually parallel position of the present embodiment is 3.5 mm. is there.

  The inner diameter of the sealing material recess 26 is larger than the inner diameter of the proximal end insertion hole 21 B and smaller than the inner diameter of the arrangement recess 22. In the sealing material recess 26, an O-ring 57 made of a rubber material and an O-ring 57 are prevented from protruding from the proximal end L2 to the proximal insertion hole 21B in order from the proximal end L2 (seat the O-ring 57). A bake washer 58 is disposed. The bake washer 58 may be a washer having an insulating property.

  Further, as shown in FIG. 17, the end of the proximal end L2 of the annular fitting 52 is joined to the end of the proximal end L2 of the second housing 2B by laser welding or the like. This joining can be performed on the entire circumference or a part of the circumferential direction C of the annular fitting 52. The annular metal fitting 52 of this embodiment is located at the end of the proximal end L2 of the second housing 2B, so it is easy to join by welding or the like. The annular fitting 52 can be joined to the second housing 2B by resistance welding or the like instead of laser welding.

  In addition, the entire annular fitting 52 is embedded in the disposition recess 22. On the other hand, the rotation preventing member 51 is provided so as to protrude from the annular fitting 52 to the proximal end L2. The anti-rotation member 51 covers the outer periphery of a portion in the axial direction L at the proximal end portion 44 of the center shaft 4 that protrudes from the second housing 2B to the proximal end L2. With this configuration, it is possible to increase the creepage distance for insulating the central shaft 4 connected to the positive potential of the power source 7 or the like and the second housing 2B connected to the negative potential as the ground. Therefore, the leakage between the center shaft 4 and the second housing 2B can be prevented more reliably.

  When press-fitting the annular metal fitting 52 into the placement recess 22, a press-fit margin of 30 to 100 μm can be set. When this press-fit is performed, a lubricant can be applied between the outer periphery of the annular fitting 52 and the inner periphery of the placement recess 22 to reduce variations in press-fit load.

  In the glow plug 1 of the present embodiment, the detent member 51 and the annular fitting 52 are integrated as an insert-molded product of a resin that constitutes the detent member 51. With this configuration, the detent member 51 in which the detent is performed on the annular fitting 52 can be easily formed. In addition, when performing insert molding, the annular metal fitting 52 is arrange | positioned to a shaping | molding die, and resin which comprises the rotation prevention member 51 is filled in a shaping | molding die. Then, the detent member 51 integrated with the annular fitting 52 is taken out of the mold.

  Further, in the glow plug 1 of the present embodiment, since the rotation preventing member 51 is prevented from rotating with respect to the annular fitting 52, the rotation preventing member 51 is prevented from rotating without applying a compressive load to the rotation preventing member 51. It can be performed. Thereby, damage to the rotation prevention member 51 can be prevented, and the rotation prevention member 51 can be easily assembled to the second housing 2B.

  In addition, the annular metal fitting 52 and the rotation preventing member 51 can be prevented from rotating with respect to the second housing 2B by press-fitting the annular metal fitting 52 into the arrangement recess 22. Furthermore, by joining the annular fitting 52 to the second housing 2B, the rotation of the annular fitting 52 and the anti-rotation member 51 relative to the second housing 2B can be further reliably secured.

  Further, the engagement between the rotation preventing member 51 and the annular fitting 52 for preventing rotation of the rotation preventing member 51 with respect to the annular fitting 52 can have various shapes. For example, as shown in FIGS. 19 and 20, the annular fitting 52 is press-fit only into the portion L2 in the axial direction L of the placement recess 22 and the placement recess 22 includes the outer periphery of the rotation prevention member 51 and the ring. The outer periphery of the fitting 52 can be made to face.

  Further, at the proximal end portion of the annular fitting 52, a bent portion 523 which is bent toward the outer peripheral side can be formed so as to face the end face of the proximal end L2 of the second housing 2B. Also in this case, the annular fitting 52 is press-fit into the arrangement recess 22. Further, in this case, the bent portion 523 of the annular fitting 52 can be joined to the second housing 2B. Also in this case, the other configurations are the same as those in FIGS. 17 and 18.

  The other configurations, effects, and the like of the glow plug 1 of the present embodiment are the same as those of the first embodiment. Also in this embodiment, the constituent elements indicated by the same reference numerals as the reference numerals in the first embodiment are the same as those in the first embodiment.

  The present invention is not limited to only the embodiments, and it is possible to configure different embodiments without departing from the scope of the invention. Further, the present invention includes various modifications, modifications within the equivalent range, and the like.

DESCRIPTION OF SYMBOLS 1 glow plug 2 housing 22 arrangement recessed part 23 housing shape part 3 ceramic heater 4 middle shaft 41 middle shaft engagement part 51 rotation prevention member

Claims (9)

A cylindrical housing (2),
A ceramic heater (3) inserted into the end of the housing;
An inner shaft (4) inserted into the base end side (L2) of the ceramic heater and electrically conducted to the ceramic heater in the housing;
And a detent member (51) disposed in a gap between the housing and the middle shaft, which insulates the housing from the middle shaft and performs rotation of the middle shaft with respect to the housing.
The inner periphery of the proximal end of the housing is provided with an arrangement recess (22) in which the locking member is arranged,
A glow plug (1), wherein an inner shaft engaging portion (41) engaged with the anti-rotation member is formed on the outer periphery of the inner shaft by a metal material integral with the inner shaft.   The glow plug according to claim 1, wherein the outer periphery of the center shaft engaging portion and the inner circumferential hole (510) of the rotation prevention member are formed in a shape having rotation prevention surfaces (411, 511) facing each other. On the outer periphery of the proximal end portion of the housing, a polygonal housing shape portion (23) disposed outside the cylinder head (6) is formed,
The glow plug according to claim 1, wherein the placement recess is formed to face the inner circumferential side of the housing shape portion. An annular metal fitting (52) through which the center shaft is inserted is disposed on the proximal end side of the rotation preventing member in the housing,
The glow plug according to any one of claims 1 to 3, wherein the rotation preventing member is fixed to the housing by being held between the disposition recess and the annular fitting.   The glow plug according to claim 4, wherein a sealing material (53) is disposed in a gap between the annular metal fitting and the central shaft.   The said rotation prevention member is arrange | positioned in the state in which rotation prevention was performed with respect to the said cyclic metal fitting on the inner peripheral side of the cyclic metal fitting (52A, 52B) arrange | positioned in the said arrangement | positioning recessed part. The glow plug according to any one of 3.   The glow plug according to claim 6, wherein the detent member and the annular metal fitting are integrated as an insert-molded product of a resin that constitutes the detent member.   The glow plug according to claim 6 or 7, wherein the annular metal fitting is press-fitted into the arrangement recess of the housing or joined to the housing. A cylindrical housing (2),
A ceramic heater (3) inserted into the end of the housing;
An inner shaft (4) inserted into the base end side (L2) of the ceramic heater and electrically conducted to the ceramic heater in the housing;
A glow plug (1) comprising: a rotation stopping member (51) disposed in a gap between the housing and the middle shaft, insulating the housing from the middle shaft, and stopping the rotation of the middle shaft with respect to the housing Method,
Placing the anti-rotation member in a placement recess (22) formed on the inner periphery of the proximal end of the housing;
Inserting the middle shaft into the housing, and disposing a middle shaft engaging portion (41) formed on the outer periphery of the middle shaft by a metal material integral with the middle shaft on the inner peripheral side of the rotation preventing member And, a method of manufacturing a glow plug.

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