JP6030409B2 - Glow plug and method of manufacturing glow plug - Google Patents

Description

  The present invention relates to a glow plug used for assisting starting of a diesel engine and a method for manufacturing the same.

  A glow plug used to assist the starting of a diesel engine holds a heater that generates heat by conduction on the front end side of a housing (for example, a metal shell), and the front end of the heater is placed in the combustion chamber of the engine. Use with protruding. In addition, a metal conductive member (for example, a rod-shaped central shaft) that is electrically connected to the terminal of the heater and extends toward the rear end side in the axial direction is inserted into the housing. Further, on the rear end side of the housing, a terminal member that is connected to the rear end portion of the middle shaft and is electrically connected to the heater via the middle shaft is disposed. This terminal member is used for electrical connection with the outside.

  In some glow plugs, when the heater is held by the housing, the heater is held by a cylindrical outer cylinder, and the heater is held by the housing via the outer cylinder. For example, in Patent Document 1, a heating element 30 (heater) is inserted into an inner hole of a sleeve 20 (outer cylinder) so that one end 31 of the sleeve 20 protrudes from one end 21 of the sleeve 20. A glow plug is disclosed in which the sleeve 20 is inserted into the housing 10 with one end 21 side of the sleeve 10 protruding from the one end 11 of the housing 10. Here, the sleeve 20 and the housing 10 are fixed by press fitting or brazing of the insertion portion.

JP 2002-228153 A

By the way, in the glow plug that holds the heater in the housing via the outer cylinder and further fixes the outer cylinder to the housing by press-fitting, friction caused by contact between the housing and the outer cylinder at the time of press-fitting is provided. The occurrence of so-called “galling” that causes plastic deformation due to an increase in force and makes insertion difficult becomes a problem.
Specifically, when a glow plug is configured by press-fitting the outer cylinder into the housing, in order to ensure adhesion between the housing and the outer cylinder, in addition to the dimensional accuracy of both, the surface accuracy is also excellent. In addition, it is necessary to secure a press-fitting allowance longer than a predetermined length. However, if they are in close contact at the press-fitting stage, there will be less lubricating oil (lubricant) interposed between them, and sufficient lubrication will not be possible, and galling will occur during press-fitting and the outer cylinder will be fully press-fitted. It becomes difficult.
In particular, in the case of a ceramic glow plug, an outer cylinder in which a hard ceramic heater is press-fitted is press-fitted into the housing, so that the outer cylinder is not easily deformed (reduced in diameter) during press-fitting. "Scratch" is likely to occur.
When such “galling” occurs, even if press-fitting is possible, the stress distribution of the surface pressure between the housing and the outer cylinder after press-fitting is uniform in the axial direction along the axis and in the circumferential direction around the axis. It does not become a thing and causes partial imbalance. For this reason, there is a possibility that the reliability of the glow plug may be lowered due to cracks in the outer cylinder and the heater held by the outer cylinder when used for a long period of time.

  The present invention has been made in view of the present situation, and an object of the present invention is to provide a highly reliable glow plug and a method for manufacturing the same, while the outer cylinder holding the heater is press-fitted into the housing. .

One aspect thereof is a cylindrical shape having a heater that generates heat when energized and a cylindrical hole penetrating in the axial direction along the axis of the heater, and the heater is projected into the cylindrical hole in a state in which the tip of the heater protrudes. And an axial hole extending in the axial direction. The outer cylinder is press-fitted into the axial hole from its own tip side, and the inner peripheral surface of the axial hole which is a pressure contact surface A housing in which an inner peripheral pressure contact surface and an outer peripheral pressure contact surface of the outer peripheral surface of the outer cylinder are pressed against each other and holding the heater via the outer cylinder, and the outer peripheral pressure contact surface of the outer cylinder and At least one of the inner circumferential pressure contact surfaces of the shaft hole is not formed with a recess formation region in which a recess for holding a lubricant that reduces friction during the press-fitting is formed in the axial direction, and the recess. First, close contact with the pressure contact surface of the other party, and Of the recess-formed region to seal the shaft hole hermetically, only including, when said outer peripheral pressing surface of the outer cylinder having the recess formed region and the recess-free region is the peripheral welding of the outer tube Of the surfaces, the axially rear end side from the recess non-formation region is all the recess formation region, and the inner peripheral pressure contact surface of the shaft hole of the housing defines the recess formation region and the recess non-formation region. When it has, it is a glow plug which makes all the said axial direction front end side the said recessed part formation area rather than the said recessed part formation area among the said internal peripheral press-contact surfaces of the said shaft hole .

As described above, when the outer cylinder is press-fitted into the shaft hole of the housing, the lubrication may not be sufficient and galling may occur.
In contrast, in this glow plug, at least one of the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the housing shaft hole, which is the pressure contact surface, alleviates friction when the outer cylinder is press-fitted into the housing shaft hole. A recessed portion forming region in which a recessed portion for holding the lubricant to be formed is formed. The lubricant includes a liquid (lubricant), a semi-solid such as grease, and a solid such as wax.
This reduces friction with the lubricant held in the recesses, prevents the occurrence of galling, and enables proper press-fitting, so that the stress distribution of the surface pressure between the housing and the outer cylinder after press-fitting As a result, the outer cylinder and the heater are not easily cracked, and the glow plug is highly reliable.
On the other hand, in addition to the recess forming area, the press contact surface also has a recess non-forming area where no recess is formed. The shaft hole can be hermetically sealed. This also prevents foreign matter from entering the housing through the recess from the front end of the housing.

  In addition, as a recessed part, for example, a large number of hollows arranged in a dotted shape in the recessed part forming region of the outer circumferential pressure contact surface or the inner circumferential pressure contact surface, or a plurality of linear shapes extending in at least one of the axial direction and the circumferential direction of the axial line A concave groove is mentioned. More specifically, a plurality of linear concave grooves extending in the axial direction with a certain interval in the circumferential direction, and multiple spiral concave grooves extending in the circumferential direction and the axial direction can be mentioned. In addition, a plurality of annular grooves extending in the circumferential direction with a constant interval in the axial direction, a plurality of concave grooves intersecting in a lattice shape or a lattice shape, a herringbone-shaped concave groove in the axial direction and The thing arrange | positioned equally about the circumferential direction is also mentioned. Moreover, as a hollow, what arrange | positioned the hemispherical hollow in the grid | lattice form about the axial direction and the circumferential direction is mentioned.

  Furthermore, in the above-described glow plug, the recess may be a glow plug including a plurality of linear concave grooves extending in at least the axial direction in the axial direction and a circumferential direction around the axial line.

  In this glow plug, the concave portion includes a plurality of linear grooves extending in at least the axial direction of the axial direction and the circumferential direction. By providing such a concave groove, the lubricant retained in the concave groove moves in the axial direction, which is the direction of the press-fitting, during the press-fitting, and the lubricant is present at the interface between the housing and the outer cylinder. Supplied to relieve friction during press fitting. As a result, the outer cylinder can be pressed more smoothly, can be properly pressed, and a more reliable glow plug can be obtained.

  Furthermore, in the above-described glow plug, the concave groove may be a glow plug having a linear shape extending in the axial direction.

  In this glow plug, since the concave groove has a linear shape extending in the axial direction, in addition to smooth press-fitting of the outer cylinder, the concave groove can be easily formed.

  Furthermore, in any one of the glow plugs described above, the length L1 in the axial direction of the recess forming region is 30% or more of the length L in the axial direction of the pressure contact surface, and the recess non-forming region The length L2 in the axial direction is preferably a glow plug of 2 mm or more.

In this glow plug, the length L1 in the axial direction of the recess forming region is 30% or more of the length L in the axial direction of the pressure contact surface. Thereby, the length of the recessed part formation area which can hold | maintain a lubricant is ensured, and the biting at the time of press injection can be prevented appropriately.
On the other hand, the length L2 in the axial direction of the non-recessed region is 2 mm or more. As a result, the length of the non-recessed region can be secured and the shaft hole of the housing and the outer cylinder can be reliably hermetically sealed.

  Further, in any one of the glow plugs described above, the recess forming region may be a glow plug in which the recesses are uniformly arranged in at least one of the axial direction and a circumferential direction around the axial line.

  In this glow plug, in the recessed portion forming region, the recessed portions are equally arranged in at least one of the axial direction and the circumferential direction around the axial line. Specifically, for example, concave grooves arranged at regular intervals in the circumferential direction or the axial direction, lattice-shaped or grid-shaped concave grooves or hemispherical depressions are equally distributed in the axial direction and the circumferential direction. The one arranged is mentioned. As a result, the outer cylinder can be uniformly press-fitted, and the surface pressure stress distribution between the housing and the outer cylinder after the press-fitting can be suppressed from causing partial imbalance in the axial direction or the circumferential direction. For this reason, it becomes a more reliable glow plug.

  Furthermore, any one of the above-described glow plugs may be a glow plug having the concave portion forming region and the concave portion non-forming region on the outer peripheral pressure contact surface of the outer cylinder.

  In this glow plug, the outer peripheral pressure contact surface of the outer cylinder has a concave portion formation region and a concave portion non-formation region. Compared to the case where these are formed on the inner peripheral pressure contact surface of the shaft hole of the housing, the concave portion can be easily recessed. Can be formed.

  In this glow plug, since the concave portion non-forming region is located on the distal end side in the axial direction of the concave portion forming region on the outer peripheral pressure contact surface of the outer cylinder, the shaft hole can be appropriately sealed on the distal end side in the axial direction of the housing. Moreover, it can also prevent appropriately that a foreign material penetrate | invades into the inside of a housing by this.

  Furthermore, in any one of the glow plugs described above, the heater may be a glow plug that is a ceramic heater.

In the ceramic glow plug, since the outer cylinder into which the hard ceramic heater is press-fitted is press-fitted into the housing, the outer cylinder is not easily deformed (reduced in diameter) during press-fitting, and galling is likely to occur compared to the metal glow plug.
However, in this glow plug, since the concave portion is formed on at least one of the press contact surfaces, it is possible to prevent the occurrence of galling at the time of press-fitting and to ensure that the outer cylinder is properly press-fitted while being a ceramic glow plug. High ceramic glow plug.

In another aspect, the heater has a cylindrical shape with a heater that generates heat when energized and a cylindrical hole that passes through in the axial direction along the axis of the heater. an outer cylinder formed by holding a has a shaft hole that extends in the axial direction, in the axial hole, and press fitting the outer cylinder from its front end side, the inner peripheral surface of the shaft hole is pressing surface A housing in which the inner peripheral pressure contact surface and the outer peripheral pressure contact surface of the outer peripheral surface of the outer cylinder are pressed against each other and the heater is held via the outer cylinder, and a glow plug manufacturing method comprising: At least one of the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the shaft hole is a recess forming region in which a recess for holding a lubricant that relaxes friction during the press-fitting is formed in the axial direction. And the concave portion is not formed, the pressure contact surface of the other party Coherent, anda recess non-formation region to seal hermetically the shaft hole of the housing in the outer tube, when the outer peripheral pressing surface of the outer cylinder having the recess formed region and the recess-free region is Of the outer peripheral pressure contact surface of the outer cylinder, the rear end side in the axial direction with respect to the concave portion non-formation region is all the concave portion formation region, and the inner peripheral pressure contact surface of the shaft hole of the housing is the concave portion formation. When the region and the concave portion non-forming region are included, all of the inner circumferential pressure contact surface of the shaft hole is set as the concave portion forming region in the axial direction tip side from the concave portion non-forming region. A glow plug manufacturing method including an outer cylinder press-fitting step of press-fitting the outer cylinder holding the heater into the shaft hole of the housing while holding the lubricant in the recess.

This glow plug manufacturing method includes an outer cylinder press-fitting process in which an outer cylinder holding a heater in a cylinder hole is press-fitted into a shaft hole of a housing while retaining a lubricant that reduces friction in a recess.
At least one of the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the housing includes a recessed portion forming region and a recessed portion non-formed region in the axial direction.
For this reason, at the time of press-fitting, since the lubricant is supplied from the recess to the housing and the outer cylinder, friction during press-fitting is relieved. As a result, the occurrence of galling during press-fitting can be prevented, and a highly reliable glow plug can be manufactured with high yield.
In addition, since the press-fitting load can be reduced, the glow plug can be manufactured by reducing the press-fitting equipment to reduce the manufacturing cost.
On the other hand, the concave portion non-forming region is in close contact with the other pressure contact surface, and the shaft hole of the housing can be hermetically sealed. Thereby, it is possible to prevent foreign matter from entering the housing through the recess from the front end of the housing.

  Furthermore, in the above-described method for manufacturing a glow plug, an application step of applying the lubricant to at least the recess forming region of the outer peripheral surface of the outer cylinder and the inner peripheral surface of the shaft hole of the housing. A method for manufacturing a glow plug is preferable.

  Since this glow plug manufacturing method includes an application step, it is possible to press-fit in the outer cylinder press-fitting step after the lubricant is reliably held in the recess.

It is a longitudinal cross-sectional view of the glow plug which concerns on embodiment. It is the longitudinal cross-sectional view which expanded the front-end | tip part containing a ceramic heater and an outer cylinder among the glow plugs which concern on embodiment. It is a perspective view of the outer cylinder used for the glow plug which concerns on embodiment. It is a fragmentary sectional view which shows the press-fit state of an outer cylinder about the site | part of the front end side of the glow plug which concerns on embodiment. It is a perspective view of the outer cylinder used for the glow plug concerning modification 1. It is a fragmentary sectional view which shows the press-fit state of an outer cylinder about the site | part of the tip side of the glow plug which concerns on the deformation | transformation forms 1-6. It is a fragmentary sectional view which shows the site | part of the front end side of the metal shell used for the glow plug which concerns on the deformation | transformation form 7 and the reference form 1 . It is a perspective view which shows the case where a recessed part non-formation area | region is provided in the axial direction rear end side of an outer cylinder, and a recessed part formation area is provided in the front end side. It is a longitudinal cross-sectional view which shows the case where the form of an outer cylinder is formed in 2 steps | paragraphs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall structure of the glow plug 100 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal sectional view of the entire glow plug 100. FIG. 2 is an enlarged longitudinal sectional view of the tip portion of the glow plug 100 including the ceramic heater 130 and the outer cylinder 150. 1 and 2, the side (lower side in the figure) on which the ceramic heater 130 is disposed in the axial direction HJ along the axis AX of the glow plug 100 is defined as the tip side GS, and the opposite side (in the figure) The upper side) will be described as the rear end side GK.

  The glow plug 100 is attached to a fuel chamber of a diesel engine, for example, and is used as a heat source that assists ignition when starting the engine. The glow plug 100 includes a metal shell 110 as a housing, a center shaft 120, a ceramic heater 130 (heater), a ring member 140, an outer cylinder 150, a pin terminal 160, and the like.

Of these, the metal shell 110 is made of an iron-based material equivalent to S45C, and has a cylindrical shape extending in the axial direction HJ from the metal base end 110k to the metal tip 110s. A shaft hole 110 h is formed in the metal shell 110. Further, a male screw portion 111 for attachment is formed on the outer peripheral surface 110 m of the metal shell 110.
In addition, a tool engagement portion 113 is formed on the outer side of the metal base end portion 110k of the metal shell 110 so that the outer peripheral surface has a hexagonal column shape and the attachment tool engages. On the other hand, a taper portion 115 that expands the diameter of the shaft hole 110h toward the rear end side GK is formed inside the metal base end portion 110k, and the base end portion of the shaft hole 110h is a large diameter hole 110hk. Yes.

  The middle shaft 120 is made of an iron-based material such as stainless steel and has a rod shape extending in the axial direction HJ from the middle shaft base end portion 120k to the middle shaft front end portion 120s. The central shaft base end portion 120k is inserted into the metal shell 110 in a state of projecting from the metal base end portion 110k toward the rear end side GK. Further, the central shaft front end portion 120s is fitted in a ring base end portion 140k of a ring member 140 described later.

  The ceramic heater 130 has a rod shape extending in the axial direction HJ from the heater base end portion 130k to the heater front end portion 130s, and the heater front end portion 130s that generates heat when energized is projected from the metal fitting front end portion 110s toward the front end side GS. In the state, it is inserted into the metallic shell 110. This ceramic heater 130 includes a conductive ceramic (specifically, silicon nitride containing tungsten carbide as a conductive component) inside a rod-shaped insulating base 131 made of an insulating ceramic (specifically, a silicon nitride ceramic). The heating resistor 132 made of a ceramic is embedded.

  The heating resistor 132 includes a heating part 133 and a pair of lead parts 135 and 136. Of these, the heat generating portion 133 has a U-shaped bent shape and is disposed in the heater front end portion 130s. A pair of lead portions 135 and 136 are connected to both ends of the heat generating portion 133 bent back in the U-shape, and extend to the base end surface 130 km of the ceramic heater 130 and exposed to the base end surface 130 km. In addition, electrode lead portions 137 and 138 that form terminals of the ceramic heater 130 are formed in the respective lead portions 135 and 136. That is, the lead portion 135 is formed with an electrode extraction portion 137 at the heater base end portion 130k, exposed to the outer periphery of the heater base end portion 130k, and electrically connected to the ring member 140 described below. Further, the lead portion 136 is formed with an electrode extraction portion 138 on the front end side GS from the heater base end portion 130k, and is exposed to the outer periphery of the ceramic heater 130 and connected to an outer cylinder 150 described later.

  The ring member 140 is made of stainless steel and has a cylindrical shape extending in the axial direction HJ from the ring base end portion 140k to the ring front end portion 140s. And it arrange | positions in the metal shell 110 and connects between the center axis | shaft 120 and the ceramic heater 130. FIG.

The heater base end portion 130k of the ceramic heater 130 is press-fitted into the ring front end portion 140s of the ring member 140, and the electrode extraction portion 137 provided in the ceramic heater 130 comes into contact with the ring member 140 from the inside. Electrically connected.
On the other hand, the middle shaft front end portion 120s of the middle shaft 120 is press-fitted into the ring base end portion 140k of the ring member 140, and the ring member 140 and the middle shaft 120 are electrically connected. Further, the ring member 140 and the middle shaft 120 are fixed to each other by a welded portion 149 formed between the ring base end portion 140k and the middle shaft front end portion 120s.

  The outer cylinder 150 is made of stainless steel and has a cylindrical shape extending in the axial direction HJ from the outer cylinder base end 150k to the outer cylinder distal end 150s. In the outer cylinder 150, the heater front end portion 130s protrudes from the outer cylinder front end portion 150s toward the front end side GS, and the heater base end portion 130k protrudes from the outer cylinder base end portion 150k toward the rear end side GK. A ceramic heater 130 is press-fitted into the form. The electrode extraction portion 138 provided in the ceramic heater 130 is in contact with the outer cylinder 150 from the inside and is electrically connected to the outer cylinder 150.

  Further, the outer cylinder base end portion 150k of the outer cylinder 150 is press-fitted into the shaft hole 110h of the metal shell 110 from the distal end GS of the metal shell 110, and by this press-fitting, the inner periphery of the inner peripheral surface 110hm of the shaft hole 110h. The pressure contact surface 110fm and the outer peripheral pressure contact surface 150fm of the outer peripheral surface 150m of the outer cylinder 150 are in pressure contact with each other. As a result, the ceramic heater 130 is held via the outer cylinder 150 at the metal fitting tip 110 s on the tip side GS of the metal shell 110.

  The pin terminal 160 is fixed to the middle shaft base end portion 120k of the middle shaft 120 by circumferential caulking. The pin terminal 160 is connected with a cord for supplying power from an external power source (not shown). Further, an O-ring 161 and a cylindrical insulating spacer 163 are disposed on the distal end GS of the pin terminal 160. Specifically, the O-ring 161 and the insulating spacer 163 are arranged between the middle shaft 120 in the metal base end portion 110k (the large diameter hole 110hk of the shaft hole 110h) of the metal shell 110, and insulate them from each other. doing.

  Next, the outer cylinder 150 will be described in more detail with reference to FIGS. 3 and 4. As described above, the outer cylinder 150 has a cylindrical shape extending from the outer cylinder base end portion 150k to the outer cylinder front end portion 150s, and the outer cylinder base end portion 150k is press-fitted into the shaft hole 110h of the metal shell 110, and the shaft The inner circumferential pressure contact surface 110fm of the hole 110h and the outer circumferential pressure contact surface 150fm of the outer cylinder 150 are in pressure contact with each other. In FIG. 4, the outer peripheral pressure contact surface 150 fm is a portion of the outer peripheral surface 150 m of the outer cylinder 150 that is located in the shaft hole 110 h of the metal shell 110, and the length in the axial direction HJ is L. Further, the inner circumferential pressure contact surface 110fm is a part of the inner circumferential surface 110hm of the shaft hole 110h of the metal shell 110 that becomes the other pressure contact surface of the outer circumferential pressure contact surface 150fm, and the length in the axial direction HJ is L. .

  The outer circumferential pressure contact surface 150fm of the outer cylinder 150 has a plurality of linear concave grooves 151g extending in the axial direction HJ and arranged at a constant interval in the circumferential direction HR around the axis AX. (See FIG. 3). The concave groove 151g is a concave portion 151 that holds a lubricant such as lubricating oil that reduces friction when the outer cylinder 150 is press-fitted into the shaft hole 110h of the metal shell 110. As a result, the friction is reduced by the lubricant held in the concave groove 151g (the concave portion 151), and the occurrence of galling during press-fitting is prevented, so that the outer cylinder 150 is appropriately placed in the shaft hole 110h of the metal shell 110. Can be press-fitted.

  Further, as shown in FIG. 4, the outer peripheral pressure contact surface 150fm of the outer cylinder 150 has a recess forming region 150f1 (a portion having the length in the axial direction HJ of L1) in which the recessed groove 151g (recessed portion 151) is formed, and its axis line. In the direction HJ front end side GS, there is a recessed portion non-formed region 150f2 (a portion where the length in the axial direction HJ is L2) where the recessed portion 151 is not formed. And in this recessed part non-formation area | region 150f2, it is closely_contact | adhered to the inner peripheral press contact surface 110fm of the shaft hole 110h which is a counterpart press contact surface.

For example, the recessed portion forming region 150f1 in which the recessed groove 151g (recessed portion 151) is formed occupies the entire outer peripheral pressure contact surface 150fm, and the recessed groove 151g is more axial than the tip 110ss of the metal shell 110 into which the outer cylinder 150 is press-fitted. When extending to the range of the direction HJ tip side GS, foreign matter around the glow plug 100 such as oil may enter the glow plug 100 from the tip 110ss of the metal shell 110 through the concave groove 151g.
However, in this glow plug 100, the outer peripheral pressure contact surface 150fm has the concave portion non-forming region 150f2 at the tip end GS in the axial direction HJ of the concave portion forming region 150f1, as described above, and the shaft is formed in the concave portion non-forming region 150f2. The hole 110h is in close contact with the inner circumferential pressure contact surface 110fm. Thereby, the shaft hole 110h of the metal shell 110 can be hermetically sealed with the outer cylinder 150. In addition, foreign matter around the glow plug 100 can be prevented from entering the glow plug 100 through the concave groove 151g from the tip 110ss of the metal shell 110.

From the viewpoint of preventing galling, the length L1 in the axial direction HJ of the recess forming region 150f1 is preferably 30% or more of the length L in the axial direction HJ of the outer peripheral pressure contact surface 150fm. In the present embodiment, in the outer circumferential pressure contact surface 150fm, the rear end side GK in the axial direction HJ from the recess non-forming region 150f2 is all set as the recess forming region 150f1, and the length L1 is about 85% of the length L.
In order to hermetically seal the shaft hole 110h of the metal shell 110, the length L2 in the axial direction HJ of the recess-unformed region 150f2 is preferably 2 mm or more. In the present embodiment, the length L2 of 2.5 mm or more is secured by setting the axial direction HJ front end side GS of the outer circumferential pressure contact surface 150fm as the recess non-forming region 150f2.

  Further, as described above, the concave groove 151g extends in the axial direction HJ. Therefore, when the outer cylinder 150 is press-fitted into the metal shell 110, the concave groove 151g is inserted in the axial direction HJ that is the press-fitting direction. The lubricant moves and easily holds the lubricant. Thereby, the outer cylinder 150 can be press-fitted more smoothly.

Further, the concave grooves 151g extend linearly in the axial direction HJ, and are evenly arranged with a constant interval in the circumferential direction HR around the axial line AX. For this reason, the stress distribution of the surface pressure between the metal shell 110 and the outer cylinder 150 after press-fitting is made more uniform by suppressing partial imbalances in the axial direction HJ and the circumferential direction HR. be able to.
As described above, a more reliable glow plug 100 can be obtained.

  In the glow plug 100 of the present embodiment, the ceramic heater 130 corresponds to the “heater” in the present invention, and the metal shell 110 corresponds to the “housing” in the present invention.

As described above, in the glow plug 100 of the present embodiment, the outer circumferential pressure contact surface 150fm of the outer cylinder 150 reduces friction when the outer cylinder 150 is press-fitted into the shaft hole 110h of the metal shell 110 (housing). It includes a recess forming region 150f1 in which a recess 151 (recess groove 151g) for holding the lubricant is formed.
As a result, the friction is alleviated by the lubricant held in the concave portion 151 (the concave groove 151g), the occurrence of galling can be prevented, and appropriate press-fitting can be performed, so that the metal shell 110 and the outer cylinder 150 after press-fitting can be performed. Therefore, the outer plug 150 and the ceramic heater 130 are hardly cracked, and the glow plug 100 is highly reliable.
On the other hand, the outer peripheral pressure contact surface 150fm including the recess formation region 150f1 also has a recess non-formation region 150f2 in which the recess 151 is not formed on the front end GS in the axial direction HJ of the recess formation region 150f1. The non-forming region 150f2 is in close contact with the inner circumferential pressure contact surface 110fm of the shaft hole 110h, and the shaft hole 110h of the metal shell 110 can be hermetically sealed with the outer cylinder 150. This also prevents foreign matter from entering the metal shell 110 from the tip 110ss of the metal shell 110 through the recess 151 (the groove 151g).

Further, in the glow plug 100 of the present embodiment, the concave portion 151 is a plurality of linear concave grooves 151g extending in the axial direction HJ. By providing such a concave groove 151g, the lubricant retained in the concave groove 151g moves in the axial direction HJ, which is the direction of the press-fitting, during the press-fitting, and between the metal shell 110 and the outer cylinder 150. Lubricant is supplied to the interface, and friction during press-fitting is relieved. As a result, the press-fitting of the outer cylinder 150 becomes smoother, the press-fitting can be performed properly, and a more reliable glow plug is obtained.
Moreover, since the concave groove 151g has a linear shape extending in the axial direction HJ, in addition to smooth press-fitting of the outer cylinder 150, it is easy to form the concave groove.

In the glow plug 100 of the present embodiment, the length L1 in the axial direction HJ of the recess forming region 150f1 is 30% or more of the length L in the axial direction HJ of the outer circumferential pressure contact surface 150fm (in the present embodiment, approximately 85%). ). Thereby, the length of the recessed portion forming region 150f1 that can hold the lubricant can be secured, and the galling at the time of press-fitting can be appropriately prevented.
On the other hand, the length L2 in the axial direction HJ of the recess-free region 150f2 is 2 mm or more (in this embodiment, 2.5 mm or more is ensured). Accordingly, the length of the recess non-forming region 150f2 can be secured, and the shaft hole 110h and the outer cylinder 150 of the metal shell 110 can be reliably hermetically sealed.

  Further, in the glow plug 100 of the present embodiment, the concave grooves 151g extend linearly in the axial direction HJ, and are evenly arranged in the concave portion forming region 150f1 with a constant interval in the circumferential direction HR. As a result, the outer cylinder 150 can be uniformly press-fitted, and the surface pressure stress distribution between the metal shell 110 and the outer cylinder 150 after the press-fitting also causes a partial imbalance in the axial direction HJ or the circumferential direction HR. Can be suppressed. For this reason, the glow plug 100 is further reliable.

  In addition, the glow plug 100 of the present embodiment has a recessed portion forming region 150f1 and a recessed portion non-formed region 150f2 on the outer peripheral pressure contact surface 150fm of the outer cylinder 150, and these are connected to the inner peripheral pressure contact of the shaft hole 110h of the metal shell 110. Compared to the case where the surface 110fm is formed, the concave portion 151 (the concave groove 151g) can be easily formed.

  Further, in the glow plug 100 of the present embodiment, the concave portion non-forming region 150f2 is located on the distal end side GS in the axial direction HJ of the concave portion forming region 150f1 on the outer circumferential pressure contact surface 150fm of the outer cylinder 150. The axial hole 110h can be appropriately sealed by the axial direction HJ front end side GS. Moreover, it can also prevent appropriately that a foreign material penetrate | invades into the metal shell 110 inside.

In the ceramic glow plug, the outer cylinder 150 is not easily deformed (reduced in diameter) at the time of press-fitting, and therefore, galling is likely to occur compared to the metal glow plug.
However, in the glow plug 100 of the present embodiment, since the concave portion 151 (the concave groove 151g) is formed on the outer peripheral pressure contact surface 150fm of the outer cylinder 150, the occurrence of galling during press-fitting is prevented even though it is a ceramic glow plug. Thus, a highly reliable ceramic glow plug in which the outer cylinder 150 is appropriately press-fitted is obtained.

Next, a method for manufacturing the glow plug 100 will be described.
First, a ceramic heater 130 having a round bar shape and a hemispherical heater tip 130s is obtained by a known method.

  Next, a ring member 140 in which a stainless steel material is formed in a cylindrical shape is prepared, and Au plating is applied to the surface thereof. Then, the heater base end portion 130k of the ceramic heater 130 is press-fitted into the ring member 140, and the ring member 140 and the electrode extraction portion 137 of the ceramic heater 130 are electrically connected.

Further, the outer cylinder 150 is obtained by forming a stainless steel plate into a cylindrical shape by deep drawing and cutting the plate. Further, by this deep drawing, a plurality of linear grooves 151g (recesses) extending in the axial direction HJ to the outer circumferential pressure contact surface 150fm of the outer circumferential surface 150m of the outer cylinder 150 and forming a constant interval in the circumferential direction HR. 151) at the same time. The outer cylinder 150 may be formed by cutting a stainless steel pipe material into a predetermined dimension, and the concave groove 151g (recess 151) is obtained by cutting, rolling, or the like after obtaining the outer cylinder 150. It may be formed separately.
Thereafter, the ceramic heater 130 is press-fitted into the cylindrical hole 150h of the outer cylinder 150, and the outer cylinder 150 and the electrode extraction portion 138 are electrically connected. Thereby, the ceramic heater 130, the ring member 140, and the outer cylinder 150 are united, and the ceramic heater 130 is hold | maintained at the outer cylinder 150. FIG.

  Furthermore, a central shaft 120 in which an iron-based material (for example, Fe—Cr—Mo steel) is formed in a rod shape is prepared, and the central shaft front end portion 120 s of the central shaft 120 is press-fitted into the ring member 140, and the alignment site is laser Welding is performed (welded portion 149). As a result, the middle shaft 120, the ceramic heater 130, and the outer cylinder 150 holding the ceramic heater 130 are integrally coupled via the ring member 140.

  Next, a metal shell 110 in which an iron-based material such as S45C is formed in a cylindrical shape is prepared. Then, a screw thread is rolled on the outer peripheral surface 110 m to form a male screw portion 111. Further, by a cutting process or the like, a tapered portion 115 that is tapered toward the rear end side GK in the axial direction HJ is formed in the opening portion of the shaft hole 110h in the metal base end portion 110k of the metal shell 110.

Thereafter, a lubricant is applied to the recess forming region 150f1 of the outer peripheral surface 150m of the outer cylinder 150 (application process), and the outer cylinder base end 150k of the outer cylinder 150 is press-fitted into the shaft hole 110h of the metal shell 110 ( Outer cylinder press-fitting process). At this time, the lubricant applied to the recessed portion forming region 150f1 of the outer cylinder 150 is held in the recessed groove 151g (recessed portion 151), and the retained lubricant is held between the outer cylinder base end portion 150k of the outer cylinder 150 and the metal shell 110. Since it is supplied to the interface with the shaft hole 110h, friction during press-fitting is relieved and galling is less likely to occur. In the application step, the lubricant is not only the recess forming region 150f1 of the outer peripheral surface 150m of the outer cylinder 150, but also the portion that becomes the outer peripheral pressure contact surface 150fm including the recess non-forming region 150f2, and the shaft hole of the metal shell 110. You may apply | coat to the site | part used as the inner peripheral press-contact surface 110fm of 110h inner peripheral surface 110hm.
As a result, the outer cylinder base end portion 150k of the outer cylinder 150 is press-fitted into the shaft hole 110h of the metal shell 110, and the middle shaft 120 is inserted into the metal metal tip 110s of the metal shell 110 via the outer cylinder 150. And the ceramic heater 130 integrated with each other is held. Further, the middle shaft base end portion 120k of the middle shaft 120 protrudes from the metal fitting base end portion 110k of the metal shell 110 toward the rear end side GK.

Thereafter, from the rear end side GK of the metal shell 110, the O-ring 161 and the insulating spacer 163 are externally fitted to the middle shaft base end portion 120k of the middle shaft 120, and the O-ring 161 and the insulating spacer 163 are fitted to the metal base end of the metal shell 110. It arrange | positions in the part 110k (large diameter hole 110hk of the shaft hole 110h). Then, the pin terminal 160 is fitted into the central shaft base end portion 120k, the insulating spacer 163 is pressed against the distal end side GS, and the pin terminal 160 is crimped radially inward.
Thus, the glow plug 100 is completed.

As described above, in the method for manufacturing the glow plug 100 according to the present embodiment, the outer cylinder 150 holding the ceramic heater 130 in the cylinder hole 150h is inserted into the recess 151 in the shaft hole 110h of the metal shell 110 (housing). An outer cylinder press-fitting step of press-fitting while retaining a lubricant that reduces friction in the (concave groove 151g) is provided.
The outer peripheral pressure contact surface 150fm of the outer cylinder 150 is not formed with the concave portion forming region 150f1 in which the concave portion 151 (the concave groove 151g) for holding the lubricant is formed and the concave portion 151 in the axial direction HJ. 110 includes a non-recessed region 150 f 2 that is in close contact with the inner circumferential pressure contact surface 110 fm of the 110 shaft hole 110 h and hermetically seals the shaft hole 110 h of the metal shell 110 with the outer cylinder 150.
For this reason, the lubricant is held in the concave portion 151 (the concave groove 151g) during the press-fitting, and the lubricant is supplied from the concave portion 151 between the metal shell 110 and the outer cylinder 150. Is alleviated. Thereby, the occurrence of galling during press-fitting can be prevented, and the highly reliable glow plug 100 can be manufactured with high yield.
In addition, since the press-fit load can be reduced, the glow plug 100 can be manufactured with a small press-fit facility and reduced manufacturing costs.
On the other hand, the recess-free region 150f2 is in close contact with the inner circumferential pressure contact surface 110fm of the shaft hole 110h, and the shaft hole 110h of the metal shell 110 can be hermetically sealed with the outer cylinder 150. Thereby, it is possible to prevent foreign matter from entering the metal shell 110 from the tip 110ss of the metal shell 110 through the recess 151 (the groove 151g).

  Furthermore, since the manufacturing method of the glow plug 100 of the present embodiment includes an application step of applying a lubricant to the recess formation region 150f1, the lubricant is securely held in the recess 151 (the recess groove 151g). In the outer cylinder press-fitting step, press-fitting can be performed.

(Deformation)
Next, a modification of the above-described embodiment will be described with reference to FIGS. In the above-described embodiment, as shown in FIGS. 3 and 4, as the recess 151, a plurality of straight lines extending in the axial direction HJ on the outer circumferential pressure contact surface 150 fm and equally arranged in the circumferential direction HR around the axis AX. The outer cylinder 150 provided with a concave groove 151g was used.
On the other hand, in the first modified embodiment (modified embodiment 1) shown in FIG. 5 and FIG. 6A, the concave portion 251 is a multiple spiral concave portion extending in the circumferential direction HR and the axial direction HJ on the outer circumferential pressure contact surface 250fm. An outer cylinder 250 having a groove 251g is used.
Such a multi-helical concave groove 251g is also equally arranged in the concave portion formation region 250f1 in the axial direction HJ and the circumferential direction HR. For this reason, when the outer cylinder 250 is press-fitted into the metal shell 110, the lubricant held in the groove 251g moves in the axial direction HJ, which is the direction of the press-fitting, between the outer cylinder 250 and the metal shell 110. Lubricant is supplied to the interface, and friction during press-fitting is relieved. Further, the stress distribution of the surface pressure between the metal shell 110 and the outer cylinder 250 after press-fitting can be made uniform by suppressing partial imbalance in the axial direction HJ and the circumferential direction HR. it can. Therefore, the same effect as the embodiment can be obtained, and the glow plug 100 with high reliability can be obtained.
In addition, it is the same as the embodiment in that the recess 251 is not formed in the axial direction HJ front end side GS of the recess forming area 250f1, and the axis of the metallic shell 110 is the same as the embodiment. The hole 110h can be hermetically sealed.

In addition, as a recessed part, it is good also as a form shown to FIG.6 (b)-(f) other than this modification 1 (modification 2-6).
In the second modification shown in FIG. 6B, as the concave portion 351, a plurality of annular concave grooves that are arranged at regular intervals in the axial direction HJ and extend in the circumferential direction HR are provided.

Moreover, in the modification 3 shown in FIG.6 (c), as the recessed part 451, what the groove | channel extended in the axial direction HJ and the annular groove | channel extended in the circumferential direction HR cross | intersected in the grid | lattice form is provided.
Further, the concave grooves 551 (deformation 4) intersecting in the shape of a circle in FIG. 6 (d) and the herringbone-shaped concave grooves 651 (deformation 5) in FIG. 6 (e) are arranged in the axial direction HJ and the circumferential direction HR. May be provided evenly.
Moreover, you may arrange | position the hemispherical hollow 751 of FIG.6 (f) at the grid | lattice form about the axial direction HJ and the circumferential direction HR (modification 6).
In these modified embodiments 1 to 6, as in the embodiment, the friction is alleviated by the lubricant held in the recesses, the occurrence of galling can be prevented, the press-fitting can be performed appropriately, and a reliable glow Plug 100 is formed.

  Further, in the embodiment, an example in which the recessed portion forming region 150f1 and the recessed portion non-forming region 150f2 are provided on the outer peripheral pressure contact surface 150fm of the outer cylinder 150 is shown, and the first to sixth modified embodiments are similar to this. As shown in FIGS. 7A and 7B, the inner peripheral pressure contact surfaces 210fm and 310fm of the shaft holes 210h and 310h of the metal shells 210 and 310 are formed in the recess forming regions 210f1 and 310f1 and the recess non-forming regions 210f2 and 310f2. May be provided (variants 7 and 8).

Here, in the modified embodiment 7 of FIG. 7A, the recess non-forming region 210f2 is provided closer to the rear end side GK in the axial direction HJ than the recess forming region 210f1, and this is more preferable from the viewpoint of preventing galling. . On the other hand, in the reference form 1 of FIG. 7B, the recess non-forming region 310f2 is provided in the axial direction HJ tip side GS from the recess forming region 310f1, and the shaft hole 310h of the metal shell 310 is hermetically sealed. From the viewpoint of doing this, this is more preferable.
On the other hand, when the recessed portion forming region 150f1 and the recessed portion non-formed region 150f2 of the embodiment (and modified embodiments 1 to 6) are provided on the outer peripheral pressure contact surface 150fm of the outer cylinder 150, from the viewpoint of both anti-galling and hermetic sealing. The recess non-forming region 150f2 is preferably provided closer to the front end GS in the axial direction HJ than the recess forming region 150f1.

Further, the recessed portion forming region and the recessed portion non-forming region may be provided on both the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the shaft hole of the metal shell. The arrangement in the axial direction HJ is adapted to each other between the outer peripheral pressure contact surface and the inner peripheral pressure contact surface.
For example, when the inner peripheral pressure contact surface of the metal shell has the same form as the modified embodiment 7 shown in FIG. 7A, the outer peripheral pressure contact surface 850fm of the outer peripheral surface 850m of the outer cylinder 850 is shown in FIG. Among them, a recess non-formation region 850f2 is provided on the rear end side GK in the axial direction HJ, and a recess formation region 850f1 is provided on the tip side GS thereof.

In the above, the present invention has been described with reference to the embodiments and modified embodiments. However, the present invention is not limited to the above-described embodiments and modified embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say, it can be done.
For example, in the embodiment, a so-called ceramic glow plug provided with the ceramic heater 130 is illustrated as the glow plug 100, but the present invention is not limited to this, and a heater that houses a heating coil or a heating coil and a control coil in a metal sheath. You may apply to what is called a metal glow plug provided with.
Further, in the embodiment, the case where the outer cylinder 150 is formed into a cylindrical shape by deep drawing or cutting a pipe material is shown, but the form of the outer cylinder 150 is not limited to this, for example, as shown in FIG. As described above, the outer cylinder distal end portion 150s of the outer cylinder 150 may be formed in a two-stage shape whose diameter is smaller than that of the outer cylinder base end portion 150k by cutting or the like.

AX Axis line HJ Axial direction GS Front end side GK Rear end side HR Circumferential direction 100 Glow plug 110, 210, 310 Metal shell (housing)
110h, 210h, 310h Shaft hole 110hm (shaft hole) inner peripheral surface 110fm, 210fm, 310fm Inner peripheral pressure contact surface 210f1, 310f1 Recess formation area 210f2, 310f2 Recess non-formation area 120 Middle shaft 130 Ceramic heater (heater)
137,138 Electrode extraction part 140 Ring member 150 Outer cylinder 150h Outer cylinder surface 150m, 250m, 850m Outer peripheral surface 150fm, 250fm, 850fm Outer peripheral pressure contact surface 150f1, 250f1, 850f1 Recess formation area 150f2, 250f1, 850f1 Recess non Formation area 151,251,351,451,551,651,751 Recessed part 151g, 251g Recessed groove (recessed part)

Claims (9)

A heater that generates heat when energized;
An outer cylinder that has a cylindrical hole that penetrates in the axial direction along its own axis, and that holds the heater in the cylindrical hole in a state where the tip of the heater protrudes;
An axial hole extending in the axial direction; the outer cylinder is press-fitted into the axial hole from the tip side of the axial hole; an inner peripheral pressure contact surface of the inner peripheral surface of the shaft hole which is a pressure contact surface; A housing formed by pressing the outer peripheral pressure contact surfaces of the outer peripheral surface with each other and holding the heater via the outer cylinder;
At least one of the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the shaft hole is in the axial direction.
A recessed portion forming region in which a recessed portion for holding a lubricant that relaxes friction during the press-fitting is formed;
Not the recess is formed in close contact with the contact face of the counterpart, viewed contains and a recess-free region which hermetically seals the shaft hole of the housing in the outer tube,
When the outer peripheral pressure contact surface of the outer cylinder has the concave portion forming region and the concave portion non-forming region, the axial rear end side of the outer peripheral pressure contact surface of the outer tube is more than the concave portion non-forming region. The recess formation region,
When the inner circumferential pressure contact surface of the shaft hole of the housing has the recessed portion forming region and the recessed portion non-formed region, the tip end in the axial direction of the inner peripheral pressure contacting surface of the shaft hole is more axial than the recessed portion non-formed region. A glow plug in which all the sides are used as the recess forming region . The glow plug according to claim 1,
The recess is
A glow plug including a plurality of linear grooves extending in at least the axial direction of the axial direction and a circumferential direction around the axial line. The glow plug according to claim 2,
The concave groove is a glow plug having a linear shape extending in the axial direction. The glow plug according to any one of claims 1 to 3, wherein
The axial length L1 of the recess forming region is 30% or more of the axial length L of the pressure contact surface,
A glow plug having a length L2 in the axial direction of the recess-unformed region of 2 mm or more. The glow plug according to any one of claims 1 to 4, wherein
The recess forming region is a glow plug in which the recesses are uniformly arranged in at least one of the axial direction and a circumferential direction around the axial line. The glow plug according to any one of claims 1 to 5,
A glow plug having the recess forming region and the recess non-forming region on the outer peripheral pressure contact surface of the outer cylinder. The glow plug according to any one of claims 1 to 6 ,
The heater is a glow plug which is a ceramic heater. A heater that generates heat when energized;
An outer cylinder that has a cylindrical hole that penetrates in the axial direction along its own axis, and that holds the heater in the cylindrical hole in a state where the tip of the heater protrudes;
Has a shaft hole extending in the axial direction, in the axial hole, and press fitting the outer cylinder from its front end side, the inner peripheral pressing surface of the inner peripheral surface of the shaft hole is a contact face and the outer tube And a housing formed by holding the heater via the outer cylinder, the outer peripheral pressure contact surface of the outer peripheral surface of each other, and a manufacturing method of a glow plug comprising:
At least one of the outer peripheral pressure contact surface of the outer cylinder and the inner peripheral pressure contact surface of the shaft hole is a recess forming region in which a recess for holding a lubricant that relaxes friction during the press-fitting is formed in the axial direction. And the concave portion is not formed, is in close contact with the pressure contact surface of the other party, and includes a concave portion non-formation region that hermetically seals the shaft hole of the housing with the outer cylinder,
When the outer peripheral pressure contact surface of the outer cylinder has the concave portion forming region and the concave portion non-forming region, the axial rear end side of the outer peripheral pressure contact surface of the outer tube is more than the concave portion non-forming region. The recess formation region,
When the inner circumferential pressure contact surface of the shaft hole of the housing has the recessed portion forming region and the recessed portion non-formed region, the tip end in the axial direction of the inner peripheral pressure contacting surface of the shaft hole is more axial than the recessed portion non-formed region. The side is all the recess formation region,
A glow plug manufacturing method comprising an outer cylinder press-fitting step of press-fitting the outer cylinder holding the heater in the cylinder hole into the shaft hole of the housing while holding the lubricant in the recess. A method for manufacturing a glow plug according to claim 8 ,
A glow plug manufacturing method comprising an application step of applying the lubricant to at least the recess forming region of the outer peripheral surface of the outer cylinder and the inner peripheral surface of the shaft hole of the housing.

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