JP6139137B2 - Glow plug and glow plug structure - Google Patents

Description

  The present invention relates to a glow plug used for assisting in starting a diesel engine, and a glow plug structure having a connector cap attached thereto.

  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. Further, a conductive member such as a rod-shaped central shaft that is electrically connected to the heater terminal and extends toward the rear end side in the axial direction is inserted into the housing. Furthermore, on the rear end side of the housing, a terminal member connected to the rear end portion of the conductive member and electrically connected to the heater via the conductive member is disposed so as to protrude from the rear end portion of the housing. . In addition, an insulating member such as an insulating spacer or an O-ring is interposed between the terminal member and the conductive member and the housing, and the rear end portion of the housing is sealed while electrically insulating them. . The terminal member is mounted with a connector cap including an external connector terminal to which a cable used for electrical connection with the outside is connected, and a cap member that includes the external connector terminal and extends from the cable.

  For example, Patent Document 1 discloses such a glow plug. As shown in FIG. 5 of Patent Document 1, by attaching (caping) a connector cap (cap 80) to a terminal member (pin terminal 93), electricity from the outside (battery) by a cable (lead wire 84) is provided. Connection is made.

JP 2006-250459 A

As described above, the conventional connector cap is held only by the terminal member of the glow plug using the external connector terminal. For this reason, when the connector cap vibrates due to the vibration of a vehicle or the like equipped with this glow plug over a long period of time, stress is applied to the terminal member and the insulating member interposed between the conductive member and the housing, and the terminal member , The sealing performance between the conductive member or the housing and the insulating member is lowered, and there is a possibility that foreign matter and moisture enter the inside of the glow plug.
In particular, in recent years, glow plugs are often mounted deep in the engine head, and there are many foreign substances such as oil around them, passing through gaps between terminal members, conducting members or housings and insulating members. As a result, foreign matter enters the inside of the glow plug, and problems such as short circuits are likely to occur.

  The present invention has been made in view of such a situation, and a glow which has a reduced sealing property between a terminal member, a conducting member or a housing and an insulating member, and prevents foreign matter and moisture from entering the inside. It is an object of the present invention to provide a plug and a glow plug structure in which a connector cap is attached thereto.

  One aspect thereof is a heater that generates heat when energized, a housing that holds the heater directly or indirectly on the front end in the axial direction along its own axis, and an electrical connection to the heater that is inserted into the housing. A conductive member extending toward the rear end side in the axial direction, and a terminal member connected to the rear end portion of the conductive member and disposed so as to protrude from the rear end portion of the housing toward the rear end side in the axial direction. And the insulator, and is interposed between at least one of the terminal member and the conducting member and the housing, and seals the rear end portion of the housing while electrically insulating between them. An insulating member, wherein the housing has an outer connector terminal that is detachably joined to the outer peripheral portion of the rear end portion of the housing in the axial direction with respect to the terminal member. An engagement portion formed on an inner peripheral portion of the cap member, including a cap member that includes the external connector terminal and covers the terminal member and the rear end portion of the housing. A glow plug having an engaged portion that is detachably engaged in the axial direction and engages the connector cap in the axial direction.

This glow plug has an engaged portion for engaging the engaging portion of the cap member in the axial direction so as to be detachable in the axial direction and locking the connector cap in the axial direction on the outer peripheral portion of the rear end portion of the housing. Yes.
Therefore, in a state where the connector cap is mounted on the glow plug, the connector cap is locked to the rear end portion of the housing. That is, the connector cap is not only held by the terminal member, but is also held by the rear end portion of the highly rigid housing fixed to the engine head. Thereby, even when the vibration of the vehicle or the like is repeatedly transmitted to the connector cap, the vibration of the connector cap is suppressed, and the stress applied to the insulating member through the terminal member due to the vibration of the connector cap is reduced. Or a clearance gap is produced between a housing and an insulation member, and it is prevented that a sealing performance falls. Also, since not only the terminal member but also the insulating member and the rear end of the housing are covered with the connector cap, foreign matters such as oil can be prevented from entering the glow plug through the rear end of the housing. You can also.
In addition, as a form of the engaging part and the engaged part, specifically, the engaging part of the cap member has a convex shape and the engaged part of the housing has a concave shape to engage each other. On the contrary, the cap member engaging portion may be concave and the housing engaged portion may be convex to engage each other.

In addition, when the heater and the terminal member are connected to each other via a rod-shaped middle shaft in the housing, that is, in a glow plug that uses the middle shaft as a conductive member, the connector cap passes through the terminal member to the middle shaft during vibration. Since the transmitted stress is also reduced, it is possible to prevent the central shaft from breaking due to fatigue failure due to vibration.
In recent years, since the diameter of the housing (main metal shell) and the central shaft has been reduced, the above-described problems are likely to occur. For this reason, in particular, when the housing and the central shaft have a small diameter, for example, when the screw diameter of the male screw portion of the housing is M8 or less, the effect is great.

  Further, in the above-described glow plug, the engaged portion is recessed in the outer peripheral portion of the rear end portion of the housing, and protrudes inwardly in the inner peripheral portion of the cap member. It is preferable that the projecting portion is a groove portion to be engaged.

  This glow plug has a groove as an engaged portion. By making the engaged portion a groove portion, a glow plug can be provided in which the engaged portion is simply provided by cutting or the like.

  Furthermore, in the glow plug described above, the housing has a tool engaging portion in which the outer peripheral portion forms a hexagonal column shape at the rear end portion, and the groove portion is a hexagonal column-shaped tool engaging portion. The glow plugs may be formed by forming the six corners extending in the axial direction at the same position in the axial direction.

  This glow plug has a tool engaging portion at the rear end portion of the housing, and the groove portions are formed at the same position in the axial direction at the six corners of the tool engaging portion. Since the corner portion of the tool engaging portion is thick, even if the groove portion is provided, the strength is hardly lowered, and the glow plug is highly reliable.

  Further, in the above-described glow plug, it is preferable that the tool engagement portion be a glow plug in which the rear end side in the axial direction from the groove portion is tapered toward the rear end side. .

  In this glow plug, the rear end side in the axial direction with respect to the groove portion of the tool engaging portion is a tapered portion. Accordingly, when the connector cap is mounted and the convex portion (engagement portion) is engaged with the groove portion (engaged portion), the connector cap is easily mounted.

  Further, in the above-described glow plug, the groove portion is a V-groove portion having a V-shaped cross section in the axial direction, and the groove surface on the rear end side in the axial direction of the V-groove portion forms the axis line. The angle θa may be a glow plug formed by making the angle of the taper portion larger than the angle θb formed by the axis (θa> θb).

  In particular, in this glow plug, the groove is a V-groove, and θa> θb. Thereby, when attaching a connector cap, while making it easy to attach, a connector cap can be made hard to remove | deviate.

  Furthermore, in any one of the glow plugs described above, the housing may have a male screw portion for attachment on an outer peripheral surface thereof, and the male screw portion may be a glow plug having a screw diameter of M8 or less.

This glow plug is a small-diameter glow plug having a male screw portion for attachment with a screw diameter of M8 or less, such as M8 or M6, in the housing. The smaller the glow plug diameter, the shorter the distance between the housing and the terminal member (or the conductive member that conducts to it) and the thinner the insulating member, so vibration is transmitted from the connector cap to the terminal member. In such a case, it is difficult to ensure insulation and sealability between the terminal member and the housing via the insulation member. In addition, since the housing has a small diameter, the rigidity of the housing is reduced and the housing is susceptible to vibration. However, in this glow plug, the connector cap is locked at the rear end portion of the housing to reduce the stress applied to the insulating member through the terminal member as the connector cap vibrates. By suppressing the influence of vibration, it is possible to prevent a decrease in insulation and a decrease in sealing performance between the terminal member and conductive member via the insulating member and the housing.
In particular, when the heater and the terminal member are connected by a rod-shaped middle shaft (conducting member), the stress transmitted from the connector cap to the middle shaft through the terminal member is also reduced. For this reason, even if the screw diameter of the male screw portion is set to M8 or less, such as M8 and M6, and the diameter of the center shaft is reduced accordingly, the center shaft can be prevented from breaking due to fatigue failure due to vibration. .

  In another aspect, a heater that generates heat when energized, a housing that holds the heater directly or indirectly on the front end side in the axial direction along its own axis, and a conductor that is inserted into the housing and electrically connected to the heater A conductive member extending toward the rear end side in the axial direction, and a terminal member connected to the rear end portion of the conductive member and disposed so as to protrude from the rear end portion of the housing toward the rear end side in the axial direction. And the insulator, and is interposed between at least one of the terminal member and the conducting member and the housing, and seals the rear end portion of the housing while electrically insulating between them. An external connector terminal that is detachably coupled to the terminal member in the axial direction, and an insulating material, and includes the external connector terminal. A glow plug structure equipped with a connector cap comprising the terminal member of the lug and the cap member covering the rear end of the housing, wherein the cap member of the connector cap engages with an inner peripheral portion thereof The housing includes an engaging portion of the cap member detachably engaged with the outer peripheral portion of the rear end portion in the axial direction, and the connector cap is locked in the axial direction. A glow plug structure having an engaged portion.

In this glow plug structure, a connector cap including an external connector terminal and a cap member that encloses the external connector and covers a terminal member of the glow plug and a rear end portion of the housing is attached to the glow plug. And the cap member of the connector cap has an engaging portion on the inner peripheral portion thereof, and the housing is engaged with the outer peripheral portion of the rear end portion thereof so that the engaging portion of the cap member is detachable in the axial direction. An engaged portion for locking the connector cap in the axial direction is provided.
As a result, the connector cap is locked to the rear end portion of the metal shell, so that the connector cap is held not only at the terminal member but also at the rear end portion of the highly rigid housing fixed to the engine head. Accordingly, the stress applied to the insulating member through the terminal member due to the vibration of the connector cap is reduced, and a gap is generated between the terminal member, the conductive member or the housing and the insulating member, thereby preventing the sealing performance from being lowered. . In addition, since not only the terminal member but also the insulating member and the rear end of the housing are covered with a connector cap, a glow that prevents foreign matters such as oil from entering the glow plug via the rear end of the housing. A plug structure can be obtained.
Further, when the terminal member and the heater are connected via a rod-shaped metal middle shaft (conducting member), the stress transmitted from the connector cap to the middle shaft through the terminal member during vibration is reduced, and the middle shaft is caused by vibration. It is also possible to prevent breakage due to fatigue failure.

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 among the glow plugs which concern on embodiment. It is a fragmentary sectional view about the site | part of the rear end side among the glow plug structures which attached the connector cap to the glow plug which concerns on embodiment. It is the external view which expanded the tool engaging part vicinity among the site | parts of the rear-end side of the glow plug which concerns on embodiment. It is a fragmentary broken sectional view about the part by the side of the back end among glow plug structures concerning a modification.

  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 including the ceramic heater 130 in the glow plug 100. 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 central shaft 120, a ceramic heater 130 (heater), a ring member 140, an outer cylinder 150, a pin terminal 160 forming a terminal member, 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. The thread diameter of the male thread portion 111 is M8, and the metal shell 110 of the glow plug 100 according to the present embodiment is compared with a conventional general glow plug (having a thread diameter of M10, M12, etc.) The diameter is small.
Further, a tool engaging portion 113 is formed on the outer peripheral portion of the metal base end portion 110k, which is the rear end portion of the metal shell 110, to form a hexagonal column and to engage the attachment tool. On the other hand, an in-hole taper portion 115 that expands 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. It is said that.

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 middle shaft 120 is inserted into the metal shell 110 with the middle shaft base end portion 120k protruding 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.
As the metallic shell 110 has a small diameter, the central shaft 120 has also been reduced in diameter.

  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. In this state, the ceramic heater 130 is press-fitted. The electrode extraction part 138 provided in the ceramic heater 130 is in contact with the outer cylinder 150 from the inside, and the outer cylinder 150 and the electrode extraction part 138 are electrically connected.

  Further, the outer cylinder base end portion 150k of the outer cylinder 150 has a small diameter and is fitted in the metal fitting front end portion 110s of the metal shell 110. The outer cylinder 150 and the metal shell 110 are fixed to each other by a welded portion 159 formed between the outer cylinder base end portion 150k and the metal fitting front end portion 110s. 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 coupled to an external connector terminal 82 to which a cable 83 for supplying power from an external power source (not shown) is connected when a connector cap 80 described later is attached. Further, an O-ring 161 made of an insulator and a cylindrical insulating spacer 163 are disposed on the tip side GS of the pin terminal 160. Specifically, the O-ring 161 and the insulating spacer 163 are disposed in a gap from the middle shaft 120 in the metal base end portion 110k of the metal shell 110 (the large diameter hole 110hk of the shaft hole 110h). Thereby, the pin terminal 160 is electrically connected to the electrode extraction portion 137 which is one terminal of the ceramic heater 130 via the central shaft 120 and the ring member 140. Further, the pin terminal 160 and the central shaft 120 and the metal shell 110 are electrically insulated via an O-ring 161 and an insulating spacer 163, and the metal base end of the metal shell 110 is further insulated by the O-ring 161 and the insulating spacer 163. The portion 110k (the large diameter hole 110hk of the shaft hole 110h) is sealed.

  Next, a glow plug structure 200 in which a connector cap 80 is attached to the glow plug 100 according to the present embodiment will be described with reference to FIG. FIG. 3 is a partially broken sectional view of the glow plug structure 200 with respect to the rear end side GK.

The connector cap 80 is connected to the pin terminal 160 of the glow plug 100 so as to be detachably coupled in the axial direction HJ, and a terminal is connected to one end 82a (upper side in FIG. 3) of the external connector terminal 82. A cable 83 that is caulked and connected by a caulking portion 84; and a cap member 81 that is made of an insulating resin and includes the external connector terminal 82 and the cable 83 is drawn out.
The cap member 81 covers the pin terminal 160 of the glow plug 100 and the tool engaging portion 113 of the metal base end portion 110k, which is the rear end portion of the metal shell 110, and is fitted on these.
The cap member 81 holds the external connector terminal 82 and surrounds and holds the holder 81a made of resin and the holder 81a, and surrounds the pin terminal 160 and the tool engaging portion 113 of the metal shell 110. The cap body 81b has a substantially U-shaped cross section. Specifically, after the cable 83 and one end 82a of the external connector terminal 82 are crimped and connected by the terminal caulking portion 84, the external connector terminal 82 is fixed in the holder 81a, and then resin-molded from the outside of the holder 81a. The cap body 81b is molded to produce the cap member 81.

  In addition, a convex portion 85 that protrudes inward is formed on a distal end inner peripheral portion 86 of the axial direction HJ distal end side GS in the inner peripheral surface 81m of the cap member 81 (cap body 81b). On the other hand, the hexagonal columnar tool engagement portion 113 of the metal base end 110k of the metal shell 110 has six corners extending in the axial direction HJ at the same position in the axial direction HJ, and the cross section in the axial direction HJ is V-shaped. A V-groove 116 that is a groove having a shape is formed. Thereby, the convex part 85 of the cap member 81 is detachably engaged with the V groove part 116 (groove part) of the tool engaging part 113 of the metal shell 110 in the axial direction HJ, and the metal base end part 110k ( A tool engaging portion 113) locks the connector cap 80 in the axial direction HJ.

Furthermore, as shown in FIG. 4A, in the tool engaging portion 113 of the metal shell 110, the rear end side GK in the axial direction HJ from the V groove 116 is a conical surface whose diameter decreases toward the rear end GK. The tapered portion 117 is formed as follows.
Then, as shown in FIG. 4B in which the portion A in FIG. 4A is enlarged, an angle θa formed by the groove surface on the rear end side GK in the axial direction HJ of the V groove portion 116 with the axis AX, and a tapered portion The angle θb that 117 forms with the axis AX is in a relationship of θa> θb. Accordingly, when the connector cap 80 is moved toward the front end GS in the axial direction HJ and attached to the glow plug 100, it is easy to attach, while the connector cap 80 is moved to the rear end GK in the axial direction HJ. Thus, when detaching, the connector cap 80 is difficult to come off.

  In the glow plug 100 and the glow plug structure 200 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. The pin terminal 160 corresponds to the “terminal member” in the present invention, and the middle shaft 120 corresponds to the “conducting member” in the present invention. The O-ring 161 and the insulating spacer 163 correspond to the “insulating member” in the present invention, and the metal base end portion 110k of the metal shell 110 corresponds to the “rear end portion” in the present invention. Further, the tool engaging portion 113 of the metal base end portion 110k of the metal shell 110 corresponds to the “outer peripheral portion” in the present invention, and the tip inner peripheral portion 86 of the cap member 81 of the connector cap 80 is the “inner peripheral portion” in the present invention. Is equivalent to.

  As described above, in the glow plug 100 of the present embodiment, the cap member 81 protrudes from the tool engaging portion 113 (outer peripheral portion) of the metal base end portion 110k (rear end portion) of the metal shell 110 (housing). A portion 85 (engagement portion) is detachably engaged in the axial direction HJ, and has a V-groove 116 (engaged portion) for locking the connector cap 80 in the axial direction HJ.

Therefore, in a state where the connector cap 80 is attached to the glow plug 100, the connector cap 80 is locked to the metal base end portion 110k (tool engaging portion 113) of the metal shell 110. That is, the connector cap 80 is not only held by the pin terminal 160 (terminal member), but is also made of an iron-based material, and the metal base end 110k of the highly rigid metal shell 110 fixed to the engine head (not shown). (Tool engaging portion 113) is also held. As a result, even when vibration of a vehicle (not shown) or the like is repeatedly transmitted to the connector cap 80, the vibration of the connector cap 80 is suppressed. The stress repeatedly applied to the (insulating member) is reduced. For this reason, a gap is generated between the pin terminal 160 (terminal member), the middle shaft 120 (conducting member) or the metal shell 110 (housing) and the O-ring 161 and the insulating spacer 163 (insulating member), and the sealing performance is lowered. Is prevented. Further, since not only the pin terminal 160 but also the insulating spacer 163 and the metal base end part 110k which is the rear end part of the metal shell 110 are covered with the connector cap 80, the glowing via the rear end side GK of the main end metal fitting 110 is performed. It is also possible to prevent foreign matter such as oil from entering the plug 100.
Furthermore, in the glow plug 100 according to the present embodiment, stress transmitted from the connector cap 80 to the center shaft 120 through the pin terminal 160 during vibration is reduced, so that the center shaft 120 can be prevented from breaking due to fatigue failure due to vibration.

  Further, in the glow plug 100 of this embodiment, as the engaged portion, the tool engaging portion 113 (outer peripheral portion) of the metal base end portion 110k (rear end portion) of the metal shell 110 is recessed in a concave shape, and the cap member 81 is The front end inner peripheral portion 86 (inner peripheral portion) has a V groove portion 116 (groove portion) that protrudes inward and engages with a convex portion 85 that forms an engaging portion. Thus, by making the engaged portion the V groove portion 116 (groove portion), the glow plug 100 in which the engaged portion is easily provided by cutting or the like can be obtained.

  In the glow plug 100 of the present embodiment, the tool engaging portion 113 is provided at the metal base end portion 110k (rear end portion) of the metal shell 110, and the groove portion 116 has six corner portions of the tool engaging portion 113. Are formed at the same position in the axial direction HJ. Since the corner portion of the tool engaging portion is thick, even if the groove portion 116 is provided, the strength is hardly lowered and the glow plug 100 is highly reliable.

  Further, in the glow plug 100 according to the present embodiment, the taper portion 117 is formed in the tool engagement portion 113 such that the rear end side GK in the axial direction HJ from the V groove portion 116 (groove portion). Thereby, when the connector cap 80 is mounted and the convex portion 85 (engagement portion) is engaged with the V-groove portion 116 (groove portion, engaged portion), the connector cap 80 can be easily mounted.

  Further, in the glow plug 100 of the present embodiment, the groove portion is the V groove portion 116, and the angle θa between the groove surface of the V groove portion 116 on the rear end side GK in the axial direction HJ and the axis line AX, and the taper portion 117 is the axis line AX. The relation of the angle θb is θa> θb. As a result, when the connector cap 80 is attached, the connector cap 80 can be easily attached while the connector cap 80 is difficult to come off.

Further, in the glow plug 100 of the present embodiment, the metal shell 110 has a male screw portion 111 for attachment with a screw diameter of M8, and the metal shell 110 has a small diameter. As a result, the distance between the metal shell 110 and the middle shaft 120 is shortened, and the O-ring 161 and the insulating spacer 163 are thin, so that the pin terminal 160 and the middle shaft 120 via the O-ring 161 and the insulating spacer 163 It is difficult to ensure insulation and sealability with the metal shell 110. Further, since the metal shell 110 has a small diameter, the rigidity of the metal shell 110 is lowered and is easily affected by vibration.
However, in this glow plug 100, the connector cap 80 is locked at the metal base end portion 110 k (rear end portion) of the metal shell 110, and the O-ring 161 and the insulating spacer are passed through the pin terminals 160 according to the vibration of the connector cap 80. Since the stress applied to 163 (insulating member) is reduced, the influence of vibration is suppressed, and the pin terminal 160 (terminal member) and the middle shaft 120 (conducting member) through the O-ring 161 and the insulating spacer 163 (insulating member). It is possible to prevent a decrease in insulation and a decrease in sealing performance between the metal shell 110 and the metal shell 110 (housing).
Further, since the stress transmitted from the connector cap 80 to the center shaft 120 through the pin terminal 160 is also reduced, the thread diameter of the male screw portion 111 is set to M8 or less, and accordingly, the center shaft 120 is reduced in diameter. Even in such a case, the middle shaft 120 can be prevented from breaking due to fatigue failure due to vibration.

Further, in the glow plug structure 200 of the present embodiment, the glow plug 100 includes the external connector terminal 82 and the external connector 82, and the pin terminal 160 (terminal member) and the metal shell 110 (housing) of the glow plug 100. A connector cap 80 including a cap member 81 covering the metal base end portion 110k (rear end portion) is attached. The cap member 81 of the connector cap 80 has a convex portion 85 (engagement portion) at the tip inner peripheral portion 86 (inner peripheral portion), and the metal shell 110 has its metal base end portion 110k (rear end portion). ) Is engaged with the convex portion 85 (engagement portion) of the cap member 81 in the axial direction HJ so that the connector cap 80 is locked in the axial direction HJ. It has the groove part 116 (engaged part).
As a result, the connector cap 80 is locked to the metal base end portion 110k (rear end portion) of the metal shell 110, so that the connector cap 80 is fixed not only to the pin terminal 160 (terminal member) but also to the engine head. It is also held by the metal base end portion 110k (rear end portion) of the highly rigid metal shell 110 (housing). Therefore, the stress applied to the O-ring 161 and the insulating spacer 163 (insulating member) through the pin terminal 160 due to the vibration of the connector cap 80 is reduced, and the pin terminal 160 (terminal member), the middle shaft 120 (conducting member) or the metal shell 110 is reduced. A gap is generated between the (housing) and the O-ring 161 and the insulating spacer 163 (insulating member), thereby preventing the sealing performance from being deteriorated. Further, since not only the pin terminal 160 but also the insulating spacer 163 and the metal base end portion 110k of the metal shell 110 are covered with the connector cap 80, the oil component is introduced into the glow plug 100 via the rear end side GK of the metal shell 110. Thus, the glow plug structure 200 can be obtained in which foreign substances such as the like are prevented from entering.
Furthermore, in the glow plug structure 200 of the present embodiment, the stress transmitted from the connector cap 80 to the middle shaft 120 through the pin terminal 160 during vibration can be reduced, and the middle shaft 120 can be prevented from breaking due to fatigue failure due to vibration. .

In this embodiment, the tool engaging portion 113 of the metal shell 110 is provided with a concave V-groove 116 as an engaged portion, and is engaged with the inner peripheral portion 86 (inner peripheral portion) of the tip end of the cap member 81. The convex part 85 was provided as a part.
However, conversely, the engaged portion can be convex and the engaging portion can be concave. However, in this embodiment, since the engaged portion is provided in the tool engaging portion 113, it is preferable that the engaged portion is concave so as not to affect the engagement of the attachment tool.

(Deformation)
Next, a modification of the above-described embodiment will be described with reference to FIG. In the above-described embodiment, the tool engaging portion 113 having a hexagonal column shape is formed on the outer peripheral portion of the metal base end portion 110k of the metal shell 110. The cap member 81 of the connector cap 80 covered the tool engaging portion 113 of the metal shell 110.
On the other hand, in the present modified embodiment, the metal shell 110 has a shape extending from the tool engagement portion 113 to the rear end side GK. And the V groove part which makes a round in the circumferential direction in the outer peripheral part of the metal fitting base end part 110k (rear end part) on the rear end side GK from the tool engaging part 113 in the metal shell 110, and has a V-shaped cross section. 116 is formed. On the other hand, a convex portion 85 that protrudes inward is formed on the distal end inner peripheral portion 86 (inner peripheral portion) on the axial direction HJ distal end side GS of the inner peripheral surface 81 m of the cap member 81. And the convex part 85 (engagement part) of the cap member 81 is engaged with the V groove part 116 (engaged part) of the metal fitting base end part 110k of the metal shell 110 so as to be detachable in the axial direction HJ. The connector cap 80 is locked to the metal fitting base end portion 110k (rear end portion) of 110.

  In this modification, in a state where the connector cap 80 is attached to the glow plug 100, the connector cap 80 is not only held by the pin terminal 160, but also the tool engagement of the highly rigid metal shell 110 fixed to the engine head. The metal base end portion 110k on the rear end side GK with respect to the portion 113 is also held. Thereby, even when the vibration of the vehicle or the like is repeatedly transmitted to the connector cap 80, the vibration of the connector cap 80 is suppressed, and the O-ring 161 and the insulating spacer 163 (insulating member) through the pin terminal 160 with the vibration of the connector cap 80. The stress applied repeatedly is reduced. Therefore, as in the embodiment, there is a gap between the pin terminal 160 (terminal member), the middle shaft 120 (conducting member) or the metal shell 110 (housing) and the O-ring 161 and the insulating spacer 163 (insulating member). Further, it is possible to prevent the sealing performance from being lowered and to prevent foreign matters such as oil from entering.

In this modification, a concave V-groove 116 is provided as an engaged portion on the outer peripheral portion of the metal base end portion 110k (rear end portion) of the metal shell 110, and the tip inner peripheral portion 86 ( A convex convex portion 85 is provided as an engaging portion on the inner peripheral portion.
However, on the contrary, the engaged portion provided on the outer peripheral portion of the metal base end portion 110k may be convex, and the engaging portion provided on the inner peripheral portion 86 of the cap member 81 may be concave.

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 and the modification, a so-called ceramic glow plug including the ceramic heater 130 is illustrated as the glow plug 100. However, the glow plug is not limited to this, and as a heater, a so-called metal glow plug having a sheath heater in which a heat generating coil or a heat generating coil and a control coil are accommodated and filled with insulating powder in a metal sheath. Also good.
Further, in the embodiment and the modification, the ceramic heater 130 is indirectly held via the outer cylinder 150 at the metal fitting tip portion 110s on the tip side GS of the metal shell 110, but the heater is directly attached to the tip side GS of the metal shell 110. The thing of the form to hold | maintain may be sufficient.
Further, in the embodiment, the glow plug 100 in which the thread diameter of the male thread portion 111 of the metal shell 110 is M8 is exemplified, but the present invention is applied to a glow plug having a smaller diameter such as a thread diameter of M6, for example. You can also.

AX Axis HJ Axial direction GS Front end GK Rear end 100 Glow plug 110 Metal shell (housing)
110k bracket base end (rear end)
110 m (outside metal) outer peripheral surface 111 male thread 113 tool engaging part (outer peripheral part)
116 V-groove (groove, engaged portion)
117 Tapered part 120 Middle shaft (conduction member)
130 Ceramic heater (heater)
140 Ring member 150 Outer cylinder 160 Pin terminal (terminal member)
161 O-ring (insulating member)
163 Insulating spacer (insulating member)
80 connector cap 81 cap member 82 external connector terminal 83 cable 85 convex portion (engagement portion)
86 Tip inner circumference (inner circumference)
200 Glow plug structure

Claims (7)

A heater that generates heat when energized;
A housing in which the heater is held directly or indirectly on the front end side in the axial direction along its own axis;
A conducting member inserted into the housing, electrically conducting to the heater, and extending toward the rear end side in the axial direction;
A terminal member connected to the rear end portion of the conducting member and arranged to protrude toward the rear end side in the axial direction from the rear end portion of the housing;
An insulating member made of an insulator, interposed between at least one of the terminal member and the conducting member and the housing, and electrically insulating between the two while sealing the rear end portion of the housing A glow plug comprising:
The housing is on the outer periphery of the rear end,
An external connector terminal that is detachably coupled to the terminal member in the axial direction, and a cap member that is made of an insulating material, encloses the external connector terminal, and covers the terminal member and the rear end portion of the housing. Among the connector caps provided, an engagement portion formed on an inner peripheral portion of the cap member is detachably engaged in the axial direction so as to engage the connector cap in the axial direction. Glow plug. The glow plug according to claim 1,
The engaged portion is
A glow plug that is a groove portion that is recessed in the outer peripheral portion of the rear end portion of the housing and that protrudes inwardly in the inner peripheral portion of the cap member and engages with a convex portion that forms the engaging portion. The glow plug according to claim 2,
The housing has a tool engaging portion in which the outer peripheral portion forms a hexagonal column shape at the rear end portion,
The groove portion is a glow plug formed in six axial portions extending in the axial direction among the hexagonal columnar tool engaging portions at the same position in the axial direction. The glow plug according to claim 3,
A glow plug in which the rear end side in the axial direction of the tool engaging portion is tapered from the groove portion, and the diameter of the tool engaging portion is reduced toward the rear end side. The glow plug according to claim 4,
The groove portion is a V groove portion having a V-shaped cross section in the axial direction,
Of the V-groove part, an angle θa formed by the groove surface on the rear end side in the axial direction and the axis is as follows:
A glow plug formed by making the taper portion larger than an angle θb formed by the axis (θa> θb). The glow plug according to any one of claims 1 to 5,
The housing has a male screw part for mounting on the outer peripheral surface thereof,
The male thread part is a glow plug whose thread diameter is M8 or less. A heater that generates heat when energized;
A housing in which the heater is held directly or indirectly on the front end side in the axial direction along its own axis;
A conducting member inserted into the housing, electrically conducting to the heater, and extending toward the rear end side in the axial direction;
A terminal member connected to the rear end portion of the conducting member and arranged to protrude toward the rear end side in the axial direction from the rear end portion of the housing;
An insulating member made of an insulator, interposed between at least one of the terminal member and the conducting member and the housing, and electrically insulating between the two while sealing the rear end portion of the housing In a glow plug comprising
An external connector terminal detachably coupled to the terminal member in the axial direction, and a cap made of an insulating material, enclosing the external connector terminal, and covering the terminal member of the glow plug and the rear end portion of the housing A glow plug structure equipped with a connector cap comprising:
The cap member of the connector cap has an engagement portion on an inner peripheral portion thereof,
The housing includes an engaged portion that engages the engaging portion of the cap member with the outer peripheral portion of the rear end portion so as to be detachable in the axial direction, and locks the connector cap in the axial direction. A glow plug structure having:

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