JP4177342B2 - Glow plug with combustion pressure detection mechanism and method for manufacturing glow plug with combustion pressure detection function - Google Patents

Description

  The present invention relates to a glow plug with a combustion pressure detecting function that can be used as a start assist device for an internal combustion engine such as a diesel engine and can detect a change in the combustion pressure of the internal combustion engine, and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, a glow plug with a combustion pressure detection function in which a combustion pressure detection function is added to a glow plug for assisting in starting an internal combustion engine is known. For example, an embodiment of the invention of Patent Document 1 discloses such a glow plug with a combustion pressure detection function. This glow plug with a combustion pressure detecting function is configured to be inserted into the cylindrical housing and the inside thereof, and to produce a relative displacement in the axial direction with respect to the housing in accordance with a change in the combustion pressure of the internal combustion engine during use. And a sensor portion (a portion made up of a piezoelectric element, an extraction circuit, etc.) configured to be able to detect a change in combustion pressure based on this relative displacement.

  The glow plug with a combustion pressure detection function is fixed to the housing, a pressing member (inwardly projecting member) disposed on the proximal end side in the axial direction of the sensor portion and pressing the sensor portion toward the distal end side in the axial direction, A surrounding member that surrounds the sensor portion and the pressing member around the axis. Further, the glow plug with a combustion pressure detection function has a lead portion where the lead wire is exposed and a covering portion where the lead wire is covered with a covering member, and is located at a predetermined position radially outside the sensor portion and the pressing member. With the arranged cable. In this cable, the lead portion is electrically connected to the terminal portion (a part of the electrode plate) of the sensor portion and disposed inside the enclosing member, and the covering portion is taken out from the inside of the enclosing member to the outside. It is.

JP 2004-278932 A

  Such a glow plug with a combustion pressure detection function is manufactured as follows. That is, after the glow plug intermediate body is formed by assembling the housing, the center shaft, the sensor portion, the pressing member, etc., the cable lead portion is connected to the terminal portion of the sensor portion by welding or the like. Thereafter, the surrounding member into which the cable is inserted is attached to the housing from the axial base end side, and the surrounding member is fixed to the housing by welding or the like. Next, the cable is moved to a predetermined position radially outside the sensor portion and the pressing member, and the cable is fixed to the surrounding member using a fixing tool or the like. Thereafter, a glow plug with a combustion pressure detection function is completed through a process such as filling the enclosing member with resin.

By the way, when mounting the enclosing member on the housing, the cable is moved to the proximal side in the axial direction so that the encircling member contacts the cable and the cable is not damaged, and is retracted radially inward as much as possible. In this state, the surrounding member is attached to the housing.
However, in the conventional glow plug with a combustion pressure detection function, the cable could not be retracted sufficiently inward in the radial direction due to its structure, so that the surrounding member may come into contact with the cable when the surrounding member is attached to the housing. was there. Moreover, in order to prevent such a contact, since it was necessary to enlarge the dimension (diameter direction dimension) of an enclosing member, the base end side of the glow plug with a combustion pressure detection function tended to enlarge.

  The present invention has been made in view of the present situation, and has a glow plug with a combustion pressure detecting function capable of reducing the dimension in the radial direction of the surrounding member, and a combustion pressure detecting function capable of preventing breakage of a cable during manufacturing. An object is to provide a method for manufacturing a glow plug.

  The solving means includes a cylindrical housing, a heater member that protrudes from the axial front end side of the housing, and generates heat when energized, and is inserted into the housing to reduce the combustion pressure of the internal combustion engine during use. A change in the combustion pressure can be detected on the basis of the relative displacement between the housing and the center shaft, the center shaft being configured to cause a relative displacement in the axial direction with respect to the housing. A sensor part having a terminal part arranged on the radially outer side of the sensor part, a pressing member that is arranged on the axial base end side of the sensor part and presses the sensor part toward the distal end side in the axial direction, and fixed to the housing An encircling member for encircling the sensor unit and the pressing member around an axis, and a cable disposed at a predetermined position radially outside the sensor unit and the pressing member. A glow plug with a combustion pressure detection function, comprising a cable electrically connected to the terminal portion of the sensor portion and taken out from the inside of the surrounding member, wherein the pressing member is at least For the cable connected to the terminal part of the sensor unit, the cable having the concave part opened on the radially outer side and the axial base side is temporarily moved to the base side. After the cable is moved radially inward while inserting a part or a part of the cable into the concave portion of the pressing member, the surrounding member into which the cable is inserted is moved from the proximal end side in the axial direction. A glow plug with a combustion pressure detecting function, which is mounted on a housing and moves the cable to the predetermined position radially outside the sensor part and the pressing member.

  As described above, in the conventional glow plug with a combustion pressure detecting function, when the surrounding member is attached to the housing during the manufacturing process, the surrounding member may come into contact with the cable and the cable may be damaged. Moreover, in order to prevent such a malfunction, it was necessary to enlarge the dimension of the surrounding member in the radial direction.

  On the other hand, in the glow plug with a combustion pressure detecting function of the present invention, the pressing member that presses the sensor portion has a recess that opens at least on the radially outer side and the axially proximal end side. Then, when the enclosure member is attached to the housing, the cable is temporarily moved to the base end side, and further, the cable is inserted while inserting a part of the terminal part of the sensor part or a part of the cable into the concave part of the pressing member. It is moved radially inward. By moving the cable in this way, the cable can be retracted radially inward from the conventional one. For this reason, when mounting the surrounding member on the housing, the surrounding member can be prevented from coming into contact with the cable and being damaged. In addition, since such contact can be avoided, the dimension of the surrounding member in the radial direction can be designed to be small.

  Furthermore, in the above glow plug with a combustion pressure detection function, the concave portion of the pressing member is a bottomed concave portion that opens at least radially outward and axially proximal end but does not open toward the axially distal end side. The glow plug with a combustion pressure detecting function may be formed by pressing the entire base end surface of the sensor portion with the front end surface of the pressing member.

The sensor unit is configured to output a signal based on the pressing force in the axial direction. For this reason, if a partial bias occurs in the pressing force applied to the front end surface and the base end surface of the sensor unit, the sensor may not be able to fully exhibit its original performance.
On the other hand, according to this invention, the recessed part formed in the press member is a bottomed recessed part which does not open to the axial direction front end side. For this reason, the entire base end surface of the sensor unit is uniformly pressed by the distal end surface of the pressing member. Therefore, an uneven load is prevented from being applied to the sensor part during its manufacture and use, and the sensor performance can be improved.

  Another solution is a cylindrical housing, a heater member that protrudes from the axial front end side of the housing, generates heat when energized, and is inserted into the housing. A change in the combustion pressure can be detected on the basis of the relative displacement between the middle shaft that is configured to cause an axial displacement relative to the housing in accordance with the change in the combustion pressure, and the housing and the middle shaft. A sensor part having a terminal part arranged on the radially outer side of the sensor part, a pressing member which is arranged on the proximal side in the axial direction of the sensor part and presses the sensor part toward the distal end side in the axial direction, and the housing And an enclosure member that surrounds the sensor unit and the pressing member around an axis, and a case that is disposed at a predetermined position radially outside the sensor unit and the pressing member. A cable that is electrically connected to the terminal part of the sensor part and is taken out from the inside of the surrounding member, and a method of manufacturing a glow plug with a combustion pressure detecting function, The pressing member has a recess opening at least on the radially outer side and the axial base end side, and for the cable connected to the terminal portion of the sensor unit, the cable is once moved to the base end side, and A first cable moving step of moving the cable radially inward while inserting a part of the terminal portion or a part of the cable into the recess of the pressing member; and after the first cable moving step, A surrounding member attaching step for attaching the surrounding member into which the cable is inserted to the housing from the axial base end side, and after the surrounding member attaching step, the cable is connected to the sensor. And a second cable movement process and the combustion pressure detecting function glow plug manufacturing method comprising moving to the predetermined position in the radial direction outside than the pressing member.

  According to this invention, a press member has a recessed part opened to the radial direction outer side and an axial direction base end side at least. Then, in the first cable moving step, for the cable connected to the terminal portion of the sensor portion, the cable is once moved to the base end side, and further, a part of the terminal portion or a part of the cable is moved to the concave portion of the pressing member. The cable is moved radially inward while being inserted. By moving the cable in this way, the cable can be retracted radially inward from the conventional one. Therefore, after that, in the surrounding member mounting step, when the surrounding member into which the cable is inserted is attached to the housing from the axial base end side, it is possible to prevent the surrounding member from contacting the cable and damaging the cable. In addition, since the cable is retracted radially inward, an enclosing member having a smaller radial dimension than the conventional one can be used.

  Furthermore, in the above method for manufacturing a glow plug with a combustion pressure detection function, the concave portion of the pressing member opens at least radially outward and axially proximally but does not open to the axially distal end. Preferably, the method is a method for manufacturing a glow plug with a combustion pressure detecting function, which is a recess, and the entire base end face of the sensor part is pressed by the tip end face of the pressing member.

  According to this invention, the recessed part formed in the press member is a bottomed recessed part which does not open to the axial direction front end side. For this reason, the entire base end surface of the sensor unit is uniformly pressed by the distal end surface of the pressing member. Therefore, an uneven load is prevented from being applied to the sensor part during its manufacture and use, and the sensor performance can be improved.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show a glow plug 100 with a combustion pressure detection function according to the first embodiment. FIG. 4 shows a pressing metal fitting (pressing member) 170 constituting the glow plug 100 with a combustion pressure detecting function. 1 to 4, the lower side in the drawing is the axial front end side (hereinafter also simply referred to as the front end side), and the upper side in the drawing is the axial direction base end side (hereinafter also simply referred to as the base end side). . The glow plug 100 with a combustion pressure detection function has a sensor unit 160 configured to be able to detect a change in combustion pressure of the internal combustion engine, in addition to being able to generate heat by heating the heater member 110 to assist in starting the internal combustion engine. It is.

  As shown in FIG. 1, the glow plug 100 with a combustion pressure detecting function includes a cylindrical housing 120 extending in a direction along the axis AX (axial direction), and a conductive rod-shaped central shaft held in the housing 120. 140 and a rod-shaped heater member 110 disposed on the front end side of the middle shaft 140. Further, the glow plug 100 with a combustion pressure detection function has, on its proximal end side, a sensor unit 160 configured to be able to detect a change in combustion pressure of the internal combustion engine during use, a press fitting 170 that presses the sensor unit 160, and a sensor unit. A cable 180 connected to 160 and taken out to the outside, a cylindrical surrounding member 190 surrounding the sensor unit 160 and the like are included.

  Among these, the heater member 110 located on the front end side is made of silicon nitride ceramic and has a rod-like shape with the front end being substantially hemispherical. The heater member 110 is disposed such that the tip portion 110s protrudes outward from the housing 120 (heater holding member 126) toward the tip side. As shown in FIG. 2, a heater heating part 111 made of a non-metallic heating element is provided inside the heater tip part 110s. On the other hand, on the outer peripheral surface of the proximal end side of the heater member 110, heater connection portions 112 and 113, which are power supply terminals necessary for the heat generation of the heater heat generating portion 111, are provided at predetermined positions, respectively. Then, both proximal ends of the heater heat generating portion 111 and the heater connecting portions 112 and 113 are electrically connected via heater conductive paths 114 and 115 that are embedded in the heater member 110 and extend in the axial direction.

  As shown in FIGS. 1 to 3, the housing 120 includes a cylindrical housing main body 121, a cylindrical heater holding member 126 that is fixed to the distal end side and holds the above-described heater member 110 inside, and a housing main body. It is comprised from the substantially cylindrical sensor cap 131 fixed to the base end side of 121, and hold | maintaining the sensor part 160 grade | etc., Inside. As shown in FIG. 2, the housing main body 121 and the heater holding member 126 are fixed to each other at the front end of the housing main body 121 by laser welding. Further, as shown in FIG. 3, the housing main body 121 and the sensor cap 131 are also fixed to each other by laser welding at the base end portion 121 k of the housing main body 121.

  Among these, the housing main body 121 is formed with a male screw portion 122 for attaching the glow plug 100 with the combustion pressure detecting function to the mounting hole of the internal combustion engine at an intermediate portion in the axial direction (see FIG. 1). Further, a hexagonal tool engaging portion 123 that engages a tool such as a wrench when screwing is formed on the proximal end side of the housing main body 121 (see FIGS. 1 and 3).

  The heater holding member 126 is in pressure contact with a tapered surface formed in the mounting hole in the mounting hole of the internal combustion engine on the base end side thereof, so that the space between the heater holding member 126 and the mounting hole is kept airtight. A seal portion 127 having a tapered taper surface is formed (see FIGS. 1 and 2). As shown in FIG. 2, the proximal end side of the heater member 110 is press-fitted into the heater holding member 126. Thereby, the heater connecting portion 112 of the heater member 110 and the heater holding member 126 are electrically connected. Further, the base end portion 110k of the heater member 110 is press-fitted into a cylindrical connection ring 117 made of metal. Further, the distal end portion 140s of the middle shaft 140 (the middle shaft main body 141) is inserted into the connection ring 117 from the base end side and fixed to each other by welding. For this reason, the heater member 110 and the middle shaft 140 are mechanically rigidly coupled via the connection ring 117. In addition, the heater connecting portion 113 of the heater member 110 and the middle shaft 140 are electrically connected via the connection ring 117. With such a configuration, the heater member 110 can generate heat when a voltage is applied to the heater holding member 126 (housing 120) and the central shaft 140.

  On the other hand, as shown in FIG. 3, a part (left side in the figure) of the sensor cap 131 extends along the axial direction in order to connect the sensor part 160 held inside thereof and the cable 180 arranged outside thereof. It has the trunk | drum 132 which makes the substantially cylindrical shape opened. The sensor cap 131 is positioned on the distal end side of the body portion 132, and has an annular annular portion 133 that is thinner than the body portion 132, and a radially inner side perpendicular to the axial direction from the base end of the body portion 132. And an inward projecting portion 134 projecting from the inside.

  Next, the middle shaft 140 will be described. The middle shaft 140 is made of iron and is disposed inside the housing 120. The middle shaft 140 includes a middle shaft main body 141 that extends in a bar shape in the axial direction, and a middle shaft base end member 145 (see FIGS. 1 and 3) that is fixed to the base end side and has a bar shape. As shown in FIG. 3, the middle shaft base end member 145 is exposed to the outside, and is configured to allow connection terminals (not shown) to be inserted and connected. The middle shaft base end member 145 has a female screw portion 146 on the tip end side. The female screw portion 146 and the male screw portion 142 formed at the base end of the central shaft main body 141 are screwed and further swaged to fix the central shaft base end member 145 to the central shaft main body 141. Yes.

  As shown in FIG. 3, the middle shaft 140 also has a cylindrical middle shaft sleeve 151 that is inserted through the middle shaft main body 141 and fixed to the middle shaft main body 141 on the proximal end side of the middle shaft main body 141. The middle shaft sleeve 151 is joined to the middle shaft main body 141 by arc welding (argon welding) on the base end side. The central shaft sleeve 151 has a cylindrical cylindrical main body 152 whose front end is inserted into the base end portion 121 k of the housing main body 121, and whose base end protrudes more proximally than the sensor cap 131. The intermediate shaft sleeve 151 also has a flange-shaped outward protrusion 153 that protrudes radially outward at an intermediate position in the axial direction. The outward projecting portion 153 is positioned substantially in the middle between the inward projecting portion 134 of the sensor cap 131 and the base end portion 121k of the housing main body 121 when viewed in the axial direction. Further, in the cylindrical main body 152, the outer periphery on the proximal end side and the outer periphery on the distal end side with respect to the outward projecting portion 153 are surrounded by insulating tubes 154 and 155, respectively.

  Further, as shown in FIGS. 1 and 3, in a space formed between the middle shaft main body 141 of the middle shaft 140 and the housing main body 121 of the housing 120, a predetermined position on the proximal end side of the middle shaft main body 141 has O A ring 149 is arranged. This O-ring 149 is made of heat-resistant fluoro rubber.

  Next, the sensor unit 160 will be described with reference to FIG. The sensor unit 160 is configured on the inner side of the sensor cap 131 on the base end side with respect to the base end portion 121 k of the housing main body 121. The sensor unit 160 includes a first piezoelectric element 161, a first electrode unit 162, a first insulating spacer 163, a second insulating spacer 165, a second electrode unit 166, a second piezoelectric element 167, and an electrode connecting unit (terminal unit). 168. In addition, on the inner side of the sensor cap 131, a pressing fitting (pressing member) 170 that presses the sensor unit 160 toward the distal end side is disposed on the base end side of the sensor unit 160 (base end side of the first piezoelectric element 161). Yes.

  Here, first, the press fitting 170 will be described (see FIG. 4). The pressing metal 170 has a ring shape into which the cylindrical main body 152 of the central shaft sleeve 151 is inserted, and has a flat front end surface 170 sm and a base end surface 170 km. Unlike the conventional one, the pressing metal fitting 170 is open to the radially outer side (lower left in the figure), the radial inner side (upper right in the figure) and the proximal end side (upward in the figure), while the distal end side A bottomed concave portion (concave portion) 171 that does not open is provided in (in the drawing, downward). The bottomed recess 171 has a width of about 3 mm and a depth of about 2 mm. Since a lead portion 181 of the cable 180 described later has a diameter of about 1 mm, a part of the lead portion 181 can be inserted into the bottomed recess 171. In the state in which the glow plug 100 with the combustion pressure detection function is configured, the pressing metal fitting 170 has a bottomed concave portion 171 facing the lead portion 181 side (left side in FIG. 3) of the cable 180 and the base end side ( It is disposed on the base end side of the first piezoelectric element 161. The distal end surface 170 sm of the pressing member 170 uniformly presses the substantially entire surface of the proximal end surface 160 km of the sensor unit 160 toward the distal end side.

  Returning to FIG. 3, details of the sensor unit 160 will be described. In the sensor unit 160, the first piezoelectric element 161, the first electrode unit 162, and the first insulating spacer 163 are arranged in this order from the base end side to the tip end side in the order of the inward projecting portion 134 of the sensor cap 131 and the middle shaft sleeve 151. It is sandwiched between the outward projecting portion 153. Each of these members has a ring shape, and a cylindrical main body 152 of the center shaft sleeve 151 is inserted inside thereof. As described above, the first piezoelectric element 161 is in contact with the pressing metal fitting 170 on the base end side thereof to be electrically connected to each other, and the first piezoelectric element 161 is in contact with the first electrode portion 162 on the tip end side of the electric contact between the surfaces. Connected.

  Further, in the sensor unit 160, the second insulating spacer 165, the second electrode unit 166, and the second piezoelectric element 167 are arranged in this order from the base end side to the tip end side in the order of the outward projecting portion 153 of the central shaft sleeve 151 and the housing body. It is held between the base end 121k of 121. Each of these members also has a ring shape, and the cylindrical main body 152 of the center shaft sleeve 151 is inserted inside the members. The second piezoelectric element 167 is in contact with and electrically connected to the second electrode portion 166 on its base end side, and is in contact with the base end portion 121k of the housing body 121 on its front end side. Electrically connected.

  The first and second insulating spacers 163 and 165 are each made of alumina ceramic. The first and second electrode portions 162 and 166 are made of an iron-nickel alloy and are connected via an elongated plate-like electrode connecting portion (terminal portion) 168 extending in the axial direction. Each of the first and second piezoelectric elements 161 and 167 is made of lead zirconate titanate and is polarized in the axial direction. Based on the change of the compressive stress in the axial direction, the both ends are plus or minus. Generate electric charges. Specifically, the first piezoelectric element 161 is disposed so as to generate a negative charge on the base end face and a positive charge on the front end face when the compressive stress in the axial direction increases. Further, the second piezoelectric element 167 is arranged so as to generate a negative charge on the base end face and a positive charge on the front end face when the compressive stress in the axial direction decreases.

  The sensor cap 131 is laser welded to the outer periphery of the base end portion 121k of the housing body 121 over the entire circumference of the annular portion 133. Since the sensor cap 131 is welded and fixed so that a compressive force in the axial direction is applied to the sensor unit 160, the first and second piezoelectric elements 161 and 167 are always subjected to a compressive load in the axial direction. Yes.

  A cable 180 is electrically connected to the electrode connecting portion 168 that connects the first and second electrode portions 162 and 166 of the sensor portion 160. The cable 180 includes a lead portion 181 with the lead wire exposed and a covering portion 183 with the lead wire covered with a covering member, and the tip of the lead portion 181 is a predetermined position of the electrode connecting portion 168 (in FIG. (Upward) is connected by spot welding. The cable 180 is disposed at a predetermined position on the outer side in the radial direction from the sensor unit 160 and the pressing fitting 170. Specifically, the lead portion 181 is disposed on the outer side in the radial direction than the sensor portion 160 and the pressing fitting 170 and inside the enclosing member 190 described later. Further, the covering portion 183 is disposed on the radially outer side than the sensor portion 160 and the pressing fitting 170, and is taken out from the inside of the surrounding member 190 to the outside.

  With this configuration, the charges (output signals) generated in the first and second piezoelectric elements 161 and 167 are converted into the first electrode portion 162, the second electrode portion 166, the electrode connecting portion 168, the lead portion 181, And it is taken out of the plug through the covering portion 183. And it inputs into control apparatuses, such as ECU, via the charge amplifier etc. which are not shown in figure, and the change of combustion pressure is detected.

  As shown in FIG. 3, the surrounding member 190 is fixed to the housing 120 and surrounds the sensor unit 160 and the like around the axis. Specifically, the surrounding member 190 is joined to the housing main body 121 by welding in a state where the proximal end portion 121k of the housing main body 121 is inserted at the distal end side. The enclosing member 190 includes a substantially cylindrical cylindrical portion 191 (right side in FIG. 3) and a bulging portion 193 (left side in FIG. 3) that protrudes radially outward at a part of the outer periphery of the cylindrical portion 191. Become. The cylindrical portion 191 surrounds the sensor portion 160, the press fitting 170, the sensor cap 131, and the like. Further, in the bulging portion 193, a part of the cable 180 disposed on the radially outer side than the sensor portion 160 and the like is accommodated.

  A metal cable fixing member 195 is caulked and fixed to a part of the covering portion 183 of the cable 180 on the lead portion 181 side, and this cable fixing member 195 is welded to the bulging portion 193 of the surrounding member 190. Yes. Accordingly, it is possible to prevent the first and second electrode portions 162 and 166 and the electrode connecting portion 168 from being deformed and the lead portion 181 from being detached due to a force applied to the lead portion 181 due to the tension of the cable 180 and the like. In addition, a sealing resin 197 made of silicon resin is provided in the surrounding member 190 in order to prevent a decrease in electrical performance such as a decrease in insulation resistance due to moisture or oil adhering to the sensor unit 160, the cable 180, or the like. Filled and formed.

Next, a method for manufacturing the glow plug 100 with the combustion pressure detection function will be described.
First, the proximal end side of the heater member 110 formed by a known method is press-fitted and fixed to the heater holding member 126, and the proximal end portion 110k is coupled to the distal end portion 140s of the central shaft main body 141 via the connection ring 117 ( (See FIG. 2). Next, the heater holding member 126 and the housing main body 121 are fixed by laser welding. Thereafter, the O-ring 149 is pushed into the gap between the housing main body 121 and the central shaft main body 141 from the base end side (see FIG. 3).

  Next, the insulating tubes 154 and 155 are respectively placed on the middle shaft sleeve 151 in advance, and the members constituting the sensor unit 160 are assembled on both sides in the axial direction with the outward projecting portion 153 of the middle shaft sleeve 151 interposed therebetween (FIG. 3). reference). Specifically, first, the first insulating spacer 163, the first electrode portion 162, the first piezoelectric element 161, and the pressing fitting 170 are inserted in this order on the proximal end side of the central shaft sleeve 151. Further, the second insulating spacer 165, the second electrode portion 166, and the second piezoelectric element 167 are inserted in this order on the distal end side of the middle shaft sleeve 151.

  Next, the intermediate shaft main body 141 assembled to the housing main body 121 and the like is inserted into the intermediate shaft sleeve 151 in this state from the distal end side thereof, and the second piezoelectric element 167 is brought into contact with the proximal end portion 121k of the housing main body 121 (see FIG. 3). After that, the sensor cap 131 is attached to this from the proximal end side, and is pressed toward the distal end side with a predetermined pressing force. At that time, the entire surface of the base end surface 160 km of the sensor unit 160 is uniformly pressed by the front end surface 170 sm of the press fitting 170, so that an uneven load is prevented from being applied to the sensor unit 160 and the sensor performance can be improved. . In this state, the annular portion 133 of the sensor cap 131 is welded to the outer periphery of the base end portion 121k of the housing main body 121 over the entire periphery using a YAG laser. Thereafter, the base end of the middle shaft sleeve 151 is arc welded to the middle shaft main body 141 over the entire circumference to form a glow plug intermediate.

  Next, in the cable connecting step, as shown in FIG. 5, using the cable 180 in which the lead wire 181 is formed in advance by exposing the lead wire, the tip of the lead portion 181 is connected to the glow plug intermediate body. Spot welding is performed at a predetermined position (upward in FIG. 5) of the electrode connecting portion 168.

  Next, in the first cable moving step, as shown in FIG. 6, the covering portion 183 of the cable 180 is once moved to the base end side with respect to the pressing fitting 170, and a part of the lead portion 181 is further moved to the pressing fitting 170. The cover 183 is moved radially inward while being inserted into the bottomed recess 171.

  Here, since the press fitting that constitutes the conventional glow plug with the combustion pressure detection function has no bottomed recess, the cable lead cannot be inserted into the bottomed recess. Could not be moved sufficiently radially inward. On the other hand, in this Embodiment 1, since a part of lead part 181 of the cable 180 is inserted in the bottomed recessed part 171, the coating | coated part 183 of the cable 180 can be moved to radial inside rather than before. . Specifically, in the first embodiment, the cable 180 is disposed inside the outer periphery of the sensor cap 131 when viewed in the radial direction.

  Next, in the surrounding member attaching step, as shown in FIG. 7, the surrounding member 190 having the cable 180 inserted inside is attached to the housing 120 from the base end side. At this time, as described above, since the cable 180 is disposed radially inward from the outer periphery of the sensor cap 131, the surrounding member 190 can be prevented from coming into contact with the cable 180. Therefore, the cable 180 can be prevented from being damaged when the surrounding member 190 is attached. In addition, since the cable 180 is sufficiently retracted radially inward, the surrounding member 190 having a smaller radial dimension than that of the conventional one can be used, and the glow plug 100 with the combustion pressure detecting function can be downsized. Can do.

  Next, in the surrounding member fixing step, the base end side of the surrounding member 190 is fixed to the housing body 121 by laser welding over the entire circumference.

  Next, in the second cable moving step, as shown in FIG. 8, the cable 180 is moved to a predetermined position radially outside the sensor unit 160 and the pressing fitting 170. Thereafter, the cable fixing member 195 is caulked and fixed to the covering portion 183 of the cable 180, and the cable fixing member 195 is welded and fixed to the bulging portion 193 of the surrounding member 190.

  Next, the enclosing member 190 is filled with silicon resin and further cured to form a sealing resin 197 (see FIG. 3). Finally, the middle shaft base end member 145 is screwed into the middle shaft main body 141, and further fixed by crimping. Thus, the glow plug 100 with a combustion pressure detection function is completed.

(Embodiment 2)
Next, a second embodiment will be described. Note that the description of the same parts as those in the first embodiment is omitted or simplified. 9 to 11 show a glow plug 200 with a combustion pressure detection function according to the second embodiment. 9 to 11, the lower side in the figure is the axial direction distal end side (the distal end side), and the upper side in the figure is the axial direction proximal end side (the proximal end side). As shown in FIG. 9, this glow plug 200 with a combustion pressure detection function also includes a cylindrical housing 220, a rod-shaped center shaft 240, a rod-shaped heater member 210, a sensor portion 260 that detects combustion pressure, and a press fitting (press member). 270, a cable 280, a surrounding member 290, and the like.

  Of these, the heater member 210 is disposed such that the tip portion 210 s projects outward from the housing 220 toward the tip side. As shown in FIG. 10, the heater member 210 includes a bottomed cylindrical sheath member 213 made of stainless steel and having a substantially hemispherical tip. Inside the sheath member 213, a coil-shaped heater heat generating portion 211 is disposed. The heater heat generating portion 211 is a metal wire made of an iron-chromium alloy, a cobalt-nickel alloy, or the like formed by winding around a rod-shaped insulating rod 212. One end of the heater heat generating portion 211 is welded to the sheath member 213 at the distal end side, and the other end is wound around the distal end portion 240 s of the middle shaft 240 and is electrically connected to the middle shaft 240. Further, the inside of the sheath member 213 is densely filled with the insulating filling powder 215. Further, a rubber packing 216 is inserted in the gap between the sheath member 213 and the central shaft 240 on the proximal end side of the sheath member 213 in order to prevent the insulating filling powder 215 from leaking.

  The housing 220 is made of carbon steel, and is integrally formed as shown in FIGS. 9 to 11 in the second embodiment. As in the first embodiment, the housing 220 (housing main body 221) is formed with a male screw portion 222, a tool engaging portion 223, and a seal portion 227. As shown in FIG. 10, the proximal end side of the heater member 210 is press-fitted into the distal end side of the housing 220 (housing main body 221). Thereby, the sheath member 213 of the heater member 210 and the housing 220 are electrically connected. With such a configuration, the heater member 210 can generate heat when a voltage is applied to the housing 220 and the central shaft 240. On the other hand, as shown in FIG. 11, the housing 220 holds the sensor portion 260 inside in the sensor cap portion 231 on the base end side (base end side of the housing main body 221). The sensor cap portion 231 has a substantially cylindrical shape in which a part (the left side in the figure) is opened along the axial direction in order to connect the sensor portion 260 and the cable 280, and the base end thereof is radially inward. It has an inward protruding portion 234 that protrudes.

  The middle shaft 240 is made of iron and has a middle shaft main body 241 extending in a bar shape in the axial direction, and a middle shaft base end member (not shown in the second embodiment) which is located on the base end side and has a bar shape. As shown in FIG. 11, a male screw portion 242 for screwing a middle shaft base end member having a female screw portion is formed on the base end side of the middle shaft main body 241. The middle shaft 240 has a cylindrical middle shaft sleeve 251 that is inserted through the middle shaft main body 241 on the inner side of the middle shaft main body 241 and welded to the middle shaft main body 241. The middle shaft sleeve 251 has a cylindrical cylindrical main body 252 that has a distal end side inserted into the sensor cap portion 231 of the housing 220, while a part of the proximal end side protrudes to the proximal end side from the sensor cap portion 231. . The outer periphery of the cylindrical main body 252 is surrounded by an insulating tube 254. Further, the middle shaft sleeve 251 also has a flange-like outward projecting portion 253 projecting radially outward from its base end.

  Next, the sensor unit 260 will be described with reference to FIG. The sensor portion 260 is configured inside the sensor cap portion 231 on the proximal end side of the proximal end portion 221k of the housing body 221. The sensor unit 260 includes a piezoelectric element 261, an electrode unit 262, a first insulating spacer 263, a second insulating spacer 265, and a terminal unit 268. Further, on the inner side of the sensor cap portion 231, a pressing fitting (pressing member) 270 that presses the sensor portion 260 toward the distal end side is disposed on the proximal end side of the sensor portion 260.

  The pressing metal fitting 270 basically has the same shape as the pressing metal fitting 170 of the first embodiment (see FIG. 4). That is, the pressing metal fitting 270 has a ring shape into which the cylindrical main body 252 of the central shaft sleeve 251 is inserted, and has a flat front end surface 270 sm and a base end surface 270 km. The pressing metal fitting 270 is formed with a bottomed recess 271 that opens to the radially outer side, the radially inner side, and the proximal end side but does not open to the distal end side (downward in the drawing). The pressing metal fitting 270 also forms the glow plug 200 with the combustion pressure detection function, and the base end of the sensor portion 260 is directed toward the lead portion 281 side (left side in FIG. 11) of the cable 280 to be described later with the bottomed concave portion 271 facing. Arranged on the side. Then, the distal end surface 270 sm of the pressing member 270 uniformly presses substantially the entire base end surface 260 km of the sensor portion 260 toward the distal end side.

  Of the sensor portion 260, the piezoelectric element 260, the electrode portion 262, and the first insulating spacer 263 are protruded in the order from the proximal end side to the distal end side in this order from the inward protruding portion 234 of the sensor cap portion 231 and the outward protrusion of the central shaft sleeve 251. It is sandwiched between the portion 253. Each of these members has a ring shape, and a cylindrical main body 252 of the center shaft sleeve 251 is inserted inside the members. As described above, the piezoelectric element 261 is in electrical contact with the pressing metal fitting 270 on the base end side thereof and is electrically connected to the electrode portion 262 on the distal end side thereof. ing. In the sensor portion 260, the second insulating spacer 265 is sandwiched between the outward projecting portion 253 of the central shaft sleeve 251 and the housing main body portion 221. The second insulating spacer 265 has a ring shape, and the central shaft main body 241 is inserted inside the second insulating spacer 265.

  The electrode portion 262 has a terminal portion 268 that protrudes radially outward from the periphery of the electrode portion 262 at one location. The piezoelectric element 261 is made of lead zirconate titanate, as in the first embodiment, and generates a negative charge on the base end face and a positive charge on the front end face when the axial compressive stress increases. Are arranged as follows. The inward protruding portion 234 of the sensor cap portion 231 faces the inner side in the radial direction and is bent toward the distal end side. For this reason, a compressive load is always applied to the piezoelectric element 261 in the axial direction.

  A cable 280 similar to that of the first embodiment is electrically connected to the terminal part 268 of the electrode part 262 constituting the sensor part 260. The cable 280 includes a lead portion 281 where the lead wire is exposed and a covering portion 283 where the lead wire is covered with a covering member, and the lead portion 281 is connected to a predetermined position of the terminal portion 268 by spot welding. The cable 280 is disposed at a predetermined position on the outer side in the radial direction from the sensor unit 260 and the pressing metal fitting 270. Specifically, the lead portion 281 is arranged on the outer side in the radial direction than the sensor portion 260 and the pressing metal fitting 270 and inside the surrounding member 290 described later. Further, the covering portion 283 is disposed on the radially outer side than the sensor portion 260 and the pressing metal fitting 270 and is taken out from the inside of the surrounding member 290 to the outside.

  As shown in FIG. 11, the surrounding member 290 is fixed to the housing 220 and surrounds the sensor portion 260 and the like around the axis. Specifically, the surrounding member 290 is joined to it by welding in a state where the proximal end portion 221k of the housing main body 221 is inserted at the distal end side thereof. Similar to the surrounding member 190 of the first embodiment, the surrounding member 290 has a substantially cylindrical cylindrical portion 291 (on the right side in FIG. 11) and a bulge that protrudes radially outward at a part of the outer periphery of the cylindrical portion 291. It consists of a protruding portion 293 (left side in FIG. 11). The cylindrical portion 291 surrounds the sensor portion 260, the pressing metal fitting 270, the sensor cap portion 231 and the like. In addition, in the bulging portion 293, a part of the cable 280 disposed on the radially outer side than the sensor portion 260 and the like is accommodated.

  A cable fixing member 295 is caulked and fixed to a part of the covering portion 283 of the cable 280 on the lead portion 281 side, and this cable fixing member 295 is welded to the bulging portion 293 of the surrounding member 290. The enclosing member 290 is filled with a sealing resin 297.

Next, a method for manufacturing the glow plug 200 with the combustion pressure detection function will be described.
First, the heater member 210 and the housing 220 are connected and the heater member 210 and the central shaft 240 are connected by a known method. Next, the second insulating spacer 265 inserted through the central shaft 240 from the base end side is placed on the base end portion 221k of the housing body 221 (see FIG. 11). Thereafter, the middle shaft sleeve 251 covered with the insulating tube 254 in advance is placed on the base end of the second insulating spacer 265. Further, the first insulating spacer 263, the electrode portion 262, the piezoelectric element 261, and the pressing fitting 270 are arranged in this order on the base end of the outward projecting portion 253 of the central shaft sleeve 251. Next, the base end portion of the sensor cap portion 231 (which is in a state extending to the base end side until this step) is bent inward in the radial direction, and the press fitting 270 is brought into contact with the base end surface 270 km to bring the press fitting 270 into the distal end. The inward projecting portion 234 is formed while being pressed to the side. At that time, the entire surface of the base end surface 260 km of the sensor portion 260 is uniformly pressed by the tip end surface 270 sm of the pressing metal fitting 270, so that an uneven load is prevented from being applied to the sensor portion 260 and the sensor performance can be improved. . Thereafter, the base end of the middle shaft sleeve 251 is arc welded to the middle shaft main body 241 over the entire circumference to form a glow plug intermediate.

  Next, in the cable connecting step, as shown in FIG. 12, using the cable 280 in which the lead portion 281 is formed in advance, the tip portion of the lead portion 281 is attached to the sensor portion 260 of the glow plug intermediate body. Among them, spot welding is performed at a predetermined position of the terminal portion 268.

  Next, in the first cable moving step, as shown in FIG. 13, the covering portion 283 of the cable 280 is once moved to the proximal end side with respect to the press fitting 270, and a part of the lead portion 281 is further moved to the press fitting 270. The cover 283 is moved radially inward while being inserted into the bottomed recess 271. As described above, also in the second embodiment, since a part of the lead portion 281 of the cable 280 is inserted into the bottomed concave portion 271, the covering portion 283 of the cable 280 can be moved radially inward than the conventional one. Specifically, the cable 280 is disposed inside the outer periphery of the sensor cap portion 231 when viewed in the radial direction.

  Next, in the surrounding member attaching step, as shown in FIG. 14, the surrounding member 290 through which the cable 280 is inserted is attached to the housing 220 from the base end side. At this time, as described above, since the cable 280 is disposed radially inward from the outer periphery of the sensor cap portion 231, the surrounding member 290 can be prevented from coming into contact with the cable 280. Therefore, the cable 280 can be prevented from being damaged when the surrounding member 290 is attached. In addition, since the cable 280 is sufficiently retracted radially inward, the surrounding member 290 having a smaller radial dimension than the conventional one can be used, and the glow plug 200 with the combustion pressure detecting function can be downsized. Can do.

  Next, in the surrounding member fixing step, the surrounding member 290 is fixed to the housing body 221 by laser welding over the entire circumference.

  Next, in the second cable moving step, as shown in FIG. 15, the cable 280 is moved to a predetermined position radially outside the sensor portion 260 and the pressing fitting 270. Thereafter, the cable fixing member 295 is caulked and fixed to the covering portion 283 of the cable 280, and the cable fixing member 295 is further welded to the bulging portion 293 of the surrounding member 290.

  Next, the enclosing member 290 is filled with resin and further cured to form a sealing resin 297. Finally, a middle shaft base end member (not shown) is screwed into the middle shaft main body 241 and further fixed by crimping. Thus, the glow plug 200 with the combustion pressure detection function is completed. In addition, the same part as the said Embodiment 1 has an effect similar to the said Embodiment 1. FIG.

(Embodiment 3)
Next, a third embodiment will be described. Note that description of the same parts as those in the first or second embodiment is omitted or simplified. FIG. 16 shows a glow plug 300 with a combustion pressure detection function according to the third embodiment. In FIG. 16, the lower side in the figure is the axial front end side (front end side), and the upper side in the figure is the axial base end side (base end side). The glow plug 300 with a combustion pressure detection function also includes a cylindrical housing 320 (housing main body 321), a rod-shaped center shaft 340, a rod-shaped heater member (not shown), a sensor portion 360, a press fitting 370, a cable 380, and a surrounding member 390. Etc. However, in the third embodiment, the structure on the proximal end side of the housing 320 is different from that in the second embodiment. Others are basically the same as the glow plug 200 with the combustion pressure detection function of the second embodiment.

  Specifically, the housing 320 of the third embodiment does not have a portion corresponding to the inward protruding portion 234 of the housing 220 of the second embodiment. Instead, the press fitting 370 is fixed to the base end of the housing 320 (sensor cap portion 331) by welding. Since this welding is performed in a state where the pressing member 370 is pressed toward the distal end side, the pressing fitting 370 maintains the state where the sensor portion 360 is pressed toward the distal end side as in the second embodiment.

  Such a glow plug 300 with a combustion pressure detection function is manufactured in substantially the same manner as the glow plug 200 with a combustion pressure detection function of the second embodiment. The cable connection process and subsequent steps are the same as those in the second embodiment described with reference to FIGS. That is, in the cable connection process, the tip portion of the lead portion 381 is spot welded to the terminal portion 368 of the sensor portion 360 using the cable 380 in which the lead portion 381 is formed in advance.

  Next, in the first cable moving step, the covering portion 383 of the cable 380 is once moved to the proximal end side with respect to the pressing fitting 370 and further a part of the lead portion 381 is inserted into the bottomed recessed portion 371 of the pressing fitting 370. Then, the covering portion 383 is moved inward in the radial direction. Thus, by inserting a part of the lead part 381 into the bottomed recessed part 371, the covering part 383 can be moved radially inward than the conventional one. Also in the third embodiment, the cable 380 is arranged inside the outer periphery of the sensor cap portion 331 when viewed in the radial direction.

  Next, in the surrounding member mounting step, the surrounding member 390 through which the cable 380 is inserted is mounted on the housing 320 from the base end side. At this time, since the cable 380 is retracted radially inward from the outer periphery of the sensor cap portion 331, the surrounding member 390 can be prevented from contacting the cable 380.

  Next, in the surrounding member fixing step, the surrounding member 390 is fixed to the housing body 321 by laser welding over the entire circumference.

  Next, in the second cable moving step, the cable 380 is moved to a predetermined position radially outside of the sensor unit 360 and the pressing fitting 370. Thereafter, the cable fixing member 395 is caulked and fixed to the covering portion 383 of the cable 380, and the cable fixing member 395 is welded to the bulging portion 393 of the surrounding member 390.

  Next, the enclosing member 390 is filled with resin and further cured to form a sealing resin 397. Finally, a middle shaft base end member (not shown) is screwed in and further fixed by caulking. Thus, the glow plug 300 with the combustion pressure detection function is completed.

  In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described first to third embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say.

2 is a half cross-sectional view of a glow plug with a combustion pressure detection function according to Embodiment 1. FIG. It is an expanded sectional view which shows the front end side among the glow plugs with a combustion pressure detection function which concern on Embodiment 1. FIG. It is an expanded sectional view which shows the base end side among the glow plugs with a combustion pressure detection function which concern on Embodiment 1. FIG. It is a perspective view of the press metal fitting which constitutes the glow plug with a combustion pressure detection function concerning Embodiment 1 etc. It is explanatory drawing which shows a mode that a cable is connected to a glow plug intermediate body regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that a cable is once retracted regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the surrounding member is attached to a housing and fixed regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that a cable is moved to a predetermined position and fixed regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 1. FIG. FIG. 6 is a half cross-sectional view of a glow plug with a combustion pressure detection function according to a second embodiment. It is an expanded sectional view which shows the front end side among the glow plugs with a combustion pressure detection function which concern on Embodiment 2. FIG. It is an expansion half sectional view which shows the base end side among the glow plugs with the combustion pressure detection function which concern on Embodiment 2. FIG. FIG. 10 is an explanatory diagram showing a state in which a cable is connected to a glow plug intermediate body in a method for manufacturing a glow plug with a combustion pressure detection function according to a second embodiment. It is explanatory drawing which shows a mode that a cable is once retracted regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 2. FIG. It is explanatory drawing which shows a mode that the surrounding member is attached to a housing and fixed regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 2. FIG. It is explanatory drawing which shows a mode that a cable is moved to a predetermined position and fixed regarding the manufacturing method of the glow plug with a combustion pressure detection function which concerns on Embodiment 2. FIG. It is an expansion half sectional view which shows the base end side among the glow plugs with the combustion pressure detection function which concern on Embodiment 3. FIG.

Explanation of symbols

100, 200, 300 Glow plug with combustion pressure detection function 120, 220, 320 Housing 140, 240, 340 Center shaft 160, 260, 360 Sensor part 160km, 260km (Sensor part) base end face 161 First piezoelectric element 162 First electrode Part 163 First insulating spacer 165 Second insulating spacer 166 Second electrode part 167 Second piezoelectric element 168 Electrode connecting part (terminal part)
170, 270, 370 Press fitting (press member)
170 sm, 270 sm Tip end surface 170 km, 270 km (Press fitting) base end surface 171, 271, 371 Bottomed recess (recess)
180, 280, 380 Cable 181, 281, 381 Lead part 183, 283, 383 Covering part 190, 290, 390 Enclosing member 261 Piezoelectric element 262 Electrode part 263 First insulating spacer 265 Second insulating spacer 268, 368 Terminal part AX Axis

Claims (4)

A tubular housing;
A heater member that protrudes from the front end side in the axial direction of the housing and generates heat when energized;
A middle shaft that is inserted into the housing and configured to cause relative displacement in the axial direction with respect to the housing in accordance with a change in combustion pressure of the internal combustion engine during use;
A sensor unit configured to be able to detect a change in the combustion pressure based on the relative displacement between the housing and the middle shaft, and having a terminal unit disposed on the radially outer side of the sensor unit;
A pressing member disposed on the proximal end side in the axial direction of the sensor unit and pressing the sensor unit toward the distal end side in the axial direction;
An enclosing member fixed to the housing and enclosing the sensor portion and the pressing member around an axis;
A cable that is disposed at a predetermined position radially outside the sensor unit and the pressing member, and that is electrically connected to the terminal unit of the sensor unit and is taken out from the inside of the surrounding member to the outside When,
A glow plug with a combustion pressure detection function comprising:
The pressing member has a recess opening at least on the radially outer side and the axial base end side,
For the cable connected to the terminal part of the sensor part, the cable is temporarily moved to the proximal end side, and further, a part of the terminal part or a part of the cable is inserted into the concave part of the pressing member. While moving the cable radially inward,
The surrounding member through which the cable is inserted is attached to the housing from the axial base end side,
A glow plug with a combustion pressure detection function, wherein the cable is moved to the predetermined position radially outside the sensor portion and the pressing member. A glow plug with a combustion pressure detection function according to claim 1,
The concave portion of the pressing member is a bottomed concave portion that opens at least on the radially outer side and the axial base end side but does not open on the distal end side in the axial direction.
A glow plug with a combustion pressure detection function, wherein the entire base end surface of the sensor unit is pressed by the distal end surface of the pressing member. A tubular housing;
A heater member that protrudes from the front end side in the axial direction of the housing and generates heat when energized;
A middle shaft that is inserted into the housing and configured to cause relative displacement in the axial direction with respect to the housing in accordance with a change in combustion pressure of the internal combustion engine during use;
A sensor unit configured to be able to detect a change in the combustion pressure based on the relative displacement between the housing and the middle shaft, and having a terminal unit disposed on the radially outer side of the sensor unit;
A pressing member disposed on the proximal end side in the axial direction of the sensor unit and pressing the sensor unit toward the distal end side in the axial direction;
An enclosing member fixed to the housing and enclosing the sensor portion and the pressing member around an axis;
A cable that is disposed at a predetermined position radially outside the sensor unit and the pressing member, and that is electrically connected to the terminal unit of the sensor unit and is taken out from the inside of the surrounding member to the outside When,
A method for manufacturing a glow plug with a combustion pressure detection function comprising:
The pressing member has a recess opening at least on the radially outer side and the axial base end side,
For the cable connected to the terminal part of the sensor part, the cable is temporarily moved to the proximal end side, and further, a part of the terminal part or a part of the cable is inserted into the concave part of the pressing member. A first cable moving step of moving the cable radially inward,
After the first cable moving step, the surrounding member through which the cable is inserted, the surrounding member mounting step of mounting the housing from the axial base end side,
A second cable moving step of moving the cable to the predetermined position radially outside the sensor portion and the pressing member after the surrounding member mounting step;
A method for manufacturing a glow plug with a combustion pressure detecting function. A method for manufacturing a glow plug with a combustion pressure detecting function according to claim 3,
The concave portion of the pressing member is a bottomed concave portion that opens at least on the radially outer side and the axial base end side but does not open on the distal end side in the axial direction.
A method for manufacturing a glow plug with a combustion pressure detecting function, wherein the entire base end surface of the sensor portion is pressed by the tip end surface of the pressing member.

Images