JP2013204941A - Method for manufacturing glow plug, and glow plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a glow plug and the glow plug capable of directing an arrangement position of a temperature sensor to a specific direction in a peripheral direction in a combustion chamber of an internal combustion engine.SOLUTION: Before a glow plug 1 is assembled in an internal combustion engine, a main metal fitting 6 and a heater holding member 21 are assembled to a cylinder head fixture simulating the internal combustion engine, and a mark 90 is marked on an outer peripheral surface of a tool engagement part 9 of the main metal fitting 6 assembled in the cylinder head fixture. An arrangement position of a thermocouple 3 is determined based on the mark 90, and the glow plug 1 is assembled. Thereby, the thermocouple 3 can be directed to a specific direction in a combustion chamber of the internal combustion engine.

Description

  The present invention relates to a method for manufacturing a glow plug and a glow plug that are assembled in a mounting hole of an internal combustion engine and have a function of measuring the temperature of a combustion chamber.

  2. Description of the Related Art Conventionally, a glow plug is known in which a temperature sensor is provided at the tip of a heat generating heater and can measure the temperature of a combustion chamber of an internal combustion engine (see, for example, Patent Document 1). On the outer peripheral surface of the glow plug main metal fitting, a screw thread corresponding to the female thread formed in the mounting hole of the internal combustion engine is formed, and the glow plug can be assembled to the mounting hole of the internal combustion engine. When the temperature of the combustion chamber of the internal combustion engine is measured using this glow plug, the glow plug must be assembled in the mounting hole of the internal combustion engine so that the temperature sensor is arranged toward a desired position in the combustion chamber. .

JP 2001-336468 A

  However, conventionally, since the glow plug is manufactured without considering the circumferential position (orientation) of the temperature sensor, when the glow plug is assembled to the mounting hole of the internal combustion engine, the temperature sensor is placed at a desired position in the combustion chamber. It was difficult to arrange in (direction).

  The present invention has been made to solve the above-described problems, and in a glow plug assembled to an internal combustion engine, a temperature sensor can be disposed in a specific circumferential direction in a combustion chamber of the internal combustion engine. To provide a method for manufacturing a glow plug and a glow plug.

  The method for manufacturing a glow plug according to the first aspect of the present invention includes a step in which a threaded portion that engages with an internal thread provided in a mounting hole of an internal combustion engine is formed on an outer peripheral surface of the internal thread and provided in the mounting hole of the internal combustion engine. A cylindrical housing that extends in the axial direction, a heater that is held by the housing in a state in which its front end protrudes from the front end of the housing, and the heater A glow plug manufacturing method for manufacturing a glow plug including a temperature sensor provided at a position radially displaced from the axial center of the heater, wherein at least the locking portion of the housing is provided in a cylinder head jig. A mounting step of mounting on the cylinder head jig in a state of engaging with the stepped portion, and the housing mounted on the cylinder head jig in the mounting step. A marking step for marking a mark indicating a specific direction in the circumferential direction, a removal step for removing the housing that has been marked in the marking step from the cylinder head jig, and a position of the mark marked in the marking step. A position determining step for determining an arrangement position of the temperature sensor in the circumferential direction based on the assembly, and an assembly step for assembling a glow plug so that the temperature sensor is arranged at the arrangement position determined in the position determining step.

  In this case, in the method for manufacturing a glow plug having the above-described configuration, the circumferential direction of the housing (the circumferential direction of the glow plug after the glow plug is assembled) after the mounting step of mounting the housing on a cylinder head jig simulating an internal combustion engine is specified. A marking process for marking a mark indicating a direction is performed. Thus, when assembled in the internal combustion engine, the circumferential position of the temperature sensor provided at the tip of the heater protruding into the combustion chamber can be grasped. That is, the circumferential position of the temperature sensor can be grasped based on the mark outside the internal combustion engine. Therefore, the circumferential position of the temperature sensor in the combustion chamber of the internal combustion engine can be directed to a desired position (orientation).

  Further, in the glow plug manufacturing method, the position of the mark marked in the marking step may be a portion on the rear end side with respect to the screw portion formed in the housing. In this case, since the position of the marked mark is outside the internal combustion engine, in the work of assembling the glow plug to the internal combustion engine, the work can be performed while checking the circumferential direction of the temperature sensor using the mark. Even after the glow plug is assembled to the internal combustion engine, the portion on the rear end side of the glow plug screw head is located outside the internal combustion engine, so check the circumferential direction in which the temperature sensor is arranged. be able to.

  Further, in the glow plug manufacturing method, the arrangement position of the temperature sensor determined in the position determination step may be the same circumferential position as the position of the mark marked in the marking step. In this case, the arrangement position of the temperature sensor can be easily determined.

  The glow plug according to the second aspect of the present invention may be a glow plug manufactured by any one of the above-described methods for manufacturing a glow plug. In this case, when the glow plug is attached to the internal combustion engine, the circumferential position of the temperature sensor can be directed to a desired position (orientation) in the combustion chamber of the internal combustion engine.

1 is an external view of a glow plug 1. FIG. FIG. 2 is a cross-sectional view taken along the line I-I in FIG. 1. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. It is a figure which shows a mounting process. It is a figure which shows a marking process. It is a figure which shows a removal process. It is a figure which shows a position determination process. It is a figure which shows an assembly process.

  Hereinafter, a first embodiment of a glow plug embodying the present invention will be described with reference to FIG. 1 to FIG. In the following, in the direction of the axis O of the glow plug 1, the side on which the thermocouple 3 is arranged (lower side in the figure) is the front end side of the glow plug 1, and the opposite side (upper side in the figure) is the rear end. It will be described as a side.

  First, the structure of the glow plug 1 according to the present embodiment will be described. A glow plug 1 shown in FIG. 1 is assembled, for example, in a mounting hole 110 of an internal combustion engine 100 of a direct injection diesel engine, and is used as a heat source that assists ignition at the start of the internal combustion engine 100.

  As shown in FIG. 1, the glow plug 1 includes a ceramic heater 2, a thermocouple 3, a heater holding member 21, a metal shell 6, a screw portion 7, a tool engaging portion 9, a terminal 11, and the like.

  The ceramic heater 2 will be described. As shown in FIG. 1, the ceramic heater 2 protrudes from the distal end of a cylindrical heater holding member 21 attached to the distal end of the metal shell 6 toward the distal end side. As shown in FIGS. 2 and 3, the ceramic heater 2 is formed in a round bar shape. The tip 22 has a base 23 made of an insulating ceramic that is hemispherically curved.

  A heating element 27 having a substantially U-shaped cross section made of conductive ceramic is embedded in the base 23. Both ends of the heat generating element 27 are folded back in a substantially U shape in accordance with the curved surface of the distal end portion 22. Connected to both ends of the heating element 27 are lead portions 28 extending substantially parallel to each other along the axis O toward the rear end side of the ceramic heater 2. The ceramic heater 2 corresponds to a “heater” in the present invention.

  As shown in FIGS. 2 and 3, a groove 35 is formed on the outer surface of the base 23 along the direction of the axis O. Inside the groove 35, a thermocouple 3 in which the tips of two metal wires 38 (only one is shown in FIG. 3) is welded is embedded in a cement 37. The thermocouple 3 corresponds to the “temperature sensor” of the present invention.

  The heater holding member 21 will be described. As shown in FIGS. 1 and 3, the heater holding member 21 is a cylindrical fitting extending in the direction of the axis O. The ceramic heater 2 is held in the cylindrical hole of the heater holding member 21. And the front-end | tip part 22 of the ceramic heater 2 protrudes from the cylinder hole. A thick flange 25 is formed on the rear end side of the body 26 of the heater holding member 21. The body portion 26 and the flange portion 25 are connected by a tapered locking portion 24. Therefore, when the glow plug 1 is assembled into the mounting hole 110 of the internal combustion engine 100, the locking portion 24 is locked to the stepped portion 130 provided in the mounting hole 110. Thereby, the airtight leak of the combustion chamber 105 through the attachment hole 110 can be prevented.

  The metal shell 6 will be described. As shown in FIG. 1, the metal shell 6 is a cylindrical metal member having a shaft hole 61 penetrating in the direction of the axis O. Inside the shaft hole 61, a ceramic shaft 2 (refer to FIGS. 4 to 7) and the like that are electrically connected to the ceramic heater 2 and the rear end portion of the ceramic heater 2 and extend in the direction of the axis O are inserted. . A fitting fitting portion (not shown) of the heater holding member 21 is disposed in a portion of the shaft hole 61 corresponding to the distal end portion 62 of the metal shell 6. Further, the joining portion between the heater holding member 21 and the tip end portion 62 of the metal shell 6 is laser-welded from the outer periphery of the heater holding member 21. Thereby, the metal shell 6 and the heater holding member 21 are joined together. In addition, what arrange | positioned the heater holding member 21 in the front-end | tip part 62 of the metal shell 6 corresponds to the "housing" in this invention.

  The screw part 7 will be described. As shown in FIG. 1, a screw portion 7 in which a screw thread portion 71 is formed is provided on the outer peripheral surface on the rear end side of the metal shell 6. The screw thread portion 71 is a male screw provided on the outer peripheral portion of the screw portion 7 and is screwed with a female screw 120 provided in the mounting hole 110 of the internal combustion engine 100. A tool engagement portion 9 is provided on the rear end side of the screw portion 7. The tool engaging portion 9 is a columnar member having a hexagonal shape in plan view. For example, when the glow plug 1 is assembled into the mounting hole 110 of the internal combustion engine 100, a tool (not shown) is engaged with the tool engaging portion 9, and the glow plug 1 is assembled into the mounting hole 110 of the internal combustion engine 100.

  A cylindrical resin insulator 91 and a cable connection terminal 11 are arranged in this order at the rear end portion of the tool engaging portion 9 in this order (see FIGS. 4 to 7). The insulator 91 is fixed between the tool engaging portion 9 and the terminal 11 by the terminal 11 being crimped and fixed to the middle shaft 15 by the crimping portion 10. The terminal 11 is fitted with a connector (not shown), and power is supplied to the glow plug 1 from an external circuit.

  A method for manufacturing a glow plug will be described with reference to FIGS. This method for manufacturing a glow plug includes an attachment process, a marking process, a removal process, a position determination process, and an assembly process. A cylinder head jig 100A shown in FIG. 4 is a jig imitating the internal combustion engine 100 to which the glow plug 1 is actually assembled. As with the internal combustion engine 100, the cylinder head jig 100A includes a combustion chamber 105A, a mounting hole 110A, a female screw 120A, and a stepped portion 130A. Further, the cylinder head jig 100 </ b> A can be attached to and detached from the glow plug 1 in the same manner as the internal combustion engine 100.

[Installation process]
The mounting process will be described with reference to FIG. As in the case of assembling the glow plug 1 to the internal combustion engine 100, the metal shell 6 and the heater holding member 21 holding the ceramic heater 2 before being assembled to the cylinder head jig 100A are assembled. Specifically, the threaded portion 71 of the threaded portion 7 of the metal shell 6 is screwed with the female screw 120A of the cylinder head jig 100A, and a tool (not shown) is engaged with the tool engaging portion 9, so that the glow plug While rotating 1, the metal shell 6 and the heater holding member 21 are assembled to the cylinder head jig 100 </ b> A. At this time, the metal shell 6 is screwed into the cylinder head jig 100A until the engaging portion 24 of the heater holding member 21 and the stepped portion 130A of the cylinder head jig 100A are engaged.

[Marking process]
The marking process will be described with reference to FIG. When the mounting process shown in FIG. 4 is completed and the metal shell 6 (specifically, the metal shell 6 and the heater holding member 21) is screwed into the cylinder head jig 100A and fixed, the tip of the ceramic heater 2 is placed. The part 22 protrudes into the combustion chamber 105A. In this state, a mark 90 is marked on the outer peripheral surface of the tool engaging portion 9. For example, in FIG. 5, a mark 90 is marked on the front side of the tool engaging portion 9 with a heat-resistant paint. The mark 90 only needs to know the relative position between the circumferential position of the mark 90 of the tool engaging portion 9 and the circumferential position of the tip 22 of the ceramic heater 2. As shown in FIG. 5, it is not always necessary to mark the mark 90 on the front side of the tool engaging portion 9 (the front side in FIG. 5).

[Removal process]
The removal process will be described with reference to FIG. The metal shell 6 and the heater holding member 21 mounted on the cylinder head jig 100A are removed from the cylinder head jig 100A. Specifically, the metal shell 6 and the heater holding member 21 are moved to the cylinder head while a tool (not shown) is engaged with the tool engaging portion 9 and the glow plug 1 is rotated in the direction opposite to that in the mounting process. Remove from jig 100A.

[Position determination process]
The position determination process will be described with reference to FIG. The circumferential position of the thermocouple 3 in the ceramic heater 2 is determined based on the position of the mark 90 marked on the tool engaging portion 9 of the metal shell 6 removed from the cylinder head jig 100A. For example, the arrangement position of the thermocouple 3 is determined so as to have the same circumferential direction as the mark 90.

[Assembly process]
The assembly process will be described with reference to FIG. The glow plug 1 is assembled so that the thermocouple 3 is in the arrangement position determined in the position determination step shown in FIG. For example, as shown in FIG. 8, the glow plug 1 is assembled so that the thermocouple 3 is positioned in the same circumferential direction as the mark 90. Thereby, when attached to the internal combustion engine 100, the glow plug 1 capable of directing the thermocouple 3 to a desired position (direction) in the combustion chamber 105 is completed.

  As described above, in the present embodiment, before assembling the glow plug 1 to the internal combustion engine 100, the metal shell 6 and the heater holding member 21 are assembled to the cylinder head jig 100A imitating the internal combustion engine 100, and the cylinder head treatment is performed. A mark 90 is marked on the outer peripheral surface of the tool engaging portion 9 of the metal shell 6 assembled to the tool 100A. The glow plug 1 that can direct the thermocouple 3 to a desired position (orientation) in the combustion chamber 105 of the internal combustion engine 100 by assembling the glow plug 1 by determining the arrangement position of the thermocouple 3 based on the mark 90. It can be easily manufactured.

  In addition, the structure shown by the said embodiment is an illustration, and various changes are possible. In the first embodiment, the mark 90 is marked on the tool engaging portion 9, but the portion where the mark 90 is marked is not limited to the tool engaging portion 9. When the glow plug 1 is assembled to the internal combustion engine 100, any portion may be used as long as it is located outside the internal combustion engine 100.

  In the first embodiment, the latching portion 24 is formed on the heater holding member 21 and the heater holding member is joined to the tip of the metal shell 6. You may apply the structure which formed with the material and provided the latching | locking part in the front-end | tip part of a metal shell. In this case, the metal shell provided with a locking portion at the tip corresponds to the “housing” of the present invention. In the mounting process of the first embodiment, the heater holding member 21 that is scheduled to be joined to the metal shell 6 in the assembly process is assembled to the cylinder head jig 100A together with the metal shell 6. Instead of 21, a dummy member having the same shape as the heater holding member 21 may be used.

DESCRIPTION OF SYMBOLS 1 Glow plug 2 Ceramic heater 3 Thermocouple 6 Main metal fitting 7 Screw part 21 Heater holding part 22 Tip part 24 Locking part 61 Shaft hole 90 Mark 100 Internal combustion engine 110 Mounting hole 120 Female thread 130 Step part 100A Cylinder head jig 130A Step part

Claims (4)

A screw portion that engages with a female screw provided in the mounting hole of the internal combustion engine is formed on the outer peripheral surface of the internal combustion engine, and a locking portion that can be engaged with a step portion provided in the mounting hole of the internal combustion engine is formed. A cylindrical housing extending in the direction, a heater held by the housing with its own tip protruding from the tip of the housing, and a position of the heater that is radially displaced from the axial center of the heater A glow plug manufacturing method for manufacturing a glow plug with a temperature sensor, comprising:
A mounting step of mounting on the cylinder head jig in a state where at least the locking portion of the housing is engaged with a step portion provided on the cylinder head jig;
A marking step for marking a mark indicating a specific direction in the circumferential direction with respect to the housing mounted on the cylinder head jig in the mounting step;
A removal step of removing the housing from which the marking has been completed in the marking step from the cylinder head jig,
A position determining step for determining an arrangement position in the circumferential direction of the temperature sensor based on the position of the mark marked in the marking step;
An assembly step of assembling a glow plug so that the temperature sensor is arranged at the arrangement position determined in the position determination step.   The method for manufacturing a glow plug according to claim 1, wherein a position of the mark marked in the marking step is a portion on a rear end side with respect to the screw portion formed in the housing.   The glow plug according to claim 1 or 2, wherein the arrangement position of the temperature sensor determined in the position determination step is the same circumferential position as the position of the mark marked in the marking step. Manufacturing method.   A glow plug manufactured by the method for manufacturing a glow plug according to claim 1.

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