JP2009243709A - Glow plug and method of manufacturing glow plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a pressure receiving area of a pressure sensor in a glow plug with the pressure sensor. <P>SOLUTION: The glow plug includes a cylindrical housing 120, a heater 150 disposed on one end of the housing 150, and a sensor 520 for detecting the displacement of the heater 150 to the housing 120. A power supply member 300 electrically connected with the heater 150 and transmitting the displacement of the heater 150 to the sensor 520 in the housing 120 is disposed in the housing 120. Further a lead member 400 for supplying electric power to the heater 150 through the power supply member 300 is disposed. The power supply member 300 has a through-hole 302 penetrating through one end side to the other end side, and the lead member 400 inserted into the through-hole 302 and the power supply member 300 are joined at one end side of the through-hole 302 of the power supply member 300. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for detecting the combustion pressure of an internal combustion engine in a glow plug used in an internal combustion engine of self-ignition type.

  In a self-ignition type internal combustion engine such as a diesel engine, a pressure sensor is provided in a glow plug for assisting start-up to detect the combustion pressure of the internal combustion engine. In such a glow plug, the displacement of the heater to which combustion pressure is applied is transmitted to the sensor using a central shaft for supplying electric power to the heater (for example, see Patent Document 1). More specifically, the pressure in the combustion chamber is applied to the heater, the pressure is transmitted as stress to the central axis, and the combustion pressure is detected by the sensor.

  Patent Document 2 proposes storing the pressure sensor in a glow plug body (housing) in order to simplify the structure of the pressure pickup heating bar including the pressure sensor and the heating element (heater). Yes.

JP 2006-46822 A JP 2007-120939 A

  By the way, the center shaft for supplying electric power to the heater is provided from the heater side (front end side) to the outside (rear end side) of the internal combustion engine. For this reason, when the pressure sensor is stored in the housing, a through hole for passing the central shaft is provided at the center of the pressure sensor. Therefore, the pressure receiving area of the pressure sensor (the cross-sectional area of the surface perpendicular to the pressure receiving direction) is limited by the size of the through hole. On the other hand, it is desirable to increase the pressure receiving area of the pressure sensor in order to increase the load resistance of the sensor.

  On the other hand, when a portion (displacement transmitting portion) that transmits displacement in the central shaft is deformed, the load applied to the pressure sensor is reduced. Therefore, in order to suppress a decrease in the load applied to the pressure sensor, the outer diameter of the displacement transmission unit is increased so that the deformation amount of the displacement transmission unit is reduced. In general, it is difficult to increase the difference in outer diameter of a member formed integrally, such as an intermediate shaft. Therefore, the outer diameter of the central shaft at the position of the pressure sensor cannot be made sufficiently small, and it is difficult to reduce the diameter of the through hole provided in the pressure sensor and to sufficiently increase the pressure receiving area of the pressure sensor. For example, a large-diameter portion (for example, an outer diameter of 4 mm) as a displacement transmission portion is formed on one end side from a columnar metal material that becomes the central shaft, and is inserted into a through-hole provided in the pressure sensor. This is a case where a small-diameter portion (for example, φ1 mm) as a part is formed adjacent to the other end side.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a technique for increasing the pressure receiving area of a pressure sensor in a glow plug with a pressure sensor.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A glow plug,
A tubular housing;
A heater provided at one end of the housing;
A sensor provided in the housing and detecting a displacement along a direction connecting the one end and the other end of the heater with respect to the housing;
A power supply member provided between the heater and the sensor in the housing, electrically connected to the heater, and mechanically transmitting displacement of the heater to the sensor;
A lead member disposed in the housing from the power supply member toward the other end than the sensor, and supplying electric power from an external power source to the heater via the power supply member,
The power supply member has a through hole penetrating from the one end side to the other end side,
The lead member inserted into the through hole and the power supply member are joined on the one end side of the through hole of the power supply member.

  According to this application example, the lead member that supplies electric power to the heater and the power supply member that is also used for transmission of the displacement are separated, so that the outer diameter of the lead member can be further reduced. . Therefore, it becomes easy to increase the pressure receiving area of the sensor. Further, the power feeding member and the lead member inserted through the through hole of the power feeding member are joined at one end side of the through hole of the power feeding member. Therefore, when a force is applied to the lead member, the stress applied to the joint portion is reduced, so that breakage of the joint portion can be suppressed.

[Application Example 2]
A glow plug as described in Application Example 1,
The lead member is movable in a cross-sectional direction of the through hole on the other end side of the through hole.

  According to this application example, the lead member is movable in the cross-sectional direction of the through hole on the other end side. When the lead member moves in the cross-sectional direction, a part of the cross-sectional force applied to the lead member is dispersed in the linear direction of the lead member (direction in which the lead wire extends). Therefore, the shear stress applied to the lead member due to the contact between the lead member and the end portion of the through hole can be further reduced, and the breakage of the lead member can be suppressed.

[Application Example 3]
A glow plug according to application example 1 or 2,
The glow plug, wherein the lead member has an outer diameter on the one end side larger than a diameter of the through hole.

  According to this application example, the outer diameter of one end portion side of the lead member is larger than the diameter of the through hole. Therefore, even when a direction force is applied to the other end of the lead member, the lead member is prevented from coming off from the power supply member.

[Application Example 4]
A glow plug according to any one of application examples 1 to 3,
The joint between the lead member and the power supply member is made by welding. Glow plug.

  According to this application example, the lead member and the power feeding member are joined by welding, so that the joint portion is limited to one end side of the power feeding member. Therefore, the lead member is suppressed from being fixed on the other end side of the through hole, and the stress applied to the lead member can be further reduced.

[Application Example 5]
A method of manufacturing a glow plug,
The one end and the other end of the heater with respect to the housing are electrically connected to a heater provided at one end of the housing and disposed between the heater and the sensor in the housing. A power supply member that mechanically transmits a displacement along a direction connecting the sensor to the sensor, the power supply member having a through hole from the one end side to the other end side; and
Forming the one end portion side of the lead member inserted through the through hole as a large diameter portion whose outer diameter is larger than the diameter of the through hole; and
And a step of joining the large diameter portion and the power feeding member on the one end side of the through hole.

  According to this application example, it is possible to more easily manufacture a glow plug in which the joint portion between the lead member and the power feeding member is not easily broken.

[Application Example 6]
A method of manufacturing a glow plug according to Application Example 5,
The method of manufacturing a glow plug, wherein the joining of the large diameter portion and the power supply member is performed by welding.

  According to this application example, the large diameter portion where the outer diameter of the lead member is larger than the diameter of the through hole and the power supply member are welded. Therefore, the diameter reduction of the lead member by welding is suppressed, and disconnection of the lead member can be suppressed.

  Note that the present invention can be realized in various modes. For example, a glow plug, a glow plug manufacturing method, a glow plug manufactured by the manufacturing method, an internal combustion engine start assist device using the glow plug, an internal combustion engine using the start assist device, and the internal combustion engine It can be realized in the form of the moving body used.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A1. Glow plug structure:
A2. Configuration of power supply mechanism:
A3. Effects of the embodiment:
A4. Assembling method of heater assembly:
B. Second embodiment:

A1. Glow plug structure:
FIG. 1 is an external view showing an external appearance of a glow plug as one embodiment of the present invention. The glow plug 100 includes a wiring holding part 110, a metal shell 120 (also referred to as “housing”), an outer cylinder 130, a tip chip 140, and a heater 150.

  The wiring holding unit 110 holds a sensor cable 112 that outputs an output signal of a pressure sensor (described later) provided in the glow plug 100 to the outside, and an energization cable 114 for supplying electric power to the heater 150. . In the wiring holding part 110, the plurality of core wires of the sensor cable 112 are respectively connected to a plurality of sensor signal lines (not shown) connected to the pressure sensor. Further, the core wire of the energization cable 114 is connected to a lead wire (described later) for supplying power to the heater 150.

  The metal shell 120 is a cylindrical member, and is attached to a cylinder head of a self-ignition internal combustion engine such as a diesel engine. In the first embodiment, the metal shell 120 is made of carbon steel (S45C). However, as the material of the metal shell 120, various materials such as stainless steel (for example, SUS630, SUS430) can be used as long as the material is high strength. At the end of the metal shell 120 on the wiring holding portion 110 side, an engaging portion 122 that engages with a tool used when attaching to the cylinder head is formed. A screw portion 124 for fixing the glow plug 100 to the cylinder head is formed in the middle portion of the metal shell 120. By rotating the engaging portion 122 with a tool, the cylinder head and the screw portion 124 are fastened, and the glow plug 100 is attached to the cylinder head. Thereby, the heater 150 of the glow plug 100 is exposed to the combustion chamber of the internal combustion engine. In the following, the direction along the axis O on the heater 150 side (arrow R direction in FIG. 1) is also referred to as “front end side”, and the direction on the wiring holding portion 110 side (arrow L direction in FIG. 1) is referred to as “rear end”. Also called “side”.

  The outer cylinder 130 is a cylindrical member in which a flange 132, a thin part 134, and a heater holding part 136 are formed. The flange 132 is formed in a bowl shape in order to define the positional relationship between the outer cylinder 130 and the metal shell 120 along the axis O. The thin portion 134 is formed thinner than other portions of the outer cylinder 130 so as to be deformed by the pressure in the combustion chamber. The heater holding part 136 holds the heater 150 press-fitted into the outer cylinder 130. The outer cylinder 130 is formed of SUS630. In addition, as a material of the outer cylinder 130, various materials (for example, marage steel, SUS430, pure titanium, titanium alloy (Ti-6Al-4V)) having repeated proof stress and low Young's modulus can be used. However, it is also possible to form only the thin portion 134 with such a material. In this case, the other part of the outer cylinder 130 can be formed of other types of high-strength materials.

  The tip tip 140 is a cylindrical member formed of SUS430. The tip tip 140 can also be formed of carbon steel or other stainless steel. The tip tip 140 has a cylindrical portion 142 whose outer diameter is substantially constant along the axis O, and a tapered portion 144 whose outer diameter becomes narrower toward the tip side. Thus, by providing the taper portion 144, when the glow plug is tightened to the cylinder head, the tip tip 140 presses and deforms the taper sheet surface provided on the cylinder head side, thereby making the combustion chamber airtight. It can be secured. The metal shell 120 and the tip tip 140 are welded with the flange 132 of the outer cylinder 130 sandwiched therebetween. Thereby, the metal shell 120, the outer cylinder 130, and the tip chip 140 are fixedly joined.

  FIG. 2 is a cross-sectional view showing a configuration around the pressure detection mechanism (hereinafter also referred to as “main part”) of the glow plug 100 of the first embodiment. As shown in FIG. 2, the pressure detection mechanism is incorporated in the metal shell 120.

  Inside the metal shell 120, the heater 150 is press-fitted into the ring 200. The ring 200 is a cylindrical member having an inner diameter that is substantially the same as that of the heater 150. A base member 300 is press-fitted on the rear end side of the ring 200. The ring 200 is formed of SUS630, and the base member 300 is formed of SUS430. Note that the ring 200 and the base member 300 can be formed of other materials (carbon steel, other stainless steel, etc.) as long as they are conductive and have high strength.

  The base member 300 is formed with a tapered portion 312, a fitting portion 314, a body portion 316, and a positioning portion 318 in this order from the front end side to the rear end side. The outer diameter of the fitting portion 314 is substantially the same as the inner diameter of the ring 200 (that is, the outer diameter of the heater 150). By providing the tapered portion 312 having the outer diameter narrowing toward the distal end side at the distal end side of the fitting portion 314, the base member 300 can be easily pressed into the ring 200. The trunk 316 has an outer diameter that is substantially the same as the outer diameter of the ring 200. Therefore, when the base member 300 is press-fitted into the ring 200, the ring 200 hits the body 316, and the positional relationship along the axis O between the base member 300 and the ring 200 is defined. The positioning portion 318 on the rear end side of the body portion 316 is fitted with a positioning member (not shown) and defines the position in the radial direction (direction perpendicular to the axis O) of an insulating plate and a sensor element to be described later. Note that the outer diameter of the body portion 316 is appropriately set depending on the structure of the glow plug 100. The outer diameter of the trunk 316 is set to, for example, 3.5 mm to 5.8 mm.

  A through hole 302 is provided at the center of the base member 300. A chamfered portion 304 whose inner diameter increases toward the distal end side is formed on the distal end side of the through hole 302. A lead wire 400 for energizing the heater 150 is passed through the through hole 302. The lead wire 400 is joined to the base member 300 on the distal end side of the base member 300. The inner diameter of the through hole 302 is appropriately set in consideration of the outer diameter (hereinafter also referred to as “wire diameter”) and the material of the lead wire 400. The relationship between the wire diameter and the inner diameter of the through hole 302 and the method of attaching the lead wire 400 to the base member 300 will be described later. In the example of FIG. 2, the chamfered portion 304 is provided in the through hole 302, and breakage of the lead wire 400 can be suppressed. However, the chamfered portion 304 can be omitted.

  On the rear end side of the base member 300, a first insulating plate 510, a sensor element 520 that functions as a pressure sensor, a second insulating plate 530, and an element stopper member 600 are arranged in this order. The insulating plates 510 and 530 are disk-shaped members formed of alumina, and the sensor element 520 is a disk-shaped member formed of lithium niobate. The insulating plates 510 and 530 and the sensor element 520 are provided with a through hole larger than the wire diameter of the lead wire 400 at the center thereof. The insulating plates 510 and 530 may be formed of a high-strength and insulating material such as zirconia or silicon nitride in addition to alumina. Further, the sensor element 520 may be formed of a piezoelectric material (for example, quartz) other than lithium niobate. It is also possible to form the sensor element 520 with a piezoresistive material. In this case, the structure around the sensor element 520 is appropriately changed as the piezoresistive material is used.

  The element stopper member 600 is a member provided with a through hole larger than the wire diameter of the lead wire 400 at the center thereof, and is formed of SUS430. Note that the element fixing member 600 can be formed of another high-strength material (for example, carbon steel or stainless steel). The element stopper member 600 includes an insertion portion 610 having an outer diameter that is substantially the same as the inner diameter of the outer cylinder 130, and a cylindrical portion 620 having an outer diameter that is substantially the same as the outer diameter of the outer cylinder 130. The element stopper member 600 is welded to the outer cylinder 130 in a state where the insertion portion 610 is inserted into the outer cylinder 130. It is also possible to join the element stopper member 600 and the outer cylinder 130 by other methods such as brazing.

  The element stopper member 600 and the outer tube 130 are welded by assembling the heater 150, the ring 200, the base member 300, the insulating plates 510 and 530, the sensor element 520, and the element stopper member 600. It is performed with a load (referred to as “preload”) applied. Specifically, a heater assembly including the heater 150, the ring 200, and the base member 300 to which the lead wire 400 is attached is assembled. After the assembled heater assembly is press-fitted into the outer cylinder 130, the first insulating plate 510, the sensor element 520, and the second insulating plate 530 are inserted into the outer cylinder 130. Thereafter, the insertion portion 610 is inserted into the outer cylinder 130, and an overlapping portion between the insertion portion 610 and the outer cylinder 130 is laser-welded from the outer peripheral side of the outer cylinder 130 while applying a load in the distal direction to the element stopper member 600. In addition, welding can be performed by various methods such as arc spot welding in addition to laser welding. Moreover, you may join the insertion part 610 and the outer cylinder 130 by other joining methods, such as brazing.

  The glow plug 100 (FIG. 1) formed in this way is attached to the cylinder head of the internal combustion engine, and detects the pressure in the combustion chamber of the internal combustion engine. When the pressure in the combustion chamber varies, the thin portion 134 of the outer cylinder 130 is deformed, and the heater 150 is displaced along the axis O with respect to the metal shell 120. The displacement of the heater 150 is transmitted to the sensor element 520 through the ring 200, the base member 300, and the first insulating plate 510. On the other hand, the sensor element 520 is fixed to the metal shell 120 via the second insulating plate 530, the element stopper member 600, and the outer cylinder 130. Therefore, the displacement of the sensor element 520 relative to the metal shell 120 is restricted, and the load applied to the sensor element 520 changes according to the displacement of the heater 150 relative to the metal shell 120. As a result, a charge corresponding to the displacement of the heater 150 is generated in the sensor element 520 formed of the piezoelectric material. The generated charges are output to the outside through a sensor signal line (not shown) and a sensor cable 112 connected to the sensor signal line in the wiring holding unit 110 (FIG. 1). Further, the generated charges may be converted into a voltage signal by a circuit (not shown) inside the metal shell 120, and the converted voltage signal may be output to the outside.

A2. Configuration of power supply mechanism:
FIG. 3 is a cross-sectional view showing a configuration of an energization mechanism for energizing the heater 150 in the glow plug 100 of the first embodiment. In FIG. 3, for convenience of illustration, illustration of members not related to energization of the heater 150 is omitted.

  The heater 150 has an insulating part 152 formed of insulating ceramics and a conductive part 154 formed of conductive ceramics. The conductive portion 154 is embedded in the insulating portion 152 in a linear shape. The conductive portion 154 is formed by connecting two extending portions extending from the rear end side toward the front end side of the heater 150 at the front end portion of the heater 150. The conductive portion 154 has exposed portions 154 a and 154 b exposed on the outer periphery of the heater 150 at two locations, the rear end side and the front end side, of the heater 150.

  The exposed portion 154a on the distal end side of the conductive portion 154 is in contact with the heater holding portion 136 of the outer cylinder 130. As a result, the conductive portion 154 is electrically connected to the cylinder head via the outer cylinder 130 and the metal shell 120.

  The exposed portion 154b on the rear end side of the conductive portion 154 is in contact with the cylindrical ring 200 into which the heater 150 is press-fitted. On the rear end side of the ring 200, a base member 300 provided with a through hole 302 from the front end side toward the rear end side is press-fitted. As described above, the lead wire 400 is joined to the base member 300. Thus, the exposed portion 154 b on the rear end side of the conductive portion 154 is electrically connected to the lead wire 400 through the ring 200 and the base member 300.

  As described above, in the glow plug 100 of the first embodiment, the lead wire 400, the base member 300, the ring 200, the conductive portion 154, the outer cylinder 130, and the metal shell 120 are electrically connected in this order. Therefore, when a voltage is applied between the energization cable 114 (FIG. 1) connected to the lead wire 400 and the cylinder head, a current flows through the conductive portion 154 of the heater 150 and the heater 150 is heated.

  In the glow plug 100 of the first embodiment, the heater 150 is energized via the lead wire 400. As will be described later, the lead wire 400 can be made smaller by forming the lead wire 400 with a material having high electrical conductivity. Therefore, the inner diameter of the through hole of the sensor element 520 can be made smaller, and the cross-sectional area in the plane perpendicular to the axis O of the sensor element 520 can be made larger. Increasing the cross-sectional area of the sensor element 520 increases the load resistance of the sensor element 520. Further, when the cross-sectional area of the sensor element 520 is increased, an electrode (not shown) provided between the sensor element 520 and the insulating plates 510 and 530 can be made wider, and the sensor signal line can be more easily attached to the electrode. It becomes easy. Further, by reducing the wire diameter of the lead wire 400, the space that does not interfere with the lead wire 400 in the metal shell 120 can be made wider on the rear end side than the element stopper member 600. Therefore, it becomes easier to incorporate a circuit such as a signal processing circuit in the metal shell 120.

A3. Effects of the embodiment:
In the first embodiment, by attaching the lead wire 400 to the base member 300, electric power can be supplied to the heater 150 even if the length of the base member 300 in the axis O direction is shortened. Since the base member 300 is a member that transmits the displacement of the heater 150 with respect to the metal shell 120, it is possible to suppress the vibration of the glow plug 100 from being applied to the sensor element 520 by making the base member 300 shorter. Therefore, noise generated by vibration of the glow plug 100 can be further reduced.

  Furthermore, in the glow plug 100 of the first embodiment, the lead wire 400 is joined to the tip end side of the base member 300 through the through hole 302 provided in the base member 300. Therefore, when a force is applied to the lead wire 400, the stress is dispersed by the contact between the through hole 302 and the lead wire 400, and the stress applied to the joint portion is reduced. By reducing the stress applied to the joint portion, breakage of the joint portion between the lead wire 400 and the base member 300 can be suppressed.

  In order to reduce the stress applied to the lead wire 400, it is more preferable that the inner diameter of the through hole 302 is larger than the outer diameter of the lead wire 400. In this case, the shear stress applied to the lead wire 400 at the rear end of the base member 300 is reduced. Therefore, disconnection of the lead wire 400 can be suppressed. However, if the shear stress applied to the lead wire 400 can be reduced, the inner diameter of the through hole 302 is not necessarily larger than the wire diameter of the lead wire 500. For example, a chamfered portion similar to the front end side may be provided on the rear end side of the through hole 302. In general, the lead wire 400 only needs to be movable in the radial direction (that is, the cross-sectional direction of the through hole 302) with respect to the base member 300 at the rear end of the base member 300.

  On the other hand, when the difference (clearance) between the inner diameter of the through hole 302 and the lead wire 400 increases, the stress applied to the joint between the lead wire 400 and the base member 300 increases, and the lead wire 400 and the base member 300 There is a possibility that the joint portion of the material is broken. Therefore, the clearance can be determined by experiments, simulations, or the like in consideration of such characteristics.

  Table 1 below shows the result of evaluating the fracture position of the lead wire 400 by changing the wire diameter and the clearance in order to determine the clearance. The data in Table 1 shows that when nickel (Ni) is used as the lead wire 400 and the lead wire 400 (nickel wire) and the base member 300 are welded, a force in the rear end direction is applied to the lead wire 400. Indicates the position.

  As shown in Table 1, when the wire diameter was 0.5 mm and 0.8 mm, the lead wire 400 itself was broken when the clearance was 0.04 mm or less, and was broken at the joint portion when the clearance was 0.06 mm or more. On the other hand, when the wire diameter was 1 mm, the lead wire 400 itself was broken to a clearance of 0.1 mm. From this result, it was found that the clearance is preferably 0.04 mm or less when nickel having a wire diameter of 0.8 mm or less is used as the lead wire 400. On the other hand, it was found that when the wire diameter is 1 mm or more, the clearance can be increased to at least 0.1 mm.

A4. Assembling the heater assembly:
4 and 5 are explanatory views showing the assembly process of the heater assembly. FIG. 4 shows a process of joining the lead wire 400 to the base member 300. FIG. 5 shows a process of assembling the base member 300 to which the lead wire 400 is attached, the ring 200, and the heater 150.

  First, as shown in FIG. 4A, a wire 410 used as the lead wire 400 is prepared. As the wire 410, it is preferable to use a material having high electrical conductivity such as nickel or copper (Cu). Further, an alloy of these metals may be used. Note that iron (Fe) or stainless steel can also be used as the wire 410. However, it is more preferable to use a material having high electrical conductivity in that the diameter of the wire 410 can be further reduced. When nickel is used as the material of the wire 410, the wire diameter of the wire 410 is preferably in the range of 0.5 mm to 1.2 mm.

  Next, as shown in FIG. 4B, a rivet process is performed on the tip of the prepared wire 410 to form a large-diameter portion 412 having an outer diameter larger than that of the wire 410. The rivet process can be formed, for example, by pressing a tool having a flat end surface in the axial direction of the wire 410 while rotating the wire 410 in the circumferential direction around the axis. The large-diameter portion 412 can be formed by various methods such as press working and cutting in addition to rivet processing. The outer diameter of the large diameter portion 412 is appropriately set in consideration of the wire diameter of the wire 410 and the like. When a nickel wire having a wire diameter of 0.5 mm to 1.2 mm is used as the wire 410, the outer diameter of the large diameter portion 412 is set to be, for example, about 0.1 mm to 1.0 mm larger than the wire diameter.

  The wire 410 formed with the large diameter portion 412 is inserted into the through hole 302 of the base member 300. Specifically, as shown in FIG. 4C, the wire 410 having the large diameter portion 412 is inserted into the through hole 302 of the base member 300 attached to the collet 800 for welding. The collet 800 is a metal member in which a base 810 and a base member receiver 820 are formed. The pedestal 810 is provided with a through hole 812 for allowing the wire 410 to pass therethrough. The collet 800 is grounded for arc spot welding as will be described later.

  After the insertion of the wire 410, as shown in FIG. 4D, the large diameter portion 412 of the lead wire 400 and the base member 300 are joined by arc spot welding in an argon (Ar) atmosphere. In the example of FIG. 4D, the large diameter portion 412 of the lead wire 400 and the base member 300 are joined by arc spot welding, but other joining methods may be used. The large diameter portion 412 and the base member 300 can be joined by various methods such as resistance welding, ultrasonic welding, brazing, or soldering.

  In the first embodiment, the large diameter portion 412 and the base member 300 are joined by welding. Therefore, the brazing material or solder does not flow between the wire 410 and the through hole 302, and the wire 410 is not fixed on the rear end side of the base member 300. Thereby, even when a force is applied to the wire 410, the shear stress applied to the wire 410 on the rear end side of the base member 300 is reduced, and disconnection of the wire 410 is suppressed.

  In the example of FIG. 4, after insertion of the wire 410 shown in FIG. 4C, welding is performed as shown in FIG. After that, it is more preferable to apply pressure in the axial direction of the wire 410 (that is, the direction of the through hole 302) to the large diameter portion 412. In this case, it is more preferable to apply an impact force by hitting the large diameter portion 412 with a hammer or the like than applying a static pressure.

  In the example of FIG. 4, the wire 410 in which the large diameter portion 412 is formed is inserted into the through hole 302 of the base member 300, but the large diameter portion 412 is inserted after the wire 410 is inserted into the through hole 302. It may be formed.

  FIG. 5 shows a process of assembling a heater assembly from the base member 300 to which the lead wire 400 is bonded, the ring 200, and the heater 150 in the process shown in FIG. In the assembly process of the heater assembly of the first embodiment, as shown in FIG. 5A, first, the heater 150 is press-fitted into the ring 200, and the heater 150 and the ring 200 are fixed. Next, as shown in FIG. 5B, the base member 300 to which the lead wire 400 is bonded is press-fitted into the ring 200, and the base member 300 and the ring 200 are fixed. The fixing between the heater 150 and the ring 200 and the fixing between the base member 300 and the ring can also be performed by other methods such as brazing.

  In the example of FIG. 5, the heater assembly is assembled by pressing the heater 150 and the base member 300 into the ring 200 in this order. However, the press-fitting order into the ring is not necessarily limited to this. First, the base member 300 may be press-fitted into the ring 200, and then the heater 150 may be press-fitted into the ring 200.

  According to the assembly process of the heater assembly of the first embodiment, the large-diameter portion 412 is provided on the tip side of the wire 410, and the lead wire 400 and the base member 300 are welded to the large-diameter portion 412 and the base member 300. Are joined. In this way, by performing welding at the large diameter portion 412, it is possible to suppress the wire 410 from being thinned around the welded portion. Therefore, disconnection of the wire 410 can be suppressed.

B. Second embodiment:
FIG. 6 is an explanatory diagram showing the configuration of the glow plug of the second embodiment. In the second embodiment, as a power supply member for supplying electric power from the lead wire 400 to the heater 150, instead of the two members of the ring 200 and the base member 300, an integrally formed member 700 is used. This is different from the first embodiment shown in FIG. Other points are the same as in the first embodiment.

  FIG. 6A is a cross-sectional view showing the shape of the power feeding member 700 formed integrally. As shown in FIG. 6, the power supply member 700 is provided with a base portion 710 provided with a through hole 702 and a crown-shaped portion 720 corresponding to the ring 200.

  FIG. 6B is a cross-sectional view showing the configuration of the main part of the glow plug in the second embodiment. As shown in FIG. 6B, also in the second embodiment, the lead wire 400 is joined on the distal end side of the base portion 710 through the through hole 702. Then, the heater 150 (FIG. 3) is press-fitted into the crown portion 720 of the power supply member 700 to which the lead wire 400 is joined, thereby forming an energization path to the heater 150 as in the first embodiment. Further, since the displacement of the heater 150 is transmitted to the sensor element 520 through the power supply member 700, the pressure in the combustion chamber can be detected as in the first embodiment.

  Even in this case, the joint between the power supply member 700 and the lead wire 400 is provided on the distal end side of the base portion 710. Therefore, similarly to the first embodiment, the breakage of the lead wire 400 itself and the breakage of the joint portion between the lead wire 400 and the base portion 710 are suppressed. In addition, since the length of the power feeding member 700 in the direction of the axis O can be shortened, noise can be reduced.

The external view which shows the external appearance of the glow plug as one Example of this invention. Sectional drawing which shows the structure of the principal part of the glow plug of 1st Example. Sectional drawing which shows the structure of the electricity supply mechanism of the glow plug of 1st Example. Process drawing which shows the process of joining a lead wire to a base member. Process drawing which shows the process of assembling a base member, a ring, and a heater. Explanatory drawing which shows the structure of the glow plug of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Glow plug 110 ... Wiring holding part 112 ... Sensor cable 114 ... Current supply cable 120 ... Metal fitting 122 ... Engagement part 124 ... Screw part 130 ... Outer cylinder 132 ... Flange 134 ... Thin part 136 ... Heater holding part 140 ... Tip 142 ... cylindrical portion 144 ... tapered portion 150 ... heater 152 ... insulating portion 154 ... conductive portion 154a, 154b ... exposed portion 200 ... ring 300 ... base member 302 ... through hole 304 ... chamfered portion 312 ... tapered portion 314 ... fitting portion 316 ... Body part 318 ... Positioning part 400 ... Lead wire 410 ... Wire 412 ... Large diameter part 500 ... Lead wire 510,530 ... Insulating plate 520 ... Sensor element 600 ... Element stop member 610 ... Insertion part 620 ... Cylinder part 700 ... Power supply member 702 ... Through hole 710 ... Base part 720 ... Crown-shaped part 800 ... Let 810 ... pedestal 812 ... through hole 820 ... base member receiving

Claims (6)

A glow plug,
A tubular housing;
A heater provided at one end of the housing;
A sensor provided in the housing and detecting a displacement along a direction connecting the one end and the other end of the heater with respect to the housing;
A power supply member provided between the heater and the sensor in the housing, electrically connected to the heater, and mechanically transmitting displacement of the heater to the sensor;
A lead member disposed in the housing from the power supply member toward the other end than the sensor, and supplying electric power from an external power source to the heater via the power supply member,
The power supply member has a through hole penetrating from the one end side to the other end side,
The lead member inserted into the through hole and the power supply member are joined on the one end side of the through hole of the power supply member. The glow plug according to claim 1,
The lead member is movable in a cross-sectional direction of the through hole on the other end side of the through hole. A glow plug according to claim 1 or 2, wherein
The glow plug, wherein the lead member has an outer diameter on the one end side larger than a diameter of the through hole. The glow plug according to any one of claims 1 to 3,
The joint between the lead member and the power supply member is made by welding. Glow plug. A method of manufacturing a glow plug,
The one end and the other end of the heater with respect to the housing are electrically connected to a heater provided at one end of the housing and disposed between the heater and the sensor in the housing. A power supply member that mechanically transmits a displacement along a direction connecting the sensor to the sensor, the power supply member having a through hole from the one end side to the other end side; and
Forming the one end portion side of the lead member inserted through the through hole as a large diameter portion having an outer diameter larger than the diameter of the through hole;
And a step of joining the large diameter portion and the power feeding member on the one end side of the through hole. A method for manufacturing a glow plug according to claim 5,
The method of manufacturing a glow plug, wherein the joining of the large diameter portion and the power supply member is performed by welding.

Images