JP2010216738A - Sheath heater, glow plug, and method of manufacturing sheath heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheath heater, a blow plug, and a method of manufacturing the sheath heater capable of securing sufficient connection force of a resistance wire coil 6 to a tip recessed section 5c of a power distribution terminal 5. <P>SOLUTION: This sheath heater 2 includes a cylindrical metallic sheath tube 4 closed at its tip 4a, the power distribution terminal 5 having a tip section 5a inserted to a rear end section of the tube 4, and having the tip recessed section 5c on its tip face, the resistance wire coil 6 having a tip section 6a connected to a tip of the sheath tube 4 and a rear end section 6b fitted to the tip recessed section 5c of the power distribution terminal 5, and insulating powder 7 filled in the sheath tube 4, and is constituted by reducing a diameter of the sheath tube 4 sealed by a sealing member 8, by swaging. An outer peripheral part of the power distribution terminal 5 corresponding to the tip recessed section 5c has a thin section 5i, and a thick section 5d having a thickness more than that of the thin section 5i and projecting outward, and one of an inner diameter of the thin section 5i and an inner diameter of the thick section 5d is smaller than the other in this sheath heater 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheath heater for heating an object to be heated such as gas or liquid, a glow plug of a diesel engine, and a method for manufacturing a sheath heater.

The structure of a conventional sheath heater will be described with reference to FIGS.
As is well known, the glow plug 100 is for preheating a diesel engine. As shown in FIGS. 10A and 10B, the radially outer side of the sheath heater 101 is a cylindrical metal shell 102. Surrounded by.

  The sheath heater 101 includes a metal sheath tube 103, a column-shaped energizing terminal 104 having a distal end portion 104a inserted on the rear end side of the sheath tube 103, a resistance wire coil 105 disposed in the sheath tube 103, An insulating powder 106 filled in the sheath tube 103 and a sealing member 107 that seals the opening of the rear end 103b of the sheath tube 103 are provided. The sheath tube 103 has a cylindrical shape that extends in the axial direction, the front end 103a is closed, and the rear end 103b is opened. The energizing terminal 104 has a tip recess 104c on the tip surface 104b. Further, the resistance wire coil 105 has a distal end portion 105 a connected to the distal end 103 a of the sheath tube 103 and a rear end portion 105 b fitted into the distal end concave portion 104 c of the energizing terminal 104.

In the resistance coil 105, the rear end portion 105b is inserted into the front end concave portion 104c of the energizing terminal 104 as shown in FIG. 11A, and in this state, the periphery of the front end concave portion 104c is crimped as shown in FIG. It is attached (refer to patent document 1) or attached by welding.
And the sheath heater 101 arrange | positions the resistance wire coil 105 attached to the electricity supply terminal 104 in the sheath tube 103, is filled with the insulating powder 105, and after sealing the back end 103b of the sheath tube 103 with the sealing member 106, The diameter is reduced to a predetermined diameter by swaging.

JP 2000-240943 A (paragraph 0011, last line)

In the swaging of the sheath tube 103, a restriction is applied from the rear end 103b to the front end 103a. Therefore, during the swaging, the resistance coil 105 has a force of an axial component from the rear end 103b of the sheath tube 103 toward the front end 103a. Works. Therefore, the resistance wire coil 105 receives a tensile force in a direction away from the energizing terminal 104 during swaging.
Therefore, if the connection between the tip recess 104c of the energizing terminal 104 and the resistance wire coil 105 by caulking or welding is insufficient, in the worst case, the resistance wire coil 105 is pulled out from the tip recess 104c of the energizing terminal 104, resulting in poor connection. There is a risk.

  On the other hand, if the caulking or welding is strengthened in order to prevent the resistance wire coil 105 from falling off, the local deformation of the resistance wire coil 105 at the caulking or welding portion becomes large. Alternatively, when the welded portion is in the vicinity of the tip of the tip recess 104c, there is a problem that the resistance wire coil 105 bends greatly starting from the tip of the tip recess 104c, that is, the tip of the energizing terminal 104. Such bending of the resistance wire coil 105 causes a short circuit between the sheath tube 103 and the resistance wire coil 105 and variation in energization performance.

  Also, if the crimped or welded portion is at the back of the tip recess 104c, the resistance wire coil 105 is guided by the inner periphery of the tip from the crimped or welded portion of the tip recess 104c. Although bending can be prevented, the contact between the inner periphery of the tip of the tip recess 104c and the resistance wire coil 105 is unstable. As a result, the starting point of the electrical resistance varies, resulting in variations in resistance values and unstable current-carrying performance. Another problem occurs.

  The present invention has been made in view of the above, and an object of the present invention is to provide a sheath heater, a glow plug, and a method for manufacturing the sheath heater that can sufficiently secure a coupling force to the tip recess of the energization terminal of the resistance wire coil.

  In order to achieve the above object, the present invention provides a cylindrical metal sheath tube extending in the axial direction, closed at the tip, and opened at the rear end, and a tip inserted into the rear end of the sheath tube. A column-shaped energizing terminal having a leading end recess on the leading end surface, a leading end disposed in the sheath tube and connected to the leading end of the sheath tube, and a rear end fitted into the leading end recess of the energizing terminal A sheath wire in a state of being sealed with the sealing member, comprising a resistance wire coil having a portion, an insulating powder filled in the sheath tube, and a sealing member for sealing a rear end of the sheath tube In the sheath heater formed by reducing the diameter to a predetermined diameter by swaging, the outer peripheral portion of the energization terminal corresponding to the outside of the tip recessed portion has a thin portion and a thickness larger than the thin portion and outside the thin portion. In It includes a thick portion that has issued, and one of the inner diameter and the inner diameter of the thick portion of the thin portion to provide a sheath heater which is smaller than the other.

  In the sheath heater, either the thick part or the thin part may be provided at the tip of the energizing terminal.

  Furthermore, in the sheath heater, the resistance wire coil is provided with a large-diameter portion having a larger outer diameter than the small-diameter portion on the rear end side of the small-diameter portion having the smallest inner diameter among the tip recesses. Good.

  In addition, the present invention provides a glow plug that includes the sheath heater and a cylindrical metallic shell that houses the sheath heater, and a distal end side of the sheath heater projects from the distal end of the metallic shell.

  In addition, the present invention has a cylindrical metal sheath tube extending in the axial direction, closed at the tip, and opened at the rear end, and a front end inserted into the rear end of the sheath tube. A resistance wire having a column-shaped energizing terminal having a tip recess, a tip disposed in the sheath tube and connected to the tip of the sheath tube, and a rear end fitted in the tip recess of the current terminal A method for manufacturing a sheath heater comprising a coil, an insulating powder filled in the sheath tube, and a sealing member for sealing the rear end of the sheath tube, and energization corresponding to the outside of the tip recess Providing a thin-walled portion and a thick-walled portion having a thickness larger than the thin-walled portion and an outer diameter larger than the thin-walled portion on the outer periphery of the terminal; The process of fitting in the recess and connecting Connecting the distal end of the resistance wire coil to the inner surface of the distal end of the sheath tube; filling the sheath tube with insulating powder; and sealing the rear end opening of the sheath tube with a sealing member; And a swaging step of reducing the inner diameter of one of the thin part and the thick part to be smaller than the other while reducing the diameter of the sheath tube sealed with the sealing member to a predetermined diameter. A manufacturing method is provided.

  In the manufacturing method of the sheath heater, either the thick part or the thin part may be provided at the tip of the energizing terminal.

  Furthermore, in the method of manufacturing the sheath heater, the step of fitting and connecting the rear end of the resistance wire coil to the tip recess of the energization terminal may be performed by press-fitting the tip of the resistance wire coil into the tip recess of the energization terminal.

  When swaging the sheath tube, the thin part with low rigidity is preferentially reduced in diameter through the layer of insulating powder while the processing rate is low, and the reduction ratio during swaging of the thin part becomes larger than the others. . As a result, the inner diameter of the thin wall portion can be made smaller than the inner diameter of the thick wall portion. On the other hand, when the processing rate is increased, the diameter reduction rate of the thin wall portion is blunted due to an increase in resistance for narrowing the resistance wire coil, and conversely, there is a thick wall portion that protrudes outward from the thin wall portion and has a narrow gap between the sheath tube. It is processed preferentially, and the diameter reduction rate during swaging of the thick-walled portion is greater than others. As a result, the inner diameter of the thick part can be made smaller than the inner diameter of the thin part. This is because the thick part has a thinner insulating powder layer between the sheath and the thin tube than the thin part, so that the swaging force is not dispersed, and the swaging force acts more strongly on the thick part. Because it does.

  As described above, the present invention is arranged on the outer peripheral portion of the energizing terminal corresponding to the outer side of the tip recess so that the thin portion and the gap between the thin portion and the sheath tube are narrower than the thin portion. Since both the protruding thick part is provided, the inner diameter of either the thick part or the thin part is selectively reduced according to the processing rate of swaging, and it becomes a state equivalent to being crimped. . Accordingly, swaging increases the coupling force between the tip recess of the energizing terminal and the resistance wire coil. In addition, at this time, since the resistance wire coil is fixed to the center position of the sheath tube by the insulating powder, there is no bending of the resistance wire coil that may occur when strong caulking is performed before mounting on the sheath tube. Therefore, it is possible to sufficiently ensure the connection reliability between the energization terminal and the resistance wire coil after the sheath tube is swaged.

  Moreover, since it is preferable that the inner diameter of the tip side of the tip recess is the smallest, when the swaging rate is small, the thin portion is provided at the tip of the current-carrying terminal, while when the swaging rate is large, It is preferable to provide a thick portion at the tip of the energizing terminal. As a result, the tip of the tip recess sags and comes into contact with the resistance wire coil, and the contact portion becomes the starting point of electric resistance, so that the resistance value of the resistance wire coil is stabilized. Also, when the resistance wire coil is caulked in the tip recess by swaging, the resistance wire coil itself is also fixed and pressurized via the insulating powder, so that the resistance wire coil is caused by the caulking force at the time of diameter reduction. Deformation and bending can be prevented, and short circuit failure and variation in resistance value can be prevented.

  In addition, by pressing the tip of the resistance wire coil into the tip recess in the sheath heater so that it can be temporarily fixed, it is possible to prevent the tip recess and the center of the resistance wire coil from being misaligned during caulking and welding processes. it can. In addition, in the state where the tip of the resistance wire coil is press-fitted into the tip recess of the energizing terminal and temporarily fixed, the inner surface of the tip recess and the outer surface of the resistance coil are in close contact with each other, so that the sheath tube is filled with insulating powder However, it is difficult for the insulating powder to enter between the tip recess and the resistance wire coil. Accordingly, the contact between the tip recess and the resistance wire coil is improved, which is effective in stabilizing the resistance value of the resistance wire coil.

(A) is a longitudinal cross-sectional view of a glow plug, (b) is an enlarged view of Z1 part of Fig.1 (a). (A)-(d) is a longitudinal cross-sectional view of the principal part explaining the manufacturing process of a sheath heater. It is the XX sectional view taken on the line of FIG. In Embodiment 1, it is a longitudinal cross-sectional view which shows the state after swaging when a swaging process rate is large. (A), (b) is the longitudinal cross-sectional view of the principal part explaining the manufacturing process of the sheath heater which concerns on Embodiment 2. FIG. In Embodiment 2, it is a longitudinal cross-sectional view which shows the state after swaging when a swaging process rate is large. (A), (b) is a longitudinal cross-sectional view which shows the front-end | tip part of the electricity supply terminal which concerns on another form. FIG. 9A is a longitudinal sectional view showing the tip portion of the energization terminal, and FIG. 8B is an enlarged view of a Z2 portion in FIG. (A), (b) is a longitudinal cross-sectional view of the principal part explaining the manufacturing process of the sheath heater which concerns on another form. A conventional glow plug is shown, in which (a) is a longitudinal sectional view of the glow plug, and (b) is an enlarged view of a portion Z3 in FIG. 10 (a). (A)-(c) is a longitudinal cross-sectional view of the principal part explaining the manufacturing process of the conventional sheath heater.

[Embodiment 1]
Embodiment 1 of the present invention will be described below with reference to FIGS. 1A is a longitudinal sectional view of the glow plug, FIG. 1B is an enlarged view of the Z1 portion of FIG. 1A, and FIGS. 2A to 2D are diagrams for explaining the manufacturing process of the sheath heater. FIG. 3 is a sectional view taken along line XX of FIG. 2C, and FIG. 4 is a longitudinal sectional view showing a state after swaging when the swaging rate is large.

  As is well known, the glow plug 1 is for preheating a diesel engine (not shown). As shown in FIG. 1A, the radially outer side of the sheath heater 2 is surrounded by a cylindrical metal shell 3. Do it.

[Sheath heater]
The sheath heater 2 is disposed in the sheath tube 4, a sheath tube 4 made of metal (for example, stainless alloy or nickel alloy), a column-shaped energization terminal 5 having a tip portion 5 a inserted on the rear end 4 b side of the sheath tube 4. A resistance wire coil 6, an insulating powder 7 filled in the sheath tube 4, and a sealing member 8 that seals the rear end 4 b of the sheath tube 4. The sheath tube 4 extends in the axial direction, has a cylindrical shape with a front end 4a closed and a rear end 4b opened. The energizing terminal 5 has a tip recess 5c on the tip surface 5b and a thick part 5d and a thin part 5i on the outer periphery of the tip. The thick part 5d is thicker than the thin part 5i, and protrudes outward from the thin part 5i. Furthermore, the resistance wire coil 6 has a distal end portion 6 a connected to the distal end of the sheath tube 4 and a rear end portion 6 b fitted into the distal end recessed portion 5 c of the energizing terminal 5.

  As shown in FIG. 1B, the tip recess 5c of the energizing terminal 5 has a small diameter portion 5e at a position corresponding to the thick portion 5d, that is, at the tip of the tip recess 5c in this embodiment, A large-diameter portion 5f having an inner diameter larger than that of the small-diameter portion 5e is provided on the rear end side in the axial direction from the small-diameter portion 5e. The rear end portion 6b of the resistance wire coil 6 fitted into the tip recess portion 5c includes a constricted rear end diameter small portion 6c located at the small diameter portion 5e of the tip recess portion 5c and a large diameter portion of the tip recess portion 5c. The front end recessed portion 5c of the energizing terminal 5 and the resistance wire coil have a rear end large diameter portion 6d located at 5f, and the difference in diameter between the rear end large diameter portion 6d of the resistance wire coil 6 and the small diameter portion 5e of the front end recessed portion 5c. 6 is firmly bonded.

  On the other hand, as shown in FIG. 2A, the energization terminal 5 before the resistance wire coil 6 is fitted has a round hole-shaped tip recess 5c drilled from the center of the tip surface 5b to the rear, and a tip recess. A thick portion 5d provided at the front end of the outer wall portion 5c and a thin portion 5i provided on the rear end side of the thick portion 5d and having a smaller thickness than the thick portion 5d. The inner diameter of the thick part 5d and the thin part 5i is the same, but the outer diameter of the thick part 5d is larger than the outer diameter of the thin part 5i. The inner diameter of the tip recess 5 c is substantially the same as the outer diameter of the rear end 6 b of the resistance wire coil 6.

[Method for manufacturing sheath heater]
Next, a method for manufacturing the sheath heater 2 will be described.
First, in the process of manufacturing the energization terminal 5, the thick part 5d and the thin part 5i are integrally formed in the outer peripheral part of the front-end | tip recessed part 5c.
Next, the rear end portion 6b of the resistance wire coil 6 is fitted into the front end concave portion 5c of the energizing terminal 5 as shown in FIG. 2B, and the intermediate portion on the outer periphery of the front end concave portion 5c as shown in FIG. The energizing terminal 5 and the resistance wire coil 6 are coupled by caulking. In this case, the degree of caulking may be lighter than before.

  Next, the resistance wire coil 6 is inserted into the inside of the sheath tube 4 from the opening of the rear end 4b of the sheath tube 4, and the distal end portion 6a of the resistance wire coil 6 and the distal end 4a of the sheath tube 4 are connected by welding or the like. In the state of FIG. 2C in which the resistance wire coil 6 is arranged in the sheath tube 4 in this way, the thick portion 5d of the energizing terminal 5 protrudes into the gap 9 between the sheath tube 4 and the energizing terminal 5. The gap 9 is narrower than other portions.

  Next, the insulating powder 7 is filled from the opening of the rear end 4 b of the sheath tube 4, the insulating powder 7 is slightly pressurized in the axial direction, and then the rear end 4 b of the sheath tube 4 is sealed with the sealing member 8. And this sheath tube 4 is diameter-reduced by well-known swaging from the rear end 4b to the front-end | tip 4a. At this time, since the force also reaches the energizing terminal 5 and the resistance wire coil 6 through the insulating powder 7, they are also reduced in diameter, but at that time, if the processing rate of swaging is low, the thick portion The thin part 5i having a thickness smaller than 5d and lower rigidity is selectively reduced in diameter, and as shown in FIG. 2D, the inner diameter of the thin part 5i is smaller than the inner diameter of the thick part 5d. Become. As a result, the small diameter part 5e is formed in a part of the thin part 5i of the energizing terminal 5, and the large diameter part 5f is formed behind the small diameter part 5e. The deformation also deforms the rear end portion 6b of the resistance wire coil 6 to form a rear end small diameter portion 6c and a rear end large diameter portion 6d, so that the front end concave portion 5c of the energizing terminal 5 and the resistance wire coil 6 are firmly formed. Join.

  Further, when the swaging is further advanced and the processing rate is increased, the diameter reduction rate of the thin portion 5i is decreased due to an increase in resistance for narrowing the resistance wire coil 6. On the other hand, the thick portion 5d has a narrower gap 9 with the inner wall of the sheath tube 4 than the other portions, and there is less insulating powder 7 interposed between the thick portion 5d and the thick portion 5d. Works relatively strongly. Therefore, the ratio of the reduced diameter of the thick part 5d is larger than that of the thin part 5i. Therefore, since the thick portion 5d is in a state equivalent to being selectively caulked by the swaging force, the inner diameter of the thick portion 5d is smaller than the inner diameter of the thin portion 5i. As a result, the periphery of the front end surface 5b of the energizing terminal 5 is sunk to form a small diameter portion 5e and a large diameter portion 5f in the front end recess 5c as shown in FIG. The deformation also deforms the rear end portion 6b of the resistance wire coil 6 to form a rear end small diameter portion 6c and a rear end large diameter portion 6d, so that the front end concave portion 5c of the energizing terminal 5 and the resistance wire coil 6 are firmly formed. Join.

[Main metal fittings]
Returning to FIG. 1A, the metal shell 3 surrounds the radially outer side of the sheath tube 4. A bush-shaped insulating ring 10 is fitted into the rear end opening of the metal shell 3, and the rear end portion 5 g of the energizing terminal 5 of the sheath heater 2 is supported by the insulating ring 10 at the center of the metal shell 3.
On the other hand, an inward protruding portion 11 is formed on the inner wall slightly inward from the front end of the metal shell 3, and the protruding portion 11 supports the sheath tube 4 of the sheath heater 2 in a tightly fitted state.

In addition, a tool engaging portion 12 in the form of a hexagonal bolt is provided on the outer periphery of the rear end of the metal shell 3, and a male screw 13 for mounting on a diesel engine is formed on the front end side of the outer periphery.
Further, a screw portion 14 for connecting a power cable (not shown) is formed at a portion of the rear end portion 5g of the energizing terminal 5 that protrudes from the rear end of the metal shell 3 to the outside. The insulating ring 10 is pressed by a round nut 15 that is screwed onto the insulating ring 10.

[Embodiment 2]
5 (a), 5 (b), and 6 show a second embodiment and are longitudinal sectional views of main parts for explaining the manufacturing process of the sheath heater.
The second embodiment is common to the first embodiment in that a thick portion 5d and a thin portion 5i are provided from the tip at a portion corresponding to the outside of the tip recess 5c. However, as shown in FIG. The thin portion 5i is different in that it is thinner than its rear side. The second embodiment is also different in that the rear end 6b of the resistance wire coil 6 is press-fitted into the front end recess 5c without being crimped in advance before swaging. In addition, the same code | symbol is attached | subjected to the part same as Embodiment 1, and description is abbreviate | omitted.

Even when the thin portion 5i is made thinner as in the second embodiment, when the processing rate of swaging is small, the thin portion 5i having relatively low rigidity is selectively used as shown in FIG. The diameter is smaller than the others. On the other hand, when the processing rate of swaging is large, as shown in FIG. 6, the thick portion 5d having a relatively narrow gap 9 with the sheath tube 4 is selectively reduced in diameter compared to the others.
As described above, although the portion to be reduced in diameter changes depending on the processing rate of swaging, since the diameter is selectively reduced as compared with the case where the entire diameter is reduced uniformly, either the thick portion 5d or the thin portion 5i is selectively selected. Even when the diameter is reduced, the bonding strength between the resistance wire coil 6 and the energizing terminal 5 can be improved. Therefore, the same effect as in the first embodiment can be obtained.

As mentioned above, although this invention was demonstrated about Embodiment 1 and 2, of course, this invention is not limited to the said embodiment.
For example, in the first and second embodiments, the sheath heater 2 has been described as an example of application to the glow plug 1, but other than that, the present invention can be applied to any heater that heats an object to be heated such as a water heater or the like.

  In the first and second embodiments, the position of the flange member 5d is the tip of the tip recess 5c, but the position of the thick portion 5d is, for example, as shown in FIG. You may make it back behind the thin part 5i among outer parts. Such a form is particularly effective when the processing rate by swaging is small. That is, when the swaging rate is small, the thin-walled portion 5i that is located on the distal end side and has low rigidity is selectively reduced in diameter, and therefore, as shown in FIG. A small-diameter portion 5e is formed at a position corresponding to the thin-walled portion 5i on the front end side, and a large-diameter portion 5f having a larger inner diameter than the small-diameter portion 5e is formed at a position corresponding to the thick-walled portion 5d on the rear end side. The deformation also deforms the rear end portion 6b of the resistance wire coil 6 to form a rear end small diameter portion 6c and a rear end large diameter portion 6d, so that the front end concave portion 5c of the energizing terminal 5 and the resistance wire coil 6 are firmly formed. Join. When the resistance wire coil 6 is coupled at the distal end side of the distal end recess 5 c of the energization terminal 5 in this way, the distal end of the energization terminal 5 becomes the start end of the resistance wire coil 6. Variation, that is, variation in resistance value can be reduced.

  In the first embodiment, the rearward surface 5h of the thick portion 5d is straight in the direction orthogonal to the axis of the sheath tube 4, but as shown in FIGS. 8 (a) and 8 (b) The rearward surface 5h of the part 5d may be a truncated cone-shaped tapered surface. In such a case, part of the axial component force acting when swaging is performed from the rear end side to the distal end side of the sheath tube 4 is converted into a radial component force by the inclination of the tapered surface. Therefore, the thick portion 5d of the energization terminal 5 can be tightened with a stronger force.

In the first embodiment, the rear end 6b of the resistance wire coil 6 is fitted into the front end recess 5c of the energization terminal 5, and then the outer periphery of the front end recess 5c is crimped. The outer diameter of the portion 6b is formed slightly larger than the inner diameter of the tip recess 5c of the energizing terminal 5, and the rear end portion 6b of the resistance wire coil 6 is press-fitted into the tip recess 5c of the energizing terminal 5 as shown in FIG. Then, it may be temporarily fixed and placed in the sheath tube 4 without caulking as it is, and the sheath tube 4 may be swaged as described above. By doing so, the center of the tip recess 5c and the resistance wire coil 6 that can occur in the caulking process can be prevented, and the inner surface of the tip recess 5c and the outer surface of the resistance wire coil 6 are in close contact with each other without any gap. Since the insulating powder 7 is less likely to enter between the resistance wire coil 6 and the resistance wire coil 6, the contact between the tip recess portion 5 c and the resistance wire coil 6 is improved.
Even in this case, when the swaging processing rate is large, as shown in FIG. 9B, the thick portion 5d may be selectively reduced in diameter, while the swaging processing rate may be small. In this case, the thin part 5i is selectively reduced in diameter. In any case, since the fitting force at the selectively reduced diameter portion can be increased, the thickness of the outer peripheral portion of the tip recess portion 5c is uniform, and the resistance wire is compared with the case where the diameter is reduced equally. The falling off of the coil 6 can be prevented.

  In the first and second embodiments, the protruding portion of the thick portion 5d is integrated with the energizing terminal 5 or the sheath tube 4. However, as a separate component, an annular member is fitted to the outer periphery of the tip of the energizing terminal, thereby increasing the thickness. The part 5d may be formed.

DESCRIPTION OF SYMBOLS 1 ... Glow plug 2 ... Sheath heater 3 ... Metal fitting 4 ... Sheath tube 4a ... Tip 4b ... Rear end 5 ... Current supply terminal 5a ... Tip part 5c ... Tip recessed part 5d ... Thick part 5e ... Small diameter part 5f ... Large diameter part 5i ... Thin part 6 ... Resistance wire coil 6a ... Front end part 6b ... Rear end part 7 ... Insulating powder 8 ... Sealing member 9 ... Gap

Claims (7)

A cylindrical metal sheath tube extending in the axial direction, closed at the front end, and opened at the rear end;
A columnar current-carrying terminal having a distal end portion inserted into a rear end portion of the sheath tube and having a distal end concave portion on the distal end surface;
A resistance coil that is disposed in the sheath tube and has a distal end portion connected to the distal end of the sheath tube, and a rear end portion fitted in a distal end concave portion of the energization terminal;
Insulating powder filled in the sheath tube;
A sealing member for sealing the rear end of the sheath tube,
In the sheath heater formed by reducing the diameter of the sheath tube sealed with the sealing member to a predetermined diameter by swaging,
The outer peripheral portion of the energizing terminal corresponding to the outside of the tip recess is
Thin part,
A thicker portion having a larger thickness than the thinned portion and protruding outward from the thinned portion,
One of the inner diameter of the said thin part and the inner diameter of the said thick part is smaller than the other, The sheath heater characterized by the above-mentioned.   The sheath heater according to claim 1, wherein one of the thick part and the thin part is provided at a tip of an energizing terminal.   The resistance wire coil is provided with a large-diameter portion having a larger outer diameter than the small-diameter portion on the rear end side of the small-diameter portion having the smallest inner diameter among the tip concave portions. Or the sheath heater of 2. The sheath heater according to any one of claims 1 to 3,
A cylindrical metal shell for housing the sheath heater;
A glow plug characterized in that the distal end side of the sheath heater protrudes from the distal end of the metal shell. A cylindrical metal sheath tube extending in the axial direction, closed at the front end, and opened at the rear end;
A columnar current-carrying terminal having a distal end portion inserted into a rear end portion of the sheath tube and having a distal end concave portion on the distal end surface;
A resistance coil that is disposed in the sheath tube and has a distal end portion connected to the distal end of the sheath tube, and a rear end portion fitted in a distal end concave portion of the energization terminal;
Insulating powder filled in the sheath tube;
A sealing member for sealing a rear end of the sheath tube, and a method for manufacturing a sheath heater,
On the outer periphery of the energizing terminal corresponding to the outside of the tip recess, a step of providing a thin portion and a thick portion having a larger thickness than the thin portion and a larger outer diameter than the thin portion;
A step of fitting the rear end portion of the resistance wire coil into a leading end concave portion of the energizing terminal, and connecting;
Connecting the distal end of the resistance wire coil to the inner surface of the distal end of the sheath tube;
Filling the inside of the sheath tube with insulating powder, and sealing the rear end opening of the sheath tube with a sealing member;
While reducing the diameter of the sheath tube sealed with the sealing member to a predetermined diameter, a swaging step of making the inner diameter of either the thin part or the thick part smaller than the other,
A method for manufacturing a sheath heater, comprising:   6. The method of manufacturing a sheath heater according to claim 5, wherein either the thick part or the thin part is provided at a tip of the energizing terminal.   The step of fitting and connecting the rear end of the resistance wire coil to the tip recess of the energization terminal is to press-fit the tip of the resistance wire coil into the tip recess of the energization terminal. 6. A method for manufacturing a sheath heater according to 6.

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