JP2019184087A - heater - Google Patents

Abstract

To provide a heater capable of restricting that an electric heating element is influenced by oxidative consumption caused by passing of a sheath pipe through the heater while assuring water-tightness between the sheath pipe and a housing when a thin-wall part arranged at the housing and the sheath pipe are connected to each other.SOLUTION: This invention relates to a heater comprising a cylindrical sheath pipe extending in an axial line direction and closed at its extremity end, an electric heating element heated by electrical energy and a cylindrical housing inserting a rear end side of the sheath pipe into a cylindrical hole of itself. The housing includes a main body part, and a cylindrical thin wall part thinner than a thickness of the main body part arranged at an extremity end side rather than the main body part to overlap against the sheath pipe in an axial line direction, there is provided a melting part formed by laser welding to the thin wall part and the sheath pipe over its entire circumference, and a thickness of the thin-wall part at an interface of the outer surfaces of the thin-walled part between a non-melted part adjacent to the melting part and the melting part is thinner than a thickness of said sheath pipe.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heater used as a liquid heating source.

  The glow plug is usually used as an auxiliary heat source for an internal combustion engine such as a diesel engine using a compression ignition system. This glow plug usually has a bottomed cylindrical sheath tube whose front end is closed and its rear end is open, and a heating element that is disposed inside the sheath tube and generates heat when energized. Further, the glow plug has a cylindrical housing that holds the rear end side of the sheath tube through its own cylindrical hole while projecting the distal end side of the sheath tube.

By the way, as a use of a glow plug, in recent years, it is also known that it is used not only as an auxiliary heat source of an internal combustion engine but also as a liquid heating source. Hereinafter, a glow plug used as a liquid heating source is referred to as a heater. For example, by exposing the sheath tube of the heater to a liquid such as oil or washer liquid used in an internal combustion engine, the heat generated by the heating element can be conducted to the liquid through the sheath tube and the liquid can be heated.
When the heater is used as a liquid heat source, water tightness between the sheath tube and the housing is important in order to prevent liquid from entering the housing. Therefore, it is known to laser weld the sheath tube and the housing in the circumferential direction. (See Patent Documents 1 and 2)

JP 2010-203763 A Special table 2012-509542 gazette

In Patent Literature 1 and Patent Literature 2, as a housing, a main body portion provided with a male screw portion and a tool engaging portion, and a portion (hereinafter referred to as a thickness portion provided below the main body portion and thinner than the main body portion). And the thin-walled portion and the sheath tube are laser-welded over the circumferential direction.
However, since the thickness of the sheath tube of the heater is very thin in consideration of thermal conductivity, the sheath tube and the housing are simply provided by providing a thin wall portion in the housing as in Patent Document 1 and Patent Document 2. There is a possibility that it cannot be bonded well. Specifically, the melted portion formed between the thin-walled portion and the sheath tube does not sufficiently enter the sheath tube, and the bonding strength between the sheath tube and the housing is not sufficient, and as a result, the water tightness between the housing and the sheath tube. However, there was a possibility that could not be secured. On the other hand, if the welding conditions are changed (for example, the laser output is increased, etc.) so that the melted portion sufficiently enters the sheath tube, the melted portion penetrates the sheath tube, and a hole is formed in the sheath tube. As a result, the heating element disposed in the sheath tube may be oxidized and consumed.

  The present invention has been made to solve the above-described conventional problems. In joining the thin wall portion provided in the housing and the sheath tube, the sheath tube and the housing are secured while ensuring the water tightness. An object of the present invention is to provide a heater capable of suppressing the exhaustion of the heating element through the tube.

  The heater according to the present invention includes a cylindrical sheath tube extending in the axial direction and having a closed end, a heating element that is disposed in the sheath tube and generates heat when energized, and a rear end side of the sheath tube is formed in its own cylindrical hole. A cylindrical housing that is inserted into the body, the housing being disposed on the distal end side of the body portion and overlapping the sheath tube in the axial direction. A heater that is provided with a melted portion formed by laser welding over the entire circumference of the thin-walled portion and the sheath tube. The thickness of the thin-walled portion at the boundary of the outer surface of the thin-walled portion between the non-melting portion adjacent to the melted portion is smaller than the thickness of the sheath tube.

  According to the heater of this form, the thickness of the thin portion is made thinner than the thickness of the sheath tube. Thereby, the fusion | melting part provided in a sheath pipe | tube can be adjusted to a suitable magnitude | size. As a result, it is possible to ensure the watertightness of the sheath tube and the housing, and it is possible to suppress the heating element from being oxidized and consumed through the sheath tube.

Moreover, as the “boundary of the outer surface of the thin part between the non-melting part and the melting part adjacent to the melting part”, the boundary between the non-melting part and the melting part provided on the tip side of the melting part among the thin parts ( In addition to the front end side boundary, the boundary between the non-melted portion and the melted portion provided on the rear end side of the melted portion in the thin portion (hereinafter also referred to as the rear end side boundary) can be given.
Furthermore, “the thickness of the thin portion at the boundary is thinner than the thickness of the sheath tube” means that the thickness of the thin portion at the front end side boundary is thinner than the thickness of the sheath tube and the thickness of the thin portion at the rear end side boundary is the sheath. A form thinner than the thickness of the tube is mentioned. In addition, when both the front end side boundary and the rear end side boundary exist, it is sufficient that the thickness of one of the boundaries and the thickness of the sheath tube satisfy the above-described relationship, and more preferably, It is only necessary that the thickness and the thickness of the sheath tube have the above relationship. On the other hand, when only one of the front end side boundary and the rear end side boundary exists, the thickness of the existing one boundary and the thickness of the sheath tube need only be in the above relationship.

  In the heater of the present invention, it is preferable that the melting portion is provided in a position separated from the main body portion in the thin portion. If a melted part is formed at a position adjacent to the main body part in the thin-walled part, when forming the melted part by welding, heat during welding is easily conducted to the main body part, and it is difficult to obtain a good melted part shape. Become. On the other hand, when the melted part is formed in a thin part spaced apart from the main body part, heat during welding is hardly conducted to the main body part, and a good melted part shape can be obtained.

  In the heater of the present invention, it is preferable that an axial distance between a rear end of the melting portion and a front end of the main body is greater than 1 mm. By separating the rear end of the melted portion from the front end of the main body more than 1 mm, heat at the time of welding becomes more difficult to conduct to the main body, and cracks generated in the melted portion (hereinafter also referred to as solidification cracks) are generated. This can be suppressed.

In the heater of the present invention, it is preferable that a press-fitting part in which the sheath tube is press-fitted is provided in at least a part of the thin part. As described above, by providing the press-fitting portion in the thin portion, the shaft of the sheath tube and the thin portion can be substantially aligned with each other, and the axial displacement of the sheath tube and the thin portion can be suppressed. As a result, the melted portion formed in the thin-walled portion can obtain a substantially uniform and good shape in the circumferential direction.
The press-fitting part may be provided in a part of the thin part or may be provided in the entire thin part.

Moreover, it is preferable that the heater of this invention is provided so that the said fusion | melting part may overlap with the said press injection part. In this way, by providing the melted portion so as to overlap the press-fit portion, the melted portion can be formed at a site where the circumferential clearance (gap) between the sheath tube and the thin portion is not provided. As a result, the melting part provided in the sheath tube can be adjusted to a more appropriate size.
In addition, since the outer surface of the formed melted part is less likely to dent radially inward, the melted part can have a substantially uniform and good shape in the circumferential direction.

  In addition, when setting it as the form which overlaps with a fusion | melting part and a press fit part, it is preferable that a press fit part is provided in a part of thin part. In a portion other than the press-fitting portion (hereinafter referred to as a separation portion), a clearance (gap) is formed between the thin portion and the sheath tube. Then, in this separated portion, heat conduction from the thin portion to the sheath tube can be suppressed during welding. As a result, heat at the time of welding tends to stay in the press-fit portion, and a good molten portion shape can be obtained.

  In the heater according to the present invention, the press-fitting part is provided in a part of the thin-walled part, and the melting part and the press-fitting part are formed so as to be shifted in the axial direction. If the melted part is provided so as to overlap the press-fitted part, internal stress is applied to the melted part, and cracks may occur in the melted part. On the other hand, by providing the press-fitting part and the melting part in a shifted manner, the internal stress of the melting part can be reduced, and cracks in the melting part can be suppressed.

  The heater according to the present invention is characterized in that the melting part is provided on the tip side of the press-fitting part. In this way, by providing the melted portion on the distal end side with respect to the press-fit portion, heat at the time of welding can be suppressed from being conducted through the press-fit portion to the distal end side of the sheath tube having a large volume. Shape can be obtained.

  The heater according to the present invention is characterized in that the melting portion is provided at a tip of the thin portion. In this manner, by forming the melting portion at the tip of the thin portion, the melting portion provided in the sheath tube can be adjusted to a more appropriate size.

An explanatory view in which a heater is arranged in a container. FIG. 2 is a half sectional view showing a heater 10. FIG. 3 is a cross-sectional view showing a detailed configuration of a sheath heater 800. Sectional drawing of the thin part 550 vicinity of the metal shell 500 of 1st Embodiment. 3 is a flowchart showing a method for manufacturing the heater 10. Sectional drawing of the thin part 550a vicinity of the metal shell 500a of 2nd Embodiment. Sectional drawing of the thin part 550b vicinity of the metal shell 500b of 3rd Embodiment.

  FIG. 1 is an explanatory diagram in which the heater 10 is arranged in the container 1. As shown in FIG. 1, a liquid (for example, oil or washer fluid) 2 is placed in a box-like container 1. An attachment portion 3 for attaching the heater 10 is formed on the upper portion of the container 1. The mounting portion 3 is provided with a mounting hole 4 through which the heater 10 is inserted, and an inner screw portion 540 (described later) of the heater 10 is screwed onto the inner surface of the mounting portion 3 facing the mounting hole 4. Is provided. By attaching the heater 10 to the attachment portion 3, the leading end side of the heater 10 protrudes into the container 1 and is exposed to the liquid 2.

  FIG. 2 is a half sectional view showing the heater 10. In addition to the sheath heater 800, the heater 10 mainly includes a middle shaft 200 and a metal shell 500. These members constituting the heater 10 are assembled along the direction of the axis O of the heater 10 (hereinafter also referred to as the axial direction OD). In FIG. 2, an external configuration is illustrated from the axis O to the right side of the drawing, and a cross-sectional configuration is illustrated from the axis O to the left of the drawing. In the present specification, the sheath heater 800 side of the heater 10 is referred to as “front end side”, and the engagement member 100 side is referred to as “rear end side”.

  The metal shell 500 is a member obtained by forming stainless steel such as SUS304 or SUS310S into a cylindrical shape. The metal shell 500 holds the sheath heater 800 at the end on the distal end side. The metal shell 500 holds the central shaft 200 via the insulating member 410 and the O-ring 460 at the end on the rear end side. The insulating member 410 is fixed to the metal shell 500 by crimping the ring 300 in contact with the rear end of the insulating member 410 to the middle shaft 200. Further, the middle shaft 200 extending from the insulating member 410 to the sheath heater 800 is disposed in the shaft hole 510 of the metal shell 500. The shaft hole 510 is a through hole formed along the axis O and has a larger diameter than the middle shaft 200. In a state where the middle shaft 200 is positioned in the shaft hole 510, a gap is formed between the shaft hole 510 and the middle shaft 200 to electrically insulate them. Furthermore, the metal shell 500 includes a main body portion 530 and a thin portion 550 having a thickness smaller than the thickness of the main body portion 530. Among these, the main body portion 530 includes a tool engaging portion 520 and a male screw portion 540. The tool engaging portion 520 of the metal shell 500 engages with a tool (not shown) used for attaching and removing the heater 10. The male screw portion 540 is fitted to the female screw portion 5 formed in the container 1. Further, a thin portion 550 is provided on the front end side of the main body portion 530, and the sheath heater 800 is press-fitted into the thin portion 550 (shaft hole 510) and laser welded to the thin portion 550. The structure of the sheath heater 800 and the thin portion 550 will be described later. The metal shell 500 corresponds to a “housing” in the claims.

  The middle shaft 200 is a member formed of a conductive material into a cylindrical shape (bar shape). The middle shaft 200 is assembled along the axial direction OD while being inserted into the shaft hole 510 of the metal shell 500. The middle shaft 200 includes a front end portion 210 formed on the front end side and a male screw portion 290 provided on the rear end side. The distal end portion 210 is inserted into the sheath heater 800. The male screw portion 290 protrudes from the metal shell 500 to the rear end side. The engaging member 100 is fitted into the male screw portion 290.

  FIG. 3 is a cross-sectional view showing a detailed configuration of the sheath heater 800. The sheath heater 800 is press-fitted into the shaft hole 510 of the metal shell 500 with the distal end portion 210 of the middle shaft 200 inserted into the sheath heater 800. The sheath heater 800 mainly includes a sheath tube 810, a heating coil 820, and an insulator 870.

  The sheath tube 810 is a cylindrical member that extends in the axial direction OD and has a closed tip. The sheath tube 810 includes a heat generating coil 820 and an insulator 870. The sheath tube 810 includes a side surface portion 814 extending in the axial direction OD, a distal end portion 813 that is connected to the distal end side of the side surface portion 814 and is rounded outward, and an end portion that is open on the opposite side of the distal end portion 813. And a rear end portion 819. The distal end portion 210 of the central shaft 200 is inserted from the rear end portion 819 into the sheath tube 810. The sheath tube 810 is electrically insulated from the middle shaft 200 by the packing 600 and the insulator 870. On the other hand, the sheath tube 810 is in contact with and electrically connected to the metal shell 500. The sheath tube 810 is stainless steel such as SUS310S.

  The insulator 870 is formed of a powder of an insulating material having electrical insulating properties. As the insulator 870, for example, magnesium oxide (MgO) powder is used. The insulator 870 fills (arranges) a gap formed in the sheath tube 810 when the sheath tube 810 includes the center shaft 200 and the heating coil 820, and electrically insulates the gap.

  The heating coil 820 is disposed along the axial direction OD inside the sheath tube 810 and generates heat when energized. The heating coil 820 includes a front end portion 822 that is a coil end portion on the front end side, a rear end portion 829 that is a coil end portion on the rear end side, and a spiral portion 823 that connects the front end portion 822 and the rear end portion 829. Prepare. The distal end portion 822 is connected to the distal end portion 813 of the sheath tube 810 and is electrically connected to the sheath tube 810. The rear end portion 829 is electrically connected to the middle shaft 200 by being joined to the front end portion 210 of the middle shaft 200. The heating coil 820 is made of a Fe—Cr—Al alloy, a Ni—Cr alloy, a Co—Ni alloy, Ni, or the like. The heating coil 820 corresponds to a “heating element” in the claims.

  FIG. 4 is a cross-sectional view of the vicinity of the thin portion 550 of the metal shell 500. The cross section of FIG. 4 is a cross section in which the sheath tube 810 and the metal shell 500 are cut at a position passing through the axis O. The middle shaft 200 is shown in a perspective view for simplification. As shown in FIG. 4, the metal shell 500 includes a main body portion 530 and a thin portion 550. The thin part 550 is connected to the distal end side of the main body part 530, and the thickness of the thin part 550 is thinner than the thickness of the main body part 530.

  The sheath tube 810 is inserted through the main body portion 530 and the thin portion 550 (shaft hole 510). At this time, the sheath tube 810 is press-fitted into the thin portion 550, and a press-fit portion 552 is formed in a part of the thin portion 550. Furthermore, the thin-walled portion 550 and the sheath tube 810 are laser welded over the entire circumference, and the melting portion 560 is provided in the circumferential direction. The melting part 560 is provided so as to overlap the press-fitting part 552.

  In the present embodiment, the thickness T1 of the thin portion 550 is made thinner than the thickness T2 of the sheath tube 810. In this embodiment, the thickness of all the thin portions 550 is made thinner than the thickness T2 of the sheath tube 810. The thickness T1 of the thin portion is the thickness T1 of the thin portion 550 at the boundary S1 (rear end side boundary S1) of the outer surface of the thin portion 550 between the non-melting portion 561 and the melting portion 560 adjacent to the melting portion 560. I have identified. This is because the shape of the melted part 560 is changed by welding, and the thickness of the thin part 550 may not be specified in the melted part 560, whereas the boundary S between the non-melted part 561 and the melted part 560 is started. This is because the thickness T1 of the thin portion 550 can be easily specified.

  According to the heater 10 configured as described above, the thickness T1 of the thin portion 550 is made thinner than the thickness T2 of the sheath tube 810. Thereby, the fusion | melting part 560 provided in the sheath pipe | tube 810 can be adjusted to a suitable magnitude | size. As a result, the watertightness of the sheath tube 810 and the main other metal fitting 500 can be ensured, and the sheath tube 810 can be prevented from penetrating and the heating coil 820 being oxidized and consumed. In this embodiment, the thickness T1 of the thin portion 550 at the rear end side boundary S1 is compared with the thickness T2 of the sheath tube 810. However, the thickness of the thin portion 550 at the front end side boundary S2 and the thickness T2 of the sheath tube 810 are compared. May be compared.

  Moreover, the heater 10 of this embodiment is provided with the melting part 560 at a position in the thin part 550 that is separated from the main body 530 in the axial direction OD. When the melted part 560 is formed at the position of the thin part 550 that is separated from the main body part 530 in this way, heat at the time of laser welding becomes difficult to be conducted to the main body part 530, and a good shape of the melted part 560 can be obtained.

  In the heater 10 of the present embodiment, the axial distance between the rear end 562 of the melting portion 560 and the front end 531 of the main body portion 530 is 1.5 mm. Thus, by separating the rear end 562 of the melting part 560 from the front end 531 of the main body part 530 by more than 1 mm, the heat at the time of laser welding becomes more difficult to conduct to the main body part 530 and solidification cracks generated in the melting part 560 Can be prevented from occurring.

  Further, the heater 10 of the present embodiment is provided with a press-fit portion 552 formed by press-fitting the sheath tube 810 on at least a part of the thin portion 550. Thus, by providing the press-fit portion 552 in the thin wall portion 550, the axis of the sheath tube 810 and the thin wall portion 550 can be substantially aligned (can be aligned with the axis O of the heater 10), and the sheath It is possible to suppress the axial displacement of the tube 810 and the thin portion 550. As a result, the melted part 560 formed in the thin wall part 550 can obtain a substantially uniform and good shape in the circumferential direction.

Further, the heater 10 of the present embodiment is provided such that the melting part 560 overlaps the press-fitting part 552. In this way, by providing the melted portion 560 so as to overlap the press-fit portion 552, a portion (that is, the press-fit portion 552) where the circumferential clearance (gap) between the sheath tube 810 and the thin-walled portion 550 is not provided. A melt zone can be formed. As a result, the melting part 560 provided in the sheath tube 810 can be adjusted to a more appropriate size.
In addition, since the outer surface of the formed melted part 560 is less likely to be dented inward in the radial direction, the melted part 560 can have a substantially uniform and good shape in the circumferential direction.

  In the heater 10 of this embodiment, the packing 600 disposed in the sheath tube 810 is disposed so as to overlap the main body 530 and the axial direction OD, and does not overlap the thin portion 550 and the axial direction OD. (See FIG. 3). As a result, the heat generated by the heating coil 820 of the heater 10 can be conducted to the main body 530 without staying in the packing 600, and deterioration of the packing 600 can be suppressed.

  Next, a method for manufacturing the heater 10 will be described. FIG. 5 is a flowchart showing a method for manufacturing the heater 10. In manufacturing the heater 10, first, the heating coil 820 and the center shaft 200 are welded (step S10).

  Next, the distal end portion 822 of the heating coil 820 and the distal end portion 813 of the sheath tube 810 are welded (step S20). When the welding process in step S20 is completed, the insulator 870 is then filled into the sheath tube 810 (step S30). The insulator 870 fills the gap formed in the sheath tube 810 by enclosing the heat generating coil 820 and the middle shaft 200, and the assembly of the sheath heater 800 is completed.

  When the sheath heater 800 is assembled, a swaging process is performed on the sheath heater 800 (step S40). The swaging process is a process of applying a striking force to the sheath heater 800 to reduce the diameter of the sheath heater 800 and densifying the insulator 870 filled in the sheath tube 810. When a striking force is applied to the sheath heater 800 along with the swaging, the striking force is transmitted to the inside of the sheath heater 800, whereby the insulator 870 is densified.

  When the swaging process is performed on the sheath heater 800, the sheath heater 800 is press-fitted into the metal shell 500 (step S50). The sheath heater 800 is inserted from the front end side of the metal shell 500 to form a press-fit portion 552 in the thin portion 550. Thereafter, the metallic shell 500 and the sheath heater 800 are welded (step S60). Laser welding is performed over the entire circumference of the thin wall portion 550 so as to overlap the press-fitting portion 552 of the thin wall portion 550, and a melted portion 560 is formed in the thin wall portion 550 and the sheath tube 810. Thereafter, the heater 10 is assembled (step S70), and the heater 10 is completed. Specifically, at the rear end portion of the metal shell 500, the O-ring 110 and the insulating member 120 are fitted into the middle shaft 200, and the engagement member 140 is attached to the male screw portion 290 of the middle shaft 200 provided at the rear end of the metal shell 500. tighten.

  Next, the heater 10a of 2nd Embodiment is demonstrated. In addition, the heater 10a of 2nd Embodiment differs only in the formation position of the fusion | melting part 560 in the thin part 550 among the heaters 10 of 1st Embodiment, and it is different from the heater 10 of 1st Embodiment about another site | part. It is the same. Therefore, in the following description, it demonstrates centering on the thin part 550a of the heater 10a of 2nd Embodiment, and description of another site | part is simplified or abbreviate | omitted.

  FIG. 6 is a cross-sectional view of the vicinity of the thin portion 550a of the metal shell 500a of the heater 10a. The cross section of FIG. 6 is a cross section obtained by cutting the sheath tube 810 and the metal shell 500a at a position passing through the axis O. The middle shaft 200 is shown in a perspective view for simplification. As shown in FIG. 6, the metal shell 500a includes a main body portion 530a and a thin portion 550a. The thin portion 550a is connected to the distal end side of the main body portion 530a, and the thickness of the thin portion 550a is thinner than the thickness of the main body portion 530a.

  The sheath tube 810 is inserted inside the main body portion 530a and the thin portion 550a (shaft hole 510a). At this time, the sheath tube 810 is press-fitted into the thin portion 550a, and a press-fit portion 552a is formed in a part of the thin portion 550a. And in 2nd Embodiment, the thin part 550a and the sheath pipe | tube 810 are laser-welded over the perimeter, and the fusion | melting part 560a is provided in the circumferential direction. The melting portion 560a is provided so as to be shifted from the press-fit portion 552a in the axial direction OD.

  Also in the heater 10a configured as described above, the thickness T1 of the thin portion 550a is made thinner than the thickness T2 of the sheath tube 810. Thereby, the fusion | melting part 560a provided in the sheath pipe | tube 810 can be adjusted to a suitable magnitude | size. As a result, the watertightness of the sheath tube 810 and the main other metal fitting 500a can be secured, and the sheath tube 810 can be prevented from penetrating and the heating coil 820 being oxidized and consumed. In the present embodiment, the thickness of all the thin portions 550a is made thinner than the thickness T2 of the sheath tube 810.

  Further, the heater 10a of the present embodiment has a press-fit portion 552a provided in a part of the thin portion 550a, and the melted portion 560a and the press-fit portion 552a are formed so as to be shifted in the axial direction OD. Thereby, the internal stress of the fusion | melting part 560a can be reduced and the crack of the fusion | melting part 560a can be suppressed.

  Moreover, the heater 10a of this embodiment has the melting part 560a provided on the tip side of the press-fitting part 552a. In this way, by providing the melting part 560a on the tip side of the press-fitting part 552a, it is possible to suppress heat during welding from being conducted to the tip side of the sheath tube 810 having a large volume via the press-fitting part 552a. A good melted part shape can be obtained.

  Next, the heater 10b of 3rd Embodiment is demonstrated. In addition, the heater 10b of 3rd Embodiment differs only in the formation position of the fusion | melting part 560 in the thin part 550 among the heaters 10 of 1st Embodiment, and it is different from the heater 10 of 1st Embodiment about another site | part. It is the same. Therefore, in the following description, it demonstrates centering on the thin part 550b of the heater 10b of 3rd Embodiment, and description of another site | part is simplified or abbreviate | omitted.

  FIG. 7 is a cross-sectional view of the vicinity of the thin portion 550b of the metal shell 500b of the heater 10b. The cross section of FIG. 7 is a cross section obtained by cutting the sheath tube 810 and the metal shell 500b at a position passing through the axis O. The middle shaft 200 is shown in a perspective view for simplification. As shown in FIG. 7, the metal shell 500b includes a main body portion 530b and a thin portion 550b. The thin portion 550b is connected to the distal end side of the main body portion 530b, and the thickness of the thin portion 550b is smaller than the thickness of the main body portion 530b.

  The sheath tube 810 is inserted inside the main body portion 530b and the thin portion 550b (shaft hole 510b). At this time, the sheath tube 810 is press-fitted into the thin portion 550b, and a press-fit portion 552b is formed in a part of the thin portion 550a. And in 3rd Embodiment, the thin part 550b and the sheath pipe | tube 810 are laser-welded over the perimeter, and the fusion | melting part 560b is provided in the circumferential direction. The melting portion 560a is provided at the tip 551b of the thin portion 550b.

  Also in the heater 10b configured as described above, the thickness T1 of the thin portion 550b is thinner than the thickness T2 of the sheath tube 810. Thereby, the fusion | melting part 560b provided in the sheath pipe | tube 810 can be adjusted to a suitable magnitude | size. As a result, the watertightness of the sheath tube 810 and the main other metal fitting 500b can be secured, and the sheath tube 810 can be prevented from penetrating and the heating coil 820 being oxidized and consumed. In the present embodiment, the thickness of all the thin portions 550b is thinner than the thickness T2 of the sheath tube 810.

  Further, the heater 10b of the present embodiment has a melting portion 560b provided at the tip 551b of the thin portion 550b. In this way, by forming the melting portion 560b at the tip 551b of the thin portion 550b, the melting portion 560b provided in the sheath tube 810 can be adjusted to a more appropriate size.

  Next, the relationship between the distance from the front end 531 of the main body portion 530 of the rear end 562 of the melted portion 560 and solidification cracking was evaluated. At the time of this evaluation, the heater 10 of the first embodiment was created by the above-described manufacturing method. Note that the diameter of the sheath tube 810 before insertion into the metal shell 500 (diameter of the portion disposed in the press-fit portion 552): φ6.2 mm, the diameter of the thin portion 550 in the press-fit portion 552: φ6.94 mm, and the thickness of the thin portion 550 T1: 0.4 mm, sheath tube 810 thickness T2: 0.7 mm, body portion 530 thickness: 1.0 mm, and thin portion 550 in the axial direction OD length: 4 mm. As laser welding conditions, a YAG laser welder was used, the output was 1.5 to 2.5 kW, the rotation speed was 3 s / 1 rotation, and the number of laser shots in one rotation was 65.

  Under these laser welding conditions, a plurality of samples were created by moving the laser irradiation position up and down in the axial direction OD of the thin portion 550. Specifically, ten samples A in which the distance between the rear end 561 of the formed melted part 560 and the front end 531 of the main body part 530 is 1 mm or less, the rear end 561 of the formed melted part 560 and the main body part 530 are formed. 10 samples B whose distance from the tip 531 exceeds 1 mm and becomes 2 mm or less, 10 samples C whose distance between the rear end 561 of the formed melted part 560 and the tip 531 of the main body part 530 exceeds 2 mm, Each was created.

  And about this 30 samples, it was confirmed whether the solidification crack had generate | occur | produced. Whether or not solidification cracking occurred was cut in a direction perpendicular to the axial direction OD at the center position in the axial direction OD of the melted part 560, and the melted part 560 exposed on the cut surface was confirmed by SEM. .

  As a result, in sample A (the distance between the rear end 561 of the formed melted part 560 and the tip 531 of the main body part 530 is 1 mm or less), the number of samples in which solidification cracks occurred in the melted part 560 was three. It was. On the other hand, the sample B (the distance between the rear end 561 of the formed melted part 560 and the front end 531 of the main body part 530 exceeds 1 mm and 2 mm or less) or the sample C (the rear end 561 of the formed melted part 560). And the tip 531 of the main body 530 exceeds 2 mm), the number of samples in which solidification cracks occurred in the melted part 560 was zero. From the above, by separating the rear end 562 of the melting part 560 from the front end 531 of the main body part 530 by more than 1 mm, the heat at the time of laser welding becomes more difficult to conduct to the main body part 530, and solidification generated in the melting part 560 It turns out that it can suppress that a crack generate | occur | produces.

  The present invention is not limited to the embodiments and examples of the present specification, and can be realized with various configurations without departing from the spirit of the present invention.

In the present embodiment, the press-fit portions 552, 552a, and 552b are provided in a part of the thin portions 550, 550a, and 50b. However, the present invention is not limited to this, and may be provided over the entire thin portion. Good.
In the present embodiment, the melted portions 560, 560a, and 560b are provided in a part of the thin-walled portions 550, 550a, and 550b. However, the present invention is not limited to this and is provided over the entire thin-walled portion. May be.
In the present embodiment, the thickness of all the thin portions 550, 550a, and 550b is made thinner than the thickness T2 of the sheath tube 810. However, the thickness is not limited to this, and the thickness T1 of the thin portions 550, 550a, and 550b ( The thickness T1) of the thin portions 550, 550a, and 550b at the positions of the boundaries S1 and S2 only needs to be thinner than the thickness T2 of the sheath tube 810. For example, the thin portions 550, 550a, and 550b are on the distal end side in the axial direction OD. The taper part which becomes thin as it goes to may be sufficient.
In this embodiment, only the heating coil 820 is disposed in the sheath tube 810. However, the present invention is not limited to this, and the heating coil and a control coil for controlling the heating coil are disposed in the sheath tube. It may be.

DESCRIPTION OF SYMBOLS 10, 10a, 10b ... Heater 500, 500a, 500b ... Main metal fitting 550, 550a, 550b ... Thin part 552, 552a, 552b ... Press-fit part 560, 560a, 560b ... Melting part 800 ... Sheath heater 810 ... Sheath tube 820 ... Heating coil

Claims (8)

A cylindrical sheath tube extending in the axial direction and having a closed end portion;
A heating element disposed in the sheath tube and generating heat when energized;
A cylindrical housing for inserting the rear end side of the sheath tube into its cylindrical hole;
With
The housing is disposed on the distal end side of the main body portion and on the distal end side of the main body portion and in the axial direction with respect to the sheath tube, and has a cylindrical thin portion thinner than the thickness of the main body portion, Have
A heater provided with a melted part formed by laser welding over the entire circumference of the thin part and the sheath tube,
The heater according to claim 1, wherein a thickness of the thin portion at a boundary of an outer surface of the thin portion between the non-melting portion adjacent to the melting portion and the melting portion is smaller than a thickness of the sheath tube.   The heater according to claim 1, wherein the melting portion is provided at a position separated from the main body portion in the thin portion.   The heater according to claim 2, wherein an axial distance between a rear end of the melting portion and a front end of the main body is greater than 1 mm.   The heater according to any one of claims 1 to 3, wherein a press-fitting part in which the sheath tube is press-fitted is provided in at least a part of the thin part.   The heater according to claim 4, wherein the melting part is provided so as to overlap the press-fitting part.   The heater according to claim 4, wherein the press-fitting portion is provided in a part of the thin-walled portion, and the melting portion and the press-fitting portion are formed so as to be shifted in the axial direction.   The heater according to claim 6, wherein the melting part is provided on a tip side of the press-fitting part.   The heater according to any one of claims 1 to 7, wherein the melting part is provided at a tip of the thin part.