JP2018128274A - Pressure sensor with heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor with heater capable of hardly causing a weld defect.SOLUTION: Regarding the pressure sensor with heater, an external cylinder part including a press-in part where a heater is pressed in and a non-press-in part connected in the axial direction of the press-in part where the external surface of the heater and its own inner peripheral surface are separated away from each other is held by a main body metal fitting in such a way that it can be displaced with the heater in the axial direction. A welded member includes a first part arranged on the outside of the radial direction of the press-in part and a second part connected to the first part which is to be welded to the non-press-in part. At least that part of the non-press-in part to which the second part is welded, has an external diameter larger than the external diameter of the press-in part in which the heater has been pressed, and also smaller than the internal diameter of the second part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a pressure sensor with a heater, and more particularly to a pressure sensor with a heater that can hardly cause welding defects.

  2. Description of the Related Art As a glow plug used as an auxiliary heat source for an internal combustion engine such as a diesel engine using a compression ignition system, a pressure sensor with a heater to which a function for detecting the pressure of a combustion chamber is added is known. In the pressure sensor with a heater disclosed in Patent Document 1, a heater is press-fitted into a press-fitting portion of an outer cylinder, and the outer cylinder can be displaced together with the heater and is held by the metal shell. On the other hand, a transmission member is disposed on the outer side in the radial direction of the press-fitting part of the outer cylinder and the non-press-fitting part connected to the press-fitting part, and a part of the transmission member is welded to the non-fitting part. This transmission member transmits the displacement of the heater to the sensor unit, and thereby the sensor unit outputs a signal corresponding to the pressure in the combustion chamber (displacement of the heater).

Japanese Patent Laying-Open No. 2015-148386

  However, in the above conventional technique, the outer diameter of the press-fitting portion of the outer cylinder is increased by press-fitting the heater into the outer cylinder. Therefore, it is necessary to set the inner diameter of the transmission member in anticipation of the outer diameter of the outer cylinder after the press-fitting. There is. For this reason, a gap between the non-press-fit portion where the outer diameter of the outer cylinder does not increase and the transmission member becomes large, and defects such as poor penetration and poor fusion may occur with respect to welding between the transmission member and the non-press-fit portion. Therefore, strict management of the welding conditions is necessary to weld the non-press-fit portion and the transmission member (member to be welded) so that defects such as poor penetration and poor fusion do not occur. On the other hand, from the viewpoint of stabilizing the process, it is required to make it difficult to produce welding defects even if the management of welding conditions is relaxed.

  The present invention has been made to meet this demand, and an object of the present invention is to provide a pressure sensor with a heater that can hardly cause a welding defect between a member to be welded and a non-press-fit portion.

  In order to achieve this object, a pressure sensor with a heater according to the present invention is disposed in a shaft hole with a cylindrical metal shell having an axial hole extending in the axial direction and a front end portion protruding from the tip of the metal shell. And a rod-shaped heater having at least an outer surface made of ceramic. Further, the pressure sensor with a heater according to the present invention includes a press-fit portion into which the heater is press-fitted, and a non-press-fit portion that is connected in the axial direction of the press-fit portion and the outer surface of the heater is separated from the inner peripheral surface thereof. And an outer cylinder that is held by the metal shell so as to be axially displaceable together with the heater, a first portion that is disposed on the radially outer side of the press-fit portion, and that is connected to the first portion and welded to the non-press-fit portion A second member to be welded, and a sensor unit that detects displacement in the axial direction of the heater. In the pressure sensor with a heater according to the present invention, the outer diameter of at least the second portion of the non-press-fit portion is larger than the outer diameter of the press-fit portion into which the heater is press-fitted, and is larger than the inner diameter of the second portion. Is also small.

  According to the pressure sensor with a heater according to claim 1, the outer diameter of the portion where at least the second portion of the non-press-fit portion is welded is larger than the outer diameter of the press-fit portion into which the heater is press-fitted. Even if the inner diameter of the welded member is set in anticipation of the outer diameter of the press-fitted portion of the outer cylinder, since the inner diameter is smaller than the inner diameter, the second portion of the non-press-fitted portion and the second portion of the welded member are welded. The gap can be reduced. Therefore, welding defects such as poor penetration and poor fusion can be made difficult to occur in the welded portion between the non-press-fit portion and the second portion of the member to be welded.

  According to the pressure sensor with a heater according to claim 2, the outer diameter of the non-press-fit portion is larger than the outer diameter of the press-fit portion into which the heater is press-fit over the entire length in the axial direction of the non-press-fit portion. Smaller than. Therefore, in addition to the effect of the first aspect, the welded portion between the non-press-fit portion and the second portion can be provided at an arbitrary position of the non-press-fit portion.

  According to the pressure sensor with a heater according to claim 3, since the non-press-fit portion is provided with a plurality of portions where the second part of the welded member is welded, in addition to the effect of claim 1, the non-press-fit portion and The welded portion with the second portion can be provided at a plurality of locations.

  According to the pressure sensor with a heater according to claim 4, the member to be welded is a transmission member that transmits the relative displacement of the heater to the sensor portion. Therefore, in addition to the effect of any one of claims 1 to 3, even in a pressure sensor with a heater using a transmission member, it is possible to hardly cause a welding defect between the transmission member and the non-press-fit portion.

  According to the pressure sensor with a heater according to claim 5, the welded member is a movable member that is deformable along the axial direction with the end opposite to the second part fixed to the metal shell. Therefore, in addition to the effect of any one of claims 1 to 3, even in a pressure sensor with a heater using a movable member, it is possible to hardly cause a welding defect between the movable member and the non-press-fit portion.

It is a fragmentary sectional view of the pressure sensor with a heater in a 1st embodiment of the present invention. It is a fragmentary sectional view in the center part of a pressure sensor with a heater. It is a fragmentary sectional view in the front-end | tip part of a pressure sensor with a heater. It is a fragmentary sectional view in the rear end part of the pressure sensor with a heater. It is a fragmentary sectional view of the pressure sensor with a heater which expanded and showed a part of FIG. It is a fragmentary sectional view in the central part of the pressure sensor with a heater in a 2nd embodiment. It is a fragmentary sectional view in the central part of the pressure sensor with a heater in a 3rd embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. A heater-equipped pressure sensor 10 according to the first embodiment will be described with reference to FIGS. 1 to 4 are partial cross-sectional views of a pressure sensor 10 with a heater according to a first embodiment of the present invention. In FIGS. 1 to 4, the lower side of the paper is referred to as the front end side of the pressure sensor 10 with a heater, and the upper side of the paper is referred to as the rear end side of the pressure sensor 10 with a heater (similarly shown in FIGS. 5 to 7).

  As shown in FIG. 1, the pressure sensor 10 with a heater includes a metal shell 11, a heater 20, a sensor unit 50, and the like. The pressure sensor 10 with a heater is an auxiliary heat source used when starting an internal combustion engine (not shown) such as a diesel engine, and is attached with the tip of the heater 20 exposed to the combustion chamber. It is also used for pressure detection.

  The metal shell 11 is a cylindrical member made of metal (for example, carbon steel or stainless steel) extending in the direction of the axis O. The metal shell 11 has a shaft hole 12 extending along the axis O, and a threaded portion 13 is formed on the outer peripheral surface on the rear end side. A cap member 14 is connected to the rear end of the metal shell 11. The cap member 14 accommodates an output circuit 53 (described later) inside. The cap member 14 has a tool engaging portion 15 formed on the rear end side. The screw portion 13 is a male screw that fits into an internal combustion engine (not shown). The tool engaging portion 15 is a portion having a shape (for example, hexagonal shape) with which a tool (not shown) used when the screw portion 13 is fitted or removed from a screw hole (not shown) of the internal combustion engine. .

  As shown in FIG. 2, the metallic shell 11 has a cylindrical sensor fixing member 16 extending along the axis O direction disposed in the shaft hole 12. The sensor fixing member 16 has a distal end portion 17 joined to the distal end portion of the metal shell 11. The sensor fixing member 16 is a metal member (for example, stainless steel or the like) to which the sensor unit 50 (see FIG. 4) is fixed to the rear end side. A cap member 18 is joined to the distal end portion of the metal shell 11 via the distal end portion 17 of the sensor fixing member 16. The cap member 18 is a substantially frustoconical member for ensuring the airtightness of the combustion chamber in close contact with the seating surface of the internal combustion engine when the pressure sensor 10 with a heater is attached to the internal combustion engine (not shown). Yes, the heater 20 passes through the center.

  As shown in FIG. 3, the heater 20 is inserted inside the sensor fixing member 16 (see FIG. 2) with its own tip protruding from the tip of the metal shell 11. The heater 20 includes a substantially columnar base 21 and a heating element 22 disposed inside the base 21. The base 21 is made of an insulating ceramic such as silicon nitride or alumina. The heating element 22 is formed of conductive ceramics containing silicon nitride as a main component and containing silicide, nitride, carbide, or the like of molybdenum or tungsten. The heating element 22 includes a heating part 23 disposed at the front end of the base body 21 and a pair of lead parts 24 and 25 extending from the heating part 23 toward the rear end side.

  As shown in FIG. 2, the lead portions 24 and 25 are provided with leading portions 26 and 27 on the rear end side, respectively. The lead-out portions 26 and 27 are provided at different positions in the direction of the axis O, protrude toward the outside in the radial direction, and are exposed on the outer peripheral surface of the base 21.

  As shown in FIG. 4, in the metal shell 11, a middle shaft 28 extending along the axis O direction is disposed in the shaft hole 12 with a space in the axis O direction from the rear end of the heater 20. The middle shaft 28 is a rod-shaped member made of metal (for example, stainless steel). The middle shaft 28 is connected to the heater 20 via a connection member 29. The connection member 29 is a cylindrical member made of metal (for example, stainless steel), and the front end portion of the center shaft 28 and the rear end portion of the heater 20 are press-fitted into both end portions of the connection member 29. In the heater 20 press-fitted into the connection member 29, the lead portion 27 comes into contact with the connection member 29, so that the middle shaft 28 is electrically connected to the lead portion 25 through the connection member 29 and the lead portion 27. The rear end side of the middle shaft 28 is electrically connected to a terminal (not shown) of the heater-equipped pressure sensor 10 via a conductive spring (not shown).

  Returning to FIG. The outer cylinder 30 is a cylindrical member made of metal (for example, stainless steel) extending in the direction of the axis O. The outer cylinder 30 includes a press-fit portion 31 into which the heater 20 is press-fitted, and a non-press-fit portion 32 connected to the distal end side of the press-fit portion 31 in the axis O direction. The press-fit portion 31 holds the center of the heater 20 and contacts the drawing portion 26. It is preferable that the inner surface of the press-fit portion 31 is plated with gold. The inner diameter of the non-press-fit portion 32 is larger than the inner diameter of the press-fit portion 31, and the inner peripheral surface of the non-press-fit portion 32 and the outer peripheral surface of the heater 20 are separated from each other. The non-press-fit portion 32 penetrates the cap member 18 with a gap from the inner periphery of the cap member 18. The non-press-fit portion 32 has a movable member 33 joined to the outer peripheral surface.

  The movable member 33 is a member formed in an annular shape with a thin plate made of metal (for example, stainless steel or nickel-base alloy), and a plurality of bent portions having different diameters are continuously provided in the circumferential direction (2 in the present embodiment). Place) is formed. Thereby, the movable member 33 can be elastically deformed in the direction of the axis O. The movable member 33 is disposed in the space between the cap member 18 and the outer cylinder 30, and the inner peripheral portion is joined to the outer peripheral surface of the non-press-fit portion 32 over the entire circumference by laser welding or resistance welding. The outer peripheral part is joined to the outer peripheral surface of the sensor fixing member 16 over the entire periphery. In the present embodiment, welds 34 and 35 formed by laser welding are shown.

  The movable member 33 is electrically connected to the metal shell 11 via the sensor fixing member 16, and is electrically connected to the lead portion 24 via the outer cylinder 30 (non-press-fit portion 32) and the drawer portion 26 of the heater 20. The Thereby, the center shaft 28 and the metal shell 11 are electrically connected to the heat generating portion 23 (see FIG. 3) of the heater 20. Therefore, when the current is passed between the terminal (not shown) to which the middle shaft 28 is connected and the metal shell 11, the heat generating portion 23 of the heater 20 generates heat.

  The inner peripheral part of the movable member 33 is joined to the non-press-fit part 32 via the weld part 34 formed over the entire periphery, and the outer peripheral part of the movable member 33 is formed over the entire periphery. The movable member 33 can be hermetically sealed in the gap between the metal shell 11 or the cap member 18 and the heater 20. Since there is a radial gap between the non-press-fit portion 32 and the cap member 18, the movable member 33 deforms in the direction of the axis O following a change in pressure in the combustion chamber (not shown). With the deformation of the movable member 33, the outer cylinder 30 and the heater 20 are displaced in the axis O direction with respect to the metal shell 11.

  A transmission member 40 (welded member) is disposed between the outer cylinder 30 and the sensor fixing member 16 on the rear end side of the movable member 33 disposed in the shaft hole 12 of the metal shell 11. The transmission member 40 is a cylindrical member made of metal (for example, stainless steel) that extends in the direction of the axis O. The transmission member 40 is connected to the first portion 41 disposed on the radially outer side of the press-fit portion 31 of the outer cylinder 30, and the distal end side of the first portion 41 in the axis O direction, and the radial direction of the non-press-fit portion 32. 2nd part 42 arrange | positioned on the outer side.

  In the transmission member 40, the distal end portion 43 of the second portion 42 is disposed closer to the distal end side than the distal end of the sensor fixing member 16. As for the transmission member 40, the front-end | tip part 43 of the 2nd part 42 is joined to the outer periphery of the non-press-fit part 32 of the outer cylinder 30 by laser welding or resistance welding. As a result, the transmission member 40 moves in the direction of the axis O along with the displacement of the heater 20 and the outer cylinder 30. In the present embodiment, a welded portion 44 formed by laser welding is illustrated. As for the transmission member 40, the 2nd part 42 is joined to the non-press-fit part 32 of the outer cylinder 30 via the welding part 44 formed over the perimeter.

  As shown in FIG. 4, the sensor unit 50 is disposed at the rear ends of the transmission member 40 and the sensor fixing member 16. The sensor unit 50 includes an annular diaphragm 51 made of metal (for example, stainless steel) in which the central shaft 28 passes through the center, and a sensor element 52 (piezoelectric in the present embodiment) joined to a surface on the rear end side of the diaphragm 51. Resistor). When the transmission member 40 is displaced in the direction of the axis O and the diaphragm 51 whose periphery is fixed to the sensor fixing member 16 bends, the resistance value of the sensor element 52 changes. The detection result (resistance value) of the sensor element 52 is processed by an output circuit 53 provided in the cap member 14 (see FIG. 1), and a signal corresponding to the pressure in the combustion chamber is a terminal of the pressure sensor 10 with a heater. (Not shown) is output to an external circuit such as an ECU.

  Next, an example of a manufacturing method of the pressure sensor 10 with a heater will be described. First, the heater 20 to which the connecting member 29 is connected is prepared. Next, the heater 20 is press-fitted into the press-fitting portion 31 of the outer cylinder 30 from the distal end side. Since the press-fit portion 31 is provided with an allowance for the heater 20, when the heater 20 is press-fitted, the outer diameter of the press-fit portion 31 increases. Since the non-press-fit portion 32 of the outer cylinder 30 is separated from the outer peripheral surface of the heater 20, the area of the press-fit portion 31 can be made smaller than when the non-press-fit portion 32 is not provided in the outer cylinder 30. Therefore, the workability of press-fitting the heater 20 into the outer cylinder 30 (press-fit portion 31) can be improved. Thereafter, the central shaft 28 is connected to the connecting member 29 to which the pressure sensor 20 with heater is connected.

  Next, the metal shell 11 to which the sensor fixing member 16 is bonded is prepared. The transmission member 40 is already joined to the sensor fixing member 16 joined to the metal shell 11 via the sensor unit 50. Then, the heater 20 press-fitted into the outer cylinder 30 is inserted from the middle shaft 28 side from the distal end 43 side of the transmission member 40, and the press-fitting part 31 of the outer cylinder 30 is arranged inside the first portion 41 of the transmission member 40. Then, the non-press-fit portion 32 of the outer cylinder 30 is disposed inside the second portion 42 of the transmission member 40. Then, the front-end | tip part 43 of the 2nd part 42 and the non-press-fit part 32 of the outer cylinder 30 are piled up and welded, and the welding part 44 is formed in a perimeter. Since the welded portion 44 is formed in the non-press-fit portion 32, it is possible to make it difficult to transfer the heat of welding to the heater 20 as compared with the case where the welded portion 44 is formed in the press-fit portion 31. Therefore, damage to the heater 20 due to welding heat can be prevented.

  Next, the heater 20 and the outer cylinder 30 (non-press-fit portion 32) are inserted into the movable member 33. The inner peripheral portion of the movable member 33 is disposed on the outer periphery of the non-press-fit portion 32, and the outer peripheral portion of the movable member 33 is disposed on the outer periphery of the sensor fixing member 16. Thereafter, the movable member 33 is welded to the non-press-fit portion 32 and the sensor fixing member 16 to form weld portions 34 and 35 on the entire circumference. Since the welded portion 34 is formed in the non-press-fit portion 32, the heat of welding can be made difficult to be transmitted to the heater 20. Therefore, damage to the heater 20 due to welding heat can be prevented.

  Next, the cap member 18 is put on and joined to the tip of the sensor fixing member 16, and the cap member 18 is fixed to the metal shell 11 via the sensor fixing member 16. After electrical connection of the middle shaft 28 and the like, the cap member 14 is put on to obtain the pressure sensor 10 with a heater.

  FIG. 5 is a partial cross-sectional view of the pressure sensor 10 with a heater showing a part of FIG. 2 in an enlarged manner. As shown in FIG. 5, in the outer cylinder 30, the outer diameter D <b> 1 of the non-press-fit portion 32 is smaller than the inner diameter D <b> 3 of the second portion 42 of the transmission member 40 in the entire length of the non-press-fit portion 32. Thereby, when manufacturing the pressure sensor 10 with a heater, the outer member 30 can be covered with the transmission member 40.

  In the outer cylinder 30, the outer diameter D <b> 1 of the non-press-fit portion 32 is larger than the outer diameter D <b> 2 of the press-fit portion 31 expanded by the press-fitting of the heater 20 in the entire length of the non-press-fit portion 32. Thus, even if the inner diameter D3 of the second portion 42 of the transmission member 40 is set in anticipation that the press-fit portion 31 expands and the outer diameter D2 increases due to the press-fitting of the heater 20, the outer diameter D1 and the inner diameter D3 are set. Since the difference can be reduced, the gap between the non-press-fit portion 32 and the second portion 42 of the transmission member 40 can be reduced. As a result, welding defects such as poor penetration and poor fusion can be made difficult to occur in the welded portion 44.

  Furthermore, since the amount of welding for filling the gap between the non-press-fit portion 32 and the second portion 42 of the transmission member 40 can be reduced, the number of welding steps can be reduced, and the heat input of the second portion 42 and the non-press-fit portion 32 can be reduced. it can. As a result, distortion of the heat affected zone can be suppressed. Even if the management of the welding conditions is relaxed, a welding defect can be made difficult to occur, so that the joining process of the outer cylinder 30 and the transmission member 40 can be stabilized.

  Further, the outer diameter D1 of the non-press-fit portion 32 is larger than the outer diameter D2 of the press-fit portion 31 expanded by the press-fitting of the heater 20 over the entire length of the non-press-fit portion 32 and smaller than the inner diameter D3 of the second portion 42 of the transmission member 40. Therefore, the welded portion 44 can be formed at an arbitrary position, and the positional relationship with the welded portion 34 can be appropriately set. Moreover, since the thickness of the non-press-fit part 32 can be ensured over the entire length of the non-press-fit part 32, the strength of the non-press-fit part 32 can be ensured.

  Next, a second embodiment will be described with reference to FIG. In the first embodiment, the case where the outer diameter D1 of the non-press-fit portion 32 is larger than the outer diameter D2 of the press-fit portion 31 after press-fitting the heater 20 over the entire length of the non-press-fit portion 32 has been described. On the other hand, in 2nd Embodiment, when the outer diameter of the site | part 73 where the 2nd part 42 of the transmission member 40 is welded among the non-press-fit parts 72 is larger than the outer diameter of the press-fit part 71 after the heater 20 press-fit. Will be described. In addition, about the part same as the part demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. FIG. 6 is a partial cross-sectional view of the central portion of the pressure sensor 60 with a heater according to the second embodiment.

  As shown in FIG. 6, in the pressure sensor 60 with a heater, an outer cylinder 70 is fixed to the base body 21 (the heater 20, see FIG. 3). The outer cylinder 70 is a cylindrical member made of metal (for example, stainless steel) extending in the direction of the axis O. The outer cylinder 70 includes a press-fit portion 71 into which the heater 20 is press-fitted and a non-press-fit portion 72 connected in the direction of the axis O of the press-fit portion 71. The press-fit portion 71 has a tightening margin with respect to the heater 20, and the non-press-fit portion 72 has its inner peripheral surface separated from the outer peripheral surface of the heater 20 (base 21).

  In the outer cylinder 70, the outer diameter of the portions 73 and 74 where the welded portions 34 and 44 are formed in the non-press-fit portion 72 is larger than the outer diameter of the press-fit portion 71 after the heater 20 press-fit, and the inner diameter of the second portion 42. Smaller than. The outer diameter of the non-press-fit portion 72 other than the portions 73 and 74 is smaller than the outer diameter of the portions 73 and 74 and is the same diameter as the press-fit portion 71. The portions 73 and 74 are formed in an annular shape over the entire circumference of the non-press-fit portion 72. The part 73 is arrange | positioned rather than the part 74 at the rear end side (FIG. 6 upper side), and the 2nd part 42 of the transmission member 40 is welded. The movable member 33 is welded to a portion 74 disposed on the distal end side (lower side in FIG. 6) with respect to the portion 73.

  According to the present embodiment, the portion 73 of the non-press-fit portion 72 is larger than the outer diameter of the press-fit portion 71 after the press-fitting of the heater 20 and smaller than the inner diameter of the second portion 42. Therefore, as in the first embodiment. The gap between the portion 73 and the second portion 42 can be reduced. As a result, welding defects such as poor penetration and poor fusion can be made difficult to occur in the welded portion 44.

  In addition, since the portion 74 to be welded to the movable member 33 is formed in the non-press-fit portion 72, the inner diameter of the movable member 33 can be increased compared to the case where the portion 74 having a large outer diameter is not formed in the non-press-fit portion 72. Can be bigger. As a result, since the dimension of the movable member 33 in the radial direction can be reduced, the movable member 33 can be formed with less material than when there is no portion 74.

  Next, a third embodiment will be described with reference to FIG. In 1st Embodiment and 2nd Embodiment, the case where the transmission member 40 and the movable member 33 were welded to the outer cylinders 30 and 70 was demonstrated. On the other hand, in the third embodiment, the outer cylinder 81 is divided into a first outer cylinder 82 and a second outer cylinder 84, the transmission member 40 is welded to the first outer cylinder 82, and the movable member 90 is attached to the second outer cylinder 84. The case of welding is described. In addition, about the part same as the part demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. FIG. 7 is a partial cross-sectional view of the center portion of the pressure sensor 80 with a heater according to the third embodiment.

  As shown in FIG. 7, in the pressure sensor 80 with a heater, an outer cylinder 81 is fixed to the base 21 (heater 20, see FIG. 3). The outer cylinder 81 includes a first outer cylinder 82 to which the transmission member 40 (member to be welded) is welded and a second outer cylinder 84 to which the movable member 90 (member to be welded) is welded.

  The first outer cylinder 82 is a cylindrical member made of metal (for example, stainless steel or the like) extending in the direction of the axis O. The first outer cylinder 82 includes a press-fit portion 31 into which the heater 20 is press-fitted and a non-press-fit portion 83 connected in the direction of the axis O of the press-fit portion 31. The press-fit portion 31 is set with a tightening margin with respect to the heater 20, and the non-press-fit portion 83 has its inner peripheral surface separated from the outer peripheral surface of the heater 20 (base 21). The outer diameter of the non-press-fit portion 83 is larger than the outer diameter of the press-fit portion 31 after the heater 20 is press-fitted, and is smaller than the inner diameter of the transmission member 40 (second portion 42). A welding portion 44 for welding the transmission member 40 and the non-press-fit portion 83 is formed in the non-press-fit portion 83.

  The second outer cylinder 84 is a cylindrical member made of metal (for example, stainless steel) extending in the direction of the axis O. The second outer cylinder 84 includes a press-fit portion 85 into which the heater 20 is press-fitted, and a non-press-fit portion 86 connected in the direction of the axis O of the press-fit portion 85. The press-fit portion 85 has a tightening margin with respect to the heater 20, and the non-press-fit portion 86 has its inner peripheral surface separated from the outer peripheral surface of the heater 20 (base 21). The second outer cylinder 84 is disposed on the distal end side in the axis O direction from the first outer cylinder 82. The outer diameter of the non-pressing part 86 is larger than the outer diameter of the press-fitting part 85 after the heater 20 is press-fitted, and is smaller than the inner diameter of the second part 92 (described later) of the movable member 90. A welding portion 94 for welding the movable member 90 and the non-press-fit portion 86 to the non-press-fit portion 86 is formed.

  The movable member 90 is a member formed in an annular shape with a thin plate made of metal (for example, stainless steel or nickel-based alloy). In the present embodiment, the movable member 90 is formed by joining the inner movable member 91 and the outer movable member 95. It has been. The inner movable member 91 includes a first portion 92 disposed outside the press-fit portion 85 in the radial direction, and a second portion 93 connected to the first portion 92 and disposed outside the non-press-fit portion 86 in the radial direction. (Inner periphery). The outer movable member 95 is disposed on the outer peripheral side of the inner movable member 91. The inner peripheral end 96 of the outer movable member 95 is joined to the first portion 92 of the inner movable member 91 by laser welding or resistance welding. In the present embodiment, a weld 99 formed by laser welding is illustrated.

  By laser welding or resistance welding, the inner movable member 91 has the second portion 93 joined to the outer peripheral surface of the non-press-fit portion 86 over the entire circumference, and the outer movable member 95 has the outer end 97 on the outer circumference side. It is joined to the outer peripheral surface of the sensor fixing member 16. In the present embodiment, welded portions 94 and 98 formed by laser welding are illustrated. The movable member 90 is disposed in a space between the cap member 100 and the sensor fixing member 16.

  Next, an example of a manufacturing method of the pressure sensor 80 with a heater will be described. First, the heater 20 (see FIG. 3) to which the connecting member 29 (see FIG. 2) is connected is prepared. Then, after the heater 20 is press-fitted into the press-fit portion 31 of the first outer cylinder 82 from the front end side, the heater 20 is press-fitted into the press-fit portion 85 of the second outer cylinder 84 from the front end side. The press-fit portions 31 and 85 into which the heater 20 is press-fitted expands outward in the radial direction. Thereafter, the central shaft 28 is connected to the connection member 29 to which the heater 20 is connected.

  Next, the metal shell 11 to which the sensor fixing member 16 is bonded is prepared. The transmission member 40 is already joined to the sensor fixing member 16 joined to the metal shell 11 via the sensor unit 50. From the front end side of the transmission member 40, the heater 20 to which the first outer cylinder 82 and the second outer cylinder 84 are fixed is inserted from the middle shaft 28 side. The press-fit portion 31 of the first outer cylinder 82 is disposed inside the first portion 41 of the transmission member 40, and the non-press-fit portion 83 of the first outer cylinder 82 is disposed inside the second portion 42 of the transmission member 40. The second portion 42 and the non-press-fit portion 83 of the first outer cylinder 82 are overlapped and welded to form the welded portion 44 on the entire circumference.

  Next, the inner movable member 91 is disposed outside the second outer cylinder 84 in the radial direction. The first portion 92 of the inner movable member 91 is disposed on the outer periphery of the press-fit portion 85, and the second portion 93 of the inner movable member 91 is disposed on the outer periphery of the non-press-fit portion 86. Since the outer diameter of the non-press-fit portion 86 is larger than the outer diameter of the press-fit portion 85 after the heater 20 is press-fitted and smaller than the inner diameter of the second portion 93 of the inner movable member 91, the second portion 93 of the inner movable member 91 is press-fitted. The portion 85 can be passed and disposed on the outer periphery of the non-press-fit portion 86. Thereafter, the second portion 93 of the inner movable member 91 and the non-press-fit portion 86 are laser-welded to form a welded portion 94 on the entire circumference of the second portion 93. Since the welded portion 94 is formed in the non-press-fit portion 86, the heat of welding can be made difficult to be transmitted to the heater 20, and damage to the heater 20 due to the heat of welding can be prevented.

  Next, the outer movable member 95 is disposed outside the inner movable member 91 in the radial direction. Then, the end portion 96 of the outer movable member 95 and the first portion 92 of the inner movable member 91 are laser welded to form a welded portion 99 on the entire circumference of the first portion 92. Thereafter, the end 97 on the outer peripheral side of the outer movable member 95 is disposed on the outer periphery of the sensor fixing member 16, the end 97 of the outer movable member 95 and the sensor fixing member 16 are welded, and a welded portion 98 is formed over the entire periphery. Form. Thereby, the movable member 90 is fixed to the metal shell 11 via the sensor fixing member 16.

  Next, the cap member 100 is put on and joined to the tip of the sensor fixing member 16, and the cap member 100 is fixed to the metal shell 11 via the sensor fixing member 16. After electrical connection of the middle shaft 28 (see FIG. 4) and the like, the cap member 14 (see FIG. 1) is put on to obtain a pressure sensor 80 with a heater.

  According to the present embodiment, the outer diameter of the non-press-fit portion 83 of the first outer cylinder 82 is larger than the outer diameter of the press-fit portion 31 after the heater 20 press-fit, and smaller than the inner diameter of the second portion 42 of the transmission member 40. Therefore, as in the first embodiment, the gap between the non-press-fit portion 83 and the second portion 42 can be reduced. As a result, welding defects such as poor penetration and poor fusion can be made difficult to occur in the welded portion 44.

  In addition, since the outer diameter of the non-pressing portion 86 of the second outer cylinder 84 is larger than the outer diameter of the pressing portion 85 after the heater 20 is press-fitted and smaller than the inner diameter of the second portion 93 of the movable member 90, the non-pressing portion 86. And the second portion 93 can be reduced. As a result, welding defects such as poor penetration and poor fusion can be hardly generated in the welded portion 94 formed in the second portion 93.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  In each of the above-described embodiments, the welded portion 44 between the second portion 42 of the transmission member 40 and the non-pressed portions 32 and 83 and the portion 73 of the non-pressed portion 72, or the welded portion 94 between the movable member 90 and the non-pressed portion 86. However, the present invention is not necessarily limited to this. Of course, it is possible to provide a plurality of welds in the direction of the axis O in consideration of the bonding strength and the restriction of the formation range of the welds.

  In each of the above-described embodiments, the case where the welded portion 44 that joins the second portion 42 of the transmission member 40 and the non-press-fit portions 32 and 83 is formed over the entire circumference of the second portion 42 has been described. It is not necessarily limited to this. If the mechanical strength of the welded portion 44 can be ensured, it is naturally possible to use spot welding intermittently provided in the circumferential direction of the second portion 42.

  In each of the above embodiments, the case where the lead-out portion 27 of the heater 20 and the middle shaft 28 are mechanically and electrically connected by the connecting member 29 that connects the heater 20 and the middle shaft 28 has been described. It is not limited. In addition to the member that mechanically connects the heater 20 and the middle shaft 28, it is naturally possible to electrically connect the lead-out portion 27 and the middle shaft 28 using a lead wire or the like.

  In each of the above embodiments, the case where a piezoresistor is used as the sensor element 52 has been described. However, the present invention is not necessarily limited thereto. Of course, another element such as a piezoelectric element capable of detecting displacement can be used instead of the piezoresistor.

  In each of the embodiments described above, the heater 20 has been described with respect to the case where the base 21 is formed in a substantially cylindrical shape, but is not necessarily limited thereto. The heater 20 is not particularly limited as long as it has a rod shape, and the cross section orthogonal to the axis O may be an elliptical shape, a polygonal shape, or the like. Of course, it is possible to employ a so-called plate heater in which a plurality of plate-like substrates are arranged and a heating element is sandwiched between the substrates.

  Although the case where the heater 20 is press-fitted into the press-fit portion 31 of the outer cylinder 80 (first outer cylinder 81) has been described in the third embodiment, the present invention is not necessarily limited thereto. Of course, it is possible to fix the first outer cylinder 81 and the heater 20 by brazing or the like, omitting the press-fitting portion 31 of the first outer cylinder 81.

10, 60, 80 Pressure sensor with heater 11 Metal shell 12 Shaft hole 20 Heater 30, 70, 81 Outer cylinder 31, 71, 85 Press-fit portion 32, 72, 83, 86 Non-press-fit portion 40 Transmission member (member to be welded)
41 1st part 42 2nd part 50 Sensor part 73,74 Parts 90 Movable member (member to be welded)
92 1st part 93 2nd part 97 End O-axis

Claims (5)

A cylindrical metal shell having an axial hole extending in the axial direction;
A rod-shaped heater which is disposed in the shaft hole in a state in which its tip end protrudes from the tip of the metal shell, and at least the outer surface is made of ceramic,
A press-fit portion into which the heater is press-fitted, and a non-press-fit portion that is connected in the axial direction of the press-fit portion and that separates the outer surface of the heater and the inner peripheral surface of the heater. An outer cylinder held by the metal shell so as to be displaceable in a direction;
A member to be welded having a first portion disposed on the radially outer side of the press-fit portion, and a second portion connected to the first portion and welded to the non-press-fit portion;
A pressure sensor with a heater comprising: a sensor unit that detects displacement in the axial direction of the heater;
A pressure sensor with a heater in which the outer diameter of at least the second portion of the non-press-fit portion is larger than the outer diameter of the press-fit portion into which the heater is press-fitted and smaller than the inner diameter of the second portion. .   2. The outer diameter of the non-press-fit portion is larger than the outer diameter of the press-fit portion into which the heater is press-fitted and smaller than the inner diameter of the second portion in the entire axial length of the non-press-fit portion. Pressure sensor with heater.   The pressure sensor with a heater according to claim 1, wherein the non-press-fit portion is provided with a plurality of the portions.   The pressure sensor with a heater according to any one of claims 1 to 3, wherein the member to be welded is a transmission member that transmits a relative displacement of the heater to the sensor unit.   4. The heater according to claim 1, wherein the welded member is a movable member that has an end opposite to the second part fixed to the metal shell and is deformable along the axial direction. 5. With pressure sensor.

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