JP6514055B2 - Method of manufacturing gas sensor element and mask - Google Patents

Description

  The present invention relates to a method of manufacturing a gas sensor element in which an electrode is formed on the outer surface of a bottomed cylindrical solid electrolyte body, and a mask that can be used for the method of manufacturing this gas sensor element.

  Conventionally, an oxygen sensor incorporating an oxygen detection element is used to detect the oxygen concentration in the exhaust gas discharged from an internal combustion engine such as a car and control the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine There is. The oxygen detection element is a solid electrolyte body (hereinafter referred to as a base) in which one end in the axial direction is closed and the other end is opened, and a collar portion projecting outward in the radial direction is formed substantially in the middle in the axial direction. And a reference electrode and a detection electrode made of platinum on the inner surface and the outer surface of the substrate.

  The detection electrode has a detection portion, a lead portion, and a terminal connection portion, and the detection portion is generally formed on the entire outer surface from the tip end (closed end) to the buttock or its vicinity There is. Further, the lead portion has a thin line shape extending in the axial direction from the detection portion to the vicinity of the rear end portion of the base. Furthermore, the terminal connection portion is formed so as to be connected to the rear end portion of the lead portion so as to be connected in a circumferential direction of the base. On the other hand, the reference electrode is formed on the entire inner surface of the base.

Such an oxygen detection element is generally formed as follows.
First, a base material (for example, ZrO ₂ ) is press-formed to form a molded body. Next, a noble metal paste containing platinum, palladium or the like is printed on the outer surface of the molded body on the portion where the lead portion and the terminal connection portion are formed, and then the noble metal paste is baked simultaneously with the baking of the molded body. Thus, a base (hereinafter, referred to as an element intermediate) on which the lead portion and the terminal connection portion are formed is obtained.

  Next, a nucleus is attached to a portion of the outer surface of the element intermediate on which a detection portion is to be formed (nucleating step), and a noble metal is deposited on the attached nucleus using electroless plating. (Plating step) Further, an aging process is performed. Thereafter, the entire inner surface of the element intermediate on which the detection portion is formed is subjected to a nucleation step and a plating step in the same manner as described above, and is further subjected to an aging treatment to form oxygen having a detection electrode and a reference electrode formed on the substrate. A detection element is obtained.

By the way, in recent years, various techniques have been proposed for the purpose of reducing the amount of use of the expensive noble metal used for the electrode.
For example, in Patent Document 1 below, the area of the detection portion at the tip of the oxygen detection element is made smaller than in the prior art, and for example, the detection portion has a shape formed only in about half of the circumferential direction of the oxygen detection element There is disclosed a technique of providing a strip-like lead portion (first lead portion) on the tip end side and connecting the first lead portion and a lead portion (second lead portion) on the rear end side.

JP 2014-2130 A

  By the way, in order to simultaneously form the detection portion and the first lead portion formed only in about a half of the circumferential direction of the oxygen detection element as in this patent document 1, an element intermediate body in which a nucleus is attached It is conceivable that plating is performed by covering the surface with a mask corresponding to the detection unit and the first lead unit.

  As this mask, for example, as shown in FIG. 10, a substantially cylindrical mask P3 in which an opening P2 is formed so as to cover a part of the tip end side of the element intermediate P1 is used. Specifically, the opening P2 of the mask P3 is a first opening P5 corresponding to the shape of the detection portion P4 (ie, the first opening P5 whose tip side is open at a predetermined angle when viewed from the axial direction), A second opening P7 (that is, a second opening P7 which is narrower in width than the first opening P5 and extends in the axial direction) corresponding to the shape of the one lead portion P6 is formed.

However, since the plating solution is supplied along the opening P2 of the mask P3 when plating is performed, a difference in plating film thickness may occur between the detection portion P4 and the first lead portion P6.
That is, since there is a large difference in the inflow area of the plating solution between the first opening P5 and the second opening P7 (that is, the inflow area of the first opening P5 is about several times larger than the inflow area of the second opening P7. Because it is large, the difference in the flow rate of the plating solution also becomes large. Specifically, since the flow velocity of the plating solution in the first opening P5 is smaller (slower) than the flow velocity of the plating solution in the second opening P7, the film thickness of the detection portion P4 formed in the first opening P5 is It becomes smaller than the film thickness of the 1st lead part P6 formed in the 2nd opening P7.

  Therefore, if plating is performed under the condition to secure the film thickness necessary for the film thickness of the detection part P4, the film thickness of the first lead part P6 becomes larger than necessary, and many precious metals constituting the electrode are necessary. There was a problem of becoming

  As a countermeasure, if plating is performed under the condition that the film thickness of the first lead portion P6 does not become excessive, on the contrary, the film thickness of the detection portion P4 can not be sufficiently secured, and the durability is lowered. there were.

  The present invention has been made to solve the above-described problems, and can reduce the electrode material and ensure sufficient durability. A method of manufacturing a gas sensor element and a mask that can be used for the method of manufacturing The purpose is to provide.

  (1) A method of manufacturing a gas sensor element according to the first aspect of the present invention comprises an electrode on the outer surface of a cylindrical solid electrolyte body having a bottom on one side in the axial direction and an opening on the other side; The electrode is disposed on the bottom side, and at least a part thereof is a gas sensor element having a detection part formed in only a part in the circumferential direction and a lead part extending from the detection part to the opening side and narrower than the detection part It relates to the method.

  In this method of manufacturing a gas sensor element, a solid electrolyte body is inserted into a cylindrical mask having a slit, and a slit is overlapped on an electrode formation portion on the outer surface of the solid electrolyte body to form an electrode, and the electrode formation portion is removed. A first step of covering the non-electrode-formed portion with a mask, and a second step of supplying a plating solution to the electrode-formed portion not covered by the mask and depositing metal in the plating solution to form an electrode; Have.

  The slit of the mask used at the time of plating mentioned above communicates with the first opening which the detection section can be formed by the flow of the plating solution, and the lead opening by the flow of the plating solution. And the second opening which can be formed.

  Furthermore, when viewed from the axial direction, the maximum of the opening angle formed by both side faces forming the first opening is smaller than the minimum of the crossing angle formed by the two straight lines connecting the axis and both ends of the detection unit . That is, the maximum of the opening angle of both side surfaces is set to a narrower range than the minimum of the crossing angle.

  Therefore, in the first step, the mask of the above-described configuration is covered on the solid electrolyte body, and in the second step, the plating solution is applied to the first opening and the second opening of the mask which is the exposed portion of the solid electrolyte body. When forming an electrode having a detection portion and a lead portion on a solid electrolyte body by circulating the same, the film thickness of metal (formed by plating) in the detection portion and the lead portion is made more uniform than in the prior art be able to.

  In other words, both side surfaces forming the first opening corresponding to the detection portion do not have a wide spread of the opening angle as in the prior art, and the angle is restricted and narrowed. The difference in flow velocity of the plating solution flowing through the opening and the second opening is reduced. Therefore, the film thickness of the metal in a detection part and a lead part can be equalized conventionally.

  Therefore, even if plating is performed to secure the film thickness necessary for durability as the detection unit, it is possible to suppress the film thickness of the lead portion from becoming larger than necessary. As a result, the electrode material can be reduced, and the gas sensor element having sufficient durability can be manufactured.

  Note that “the maximum opening angle formed by both side surfaces forming the first opening” means the most angle in the case where both side surfaces of the first opening extend in the axial direction and intersect as seen in the axial direction. Refers to the opening angle at which Further, “minimum of crossing angle” refers to a crossing angle at which the angle becomes the smallest when both ends of the detection unit extend in the axial direction and also cross as viewed in the axial direction.

(2) In the method of manufacturing a gas sensor element according to the second aspect of the present invention, the opening angle of both side surfaces is smaller than the minimum of the crossing angle in the entire side surfaces as viewed from the axial direction.
The second aspect exemplifies a preferable form of both sides forming the first opening. Thereby, in plating, the difference in the flow velocity of the plating solution flowing through the first opening and the second opening becomes smaller. Therefore, the film thickness of the metal in a detection part and a lead part can be equalized more.

  (3) In the method of manufacturing a gas sensor element according to the third aspect of the present invention, the mask is provided with two connection surfaces that respectively connect the two side surfaces and the solid electrolyte body when the solid electrolyte body is inserted into the mask, The opening angle of the two connection surfaces is larger than the opening angle of both side surfaces.

  When viewed from the axial direction, when the both side surfaces forming the first opening are directly connected to the solid electrolyte body (that is, when the flow path of the plating solution is suddenly narrowed), the plating solution When supplying H.sub.2, a large force is applied in the direction (circumferential direction) in which the first opening spreads. As a result, the sealability of the contact portion between the side surfaces forming the first opening and the solid electrolyte body may be reduced, which may cause bleeding due to plating.

  On the other hand, in the third embodiment, two connecting surfaces which are larger than the opening angle of the two side surfaces are provided between the two side surfaces and the solid electrolyte body. As a result, the force applied in the circumferential direction of the first opening is smaller than in the case where both side surfaces are in direct contact with the solid electrolyte body, a sufficient sealing force can be secured, and plating bleeding can be suppressed.

  As a result, since variations in plating thickness can be reduced, the durability of the electrode (particularly the detection portion) can be improved, and the width of the electrode (particularly the detection portion) can be made to have a target dimension. As a result, high sensor characteristics can be realized.

  (4) The mask according to the fourth aspect of the present invention is an electrode formed on the outer surface of a cylindrical solid electrolyte body having a bottom on one side in the axial direction and an opening on the other side, the bottom side An electrode, which is disposed at least a part of which is at least partially formed in only a part in the circumferential direction and has a lead portion extending from the detection portion to the opening side and narrower than the detection portion, is formed using a plating solution At the same time, a solid electrolyte body is inserted, and a slit formed in itself is overlapped on an electrode forming portion forming an electrode on the outer surface of the solid electrolyte body, and a non-electrode forming portion excluding the electrode forming portion is covered. It relates to a cylindrical mask.

  The slit of the mask communicates with the first opening in which the detection portion is formed by the flow of the plating solution, and the first opening, and the second opening in which the lead portion is formed by the flow of the plating solution. Have a department.

  Furthermore, when viewed from the axial direction, the maximum of the opening angle formed by both side surfaces forming the first opening is set smaller than the minimum of the crossing angle formed by two straight lines connecting the axis and both ends of the detection unit .

By performing plating using this mask, the same effect as that of the first aspect can be obtained.
(5) In the mask of the fifth aspect of the present invention, the opening angle of both side surfaces is set to be smaller than the minimum of the crossing angle in the entire side surfaces as viewed from the axial direction.

By performing plating using this mask, the same effect as that of the second embodiment can be obtained.
(6) The mask according to the sixth aspect of the present invention further comprises two connection surfaces respectively connecting the two side surfaces and the solid electrolyte body when the solid electrolyte body is inserted into the mask, and viewed from the axial direction, 2 The opening angle of the two connection surfaces is greater than the opening angle of the two side surfaces.

  By performing plating using this mask, the same effect as that of the third aspect can be obtained.

The gas sensor element manufactured by the manufacturing method of the gas sensor element of 1st Embodiment is shown, (a) is the top view seen from the axial direction front end side of a gas sensor element, (b) is a front view of a gas sensor element, (c) is. The side view of a gas sensor element. The mask used by the manufacturing method of the gas sensor element of 1st Embodiment is shown, (a) is the top view seen from the axial direction tip side of a mask, (b) is a front view of a mask, (c) is a side view of a mask . (A) is a top view which expands and shows a mask, (b) is a figure which expands and shows A part in (a). The front view which shows the element intermediate in the middle of manufacture of a gas sensor element. The assembled body which put the mask on the element intermediate body is shown, (a) is the top view seen from the axial direction tip end side of the assembled body, (b) is a front view of the assembled body, (c) is an assembled body Side view. Sectional drawing which shows the state which fixed the assembly body to the fixing hole of a mask fixed board. The state which has plated the surface of the element intermediate body of an assembly body is shown, (a) is the top view seen from the axial direction front end side of the assembly body after plating, (b) is a front view of the assembly body after plating (C) is a side view of the assembly after plating. Sectional drawing which fractured | ruptured the oxygen sensor with which the gas sensor element was assembled | attached along the axial direction. (A) is a top view which expands and shows the mask of 2nd Embodiment, (b) is a figure which expands and shows B part in (a). The assembled body after plating of a prior art is shown, (a) is the top view seen from the axial direction front end side of an assembled body, (b) is a front view of an assembled body, (c) is the side of an assembled body Figure.

Hereinafter, an embodiment of a method of manufacturing a gas sensor element of the present invention and a mask used in the method of manufacturing the same will be described.
[1. First embodiment]
[1-1. Gas sensor element]
First, the configuration of the gas sensor element manufactured by the method for manufacturing a gas sensor element of the first embodiment will be described.

  As shown in FIG. 1, the gas sensor element 1 is used as a detection element of the oxygen sensor 71 (see FIG. 8), and includes a base 5 made of a solid electrolyte body mainly composed of zirconia.

  The base 5 is a substantially cylindrical member extending in the direction of the axis O (axial direction: the vertical direction in FIG. 1B), and the bottom 7 is closed in one of the axial directions (above the FIG. 1B). And an opening 9 opened at the other side (lower side of FIG. 1 (b)).

An annular flange 11 is provided on the outer peripheral surface of the base 5 at a substantially central portion in the axial direction, and protrudes radially outward from the base 5 over the entire circumference of the base 5 in the circumferential direction.
Hereinafter, the bottom 7 side of the base 5 will be referred to as the tip end side, and the opening 9 side will be referred to as the rear end side. Further, in the base body 5, the tip end side of the collar portion 11 is referred to as a tip end portion 13, and the rear end side of the collar portion 11 is referred to as a rear end portion 15.

  In addition, an outer electrode (detection electrode) 17 made of, for example, Pt is formed on the outer peripheral surface of the base 5 (hatched part in FIG. 1), and an inner electrode (reference electrode) made of, for example, Pt on the inner peripheral surface. 19 is formed.

  The detection electrode 17 is connected to a detection portion 21 formed on the tip end side of the tip end portion 13, a lead portion 23 extending from the detection portion 21 to the rear end side along the axial direction, and the lead portion 23 It consists of the terminal connection part 25 formed in the circumferential direction.

  Among these, as shown in FIG. 1A, the detection unit 21 has a predetermined angle (crossing angle α1) in the circumferential direction around the axis O as viewed from the axial direction, that is, a fan shape Is formed.

  Specifically, when viewed from the side on which the lead portion 23 is formed (downward in FIG. 1A), the detection unit 21 connects the axis O to the end of the detection unit on the left side. The crossing angle α1 between the right side 21R connecting the end of the detection unit and the right side is set, for example, in the range of 90 ° to 180 °.

  The lead portion 23 is formed to be narrower than the detection portion 21 as shown in FIG. 1B, and is a first lead portion extending from the detection portion 21 to the central portion 27 of the collar portion 11 along the axial direction. A second lead portion 31 is narrower than the first lead portion 29 and extends from the central portion 27 of the collar portion 11 to the rear end side. The first lead portion 29 and the second lead portion 31 overlap at the central portion 27 of the collar portion 11 and are electrically connected.

The terminal connection portion 25 is an annular electrode connected to the rear end side of the second lead portion 31 and formed perpendicularly to the second lead portion 31.
[1-2. Method of manufacturing gas sensor element]
Next, a method of manufacturing the gas sensor element 1 of the first embodiment will be described.

<Structure of mask>
First, the structure of the mask 41 used in the plating step described later will be described.
As shown in FIG. 2, the mask 41 used in the first embodiment is a part of the rear end 15 (the tip adjacent to the ridge 11) from the tip 13 of the base 5 through the ridge 11 It is a cylindrical plating mask that covers the entire area, and is made of a rubber member having stretchable elasticity.

  Specifically, the mask 41 has a hollow portion 43 which extends in the axial direction and has a shape corresponding to the outer shape of the base 5, and a slit 48 communicating with the hollow portion 43. The slit 48 communicates with the first opening 45 forming the detection unit 21 by the flow of the plating solution, and the first opening 45, and the width in the circumferential direction is narrower than the first opening 45, and the plating solution It has the 2nd opening 47 which forms the 1st lead part 29 by circulating.

  As shown in FIG. 2A, the first opening 45 is fan-shaped at the same crossing angle α1 as the detection unit 21 with the axis O at the center. The rear end side (the lower part in FIG. 2B) of the first opening 45 is a plane perpendicular to the axial direction, and the left and right wall parts in FIG. 2B sandwiching the second opening 47 Left and right tip surfaces 46La, 46Ra of 46L, 46R are exposed to the first opening 45.

  The mask 41 also has a pair of bottom surfaces 49 forming the first opening 45. Specifically, as shown in FIG. 2B, a pair of bottom surfaces 49 (left bottom surface 49L) are formed on the tip end side in the axial direction at the intersection angle α1 about the axis O (see FIG. 2A). , Right bottom surface 49R).

Furthermore, on the slit 48 of the mask 41, both side surfaces 57 (left side surface 57L, right side surface 57R) forming the first opening 45 are formed.
The slit 48 of the mask 41 has a pair of connection surfaces 55 (left connection surface 55L, right connection surface 55R) forming the first opening 45 so as to connect the both side surfaces 57 and the bottom surface 49. It is formed.

  That is, the right side connection surface 55R and the right side surface 57R are connected to the right end 51R of the right bottom surface 49R. Similarly, the left connection surface 55L and the left surface 57L are connected to the left end 51L of the left bottom surface 49L.

  Then, as shown in an enlarged manner in FIG. 3A, when viewed from the axial direction, the angle (opening angle α2) formed by the both side surfaces 57 is set smaller than the intersection angle α1 (for example, more than 0 ° Less than 90 °).

The opening angle α2 of the side surfaces 57 is set to be smaller than the minimum of the intersection angle α1 in the entire side surface 57 as viewed in the axial direction.
On the other hand, the angle (opening angle α3) formed by the pair of connection surfaces 55 is less than or equal to the intersection angle α1 of the detection unit 21 (in the first embodiment, smaller than the intersection angle α1). It is set large (for example, more than 0 ° and less than 180 °).

  3B (the hatched portion corresponds to the slit 48), the pair of connection surfaces 55 (for example, the left connection surface 55L) has a pair of bottom surfaces 49 (for example, the left bottom surface 49L). , And both side surfaces 57 (eg, left side surface 57L) are inclined at a fifth angle α5 with respect to the pair of connection surfaces 55 (eg, left connection surface 55L).

<Production procedure of gas sensor element>
Next, a manufacturing procedure of the gas sensor element 1 performed using the mask 41 will be described.

  First, in order to produce the base 5 provided with the ridge portion 11, a ceramic material (for example, a material of a solid electrolyte body mainly composed of zirconia) is put in a mold as in the conventional case, and predetermined by a known press molding method. A molded body is produced.

Next, as is well known, a pattern to be the second lead portion 31 and the terminal connection portion 25 is formed on the surface of the molded body by printing using platinum paste.
Thereafter, this is baked, for example, at 1500 ° C. for about 2 hours to manufacture the base 5 (that is, the element intermediate 61) having the second lead portion 31 and the terminal connection portion 25 as shown in FIG.

  Alternatively, after the ceramic material is put in a mold and the base material of the base 5 is manufactured, the surface of the base material is cut to form the base 5 provided with the ridge portion 11, and the second lead portion 31 and the terminal connection portion After forming a pattern to be 25, the element intermediate 61 can be manufactured by firing.

Next, on the outer surface of the element intermediate body 61, a known nucleation as a pretreatment for plating is performed on the tip end portion 13 and the tip end side of the center portion 27 of the ridge portion 11 (dot portion in FIG. 4). .
For example, the nucleated part of the element intermediate 61 is immersed in a platinum complex salt aqueous solution (for example, a tetravalent platinum ammine aqueous solution or a divalent platinum ammine aqueous solution) (platinum concentration: 45 g / m ³ ). Further, the platinum complex aqueous solution in which the element intermediate 61 is immersed is heated to 60 ° C., and an aqueous solution of sodium borohydride is added. Then, the element intermediate 61 is left for 10 minutes while being shaken in the nucleation solution which is the mixed solution, and platinum nuclei are deposited on the outer surface of the half element 61.

  Next, as shown in FIG. 5, the mask 41 is placed from the tip side of the element intermediate 61. Specifically, after the rear end opening 43a on the rear end side of the hollow portion 43 of the mask 41 is aligned with the front end of the element intermediate 61, the mask 41 is pushed downward from above in FIG. 5 (b).

When the second lead portion 31 is pressed, the center of the second opening 47 of the mask 41 in the circumferential direction is made to coincide with the position of the second lead portion 31.
The hollow portion 43 of the mask 41 is formed to match the outer shape of the element intermediate 61, and therefore, when the mask 41 is placed on the element intermediate 61, the mask 41 adheres to the surface of the element intermediate 61. .

  Further, as shown in FIG. 5 (b), the mask 48 is formed with the slit 48 consisting of the first opening 45 and the second opening 47 described above. 61 is exposed. Specifically, the second lead portion 31 is visible at the center of the second opening 47.

Since the mask 41 only covers only the front end side of the rear end portion 15 of the element intermediate 61, the half element 61 is exposed at the rear end side.
Next, as shown in FIG. 6, the mask 41 is pressed together with the element intermediate 61 into the fixing holes 65 of the mask fixing plate 63 and fixed.

In this state (that is, in the state of an assembled body in which the mask 41 is placed on the element intermediate 61), plating is performed on the nucleated surface of the element intermediate 61 by a known method.
For example, in the plating step, the mask fixing plate 63 on which the element intermediate 61 and the mask 41 are integrally fixed is formed of a platinum complex salt aqueous solution (for example, tetravalent platinum ammine solution or divalent platinum ammine solution) (platinum concentration: 600 g / m ³ Soak in) and heat. Then, to the platinum complex salt aqueous solution in which this element intermediate 61 is immersed, add a hydrazine aqueous solution (concentration: 85 mass%) having a reducing power to such an extent that platinum does not precipitate other than the part where the nucleus is attached. The element intermediate 61 is left to swing for about 2 hours in a plating solution, and platinum is deposited on the nuclei adhering to the outer surface of the element intermediate 61.

  In this plating step, as shown in FIG. 7, in the outer surface of the element intermediate 61, the portion where the mask 41 is not attached (electrode forming portion 42), that is, the first opening 45 corresponding to the detecting portion 21. Among the exposed portion and the exposed portion of the second opening 47 corresponding to the first lead portion 29, platinum is deposited at the nucleused portion (hatched hatched portion at the left). .

  When the plating process is completed in this manner, the element intermediate 61 to which the mask 41 is attached is removed from the mask fixing plate 63, and the mask 41 is removed from the element intermediate 61. Thereafter, the outer surface of the element intermediate 61 is washed with water and dried.

Then, a well-known aging process is performed on a portion of the outer surface of the element intermediate 61 on which platinum nuclei are grown, to complete the gas sensor element 1.
In addition, in order to protect the surface of the detection part 21 of the gas sensor element 1, spinel powder is thermally sprayed by the plasma spraying method, and an electrode protective layer (not shown) is formed.

Further, although the reference electrode 19 is formed on the inner surface of the gas sensor element 1 by the same plating process, the method is the same as the conventional method, so the description thereof is omitted.
[1-3. Oxygen sensor]
Next, the oxygen sensor 71 which is a gas sensor provided with the gas sensor element 1 mentioned above is demonstrated. Note that “upper” and “lower” below indicate “upper” and “lower” in FIG.

  As shown in FIG. 8, the oxygen sensor 71 extends in the axial direction (vertical direction in FIG. 8) and has the bottomed cylindrical gas sensor element 1 closed at the tip end (downward in FIG. 8) and the inside of the gas sensor element 1. A rod-shaped ceramic heater 75 arranged to heat the gas sensor element 1 and a casing 77 for accommodating the internal structure of the oxygen sensor 71 and fixing the oxygen sensor 71 to a mounting portion such as an exhaust pipe are provided.

  Among these, the casing 77 holds the gas sensor element 1 and causes the detection portion 21 of the tip end portion 13 of the end portion 13 to project inside the exhaust pipe etc., and the rear end side of the metal shell 81 (the upper side of FIG. And a metal outer cylinder 83 that forms a reference gas space with the gas sensor element 1.

  The metal shell 81 includes a cylindrical holder 85 made of ceramic for supporting the gas sensor element 1 from below, a cylindrical filling member 87 made of talc powder filled on the upper portion of the holder 85, and the filling member 87. The cylindrical sleeve 89 etc. which consist of a ceramic pressed from are accommodated in an inside.

  That is, on the inner periphery of the lower end side of the metal shell 81, an inward projecting step portion 91 is provided, and the holder 85 is locked to the step portion 91 via a metal packing 93. The flange portion 11 of the gas sensor element 1 is supported from below.

  A filling member 87 is disposed between the inner peripheral surface of the metal shell 81 on the upper side of the holder 85 and the outer peripheral surface of the gas sensor element 1, and further, a sleeve 89 and a packing 95 made of metal on the upper side of the filling member 87. The upper end portion of the metal shell 81 is crimped inward (downward) in a state in which the upper end portion is sequentially coaxially inserted, and the filling member 87 is pressurized and filled. Thus, the gas sensor element 1 is firmly fixed to the metal shell 81.

  In addition, a metal dual protector 97 having a plurality of holes is attached to the outer periphery of the lower end side of the metal shell 81 while covering the projecting portion (tip 13) of the gas sensor element 1 by welding.

  On the other hand, after the lower opening end of the outer cylinder 83 is extrapolated to the metal shell 81 so as to cover the upper opening of the metal shell 81, welding is applied to the lower opening end from the outside, and the outer cylinder Reference numeral 83 is attached to the metal shell 81.

In the vicinity of the upper opening of the outer cylinder 83, a cylindrical separator 99 made of ceramic having electrical insulation is inserted.
The separator 99 has a flange portion 101 protruding radially outward on an outer peripheral surface near the axial center. The separator 99 is held inside the outer cylinder 83 via a metal cylindrical holding member 103 locked to the flange portion 101.

  Further, the separator 99 has a plurality of insertion holes 109 penetrating from the rear end surface 105 to the tip surface 107 and a recess 113 formed in the tip surface 107 so as to be able to accommodate the rear end 111 of the ceramic heater 75. Have.

  Then, the separator 99 accommodates the rear end sides of the outer electrode terminal 115 and the inner electrode terminal 117 in different insertion holes 109 to insulate the outer electrode terminal 115 and the inner electrode terminal 117 from each other. , The insulation between the outer electrode terminal 115 and the outer cylinder 83, and the insulation between the inner electrode terminal 117 and the outer cylinder 83.

  The outer electrode terminal 115 is disposed to electrically connect the detection electrode 17 disposed on the outer peripheral surface of the gas sensor element 1 and the lead wire 121 (in contact with the terminal connection portion 25 of the gas sensor element 1). The inner electrode terminal 117 is disposed to electrically connect the reference electrode 19 disposed on the inner peripheral surface of the gas sensor element 1 and the lead wire 125.

  Further, the upper opening of the outer cylinder 83 is closed by a grommets 129 made of fluorine resin, and the lead wires 125 and 127 connected to the lead wires 121 and 123 and the ceramic heater 75 penetrate the grommet 129. It is arranged.

  The lead wires 121, 123, 125, and 127 are electrically connected to a sensor control device (not shown) provided at a distance from the oxygen sensor 71 or an electronic control unit (ECU) of a vehicle.

[1-4. effect]
In the first embodiment, the slit 48 of the mask 41 used for plating communicates with the first opening 45 that can be formed by the detection unit 21 by the flow of the plating solution, and to the first opening 45. And a second opening 47 in which the first lead portion 29 can be formed by the flow of the plating solution.

  Furthermore, when viewed from the axial direction, an opening angle α2 formed by both side surfaces 57 forming the first opening 45 is a straight line connecting the axis O and each end 51 (left end 51L, right end 51R) of the detection unit 21. It is set smaller than the crossing angle α1 formed by 21L and 21R (see FIG. 2A).

  Therefore, the mask 41 having the above-described configuration is covered on the base 5 (specifically, the element intermediate 61), and the plating solution is applied from the first opening 45 and the second opening 47 of the mask 41 which is the exposed portion of the element intermediate 61. The film thickness of the metal (formed by plating) in the detection unit 21 and the first lead unit 29 by supplying and forming an electrode having the detection unit 21 and the first lead unit 29 on the element intermediate body 61 Can be made more uniform than before.

  That is, both side surfaces 57 forming the first opening 45 corresponding to the detection unit 21 are not widely spread as in the prior art, and the angle is restricted and narrowed. The difference in flow velocity of the plating solution flowing through the opening 45 and the second opening 47 is reduced. Therefore, the film thickness of the metal in the detection part 21 and the 1st lead part 29 can be equalized conventionally.

  Therefore, even if plating is performed as the detection unit 21 in order to secure the film thickness necessary for durability, the film thickness of the first lead portion 29 will not be larger than necessary. As a result, the electrode material can be reduced, and the gas sensor element 1 capable of securing sufficient durability can be produced.

  Moreover, in the first embodiment, when the mask 41 is inserted into the solid electrolyte body (the base 5 and the element intermediate 61) in the mask 41, two connections for connecting the both side surfaces 57 and the solid electrolyte body are provided. Since two connection surfaces 55 which are the surfaces 55 and in which the opening angle α3 is larger than the opening angle α2 are provided, the sealing force can be secured and the plating bleeding can be suppressed.

  As a result, since variations in plating thickness can be reduced, the durability of the electrode (particularly the detection portion 21) can be improved, and the width of the electrode (particularly the detection portion 21) can be made to a target size, realizing high sensor characteristics. can do.

[2. Other embodiments]
Next, another embodiment will be described. The same components as those in the first embodiment will be described using the same reference numerals.

As shown in FIG. 9A, in the second embodiment, the shape of the mask 131 used in the plating step similar to that of the first embodiment is different.
As in the first embodiment, the mask 131 used in the second embodiment has a pair of bottom surfaces 49 (left bottom surface 49L, right side) formed at the intersection angle α1 with the axis O at the center on the tip side in the axial direction. Bottom surface 49R).

Further, both side surfaces 133 (left side surface 133L, right side surface 133R) are connected so as to extend in the radial direction from a pair of end portions 51 (left end portion 51L, right end portion 51R) of the pair of bottom surfaces 49.
In the second embodiment, a pair of connection surfaces similar to those of the first embodiment is not formed, and the entire side surface 133 is bent from the pair of first ends 51, as shown in FIG. Extends vertically.

  More specifically, as shown in FIG. 9B, the side surfaces 133 (for example, the left side surface 133L) have the fourth angle α4 and the fifth angle α4 with respect to the pair of bottom surfaces 49 (for example, left bottom surface 49L). And the sixth angle α6 is inclined.

Also in the second embodiment, the film thickness of the detection unit 21 and the first lead unit 29 can be made uniform.
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken.

  For example, in the gas sensor element 1 of the first embodiment and the second embodiment, the entire detection unit 21 (from the front end to the rear end) has a predetermined angle circumferentially about the axis O when viewed from the axial direction Although it is formed on the base 5 so as to become, without being limited thereto, the tip end side of the detection portion is provided on the entire circumference in the circumferential direction on the tip end side of the base, and the detection portion provided on the entire circumference The rear end side of the detection unit may be provided on the base so as to have a predetermined angle in the circumferential direction so as to be connected to the front end side. Also in this case, the present invention can be achieved by disposing the mask of the first embodiment or the second embodiment only on the rear end side of the detection unit.

1 ... gas sensor element 5 ... substrate (solid electrolyte body)
17 ... detection electrode (outside electrode)
21 detection portion 23 lead portion 29 first lead portion 31 second lead portion 41, 131 mask 42 electrode formation portion 45 first opening portion 47 second opening portion 55 connection surface 57, 133 side

Claims (6)

An electrode is provided on the outer surface of a cylindrical solid electrolyte body having a bottom on one side in the axial direction and an opening on the other side, the electrode being disposed on the bottom side, at least a part of which is circumferentially A method of manufacturing a gas sensor element, comprising: a detection part formed only in a part of the part; and a lead part extending from the detection part to the opening and narrower than the detection part,
The solid electrolyte body is inserted into a cylindrical mask having a slit, and the slit is overlapped on an electrode formation portion forming the electrode on the outer surface of the solid electrolyte body, and the non-electrode excluding the electrode formation portion A first step of covering the formation location with a mask;
A second step of supplying a plating solution to the electrode formation portion not covered by the mask and depositing a metal in the plating solution to form the electrode;
A method of manufacturing a gas sensor element having
The slit of the mask is
The plating solution is communicated with the first opening in which the detection unit is formed by circulating the plating solution, and the second opening in which the lead is formed by circulating the plating solution. And
When viewed from the axial direction, the maximum of the opening angle formed by both side faces forming the first opening is smaller than the minimum of the crossing angle formed by the two straight lines connecting the axis and both ends of the detection unit. The manufacturing method of the gas sensor element characterized by the above.   The method for manufacturing a gas sensor element according to claim 1, wherein an opening angle of the both side surfaces is smaller than a minimum of the crossing angle in the entire side surfaces as viewed from the axial direction. The mask includes two connection surfaces respectively connecting the both side surfaces and the solid electrolyte body when the solid electrolyte body is inserted into the mask,
The method for manufacturing a gas sensor element according to claim 1 or 2, wherein an opening angle of the two connection surfaces is larger than an opening angle of the both side surfaces when viewed from the axial direction. An electrode formed on the outer surface of a cylindrical solid electrolyte body having a bottom on one side in the axial direction and an opening on the other side, the electrode being disposed on the bottom side, at least a part of which is one of the circumferential directions. When forming an electrode having a detection part formed only in the part and a lead part extending from the detection part to the opening side and having a narrower width than the detection part using a plating solution, the solid electrolyte body is formed. While inserting the slit formed in the electrode formation location which forms the said electrode among the outer surface of the said solid electrolyte body, it is a cylindrical mask which covers the non-electrode formation location except the said electrode formation location. There,
The slit communicates with the first opening, which can be formed by the detection section by the flow of the plating solution, and the first opening, and the lead can be formed by the flow of the plating solution. And a second opening,
When viewed from the axial direction, said maximum sides open angle to form a first opening is smaller than the minimum intersection angle of the two straight lines connecting the both ends of the detection portion and the axis forms A mask characterized by   5. The mask according to claim 4, wherein an opening angle of the both side surfaces is smaller than a minimum of the crossing angle in the entire side surface as viewed from the axial direction. When the solid electrolyte body is inserted into the mask, the method further comprises two connection faces respectively connecting the two side faces and the solid electrolyte body,
The mask according to claim 4 or 5, wherein an opening angle of the two connection surfaces is larger than an opening angle of the both side surfaces when viewed from the axial direction.