JP2012242133A - Gas sensor and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor capable of easily assembling a heater to a heater holder, having excellent vibration resistance, and preventing the heater from coming off from the heater holder, and to provide a manufacturing method of the same.SOLUTION: A gas sensor 1 including a sensor element 2; a heater 4 inserted in the sensor element 2; and a metallic heater holder 6 for holding the heater 4 and fixing the heater 4 to the sensor element 2, and a manufacturing method of the gas sensor 1 are provided. The heater holder has: a backbone portion extending in an axial direction; a pair of gripping portions 613 and a pair of element fixing portions 614 formed to extend to the heater side in a generally vertical direction to the axial direction; and a pressing portion 635 for pressing the heater 4 in a diametrical direction of the gas sensor. The gripping portions 613 and the element fixing portions 614 have opening portions 619 opening in the same direction on side surface opposing to the backbone portion 610. The element fixing portion 614 are formed with projecting portions 618 projecting out from the opening portions 619 to the backbone portion 610 side.

Description

  The present invention relates to a gas sensor for detecting a specific gas concentration in a gas to be measured and a method for manufacturing the same.

  Conventionally, an exhaust system such as an internal combustion engine of an automobile is provided with a gas sensor for measuring the concentration of a specific gas such as oxygen or nitrogen oxide in the exhaust gas. As shown in FIG. 10, the gas sensor 9 is formed in a bottomed cylindrical shape, the reference electrode 912 in contact with the reference gas is formed on the inner surface, and the measurement electrode 914 in contact with the gas to be measured is formed on the outer surface. A sensor element 91 that detects the concentration of a specific gas in the gas to be measured, a housing 92 that supports and fixes the sensor element 91 in the gas flow path to be measured, and a sensor element 91. A rod-shaped heater 93 inserted and disposed in the insulator, an insulator 94 made of an insulating material for inserting and holding the base end portion 930 of the heater 93, and holding the heater 93, fixing the heater 93 to the sensor element 91, A metal heater holder 95 electrically connected to the reference electrode 912 of the sensor element 91, and a reference electrically connected to the reference electrode 912 via the heater holder 95 A signal line 98, at least comprises sensors and a measurement side signal line 99 electrically conductive to the measuring electrode 914 is known (see Patent Documents 1 and 2).

As the heater holder 95, various shapes have been developed. Specifically, as the heater holder 95, a grip portion 953 that grips the heater 93 and fixes the heater 93 to the heater holder 95, and the heater holder 95 that is inserted into the sensor element 91 and fixed to the sensor element 91. Some have at least an element fixing portion 952 (see FIG. 11). As the heater holder 95, a heater holder 951 is used in which a pressing portion 951 that presses the heater 93 in the radial direction of the gas sensor 9 from the side surface is formed (see Patent Documents 1 and 2 and FIG. 11). By the pressing portion 951, the tip end portion 931 of the heater 93 abuts on the inner surface of the sensor element 95, and the tip end portion 931 of the heater 93 can be fixed to the sensor element 95.
Moreover, as the heater holder 95, the thing of the substantially cylindrical shape by which one side surface opened as a whole is known (refer patent document 1 and 2). Thus, by providing the opening on the side surface, the assembly of the heater 93 to the heater holder 95 is facilitated.

Japanese Patent Laid-Open No. 10-54822 JP 2001-56312 A

  However, when the heater 93 is pressed from the side surface by the pressing portion 951 of the heater holder 95, the heater 93 may be detached from the opening 959 of the heater holder 95 (see FIGS. 11 and 12). That is, in order to assemble the heater 93 to the heater holder 95 from the side during assembly, it is necessary to form the opening 959 on the side facing the pressing portion 951. Therefore, when the heater 93 is pressed from the side surface in the direction 901 of the opening 959 by the pressing portion 951, stress is generated in which the tip of the heater 93 presses the inner surface of the sensor element 91, and the heater holder grip portion 953 A stress is generated in the direction 902 in which the heater 93 is detached from the opening 959 with respect to the opening 93. For this reason, the heater 93 may be detached from the heater holder 95. In particular, the heater 93 is easily detached from the heater holder 95 during vibration.

  The present invention has been made in view of such problems, and is intended to provide a gas sensor that is easy to assemble a heater to a heater holder, has excellent vibration resistance, and can prevent the heater from being detached from the heater holder, and a method for manufacturing the same. It is what.

The first invention comprises an ion-conducting solid electrolyte body formed in a bottomed cylindrical shape, having a reference electrode in contact with the reference gas formed on the inner surface and a measurement electrode formed in contact with the gas to be measured on the outer surface. A sensor element for detecting the concentration of a specific gas in the gas to be measured;
A heater inserted and arranged in the sensor element;
At least a metal heater holder that grips the heater and fixes the heater to the sensor element and is electrically connected to the reference electrode of the sensor element,
The heater holder includes a backbone portion extending in the axial direction, a pair of gripping portions formed to extend toward the heater in a direction substantially perpendicular to the axial direction, and the heater in the direction substantially perpendicular to the axial direction. A pair of element fixing portions formed so as to extend to the side, contacting the inner surface of the solid electrolyte body in the sensor element, fixing the heater holder to the sensor element, and electrically conducting to the reference electrode; A distal end extending portion that extends from the spine to the distal end side in the axial direction; and a pressing portion that is formed on the distal end extending portion and presses the heater in the radial direction of the gas sensor.
The grip part and the element fixing part have an opening part whose side face facing the spine part opens in the same direction,
In the gas sensor, the element fixing portion is formed with a protrusion that protrudes from the opening toward the spine.

According to a second aspect of the present invention, in the gas sensor manufacturing method according to the first aspect of the present invention, an assembly step is performed in which the heater is assembled to the heater holder by inserting the heater from the side surface through the opening of the heater holder. When,
The assembly is inserted and arranged in the solid electrolyte body of the sensor element, and the tip of the heater pressed in the radial direction of the gas sensor by the pressing portion of the heater holder is brought into contact with the inner side surface of the solid electrolyte body. And a step of inserting the gas sensor.

  In the gas sensor, as described above, the gripping portion and the element fixing portion of the heater holder have an opening portion whose side surface facing the spine portion opens in the same direction. That is, the side surface of the heater holder opens in the same direction. Therefore, in the gas sensor, when the heater is assembled to the heater holder, the heater can be assembled from the side of the heater holder through the opening. Therefore, the heater can be easily assembled to the heater holder.

  Further, the element fixing portion of the heater holder is formed with a protrusion that protrudes from the opening toward the spine. Therefore, even if the pressing portion presses the side surface of the heater in the radial direction of the gas sensor, the protrusion becomes a fulcrum of stress due to the pressing portion, and the heater is detached from the opening of the heater holder. Can be prevented. Therefore, it is possible to prevent the heater from being detached from the heater holder even during vibration.

  As described above, according to the first aspect of the present invention, it is possible to provide a gas sensor that is easy to assemble the heater to the heater holder, has excellent vibration resistance, and can prevent the heater from being detached from the heater holder.

Next, in the manufacturing method, the gas sensor is manufactured by performing the assembly process and the insertion process.
In the assembly step, the heater is inserted from the side through the opening of the heater holder. Thereby, the side surface of the heater can be gripped by the grip portion of the heater holder, and the heater can be assembled to the heater holder to produce an assembly.

In the insertion step, the assembly is inserted and disposed in the solid electrolyte body of the sensor element. And the front-end | tip part of the said heater pressed by the radial direction of the said gas sensor by the said press part of the said heater holder is made to contact | abut to the said inner surface of the said solid electrolyte body.
In this way, the gas sensor can be manufactured.
The operational effects of the second invention are the same as those of the first invention.

1 is a longitudinal sectional view of a gas sensor in Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is an explanatory view showing a cross section in the radial direction of a heater holder that holds a heater in Embodiment 1, and is a cross-sectional view taken along line AA in FIG. 2, a cross-sectional view taken along line BB in FIG. CC sectional view (c) in FIG. 2, DD sectional view (d) in FIG. 2, EE sectional view (e) in FIG. FIG. 3 is a perspective view of a heater holder in the first embodiment. The front view which looked at the heater holder in Example 1 from the opening part side. FIG. 3 is an explanatory diagram illustrating a state where the heater assembled to the heater holder is inserted into the sensor element in the first embodiment. FIG. 2A is a diagram of a heater holder that grips the heater in the first embodiment when viewed from the axial direction of the sensor, and is an explanatory view showing a state in which the heater holder is not inserted into the sensor element. Explanatory drawing (b) which shows the state pressed from. It is explanatory drawing which shows the process of assembling a heater in a heater holder in Example 1, Comprising: (a) which shows a mode that a heater is inserted in a heater holder from the side, Explanatory drawing (b) which shows the state assembled | attached to the heater holder . The front view which looked at the heater holder in Example 2 from the opening part side. Vertical section of a conventional gas sensor In the conventional gas sensor, explanatory drawing which shows a mode that a heater is pressed to radial direction by the press part of a heater holder. In the conventional gas sensor, the explanatory view which looked at a mode that a heater detached from a heater holder from an axial direction.

Next, a preferred embodiment of the present invention will be described. In the present specification, the gas sensor will be described with the side exposed to the gas to be measured as the distal end side and the opposite side as the proximal end side.
Examples of the gas sensor include an air-fuel ratio sensor that is installed in an exhaust pipe of an internal combustion engine for various vehicles such as an automobile engine and used for an exhaust gas feedback system, and an oxygen sensor that measures an oxygen concentration in exhaust gas.

The gas sensor is formed in a cylindrical shape with a bottom, and includes an ion conductive solid electrolyte body in which a reference electrode in contact with a reference gas is formed on an inner surface and a measurement electrode in contact with a gas to be measured is formed on an outer surface. A sensor element for detecting the concentration of the specific gas in the measurement gas is included. Examples of the bottomed cylindrical shape include a bottomed cylindrical shape.
The gas sensor includes a heater that is inserted and arranged in the sensor element, specifically, the bottomed cylindrical solid electrolyte body.
The heater can be constituted by, for example, a rod-shaped (columnar) ceramic heater. The heater generates heat by electrical conduction, and a pair of lead wires for conducting electricity can be formed on the side surface of the heater.

The gas sensor includes a metal heater holder that holds the heater, fixes the heater to the sensor element, and is electrically connected to the reference electrode of the sensor element.
The heater holder includes a backbone portion extending in the axial direction, a pair of gripping portions formed to extend toward the heater in a direction substantially perpendicular to the axial direction, and the heater in the direction substantially perpendicular to the axial direction. A pair of element fixing portions formed so as to extend to the side, contacting the inner surface of the solid electrolyte body in the sensor element, fixing the heater holder to the sensor element, and electrically conducting to the reference electrode; A distal end extending portion extending from the spine portion toward the distal end in the axial direction, and the heater formed on the distal end extending portion is pressed in the radial direction of the gas sensor (from the spine portion side to the opening portion side). And a pressing portion.

  In the heater holder, the heater can be fixed to the heater holder by the gripping part gripping the side surface of the heater. Further, the heater holder can be fixed to the sensor element by inserting the element fixing portion into the bottomed cylindrical solid electrolyte body of the sensor element. At this time, for example, the element fixing portion of the heater holder can be electrically connected to the reference electrode formed on the inner surface of the solid electrolyte body. Moreover, the said heater can be pressed from the side by the said press part, and at least the front-end | tip part of the said heater can be contact | abutted to the inner surface of the said sensor element.

In the heater holder, the element fixing portion is formed with a protrusion protruding from the opening toward the spine portion.
The protrusion may be in contact with the side surface of the heater, but may not be in contact.
When the protrusion is in contact with the side surface of the heater, the stress by which the pressing portion presses the side surface of the heater can be reduced by the stress by which the protrusion presses the side surface of the heater.
In addition, when the protrusion is not in contact with the side surface of the heater, for example, when the heater is likely to be detached from the opening of the heater holder during vibration, the protrusion is in contact with the side surface of the heater. Can be eliminated.

It is preferable that the protrusion in the element fixing portion is formed by folding an end of the element fixing portion on the opening side toward the heater.
In this case, the protrusion can be easily formed. Further, the protrusion can be easily formed after the heater is assembled to the heater holder. Therefore, it can be avoided that the assembling property of the heater to the heater holder is impaired by the protrusion.

Preferably, the tip of the heater and the inner surface of the solid electrolyte body, and the protrusion of the side surface of the heater and the element fixing portion are in contact with each other.
The heater can be fixed to the solid electrolyte body by bringing the tip of the heater into contact with the inner surface of the solid electrolyte body. Therefore, vibration resistance can be improved.
Further, by bringing the side surface of the heater into contact with the protruding portion of the element fixing portion, as described above, the pressing portion presses the side surface of the heater, and the protruding portion presses the side surface of the heater. It can be reduced by stress.

Next, in the gas sensor manufacturing method, the assembly process and the insertion process are performed.
In the assembling step, the heater is assembled into the heater holder by inserting the heater from the side of the opening of the heater holder to produce an assembly.
Further, in the inserting step, the assembly is inserted and arranged in the solid electrolyte body of the sensor element, and the tip of the heater pressed in the radial direction of the gas sensor by the pressing portion of the heater holder is placed in the solid state. It is made to contact | abut to the said inner surface of an electrolyte body. At this time, the side surface of the heater can be brought into contact with the protrusion in the element fixing portion of the heater holder, but a gap can be provided between the protrusion and the side surface of the heater without contact.

In the insertion step, the assembly is inserted and arranged in the solid electrolyte body of the sensor element, whereby the element fixing portion of the heater holder is pressed by the inner surface of the solid electrolyte body, and a pair of elements is formed. It is preferable to reduce the interval between the fixing portions.
In this case, in the assembling step, the distance between the pair of element fixing portions can be increased, so that it is possible to avoid difficulty in assembling the heater to the heater holder.

Example 1
Next, the gas sensor 1 according to the embodiment will be described with reference to FIGS.
As shown in FIG. 1, the gas sensor 1 of this example includes at least a sensor element 2, a heater 4, and a heater holder 6.

  The sensor element 2 is formed in a cylindrical shape with a bottom, an ion conductive solid electrolyte in which a reference electrode 215 in contact with the reference gas is formed on the inner surface 21 and a measurement electrode 225 in contact with the gas to be measured is formed on the outer surface 22. It consists of a body 20. The heater 4 is inserted into the solid electrolyte body 20 of the sensor element 2 and heats the sensor element 2. The heater holder 6 holds the heater 4, fixes the heater 4 to the sensor element 2, and is electrically connected to the reference electrode 215 of the sensor element 2.

As shown in FIGS. 1 to 4, the heater holder 6 includes a backbone portion 610 extending in the axial direction, and a pair of gripping portions 613 that are formed to extend toward the heater 4 in a direction substantially perpendicular to the axial direction. The sensor element 2 is formed so as to extend toward the heater 4 in a direction substantially perpendicular to the axial direction, contacts the inner surface 21 of the solid electrolyte body 20 in the sensor element 2, fixes the heater holder 6 to the sensor element 2, and electrically connects the reference electrode 215. A pair of element fixing portions 614 that are electrically connected to each other, a distal end extending portion 63 that extends from the spine portion 610 toward the distal end in the axial direction, and the heater 4 that is formed in the distal end extending portion 63 is connected in the radial direction of the gas sensor 1. And a pressing portion that presses from the spine portion 610 side to the opening portion 619 side.
The gripping part 613 and the element fixing part 614 have an opening part 619 whose side face facing the spine part 610 opens in the same direction. The element fixing portion 614 has a protrusion 618 that protrudes from the opening 619 toward the spine 610.

Hereinafter, the gas sensor 1 of this example will be described in detail.
As shown in FIG. 1, the gas sensor 1 of the present example includes a housing 3, an insulator 5, a reference signal line 71, a measurement signal line 72, and the like in addition to the sensor element 2, the heater 4, and the heater holder 6 described above. . The housing 3 supports and fixes the sensor element 2 in the measured gas flow path. The insulator 5 is made of an insulating material that inserts and holds the base end portion 41 of the heater 4. The reference signal line 71 is electrically connected to the reference electrode 215 of the sensor element 2 via the heater holder 6, and the measurement signal line 72 is electrically connected to the measurement electrode 225 via a terminal and a lead described later. Conduct.

As shown in FIG. 1, in the gas sensor 1, the sensor element 2 is held inside a cylindrical housing 3.
The sensor element 2 includes, for example, a solid electrolyte body 20 formed in a bottomed cylindrical shape whose end is closed with an oxygen ion conductive material such as zirconia, a reference electrode 215 formed on the inner surface 21, and an outer surface 22. Measurement electrode 225. A solid electrolyte body engaging portion 201 having a large diameter is formed in the middle of the solid electrolyte body 20.

A metal heater holder 6 is inserted into the solid electrolyte body 20.
In this example, as shown in FIGS. 1 to 6, the heater holder 6 includes a substantially cylindrical main body 61 that partially grips the heater 4 and partially covers the heater 4, and extends from the main body 61 to the proximal end side. And a terminal portion 62 that is electrically connected to the reference-side signal line 71. The terminal portion 62 is formed in a substantially cylindrical shape having an open side surface so that a reference side signal line 71 extending from the reference side of the gas sensor 1 is inserted and held at the base end side. 2 is a side view of the heater holder holding the heater inside, and FIGS. 3A to 3E are AA line, BB line, CC line, D in FIG. 2, respectively. It is a figure which shows the cross-sectional shape when the cross section of the -D line and the EE line is seen by the arrow.

The main body 61 of the heater holder 6 includes an insertion portion 611, a locking portion 612, a grip portion 613, and an element fixing portion 614 in order from the proximal end side to the distal end side. Specifically, the main body 61 includes a spine portion 610 extending in the axial direction, a pair of insertion portions 611 extending from the spine portion 610 toward the heater 4 in a direction substantially perpendicular to the axial direction, and an axial direction substantially perpendicular to the axial direction. A pair of grip portions 613 extending from the spine portion 610 to the heater side, a pair of element fixing portions 614 extending from the spine portion 610 to the heater side in a direction substantially perpendicular to the axial direction, and a pair extending from the spine portion 610 in the radial direction of the gas sensor 1. And a locking portion 612. The insertion part 611, the grip part 613, the element fixing part 614, and the locking part 612 have an opening part 619 whose side face facing the spine part opens in the same direction. In addition, the latching | locking part 612 is formed so that it may extend in the direction opposite to the heater 4 side from the backbone part 610, and the heater 4 side is necessarily opened. That is, the main body 61 of the heater holder 6 has a substantially C-shaped cross section in the radial direction of the gas sensor.
The element fixing portion 614 is formed with a protrusion 618 that protrudes from the opening 619 toward the spine 610. The protrusion 618 is formed by turning back the end of the element fixing portion 614 on the opening 619 side toward the heater 4 (see FIGS. 2 to 4).
The main body 61 of the heater holder 6 has a distal end extending portion 63 that extends from the spine 610 to the distal end in the axial direction. A pressing portion 635 that presses the heater 4 in the radial direction of the gas sensor 1 is formed on the distal end side of the distal end extending portion 63.

  As shown in FIGS. 1 to 6, in the gas sensor 1, the heater holder 6 is inserted into the solid electrolyte body 20 from the distal end side in a state where the heater 4 is held by the holding portion 613. The heater holder 6 is fitted inside the solid electrolyte body 20 at the element fixing portion 614. The heater holder 6 is electrically connected to a reference electrode 215 formed on the inner surface 21 of the solid electrolyte body 20 at the element fixing portion 614. The measurement electrode 225 formed on the outer surface of the solid electrolyte body 20 is electrically connected to the measurement-side intermediate lead 721 extending to the base end side.

The heater 4 is assembled to the main body 61 of the heater holder 6. The heater 4 is held by a holder at a holding portion 613 of the heater holder 6, and the heater 4 is fixed to the heater holder 6.
The heater 4 includes a heater base formed of a ceramic material such as alumina in the shape of a long axis, a heating element (not shown) built in the tip, and a pair of lead wires (not shown) connected to the heating element. And a pair of heater electrodes 45 formed on the surface of the heater substrate and respectively conducting to the pair of lead wires.
The heater 4 is inserted into the sensor element 2 and is elastically fixed by a grip portion 613 of the heater holder 6.

Moreover, as shown in FIG. 6, the pressing part 635 of the heater holder 6 presses the side surface of the heater 4 in the radial direction of the gas sensor. Thereby, the front end portion 42 of the heater 4 is in contact with the inner side surface 21 of the solid electrolyte body 20.
As shown in FIGS. 6, 7 </ b> A and 7 </ b> B, the heater 4 is pressed in the heater holder 6 in the direction 199 from the spine 610 toward the opening 619 by the pressing portion 635. Then, the side surface of the heater 4 comes into contact with the protrusion 618 provided on the element fixing portion 614 of the heater holder 6. That is, in the heater holder 6, even if the heater 4 is stressed in the direction 199 from the backbone to the opening in the radial direction due to pressing or vibration by the pressing portion 635, the protrusion 618 becomes a fulcrum of this stress. It is configured. FIGS. 7A and 7B are views of the heater holder that holds the heater as viewed from the axial direction of the sensor, and the configuration other than the holding portion and the element fixing portion of the heater holder is omitted.

  As shown in FIG. 1, the housing 3 is formed with a housing engaging portion 31, and the solid electrolyte body engaging portion 201 and the housing engaging portion 31 are connected via a metal buffer member (not shown). The sensor element 2 is engaged and locked in the housing 3. Further, in the gap between the sensor element 2 and the housing 3, for example, an insulating powder 101 such as talc, an insulating powder molded body 102, an insulating sealing member 103 such as ceramic or glass, a spacer made of a metal member The sensor element 2 is filled with an element fixing member 104, and the housing caulking portion 32 at the upper edge of the housing 3 is caulked to fix the sensor element 2 in the housing 3.

An element cover 12 that protects the sensor element 2 is fixed to the front end side of the housing 3. The element cover 12 has a double structure in which two covers of an inner cover 121 and an outer cover 122 are arranged in parallel. The inner cover 121 and the outer cover 122 are formed with measured gas inlets 127 and 128 for introducing the measured gas into them, respectively.
As a result, the gas to be measured flowing through the exhaust system of the internal combustion engine is introduced into the gas chamber 120 to be measured formed inside the element cover 12 and around the sensor element 2 through the gas introduction ports 127 and 128. be able to.

As shown in FIG. 1, the gas sensor 1 includes, on the proximal end side, a reference side signal line 71 and a measurement side signal line 72 connected to an external circuit, an insulator 5, an insulator holding metal fitting 50, and a reference gas side cover 13. Are arranged.
The reference gas side cover 13 is fixed to the proximal end side of the housing 3 and forms a reference gas space 130 on the inner side. In other words, the opening on the front end side of the reference gas side cover 13 is welded to the cover fixing portion 34 disposed on the radially outer side of the caulking portion 32 in the housing 3. The base end portion of the reference gas side cover 13 is sealed with a rubber bush 16. The reference signal line 71 and the measurement signal line 72 connected to the external circuit are insulated and supported by the rubber bush 16.

  As shown in FIG. 1, the insulator 5 is made of an insulating material, has a columnar main body portion 56, and a substantially cylindrical protrusion 57 extending from the base end side end surface 561 of the main body portion 56 to the base end side, and has a cross section. It is a substantially convex member. An insertion hole 51 for inserting and holding the proximal end portion of the heater is provided on the distal end side end surface 562 of the insulator 5 in the axial direction. The insertion hole 51 does not penetrate the insulator 5 and is closed so that the base end portion of the heater abuts inside the insulator 5. The insulator 5 has a reference-side terminal hole 52 into which a terminal portion 62 (see FIGS. 1, 2, and 4) extending from the main body portion 61 of the heater holder 6 to the proximal end side in the axial direction is inserted, and a measurement-side intermediate portion. A measurement side terminal hole 53 into which a measurement side terminal 722 (see FIG. 1) connected to the lead 721 is inserted is formed on the outer side in the radial direction than the insertion hole 51. The reference side terminal hole 52 and the measurement side terminal hole 53 penetrate the body portion 56 of the insulator 5 in the axial direction. The insulator 5 is formed with a pair of heater lead holes (not shown) into which a pair of lead portions 451 extending from the heater electrode 45 and projecting in the axial direction are inserted at the base end portion 41 of the heater 4. The heater lead hole is integrated with the insertion hole 51 on the tip portion 562 side of the insulator, and the protrusion 57 is formed by a hole independent of the insertion hole 51. The heater lead hole passes through the main body portion 56 and the protruding portion 57 in the axial direction.

  As shown in FIG. 1, the insulator 5 is fixed in the reference gas side cover 13 by a holding metal fitting 50. And the base end part 41 of the heater 4 is inserted in the insertion hole 51 of the insulator 5 with the insertion part 611 of the heater holder 6.

As shown in FIGS. 1-5, the insertion part 611 formed in the base end side of the main-body part of the heater holder 6 is inserted in the insertion hole 51 of the insulator 5 with the base end part of the heater. The heater holder 6 is fixed to the insulator 5 by fitting the insertion portion 611 of the heater holder 6 with the insertion hole 51 of the insulator 5. Further, the engaging portion 612 of the heater holder 6 is in contact with the tip end surface 562 of the insulator 5. Thereby, the length of the heater holder 6 inserted in the insertion hole 51 is adjusted.
A pair of lead portions 451 extending from a pair of heater electrodes 45 formed on the base end side of the outer peripheral portion of the heater 4 are inserted into the heater lead holes. These lead portions 451 are connected to a heater power supply lead 49 extending from an external power supply (not shown) so that power can be supplied to the heater 4 from the external power supply.

A reference side terminal 62 that is integrally connected to the main body of the heater holder 6 is inserted into the reference side terminal hole 52 of the insulator 5. The reference terminal 62 is electrically connected to a reference signal line 71 extending from the base end side of the gas sensor 1.
A measurement-side terminal 722 is inserted into the measurement-side terminal hole 53 of the insulator 5. The measurement side terminal 722 is formed by forming an elastic metal material into a substantially U-shaped spring shape. The measurement side terminal 722 is electrically connected to the measurement side intermediate lead 721 on the distal end side as described above, and is electrically connected to the measurement side signal line 72 extending from the proximal end side of the gas sensor 1 on the proximal end side. Has been.

  As shown in FIG. 1, a caulking cover 14 is disposed on the outer peripheral side of the reference gas side cover 13, and the caulking cover 14 is caulked and fixed to the reference gas side cover 13. In addition, the caulking cover 14 is formed with a reference gas introduction port 141 for introducing a reference gas into the reference gas space 130.

  Note that the reference gas is the atmosphere, and the atmosphere flowing in from the reference gas inlet 141 passes through the reference gas space 130 in the reference gas side cover and flows into the reference gas chamber 20 in the sensor element.

Next, in the gas sensor 1 of this example, a method for assembling the heater to the heater holder will be described.
In this example, as shown in FIG. 4, FIG. 8A and FIG. 8B, the main body 61 of the heater holder 6 includes a spine 610 extending in the axial direction and a spine portion on the heater 4 side in a direction substantially perpendicular to the axial direction. A pair of insertion portions 611 extending from 610, a pair of gripping portions 613, and a pair of element fixing portions 614 are provided. Further, the main body 61 has a pair of locking portions 612 extending from the spine portion 610 in the radial direction of the gas sensor. The insertion portion 611, the grip portion 613, the element fixing portion 614, and the locking portion are open in the same direction on the side surface facing the spine portion.

  Therefore, the heater 4 can be assembled to the heater holder 6 by inserting the heater 4 from the side surface through the opening side 619 of the heater holder 6 (an assembling process). Thereby, the assembly 4 can be obtained by assembling the heater 4 to the heater holder 6 (see FIG. 8B).

  Next, as shown in FIG. 6, the assembly 400 is inserted and disposed in the solid electrolyte body 20 of the sensor element 2 (insertion step). In the inserting step, the assembly body 400 is inserted and arranged in the solid electrolyte body 20 of the sensor element 2, whereby the element fixing portion 614 of the heater holder 6 is pressed by the inner surface 21 of the solid electrolyte body 20, and a pair of element fixings are performed. The distance D between the portions 614 (the distance D between the openings 619 in the element fixing portion 614) can be reduced (see FIGS. 6, 7A, and 7B). Then, the side surface of the heater 4 is brought into contact with the protrusion 618 in the element fixing portion 614 of the heater holder 6 (see FIG. 7B). Moreover, the front end portion 42 of the heater pressed in the radial direction of the gas sensor by the pressing portion 635 of the heater holder 6 is brought into contact with the inner side surface 21 of the solid electrolyte body 20 (see FIG. 6).

Hereinafter, the effect of the gas sensor 1 of this example is demonstrated using FIGS.
In the gas sensor 1 of this example, as described above, the grip portion 613 and the element fixing portion 614 of the heater holder 6 have the opening portion 619 whose side surface facing the spine portion 610 opens in the same direction. That is, the side surface of the main body 61 of the heater holder 6 opens in the same direction. Therefore, in the gas sensor, when the heater 4 is assembled to the heater holder 6, the heater 4 can be assembled from the side surface through the opening 619 of the heater holder 6 (see FIGS. 8A and 8B). Therefore, the heater 4 can be easily assembled to the heater holder 6.

  In addition, the element fixing portion 614 of the heater holder 6 is formed with a protrusion 618 that protrudes from the opening 619 to the spine 610 side. Therefore, even if the pressing portion 635 presses the heater 4 from the side surface in the radial direction of the gas sensor 1, the protrusion 618 becomes a fulcrum of stress by the pressing portion 635, and the heater 4 is detached from the opening 619 of the heater holder 6. Can be prevented. Therefore, the heater 4 can be prevented from being detached from the opening 619 of the heater holder 6 even during vibration.

In this example, the protrusion 618 is formed by folding the end of the element fixing portion 614 on the opening 619 side toward the heater 4.
Therefore, the protrusion 618 can be easily formed.

Further, the front end portion 42 of the heater 4 and the inner side surface 21 of the solid electrolyte body 20, and the side surface of the heater 4 and the protrusion 618 in the element fixing portion 614 are in contact with each other.
The heater 4 can be fixed to the solid electrolyte body 20 by bringing the front end portion 42 of the heater 4 into contact with the inner surface 21 of the solid electrolyte body 20 (see FIG. 6). Therefore, vibration resistance can be improved.
Further, by bringing the side surface of the heater 4 into contact with the protrusion 618 in the element fixing portion 614 of the heater holder 6, the protrusion 618 serves as a fulcrum of stress that the pressing portion 635 presses the side surface of the heater 4. The pressing stress generated at the tip portion 42 can be stabilized.
Further, in this example, the protrusion 618 and the side surface of the heater 4 are brought into contact with each other, but a gap may be provided therebetween. In this case, when the heater 4 moves in the radial direction at the time of vibration or the like, it is possible to prevent the side surface of the heater 4 from coming into contact with the protrusion, and the heater 4 from being detached from the heater holder 6.

Next, in the gas sensor manufacturing method of this example, the assembly process and the insertion process are performed.
As shown in FIG. 8A, in the assembly process, the heater 4 is inserted from the side through the opening 619 of the heater holder 6. As a result, as shown in FIG. 8B, the assembly 400 can be produced by assembling the heater 4 to the heater holder 6 by causing the grip 611 of the heater holder 6 to grip the side surface of the heater 4.

  Further, in the inserting step, as shown in FIG. 6, the assembly 400 is inserted and arranged in the solid electrolyte body 200 of the sensor element 2. Then, the tip end portion 42 of the heater 4 pressed in the radial direction of the gas sensor 1 by the pressing portion 635 of the heater holder 6 is brought into contact with the inner side surface 21 of the solid electrolyte body 20. At this time, the heater 4 receives stress from the spine 610 side of the heater holder 6 in the radial direction to the opening 619 side by the pressing portion 635 of the heater holder. In this example, as described above, the protrusion 618 is formed on the element fixing portion 614 of the heater holder, and this protrusion 618 serves as a fulcrum of stress by the pressing portion 635. Therefore, it is possible to prevent the heater 4 from being detached from the opening 619 of the heater holder 6.

  Further, in this example, the element fixing portion 614 of the heater holder 6 is pressed by the inner surface 21 of the solid electrolyte body 200 by inserting the assembly 400 into the solid electrolyte body 200 of the sensor element 2 (FIG. 6). The distance D between the pair of element fixing portions 614 is reduced (see FIGS. 7A and 7B). Therefore, in the above assembly process, the distance between the pair of element fixing portions 614 can be increased (see FIG. 7A), so that it is possible to avoid difficulty in assembling the heater 4 to the heater holder 6. .

  Thus, according to this example, it is possible to provide a gas sensor that can be easily assembled to the heater holder, has excellent vibration resistance, and can prevent the heater from being detached from the heater holder, and a method for manufacturing the same.

(Example 2)
This example is an example of a gas sensor in which the shape of the heater holder is different from that of the first embodiment. In the first embodiment, the element fixing portion 614 of the heater holder 6 has a protrusion extending along the axial direction of the sensor (see FIG. 5). In this example, the end portion on the opening side of the element fixing portion. A part of the protrusion was partially protruded toward the heater to form a protrusion 818 (see FIG. 9).

As shown in FIG. 9, in the heater holder body 81 of this example, the insertion part 811, the locking part 812, the grip part 813, the element fixing part 818, the tip extending part 83, A pressing portion 835 is formed.
A part of the end of the element fixing portion 818 on the opening side (the front side in FIG. 9) is bent from the opening side toward the spine side (from the front side to the back side of the paper surface) to form a protrusion 818. Yes. In the heater holder of this example, the side surface of the heater (not shown) can be pressed by a point instead of a surface or a line by the protrusion. In this case, the pressing force by the pressing portion 835 of the heater holder 6 can be further stabilized.
Other configurations and operational effects are the same as those of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Gas sensor 2 Sensor element 3 Housing 4 Heater 5 Insulator 6 Heater holder 613 Gripping part 614 Element fixing | fixed part 635 Pressing part

Claims (5)

It consists of an ion-conductive solid electrolyte body formed with a bottomed cylinder, a reference electrode in contact with the reference gas is formed on the inner surface, and a measurement electrode in contact with the measured gas on the outer surface. A sensor element for detecting the concentration of a specific gas;
A heater inserted and arranged in the sensor element;
At least a metal heater holder that grips the heater and fixes the heater to the sensor element and is electrically connected to the reference electrode of the sensor element,
The heater holder includes a backbone portion extending in the axial direction, a pair of gripping portions formed to extend toward the heater in a direction substantially perpendicular to the axial direction, and the heater in the direction substantially perpendicular to the axial direction. A pair of element fixing portions formed so as to extend to the side, contacting the inner surface of the solid electrolyte body in the sensor element, fixing the heater holder to the sensor element, and electrically conducting to the reference electrode; A distal end extending portion that extends from the spine to the distal end side in the axial direction; and a pressing portion that is formed on the distal end extending portion and presses the heater in the radial direction of the gas sensor.
The grip part and the element fixing part have an opening part whose side face facing the spine part opens in the same direction,
The gas sensor according to claim 1, wherein the element fixing portion is formed with a protrusion protruding from the opening toward the spine.   2. The gas sensor according to claim 1, wherein the projecting portion of the element fixing portion is formed by folding an end of the element fixing portion on the opening side toward the heater.   3. The gas sensor according to claim 1, wherein the front end portion of the heater and the inner side surface of the solid electrolyte body, and the side surface of the heater and the protrusion in the element fixing portion are in contact with each other. Gas sensor. The method for manufacturing a gas sensor according to any one of claims 1 to 3, wherein the heater is assembled to the heater holder by inserting the heater from the side through the opening of the heater holder. Assembly process;
The assembly is inserted and arranged in the solid electrolyte body of the sensor element, and the tip of the heater pressed in the radial direction of the gas sensor by the pressing portion of the heater holder is brought into contact with the inner side surface of the solid electrolyte body. A gas sensor manufacturing method comprising: an insertion step of contacting the gas sensor.   5. The manufacturing method according to claim 4, wherein, in the insertion step, the assembly is inserted into the solid electrolyte body of the sensor element, thereby fixing the element of the heater holder by the inner surface of the solid electrolyte body. The method of manufacturing a gas sensor, wherein the portion is pressed to reduce the distance between the pair of element fixing portions.

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