JP3822219B2 - Gas sensor - Google Patents

Description

  The present invention is a gas sensor in which a plate-shaped or bottomed cylindrical sensor element is assembled to a metal shell or the like, and detects a specific gas component in a gas to be measured, such as an oxygen sensor, a full-range air-fuel ratio sensor, or a NOx sensor. The present invention relates to a gas sensor.

  In an internal combustion engine, it has hitherto been known that it is effective for energy saving, exhaust gas purification, and the like to detect oxygen concentration in exhaust gas to be measured and perform combustion control based on the detected information. Yes. As a gas sensor for detecting the oxygen concentration or the like in the exhaust gas, a gas sensor using a sensor element made of a solid electrolyte such as partially stabilized zirconia is known, and various improvements have been made.

  As a specific structure of such a gas sensor, a sensor element having a gas contact portion that contacts exhaust gas, a metal shell that holds the sensor element, an outer cylinder that is connected to the metal shell at its tip, and a sensor A plurality of electrode extraction terminals that are electrically connected to the element, a plurality of lead wires that are electrically connected to each of the electrode extraction terminals, and each of the electrode extraction terminals are housed inside the outer cylinder, It is known to include a separator that is positioned and insulates between these electrode lead terminals, and an elastic seal member having a lead wire insertion hole through which each lead wire is inserted. Among such gas sensors, the separator is formed so as to have, for example, a main body portion that houses a part of the lead wire, an electrode lead-out portion, and the like, and a flange portion that is larger in diameter than the main body portion. The outer cylinder includes a small diameter portion having an inner diameter larger than the outer diameter of the main body of the separator and smaller than the outer diameter of the flange portion, a large diameter portion having an inner diameter larger than the outer diameter of the flange portion, a small diameter portion, and a large diameter portion. It is formed so as to have a step portion connecting the diameter portion.

The separator has one surface of the flange portion in contact with the step portion of the outer cylinder, and the other surface of the flange portion is pressed and fixed by an elastic member (biasing member) press-fitted into the large diameter portion of the outer cylinder. By doing so, it is held inside the outer cylinder. That is, the separator is sandwiched and fixed between the elastic member and the step portion of the outer cylinder (see, for example, Patent Documents 1 and 2).
JP 2001-147213 A JP 2001-311713 A

  However, the gas sensors described in Patent Literature 1 and Patent Literature 2 are configured to be sandwiched between the elastic member and the step portion of the outer cylinder in a state where the flange portion of the separator is in contact with the step portion of the outer tube. Therefore, when a stepping stone or the like collides with an outer surface corresponding to a portion of the outer cylinder that comes into contact with one surface of the collar portion, the compressive stress due to the collision is directly transmitted to the separator. Therefore, the gas sensors described in Patent Document 1 and Patent Document 2 have a problem that the separator is easily damaged when a stepping stone or the like collides with the outer cylinder.

  Further, in a gas sensor using a plate-like sensor element, a structure in which an electrode terminal portion is sandwiched and fixed between the sensor element and the separator is often employed. For this reason, if the separator is in contact with the outer cylinder, if a stepping stone or the like collides with the outer surface of the outer cylinder, the compressive stress due to the collision is directly transmitted to the separator. There is a problem that occurs.

  The present invention has been made to solve the above-described problems, and can prevent damage to the separator even when an impact is applied from the outside of the outer cylinder, and the separator can be stably held in the outer cylinder. An object is to provide a simple gas sensor.

In order to achieve the above object, in the gas sensor according to claim 1, the sensor element that extends in the axial direction and whose tip side is exposed to the gas to be measured, the metal shell that holds the sensor element, and the tip part of the sensor An outer cylinder connected to the metal shell, a plurality of electrode extraction terminals electrically connected to the sensor element, a plurality of lead wires connected to each of the electrode extraction terminals, and the inside of the outer cylinder, and each position of its own internal electrode extraction terminal, a separator insulating the electrode extraction pins, has a lead wire insertion hole, each lead wire therein inserted, to the rear side of the separator out of the outer cylinder A separator, wherein the separator is in contact with the distal end surface of the elastic seal member without contacting the outer peripheral surface of the separator with the inner peripheral surface of the outer cylinder. Is held in the outer tube in a state of being urged to the end side, further separator, and a rear end side portion positioned on the rear end side, a distal end portion located on the distal end side, and the rear side A flange portion that is located in the middle of the distal end side portion and has a larger diameter than the rear end side portion and the distal end side portion and includes a distal end side surface facing the distal end side between the distal end side portion and the flange portion. The urging member that urges the pressing force from the tip side surface of the elastic seal member toward the tip surface of the elastic seal member is urged toward the rear end side in contact with the tip surface of the elastic seal member, and the elastic seal member It is clamped between the urging members .

Further, in the gas sensor of the invention according to claim 2, in addition to the configuration of the invention of claim 1, the urging member is disposed on the outer periphery of the front end side portion of the separator , and the urging member among the outer cylinders. The separator is deformed so as to urge the separator toward the rear end side by a deformed portion that is deformed so as to be convex inward by pressing a portion located on the radially outer side. .

In the gas sensor of the invention according to claim 3, in addition to the configuration of the invention of claim 1 or 2, the sensor element has a plate shape and a plurality of electrode terminal portions on the front and back surfaces on the rear end side. The electrode extraction terminal is sandwiched and fixed between the separator and the sensor element in a state of being in contact with one of the electrode terminal portions of the sensor element, and the electrode extraction terminal and the electrode terminal portion of the sensor element are The contact part and the support part of the separator by the urging member are at positions shifted when viewed along the axial direction of the gas sensor .

Further, in the gas sensor of the invention according to claim 4, in addition to the configuration according to any one of claims 1 to 3 , when the outer peripheral surface of the separator and the inner peripheral surface of the outer cylinder are viewed in the radial direction, It is characterized by being separated by 0.5 mm or more .

In addition, in the gas sensor of the invention according to claim 5, in addition to the configuration of the invention according to any one of claims 1 to 4, the rear end surface of the separator is formed so as to be recessed radially inward from the periphery, The separator is characterized in that it is held by the outer cylinder so that the peripheral side of the rear end surface is in contact with the front end surface of the elastic seal member .

  According to the gas sensor of claim 1, each of the plurality of electrode extraction terminals electrically connected to the sensor element is located inside, and the separator for insulation between the electrode extraction terminals is provided inside the outer cylinder. And it is accommodated in the front end side from the elastic seal member in which the lead wire insertion hole is formed. And this separator is hold | maintained inside an outer cylinder in the state in which the outer peripheral surface of itself is non-contact with respect to the internal peripheral surface of an outer cylinder. In other words, in the present invention, the separator is accommodated inside the outer cylinder with a gap between the separator and the inner peripheral surface of the outer cylinder. Thereby, even when a stepping stone collides with the outer cylinder, the compressive stress due to the impact can be released by the gap. Therefore, even if an impact is applied from the outside of the outer cylinder, the impact is not directly transmitted to the separator, and the separator can be prevented from being damaged.

  Furthermore, according to the gas sensor of the first aspect, when the separator is held in the outer cylinder in a non-contact state with respect to the inner peripheral surface of the outer cylinder as described above, the separator has the lead wire insertion hole. The elastic seal member is held in a state of being urged toward the rear end side while being in contact with the front end surface of the elastic seal member. As described above, in the present invention, the separator is brought into contact with the elastic seal member and is elastically held, so that even if an external shock is applied to the outer cylinder, the elastic seal member alleviates or absorbs the shock. Can be prevented from swinging in the outer cylinder. Therefore, in the present invention, the separator can be stably held in the outer cylinder when the gas sensor is used while the separator is held in a non-contact state with respect to the inner peripheral surface of the outer cylinder.

  In this gas sensor, the shape of the sensor element is not particularly limited, and examples thereof include a bottomed cylindrical shape and a plate shape. For the biasing of the separator, any mechanism (biasing member) that biases the separator toward the rear end can be employed. For example, a ring-shaped metal plate formed with a gear-shaped protruding claw portion on the outer periphery is press-fitted into the outer cylinder, the claw portion is pressed against the inner peripheral surface of the outer cylinder, and the separator is urged toward the rear end side. be able to.

  As the separator, any member having little deterioration at the use temperature and having an insulating property can be applied. Examples thereof include ceramics such as alumina and silicon nitride, and engineer plastics such as polyether ether ketone (PEEK), polyether ketone (PEK), and polyphenylene sulfide (PPS). The insulating seal member can be exemplified by a rubber material having heat resistance such as fluorine rubber or silicon rubber.

Further , the separator is elastically sealed by using a biasing member that exerts a pressing force (biased) from the distal end side surface of the collar portion toward the distal end surface of the elastic seal member while forming the separator in the specific shape described above. The front end surface of the member is urged and held between the elastic seal member and the urging member. Thus, by holding the separator using the biasing member, the separator can be stably held in the outer cylinder.

Furthermore, according to the gas sensor according to claim 2 , the urging member is disposed on the outer periphery of the front end side portion of the separator, and a portion of the outer cylinder that is located on the radially outer side of the urging member is arranged in the radial direction. The separator is deformed so as to be urged toward the rear end side by a deforming portion that is pressed inward and deformed to be convex inward. Here, as the urging member that urges the separator toward the rear end side, it is possible to adopt a mechanism in which the separator is held by the outer cylinder by being press-fitted into the inner peripheral surface of the outer cylinder as in the past, It is difficult to say that it is easy to press-fit the urging member between the separator (specifically, the front end side portion of the separator) and the outer cylinder in the assembly process of the gas sensor. Therefore, in the present invention, the urging member is also deformed so that the urging member urges the separator toward the rear end side by forming a deformed portion that protrudes inward from the outside of the metal outer cylinder. is doing. Thus, the separator can be easily urged to the rear end side using the urging member, and the separator can be stably held in the outer cylinder, so that a low-cost gas sensor can be obtained.

Furthermore, in the gas sensor according to claim 3 , a sensor element having a plate shape and having a plurality of electrode terminal portions on the front and rear surfaces on the rear end side is used. In a state of being in contact with the sword, it is clamped and fixed between the separator and the sensor element.
By the way, in the gas sensor of the present invention, the urging member is used to urge the separator toward the rear end side so as to contact the front end surface of the elastic member. The seal member can mitigate or absorb the impact and suppress the swing of the separator. However, depending on the degree of the impact, the separator may swing not only with the support portion of the separator by the urging member as a fulcrum. is there. Here, if the supporting portion of the separator by the urging member and the contact portion between the electrode take-out terminal and the electrode terminal portion of the sensor element coincide with each other when viewed along the axial direction of the gas sensor, When the separator swings with the support portion of the separator supported by a member as a fulcrum, the stress caused by the swinging of the separator is easily applied to the contact portion between the electrode extraction terminal and the electrode terminal portion of the sensor element, and the plate-like sensor element There is a possibility that defects such as cracks and breaks may occur.

On the other hand, in the gas sensor of the present invention, the contact portion between the electrode take-out terminal and the electrode terminal portion of the sensor element and the support portion of the separator by the biasing member are shifted when viewed along the axial direction of the gas sensor. It is set to be placed at the position. As a result, even if the separator swings with the support portion of the separator by the urging member as a fulcrum, the stress due to the swinging of the separator does not easily reach the contact portion, and problems such as breakage of the sensor element occur. Can be effectively suppressed.
If the contact portion between the electrode lead-out terminal and the electrode terminal portion of the sensor element and the support portion of the separator by the urging member are arranged at positions shifted when viewed along the axial direction of the gas sensor, Although the positional relationship is not particularly limited, from the viewpoint of effectively obtaining a biasing force toward the rear end side of the separator by the biasing member, the support portion is located on the rear side when viewed along the axial direction of the gas sensor rather than the contact portion. It is preferable to be located at.

According to the gas sensor of the fourth aspect, the outer peripheral surface of the separator and the inner peripheral surface of the outer cylinder are separated by 0.5 mm or more when viewed in the radial direction. As a result, even when a stepping stone or the like collides with the outer cylinder and the outer cylinder itself is deformed, the inner peripheral surface of the outer cylinder becomes difficult to touch the outer peripheral surface of the separator, thereby further preventing the separator from being damaged. it can.

Furthermore, according to the gas sensor of the fifth aspect, the rear end surface of the separator is formed in a shape that is recessed from the periphery toward the inside in the radial direction. In addition, “a form that is recessed radially inward from the periphery” refers to a state in which the rear end surface of the separator is dented from the periphery toward the center, such as a spherical shape, a cone shape, or a pyramid shape. Specifically, a form in which the rear end surface is recessed in a spherical shape or a conical shape can be exemplified. And in this invention, such a separator is urged | biased to the rear-end side, and the peripheral edge side of the rear-end surface of a separator is made to contact the front-end | tip surface of an elastic seal member. With such a configuration, even when the elastic seal member undergoes thermal expansion during use of the gas sensor, the front end side of the expanded elastic seal member can escape to the rear end face side of the separator. Therefore, according to the present invention, it is possible to effectively suppress the occurrence of damage due to restraint (compression) by the separator even when the elastic seal member undergoes thermal expansion.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
In this embodiment, it is a kind of gas sensor, and detects a specific gas (specifically, oxygen concentration) in exhaust gas to be measured for use in air-fuel ratio feedback control in automobiles and various internal combustion engines. The full-range air-fuel ratio sensor 2 (hereinafter also referred to as the air-fuel ratio sensor 2) mounted on the exhaust pipe of the internal combustion engine will be described.

  FIG. 1 is a cross-sectional view showing the overall configuration of an air-fuel ratio sensor 2 according to an embodiment to which the present invention is applied. The air-fuel ratio sensor 2 includes a cylindrical metal shell 102 having a screw portion 103 formed on the outer surface for fixing to an exhaust pipe, a sensor element 4 having a plate shape extending in the axial direction (vertical direction in the figure), A cylindrical ceramic sleeve 6 disposed so as to surround the periphery of the sensor element 4 in the radial direction and the electrode terminal portions 30, 31, 32, 34, 36 of the sensor element 4 are electrically connected to form a current path. A lead frame 10, a separator 82 that is formed of an insulating material and is connected to the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4; A lead wire 46 that forms a current path between the frame 10 and the outside of the sensor is provided. The lead wire 46 is composed of a conductive core wire and an insulating resin coating material that covers the core wire, and is configured such that the front end side and the rear end side of the core wire are exposed from the resin coating material. Has been.

  The sensor element 4 has a plate-like shape extending in the axial direction, and a detection portion 8 covered with an electrode protection layer is formed on the front end side (downward in the figure) directed to the gas to be measured, and the rear end side ( Electrode terminal portions 30, 31, 32, 34, and 36 are formed on the first plate surface 21 and the second plate surface 23, which are front and back, of the outer surface (upper in the drawing). Since the lead frame 10 is disposed between the sensor element 4 and the separator 82, the lead frame 10 contacts and is electrically connected to the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4. The lead frame 10 is also electrically and mechanically connected to a lead wire 46 disposed inside the sensor from the outside, and an external device (for example, ECU) to which the lead wire 46 is connected and an electrode A current path for a current flowing between the terminal portions 30, 31, 32, 34, and 36 is formed.

  The metal shell 102 has a through-hole 109 penetrating in the axial direction, and has a substantially cylindrical shape having a shelf 107 protruding radially inward inside the through-hole 109. Further, the metal shell 102 has the detection portion 8 disposed outside the front end side of the through hole 109 and the electrode terminal portions 30, 31, 32, 34, 36 disposed outside the rear end side of the through hole 109. The sensor element 4 inserted through 109 is held. Further, the shelf 107 is formed as an inwardly tapered surface having an inclination with respect to a plane perpendicular to the axial direction.

  In addition, inside the through hole 109 of the metal shell 102, an annular ceramic holder 106, a powder filling layer 108 (hereinafter also referred to as a talc ring 108), and an auxiliary sleeve 110, surrounding the sensor element 4 in the radial direction. The second powder filling layer 111 and the ceramic sleeve 6 described above are laminated in this order from the front end side to the rear end side. Further, a caulking ring 112 is disposed between the ceramic sleeve 6 and the rear end portion 104 of the metal shell 102, and the rear end portion 104 of the metal shell 102 is interposed via the caulking ring 112. It is crimped so as to press against the tip side.

  Further, a protective cover 129 that functions as a packing for maintaining airtightness is disposed between the ceramic holder 106 and the shelf 107 of the metal shell 102. The protective cover 129 is made of a metal material (for example, stainless steel) and has a bottom surface portion that covers the side surfaces of the ceramic holder 106, the talc ring 108, and the auxiliary sleeve 110 and covers the peripheral edge portion of the ceramic holder 106. It is formed in a cylindrical shape. The bottom surface of the protective cover 129 has a central opening having a size that allows the sensor element 4 to be inserted through the central portion.

  Here, a perspective view showing a schematic structure of the sensor element 4 is shown in FIG. In FIG. 2, the sensor element 4 is shown by omitting an intermediate portion in the axial direction. The sensor element 4 is formed by laminating an element portion 20 formed in a plate shape extending in the axial direction (left and right direction in FIG. 2) and a heater 22 formed in a plate shape extending in the axial direction. It is formed in a plate shape having a cross section. Since the sensor element 4 used as the air-fuel ratio sensor 2 is a conventionally known sensor element, a detailed description of its internal structure and the like is omitted, but the schematic configuration is as follows.

  First, the element unit 20 includes an oxygen concentration cell element in which a porous electrode is formed on both sides of a solid electrolyte substrate, an oxygen pump element in which a porous electrode is formed on both sides of the solid electrolyte substrate, and a gap between these elements. The spacers are stacked to form a hollow measurement gas chamber. This solid electrolyte substrate is made of zirconia in which yttria is dissolved as a stabilizer, and the porous electrode is mainly made of Pt. The spacer forming the measurement gas chamber is mainly composed of alumina, and inside the hollow measurement gas chamber is one porous electrode of the oxygen concentration cell element and one porous electrode of the oxygen pump element. It arrange | positions so that an electrode may be exposed. The measurement gas chamber is formed so as to be positioned on the distal end side of the element portion 20, and a diffusion rate controlling portion made of porous ceramic for communicating the measurement gas chamber and the outside is provided on the distal end side of the spacer. The portion where the measurement gas chamber is formed corresponds to the detection unit 8. On the other hand, the heater 22 is formed by sandwiching a heating resistor pattern mainly composed of Pt between insulating substrates mainly composed of alumina. The element unit 20 and the heater 22 are joined to each other via a ceramic layer (for example, zirconia ceramic or alumina ceramic). The sensor element 4 has an electrode protective layer (not shown) made of porous ceramic for preventing poisoning on at least the surface of the electrode exposed to the measurement object (exhaust gas in the present embodiment) on the tip side. Is formed. In the present embodiment, the entire front end side including the surface of the electrode exposed to the exhaust gas in the sensor element 4 is covered with the electrode protective layer.

  In such a sensor element 4, as shown in FIG. 2, three electrode terminal portions 30, 31, 32 are formed on the rear end side (right side in FIG. 2) of the first plate surface 21, and the second plate surface Two electrode terminal portions 34 and 36 are formed on the rear end side of 23. The electrode terminal portions 30, 31, and 32 are formed in the element portion 20, and one electrode terminal portion is one porous electrode of the oxygen concentration cell element exposed to the inside of the measurement gas chamber and the oxygen pump element. Are electrically connected in common with one of the porous electrodes. The remaining two electrode terminal portions of the electrode terminal portions 30, 31, and 32 are electrically connected to the other porous electrode of the oxygen concentration cell element and the other porous electrode of the oxygen pump element, respectively. The electrode terminal portions 34 and 36 are formed in the heater 22 and are respectively connected to both ends of the heating resistor pattern through vias (not shown) that cross in the thickness direction of the heater.

  As shown in FIG. 1, the sensor element 4 configured in this way protrudes from the front end of the metal shell 102 fixed to the exhaust pipe with the detection unit 8 on the front end side (lower side in FIG. 1), and on the rear end side. The electrode terminal portions 30, 31, 32, 34, and 36 are fixed to the inside of the metal shell 102 in a state of protruding from the rear end of the metal shell 102. On the other hand, as shown in FIG. 1, a bottomed cylindrical external protector 42 having a plurality of holes and covering the protruding portion of the sensor element 4 on the outer periphery of the front end side (downward in FIG. 1) of the metallic shell 102 An internal protector 43 is attached by laser welding or the like.

An outer cylinder 44 made of a stainless steel alloy having a thickness of 0.5 mm is fixed to the outer periphery on the rear end side of the metal shell 102. As shown in FIG. 1, the outer cylinder 44 includes a first outer cylinder portion 54 joined to the metal shell 102, and a second outer cylinder located on the rear end side and having a smaller diameter than the first outer cylinder portion 54. A portion 56, a first step portion 49 positioned therebetween, a third outer cylinder portion 58 that is located on the rear end side of the second outer cylinder portion 56 and has a smaller diameter than the second outer cylinder portion 56 ; It has the 2nd step part 48 located between these. In the present embodiment, the outer cylinder 44 is disposed on the outer periphery of the rear end side of the metallic shell 102, and the overlapping portion of the outer cylinder 44 and the metallic shell 102 is directed from the outside of the outer cylinder 44 to the radially inner side. After the crimping, the entire portion is fixed to the metal shell 102 by performing laser welding on the entire circumference.

Further, the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4 are respectively connected to the opening portion on the rear end side of the outer tube 44 (in other words, inside the third outer tube portion 58 ). An elastic seal member 50 made of fluororubber is formed, in which a lead wire insertion hole 61 through which the five lead wires 46 are inserted and a protruding portion 53 that protrudes radially outward is formed.

  A separator 82 is disposed on the rear end side (upper side in FIG. 1) of the sensor element 4 protruding from the rear end portion 104 of the metal shell 102. In the present embodiment, the separator 82 is disposed so as to surround the periphery of the sensor element 4 in which the electrode terminal portions 30, 31, 32, 34, and 36 are formed.

  Here, as shown in FIG. 1, the separator 82 is held in the outer cylinder 44 with its outer peripheral surface being in non-contact with the inner peripheral surface of the outer cylinder 44. More specifically, the separator 82 is urged toward the rear end side so as to contact the front end surface 52 of the elastic seal member 50 by an urging metal fitting 200 described later, and the front end surface 52 of the elastic seal member 50 and the urging metal fitting 200 and is held in the outer cylinder 44 without contacting the inner peripheral surface of the outer cylinder 44. In the present embodiment, the outer peripheral surface of the separator 82 and the inner peripheral surface of the outer cylinder 44 are separated by 0.5 mm or more when viewed in the radial direction of the air-fuel ratio sensor 2, and the shortest distance S between them is 1 .5mm.

  Below, the separator 82 is demonstrated. FIG. 4 is a perspective view showing the appearance of the separator 82 when viewed from the front end side. As shown in FIGS. 1 and 4, the separator 82 is formed in a cylindrical shape having an insertion hole 84 that penetrates in the axial direction, and is located between the rear end side portion 303, the front end side portion 301, and between them. And a flange 83 having a diameter larger than these. As shown in FIG. 1, the rear end surface 305 of the separator 82 (specifically, the rear end side portion 30) is formed in a form that is recessed radially inward from the peripheral edge. More specifically, the rear end surface 305 is formed in a shape that is recessed in a spherical shape from the peripheral edge toward the insertion hole 84 located in the center.

  Then, on the inner wall surface of the insertion hole 84 facing the first plate surface 21 (not shown) of the sensor element 4, as shown in FIG. 4, first rib portions 87 projecting inward are formed at two locations. Has been. The first rib portion 87 is provided as a lead frame boundary portion in the insertion hole that forms the boundary of the three first frame arrangement grooves 86 for individually arranging the three lead frames 10 in an electrically insulated state. It has been. The three first frame arrangement grooves 86 are formed at positions corresponding to the electrode terminal portions 30, 31, and 32 on the first plate surface 21 of the sensor element 4.

  In addition, a second rib portion 89 projecting inward is formed at one location on the inner wall surface of the insertion hole 84 that faces the second plate surface 23 (not shown) of the sensor element 4. The second rib portion 89 is provided as a lead frame boundary portion in the insertion hole that forms a boundary between the two second frame arrangement grooves 88 for individually arranging the two lead frames 10 in an electrically insulated state. It has been. The two second frame arrangement grooves 88 are formed at positions corresponding to the electrode terminal portions 34 and 36 on the second plate surface 23 of the sensor element 4.

  The first rib portion 87 and the second rib portion 89 have a function of preventing the lead frames 10 arranged in the adjacent frame arrangement grooves from contacting each other, and the adjacent lead frames 10 are arranged. By preventing the current from conducting electrically, the current path can be prevented from becoming defective.

  Further, the separator 82 includes a first locking groove portion 90 and a second locking groove portion 91 formed on the distal end surface (the front side surface in the drawing) so as to be connected to the distal end side opening of the insertion hole 84. ing.

  The first locking groove portion 90 is formed in a substantially L shape when viewed from the front end side of the separator 82, and is formed so that a first frame locking portion 19 to be described later of the lead frame 10 can be disposed. The first locking groove 90 includes two locations connected to the two first frame arrangement grooves 86 formed at both ends of the three first frame arrangement grooves 86 and two second frame arrangement grooves 86. It is formed in two places connected to 88. The second locking groove 91 is a narrow groove 93 formed between the two ridges 92 and an enlarged width formed on the outer side in the radial direction from the narrow groove 93 of the front end surface of the separator 82. The groove portion 94 is formed so that a second frame locking portion 219 (to be described later) of the lead frame 10 can be disposed. In addition, the protruding item | line part 92 is formed in the shape which continues from the front-end | tip part of the 1st rib part 87. As shown in FIG. Further, the second locking groove portion 91 is formed at one place connected to one first frame arrangement groove 86 formed at the center among the three first frame arrangement grooves 86.

  Next, the urging metal fitting 200 will be described. As shown in FIG. 1, the urging metal fitting 200 is disposed around the front end side portion 301 of the separator 82. As shown in FIG. 6, the urging metal fitting 200 includes a cylindrical tube portion 201, a J-type holding portion 203 and a tube formed integrally with the tube portion 201 at the rear end portion 202 of the tube portion 201. A part extending portion 204 is provided. The urging metal fitting 200 shown in FIG. 6 shows a state before being arranged inside the outer cylinder 44 and forming a deformed portion 65 described later. The J-shaped holding portions 203 are scattered at four locations at equal intervals in the circumferential direction, and extend inward in the radial direction, gradually change direction, extend toward the tip side, and bend in a substantially J shape. The J-shaped holding portion 203 is configured to elastically deform and hold the urging metal 200 itself on the front end side 301 when the urging metal fitting 200 is attached to the front end side 301 of the separator 82. The holding strength can be adjusted by the width, shape, etc. of the J-type holding portion 203.

Further, the cylindrical portion extending portion 204 is formed between the J-shaped holding portion 203 is curved in a J-shape in the same manner as J-shaped holding portion 203 on the inside. However, the curvature is adjusted so that the J-shaped holding portion 203 protrudes radially inward from the cylindrical portion extending portion 204. As shown in FIG. 1, the deformed portion 205 is also formed in the tubular portion 201 as the deformed portion 65 that protrudes inward is formed in the second outer tubular portion 56 of the outer tube. The portion 201 urges the front end side surface of the flange portion 83 of the separator 82, and thus the separator 82 toward the rear end side.

  Next, the lead frame 10 will be described. A perspective view showing the appearance of the lead frame 10 is shown in FIG. Note that the air-fuel ratio sensor 2 of this embodiment has two types of lead frames 10 (the first lead frame 11 shown on the left side in FIG. 3 and the second lead frame 211 shown on the right side) having different frame locking portions. It is configured with. The lead frame 10 is formed of a well-known material (for example, Inconel, stainless steel, etc.) that can maintain elasticity (spring elasticity) even when repeatedly exposed to high temperatures.

  First, the first lead frame 11 includes a frame main body portion 12 made of a long plate-like member extending in the axial direction, and extends from the front end of the frame main body portion 12, and a part of the first lead frame 11 is part of the frame main body portion 12 and the sensor element. And an element abutting portion 16 that bends and extends so as to be arranged between the sensor element 4 and a part of the element abutting portion 16 abuts one of the electrode terminal portions of the sensor element 4. Has been.

  The frame main body portion 12 has a bending portion 13 at a substantially intermediate position in the axial direction, a front end side portion positioned at the front end of the bending portion 13 and a rear end side portion positioned at the rear end of the bending portion 13. Are configured so that the positions in the thickness direction of the plate surfaces are different.

  The first lead frame 11 includes a first frame locking portion 19 formed on the distal end side of the frame main body portion 12 so as to be disposed in the first locking groove 90 of the separator 82. The first frame locking portion 19 extends from the front end side surface of the frame main body portion 12 in a direction perpendicular to the plate surface, and is bent to have a portion parallel to the plate surface of the frame main body portion 12. Has been.

  The element contact portion 16 is connected to the distal end of the frame main body portion 12 and has a connecting side end portion 14 that is bent inward in the radial direction and changes its direction, while in the free state of the first lead frame 11 itself, The open side end 15 that is the rear end is formed so as to be separated from the frame main body 12. The element abutting portion 16 is curved in an arc shape so that the gap dimension from the axial intermediate portion to the frame main body portion 12 is longer than the gap dimension from the open side end portion 15 to the frame main body portion 12. The convex surface of the arcuate shape is in contact with the sensor element 4.

  The connection side end 14 of the element abutting portion 16 is configured to be elastically deformed when an external force is applied, and the connection side end 14 is elastically deformed so that the open side end 15 is the frame main body. 12, the open side end portion 15 is configured to come into contact with the curved portion 13 of the frame main body portion 12. The first lead frame is configured such that an arc-shaped portion of the element abutting portion 16 is elastically deformed when the open-side end portion 15 abuts on the curved portion 13 of the frame main body portion 12. Yes.

  Further, the first lead frame 11 is integrally provided with a lead wire connecting portion 17 formed wider than the frame main body portion 12 at the rear end portion (upper end portion in the drawing) of the frame main body portion 12. The lead wire connecting portion 17 is formed into a substantially cylindrical shape by bending, and then crimped radially inward with the core wire of the lead wire 46 (not shown) inserted thereinto. Connected to line 46.

  Next, the second lead frame 211 includes a second frame main body 212 having a width dimension at a tip side portion narrower than an intermediate position in the axial direction as compared with the frame main body 12 of the first lead frame 11, The second element abutting portion 216 is formed to be narrower than the element abutting portion 16 of one lead frame 11.

  The second frame body 212 has a plate surface width dimension different from that of the frame body 12 of the first lead frame 11, but the cross-sectional shape in a plane parallel to the axial direction and perpendicular to the plate surface is the frame body 12. The second curved portion 213 corresponding to the curved portion 13 is provided.

  The second element contact portion 216 is different in the width and thickness of the plate surface from the element contact portion 16 of the first lead frame 11, but the cross-sectional shape in a plane parallel to the axial direction and perpendicular to the plate surface is The second contact-side end 214 corresponding to the connection-side end 14 and the second open-side end 15 corresponding to the open-side end 15. 215.

  Further, the second lead frame 211 includes two second frame locking portions 219 formed on the distal end side of the second frame main body 212 so as to be disposed in the second locking groove 91 of the separator 82. Yes. The second frame locking portion 219 extends outward from the second frame main body portion 212 in a direction perpendicular to the plate surface and has a portion parallel to the plate surface of the second frame main body portion 212. It is configured to be bent. Further, the second lead frame 211 includes a second lead wire connecting portion 217 formed in a shape substantially the same as the lead wire connecting portion 17 of the first lead frame 11 at the rear end portion of the second frame main body portion 212. ing.

  In the lead frame 10 configured as described above, the four first lead frames 11 and the one second lead frame 211 are insulated from each other by the first rib portion 87 and the second rib portion 89. It is disposed in the insertion hole 84 of the separator 82. At this time, the four first lead frames 11 include two first frame arrangement grooves 86 corresponding to the electrode terminal portions 30 and 32 of the sensor element 4 and two second frames corresponding to the electrode terminal portions 34 and 36. Arranged in the arrangement groove 88, the second lead frame 211 is arranged in the first frame arrangement groove 86 corresponding to the electrode terminal portion 31 of the sensor element 4.

  A perspective view of the separator 82 in a state where the lead frame 10 is disposed in the insertion hole 84 is shown in FIG. As shown in FIG. 5, when the first lead frame 11 is disposed in the insertion hole 84, the first frame locking portion 19 of the first lead frame 11 is formed in the first locking groove 90 of the separator 82. Be placed. Further, when the second lead frame 211 is disposed in the insertion hole 84, the second frame locking portion 219 of the second lead frame 211 is disposed in the second locking groove portion 91 of the separator 82.

  The lead frame 10 is inserted into the insertion hole 84 of the separator 82 together with the lead wire 46 after the lead wire 46 is connected to the lead wire connection part 17 (second lead wire connection part 217). 84.

  Here, each lead frame 10 has the insertion hole 84 of the separator 82 in a state where the element contact portion 16 is elastically deformed while being in contact with any one of the electrode terminal portions 30, 31, 32, 24, 36 of the sensor element 4. It is clamped and fixed between the inner wall and the sensor element 4. In the air-fuel ratio sensor 2 of the present embodiment, as shown in FIG. 1, when viewed along the axial direction of the air-fuel ratio sensor 2 (vertical direction in FIG. 1), the element contact portion 16 of the lead frame 10 and the sensor The contact portion 301 with the electrode terminal portion of the element 4 is positioned behind the support portion 303 of the separator 82 by the urging metal fitting 200. In the present embodiment, the separator 82 is supported so that the support portion 303 of the separator 82 by the urging metal fitting 200 is located behind the contact portion 301 between the lead frame 10 and the electrode terminal portion of the sensor element 4. The formation position of the portion 83 is adjusted in advance.

  Next, an operation of assembling the air-fuel ratio sensor 2 while holding the separator 82 with the lead frame 10 assembled in the outer cylinder 44 will be described. In addition, although several methods are mentioned as an assembly method (manufacturing method) of the air-fuel ratio sensor 2, here, two methods are illustrated.

First, a method for assembling the first air-fuel ratio sensor 2 is as follows.
The five lead frames 10 to which the lead wires 46 are respectively connected are arranged inside the separator 82 as described above. At this time, the urging metal fitting 200 is attached so that the J-shaped holding portion 203 is in contact with the distal end side surface of the flange 83 against the outer periphery of the distal end side portion 301 of the separator 82. Next, the elastic seal member 50 is placed on the rear end surface 305 of the separator 82, and the outer cylinder 44 is moved from the elastic seal member 50 side in that state. The outer cylinder 44 is moved until the second step portion 48 of the outer cylinder 44 comes into contact with the protruding portion 305 of the elastic seal member 50, and the separator 82 and the elastic seal member 50 are accommodated in the outer cylinder 44. At this time, the separator 82 is accommodated in a non-contact state on the inner peripheral surface of the outer cylinder 44.

  Next, a portion of the second outer cylinder portion 56 of the outer cylinder 44 that is located on the radially outer side of the cylinder portion 201 of the urging metal fitting 200 is crimped radially inward using a pressing jig so that the deformable portion 65 is formed. The separator 82 is urged to the rear end side by the urging metal 200 by forming the urging metal 200 and also deforming it. In addition, the deformation | transformation part 65 was formed by Happo-maru caulking. Further, when the urging metal fitting 200 is deformed in a state where the separator 82 is in contact with the front end surface of the elastic seal member 50, the elastic seal member 55 is prevented from being displaced greatly from the rear end side. The urging metal fitting 200 was deformed in a state where a small load (about 5 N) was applied toward the distal end side.

Thereafter, a portion of the third outer cylinder portion 58 in the outer cylinder 44 that is positioned around the elastic seal member 50 is crimped using a crimping jig, and the elastic seal member is secured to the outer cylinder 44 and each lead wire 46 . 50 is hermetically sealed. As a result, the separator 82 is not in contact with the inner peripheral surface of the outer cylinder 44, and the urging metal 200 and the elastic seal member are in contact with the peripheral side of the rear end surface 305 abutting against the front end surface 52 of the elastic seal member 50. 50. In this way, an upper assembly is first prepared.

  Next, the assembly work of the lower assembly composed of the sensor element 4, the ceramic sleeve 6, the talc ring 108, the ceramic holder 106, the metal shell 102, the external protector 42, and the like is separately performed. In this lower assembly, the rear end portion of the plate-shaped sensor element 4 was appropriately manufactured so as to protrude from the rear end of the metal shell 102.

  Then, the upper assembly and the lower assembly thus manufactured are moved relative to each other, so that the sensor element 4 is inserted into the insertion hole 84 of the separator 82 in which the lead frame 10 is disposed inside. Insert the end side. Thereby, the element contact portion 16 (second element contact portion 216) of the lead frame 10 and the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4 come into contact with each other and are electrically connected to each other. It will be. Next, the outer cylinder 44 (first outer cylinder portion 54) disposed on the outer side in the radial direction of the metal shell 102 is caulked inward in the radial direction and laser welding is performed on the entire circumference, thereby joining the metal shell 102 and the outer cylinder 44 together. Do. In this way, the air-fuel ratio sensor 2 is completed.

Next, as a method for assembling the air-fuel ratio sensor 2, a second method will be described.
The five lead frames 10 to which the lead wires 46 are respectively connected are arranged inside the separator 82 as described above. At this time, the urging metal fitting 200 is attached so that the J-shaped holding portion 203 is in contact with the distal end side surface of the flange 83 against the outer periphery of the distal end side portion 301 of the separator 82. Next, the elastic seal member 50 is placed on the rear end surface 305 of the separator 82, and the outer cylinder 44 is moved from the elastic seal member 50 side in that state. The outer cylinder 44 is moved until the second step portion 48 of the outer cylinder 44 abuts against the protruding portion 53 of the elastic seal member 50, and the separator 82 and the elastic seal member 50 are accommodated in the outer cylinder 44. At this time, the separator 82 is accommodated in a non-contact state on the inner peripheral surface of the outer cylinder 44.

Next, a portion of the second outer cylinder portion 56 of the outer cylinder 44 that is located on the radially outer side of the cylinder portion 201 of the urging metal fitting 200 is crimped radially inward using a pressing jig so that the deformable portion 65 is formed. The separator 82 is urged to the rear end side by the urging metal 200 by forming the urging metal 200 and also deforming it. In this way, an upper assembly is first prepared. In addition, the deformation | transformation part 65 was formed by Happo-maru caulking. Further, in deforming the urging metal fitting 200 a separator 82 in a state in contact with the front end surface of the elastic seal member 50, so that the position deviation of the elastic seal member 50 does not occur significantly, from the rear end side of the elastic seal member 50 The urging metal fitting 200 was deformed in a state where a small load (about 5 N) was applied toward the distal end side.

  Next, the assembly work of the lower assembly composed of the sensor element 4, the ceramic sleeve 6, the talc ring 108, the ceramic holder 106, the metal shell 102, the external protector 42, and the like is separately performed. In this lower assembly, the rear end portion of the plate-shaped sensor element 4 was appropriately manufactured so as to protrude from the rear end of the metal shell 102.

  Then, the upper assembly and the lower assembly thus manufactured are moved relative to each other, so that the sensor element 4 is inserted into the insertion hole 84 of the separator 82 in which the lead frame 10 is disposed inside. Insert the end side. Thereby, the element contact portion 16 (second element contact portion 216) of the lead frame 10 and the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4 come into contact with each other and are electrically connected to each other. It will be.

  Here, in the second assembling method, the separator 82 of the upper assembly is urged toward the elastic seal member 50 as the urging metal fitting 200 is deformed. Unlike the eye assembly method, the elastic seal member 50 is not compressed and deformed by caulking the outer cylinder 44. For this reason, the clamping force of the separator 82 clamped between the urging metal fitting 200 and the elastic seal member 50 is relatively small. By the way, the sensor element 4 constituting the lower assembly is assembled slightly eccentric with respect to the central axis of the metal shell 102 due to dimensional tolerances of the ceramic sleeve 6, the metal shell 102, and the like and factors in manufacturing the sensor element 4 itself. Or the back end protruding from the metal shell 102 may be warped.

  However, in the upper assembly in the second assembling method, as described above, the separator 82 disposed between the urging metal fitting 200 and the elastic seal member 50 is clamped by a relatively small clamping force. Therefore, when the rear end side of the sensor element 4 is inserted into the insertion hole 84 of the separator 82, even if the rear end portion of the sensor element 4 is warped, the supporting portion of the separator 82 by the urging metal fitting 200 is a fulcrum. Thus, since the separator 82 is allowed to tilt slightly, it is possible to effectively prevent the sensor element 4 from being cracked or broken.

Next, the outer cylinder 44 (first outer cylinder portion 54) disposed on the outer side in the radial direction of the metal shell 102 is caulked inward in the radial direction and laser welding is performed on the entire circumference, thereby joining the metal shell 102 and the outer cylinder 44 together. Do. Thereafter, a portion of the third outer cylinder portion 58 in the outer cylinder 44 that is positioned around the elastic seal member 50 is crimped using a crimping jig, and the elastic seal member is secured to the outer cylinder 44 and each lead wire 46 . 50 is hermetically sealed. As a result, the separator 82 is not in contact with the inner peripheral surface of the outer cylinder 44, and the urging metal 200 and the elastic seal member are in contact with the peripheral side of the rear end surface 305 abutting against the front end surface 52 of the elastic seal member 50. 50 is finally clamped with a large clamping force. In this way, the air-fuel ratio sensor 2 is completed.

  In the present embodiment, the lead frame 10 corresponds to the electrode lead terminal described in the claims, and the urging metal fitting 200 corresponds to the urging member.

  As described above, in the air-fuel ratio sensor 2 of the present embodiment, the separator 82 is held in the outer cylinder 44 with its outer peripheral surface not in contact with the inner peripheral surface of the outer cylinder 44. That is, the separator 82 is accommodated in the outer cylinder 44 with a gap between the separator 82 and the inner peripheral surface of the outer cylinder 44. Thereby, even when a stepping stone or the like collides with the outer cylinder 44, the compressive stress due to the impact can be released by the gap. Therefore, even if an impact is applied from the outside of the outer cylinder 44, the impact is not directly transmitted to the separator 82, and the breakage of the separator 82 can be suppressed.

  Further, in the present embodiment, when the separator 82 is held in the outer cylinder 44 in a non-contact state with respect to the inner peripheral surface of the outer cylinder 44, It is held in a state of being biased to the end side. As described above, the separator 82 is brought into contact with the elastic seal member 50 to be elastically held, so that even if an external impact is applied to the outer cylinder 44, the elastic seal member 50 reduces or absorbs the impact. It is possible to prevent the 82 from swinging in the outer cylinder 44. Therefore, the separator 82 can be stably held in the outer cylinder 44 when the air-fuel ratio sensor 2 is used while the separator 82 is held in a non-contact state with respect to the inner peripheral surface of the outer cylinder 44.

  Furthermore, in this embodiment, since the separator 82 is held in the outer cylinder 44 using the biasing member 200 shown in FIG. 6, the separator 82 can be held stably.

Further, in the present embodiment, the support portion 301 of the separator 82 by the urging metal fitting 200 is more air-fuel ratio sensor 2 than the contact portion 303 between the element contact portion 16 of the lead frame 10 and the electrode terminal portion of the sensor element 4. It is located on the rear side when viewed along the axial direction. As described above, the support portion 301 of the separator 82 by the urging metal fitting 200 and the contact portion 303 between the element contact portion 16 of the lead frame 10 and the electrode terminal portion of the sensor element 4 are arranged in the axial direction of the air-fuel ratio sensor 2. If the separator 82 is swung with the support portion 301 as a fulcrum, the stress due to the swinging of the separator 82 does not easily reach the contact portion 303. Generation | occurrence | production of the bending etc. of the element 4 can be suppressed effectively.

  Furthermore, in the present embodiment, the outer peripheral surface of the separator 82 and the inner peripheral surface of the outer cylinder 44 are separated by 0.5 mm or more when viewed in the radial direction. Even when 44 itself deforms, it is difficult for the inner peripheral surface of the outer cylinder 44 to touch the outer peripheral surface of the separator 82, and it is possible to effectively prevent the separator 82 from being damaged.

  Further, in the present embodiment, the rear end surface 305 of the separator 82 is formed in a shape that is recessed in a spherical shape from the peripheral edge toward the insertion hole 84 located in the center, and only the peripheral side of the rear end surface 305 of the separator 82 is elastic. It is made to contact the front end surface 52 of the seal member 50. With this configuration, even when the elastic seal member 50 undergoes thermal expansion when the air-fuel ratio sensor 2 is used, the elastic seal member 50 can escape to a recessed portion of the rear end surface 305 of the separator 82. . Therefore, even when the elastic seal member 50 undergoes thermal expansion, it is possible to suppress a problem that the separator 82 is restrained (compressed) and damaged.

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. . For example, the sensor to which the present invention is applied is not limited to a gas sensor having a sensor element in which the number of electrode terminal portions formed is five, but includes a sensor element having four or fewer electrodes or six or more electrodes. It can also be applied to a configured gas sensor. Further, in the above-described embodiment, a sensor element is used in which an element part for performing gas detection and a heater for heating the element part are joined via a ceramic layer. A sensor element that is integrally fired in a state in which the part and the heater are laminated may be used.

It is sectional drawing which shows the whole area | region air-fuel-ratio sensor of embodiment. It is a perspective view showing the schematic structure of the sensor element which comprises a whole area | region air fuel ratio sensor. It is a perspective view showing the appearance of a lead frame. It is a perspective view showing the external appearance of a separator. It is a perspective view of a separator in the state where a lead frame is arranged in an insertion hole. It is a partial fracture side view of the energizing metal fitting arranged on the perimeter of the tip side part of a separator.

Explanation of symbols

2 ... All-range air-fuel ratio sensor (gas sensor), 4 ... Sensor element, 6 ... Ceramic sleeve, 8 ... Detection part, 10 ... Lead frame (electrode extraction terminal), 11 ... First lead frame 30, 31, 32, 34, 36 ... electrode terminal portion, 44 ... outer cylinder, 50 ... elastic seal member, 54 ... first outer cylinder portion, 56 ... 2nd outer cylinder part, 58 ... 3rd outer cylinder part, 61 ... Lead wire insertion hole, 64 ... Lead wire, 65 ... Deformation part, 82 ... Separator, 83 ... 鍔, 84... Insertion hole, 86... First frame arrangement groove, 88... Second frame arrangement groove, 102. ... Second lead frame.

Claims (5)

A sensor element that extends in the axial direction and is exposed to the gas to be measured on the tip side;
A metal shell for holding the sensor element;
An outer cylinder connected to the metal shell at its tip,
A plurality of electrode extraction terminals electrically connected to the sensor element;
A plurality of lead wires electrically connected to each of the electrode lead terminals;
A separator that is housed inside the outer cylinder and that each of the electrode lead-out terminals is located within itself and insulates between the electrode lead-out terminals,
An elastic seal member which has a lead wire insertion hole through which each of the lead wires is inserted, and is arranged on the rear side of the separator in the outer cylinder;
A gas sensor comprising:
The separator is held in the outer cylinder while being urged toward the rear end side while being in contact with the front end surface of the elastic seal member without contacting the outer peripheral surface of the separator with the inner peripheral surface of the outer cylinder. Has been
The separator is located between the rear end side portion located on the rear end side, the front end side portion located on the front end side, and between the rear end side portion and the front end side portion. And a flange portion including a distal end side surface facing the distal end side between the distal end side portion and a pressing force from the distal end side surface of the flange portion toward the distal end surface of the elastic seal member. The gas sensor is urged toward the rear end side in contact with the front end surface of the elastic seal member by an urging member, and is sandwiched between the elastic seal member and the urging member. . The gas sensor according to claim 1,
The urging member is disposed on the outer periphery of the front end side portion of the separator, and a portion of the outer cylinder that is located on the radially outer side of the urging member is pressed radially inward to protrude inward. A gas sensor that is deformed so as to urge the separator toward the rear end side by a deformed portion that has been deformed. The gas sensor according to claim 1 or 2, wherein
The sensor element has a plate shape and a plurality of electrode terminal portions on the front and back surfaces on the rear end side,
The electrode lead-out terminal is sandwiched and fixed between the separator and the sensor element in a state of being in contact with any one of the electrode terminal portions of the sensor element,
A gas sensor in which a contact portion between the electrode lead-out terminal and the electrode terminal portion of the sensor element and a support portion of the separator by the biasing member are shifted when viewed along the axial direction of the gas sensor. . It is a gas sensor given in any 1 paragraph of Claims 1-3,
The gas sensor in which the outer peripheral surface of the separator and the inner peripheral surface of the outer cylinder are separated by 0.5 mm or more when viewed in the radial direction. The gas sensor according to any one of claims 1 to 4,
A rear end surface of the separator is formed in a shape that is recessed radially inward from a peripheral edge, and the separator is formed on the outer cylinder such that a peripheral side of the rear end surface is in contact with a front end surface of the elastic seal member. Gas sensor being held.