Gas sensor

Abstract

Provided is a gas sensor in which breakage of a terminal fitting at the rear end side of a separator is suppressed. A gas sensor (10) is provided with: a plate-shaped sensor element (20) extending in the direction of an axis (O) and having electrode pads (21a, 21b) on main surfaces (20m1, 20m) on the rear end side; a terminal fitting (71) extending in the axial direction and electrically connected to the electrode pad; and a spacer (50) having a housing portion (50h) penetrating in the axial direction and housing the rear end side of the sensor element and the terminal fitting, the spacer holding the terminal fitting, the housing portion having a tapered surface (50s) that expands in diameter in a direction perpendicular to the main surface as the housing portion approaches a surface facing the rear end of the spacer, the terminal fitting having a protruding portion (75) protruding toward the tapered surface, the protruding portion being in contact with the tapered surface.

Description

Technical Field

[0001] The present invention relates to a gas sensor suitable for detecting the gas concentration of a specific gas contained in combustion gas or exhaust gas of, for example, a burner or an internal combustion engine. Background Art

[0002] As a detector for detecting oxygen or NO in exhaust gas of automobiles, etc. x As a gas sensor for measuring the concentration of a gas, a gas sensor having a plate-shaped sensor element using a solid electrolyte is known.

[0003] As such a gas sensor, a gas sensor is used in which a plurality of electrode pads are provided on the rear end side of the opposing main surfaces of a plate-shaped sensor element, and terminal fittings are electrically contacted with the electrode pads to extract a sensor output signal from the sensor element to the outside (Patent Document 1).

[0004] In the gas sensor of Patent Document 1, each terminal fitting is held in a two-part insulating connector (spacer). The connector houses each terminal fitting in a box-shaped housing of the same shape, and the housings are coupled and fixed with a metal clamp. When the rear end side of the sensor element is inserted into the insertion hole of the connector, the terminal fitting inside the connector is in electrical contact with the electrode pad.

[0005] On the other hand, at the rear end side of the connector, the insertion hole faces the surface toward the rear end and expands radially outward in a direction perpendicular to the main surface of the sensor element, thereby suppressing interference between the terminal fittings led to the rear end side of the connector and the inner surface of the connector.

[0006] Prior art literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-209104 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, it has been found that when the rear end of the connector is enlarged, the distance between the terminal fitting and the connector increases, and the terminal fitting is easily vibrated and broken in the connector due to vibrations during use of the gas sensor.

[0010] Therefore, an object of the present invention is to provide a gas sensor in which breakage of a terminal fitting at the rear end side of a separator is suppressed.

[0011] Means for solving problems

[0012] In order to solve the above problems, the gas sensor of the present invention includes: a plate-shaped sensor element that extends along the axial direction and has an electrode pad on the main surface on the rear end side; a terminal fitting that extends along the above-mentioned axial direction and is electrically connected to the above-mentioned electrode pad; and a spacer that has a receiving portion that penetrates in the above-mentioned axial direction and houses the rear end side of the above-mentioned sensor element and the above-mentioned terminal fitting, and the above-mentioned spacer holds the above-mentioned terminal fitting. The gas sensor is characterized in that the above-mentioned receiving portion has a conical surface that expands in a direction perpendicular to the above-mentioned main surface as it approaches the rear end surface of the above-mentioned spacer, the above-mentioned terminal fitting has a protrusion that protrudes toward the above-mentioned conical surface, and the above-mentioned protrusion abuts against the above-mentioned conical surface.

[0013] The terminal fitting is plate-shaped, and the plate surface faces the main surface of the sensor element. Therefore, due to vibrations during the use of the gas sensor, etc., the plate-shaped terminal fitting is likely to vibrate and break in a direction perpendicular to the main surface.

[0014] Therefore, a protrusion that protrudes toward the conical surface of the spacer is provided on the terminal fitting, and the protrusion abuts against the conical surface. As a result, the terminal fitting is fixed to the spacer via the conical surface, so that the vibration of the terminal fitting can be suppressed and the breakage of the terminal fitting can be suppressed.

[0015] In the gas sensor of the present invention, the above-mentioned protrusion may also be a tongue piece portion that extends toward the front end side in the above-mentioned axial direction.

[0016] In this way, if the protrusion becomes a tongue piece portion that extends toward the front end side in the axial direction, the tip (free end) of the protrusion easily abuts against the conical surface at an angle, and the front end of the protrusion becomes flat and easily catches on the conical surface. As a result, the terminal fitting is more reliably fixed to the spacer via the conical surface.

[0017] In the gas sensor of the present invention, it may also be that the above-mentioned terminal fitting is plate-shaped, the plate surface faces the above-mentioned conical surface, and the above-mentioned protrusion is a plate piece portion that folds back from at least one side surface of the above-mentioned terminal fitting toward the above-mentioned conical surface.

[0018] According to this gas sensor, the protrusion can be easily formed only by folding back the side surface of the plate-shaped terminal fitting.

[0019] In the gas sensor of the present invention, it may also be that the above-mentioned protrusion is a bent portion formed by bending the above-mentioned terminal fitting so as to protrude toward the above-mentioned conical surface.

[0020] According to this gas sensor, the protrusion can be easily formed only by bending the terminal fitting toward the conical surface.

[0021] In the gas sensor of the present invention, it may also be that the above-mentioned protrusion is formed by fixing another component to the portion of the above-mentioned terminal fitting facing the above-mentioned conical surface.

[0022] According to this gas sensor, a protrusion can be easily formed only by other components of the fixed terminal fitting.

[0023] Advantages of the Invention

[0024] According to the present invention, a gas sensor can be obtained in which breakage of the terminal fitting at the rear end side of the spacer is suppressed. Description of the Drawings

[0025] Figure 1 is a cross-sectional view of the gas sensor according to an embodiment of the present invention.

[0026] Figure 2 is a perspective view of the spacer.

[0027] Figure 3 is along Figure 2 a cross-sectional view taken along line A-A.

[0028] Figure 4 is a perspective view of the connection terminal.

[0029] Figure 5 is a perspective view of the connection terminal in which the protrusion is a plate portion.

[0030] Figure 6 is a perspective view of the connection terminal in which the protrusion is a bent portion.

[0031] Figure 7 is a perspective view of the connection terminal in which the protrusion is other components. Detailed Description of the Invention

[0032] Hereinafter, embodiments of the present invention will be described together with Figure 1 the accompanying drawings.

[0033] Figure 1 is a cross-sectional view of the gas sensor (sensor) 10 according to an embodiment of the present invention along the axis O direction, Figure 2 is a perspective view of the spacer 50, Figure 3 is along Figure 2 a cross-sectional view taken along line A-A, Figure 4 is a perspective view of the connection terminal 71.

[0034] As Figure 1 shown, the gas sensor 10 includes: a sensor element 20 that measures a specific gas component in the gas to be measured; a protector 30 that protects the front end portion of the sensor element 20; and a sensor assembly 40 that includes a spacer 50 that houses the rear end side of the sensor element 20. The gas sensor 10 is installed, for example, in the exhaust pipe of a vehicle and is used to measure gas components such as NOx, O 2 and the like in the gas to be measured (exhaust gas).

[0035] The sensor element 20 is an elongated strip-shaped plate element extending along the direction of axis O, and is formed by laminating ceramic substrates and the like composed of oxygen ion conductive solid electrolyte layers such as zirconia (ZrO 2 ). In addition, the end of the sensor element 20 on the protector 30 side is referred to as the front end, and the end on the spacer 50 side is referred to as the rear end.

[0036] On the main surfaces 20m1, 20m2 ( Figure 2 , Figure 3 ) on the rear end side of the sensor element 20, a plurality of electrode pads 21a, 21b ( Figure 3 ) are formed.

[0037] Specifically, as Figure 3 shown, on one main surface 20m1 of the sensor element 20, a plurality of electrode pads 21a are arranged separately in the width direction of the sensor element 20. Similarly, on the other main surface 20m2 of the sensor element 20, a plurality of electrode pads 21b are arranged separately in the width direction of the sensor element 20.

[0038] In addition, the plurality of electrode pads may be arranged only on one main surface 20m1 or 20m2 of the sensor element 20.

[0039] The electrode pads 21a, 21b are used to apply a voltage to the sensor element 20, or output a detection signal of the sensor element 20, or supply power to a heater in the case where the sensor element 20 has a heater.

[0040] As Figure 1 shown, the protector 30 is arranged so as to surround the periphery of the front end of the sensor element 20. The protector 30 includes an inner protector 31 covering the front end of the sensor element 20 and an outer protector 32 covering the inner protector 31. The inner protector 31 is formed in a cylindrical shape and has an inner gas introduction hole 31a for introducing the gas to be measured at the front end of the sensor element 20. The outer protector 32 is formed in a bottomed cylindrical shape and has an outer gas introduction hole 32a for introducing the gas to be measured on the side surface. The inner protector 31 and the outer protector 32 are made of a metal such as SUS, for example.

[0041] The sensor assembly 40 includes: a metal main body fitting 41, a cylindrical inner cylinder 42 and an outer cylinder 46 welded and fixed to the main body fitting 41, and a spacer 50 connected to the rear end of the sensor element 20.

[0042] The main body fitting 41 is mounted on, for example, an exhaust pipe of a vehicle through the external threaded portion 41a. A plurality of ceramic sleeves 43a to 43c and powder filling layers 44a and 44b such as talc filled between the ceramic sleeves 43a and 43b and between the ceramic sleeves 43b and 43c are sealed inside the inner tube 42, and they are clamped and sealed by the metal ring 45 and the inner wall of the main body fitting 41.

[0043] The outer cylinder 46 covers the inner cylinder 42, the sensor element 20, and the spacer 50. In addition, the rubber gasket 47 closes the opening on the rear end side of the outer cylinder 46. Figure 4 ) A lead wire 48 is connected by crimping or the like, and the lead wire 48 passes through a gasket hole 47a that penetrates the gasket 47 in the direction of the axis O and is led out from the rear end of the gasket 47 to the outside.

[0044] Furthermore, the connection portion 71 g of the terminal fitting 71 and the lead wire 48 are inserted through the gasket hole 47 a .

[0045] Next, the spacer 50 will be described. Figure 2 As shown, the spacer 50 includes a first member 51 a and a second member 51 b made of ceramic such as alumina sintered body, and a metal clamp 90 for sandwiching and fixing the first member 51 a and the second member 51 b.

[0046] Furthermore, the terminal fittings 71 are held by the first member 51 a or the second member 51 b , and are arranged so as to face and contact the electrode pads 21 a and 21 b of the sensor element 20 in a one-to-one manner.

[0047] The first component 51a and the second component 51b respectively arrange and hold four terminal fittings 71 in the width direction perpendicular to the length direction (=axis O direction) of the terminal fittings 71. The first component 51a and the second component 51b have the same box-shaped shape, so the same components are marked with the same reference numerals for description. In addition, the first component 51a and the second component 51b are collectively described as the housing 51.

[0048] The housing 51 includes: a storage portion 50h that passes through the direction of the axis O, four locking grooves 52 that lock the front end side of the terminal fitting 71, four insertion holes 53 for inserting the upright portion 71d of the central portion of the terminal fitting 71, and a locking portion 54 formed in each insertion hole 53 and locking the terminal fitting 71.

[0049] The housing 51 includes a convex portion 55 on one side in the width direction across the sensor element 20, and includes limiting members 56 and 57 on the other side that limit the distance between the first member 51a and the second member 51b in the thickness direction (see FIG. Figure 2). The convex portion 55 is inserted into the recess between the restricting members 56 and 57 of the opposing housing 51, thereby restricting the relative position in the thickness direction between the first member 51a and the second member 51b.

[0050] As Figure 4 shown, the terminal fitting 71 is a metal member held by the housing 51 at a position facing the electrode pads 21a, 21b of the sensor element 20 one-to-one, and includes: a front end portion 71a that is engaged with the engaging groove 52 by a bent shape; a protruding portion 71b that protrudes bent toward the sensor element 20; a contact portion 71c that contacts the electrode pads 21a, 21b by protruding bent toward the sensor element 20; a standing portion 71d that is inserted into the insertion hole 53; a bent portion 71f that is led out to the outside of the spacer 50; and a connection portion 71g that crimps and holds a plurality of core wires 48a of the lead wire 48 outside the spacer 50.

[0051] In addition, a part of the bent portion 71f has a protruding portion 75 that is cut and protrudes toward the side opposite to the sensor element 20, which will be described in detail later.

[0052] The protruding portion 71b and the contact portion 71c are arranged along the length direction of the terminal fitting 71, and the contact portion 71c is arranged at a position closer to the connection portion 71g than the protruding portion 71b. Both the protruding portion 71b and the contact portion 71c are formed so as to be elastically deformable. The standing portion 71d includes a locking portion 71e that is locked to the locking portion 54 by a bent shape.

[0053] In addition, the contact portion 71c of the terminal fitting 71 held by the first member 51a faces and contacts the electrode pad 21a of the sensor element 20 one-to-one, and the contact portion 71c of the terminal fitting 71 held by the second member 51b faces and contacts the electrode 21b of the sensor element 20 one-to-one ( Figure 3 ).

[0054] On the other hand, as Figure 3 shown, the electrode pads 21a, 21b are formed from the rear end of the sensor element 20 to a position between the contact portion 71c and the protruding portion 71b.

[0055] As Figure 2 shown, the clamp 90 is formed by bending a plate-like metal and has an elastic force capable of clamping the first member 51a and the second member 51b and pressing them in the direction of approaching each other. When the first member 51a and the second member 51b are clamped by this elastic force, the restricting members 56, 57 of the first member 51a contact the second member 51b, and the restricting members 56, 57 of the second member 51b contact the first member 51a. Thereby, the distance between the first member 51a and the second member 51b is fixed.

[0056] In addition, in a state where the sensor element 20 and the terminal fitting 71 are clamped by the first member 51a and the second member 51b in such a manner that the contact portion 71c of the terminal fitting 71 faces the electrode pads 21a and 21b of the sensor element 20, when the clamping member 90 clamps the first member 51a and the second member 51b, the protruding portion 71b and the contact portion 71c are elastically deformed by the pressing force from the clamping member 90, and the sensor element 20 is clamped and fixed.

[0057] At this time, the protruding portion 71b and the contact portion 71c are elastically deformed and pressed, whereby the sensor element 20 can be reliably clamped and fixed. In addition, since the contact portion 71c is elastically deformed, the electrical contact between the contact portion 71c and the electrode pads 21a and 21b can be more reliably maintained.

[0058] Next, the characteristic parts of the present invention will be described.

[0059] First, as Figure 3 shown, the spacer 50 has a housing portion 50h that penetrates in the direction of the axis O, and the housing portion 50h houses the rear end side of the sensor element 20 and the terminal fitting 71.

[0060] More specifically, the housing portion 50h forms an opening in a rectangular shape that is slightly larger than the outer shape of the sensor element 20 on the front end face of the housing 51, and communicates with each insertion hole 53 on the rear end side thereof. The housing portion 50h may also be an insertion through hole that is only open at the front end and the rear end of the housing 51.

[0061] In addition, in this example, the housing portion 50h is formed by respectively recessing a part of the facing surfaces of the first member 51a and the second member 51b.

[0062] Moreover, the housing portion 50h has a tapered surface 50s that expands in a direction perpendicular to the two main surfaces 20m1 and 20m2 of the sensor element 20 as it approaches the rear end-facing surface of the spacer 50 ( Figure 3 the up and down direction).

[0063] In addition, "in a direction perpendicular to the main surfaces 20m1 and 20m2" means that as long as it has a direction component perpendicular to the main surfaces 20m1 and 20m2, it also includes cases where the degree of expansion of the tapered surface 50s varies according to the position. For example, it also includes cases where the tapered surface 50s is not parallel to the main surfaces 20m1 and 20m2, cases where the tapered surface 50s is a curved surface, cases where the tapered surface 50s itself is parallel to the main surfaces 20m1 and 20m2 but the front edge and the rear edge of the tapered surface 50s are not parallel to the main surfaces 20m1 and 20m2 (cases where the lengths and positions of the line segments when the tapered surface 50s is cut along the main surfaces 20m1 and 20m2 are different), etc.

[0064] On the other hand, in this example, the terminal fitting 71 is plate-shaped, and the plate surface faces the main surfaces 20m1 and 20m2 of the sensor element 20. The plate-shaped terminal fitting 71 vibrates in a direction perpendicular to the plate surface. Therefore, due to vibrations during the use of the gas sensor 10 or the like, the terminal fitting 71 is likely to vibrate and break in a direction perpendicular to the main surfaces 20m1 and 20m2 ( Figure 3 the V direction in

[0065] ). Therefore, as described above, a protrusion 75 protruding toward the conical surface 50s (the side opposite to the sensor element 20) is provided on the terminal fitting 71, and the protrusion 75 is brought into contact with the conical surface 50s.

[0066] Thereby, the terminal fitting 71 is fixed to the spacer 50 via the conical surface 50s, so that vibration of the terminal fitting 71 can be suppressed and breakage of the terminal fitting 71 can be suppressed.

[0067] In addition, as Figure 4 shown, in this example, the central portion in the width direction on the front end side of the bent portion 71f is cut up so that the front end side becomes a free end to form the protrusion 75. In addition, the protrusion 75 has a substantially rectangular shape and is a tongue portion extending toward the front end side in the direction of the axis O.

[0068] In this way, if the protrusion 75 is a tongue portion extending toward the front end side in the direction of the axis O, the tip (free end) of the protrusion 75 easily comes into contact with the conical surface 50s at an angle, and the front end of the protrusion 75 becomes flat and easily catches on the conical surface 50s. As a result, the terminal fitting 71 is more reliably fixed to the spacer 50 via the conical surface 50s.

[0069] On the contrary, if the protrusion 75 extends toward the rear end side in the direction of the axis O (that is, the rear end side of the protrusion 75 is the free end), the tip (free end) of the protrusion 75 becomes an angle close to being parallel to the conical surface 50s that expands toward the rear end side, and it may be difficult to come into contact with the conical surface 50s, or the catching state with the conical surface 50s may easily become disengaged.

[0070] In addition, the protrusion 75 may extend obliquely with respect to the conical surface 50s instead of being parallel to the conical surface 50s.

[0071] The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and equivalents included in the spirit and scope of the present invention are involved.

[0072] The shape, position, and number of protrusions provided on one terminal are not limited.

[0073] For example, as Figure 5 shown, it may also be that the plate surface 71s of the terminal fitting 71 faces the conical surface 50s, and the protrusion 75B is a plate piece portion that folds back from at least one side surface of the terminal fitting 71 toward the conical surface 50s.

[0074] In addition, in the example of Figure 5 the projecting portion 75B becomes a pair of members that are folded back from both side surfaces of the terminal fitting 71 at the same position in the direction of the axis O.

[0075] In addition, for example, as shown in Figure 6 the projecting portion 75C can also be a bent portion formed by bending the terminal fitting 71 so as to project toward the conical surface 50s.

[0076] In addition, in the example of Figure 6 the projecting portion 75C is shaped to be convex toward the conical surface 50s, but for example, it can also be shaped to be bent at an acute angle (in a "<" shape) toward the conical surface 50s.

[0077] In addition, for example, as shown in Figure 7 the projecting portion 75D can also fix other components at the portion facing the conical surface 50s of the terminal fitting 71.

[0078] For example, in the example of Figure 7 the projecting portion 75D is in the shape of a pin in which the tip of a round bar of metal such as stainless steel becomes a small-diameter portion 75p, and the pin (projecting portion) 75D is tightly fitted into the mounting hole 71h opened in the plate surface facing the conical surface of the terminal fitting 71 for fixation.

[0079] In addition, in the example of Figures 5 - 7 near the projecting portions 75B to 75D, the terminal fitting 71 extends straight and no bent portion 71f is provided.

[0080] The terminal fitting is not limited to a plate shape and can also be a rod shape. In addition, for example, a plate-shaped projecting portion can be mounted like a flag at the portion facing the conical surface of the rod-shaped terminal fitting.

[0081] The separator 50 is not limited to a box shape divided into two parts and can also be a cylindrical shape such as a cylinder.

[0082] Description of Reference Numerals

[0083] 10 Gas sensor

[0084] 20 Sensor element

[0085] 20m1 and 20m2 Main surfaces of the sensor element

[0086] 21a, 21b Electrode pads

[0087] 50 Separator

[0088] 50h Receiving portion

[0089] 50s Conical surface

[0090] 71 Terminal fitting

[0091] 75 projection

[0092] 75B projection (plate part)

[0093] 75C projection (bending part)

[0094] 75D projection (other components)

[0095] Axis O.

Claims

1. A gas sensor comprising: A plate-shaped sensor element extending in the axial direction and having an electrode pad on a main surface on the rear end side; a terminal fitting extending along the axial direction and electrically connected to the electrode pad; and A spacer having a housing portion that penetrates through the sensor element in the axial direction and houses the rear end side of the sensor element and the terminal fitting, wherein the spacer holds the terminal fitting. The gas sensor is characterized in that The receiving portion has a tapered surface that increases in diameter in a direction perpendicular to the main surface as it approaches a surface of the spacer that faces the rear end. The terminal fitting has a protrusion protruding toward the tapered surface, The protrusion abuts against the tapered surface.

2. The gas sensor according to claim 1, characterized in that The protrusion is a tongue portion extending toward the front end side in the axial direction.

3. The gas sensor according to claim 1, characterized in that: The terminal fitting is in a plate shape, with the plate surface facing the conical surface, The protrusion is a plate portion folded back from at least one side surface of the terminal fitting toward the tapered surface.

4. The gas sensor according to claim 1, characterized in that: The protrusion is a bent portion formed by bending the terminal fitting so as to protrude toward the tapered surface.

5. The gas sensor according to claim 1, characterized in that: The protrusion is formed by fixing another member to a portion of the terminal fitting facing the tapered surface.

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