Gas sensor

Abstract

The present invention provides a gas sensor in which breakage of a terminal fitting on the rear end side of a separator is suppressed. A gas sensor (10) is provided with: a plate-shaped sensor element (20) that extends in the direction of an axis (O) and has electrode pads (21a, 21b) on main surfaces (20m1, 20m2) on the rear end side; a terminal fitting (71) that extends in the axial direction and is electrically connected to the electrode pad; and a spacer (50) that holds the terminal fitting and that has a housing section (50h) that penetrates in the axial direction and houses the rear end side of the sensor element and the terminal fitting, in which the housing section has a tapered surface (50s) that expands in diameter in a direction perpendicular to the main surface as the housing section faces the rear end of the spacer. The rear end of the sensor element is disposed on the inside of the tapered surface in the axial direction.

Description

Technical Field

[0001] The present invention relates to a gas sensor suitable for detecting the gas concentration of specific gases contained in combustion gases and exhaust gases of, for example, burners and internal combustion engines. Background Art

[0002] As a gas sensor for detecting the concentration of oxygen and NO in the exhaust gas of automobiles and the like x A gas sensor using a plate-shaped sensor element made of a solid electrolyte is known.

[0003] As such a gas sensor, the following gas sensor is used: a plurality of electrode pads are provided on the rear end side of the opposite main surfaces of the plate-shaped sensor element, and terminal metal members are brought into electrical contact with the electrode pads respectively, and the sensor output signal from the sensor element is output to the outside (Patent Document 1).

[0004] In addition, in the gas sensor of Patent Document 1, each terminal metal member is held by a two-part insulating connector (separator). The connector houses each terminal metal member in a box-shaped housing of the same shape, combines the housings, and fixes them with a metal clamp. Then, when the rear end side of the sensor element is inserted into the through hole of the connector, the terminal metal member inside the connector is in electrical contact with the electrode pad.

[0005] On the other hand, on the rear end side of the connector, the through hole faces the rear end facing surface and expands in diameter radially outward in a direction perpendicular to the main surface of the sensor element. Thereby, interference between the terminal metal member led out to the rear end side of the connector and the inner surface of the connector is suppressed.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-209104 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, it has been clarified that if the rear end side of the connector is expanded in diameter, the interval between the terminal metal member and the connector becomes large, and the terminal metal member vibrates and swings in the connector due to vibrations during the use of the gas sensor and is liable to break.

[0011] Therefore, an object of the present invention is to provide a gas sensor that suppresses breakage of the terminal metal member on the rear end side of the separator.

[0012] Solutions to the Problems

[0013] In order to solve the above problems, the gas sensor of the present invention includes: a sensor element which is plate-shaped, extends along an axis direction, and has an electrode pad on a main surface at a rear end side; a terminal metal member which extends along the axis direction and is electrically connected to the electrode pad; and a separator which has a receiving portion that penetrates in the axis direction, the receiving portion receiving the rear end side of the sensor element and the terminal metal member, the separator holding the terminal metal member, and is characterized in that the receiving portion has a tapered surface that expands in a direction perpendicular to the main surface as it approaches a rear end facing surface of the separator, and the rear end of the sensor element is arranged inside the tapered surface along the axis direction.

[0014] According to this gas sensor, the plate surface of the terminal metal member that is prone to swaying near the tapered surface and faces the sensor element side approaches or contacts the rear end side of the sensor element. Therefore, the swaying of the terminal metal member can be reduced or suppressed, and the vibration of the terminal metal member is suppressed to inhibit the breakage of the terminal metal member.

[0015] In the gas sensor of the present invention, it may also be that the terminal metal member has a contact portion electrically connected to the electrode pad and a main body portion extending from the rear end side of the contact portion to the tapered surface.

[0016] According to this gas sensor, the contact portion and the main body portion are arranged in a substantially straight line, and the protrusion of the terminal metal member in the radial direction and the width direction becomes smaller. Therefore, the receiving portion 50h or the separator 50 can be made smaller and lighter in weight, and the vibration resistance can be improved.

[0017] In the gas sensor of the present invention, it may also be that the terminal metal member contacts the sensor element in a region that overlaps with the tapered surface in the axis direction.

[0018] According to this gas sensor, the plate surface of the terminal metal member that is prone to swaying near the tapered surface and faces the sensor element side contacts and is held by the rear end side of the sensor element. Therefore, the vibration of the terminal metal member can be further suppressed to further inhibit the breakage of the terminal metal member.

[0019] Effects of the Invention

[0020] According to the present invention, a gas sensor capable of suppressing the breakage of the terminal metal member on the rear end side of the separator can be obtained. Description of the Drawings

[0021] Figure 1 It is a cross-sectional view of the gas sensor according to an embodiment of the present invention.

[0022] Figure 2 It is a perspective view of the separator.

[0023] Figure 3 It isFigure 2 Cross-sectional view along line A-A

[0024] Figure 4 Is a perspective view of the connection terminal

[0025] Explanation of reference numerals

[0026] 10. Gas sensor; 20. Sensor element; 20e. Rear end of the sensor element; 20m1, 20m2. Main surfaces of the sensor element; 21a, 21b. Electrode pads; 50. Separator; 50h. Accommodating portion; 50s. Tapered surface; 71. Terminal metal member; 71c. Contact portion; 71m. Main body portion; O. Axis Detailed implementation manners

[0027] Hereinafter, in conjunction with the attached Figure 1 The implementation manners of the present invention will be described

[0028] Figure 1 Is a cross-sectional view of the gas sensor (sensor) 10 of the implementation manner of the present invention along the direction of the axis O Figure 2 Is a perspective view of the separator 50 Figure 3 Is Figure 2 Cross-sectional view along line A-A Figure 4 Is a perspective view of the connection terminal 71

[0029] 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 separator 50 that accommodates the rear end side of the sensor element 20. The gas sensor 10 is installed, for example, in the exhaust pipe of a vehicle to measure the gas components such as NO x , O2, etc. in the gas to be measured (exhaust gas).

[0030] The sensor element 20 is an elongated strip-shaped plate-like element extending in the direction of the axis O, and is formed by laminating a ceramic substrate formed of an oxygen ion conductive solid electrolyte layer such as zirconia (ZrO2). In addition, the end portion of the sensor element 20 on the protector 30 side is referred to as the front end, and the end portion of the sensor element 20 on the separator 50 side is referred to as the rear end

[0031] On the main surfaces 20m1, 20m2 of the rear end side of the sensor element 20( Figure 2 , Figure 3 ) A plurality of electrode pads 21a, 21b( Figure 3 ) are formed

[0032] Specifically, as Figure 3As 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.

[0033] In addition, the plurality of electrode pads may be arranged only on one main surface 20m1 or the main surface 20m2 of the sensor element 20.

[0034] 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 energize a heater in the case where the sensor element 20 has a heater.

[0035] As Figure 1 shown, the protector 30 is configured to surround the periphery of the front end of the sensor element 20. The protector 30 includes an inner protector 31 that covers the front end of the sensor element 20 and an outer protector 32 that covers 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 toward 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 formed of a metal such as SUS, for example.

[0036] The sensor assembly 40 includes: a main body metal housing 41, which is made of metal; an inner cylinder 42 and an outer cylinder 46, which are cylindrical and are welded and fixed to the main body metal housing 41; and a separator 50, which is connected to the rear end of the sensor element 20.

[0037] The main body metal housing 41 is mounted on, for example, an exhaust pipe of a vehicle by an external thread portion 41a. A plurality of ceramic sleeves 43a to 43c and powder filling layers 44a, 44b such as talc filled between the ceramic sleeves 43a, 43b and between the ceramic sleeves 43b, 43c are enclosed inside the inner cylinder 42, and they are sealed between a metal ring 45 and the inner wall of the main body metal housing 41.

[0038] The outer cylinder 46 covers the inner cylinder 42, the sensor element 20, and the separator 50. In addition, a rubber washer 47 closes the opening at the rear end side of the outer cylinder 46. And at the connection portion 71g on the rear end side of the terminal metal part 71 ( Figure 4 ) a lead wire 48 is connected by crimping or the like, and the lead wire 48 passes through a washer hole 47a that penetrates the washer 47 in the axis O direction and is led out from the rear end of the washer 47 to the outside.

[0039] In addition, the connection portion 71g of the terminal metal part 71 and the lead wire 48 penetrate through the washer hole 47a.

[0040] Next, the separator 50 will be described. As Figure 2 shown, the separator 50 includes: a first member 51a and a second member 51b, which are made of ceramics such as a sintered alumina body; and a fixture 90, which is made of metal, and the fixture 90 clamps and fixes the first member 51a and the second member 51b.

[0041] Further, the terminal metal member 71 is held by the first member 51a or the second member 51b, and the terminal metal member 71 is arranged so as to face and contact the electrode pads 21a and 21b of the sensor element 20 one by one.

[0042] The first member 51a and the second member 51b each hold four terminal metal members 71 arranged in the width direction orthogonal to the length direction (i.e., the axis O direction) of the terminal metal member 71. Since the first member 51a and the second member 51b have the same box shape, the same reference numerals are used to denote the same components for description. In addition, the first member 51a and the second member 51b are collectively referred to as the housing 51.

[0043] The housing 51 includes: a receiving portion 50h that penetrates in the axis O direction; four locking grooves 52 that lock the front end side of the terminal metal member 71; four insertion holes 53 into which the upright portion 71d at the center of the terminal metal member 71 is inserted; and a locking portion 54 that is formed in each insertion hole 53 and locks the terminal metal member 71.

[0044] In addition, the housing 51 has a convex portion 55 on one side in the width direction sandwiching the sensor element 20, and has restricting members 56 and 57 (see Figure 2 ) that restrict the distance in the thickness direction between the first member 51a and the second member 51b on the other side. The convex portion 55 is inserted into the concave portion between the opposing restricting members 56 and 57 of the housing 51, thereby restricting the relative position in the thickness direction between the first member 51a and the second member 51b.

[0045] As Figure 4 shown, the terminal metal member 71 is a metal member held by the housing 51 at a position facing the electrode pads 21a and 21b of the sensor element 20 one by one. The terminal metal member 71 includes: a front end portion 71a that is locked to the locking 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 and 21b by protruding bent toward the sensor element 20; an upright portion 71d that is inserted into the insertion hole 53; a bent portion 71f that leads out to the outside of the separator 50; and a connection portion 71g that crimps and holds the plurality of core wires 48a of the lead wire 48 outside the separator 50.

[0046] In addition, a portion of the terminal metal member 71 from the rear end side of the contact portion 71c to the front end side of the connection portion 71g along the axis O direction is defined as the main body portion 71m. The main body portion 71m extends to the conical surface 50s of the partition member 50 described later.

[0047] The protruding portion 71b and the contact portion 71c are arranged along the length direction of the terminal metal member 71, and the contact portion 71c is arranged closer to the connection portion 71g than the protruding portion 71b. Both the protruding portion 71b and the contact portion 71c are formed to be elastically deformable. The upright portion 71d is provided with a locking portion 71e, and the locking portion 71e is locked to the locking portion 54 by a bent shape.

[0048] In addition, the contact portion 71c of the terminal metal member 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 metal member 71 held by the second member 51b faces and contacts the electrode pad 21b of the sensor element 20 one-to-one ( Figure 3 ).

[0049] On the other hand, as Figure 3 shown, the electrode pads 21a and 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.

[0050] As Figure 2 shown, the jig 90 is formed by bending a plate-shaped metal, and the jig 90 has an elastic force capable of clamping the first member 51a and the second member 51b and pressing them in a direction approaching each other. When the first member 51a and the second member 51b are clamped by this elastic force, the restricting members 56 and 57 of the first member 51a contact the second member 51b, and the restricting members 56 and 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.

[0051] In addition, when the jig 90 clamps the first member 51a and the second member 51b in a state where the contact portion 71c of the terminal metal member 71 faces the electrode pads 21a and 21b of the sensor element 20 and the sensor element 20 and the terminal metal member 71 are clamped by 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 jig 90, respectively, to clamp and fix the sensor element 20.

[0052] At this time, by pressing through the elastic deformation of the protrusion 71b and the contact portion 71c, 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.

[0053] Next, the characteristic parts of the present invention will be described.

[0054] First, as Figure 3 shown, the separator 50 has a receiving portion 50h that penetrates in the direction of the axis O, and the receiving portion 50h receives the rear end side of the sensor element 20 and the terminal metal member 71.

[0055] More specifically, the receiving portion 50h opens on the front end face of the housing 51 as a rectangular shape slightly larger than the outer shape of the sensor element 20, and communicates with the respective insertion holes 53 on the rear end side thereof. The receiving portion 50h may also be a through hole that opens only at the front end and the rear end of the housing 51.

[0056] In addition, in this example, the receiving portion 50h is formed by respectively recessing a part of the opposing surfaces of the first member 51a and the second member 51b.

[0057] Moreover, the receiving portion 50h has a tapered surface 50s that expands in diameter in a direction perpendicular to the two main surfaces 20m1 and 20m2 of the sensor element 20 as it goes toward the rear end facing surface of the separator 50 ( Figure 3 the vertical direction).

[0058] In addition, the "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 the case where the diameter expansion degree of the tapered surface 50s varies according to the position. For example, it also includes the case where the tapered surface 50s is not parallel to the main surfaces 20m1 and 20m2, the case where the tapered surface 50s is a curved surface, and the case 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 (the case 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.

[0059] On the other hand, in this example, the terminal metal member 71 is plate-shaped, and the plate surface faces the main surfaces 20m1 and 20m2 of the sensor element 20. Since the plate-shaped terminal metal member 71 oscillates in the direction perpendicular to the plate surface, due to vibrations during the use of the gas sensor 10 or the like, the terminal metal member 71 oscillates in the direction perpendicular to the main surfaces 20m1 and 20m2 ( Figure 3 the V direction) and is easily broken.

[0060] Therefore, as Figure 3As shown, the rear end 20e of the sensor element 20 is disposed inside the conical surface 50s (within the region R) along the direction of the axis O. Thus, the plate surface of the terminal metal piece 71, which is prone to oscillating in the V direction near the conical surface 50s and facing the sensor element 20 side, approaches or contacts the rear end side of the sensor element 20. Therefore, the oscillation of the terminal metal piece 71 in the V direction can be reduced or suppressed, and the vibration of the terminal metal piece 71 can be suppressed to inhibit the breakage of the terminal metal piece 71.

[0061] In addition, if the rear end 20e of the sensor element 20 protrudes rearward from the rear end of the partition member 50 (i.e., deviates from the region R), there may be problems such as the sensor element 20 itself being prone to oscillating due to vibration or interference with the rear end 20e of the sensor element 20 when the gasket 47 is disposed on the rear end side of the partition member 50.

[0062] Furthermore, in this example, the terminal metal piece 71 has a contact portion 71c electrically connected to the electrode pads 21a and 21b and a main body portion 71m extending from the rear end side of the contact portion 71c to the conical surface 50s.

[0063] Thus, the contact portion 71c and the main body portion 71m are arranged in a substantially straight line, and the protrusion of the terminal metal piece 71 in the radial and width directions becomes smaller. Therefore, the accommodating portion 50h or the partition member 50 can be made smaller and lighter, improving the vibration resistance.

[0064] In addition, preferably, the terminal metal piece 71 contacts the sensor element 20 in the region where it overlaps the conical surface 50s in the direction of the axis O.

[0065] Thus, the plate surface of the terminal metal piece 71, which is prone to oscillating in the V direction near the conical surface 50s and facing the sensor element 20 side, contacts the rear end side of the sensor element 20 and is held. Therefore, the vibration of the terminal metal piece 71 can be further suppressed to further inhibit the breakage of the terminal metal piece 71.

[0066] The present invention is not limited to the above-described embodiments, and of course, relates to various modifications and equivalents included within the spirit and scope of the present invention.

[0067] The partition member 50 is not limited to a box shape divided into two parts, and may also be a cylindrical shape such as a cylinder.

Claims

1. A gas sensor comprising: A sensor element having a plate shape, the sensor element extending in the axial direction and having an electrode pad on a main surface on the rear end side; a terminal metal member extending along the axial direction and electrically connected to the electrode pad; and a separator having a housing portion which penetrates in the axial direction, the housing portion housing the rear end side of the sensor element and the terminal metal fitting, the separator holding the terminal metal 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 moves toward the rear end of the partition. The rear end of the sensor element is arranged inside the tapered surface along the axial direction.

2. The gas sensor according to claim 1, characterized in that The terminal metal fitting includes a contact portion electrically connected to the electrode pad and a main body portion extending from the rear end side of the contact portion to the tapered surface.

3. The gas sensor according to claim 1 or 2, characterized in that: The terminal metal fitting is in contact with the sensor element in a region overlapping with the tapered surface in the axial direction.

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