Gas sensor

Abstract

The invention provides a gas sensor which suppresses the risk of damage of components constituting the gas sensor and prevents a ceramic housing from moving to the front end side in the axial direction. A gas sensor according to one aspect of the present invention is provided with a hollow member disposed between a main body fitting and a ceramic case, and the hollow member is made of a material having a Young's modulus of 193-206 GPa.

Description

Technical Field

[0001] The present invention relates to a gas sensor. Background Art

[0002] In the past, there are known gas sensors that detect the concentration of specific gases such as oxygen and NOx in the measured gas such as automobile exhaust. For example, the following patent document 1 discloses a gas sensor, which includes: a sensor element; a main metal part that surrounds the periphery of the sensor element; a metal outer cylinder that is mounted on the rear end side of the main metal part; and a rubber cap that closes the rear end side opening of the outer cylinder. In the gas sensor of patent document 1, the electrode terminal part arranged on the rear end side of the sensor element is connected to the front end side connection part of the terminal metal part, and the front end side connection part and the part of the sensor element having the electrode terminal part are housed inside the separator (ceramic shell). In addition, the separator is arranged inside the outer cylinder in a state of being clamped and fixed between the rubber cap and the front end side component located on the front end side relative to the separator.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-173747 Summary of the invention

[0006] The inventors of the present invention have discovered a problem in that the conventional gas sensor disclosed in Patent Document 1 has a high risk of damage to components constituting the gas sensor.

[0007] That is, in the conventional gas sensor, the spacer is sandwiched by the rubber cap and the front end side component, thereby preventing the spacer from moving in the axial direction of the gas sensor. In particular, in the conventional gas sensor, the spacer is prevented from moving toward the front end side of the gas sensor by the front end side component. Therefore, the front end side component extends to a position closer to the rear end side than the main metal part surrounding the periphery of the sensor element in a manner of contacting the spacer, for example, extending longer toward the rear end side than the main metal part. In addition, as described above, the sensor element is connected to the terminal metal part inside the spacer, so the sensor element axially penetrates the interior of the front end side component located at the front end side relative to the spacer. That is, in the conventional gas sensor, the sensor element axially penetrates the interior of the front end side component extending in the axial direction (for example, extending longer toward the rear end side than the main metal part). Therefore, in the conventional gas sensor, for example, when the front end side component is tilted from the axial direction, the sensor element extending in the axial direction sometimes interferes with the front end side component, causing the element to break.

[0008] In addition, in conventional gas sensors, the front end side member and the spacer are in contact, so when an impact is applied to the gas sensor, the contact portion between the front end side member and the spacer may be damaged. In particular, when the front end side member and the spacer are made of the same material, for example, when both are made of ceramics such as alumina, the possibility of damage to the contact portion is further increased.

[0009] One aspect of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas sensor that suppresses the risk of damage to components constituting the gas sensor and prevents a ceramic housing from moving toward the front end side in the axial direction.

[0010] The present invention adopts the following configurations in order to solve the above-mentioned problems.

[0011] The gas sensor according to the first aspect comprises: a sensor element extending in the axial direction and having a connector electrode on the rear end side; a cylindrical main body metal fitting, the sensor element passing through the main body metal fitting in the axial direction; a cylindrical outer tube, the outer tube extending in the axial direction and being mounted on the outer peripheral surface on the rear end side of the main body metal fitting; a terminal metal fitting extending in the axial direction and having an element contact portion electrically connected to the connector electrode on the front end side; a ceramic shell that accommodates the connector electrode and the element contact portion and is arranged inside the outer tube; an elastic body that is arranged in a manner to close the open end on the rear end side of the outer tube; and a hollow member that is arranged inside the outer tube, the sensor element passing through the hollow member in the axial direction, contacting the rear end side of the main body metal fitting on the front end side in the axial direction, and contacting the front end side of the ceramic shell on the rear end side in the axial direction, and is made of a material with a Young's modulus of 193 to 206 GPa.

[0012] Regarding this configuration, in the gas sensor, the hollow component contacts the rear end side of the main metal member at the front end side in the axial direction, that is, the movement toward the front end side is restricted by the main metal member. Furthermore, the ceramic shell contacts the hollow component whose movement toward the front end side is restricted. Therefore, in the gas sensor, the movement of the ceramic shell toward the front end side is restricted by the hollow component, that is, the hollow component prevents the ceramic shell from moving toward the front end side.

[0013] Furthermore, in the gas sensor, the Young's modulus of a material constituting the hollow member is 193 to 206 GPa.

[0014] The inventors of the present invention believe that by making the hollow component soft enough, the ceramic shell in contact with the hollow component can be suppressed from being damaged, etc. In addition, the inventors of the present invention believe that by making the hollow component have sufficient hardness, the ceramic shell can be reliably (stably) prevented from moving toward the front end side by utilizing the hollow component. Therefore, the inventors of the present invention experimentally verified the mechanical properties of the material constituting the hollow component that can suppress the ceramic shell from being damaged, etc. and can reliably prevent the ceramic shell from moving toward the front end side. As a result, the inventors of the present invention confirmed that by making the Young's modulus of the material constituting the hollow component 193 to 206 GPa, the above two requirements can be met. That is, the inventors of the present invention confirmed that by making the Young's modulus of the material constituting the hollow component 193 to 206 GPa, the ceramic shell can be significantly suppressed from being damaged, etc., and the ceramic shell can be reliably prevented from moving toward the front end side.

[0015] Therefore, the hollow member made of a material having a Young's modulus of 193 to 206 GPa can significantly suppress the ceramic shell from being damaged, and can reliably prevent the ceramic shell from moving toward the front end side.

[0016] Therefore, the gas sensor can achieve the effect of suppressing the risk of damage to the components constituting the gas sensor and preventing the ceramic housing from moving toward the front end side in the axial direction.

[0017] The gas sensor according to the second aspect is the gas sensor according to the first aspect, wherein the hollow member may be formed of a thin plate having a thickness of 0.3 to 0.8 mm. In this configuration, in the gas sensor, the hollow member is formed of a thin plate having a thickness of 0.3 to 0.8 mm.

[0018] Here, there is a heat source at the front end side of the gas sensor, so the heat released from the heat source may be transferred to the ceramic shell via the hollow component, and then transferred to the elastomer via the ceramic shell. In addition, when the heat is transferred to the ceramic shell, for example, the contact between the connector electrode and the contact part of the element sometimes becomes hot and oxidizes the contact, increasing the contact resistance. In addition, when the heat is transferred to the elastomer, the elastomer may melt. In addition, when the elastomer melts, the reference gas (reference air) in the outer cylinder may be contaminated or the shock resistance of the gas sensor may deteriorate. In addition, sometimes the electrode of the sensor element (for example, a reference electrode configured to be in contact with the reference gas) is contaminated by the organic gas associated with the thermal decomposition of the elastomer.

[0019] Therefore, the inventor of the present invention worked on the structure of the hollow component and explored maintaining the strength of the hollow component to prevent the ceramic shell from moving toward the front end side in the axial direction and suppressing heat transfer to the ceramic shell. The inventor of the present invention confirmed through experiments that by forming the hollow component with a thin plate with a thickness of 0.3 to 0.8 mm, the strength of the hollow component can be maintained and heat transfer to the ceramic shell can be significantly suppressed. The inventor of the present invention confirmed that the thin plate with a thickness of 0.3 to 0.8 mm has sufficient strength to prevent the ceramic shell from moving toward the front end side in the axial direction, and has sufficient heat capacity to suppress heat transfer to the ceramic shell.

[0020] Therefore, the hollow member formed of a thin plate having a thickness of 0.3 to 0.8 mm has sufficient strength to prevent the ceramic shell from moving toward the front end side in the axial direction, and can significantly suppress heat transfer to the ceramic shell.

[0021] Therefore, the gas sensor can suppress the risk of damage to the components constituting the gas sensor and prevent the ceramic housing from moving toward the front end side in the axial direction, thereby improving the heat resistance of the gas sensor.

[0022] The gas sensor involved in the third viewpoint is based on the gas sensor involved in the first or second viewpoint, and the hollow component can be composed of multiple components. Regarding this structure, in the gas sensor, the hollow component is composed of the multiple components, that is, the hollow component composed of a material with a Young's modulus of 193 to 206 GPa is composed of the multiple components. For example, the hollow component is composed of the multiple components, and the multiple components are respectively composed of a material with a Young's modulus of 193 to 206 GPa. Therefore, the gas sensor exerts the following effect: the hollow component composed of a material with a Young's modulus of 193 to 206 GPa can be easily constructed by the multiple components.

[0023] The gas sensor involved in the fourth aspect is based on the gas sensor involved in any one of the first to third aspects mentioned above, wherein the hollow component and the main metal part can be integrally formed. Regarding this structure, in the gas sensor, the hollow component and the main metal part are integrally formed. Therefore, the gas sensor exerts the following effect: the hollow component that can suppress the risk of damage to the components constituting the gas sensor and prevent the ceramic shell from moving toward the front end side in the axial direction can be easily formed together with the main metal part. In addition, the gas sensor exerts an effect of being able to suppress the number of components constituting the gas sensor.

[0024] The gas sensor involved in the fifth aspect is based on the gas sensor involved in any one of the first to fourth aspects mentioned above, wherein the ceramic shell can be isolated from the elastomer. Regarding this configuration, in the gas sensor, the ceramic shell is isolated from the elastomer, that is, it is not in contact with the elastomer. By isolating the elastomer from the ceramic shell that is configured to be closer to the front end side than the elastomer in the axial direction, the gas sensor exerts the following effect. That is, the gas sensor exerts the following effect: it is possible to prevent heat released from a heat source located at the front end side of the gas sensor from being transferred to the elastomer via the ceramic shell, thereby preventing the elastomer from melting due to the heat.

[0025] It should be noted that, for example, in the gas sensor, the inner circumferential surface of the outer cylinder that houses the ceramic shell may include a portion (locking portion) inclined from the axial direction, and may include a portion (locking portion) orthogonal to the axial direction, for example. The ceramic shell contacts the above-mentioned locking portion at the inner circumferential surface of the outer cylinder at the rear end side in the axial direction, thereby limiting the movement of the ceramic shell toward the rear end side in the axial direction. Therefore, the gas sensor can prevent the ceramic shell from moving toward the rear end side in the axial direction without contacting the ceramic shell and the elastomer.

[0026] The gas sensor involved in the sixth aspect is based on the gas sensor involved in any one of the first to fifth aspects mentioned above, wherein the main metal part may include a surface orthogonal to the axial direction on the rear end side, and the hollow part is in contact with the surface of the main metal part orthogonal to the axial direction. Regarding this structure, in the gas sensor, the main metal part includes a surface orthogonal to the axial direction on the rear end side, and the hollow part is in contact with the surface of the main metal part orthogonal to the axial direction. Therefore, the gas sensor exerts the following effect: the hollow part can be easily and stably positioned in the axial direction by utilizing the surface orthogonal to the axial direction of the main metal part, and in particular, the movement of the hollow part to the front end side can be easily and stably restricted. In addition, in the gas sensor, by easily and stably positioning the hollow part in the axial direction, the ceramic shell whose movement to the front end side is restricted by the hollow part can also be easily and stably positioned in the axial direction.

[0027] The gas sensor involved in the seventh aspect is based on the gas sensor involved in any one of the first to sixth aspects mentioned above, wherein the hollow part can be isolated from the sensor element. With regard to this configuration, in the gas sensor, the hollow part is isolated from the sensor element, that is, the hollow part and the sensor element are not in contact. Therefore, the gas sensor has the following effect: it is possible to reduce the risk of interference between the hollow part and the sensor element, causing the element to break, etc. For example, even if an external force is applied to the gas sensor, causing the hollow part to tilt from the axial direction, the hollow part will not interfere with the sensor element because it is isolated from the sensor element.

[0028] The gas sensor involved in the eighth aspect may further include a spacer, which is arranged between the ceramic shell and the elastomer in the axial direction, on the basis of the gas sensor involved in any one of the first to seventh aspects. Regarding this structure, in the gas sensor, the elastomer is arranged to be closer to the rear end side than the ceramic shell and the spacer in the axial direction. Therefore, the gas sensor exerts the following effect: through the ceramic shell and the spacer, it is possible to effectively suppress the heat released from the heat source located on the front end side of the gas sensor from being transferred to the elastomer. It should be noted that the spacer arranged to be closer to the front end side than the elastomer in the axial direction is preferably made of a heat-resistant material. By using a heat-resistant material to constitute the spacer, it is possible to prevent the spacer arranged to be closer to the front end side than the elastomer in the axial direction from being melted due to the heat released from the heat source.

[0029] Effects of the Invention

[0030] According to the present invention, it is possible to provide a gas sensor that suppresses the risk of damage to components constituting the gas sensor and prevents the ceramic housing from moving toward the front end side in the axial direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a cross-sectional schematic diagram schematically showing an example of the structure of the gas sensor according to the embodiment.

[0032] Figure 2 Yes Figure 1 FIG. 1 is an enlarged cross-sectional view of a main part showing an arrangement state of a hollow member of a gas sensor illustrated in FIG.

[0033] Figure 3 It is a cross-sectional schematic diagram schematically showing an example of the configuration of a gas sensor according to Modification 1.

[0034] Figure 4 This is a cross-sectional schematic diagram schematically showing an example of the structure of a gas sensor according to Modification 2.

[0035] Explanation of symbols

[0036] 1, 1A, 1B…gas sensor; 10…sensor element; 12…connector electrode; 21…main body metal part; 22, 22A, 22B…outer cylinder; 30…terminal metal part; 31…element contact part; 50…elastic body; 60…ceramic shell; 70, 70A…hollow part; 100…spacer. DETAILED DESCRIPTION

[0037] Hereinafter, an embodiment (hereinafter also referred to as "the present embodiment") according to one aspect of the present invention will be described based on the accompanying drawings. However, the present embodiment described below is merely an example of the present invention in all aspects. Of course, various improvements and modifications may be made without departing from the scope of the present invention. That is, when implementing the present invention, a specific configuration corresponding to the embodiment may be appropriately adopted.

[0038] [Configuration example]

[0039] <Overview of Gas Sensor>

[0040] Figure 1 1 is a cross-sectional schematic diagram schematically showing an example of the main structure of the gas sensor 1 of the present embodiment. Figure 1 The structure of the cross section of the gas sensor 1 which is parallel to and in contact with the axis in the longitudinal direction (axis line AL, a line along the left-right direction in the figure) is schematically shown. The gas sensor 1 is an example of the "gas sensor" of the present invention, which is a gas sensor capable of detecting the concentration of specific gases such as oxygen and NOx (specific gas concentration) in the measured gas such as automobile exhaust gas. Figure 1 As shown in the example, the gas sensor 1 has an axis and extends in the longitudinal direction (axial direction), and has a front end and a rear end as respective ends in the longitudinal direction. One end in the longitudinal direction is the front end, and the other end is the rear end. Figure 1 In the example of , the gas sensor 1 is arranged such that the front end of the gas sensor 1 faces the left, and the rear end of the gas sensor 1 faces the right. That is, Figure 1 The left-right direction in corresponds to the longitudinal direction (axial direction).

[0041] The gas sensor 1 of the present embodiment includes at least a sensor element 10 , a main body metal fitting 21 , an outer cylinder 22 , a terminal metal fitting 30 , an elastic body 50 , a ceramic case 60 , and a hollow member 70 . Figure 1 The gas sensor 1 illustrated in the figure further includes: a fixing bolt 23, a lead wire 40, a protective cover 80, and a surrounding assembly member 90. In the gas sensor 1, the sensor element 10 is surrounded by the cylindrical body 20 and the protective cover 80, and the cylindrical body 20 and the protective cover 80 constitute a storage member (housing) that stores the sensor element 10. The sensor element 10 is coaxially arranged with the cylindrical body 20 and the protective cover 80, and the extension direction of the central axis of the sensor element 10 is consistent with the axial direction of the gas sensor 1.

[0042] (Sensor element)

[0043] The sensor element 10 is an example of the “sensor element” of the present invention, and is configured to be Figure 1 The left and right directions in the figure extend. Figure 1The sensor element 10 illustrated in FIG. 1 is an elongated flat plate-shaped (long strip-shaped) element. The sensor element 10 has a detection portion 11 on the front end side and a connector electrode 12 on the rear end side. Figure 1 The front end side of the sensor element 10 illustrated in FIG. 1 is covered with an outer porous layer. The outer porous layer functions as a protective layer that suppresses cracking of the element body of the sensor element 10 due to adhesion of moisture in the measured gas, for example.

[0044] In the gas sensor 1, the sensor element 10 is arranged such that the front end side faces the front end of the gas sensor 1. For example, in one embodiment of the sensor element 10, the gas to be measured introduced into the inside of the sensor element 10 is reduced or decomposed inside the sensor element 10 to generate oxygen ions. In the gas sensor 1 having such a sensor element 10, the amount of oxygen ions flowing inside the sensor element 10 is proportional to the concentration of the monitoring target gas, that is, the specific gas in the gas to be measured, and based on this, the concentration of the specific gas is calculated.

[0045] Figure 1 In the example shown, the front end side of the sensor element 10 is surrounded by a protective cover 80, and the rear end side protrudes into the outer tube 22. The approximately central portion between the two is fixed to the inside of the main metal part 21 by means of a surrounding assembly component 90 in a manner that hermetically seals the two ends.

[0046] (Wrap-around assembly)

[0047] Figure 1 In the example shown, the surrounding assembly component 90 includes: a first ceramic support 91, a powder compact 92, and a second ceramic support 93. The first ceramic support 91 and the second ceramic support 93 are ceramic insulators. More specifically, a through hole (not shown) having a shape corresponding to the cross-sectional shape of the sensor element 10 is provided at the axial center position of the first ceramic support 91 and the second ceramic support 93, and the sensor element 10 is inserted into the through hole, thereby the first ceramic support 91 and the second ceramic support 93 are mounted around the sensor element 10. It should be noted that the first ceramic support 91 is clamped to the tapered surface of the main metal member 21 on the left side of the figure.

[0048] On the other hand, the powder compact 92 is obtained by molding ceramic powders such as talc. The powder compact 92 has the sensor element 10 inserted in the through hole in the same manner as the first ceramic support 91 and the second ceramic support 93, and the two molded bodies (not shown) assembled around the sensor element 10 are arranged inside the main metal part 21 in a state of being assembled around the sensor element 10, and then further compressed to become one. In more detail, the ceramic particles forming the powder compact 92 are surrounded by the first ceramic support 91, the second ceramic support 93 and the main metal part 21, and are tightly filled in the space inside the main metal part 21 for the sensor element 10 to pass through. The compressed filling of the powder compact 92 realizes the airtight closure between the front end side and the rear end side of the sensor element 10.

[0049] Figure 1 2 shows an example in which the surrounding assembly member 90 is composed of the first ceramic support 91, the powder compact 92, and the second ceramic support 93. However, in the gas sensor 1, it is not essential that the surrounding assembly member 90 is composed of the first ceramic support 91, the powder compact 92, and the second ceramic support 93. Figure 1 The gas sensor 1 illustrated in FIG. 1 has a sensor element 10 fixed inside a metal body 21 and includes a surrounding mounting member 90 that hermetically seals a space between the front end side and the rear end side of the sensor element 10 .

[0050] (Tubular body)

[0051] The cylindrical body 20 is a cylindrical (eg, cylindrical) member made of metal, for example, and has an open end. The sensor element 10 is disposed inside the cylindrical body 20 . Figure 1 In the example shown, the cylindrical body 20 includes a cylindrical main body metal fitting 21 , a cylindrical outer cylinder 22 , and a fixing bolt 23 , all of which are metal parts.

[0052] The main body metal fitting 21 is an example of the "main body metal fitting" of the present invention, and is, for example, a metal cylindrical (a cylindrical one example) component. The sensor element 10 and the surrounding mounting component 90 for fixing and surrounding the sensor element 10 are accommodated inside the main body metal fitting 21. That is, the main body metal fitting 21 is further surrounded by the surrounding mounting component 90 surrounding the sensor element 10. Figure 1 The main metal fitting 21 illustrated in the figure is configured to surround the sensor element 10 in the axial direction (length direction), and is particularly configured to surround the sensor element 10 except for a portion of each of the front end side and the rear end side. That is, the main metal fitting 21 is a cylindrical member in which the sensor element 10 penetrates in the axial direction, and surrounds the sensor element 10, and particularly surrounds the sensor element 10 except for a portion of each of the front end side and the rear end side.

[0053] The outer cylinder 22 is an example of the “outer cylinder” of the present invention, and is a tubular (eg, cylindrical) member extending in the axial direction, and is made of, for example, metal. Figure 1 The outer cylinder 22 illustrated in FIG. 1 covers the rear end of the sensor element 10 , the hollow member 70 , and the periphery of the ceramic case 60 (the terminal metal fitting 30 ).

[0054] The outer cylinder 22 is attached to a portion on the rear end side of the metal shell 21 , for example, is mounted on the outer peripheral surface on the rear end side of the metal shell 21 . Figure 1 In the example shown, the end (open end) of the front end side of the outer cylinder 22 is assembled to the outer peripheral end of the rear end side of the main metal fitting 21, for example, welded and fixed to the outer peripheral end of the rear end side of the main metal fitting 21. In addition, the elastic body 50 is arranged at the open end of the rear end side of the outer cylinder 22 in a manner to close the open end. A reduced diameter portion 221 is formed on the rear end side of the outer cylinder 22 to which a part of the elastic body 50 for closing the open end of the rear end side is riveted from the periphery. At the reduced diameter portion 221, the entire circumference of the outer cylinder 22 is riveted from the outside to a reduced diameter shape, thereby causing the elastic body 50 to generate a reaction force toward the radial outside, so that the outer cylinder 22 is closed.

[0055] In addition, the lead wire 40 is led out to the outside through a through hole (not shown) formed inside the elastic body 50 from the open end on the rear end side of the outer cylinder 22 closed by the elastic body 50. The internal space of the outer cylinder 22 becomes a reference gas (air) atmosphere, and the rear end of the sensor element 10 is arranged in the internal space of the outer cylinder 22 filled with the reference gas. For example, the external gas (air) is introduced into the internal space of the outer cylinder 22 through the gap between the film of the lead wire 40 and the metal wire (conductor) (in other words, the inside of the film), so that the internal space of the outer cylinder 22 can become the reference gas (air) atmosphere. However, the structure for introducing the reference gas into the internal space of the outer cylinder 22 is not limited to the above structure, and the reference gas can be introduced into the internal space of the outer cylinder 22 through a reference gas introduction path (reference gas introduction hole) not shown in the figure other than "between the film of the lead wire 40 and the metal wire".

[0056] The fixing bolt 23 is an annular member used when fixing the gas sensor 1 at the measurement position (installation position), and is fixed coaxially with the main metal member 21. The fixing bolt 23 includes: a bolt portion obtained by thread cutting, and a retaining portion that is retained when the bolt portion is screwed in. The bolt portion of the fixing bolt 23 is screwed into a nut provided at the installation position of the gas sensor 1. For example, by screwing the bolt portion of the fixing bolt 23 into a nut (nut portion) provided in the exhaust pipe of the automobile, the gas sensor 1 is fixed to the exhaust pipe in a manner that the protective cover 80 side is exposed in the exhaust pipe.

[0057] As described above, for example, the cylindrical body 20 (the main metal fitting 21, the outer cylinder 22, and the fixing bolt 23) and the gas sensor 1 (the sensor element 10) are coaxial, and the cylindrical body 20 has a front end and a rear end as each end in the axial direction (length direction). In addition, the cylindrical body 20 is configured so that its front end faces the front end of the gas sensor 1. The sensor element 10, the surrounding assembly component 90 for fixing the sensor element 10, the hollow component 70, and the ceramic shell 60 (terminal metal fitting 30) are accommodated inside the cylindrical body 20, and the open end on the rear end side is closed by the elastomer 50. A reduced diameter portion 221 for fixing the elastomer 50 that closes the open end of the cylindrical body 20 is formed on the rear end side of the cylindrical body 20 (outer cylinder 22), and the reduced diameter portion 221 rivets a part of the elastomer 50 from the periphery.

[0058] It should be noted that in the gas sensor 1, it is not necessary for the cylindrical body 20 to include the fixing bolts 23, and the cylindrical body 20 may not include the fixing bolts 23. In addition, in the cylindrical body 20, the main metal part 21 and the outer cylinder 22 may be an integrally formed component. In the gas sensor 1, the cylindrical body 20 only needs to be a cylindrical component in which the sensor element 10 is arranged and an open end is formed.

[0059] (Terminal metal parts)

[0060] The terminal metal fitting 30 is an example of the "terminal metal fitting" of the present invention. The terminal metal fitting 30 is a metal component (contact component) extending in the axial direction. In the gas sensor 1, the sensor element 10 (especially its connector electrode 12) and the wire 40 are electrically connected by means of the terminal metal fitting 30. The terminal metal fitting 30 has an element contact portion 31 electrically connected to the connector electrode 12 of the sensor element 10 on the front end side, and also has a wire holding portion for crimping and holding the wire 40 on the rear end side.

[0061] (Ceramic housing)

[0062] The ceramic shell 60 is an example of the "ceramic shell" of the present invention, and is arranged (housed) inside the outer cylinder 22. The ceramic shell 60 can be configured as a cylindrical component extending in the axial direction, for example, it can be configured as a cylindrical component extending in the axial direction. The ceramic shell 60 is a ceramic component that houses the rear end side of the sensor element 10 (specifically, the connector electrode 12 provided on the rear end side of the sensor element 10) and the element contact portion 31 of the terminal metal fitting 30. That is, Figure 1 In the gas sensor 1 illustrated in FIG. 8 , the sensor element 10 (particularly the connector electrode 12 ) and the terminal metal fitting 30 (particularly the element contact portion 31 ) are electrically connected within the ceramic case 60 .

[0063] For example, the rear end side of the sensor element 10 provided with the connector electrode 12 is inserted into the ceramic housing 60 that accommodates the front end side (element contact portion 31) of the terminal metal fitting 30. In this inserted state, the connector electrode 12 provided on the rear end side of the sensor element 10 and the front end side (element contact portion 31) of the terminal metal fitting 30 are in contact with each other. The connector electrode 12 of the sensor element 10 and the terminal metal fitting 30 can also be electrically connected by clamping and fixing the front end side (element contact portion 31) of the terminal metal fitting 30 between the rear end side of the sensor element 10 provided with the connector electrode 12 and the ceramic housing 60.

[0064] Figure 1 In the gas sensor 1 illustrated in FIG. 1 , there is a gap between the ceramic shell 60 and the cylindrical body 20 (outer cylinder 22), that is, the ceramic shell 60 is not in contact with the cylindrical body 20. That is, the ceramic shell 60 is arranged inside the outer cylinder 22 in a manner separated from the inner peripheral surface of the outer cylinder 22. For the ceramic shell 60, for example, by being integrated with the sensor element 10, its position (radial position) inside the outer cylinder 22 can be fixed without contacting the inner peripheral surface of the outer cylinder 22. As described above, the position of the sensor element 10 inside the cylindrical body 20 is fixed by surrounding the assembly component 90 and the cylindrical body 20 (particularly the main metal part 21 and the outer cylinder 22). Therefore, since the ceramic shell 60 is integrated with the sensor element 10 whose position inside the cylindrical body 20 is fixed by surrounding the assembly component 90 and the cylindrical body 20, the position of the ceramic shell 60 inside the cylindrical body 20 can be fixed without contacting the cylindrical body 20. However, the gas sensor 1 does not necessarily need to fix the position of the ceramic case 60 inside the outer tube 22 in a state where the ceramic case 60 and the inner circumferential surface of the outer tube 22 are isolated from each other by integrating the ceramic case 60 and the sensor element 10 .

[0065] (wire)

[0066] The lead wire 40 is electrically connected to the connector electrode 12 of the sensor element 10 by means of the terminal metal fitting 30, and extends outward (e.g., the rear end side) from the open end of the cylindrical body 20. Specifically, the lead wire 40 is electrically connected to the rear end side of the terminal metal fitting 30 (specifically, the lead wire holding portion of the terminal metal fitting 30) at its front end side, and the rear end side of the lead wire 40 extends outward from the open end of the cylindrical body 20. And, as described above, the gap between the lead wire 40 and the cylindrical body 20 (outer cylinder 22) is closed by the elastic body 50.

[0067] For example, the wire 40 is inserted into a through hole (not shown) provided in the elastic body 50. The end of the front end side of the wire 40 is crimped and fixed to the rear end side (wire holding portion) of the terminal metal fitting 30, and the end of the rear end side of the wire 40 is connected to an external device (controller), power source, etc. Accordingly, the sensor element 10 (particularly the connector electrode 12 of the sensor element 10) and the external device, power source, etc. are electrically connected through the terminal metal fitting 30 and the wire 40. It should be noted that Figure 1 2 shows an example in which two terminal metal fittings 30 and two lead wires 40 are provided, but this is merely to simplify the illustration. In reality, the gas sensor 1 includes the number of terminal metal fittings 30 and lead wires 40 required for the above-mentioned electrical connection.

[0068] (Elastomer)

[0069] The elastic body 50 is an example of the "elastic body" of the present invention. The elastic body 50 is a member having elasticity, for example, made of rubber. The elastic body 50 is configured to extend the open end ( Figure 1 In the example shown, the rear end side opening end is closed, for example, the rear end side opening end (opening portion) of the outer tube 22 is closed and fixed to the outer tube 22 by the reduced diameter portion 221. Figure 1 In the example shown, the wire 40 is inserted into the elastic body 50. Specifically, a through hole extending in the axial direction is formed inside the elastic body 50, for example, a plurality of through holes extending in the axial direction are formed. The through hole formed inside the elastic body 50 accommodates (inserts) the wire 40, for example, each of the plurality of wires 40 is accommodated (inserted) in the plurality of through holes formed inside the elastic body 50.

[0070] The material of the elastomer 50 is, for example, fluororubber. Fluororubber has excellent properties in various aspects such as tolerance and strength, and in particular, excellent heat resistance and oil resistance. Therefore, the gas sensor 1 exerts the following effects: by utilizing the elastomer 50 formed of fluororubber, for example, the sealing of the elastomer 50 can be ensured even in a high temperature environment to maintain and improve the detection accuracy of the gas concentration. However, for the gas sensor 1, it is not necessary to set the material of the elastomer 50 to fluororubber. In the gas sensor 1, a raw material with elasticity can be appropriately used for the material of the elastomer 50.

[0071] (Protective cover)

[0072] The protective cover 80 is a substantially cylindrical outer member that protects a portion of the sensor element 10 that directly contacts the gas to be measured during use, that is, a predetermined range on the tip side. Figure 1The protective cover 80 illustrated in the figure is configured to surround at least a portion of the front end side of the cylindrical body 20 (main metal part 21) along the axial direction (length direction) and extend in a manner exceeding the front end of the sensor element 10. For example, the protective cover 80 is configured to surround the sensor element 10 and a portion of the front end side of the cylindrical body 20 around the axis. The protective cover 80 has a front end and a rear end as each end in the axial direction, and the front end of the protective cover 80 is arranged to be closer to the front end side of the gas sensor 1 than the front end of the sensor element 10.

[0073] The protective cover 80 is provided with a plurality of through holes (not shown) through which gas can pass. The gas to be measured that flows into the protective cover 80 through the through holes is a direct monitoring object of the sensor element 10. It should be noted that the type, number, position, shape, etc. of the through holes provided in the protective cover 80 can be appropriately determined in consideration of the flow pattern of the gas to be measured toward the inside of the protective cover 80.

[0074] Figure 1 In the example shown, the protective cover 80 includes: an inner cover 81 with a bottomed cylindrical shape that covers the front end of the sensor element 10, and an outer cover 82 with a bottomed cylindrical shape that covers the inner cover 81. The inner cover 81 is configured to include a first component 81B and a second component 81A, and covers the sensor element 10 and at least a portion of the front end side of the cylindrical body 20 (main metal part 21). The first component 81B is configured to extend axially from the outer wall of the front end of the cylindrical body 20, reduce the diameter in a direction perpendicular to the axial direction near the front end of the cylindrical body 20, and then further extend axially. The second component 81A is configured to cover the periphery of a portion of the front end side of the first component 81B. The outer cover 82 is configured to cover the periphery of the inner cover 81.

[0075] As a space surrounded by the inner cover 81, a sensor element chamber is formed, and the front end of the sensor element 10 is arranged in the sensor element chamber. Openings are appropriately provided in the first part 81B, the second part 81A and the outer cover 82 of the inner cover 81, and the sensor element chamber is connected to the space outside the protective cover 80. However, the structure and shape of the protective cover 80 are not limited to such an example. The structure and shape of the protective cover 80 can be appropriately determined according to the embodiment.

[0076] The material of the protective cover 80 may be a metal material such as stainless steel (eg, SUS). The protective cover 80 may be manufactured by appropriately molding the metal material. It should be noted that the protective cover 80 may be omitted from the configuration of the gas sensor 1 .

[0077] (Hollow parts)

[0078] The gas sensor 1 includes a hollow member 70 to suppress the risk of damage to the members constituting the gas sensor 1 and to prevent the ceramic housing 60 from moving toward the front end in the axial direction. The hollow member 70 is an example of the “hollow member” of the present invention. Figure 1 The hollow component 70 illustrated in the figure includes, for example, two cylindrical parts (in the example shown in the figure, the first part 71 and the second part 72) having different outer diameters and arranged coaxially, and the whole is configured as a cylindrical component whose outer diameter changes in the axial direction. That is, the hollow component 70 is a hollow component with a cylindrical (columnar) appearance. Specifically, the hollow component 70 includes: a first part 71 arranged at the front end side in the axial direction, and a second part 72 arranged to be closer to the rear end side than the first part 71 in the axial direction and having a smaller outer diameter than the first part 71. The outer diameter of the hollow component 70 changes in the axial direction. In the example shown in the figure, the outer diameter of the hollow component 70 changes at the connecting part of the first part 71 and the second part 72. Specifically, the outer diameter of the hollow component 70 becomes smaller at the connecting part of the first part 71 and the second part 72.

[0079] It should be noted that, for the hollow component of one embodiment of the present invention, it is not necessary that the outer diameter of the first portion 71 and the outer diameter of the second portion 72 are different, and the outer diameters of the two portions can be the same. In addition, for the hollow component 70, it is not necessary that the outer diameter of the second portion 72 is smaller than the outer diameter of the first portion 71. In addition, Figure 1 In the example shown, the outer diameter of the hollow member 70 changes at the connection portion between the first portion 71 and the second portion 72. However, the outer diameter of the hollow member 70 may change continuously or discontinuously from the opening on the front end side (the opening on the front end side of the first portion 71) toward the opening on the rear end side (the opening on the rear end side of the second portion 72).

[0080] The first portion 71 is a cylindrical portion of the hollow member 70 disposed on the front end side and in contact with the rear end side of the main body metal fitting 21. Figure 1 In the example shown, the second portion 72 is in contact with the rear end surface 211 provided on the rear end side of the main metal member 21. The second portion 72 is a cylindrical portion provided on the rear end side of the hollow member 70, and is in contact with the front end side of the ceramic housing 60. Figure 1 In the example shown, the first front end surface 61 provided on the front end side of the ceramic housing 60 is in contact.

[0081] In the gas sensor 1, the hollow member 70 is arranged inside the outer cylinder 22, and in particular, is arranged between the main metal member 21 and the ceramic shell 60 in the axial direction. Specifically, the hollow member 70 is arranged inside the outer cylinder 22 in a state where the front end side (i.e., the first portion 71) contacts the rear end side of the main metal member 21 and the rear end side (i.e., the second portion 72) contacts the front end side of the ceramic shell 60. And the sensor element 10 axially penetrates the interior of the hollow member 70, that is, the sensor element 10 axially penetrates the interior of the first portion 71 and the second portion 72.

[0082] In the gas sensor 1, the front end side of the hollow member 70 in the axial direction is in contact with the rear end side of the main metal member 21, so that the movement of the hollow member 70 to the front end side is restricted by the main metal member 21. In addition, the ceramic shell 60 is in contact with the hollow member 70 at its front end side, that is, it is in contact with the hollow member 70 whose movement to the front end side is restricted. Therefore, in the gas sensor 1, the movement of the ceramic shell 60 to the front end side is restricted by the hollow member 70, that is, the hollow member 70 prevents the ceramic shell 60 from moving to the front end side.

[0083] The hollow member 70 is made of a material having a Young's modulus of 193 to 206 GPa, for example, a metal plate (SUS430, SUS304, low carbon steel, etc.) having a Young's modulus of 193 to 206 GPa.

[0084] Here, the inventor of the present invention believes that by making the hollow component (for example, the hollow component 70) disposed between the main metal part 21 and the ceramic shell 60 soft enough, it is possible to suppress the ceramic shell 60 that contacts the hollow component from being damaged. In addition, the inventor of the present invention believes that by making the above-mentioned hollow component (for example, the hollow component 70) have sufficient hardness, the hollow component can be used to reliably (stably) prevent the ceramic shell 60 from moving toward the front end side. Therefore, the inventor of the present invention verified through experiments (the first test described later) the mechanical properties of the material constituting the hollow component that can suppress the ceramic shell 60 from being damaged and can reliably prevent the ceramic shell 60 from moving toward the front end side. As a result, the inventor of the present invention confirmed that by making the Young's modulus of the material constituting the hollow component 193 to 206 GPa, the above-mentioned two requirements can be met. That is, the inventors of the present invention have confirmed that by setting the Young's modulus of the material constituting the hollow member to 193 to 206 GPa, it is possible to significantly suppress the ceramic housing 60 from being damaged and reliably prevent the ceramic housing 60 from moving toward the front end.

[0085] The hollow member 70 is made of a material having a Young's modulus of 193 to 206 GPa, that is, the hollow member 70 is sufficiently soft at the contact portion with the ceramic shell 60. Therefore, the hollow member 70 made of a material having a Young's modulus of 193 to 206 GPa can significantly suppress the ceramic shell 60, especially the contact portion between the ceramic shell 60 and the hollow member 70 from being damaged. That is, the hollow member 70 made of a material having a Young's modulus of 193 to 206 GPa can significantly suppress the contact portion between the ceramic shell 60 and the hollow member 70 from being damaged. For the hollow member 70, by making the contact portion (second portion 72) with the ceramic shell 60 sufficiently soft, it is possible to prevent the occurrence of a situation such as "the ceramic shell 60 is damaged due to the collision with the hollow member 70". In addition, the hollow member 70 made of a material having a Young's modulus of 193 to 206 GPa has a sufficient hardness to reliably (stably) prevent the ceramic shell 60 from moving toward the front end side. That is, the hollow member 70 is formed of a material having a Young's modulus of 193 to 206 GPa, so that the ceramic housing 60 can be reliably (stably) prevented from moving toward the front end without deformation or damage. As described above, the gas sensor 1 can suppress the risk of damage to the components (e.g., the ceramic housing 60) constituting the gas sensor 1 and prevent the ceramic housing 60 from moving toward the front end in the axial direction by the hollow member 70.

[0086] In addition, in the gas sensor 1, the airtight seal between the front end side and the rear end side of the sensor element 10 is achieved by the main metal member 21 (and the surrounding assembly member 90), and the hollow member 70 disposed between the main metal member 21 and the ceramic shell 60 does not participate in (affect) the airtight seal. That is, in the gas sensor 1, the above-mentioned airtight seal and the restriction of the movement of the ceramic shell 60 to the front end side are achieved by different components, specifically, the former is achieved by the main metal member 21 (and the surrounding assembly member 90), and the latter is achieved by the hollow member 70.

[0087] Here, in the conventional gas sensor disclosed in the above-mentioned patent document 1 (Japanese Patent Publication No. 2022-173747), the front end side component intends to take into account both the airtight sealing between the front end side and the rear end side of the sensor element and the restriction of the movement of the ceramic shell (insulator) toward the front end side. However, in order to achieve, for example, an airtight sealing between the front end side and the rear end side of the sensor element, the front end side component will move toward the front end side. Moreover, when the front end side component moves toward the front end side, the restriction of the movement of the ceramic shell toward the front end side brought by the front end side component (the fixing force for the ceramic shell) becomes insufficient, and problems such as deterioration of the vibration resistance of the gas sensor occur. That is, in the conventional gas sensor, since it is intended to take into account the above-mentioned airtight sealing and movement restriction by one component (specifically the front end side component), it is more difficult to fully achieve the latter when, for example, the former is intended to be achieved.

[0088] In view of this, in the gas sensor 1, (1) the front end and the rear end of the sensor element are hermetically sealed by the main metal member 21 (and the surrounding assembly member 90), and (2) the movement of the ceramic housing 60 toward the front end is restricted by the hollow member 70. Therefore, the gas sensor 1 does not have the problem of "it becomes difficult to restrict movement when trying to achieve the above-mentioned hermetic sealing" that exists in conventional gas sensors, and can achieve both the above-mentioned hermetic sealing and the restriction of movement.

[0089] In the hollow component 70, the first part 71 and the second part 72 may be respectively made of a material with a Young's modulus of 193 to 206 GPa. The Young's modulus of the material constituting the first part 71 may be different from the Young's modulus of the material constituting the second part 72. For example, the material constituting the first part 71 may be harder than the material constituting the second part 72. In the gas sensor 1, the ceramic shell 60 is made of ceramic, and the hollow component 70 and the main metal member 21 are made of metal, for example. Therefore, it can be considered that among the main metal member 21, the hollow component 70 and the ceramic shell 60, the ceramic shell 60 is most likely to be damaged (for example, notched) due to the impact on the gas sensor 1. Therefore, in the hollow component 70, the "part on the rear end side in contact with the ceramic shell 60 (the second part 72)" may be softer than the "part on the front end side in contact with the main metal member 21 (the first part 71)". In addition, the Young's modulus of the material constituting the first portion 71 may be the same as the Young's modulus of the material constituting the second portion 72. For example, the material constituting the first portion 71 may be the same as the material constituting the second portion 72. The hollow member 70 may be made of a material having a Young's modulus of 193 to 206 GPa. For example, the entire hollow member 70 may be made of a material having a Young's modulus of 193 to 206 GPa.

[0090] The hollow member 70 may be formed of a thin plate having a thickness of 0.3 to 0.8 mm, for example, a metal plate having a thickness of 0.3 to 0.8 mm.

[0091] Here, there is a heat source at the front end side of the gas sensor 1, so the heat released from the heat source may be transferred to the ceramic shell 60 via the hollow component 70, and then transferred to the elastomer 50 via the ceramic shell 60. In addition, when the heat is transferred to the ceramic shell 60, for example, sometimes the contact between the connector electrode 12 of the sensor element 10 and the element contact portion 31 of the terminal metal fitting 30 becomes high in temperature, resulting in contact oxidation and increased contact resistance. In addition, when the heat is transferred to the elastomer 50, the elastomer 50 may be melted. In addition, when the elastomer 50 is melted, sometimes the reference gas (reference air) in the outer cylinder 22 is contaminated, or the shock resistance of the gas sensor 1 is deteriorated. In addition, sometimes the electrode provided by the sensor element 10 (for example, a reference electrode provided so as to be in contact with the reference gas) is contaminated by the organic gas accompanying the thermal decomposition of the elastomer 50.

[0092] Therefore, the inventor of the present invention worked on the structure of the hollow component 70, and explored maintaining the strength of the hollow component 70 to prevent the ceramic shell 60 from moving toward the front end side in the axial direction and suppressing heat transfer to the ceramic shell 60 and the like. The inventor of the present invention confirmed through experiments (the second experiment described later) that by using a thin plate with a thickness of 0.3 to 0.8 mm to constitute the hollow component 70, the strength of the hollow component 70 can be maintained and heat transfer to the ceramic shell 60 and the like can be significantly suppressed. The inventor of the present invention confirmed that a thin plate with a thickness of 0.3 to 0.8 mm has sufficient strength to prevent the ceramic shell 60 from moving toward the front end side in the axial direction, and has sufficient heat capacity to suppress heat transfer to the ceramic shell 60 and the like.

[0093] Therefore, the hollow member 70 formed of a thin plate with a thickness of 0.3 to 0.8 mm can have sufficient strength to prevent the ceramic housing 60 from moving toward the front end side in the axial direction, and significantly suppress heat transfer to the ceramic housing 60, etc. Therefore, the gas sensor 1 has the following effects: the risk of damage to the components constituting the gas sensor 1 is suppressed, and the ceramic housing 60 is prevented from moving toward the front end side in the axial direction, and further, the heat resistance of the gas sensor 1 can be improved.

[0094] As described above, in the gas sensor 1, the hollow component 70 includes the first part 71 and the second part 72, and the material (component) constituting the first part 71 and the material (component) constituting the second part 72 may be different. That is, the hollow component 70 composed of a material with a Young's modulus of 193 to 206 GPa may be composed of a plurality of components. For example, the first part 71 and the second part 72 included in the hollow component 70 may be respectively composed of materials with a Young's modulus of 193 to 206 GPa and different from each other. The hollow component 70 may be composed of a plurality of components (for example, a component constituting the first part 71 and a component constituting the second part 72), and the plurality of components may be respectively composed of a material with a Young's modulus of 193 to 206 GPa. In this case, the gas sensor 1 exerts the following effect: the hollow component 70 composed of a material with a Young's modulus of 193 to 206 GPa can be easily constituted by a plurality of components.

[0095] It should be noted that in the gas sensor 1, the hollow component 70 may include components other than the components corresponding to the first portion 71 and the components corresponding to the second portion 72, for example, it may further include a third cylindrical component, a fourth cylindrical component, etc. For the gas sensor 1, it is not necessary to constitute the hollow component 70 with two components (the component corresponding to the first portion 71 and the component corresponding to the second portion 72), and the hollow component 70 may be composed of more than three components. When the hollow component 70 is composed of a plurality of components, the plurality of components may be respectively composed of a material having a Young's modulus of 193 to 206 GPa. However, the hollow component 70 may be composed of a material having a Young's modulus of 193 to 206 GPa, and it is not necessary to constitute the hollow component 70 with a plurality of components. For example, the component corresponding to the first portion 71 and the component corresponding to the second portion 72 may be integrally constituted, and the hollow component 70 may include one component. The entire hollow member 70 may be made of a material having a Young's modulus of 193 to 206 GPa.

[0096] Similar to the Young's modulus, the plate thickness of the first part 71 and the second part 72 may be different. That is, the plate thickness of the thin plate constituting the first part 71 may be different from the plate thickness of the thin plate constituting the second part 72, and the first part 71 and the second part 72 may be respectively constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm. In addition, the plate thickness of the thin plate constituting the first part 71 may be the same as the plate thickness of the thin plate constituting the second part 72, for example, the thin plate constituting the first part 71 and the thin plate constituting the second part 72 may be the same. When the hollow component 70 is constituted by a plurality of components, the plurality of components may be respectively constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm. However, the hollow component 70 may be constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm, and it is not necessary to constitute the hollow component 70 by a plurality of components. For example, the entire hollow component 70 may be constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm.

[0097] Figure 1 In the figure, the main metal fitting 21 and the hollow component 70 in contact with the rear end of the main metal fitting 21 are shown as separate components, but in the gas sensor 1, the main metal fitting 21 and the hollow component 70 can be integrally formed. For example, a component in which the open end of a thick-walled cylindrical component (first cylinder) and the open end of a thin-walled cylindrical component (second cylinder) are relatively formed integrally in a manner that the inside has a hollow space can be set as a "component in which the main metal fitting 21 and the hollow component 70 are integrally formed". The first cylinder fixes the sensor element 10 that penetrates the interior in the axial direction by means of a surrounding fitting component 90 (holding component), and corresponds to the main metal fitting 21. In addition, the second cylinder is coaxially arranged at the rear end side of the first cylinder, and contacts the front end side of the ceramic housing 60 at the rear end side in a state where the sensor element 10 penetrates the interior in the axial direction, and corresponds to the hollow component 70. The second cylinder is made of a material with a Young's modulus of 193 to 206 GPa. In addition, the second cylinder can be formed of a thin plate with a thickness of 0.3 to 0.8 mm. By forming the main metal fitting 21 and the hollow component 70 as one body, the gas sensor 1 exerts the following effect. That is, the gas sensor 1 exerts the following effect: the hollow component 70 that "suppresses the risk of damage to the components constituting the gas sensor 1 and prevents the ceramic shell 60 from moving toward the front end in the axial direction" can be easily formed together with the main metal fitting 21. In addition, the gas sensor 1 exerts the effect of being able to suppress the number of components constituting the gas sensor 1.

[0098] Figure 1In the gas sensor 1, the sensor element 10 axially penetrates the interior of the hollow component 70, and in particular, the sensor element 10 axially penetrates the interior of the hollow component 70 in a manner that does not contact the hollow component 70. That is, in the gas sensor 1, the hollow component 70 is isolated from the sensor element 10, that is, the hollow component 70 and the sensor element 10 are not in contact. Therefore, the gas sensor 1 has the following effect: it is possible to reduce the risk of interference between the hollow component 70 and the sensor element 10 and causing the element to break. For example, even if an external force is applied to the gas sensor 1 so that the hollow component 70 tilts from the axial direction, the hollow component 70 will not interfere with the sensor element 10 because it is isolated from the sensor element 10.

[0099] For example, the hollow component 70 may be configured such that the inner circumferential surface of the hollow component 70 and the sensor element 10 are spaced apart in the radial direction by a predetermined distance or more. Here, as described above, the sensor element 10 is an elongated flat plate-shaped (long strip-shaped) element. Therefore, the hollow component 70 may be configured such that, for example, the distance between the inner circumferential surface of the hollow component 70 and the sensor element 10 in at least the thickness direction of the sensor element 10 is greater than the thickness of the sensor element 10. As an example, the hollow component 70 may be configured such that the distance between the inner circumferential surface and the sensor element 10 in the thickness direction of the sensor element 10 is greater than or equal to twice the thickness of the sensor element 10. By configuring the hollow component 70 in such a manner that the inner circumferential surface and the sensor element 10 are sufficiently spaced apart in the radial direction (for example, in the thickness direction of the sensor element 10), the gas sensor 1 can more reliably prevent interference between the hollow component 70 and the sensor element 10.

[0100] <Details of the arrangement of hollow parts>

[0101] Figure 2 It is an enlarged cross-sectional view schematically showing a main part of the gas sensor 1 , and specifically, is an enlarged cross-sectional view of a main part showing an arrangement state of a hollow member 70 of the gas sensor 1 in an enlarged manner. Figure 2 In FIG. 1 , the left-right direction of the paper is the axial direction (length direction) of the gas sensor 1 (sensor element 10 ), the left side of the paper is the front end side, and the right side of the paper is the rear end side.

[0102] like Figure 2 As shown in the example, the main metal fitting 21 includes, for example: a cylindrical base portion, in which the surrounding assembly component 90 is sealed; and a cylindrical rivet portion 212, which is arranged closer to the rear end side than the base portion and presses the rear end side of the surrounding assembly component 90 in a bent state. It should be noted that Figure 2 In the figure, only the first ceramic support 91 , the compact 92 , and the second ceramic support 93 are illustrated among the first ceramic support 91 , the compact 92 , and the second ceramic support 93 constituting the surrounding fitting member 90 .

[0103] The rivet portion 212 is formed by, for example, riveting a "cylinder made of a metal plate thinner than the base extending from the rear end of the base further to the rear end side" over the entire circumference and bending radially inward. The surrounding assembly component 90 is fixed to the main metal fitting 21 by the rivet portion 212. The thickness of the rivet portion 212 is thinner than that of the base.

[0104] As described above, in the main body metal fitting 21, the rivet portion 212 is formed on the rear end side of the base, and the thickness of the base is thicker than the thickness of the rivet portion 212. Therefore, the base has a rear end surface 211 formed by the difference between the thickness of the base and the thickness of the rivet portion 212 on the rear end side thereof, and the rear end surface 211 is inclined relative to the axial direction. Figure 2 In the example shown, the rear end surface 211 is orthogonal to the axial direction, that is, parallel to the radial direction.

[0105] Furthermore, the front end side of the hollow member 70 contacts the rear end side of the main metal member 21. Figure 2 In the example shown, the first portion 71 of the hollow member 70 contacts the rear end face 211 of the main metal member 21 (base). That is, in the gas sensor 1, the main metal member 21 includes a rear end face 211 orthogonal to the axial direction on the rear end side, and the hollow member 70 (particularly the first portion 71) contacts the rear end face 211 of the main metal member 21.

[0106] Therefore, the gas sensor 1 can easily and stably position the hollow member 70 in the axial direction by using the surface (rear end surface 211) of the main metal member 21 that is orthogonal to the axial direction, and in particular, can easily and stably restrict the movement of the hollow member 70 toward the front end side. In addition, in the gas sensor 1, by easily and stably positioning the hollow member 70 in the axial direction, the ceramic housing 60 whose movement toward the front end side is restricted by the hollow member 70 can also be easily and stably positioned in the axial direction.

[0107] However, for the gas sensor 1, it is not necessary that the rear end face 211 of the main metal member 21 (base) is orthogonal to the axial direction, that is, it is not necessary that the rear end face 211 extends in the radial direction. In addition, it is not necessary that the hollow member 70 (especially the first portion 71) contacts the rear end face 211 of the main metal member 21 (base). In the gas sensor 1, the hollow member 70 can contact the rear end side of the main metal member 21, for example, it can contact the rivet portion 212.

[0108] If used Figure 1As described, the hollow component 70 contacts the main metal member 21 (particularly the rear end side of the main metal member 21) at the front end side in the axial direction, and contacts the ceramic shell 60 (particularly the front end side of the ceramic shell 60) at the rear end side in the axial direction. The hollow component 70 is restricted from moving in the axial direction by contacting the main metal member 21 at the front end side in the axial direction (i.e., the first part 71), at least restricted from moving toward the front end side. The hollow component 70 can be restricted from moving in the axial direction, at least restricted from moving toward the front end side, by being fixed to the main metal member 21. For example, the hollow component 70 can be restricted from moving in the axial direction (particularly moving toward the front end side) by being welded to the main metal member 21. The hollow component 70, which is restricted from moving toward the front end side by being fixed to the main metal member 21, can prevent the ceramic shell 60 from moving toward the front end side by contacting the ceramic shell 60 at its rear end side (i.e., the second part 72).

[0109] In addition, if Figure 2 As shown in the example, the end surface of the ceramic shell 60 on the front end side in the axial direction includes one or more (for example, multiple) surfaces inclined relative to the axial direction (for example, orthogonal to the axial direction). Figure 2 The ceramic housing 60 shown includes a first front end face 61 and a second front end face 62 on the front end side in the axial direction, and the first front end face 61 and the second front end face 62 are inclined relative to the axial direction. In particular, Figure 2 In the example shown, the first front end face 61 and the second front end face 62 are respectively orthogonal to the axial direction, that is, parallel to the radial direction.

[0110] Furthermore, the hollow member 70 is in contact with the front end of the ceramic housing 60 at its rear end. Figure 2 In the example shown, the second portion 72 of the hollow member 70 contacts the first front end face 61 of the ceramic housing 60. That is, in the gas sensor 1, the ceramic housing 60 includes a first front end face 61 orthogonal to the axial direction on the front end side, and the hollow member 70 (particularly the second portion 72) contacts the first front end face 61 of the ceramic housing 60.

[0111] Here, as described above, in the gas sensor 1, regarding the hollow component 70, its front end side (first part 71) is in contact with the main metal part 21, and the movement to the front end side is restricted by the main metal part 21. In addition, the ceramic shell 60 is in contact with the "hollow component 70 whose movement to the front end side is restricted", and in particular, the ceramic shell 60 is in contact with the rear end side (second part 72) of the hollow component 70 at the first front end face 61 orthogonal to the axial direction. Therefore, the gas sensor 1 can easily and stably achieve the positioning of the ceramic shell 60 in the axial direction by using the first front end face 61, and in particular, can easily and stably restrict the movement of the ceramic shell 60 to the front end side. In the gas sensor 1, the first front end face 61 of the ceramic shell 60 orthogonal to the axial direction is in contact with the rear end side (second part 72) of the hollow component 70 whose movement to the front end side is restricted, so that the movement of the ceramic shell 60 to the front end side can be easily and stably restricted.

[0112] It should be noted that the rear end side (second part 72) of the hollow component 70 only needs to be in contact with the ceramic shell 60, for example, it only needs to be in contact with the "surface inclined relative to the axial direction" of the front end side of the ceramic shell 60 in the axial direction. For the gas sensor 1, it is not necessary for the "surface on the front end side of the ceramic shell 60 in the axial direction" that the rear end side of the hollow component 70 contacts to be orthogonal to the axial direction. In addition, it is not necessary for the ceramic shell 60 to include a plurality of surfaces inclined relative to the axial direction on the front end side in the axial direction. The ceramic shell 60 may have one "surface inclined relative to the axial direction" on the front end side in the axial direction.

[0113] Figure 1 In the gas sensor illustrated in FIG. 1 , the ceramic housing 60 is restricted from moving toward the rear end in the axial direction by the elastic body 50 . That is, Figure 1 In the embodiment, the ceramic shell 60 is in contact with the front end side (specifically, the end face of the front end side) of the elastomer 50 at its rear end side, and is restricted from moving toward the rear end side by the elastomer 50. However, in a gas sensor according to an embodiment of the present invention, it is not necessary for the ceramic shell 60 to be restricted from moving toward the rear end side by the elastomer 50, and it is not necessary for the ceramic shell 60 to be in contact with the elastomer 50. In a gas sensor according to an embodiment of the present invention, the ceramic shell 60 may be restricted from moving toward the front end side by a hollow component (such as the hollow component 70), and the elastomer 50 may not be used to restrict the movement of the ceramic shell 60 toward the rear end side. For example, the ceramic shell 60 may be restricted from moving toward the rear end side by an outer cylinder, or by a component (such as the hollow component 70) disposed between the ceramic shell 60 and the elastomer 50. Figure 4 The movement toward the rear end side is restricted by the spacer 100 in the middle. The details of these examples are described below.

[0114] <Investigation on the shape of hollow parts>

[0115] As described above, as a hollow member for suppressing the risk of damage to the components constituting the gas sensor and preventing the ceramic housing 60 from moving toward the front end side in the axial direction, Figure 1 and Figure 2 , a hollow component 70 whose outer diameter changes in the axial direction is described. That is, the hollow component 70 described above includes: a first part 71 in contact with the rear end side of the main metal part 21, and a second part 72 in contact with the front end side of the ceramic shell 60, and the outer diameter of the first part 71 is different from the outer diameter of the second part 72. However, for the hollow component possessed by the gas sensor involved in one embodiment of the present invention, it is not necessary for the outer diameter to change in the axial direction. Below, as a hollow component for suppressing the risk of damage to the components constituting the gas sensor and preventing the ceramic shell 60 from moving axially toward the front end side, a hollow component 70A whose outer diameter is constant in the axial direction (that is, the outer diameter does not change) is described.

[0116] Figure 3 1 is a schematic cross-sectional view schematically showing an example of a main structure of a gas sensor 1A according to Modification 1. FIG. Figure 3 In the figure, the left-right direction of the paper is the axial direction (length direction) of the gas sensor 1A, the left side of the paper is the front end side, and the right side of the paper is the rear end side. Figure 3 The gas sensor 1A illustrated in FIG. 1 includes a hollow member 70A to suppress the risk of damage to the members constituting the gas sensor 1A and to prevent the ceramic housing 60 from moving toward the front end side in the axial direction. Figure 3 The gas sensor 1A illustrated in the example and the use Figure 1 , Figure 2 Compared with the gas sensor 1 described above, the gas sensor 1A is the same except for the following two points. First, the gas sensor 1A has a hollow member 70A instead of the hollow member 70. Second, in the gas sensor 1A, the movement of the ceramic shell 60 to the rear end side is restricted by the outer cylinder 22A instead of the elastic body 50. Except for these two points, the gas sensor 1A is the same as the gas sensor 1, and therefore, in the following description, detailed description of the configuration other than the hollow member 70A and the outer cylinder 22A is omitted.

[0117] (Hollow parts)

[0118] The hollow member 70A is a hollow member having a cylindrical (columnar) appearance, and in particular, is a hollow member having a cylindrical appearance with a constant outer diameter in the axial direction. Figure 3 The hollow member 70A illustrated in FIG. 1 is configured by, for example, folding one end (the rear end in the illustrated example) of a cylindrical member radially inward over the entire circumference. Figure 3The hollow component 70A illustrated in the figure is a hollow component whose two rear end portions are respectively formed into a roughly U-shape at the cross section parallel to the axis AL and in contact with the axis AL, and the outer diameter of the hollow component 70A is constant in the axial direction. That is, the hollow component 70A includes: a first portion 71A arranged at the front end side in the axial direction, and a second portion 72A arranged axially closer to the rear end side than the first portion 71A and having the same outer diameter as the first portion 71A. The first portion 71A is a cylindrical portion of the hollow component 70A provided at the front end side, in contact with the rear end side of the main metal component 21, and Figure 3 In the example shown, it contacts the rear end surface 211 of the main metal part 21 arranged on the rear end side. The second part 72A is the part on the rear end side of the hollow component 70A, specifically, the part extending from the first part 71A to the rear end side. The second part 72A is parallel to the axis AL and in contact with the axis AL, and the two rear ends are respectively configured to be roughly U-shaped. The second part 72A contacts the ceramic shell 60 at its rear end, in particular, the front end side of the ceramic shell 60. The second part 72A is formed by, for example, folding the rear end side of the "cylindrical component extending further to the rear end side from the rear end portion of the first part 71A" radially inwardly in the entire circumference. In addition, the first part 71A and the second part 72A have a cylindrical (columnar) appearance with equal outer diameters. However, for the hollow component involved in one embodiment of the present invention, it is not necessary for the outer diameter of the first part 71A and the outer diameter of the second part 72A to be equal, and the outer diameters of the two may be different.

[0119] In the gas sensor 1A, the hollow member 70A is arranged between the main body metal fitting 21 and the ceramic shell 60 in the axial direction. Specifically, the hollow member 70A is arranged inside the outer cylinder 22A in a state where the front end side (i.e., the first portion 71A) contacts the rear end side of the main body metal fitting 21, and the rear end side (i.e., the second portion 72A) contacts the front end side of the ceramic shell 60. And the sensor element 10 axially penetrates the inside of the hollow member 70A, that is, the sensor element 10 axially penetrates the inside of the first portion 71A and the second portion 72A.

[0120] That is, in the gas sensor 1A, the front end side of the hollow member 70A in the axial direction is in contact with the rear end side of the main metal member 21, and therefore, the movement of the hollow member 70A to the front end side is restricted by the main metal member 21. Furthermore, the ceramic housing 60 is in contact with the hollow member 70A at its front end side, that is, it is in contact with the hollow member 70A whose movement to the front end side is restricted. Therefore, in the gas sensor 1A, the movement of the ceramic housing 60 to the front end side is restricted by the hollow member 70A, that is, the hollow member 70A prevents the ceramic housing 60 from moving to the front end side.

[0121] The hollow component 70A is made of a material with a Young's modulus of 193 to 206 GPa, for example, a metal plate with a Young's modulus of 193 to 206 GPa. Therefore, the hollow component 70A made of a material with a Young's modulus of 193 to 206 GPa can significantly suppress the ceramic shell 60, especially the contact portion between the ceramic shell 60 and the hollow component 70A from being damaged. That is, the hollow component 70A made of a material with a Young's modulus of 193 to 206 GPa can significantly suppress the contact portion between the ceramic shell 60 and the hollow component 70A from being damaged. With respect to the hollow component 70A, by making the contact portion (the second portion 72A) with the ceramic shell 60 sufficiently soft, it is possible to prevent a situation such as "the ceramic shell 60 is damaged due to collision with the hollow component 70A" from occurring. In addition, the hollow member 70A made of a material having a Young's modulus of 193 to 206 GPa has a sufficient hardness to reliably (stably) prevent the ceramic shell 60 from moving toward the front end side. That is, the hollow member 70A is made of a material having a Young's modulus of 193 to 206 GPa, and can reliably (stably) prevent the ceramic shell 60 from moving toward the front end side without deformation or damage. As described above, the gas sensor 1A can suppress the risk of damage to the components (e.g., the ceramic shell 60) constituting the gas sensor 1A by the hollow member 70A, and prevent the ceramic shell 60 from moving toward the front end side in the axial direction.

[0122] In addition, in the gas sensor 1A, (1) the front end and the rear end of the sensor element are hermetically sealed by the main metal member 21 (and the surrounding assembly member 90), and (2) the movement of the ceramic housing 60 toward the front end is restricted by the hollow member 70A. Therefore, the gas sensor 1A does not have the problem of "it becomes difficult to restrict movement when trying to achieve the above-mentioned hermetic sealing" that exists in conventional gas sensors, and can achieve both the above-mentioned hermetic sealing and the restriction of movement.

[0123] As described above, the hollow component 70A contacts the main metal fitting 21 (particularly the rear end side of the main metal fitting 21) at the front end side in the axial direction, and contacts the ceramic shell 60 (particularly the front end side of the ceramic shell 60) at the rear end side in the axial direction. The hollow component 70A is restricted from moving in the axial direction, at least to the front end side, by contacting the main metal fitting 21 at the front end side in the axial direction (i.e., the first portion 71A). The hollow component 70A can be restricted from moving in the axial direction, at least to the front end side, by being fixed to the main metal fitting 21. For example, by being welded to the main metal fitting 21, the axial movement (particularly to the front end side) can be restricted. The hollow component 70A, whose movement to the front end side is restricted by being fixed to the main metal fitting 21, contacts the ceramic shell 60 at its rear end side (i.e., the second portion 72A), thereby preventing the ceramic shell 60 from moving to the front end side.

[0124] The hollow component 70A, like the hollow component 70, can be formed of a thin plate with a thickness of 0.3 to 0.8 mm, for example, a metal plate with a thickness of 0.3 to 0.8 mm. The hollow component 70A formed of a thin plate with a thickness of 0.3 to 0.8 mm can have sufficient strength to prevent the ceramic shell 60 from moving toward the front end side in the axial direction, and significantly suppress heat transfer to the ceramic shell 60, etc. Therefore, the gas sensor 1A exerts the following effects: it can suppress the risk of damage to the components constituting the gas sensor 1A, and prevent the ceramic shell 60 from moving toward the front end side in the axial direction, thereby improving the heat resistance of the gas sensor 1A.

[0125] In the gas sensor 1A, the material (component) constituting the first part 71A and the material (component) constituting the second part 72A may be different. In the hollow component 70A, the first part 71A and the second part 72A may be respectively constituted by a material having a Young's modulus of 193 to 206 GPa. The Young's modulus of the material constituting the first part 71A may be different from the Young's modulus of the material constituting the second part 72A. For example, the material constituting the first part 71A may be harder than the material constituting the second part 72A. That is, the hollow component 70A composed of a material having a Young's modulus of 193 to 206 GPa may be composed of a plurality of components. For example, the first part 71A and the second part 72A included in the hollow component 70A may be respectively constituted by materials having a Young's modulus of 193 to 206 GPa and being different from each other. The hollow member 70A may be composed of a plurality of members (e.g., a member constituting the first portion 71A and a member constituting the second portion 72A) each of which is made of a material having a Young's modulus of 193 to 206 GPa. In this case, the gas sensor 1A has the following effect: the hollow member 70A made of a material having a Young's modulus of 193 to 206 GPa can be easily constituted by a plurality of members. The gas sensor 1A can easily constitute the hollow member 70A made of a material having a Young's modulus of 193 to 206 GPa by a plurality of members including, for example, a member corresponding to the first portion 71A and a member corresponding to the second portion 72A.

[0126] It should be noted that in the gas sensor 1A, the hollow component 70A may include components other than the components corresponding to the first portion 71A and the components corresponding to the second portion 72A. The hollow component 70A may include, for example, a third cylindrical component, a fourth cylindrical component, etc., in addition to the components corresponding to the first portion 71A and the components corresponding to the second portion 72A. For the gas sensor 1A, it is not necessary to constitute the hollow component 70A with two components (the component corresponding to the first portion 71A and the component corresponding to the second portion 72A), and the hollow component 70A may be composed of three or more components. When the hollow component 70A is composed of a plurality of components, the plurality of components may be respectively composed of a material having a Young's modulus of 193 to 206 GPa. However, the hollow component 70A may be composed of a material having a Young's modulus of 193 to 206 GPa, and it is not necessary to constitute the hollow component 70A with a plurality of components. For example, the member corresponding to the first portion 71A and the member corresponding to the second portion 72A may be integrally formed, and the hollow member 70A may include a single member. The hollow member 70A may be entirely formed of a material having a Young's modulus of 193 to 206 GPa.

[0127] Similar to the Young's modulus, the plate thickness of the first part 71A and the second part 72A may be different. That is, the plate thickness of the thin plate constituting the first part 71A may be different from the plate thickness of the thin plate constituting the second part 72A, and the first part 71A and the second part 72A may be respectively constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm. In addition, the plate thickness of the thin plate constituting the first part 71A may be the same as the plate thickness of the thin plate constituting the second part 72A, for example, the thin plate constituting the first part 71A and the thin plate constituting the second part 72A may be the same. In the case where the hollow component 70A is constituted by a plurality of components, the plurality of components may be respectively constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm. However, the hollow component 70A may be constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm, and it is not necessary to constitute the hollow component 70A with a plurality of components. For example, the entire hollow component 70A may be constituted by a thin plate with a plate thickness of 0.3 to 0.8 mm.

[0128] Figure 3 In the figure, the main metal fitting 21 and the hollow component 70A in contact with the rear end of the main metal fitting 21 are shown as separate components, but in the gas sensor 1A, the main metal fitting 21 and the hollow component 70A can be integrally formed. By integrally forming the main metal fitting 21 and the hollow component 70A, the gas sensor 1A exerts the following effect. That is, the gas sensor 1A exerts the following effect: the hollow component 70A that "suppresses the risk of damage to the components constituting the gas sensor 1A and prevents the ceramic shell 60 from moving toward the front end side in the axial direction" can be easily formed together with the main metal fitting 21. In addition, the gas sensor 1A exerts the effect of being able to suppress the number of components constituting the gas sensor 1A.

[0129] Similar to the main metal fitting 21 in the gas sensor 1, in the gas sensor 1A, the main metal fitting 21 includes a rear end face 211 inclined relative to the axial direction, for example, including a rear end face 211 orthogonal to the axial direction. Furthermore, the hollow member 70A contacts the rear end side of the main metal fitting 21 at its front end side. Figure 3 In the example shown, the first portion 71A of the hollow member 70A is in contact with the rear end surface 211 of the main body metal member 21 (particularly, the base of the main body metal member 21).

[0130] Therefore, the gas sensor 1A can easily and stably position the hollow member 70A in the axial direction by using the surface (rear end surface 211) of the main metal member 21 that is orthogonal to the axial direction, and can particularly easily and stably restrict the movement of the hollow member 70A toward the front end side. In addition, in the gas sensor 1A, by easily and stably positioning the hollow member 70A in the axial direction, the ceramic housing 60 whose movement toward the front end side is restricted by the hollow member 70A can also be easily and stably positioned in the axial direction.

[0131] In addition, as described above, the front end side of the ceramic shell 60 in the axial direction includes a first front end face 61 and a second front end face 62, and the first front end face 61 and the second front end face 62 are respectively inclined relative to the axial direction, for example, orthogonal to the axial direction. In addition, the hollow member 70A contacts the front end side of the ceramic shell 60 at its rear end side. Figure 3 In the example shown, the second portion 72A of the hollow component 70A contacts the first front end face 61 of the ceramic shell 60. In addition, regarding the hollow component 70A, its front end side (first portion 71A) contacts the main metal member 21, and movement toward the front end side is restricted by the main metal member 21. Therefore, the gas sensor 1A can easily and stably achieve axial positioning of the ceramic shell 60 by utilizing the first front end face 61, and in particular, can easily and stably restrict movement of the ceramic shell 60 toward the front end side. In the gas sensor 1A, the first front end face 61 of the ceramic shell 60 that is orthogonal to the axial direction contacts the rear end side (second portion 72A) of the hollow component 70A whose movement toward the front end side is restricted, so that movement of the ceramic shell 60 toward the front end side can be easily and stably restricted.

[0132] Figure 3 In the gas sensor 1A, the sensor element 10 axially penetrates the interior of the hollow component 70A, and in particular, the sensor element 10 axially penetrates the interior of the hollow component 70A in a manner that does not contact the hollow component 70A. That is, in the gas sensor 1A, the hollow component 70A is separated from the sensor element 10, that is, the hollow component 70A and the sensor element 10 are not in contact. Therefore, the gas sensor 1A has the following effect: it is possible to reduce the risk of interference between the hollow component 70A and the sensor element 10 and causing the element to break. For example, even if an external force is applied to the gas sensor 1A so that the hollow component 70A tilts from the axial direction, the hollow component 70A will not interfere with the sensor element 10 because it is separated from the sensor element 10.

[0133] For example, the hollow member 70A may be configured such that the inner circumferential surface of the hollow member 70A and the sensor element 10 are spaced apart in the radial direction by a predetermined distance or more. The hollow member 70A may be configured such that, for example, the distance between the inner circumferential surface of the hollow member 70A and the sensor element 10 in at least the thickness direction of the sensor element 10 is equal to or greater than the thickness of the sensor element 10. As an example, the hollow member 70A may be configured such that the distance between the inner circumferential surface and the sensor element 10 in the thickness direction of the sensor element 10 is equal to or greater than twice the thickness of the sensor element 10. By configuring the hollow member 70A so that the inner circumferential surface and the sensor element 10 are sufficiently spaced apart in the radial direction (for example, in the thickness direction of the sensor element 10), the gas sensor 1A can more reliably prevent interference between the hollow member 70A and the sensor element 10.

[0134] (outer cylinder)

[0135] As described above, in the gas sensor 1A, the movement of the ceramic case 60 toward the rear end is restricted by the outer cylinder 22A instead of the elastic body 50. Therefore, in the gas sensor 1A, the ceramic case 60 does not need to be in contact with the elastic body 50. Figure 3 In the gas sensor 1A illustrated in FIG. 1 , the ceramic housing 60 is isolated from the elastic body 50, that is, the ceramic housing 60 and the elastic body 50 are not in contact. By isolating the elastic body 50 from the ceramic housing 60 disposed at the front end side of the elastic body 50 in the axial direction, the gas sensor 1A exerts the following effect. That is, the gas sensor 1A exerts the following effect: it is possible to prevent the heat released from the heat source located at the front end side of the gas sensor 1A from being transferred to the elastic body 50 via the ceramic housing 60, thereby preventing the elastic body 50 from being melted due to the heat.

[0136] In the gas sensor 1A, the inner peripheral surface of the outer cylinder 22A that accommodates the ceramic housing 60 includes a portion (locking portion 222) inclined from the axial direction on the rear end side. Figure 3 In the example shown, the locking portion 222 is perpendicular (substantially perpendicular) to the axial direction. Figure 3 The outer cylinder 22A illustrated in the figure has a portion (reduced diameter portion) at the rear end side (particularly at the rear end side closer to the front end side than the end face at the front end side of the elastic body 50) where the outer diameter becomes smaller. Furthermore, at the reduced diameter portion, the inner circumferential surface of the outer cylinder 22A is inclined relative to the axial direction. In the example shown in the figure, at the reduced diameter portion, the inner circumferential surface of the outer cylinder 22A is orthogonal (substantially orthogonal) to the axial direction. That is, at the reduced diameter portion, the inner circumferential surface of the outer cylinder 22A is inclined relative to the axial direction, and the portion inclined relative to the axial direction is the locking portion 222. Furthermore, at the locking portion 222, the ceramic shell 60 contacts the inner circumferential surface of the outer cylinder 22A, that is, the ceramic shell 60 contacts the locking portion 222 at the inner circumferential surface of the outer cylinder 22A. The ceramic shell 60 contacts the locking portion 222 at the inner circumferential surface of the outer cylinder 22A at the rear end side in the axial direction, thereby being restricted from moving toward the rear end side in the axial direction, that is, the outer cylinder 22A restricts the ceramic shell 60 from moving toward the rear end side. Therefore, the gas sensor 1A can prevent the ceramic case 60 from moving toward the rear end side in the axial direction without causing the ceramic case 60 and the elastic body 50 to come into contact with each other.

[0137] In particular, as described above, in the retaining portion 222, the inner circumferential surface of the outer cylinder 22A is inclined from the axial direction, for example, orthogonal (substantially orthogonal) to the axial direction. Therefore, the gas sensor 1A can easily and stably achieve the axial positioning of the ceramic shell 60 by utilizing the retaining portion 222, and in particular can easily and stably limit the movement of the ceramic shell 60 toward the rear end side. For example, in the gas sensor 1A, the movement of the ceramic shell 60 toward the rear end side can be easily and stably limited by the contact between the end face on the rear end side of the ceramic shell 60 (for example, the end face on the rear end side orthogonal to the axial direction) and the retaining portion 222 orthogonal to the axial direction.

[0138] However, it is not necessary that the inner circumferential surface of the outer cylinder 22A is orthogonal (substantially orthogonal) to the axial direction at the locking portion 222, and the inner circumferential surface of the outer cylinder 22A may be inclined relative to the axial direction at the locking portion 222. In addition, it is not necessary that the end surface on the rear end side of the ceramic shell 60 (i.e., the end surface on the rear end side of the ceramic shell 60 that contacts the inner circumferential surface of the outer cylinder 22A at the locking portion 222) is orthogonal to the axial direction, and the end surface on the rear end side may be inclined relative to the axial direction.

[0139] The outer cylinder 22A is different from the outer cylinder 22 in that: (1) the above-mentioned reduced diameter portion is formed on the rear end side (particularly on the rear end side closer to the front end side than the end face on the front end side of the elastic body 50); and (2) a hollow member 70A is housed instead of the hollow member 70. For example, the outer cylinder 22A is a cylindrical member extending in the axial direction, and as an example, it is a cylindrical member made of metal. The outer cylinder 22A is mounted on the rear end side of the main metal member 21, and houses the rear end of the sensor element 10, the hollow member 70A, and the ceramic housing 60 (terminal metal member 30) therein, and the open end on the rear end side thereof is closed by the elastic body 50.

[0140] <Consideration of the structure for restricting the movement of the ceramic housing toward the rear end>

[0141] The above describes the gas sensor 1 in which the ceramic shell 60 is restricted from moving toward the rear end by the elastic body 50, and the gas sensor 1A in which the ceramic shell 60 is restricted from moving toward the rear end by the outer cylinder 22A. However, in a gas sensor according to one embodiment of the present invention, the ceramic shell 60 is restricted from moving toward the front end by a hollow member (e.g., hollow member 70, 70A), and the method for restricting the movement of the ceramic shell 60 toward the rear end is not particularly limited. Figure 4 , a gas sensor 1B in which movement of the ceramic housing 60 to the rear end side is restricted by components other than the elastic body 50 and the outer cylinder 22A will be described.

[0142] Figure 4 1 is a schematic cross-sectional view schematically showing an example of a main structure of a gas sensor 1B according to Modification 2. Figure 4In the figure, the left-right direction of the paper is the axial direction (length direction) of the gas sensor 1B, the left side of the paper is the front end side, and the right side of the paper is the rear end side. Figure 4 The gas sensor 1B illustrated in the figure has a hollow component 70A in the same manner as the gas sensor 1A to suppress the risk of damage to the components constituting the gas sensor 1B and to prevent the ceramic shell 60 from moving toward the front end side in the axial direction. Specifically, the gas sensor 1B has a sensor element 10, a main metal fitting 21, a terminal metal fitting 30, a ceramic shell 60, a hollow component 70A, and an elastic body 50 in the same manner as the gas sensor 1A, and also has an outer cylinder 22B that is the same as the outer cylinders 22 and 22A described above. However, in addition to the above-mentioned components that are the same as the gas sensor 1 or the gas sensor 1A, the gas sensor 1B also has a spacer 100. Furthermore, in the gas sensor 1B, the movement of the ceramic shell 60 toward the rear end side is restricted by the spacer 100 disposed between the ceramic shell 60 and the elastic body 50 rather than by the elastic body 50 and the outer cylinder 22A. The gas sensor 1B is similar to the gas sensors 1 and 1A described above except for this point, and therefore, in the following description, detailed description of the configuration other than the outer tube 22B and the spacer 100 will be omitted.

[0143] (outer cylinder)

[0144] The difference between the outer cylinder 22B and the outer cylinders 22 and 22A is that "a spacer 100 is stored inside". In addition, the difference between the outer cylinder 22B and the outer cylinder 22 is that a hollow member 70A is stored instead of the hollow member 70. In addition, the difference between the outer cylinder 22B and the outer cylinder 22A is that the inner peripheral surface is isolated from the ceramic shell 60 (not in contact with the ceramic shell 60). In other respects, the outer cylinder 22B is the same as the outer cylinders 22 and 22A. For example, the outer cylinder 22B is a tubular (for example, cylindrical) component that stores the rear end of the sensor element 10, the hollow member 70A, the ceramic shell 60 (the terminal metal fitting 30), and the spacer 100 inside, and for example, it is a metal tubular component. The outer cylinder 22B is mounted on the rear end side of the main metal fitting 21, and the open end on the rear end side is closed by the elastic body 50.

[0145] (Spacer)

[0146] The spacer 100 is an example of the "spacer" of the present invention. The spacer 100 is arranged between the ceramic shell 60 and the elastomer 50 in the axial direction of the gas sensor 1B (sensor element 10). That is, the spacer 100 is sandwiched by the ceramic shell 60 and the elastomer 50 inside the cylindrical body 20 (outer cylinder 22B) (between the ceramic shell 60 and the elastomer 50). Specifically, the spacer 100 contacts the rear end side of the ceramic shell 60 on the front end side, and contacts the front end side of the elastomer 50 on the rear end side. Therefore, in the gas sensor 1B, the spacer 100 is restricted from moving toward the rear end side by the elastomer 50, and the ceramic shell 60 is restricted from moving toward the rear end side by the spacer 100. Therefore, the gas sensor 1B can prevent the ceramic shell 60 from moving toward the front end side by the hollow component 70A, and can also prevent the ceramic shell 60 from moving toward the rear end side by the spacer 100.

[0147] In addition, in the gas sensor 1B, the elastic body 50 is arranged to be closer to the rear end side than the ceramic housing 60 and the spacer 100 in the axial direction. Therefore, the gas sensor 1B exerts the following effect: the ceramic housing 60 and the spacer 100 can effectively suppress the heat released from the heat source located on the front end side of the gas sensor 1B from being transferred to the elastic body 50. It should be noted that the spacer 100 arranged to be closer to the front end side than the elastic body 50 in the axial direction is preferably composed of a heat-resistant material. By forming the spacer 100 with a heat-resistant material, it is possible to prevent the spacer 100 arranged to be closer to the front end side than the elastic body 50 in the axial direction from being melted due to the heat released from the heat source.

[0148] exist Figure 4 The wire 40 is inserted into the spacer 100 illustrated in the figure. In the gas sensor 1B, the wire 40 is inserted into a through hole (not shown) continuously provided in, for example, the elastomer 50 and the spacer 100. Specifically, the wire 40 and the terminal metal fitting 30 (particularly, a wire holding portion for crimping and holding the wire 40) are accommodated inside the spacer 100. For example, a through hole extending in the axial direction is formed inside the spacer 100. In the interior of the spacer 100, as in the interior of the elastomer 50, a plurality of through holes extending in the axial direction may be formed. The wire 40 and the wire holding portion of the terminal metal fitting 30 are accommodated (inserted) in the through hole formed inside the spacer 100. For example, each of the plurality of wires 40 and the wire holding portion of the terminal metal fitting 30 is accommodated (inserted) in a respective through hole of the plurality of through holes formed inside the spacer 100. Figure 41B shows an example in which two through holes are formed inside the spacer 100 and two wires 40 and two wire holding portions of the terminal metal fittings 30 are respectively accommodated in the two through holes. In the gas sensor 1B, the wires 40 and the wire holding portions of the terminal metal fittings 30 are electrically connected inside the spacer 100.

[0149] As described above, the spacer 100 is made of, for example, a heat-resistant material and is disposed between the elastomer 50 and the ceramic shell 60. By placing the spacer 100 between the elastomer 50 and the ceramic shell 60, it is possible to prevent the elastomer 50 from overheating when the gas sensor 1B is in use. Therefore, from the viewpoint of suppressing heat transfer toward the elastomer 50, it is preferred that the thermal conductivity of the spacer 100 is low. However, although the temperature rise of the elastomer 50 is suppressed by the spacer 100, the spacer 100 becomes high temperature, and therefore, the spacer 100 itself needs to have sufficient heat resistance. Therefore, by forming the spacer 100 from a heat-resistant material, it is possible to suppress the above-mentioned heat transfer from the heat source to the elastomer 50, and prevent the spacer 100 itself from melting due to the heat released from the heat source. For example, the spacer 100 can be made of ceramic. Ceramics have excellent heat resistance and generally have a higher melting point than resin. However, it is not essential for the gas sensor 1B to form the spacer 100 using ceramics, and the gas sensor 1B can appropriately use a heat-resistant raw material as the material of the spacer 100 .

[0150] It should be explained that Figure 4 , an example in which the spacer 100 is provided as one component is shown, however, the spacer 100 may be provided with a plurality of components (constituent components). For example, the spacer 100 may include: a spacer front end side portion arranged at the front end side in the axial direction, and a spacer rear end side portion arranged at the rear end side. That is, the spacer 100 may be provided with a multi-stage structure (for example, a two-stage structure) including a spacer front end side portion and a spacer rear end side portion.

[0151] When the spacer 100 is used to suppress the temperature rise of the elastic body 50 when the gas sensor 1B is used, the spacer front end side portion and the spacer rear end side portion can be respectively configured as follows. That is, as the material of the spacer front end side portion arranged at the front end side in the axial direction, ceramic with a higher melting point than resin is selected from the point of having better heat resistance than the spacer rear end side portion. Ceramics with a thermal conductivity of 32 W / m·K or less, which are both excellent in heat resistance and heat insulation, are preferred, and alumina (thermal conductivity: 32 W / m·K) or steatite (thermal conductivity: 2 W / m·K) is more preferred. On the other hand, as the material of the spacer rear end side portion in contact with the elastic body 50, resin is selected from the point of having low thermal conductivity compared with ceramics. The resin used for the spacer rear end side portion is preferably PTFE (polytetrafluoroethylene, melting point 327°C) or PFA (perfluoroalkoxyalkane, melting point 310°C), both of which are fluororesins. These resins have low thermal conductivity and higher heat resistance than the rubber elastic body 50. For example, PTFE has a thermal conductivity of 0.2 W / m·K and a continuous maximum use temperature (the maximum temperature when used continuously at the maximum temperature) of 260°C.

[0152] [feature]

[0153] As described above, the gas sensor (1, 1A, 1B) involved in this embodiment includes: a sensor element 10, a main metal fitting 21, an outer cylinder (22, 22A, 22B), a terminal metal fitting 30, a ceramic shell 60, an elastic body 50, and a hollow component (70, 70A). The sensor element 10 extends in the axial direction and has a connector electrode 12 on the rear end side. The main metal fitting 21 is cylindrical, and the sensor element 10 passes through the interior thereof in the axial direction. The outer cylinder is a cylindrical component extending in the axial direction and is assembled on the outer peripheral surface of the rear end side of the main metal fitting 21. The terminal metal fitting 30 extends in the axial direction and has an element contact portion 31 on the front end side, and the element contact portion 31 is electrically connected to the connector electrode 12 of the sensor element 10. The ceramic shell 60 is arranged inside the outer cylinder to accommodate the connector electrode 12 of the sensor element 10 and the element contact portion 31 of the terminal metal fitting 30. The elastic body 50 is arranged to close the open end on the rear end side of the outer cylinder. The hollow member is arranged inside the outer cylinder, and the sensor element 10 penetrates the inside thereof in the axial direction. The front end side of the hollow member in the axial direction contacts the rear end side of the main metal member 21, and the rear end side in the axial direction contacts the front end side of the ceramic housing 60. The hollow member is made of a material having a Young's modulus of 193 to 206 GPa.

[0154] Regarding this structure, in the gas sensor of this embodiment, the front end side of the hollow component (70, 70A) in the axial direction is in contact with the rear end side of the main metal component 21, that is, the movement toward the front end side is restricted by the main metal component 21. In addition, the ceramic shell 60 is in contact with the hollow component whose movement toward the front end side is restricted. Therefore, in the gas sensor of this embodiment, the movement of the ceramic shell 60 toward the front end side is restricted by the hollow component, that is, the hollow component prevents the ceramic shell 60 from moving toward the front end side.

[0155] In the gas sensor of the present embodiment, the Young's modulus of the material constituting the hollow member ( 70 , 70A) is 193 to 206 GPa.

[0156] In the first test described later, the inventors of the present invention confirmed that by setting the Young's modulus of the material constituting the hollow component to 193 to 206 GPa, the following two effects can be achieved. First, the inventors of the present invention confirmed that by setting the Young's modulus of the material constituting the hollow component to 193 to 206 GPa, the ceramic shell 60 in contact with the hollow component can be significantly suppressed from being damaged. Second, the inventors of the present invention confirmed that by setting the Young's modulus of the material constituting the hollow component to 193 to 206 GPa, the hollow component can reliably (stably) prevent the ceramic shell 60 from moving toward the front end side.

[0157] Therefore, the hollow member made of a material having a Young's modulus of 193 to 206 GPa can significantly suppress the ceramic housing 60 from being damaged, and can reliably prevent the ceramic housing 60 from moving toward the front end side.

[0158] Therefore, the gas sensor of the present embodiment has the effect of preventing the ceramic case 60 from moving toward the front end side in the axial direction while suppressing the risk of damage to the components constituting the gas sensor.

[0159] [Modifications]

[0160] The embodiments of the present invention have been described above. However, the description of the aforementioned embodiments is merely an example of the present invention in all aspects. Various improvements and modifications may be made to the aforementioned embodiments. Regarding the various components of the aforementioned embodiments, the components may be appropriately omitted, replaced, and added. In addition, the shape and size of the various components of the aforementioned embodiments may be appropriately changed according to the embodiments. For example, the following changes may be made. It should be noted that, hereinafter, the same symbols are used for the same components as the aforementioned embodiments, and the description of the same points as the aforementioned embodiments is appropriately omitted. The following modifications may be appropriately combined.

[0161] <About the shape of the ceramic case>

[0162] As described above, the end surface of the front end side of the ceramic housing 60 in the axial direction includes a plurality of surfaces (for example, including Figure 2 However, in a gas sensor according to one embodiment of the present invention, the end face of the front end side of the ceramic shell 60 in the axial direction may include one or more faces inclined relative to the axial direction (for example, perpendicular to the axial direction). For example, the entire end face of the front end side of the ceramic shell 60 may be perpendicular to the axial direction, that is, the entire end face of the front end side of the ceramic shell 60 may be parallel to the radial direction. The hollow component of one embodiment of the present invention (for example, the hollow component 70, 70A) may be in contact with any one of the one or more "faces inclined relative to the axial direction (for example, perpendicular to the axial direction)" included in the end face of the front end side of the ceramic shell 60 at the rear end side in the axial direction.

[0163] <About the appearance of hollow parts>

[0164] As described above, as a hollow component (e.g., hollow component 70, 70A) of one embodiment of the present invention, a hollow component having a cylindrical (columnar) appearance is described. However, it is not necessary for the hollow component of one embodiment of the present invention to have a cylindrical appearance. The hollow component of one embodiment of the present invention may have, for example, a triangular cylindrical appearance, or may have a square cylindrical appearance (quadrangular cylindrical, pentagonal cylindrical, hexagonal cylindrical, etc.). The hollow component of one embodiment of the present invention is, for example, a hollow component that is cylindrical in shape as a whole.

[0165] [Example]

[0166] <First Test>

[0167] In order to verify the effect of the present invention (especially the impact resistance of the gas sensor), the inventors of the present invention manufactured gas sensors of the following gears (Examples) 1 to 6 and conducted impact tests on multiple gas sensors of each gear. However, the present invention is not limited to the following gears (Examples).

[0168] Table 1

[0169]

[0170] The gas sensors for gear positions 1 to 5 are respectively Figure 1 The gas sensors of the configuration (components) illustrated in the example are gas sensors in which a hollow component (70) is arranged between a main metal member (21) and a ceramic housing (60). However, in the gas sensors of the gears 1 to 5, the Young's modulus of the material (e.g., metal plate) constituting the hollow component is different from each other.

[0171] That is, the gas sensors of the gears 1 to 5 are respectively provided with a hollow component inside the outer tube (22), the front end side of which is in contact with the rear end side of the main metal part, and the rear end side of which is in contact with the front end side of the ceramic shell. Furthermore, in the gas sensors of the gears 1 to 5, the sensor element (10) respectively penetrates the interior of the above-mentioned hollow component in the axial direction. The common point of the gas sensors of the gears 1 to 5 is that they are provided with the hollow component, but the Young's modulus of the material constituting the hollow component is different from each other in the gas sensors of the gears 1 to 5. Specifically, in the gas sensor of the gear 1, the hollow component is composed of a metal plate with "Young's modulus of 193 [GPa] (the unit [GPa] is omitted hereinafter) and a plate thickness of 0.3 [mm] (the unit [mm] is omitted hereinafter)". In the gas sensor of the gear position 2, the hollow part is composed of a metal plate with a Young's modulus of 200 and a thickness of 0.3. In addition, in the gas sensor of the gear position 3, the hollow part is composed of a metal plate with a Young's modulus of 206 and a thickness of 0.3. In the gas sensor of the gear position 4, the hollow part is composed of a metal plate with a Young's modulus of 72 and a thickness of 0.3. In addition, in the gas sensor of the gear position 5, the hollow part is composed of a metal plate with a Young's modulus of 360 and a thickness of 0.3.

[0172] In contrast, the gas sensor of the gear position 6 is a conventional gas sensor as disclosed in the above-mentioned patent document 1 (Japanese Patent Publication No. 2022-173747), that is, it is a gas sensor in which no hollow part is arranged between the main metal part and the ceramic shell. Specifically, the gas sensor of the gear position 6 comprises: a front end side part (made of ceramic) extending to a position closer to the rear end side than the main metal part surrounding the periphery of the sensor element. In addition, in the gas sensor of the gear position 6, the isolating member is clamped by the front end side part and the rubber cap (elastomer), thereby preventing the isolating member from moving in the axial direction of the gas sensor.

[0173] In order to compare the impact resistance of gas sensors, the inventors of the present invention conducted an impact test in which the gas sensors of each of the gears 1 to 6 were dropped from a predetermined height (drop height). That is, the impact test was conducted as follows: the drop height was set to 1.0 [m] (the unit [m] is omitted below), 1.2, 1.4, 1.6, 1.8, and 2.0, and the gas sensors of each of the gears 1 to 6 were dropped from each drop height. In addition, the inventors of the present invention confirmed whether the gas sensors after the impact test had problems such as poor conduction (e.g., contact deviation between the connector electrode (12) of the sensor element and the element contact portion (31) of the terminal metal fitting (30)), damage (nick) of the components constituting the gas sensor, etc. That is, the above-mentioned impact test was conducted on a plurality of gas sensors of gear 1 (set to 10 in the test), and after the impact test was conducted, it was confirmed whether the plurality of gas sensors had problems such as poor conduction and component damage. Similarly, the impact test is performed on the gas sensors of each of the gears 2 to 6. After the impact test is performed, it is confirmed whether the gas sensors have problems such as poor conduction and component damage. The situation where the problems such as poor conduction and component damage occur is set as "NG (bad)", and the number of gas sensors judged as NG (accumulated NG number) for the 10 gas sensors of each gear is sorted according to the drop height and is shown in Table 1.

[0174] As shown in Table 1, for the 10 gas sensors in gear position 1, no gas sensors had problems such as poor conduction and component damage during the drop height of 1.0 to 1.4 (the cumulative NG number was 0). The number of gas sensors that had NG (the cumulative NG number) among the 10 gas sensors in gear position 1 was 1 when the drop height was 1.6, 3 when the drop height was 1.8, and 6 when the drop height was 2.0.

[0175] Regarding the 10 gas sensors in gear position 2, no gas sensors had poor conduction or component damage during the drop height of 1.0 to 1.6 (the cumulative NG number was 0). The number of gas sensors that failed in gear position 2 (the cumulative NG number) was 2 when the drop height was 1.8, and 6 when the drop height was 2.0.

[0176] Regarding the 10 gas sensors in gear position 3, no gas sensors had poor conduction or component damage during the drop height of 1.0 to 1.6 (the cumulative NG number was 0). The number of gas sensors that had NG (the cumulative NG number) among the 10 gas sensors in gear position 3 was 2 when the drop height was 1.8, and 5 when the drop height was 2.0.

[0177] Regarding the 10 gas sensors in gear position 4, no gas sensors had poor conduction or component damage when the drop height was 1.0 (the cumulative NG number was 0). The number of gas sensors that had NG (the cumulative NG number) among the 10 gas sensors in gear position 4 was 1 when the drop height was 1.2, 4 when the drop height was 1.4, 7 when the drop height was 1.6, and 10 when the drop heights were 1.8 and 2.0.

[0178] The number of gas sensors that failed to meet the NG requirement (cumulative number of NG) among the 10 gas sensors in gear 5 was 2 when the drop height was 1.0, 3 when the drop height was 1.2 and 1.4, and 10 when the drop height was above 1.6.

[0179] The number of gas sensors that tested NG (cumulative NG number) among the 10 gas sensors in gear 6 was 1 when the falling height was 1.0, 3 when the falling heights were 1.2 and 1.4, 9 when the falling height was 1.6, and 10 when the falling height was above 1.8.

[0180] Therefore, the inventors of the present invention have confirmed the following phenomena through the impact test and its test results (evaluation) described above. First, the inventors of the present invention have confirmed that the gas sensors of gears 1 to 3 have significantly higher impact resistance than the gas sensor of gear 4. That is, the gas sensors of gears 1 to 3, whose Young's modulus of the material constituting the hollow component is 193 or more, have significantly higher impact resistance than the gas sensor of gear 4, whose Young's modulus of the material is less than 193 (specifically 72). If the Young's modulus of the material constituting the hollow component is less than 193, the hollow component is easily deformed or damaged, and it becomes difficult to reliably (stably) prevent the movement of the ceramic shell to the front end side by the hollow component, and the impact resistance of the gas sensor is reduced. In order to have the impact resistance of the gas sensor, especially to reliably prevent the movement of the ceramic shell to the front end side, it is required that "the hollow component has sufficient hardness". The inventors of the present invention have confirmed that by making the Young's modulus of the material constituting the hollow component to be 193 or more, the hollow component can be used to reliably prevent the ceramic shell from moving toward the front end side, thereby significantly improving the impact resistance of the gas sensor. Therefore, by making the Young's modulus of the material constituting the hollow component to be 193 or more, the impact resistance of the gas sensor can be significantly improved.

[0181] Second, the inventors of the present invention have confirmed that the gas sensors of the range 1 to range 3 have significantly higher impact resistance than the gas sensor of the range 5. That is, the gas sensors of the range 1 to range 3, whose Young's modulus of the material constituting the hollow component is 206 or less, have significantly higher impact resistance than the gas sensor of the range 5, whose Young's modulus of the material is greater than 206 (specifically 360). Therefore, by making the Young's modulus of the material constituting the hollow component 206 or less, the impact resistance of the gas sensor can be significantly improved.

[0182] Third, the inventors of the present invention have confirmed that the gas sensors of positions 1 to 3 have significantly higher impact resistance than the gas sensor of position 6. That is, the gas sensors of positions 1 to 3 having a hollow component between the main metal part and the ceramic shell have significantly higher impact resistance than the gas sensor of position 6 (conventional gas sensor) not having the hollow component. Therefore, by having a hollow component disposed between the main metal part and the ceramic shell, the impact resistance of the gas sensor can be significantly improved.

[0183] As described above, the inventors of the present invention have confirmed that the following effects can be achieved by arranging a hollow member between the main metal member and the ceramic shell, and in particular, by making the Young's modulus of the material constituting the hollow member greater than or equal to 193 and less than or equal to 206. That is, the inventors of the present invention have confirmed that the impact resistance of the gas sensor can be significantly improved by arranging a hollow member made of a material having a Young's modulus of greater than or equal to 193 and less than or equal to 206 between the main metal member and the ceramic shell.

[0184] <Second Test>

[0185] The inventors of the present invention produced gas sensors of the following ranges (Examples) 7 to 11 to verify the additional effect of the present invention (heat resistance of the gas sensor) and conducted heat load tests on a plurality of gas sensors of each range. However, the present invention is not limited to the following ranges (Examples).

[0186] Table 2

[0187]

[0188] The gas sensors for gears 7 to 10 are respectively Figure 1 The gas sensors of the configuration (components) illustrated in the figure are gas sensors in which a hollow component is arranged between the main metal part and the ceramic shell. The hollow component of the gas sensors of the gears 7 to 10 is composed of a material with a Young's modulus of 193 to 206 GPa. However, in the gas sensors of the gears 7 to 10, the plate thickness of the material (e.g., metal plate) constituting the hollow component is different from each other.

[0189] That is, the gas sensors of the range 7 to 10 are respectively provided with a hollow component in the inner part of the outer tube, the front end side of which is in contact with the rear end side of the main metal part, and the rear end side of which is in contact with the front end side of the ceramic shell. In addition, in the gas sensors of the range 7 to 10, the sensor element respectively penetrates the interior of the above-mentioned hollow component in the axial direction. The common point of the gas sensors of the range 7 to 10 is that they are provided with the hollow component, but the plate thickness of the material constituting the hollow component is different from each other in the gas sensors of the range 7 to 10. Specifically, in the gas sensor of the range 7, the hollow component is composed of a metal plate with a Young's modulus of 200 and a plate thickness of 0.3. In the gas sensor of the range 8, the hollow component is composed of a metal plate with a Young's modulus of 200 and a plate thickness of 0.5. In addition, in the gas sensor of the range 9, the hollow component is composed of a metal plate with a Young's modulus of 200 and a plate thickness of 0.8. In the gas sensor of the gear position 10, the hollow member is formed of a metal plate with a Young's modulus of 200 and a plate thickness of 1.2.

[0190] In contrast, the gas sensor for the shift position 11 is a conventional gas sensor as disclosed in the above-mentioned Patent Document 1 (Japanese Patent Application Laid-Open No. 2022-173747), and is the same gas sensor as the gas sensor for the shift position 6 in Table 1 above.

[0191] In order to compare the heat resistance of the gas sensor, the inventors of the present invention conducted a heat load test in which HEX (main metal part) was heated to about 440 [°C] (hereinafter, the unit [°C] is omitted) for each of the gas sensors of the ranges 7 to 11. For example, the gas sensors of the ranges 7 to 11 were placed in an environment where the external temperature around the gas sensor was about 440 for a predetermined time, so that the temperature of HEX reached about 440. Then, the inventors of the present invention measured (confirmed) the temperature (TC temperature) of the elastic body (50) when the temperature of HEX was about 440 for each of the gas sensors of the ranges 7 to 11. Table 2 shows the TC temperature of the elastic body (equivalent to the rubber cap of the conventional gas sensor) when the temperature of HEX was about 440 for the gas sensor of each range. The elastic body may melt when the temperature rises. When the melting occurs, the reference gas (reference air) in the outer cylinder (22) may be contaminated, or the shock resistance of the gas sensor may be deteriorated. In addition, the electrode provided in the sensor element (for example, the reference electrode provided so as to be in contact with the reference gas) may be contaminated by the organic gas accompanying the thermal decomposition of the elastic body. The lower the temperature of the elastic body is, the more it is possible to prevent the contamination of the reference gas and the reference electrode, the deterioration of the shock resistance of the gas sensor, etc.

[0192] As shown in Table 2, regarding the gas sensors in the respective gears 7 to 11, the TC temperatures of the elastic body 50 when the HEX temperature was approximately 440°C were 283.9, 286.5, 292.7, 315.7, and 317.1.

[0193] Therefore, the inventors of the present invention have confirmed the following phenomena through the above-mentioned heat load test and its test results (measurement results). First, the inventors of the present invention have confirmed that the temperature of each elastic body (TC temperature) of the gas sensors of the gears 7 to 10 is lower than that of the gas sensor of the gear 11, that is, the heat resistance is higher. That is, the gas sensors of the gears 7 to 10 having a hollow part between the main metal part and the ceramic shell can effectively suppress heat transfer to the elastic body compared with the gas sensor of the gear 11 (conventional gas sensor) that does not have the hollow part, and have higher heat resistance.

[0194] Second, the inventors of the present invention have confirmed that the temperature of the elastic body of the gas sensors of positions 7 to 9 is significantly lower than that of the gas sensor of position 10, that is, the heat resistance is significantly higher. That is, the gas sensors of positions 7 to 9 in which the plate thickness of the material constituting the hollow component is less than 0.8 have significantly higher heat resistance than the gas sensor of position 10 in which the plate thickness of the material is greater than 0.8 (specifically 1.2). Therefore, by making the plate thickness of the material constituting the hollow component less than 0.8, the heat resistance of the gas sensor can be significantly improved. In the gas sensor, the heat resistance can be improved by arranging the hollow component between the main metal part and the ceramic shell, and in particular, by making the plate thickness of the material constituting the hollow component less than 0.8, the heat resistance can be significantly improved.

[0195] It should be noted that, considering mass production and the like, it is unrealistic to use a material with a thickness of less than 0.3 (e.g., a metal plate with a thickness of less than 0.3) to form the above-mentioned hollow component. In addition, as described above, the gas sensor prevents the ceramic shell from moving toward the front end side through the hollow component. However, when the thickness of the material constituting the hollow component is less than 0.3, the hollow component may not be able to prevent the ceramic shell from moving toward the front end side. That is, when the thickness of the material constituting the hollow component is less than 0.3, the hollow component may not have sufficient strength to prevent the ceramic shell from moving toward the front end side. Therefore, the thickness of the material constituting the hollow component is preferably greater than 0.3.

[0196] As described above, the inventors of the present invention have confirmed that the following effects can be achieved by arranging a hollow component between the main metal part and the ceramic shell, and in particular, by making the plate thickness of the material constituting the hollow component greater than or equal to 0.3 and less than or equal to 0.8. That is, the inventors of the present invention have confirmed that the heat resistance of the gas sensor can be significantly improved by arranging a hollow component made of a material with a plate thickness of greater than or equal to 0.3 and less than or equal to 0.8 between the main metal part and the ceramic shell.

Claims

1. A gas sensor comprising: a sensor element extending in the axial direction and having a connector electrode on the rear end side; A cylindrical main metal member, wherein the sensor element penetrates the interior of the main metal member along the axial direction; a cylindrical outer cylinder extending in the axial direction and mounted on the outer peripheral surface of the rear end side of the main metal member; a terminal metal member extending in the axial direction and having a component contact portion electrically connected to the connector electrode at a front end side; A ceramic shell, which accommodates the connector electrode and the element contact portion and is disposed inside the outer cylinder; an elastic body arranged so as to close the open end on the rear end side of the outer tube; as well as A hollow component is arranged inside the outer cylinder, the sensor element passes through the interior of the hollow component along the axial direction, the front end side in the axial direction contacts the rear end side of the main metal part, and the rear end side in the axial direction contacts the front end side of the ceramic shell, and is composed of a material with a Young's modulus of 193 to 206 GPa.

2. The gas sensor according to claim 1, wherein: The hollow member is composed of a thin plate with a thickness of 0.3 to 0.8 mm.

3. The gas sensor according to claim 1 or 2, wherein: The hollow component is composed of a plurality of components.

4. The gas sensor according to claim 1 or 2, wherein: The hollow component and the main metal component are integrally formed.

5. The gas sensor according to claim 1 or 2, wherein: The ceramic housing is isolated from the elastomer.

6. The gas sensor according to claim 1 or 2, wherein: The main metal member includes a surface orthogonal to the axial direction on the rear end side, The hollow member is in contact with a surface of the metal body that is orthogonal to the axial direction.

7. The gas sensor according to claim 1 or 2, wherein: The hollow member is isolated from the sensor element.

8. The gas sensor according to claim 1 or 2, wherein: The gas sensor further includes a spacer disposed between the ceramic housing and the elastic body in the axial direction.

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