Gas sensor

Abstract

The present invention provides a gas sensor capable of preventing a ceramic case from being caught in a member disposed on the rear end side of the ceramic case in a state of being inclined from the axial direction. In a gas sensor according to one aspect of the present invention, a spacer having a Young's modulus of 80 GPa or more is disposed in at least the front end portion of the rear end side of a ceramic case to which a terminal fitting is attached.

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 cylindrical body, in which a sensor element and a connector (ceramic shell) equipped with a contact metal part electrically connected to the sensor element are arranged; and an elastic body that closes the open end of the cylindrical body. In the gas sensor disclosed in patent document 1, the elastic body is arranged on the rear end side of the ceramic shell in the axial direction of the gas sensor (the axial direction of the sensor element).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-196917 Summary of the invention

[0006] The inventors of the present invention have discovered that, in the conventional gas sensor disclosed in Patent Document 1, when the internal ceramic shell of the cylindrical body is fixed in a state tilted from the axial direction, the following problem occurs. That is, when the ceramic shell is fixed in a state tilted from the axial direction, unintended stress (e.g., stress in a direction other than the direction orthogonal to the axial direction) is applied from the sensor element to the terminal metal fitting assembled in the ceramic shell and connected to the sensor element. Therefore, the inventors of the present invention have discovered the following problem: in a gas sensor, when the ceramic shell is fixed in a state tilted from the axial direction, when an impact is applied to the gas sensor, the terminal metal fitting is more likely to break than when the ceramic shell is fixed parallel to the axial direction.

[0007] The inventors of the present invention have further studied and determined that the phenomenon that the ceramic shell is fixed in a state tilted from the axial direction occurs, for example, as follows. That is, in the conventional gas sensor, the Young's modulus of the elastic body that is arranged on the rear end side of the ceramic shell and closes the open end of the cylindrical body is lower than that of the ceramic shell, that is, it is softer than the ceramic shell. Therefore, the inventors of the present invention have determined that: in the manufacturing stage of the gas sensor, for example, the ceramic shell is sunk into the elastic body that is softer than the ceramic shell in a state tilted from the axial direction, thereby causing the above phenomenon.

[0008] As described above, the inventors of the present invention have found that when the ceramic case is sunk into a component (eg, an elastic body) disposed on the rear end side of the ceramic case in a state inclined from the axial direction, the terminal fitting attached to the ceramic case is easily broken.

[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 capable of preventing a ceramic housing from sinking into a component disposed on the rear end side of the ceramic housing in a state tilted from the axial direction.

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

[0011] The gas sensor involved in the first viewpoint comprises: a sensor element, which extends in the axial direction, has a detection portion on the front end side, and has a connector electrode on the rear end side; a terminal metal fitting, which extends in the axial direction and has an element contact portion electrically connected to the connector electrode on the front end side; a ceramic shell, which accommodates the connector electrode and the element contact portion; a cylindrical body, in the interior of which the sensor element, the terminal metal fitting and the ceramic shell are arranged and an open end is formed; an elastomer, which is arranged in a manner to close the open end; and a spacer, which is arranged between the ceramic shell and the elastomer in the axial direction, and the end face on the front end side in the axial direction is in contact with the ceramic shell, and the end face on the rear end side in the axial direction is in contact with the elastomer, and the Young's modulus of the front end portion including at least the end face on the front end side is greater than 80 GPa.

[0012] With this configuration, in the gas sensor, the ceramic case contacts the tip portion of the spacer disposed on the rear end side of the ceramic case, the tip portion having a Young's modulus of 80 GPa or more.

[0013] The inventors of the present invention believe that by arranging the spacer between the ceramic housing and the elastic body, it is possible to prevent the ceramic housing from sinking into the elastic body. Therefore, in the gas sensor, the spacer is arranged between the ceramic housing and the elastic body.

[0014] The inventors of the present invention also believe that in order to prevent the ceramic shell from sinking into the component arranged on the rear end side of the ceramic shell, it is effective to make the portion on the front end side in the axial direction of the component arranged on the rear end side sufficiently hard. Here, as described above, in the gas sensor, the spacer is arranged between the ceramic shell and the elastomer. Therefore, the inventors of the present invention experimentally determined the hardness (softness) that the front end portion of the spacer should have in order to prevent the ceramic shell from sinking into the spacer (especially the front end portion of the spacer). As a result, the inventors of the present invention confirmed that by making the Young's modulus of the front end portion of the spacer greater than 80 GPa, the ceramic shell can be significantly prevented from sinking into the spacer (especially the front end portion) compared to the case where it is less than 80 GPa.

[0015] In the gas sensor, the ceramic shell contacts the spacer disposed on the rear end side of the ceramic shell, and in particular, contacts the end face of the front end side of the spacer. Furthermore, the Young's modulus of the front end portion of the spacer including the end face of the front end side is 80 GPa or more, and has sufficient hardness to significantly prevent the ceramic shell from sinking into the spacer (in particular, the front end portion).

[0016] Therefore, in the gas sensor, there does not occur a phenomenon in which the ceramic case is sunk into the spacer disposed on the rear end side of the ceramic case in a state of being tilted from the axial direction and is fixed in this state.

[0017] Therefore, the gas sensor can achieve the effect of preventing the ceramic housing from being sunk into the member (that is, the spacer) disposed on the rear end side of the ceramic housing in a state of being tilted from the axial direction.

[0018] The gas sensor according to the second viewpoint is based on the gas sensor according to the first viewpoint, and the Young's modulus of the rear end portion of the spacer including the end face on the rear end side can be smaller than the Young's modulus of the front end portion of the spacer. Regarding this configuration, in the gas sensor, the Young's modulus of the rear end portion of the spacer including the end face on the rear end side is smaller than the Young's modulus of the front end portion. That is, in the gas sensor, the rear end portion of the spacer is softer and easier to bend than the front end portion of the spacer. In addition, in the gas sensor, the end face of the spacer on the rear end side in the axial direction is in contact with the elastomer.

[0019] Therefore, in the gas sensor, even if the end face (front end face) of the elastic body on the front end side in the axial direction is inclined relative to the axial direction, the inclination of the front end face of the elastic body can be absorbed at the rear end portion of the spacer. That is, in the gas sensor, the inclination of the front end face of the elastic body can be absorbed at the rear end portion of the spacer by the deflection of the soft rear end portion of the spacer in contact with the front end face of the elastic body.

[0020] The spacer prevents "the inclination of the front end face of the elastomer from being transmitted to the ceramic shell via the spacer, causing the ceramic shell to tilt from the axial direction" by means of the rear end portion that is softer and more flexible than the front end portion. For example, in a case where the front end face of the elastomer is tilted from the axial direction, stress in the direction of inclination from the axial direction is sometimes transmitted from the front end face of the elastomer to the ceramic shell, causing the ceramic shell to tilt from the axial direction due to the stress. The spacer prevents this situation by means of the rear end portion that is softer and more flexible than the front end portion. That is, the spacer absorbs the stress in the direction of inclination from the axial direction from the front end face of the elastomer through the rear end portion, thereby preventing the ceramic shell from tilting from the axial direction due to the stress. Furthermore, the front end portion of the spacer has a hardness sufficient to significantly prevent the ceramic shell from sinking into the spacer.

[0021] Therefore, the gas sensor can more effectively prevent the ceramic housing from sinking into the member (that is, the spacer) disposed on the rear end side of the ceramic housing in a state tilted from the axial direction.

[0022] The gas sensor according to the third aspect is the gas sensor according to the first or second aspect, wherein the contact area between the spacer and the ceramic housing can be 3 mm 2 Regarding this configuration, in the gas sensor, the contact area between the spacer and the ceramic housing is 3 mm 2 above.

[0023] The inventors of the present invention believe that in order to prevent the ceramic shell from being fixed in a state tilted from the axial direction, it is effective to fully ensure the contact area between the spacer and the ceramic shell (hereinafter referred to as "contact area A1"). For example, if the contact area A1 is small, it is easier to generate a force from the spacer toward the ceramic shell in a direction tilted from the axial direction than in a case where the contact area A1 is large. As a result, the ceramic shell is easily tilted from the axial direction. In addition, it is considered that if the contact area A1 is small, the contact between the spacer and the ceramic shell is unstable compared to a case where the contact area A1 is large. As a result, in a case where, for example, an impact is applied to the gas sensor, the ceramic shell is easily tilted from the axial direction. Therefore, the inventors of the present invention verified the range of the contact area A1 between the spacer and the ceramic shell that is effective in preventing the ceramic shell from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by setting the contact area A1 to 3 mm 2 Above, and make it less than 3mm 2Compared with the case where the ceramic shell is fixed in a state tilted from the axial direction, it is possible to significantly prevent the ceramic shell from being fixed in a state tilted from the axial direction.

[0024] In the gas sensor, the contact area (contact area A1) between the spacer and the ceramic housing is 3 mm 2 Therefore, the gas sensor has the following effect: the contact area A1 between the spacer and the ceramic shell is less than 3 mm 2 Compared with the case of FIG. 1 , the ceramic housing can be significantly prevented from being fixed in a state tilted from the axial direction.

[0025] Here, for example, the gas sensor is manufactured through the following process. That is, first, a contact component (pre-assembly) is prepared in which the ceramic shell equipped with the terminal metal fitting, the spacer, and the elastomer are arranged in this order starting from the front end side in the axial direction. At the time of pre-assembly, the outer periphery of the ceramic shell may not yet be installed with the "fixing metal part with a pressing spring" and the "riveting ring" described later. When the pre-assembly is completed, next, the rear end side of the sensor element is inserted into the ceramic shell equipped with the terminal metal fitting (especially the insertion port provided on the front end side of the ceramic shell). Then, the rivet ring provided to fix the ceramic shell with the sensor element inserted from the outer periphery is riveted, thereby integrating the sensor element and the ceramic shell (contact component).

[0026] However, if the ceramic housing is tilted from the axial direction at the time of pre-assembly, the ceramic housing is integrated with the sensor element in the tilted state, that is, the ceramic housing is fixed in the tilted state from the axial direction.

[0027] Therefore, for example, by ensuring the contact area A1 between the spacer and the ceramic shell sufficiently at the time of pre-assembly, it is possible to prevent the ceramic shell from being positioned in a state tilted from the axial direction in the above-mentioned contact component. Specifically, by making the contact area A1 3 mm at the time of pre-assembly 2 As described above, the gas sensor can prevent the occurrence of a situation in which “the ceramic housing is positioned in a state tilted from the axial direction at the time of pre-assembly”.

[0028] The gas sensor according to the fourth aspect is the gas sensor according to any one of the first to third aspects, wherein the area of ​​the portion of the end surface on the front end side of the elastomer that contacts the spacer may be 25% or more of the entire area of ​​the end surface on the front end side of the elastomer. With regard to this configuration, in the gas sensor, the area of ​​the portion of the end surface on the front end side of the elastomer that contacts the spacer is 25% or more of the entire area of ​​the end surface on the front end side of the elastomer.

[0029] The inventors of the present invention believe that it is effective to sufficiently ensure the contact area (hereinafter referred to as "contact area A2") between the spacer and the elastic body in order to prevent the ceramic shell from being fixed in a state tilted from the axial direction. For example, if the contact area A2 is small, it is easy to generate a force in the direction tilted from the axial direction from the elastic body toward the spacer compared to the case where the contact area A2 is large, and as a result, the ceramic shell in contact with the spacer is also easy to tilt from the axial direction. In addition, it is believed that if the contact area A2 is small, the contact between the elastic body and the spacer is unstable compared to the case where the contact area A2 is large, and the spacer (especially its end face) is easy to tilt from the axial direction when, for example, an impact is applied to the gas sensor. In addition, it is believed that because the spacer (especially its end face) is tilted from the axial direction, the ceramic shell in contact with the spacer (especially its end face on the front end side) is also easy to tilt from the axial direction. Therefore, the inventors of the present invention verified the range of the contact area A2 between the spacer and the elastic body that is effective in preventing the ceramic shell from being fixed in a state tilted from the axial direction. The inventors of the present invention have confirmed that by making the contact area A2 greater than 25% of the entire area of ​​the end surface on the front end side of the elastic body, the ceramic shell can be significantly prevented from being fixed in a state tilted from the axial direction, compared with a case where it is less than 25%.

[0030] In the gas sensor, the area of ​​the portion of the end surface on the front end side of the elastic body that contacts the spacer, that is, the contact area A2 is greater than or equal to 25% of the entire area of ​​the end surface on the front end side of the elastic body.

[0031] Therefore, the gas sensor exhibits an effect of significantly preventing the ceramic housing from being fixed in a state tilted from the axial direction, compared with a case where the contact area A2 is smaller than 25% of the entire area of ​​the end surface on the front end side of the elastic body.

[0032] Here, for example, the gas sensor is manufactured through the following process. That is, the gas sensor is manufactured through the following riveting process, in which the elastic body arranged at the open end of the cylindrical body and the cylindrical body are riveted in a reduced diameter shape, thereby fixing the elastic body to the open end, and the open end is closed by the elastic body. In this riveting process, the elastic body may be deformed, and stress is generated in the direction inclined from the axial direction for the spacer. For example, in the riveting process, the front end surface of the elastic body may be pushed out to the front end side in the axial direction in a state inclined from the axial direction, and stress in the direction inclined from the axial direction is applied to the spacer. At the time of the riveting process, if the contact area A2 between the spacer and the elastic body is small, the spacer is unstable because the elastic body is soft, and stress is generated in the direction inclined from the axial direction from the elastic body toward the spacer, so that the spacer is easily inclined from the axial direction. Furthermore, since the spacer (particularly the front end surface thereof) is inclined from the axial direction, the ceramic housing in contact with the spacer may also be inclined from the axial direction.

[0033] Therefore, for example, during the above-mentioned riveting process, by sufficiently ensuring the contact area A2 between the spacer and the elastic body in advance, the gas sensor can prevent the ceramic shell from tilting from the axial direction. Specifically, during the riveting process, by making the contact area A2 more than 25% of the entire area of ​​the end face on the front end side of the elastic body, the gas sensor can prevent the ceramic shell from tilting from the axial direction during the riveting process.

[0034] The gas sensor according to the fifth aspect is based on the gas sensor according to any one of the first to fourth aspects, and the distance from the position of the center of mass when the mass is evenly distributed at the end surface of the front end side of the spacer in contact with the ceramic shell, that is, the center of gravity of the end surface of the front end side of the spacer in contact with the ceramic shell, to the straight line obtained by extending the axis of the sensor element along the axial direction can be within 2 mm. With regard to this configuration, in the gas sensor, the distance from the position of the center of gravity of the portion of the spacer in contact with the ceramic shell (hereinafter referred to as "center of gravity CG1") to the straight line obtained by extending the axis along the axial direction (hereinafter referred to as "distance L1") is within 2 mm.

[0035] The inventors of the present invention believe that in order to prevent the ceramic shell from being fixed in a state tilted from the axial direction, it is effective to make the spacer and the ceramic shell contact on a straight line obtained by extending the axis along the axial direction (that is, the extension line of the axis). In particular, it is believed that if the distance L1 from the center of gravity CG1 of the contact surface between the spacer and the ceramic shell to the extension line of the axis is made small enough, the ceramic shell can be effectively prevented from being fixed in a state tilted from the axial direction. Therefore, the inventors of the present invention verified the distance L1 from the center of gravity CG1 to the extension line of the axis that is effective in preventing the ceramic shell from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by making the distance L1 from the center of gravity CG1 to the extension line of the axis within 2 mm, the ceramic shell can be significantly prevented from being fixed in a state tilted from the axial direction compared to the case where the distance L1 is greater than 2 mm.

[0036] In the gas sensor, a distance (ie, distance L1 ) from the position of the center of gravity (ie, center of gravity CG1 ) of the portion of the spacer in contact with the ceramic case to an extension line of the axis is within 2 mm.

[0037] Therefore, the gas sensor exhibits an effect of significantly preventing the ceramic housing from being fixed in a state tilted from the axial direction, compared with a case where the distance L1 from the center of gravity CG1 to the extension line of the axis is greater than 2 mm.

[0038] For example, the gas sensor is manufactured through the above-mentioned preassembly process. However, if the ceramic shell is tilted from the axial direction at the time of preassembly, the ceramic shell is integrated with the sensor element in the tilted state, that is, the ceramic shell is fixed in the tilted state from the axial direction.

[0039] Therefore, for example, at the time of pre-assembly, by bringing the spacer and the ceramic shell into contact on the extension line of the axis, it is possible to prevent the ceramic shell in the contact part from being positioned in a state tilted from the axial direction. Specifically, at the time of pre-assembly, the distance L1 from the center of gravity CG1 of the contact surface between the spacer and the ceramic shell to the extension line of the axis is within 2 mm. Accordingly, the gas sensor can prevent the occurrence of a situation in which "at the time of pre-assembly, the ceramic shell is positioned in a state tilted from the axial direction".

[0040] The gas sensor according to the sixth aspect is a gas sensor according to any one of the first to fifth aspects, wherein the distance from the position of the center of mass when the mass is evenly distributed at the end surface of the front end side of the elastic body in contact with the spacer, that is, the center of gravity of the end surface of the front end side of the elastic body in contact with the spacer, to a straight line obtained by extending the axis of the sensor element along the axial direction can be within 2 mm. With regard to this configuration, in the gas sensor, the distance from the position of the center of gravity of the portion of the elastic body in contact with the spacer (hereinafter referred to as "center of gravity CG2") to a straight line obtained by extending the axis along the axial direction (hereinafter referred to as "distance L2") is within 2 mm.

[0041] The inventors of the present invention believe that in order to prevent the ceramic shell from being fixed in a state tilted from the axial direction, it is effective to make the elastomer and the spacer contact on a straight line obtained by extending the axis along the axial direction (that is, the extension line of the axis). In particular, it is believed that if the distance L2 from the center of gravity CG2 of the contact surface between the elastomer and the spacer to the extension line of the axis is made small enough, the ceramic shell can be effectively prevented from being fixed in a state tilted from the axial direction. Therefore, the inventors of the present invention verified the distance L2 from the center of gravity CG2 to the extension line of the axis that is effective in preventing the ceramic shell from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by making the distance L2 from the center of gravity CG2 to the extension line of the axis within 2 mm, the ceramic shell can be significantly prevented from being fixed in a state tilted from the axial direction compared to the case where the distance L2 is greater than 2 mm.

[0042] In the gas sensor, the distance from the center of gravity of the portion of the elastic body in contact with the spacer (ie, center of gravity CG2) to a straight line extending the axis along the axial direction (ie, distance L2) is within 2 mm.

[0043] Therefore, the gas sensor exhibits the effect of significantly preventing the ceramic housing from being fixed in a state tilted from the axial direction, compared with a case where the distance L2 from the center of gravity CG2 to the extension line of the axis is greater than 2 mm.

[0044] For example, the gas sensor is manufactured through the above-mentioned riveting process. However, during the riveting process, the elastic body is deformed, and stress is generated from the elastic body toward the spacer in a direction inclined from the axial direction. As a result, the ceramic shell in contact with the spacer may also be inclined from the axial direction.

[0045] Thus, for example, during the riveting process, by making the elastic body and the spacer contact on the extension line of the axis, the gas sensor can prevent the ceramic shell from tilting from the axial direction. Specifically, during the riveting process, the distance L2 from the center of gravity CG2 to the extension line of the axis is within 2 mm. Accordingly, the gas sensor can prevent the occurrence of a situation in which "the ceramic shell is positioned in a state tilted from the axial direction during the riveting process."

[0046] The gas sensor according to the seventh aspect is a gas sensor according to any one of the first to sixth aspects, wherein the material of the elastomer may be fluororubber. With regard to this configuration, in the gas sensor, the material of the elastomer is fluororubber having excellent performance in various aspects such as tolerance and strength, especially excellent heat resistance and oil resistance. Therefore, the gas sensor has the following effects: for example, the sealing of the elastomer can be ensured even in a high temperature environment to maintain and improve the detection accuracy of the gas concentration.

[0047] The gas sensor involved in the eighth aspect is based on the gas sensor involved in any one of the first to seventh aspects mentioned above, and at least a part of the spacer can be composed of ceramic. Regarding this structure, in the gas sensor, at least a part of the spacer is composed of ceramic having excellent heat resistance and generally having a higher melting point than resin. In the gas sensor, the spacer is configured to be closer to the front end side than the elastomer in the axial direction. By using ceramic having excellent heat resistance to constitute at least a part of the spacer, the gas sensor exerts the following effect. That is, the gas sensor exerts the following effect: it can prevent the occurrence of a situation in which at least a part of the spacer is melted due to heat emitted from a heat source located on the front end side of the gas sensor.

[0048] Effects of the Invention

[0049] According to the present invention, it is possible to provide a gas sensor capable of preventing a ceramic housing from sinking into a component disposed on the rear end side of the ceramic housing in a state where the ceramic housing is tilted from the axial direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 FIG. 1 is a schematic cross-sectional view schematically showing an example of a main structure of a gas sensor according to an embodiment.

[0051] Figure 2 Yes Figure 1 FIG. 2 is an enlarged cross-sectional view of a main part showing an enlarged view of the rear end side of the gas sensor illustrated in FIG.

[0052] Figure 3 This is a cross-sectional schematic diagram schematically showing an example of the main structure of the gas sensor according to Modification 1.

[0053] Figure 4 This is a cross-sectional schematic diagram schematically showing an example of the main structure of a gas sensor according to Modification 2.

[0054] Figure 5 It is a graph showing changes in temperature and acceleration in a durability performance comparison test.

[0055] Explanation of symbols

[0056] 1, 1A, 1B…gas sensor; 10…sensor element; 11…detection part; 12…connector electrode; 20…cylindrical body; 30…terminal metal fitting; 31…element contact part; 50…elastic body; 60…ceramic housing; 70, 70A, 70B…spacer. DETAILED DESCRIPTION

[0057] 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 respects. 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.

[0058] The inventors of the present invention have discovered that, in a conventional gas sensor in which an elastic body is arranged on the rear end side in the axial direction of a sensor element in a ceramic shell equipped with a contact metal part, the following problem occurs when the ceramic shell is fixed in a state tilted from the axial direction. That is, when the ceramic shell is fixed in a state tilted from the axial direction, unintended stress (for example, stress in a direction other than the direction orthogonal to the axial direction) is applied from the sensor element to the terminal metal part assembled in the ceramic shell. Therefore, the inventors of the present invention have discovered the following problem: in a gas sensor, when the ceramic shell is fixed in a state tilted from the axial direction, when an impact is applied to the gas sensor, the terminal metal part is more likely to break than when the ceramic shell is fixed parallel to the axial direction.

[0059] The inventors of the present invention have further studied and determined that the phenomenon that the ceramic shell is fixed in a state tilted from the axial direction occurs, for example, as follows. That is, the inventors of the present invention have determined that the ceramic shell is sunk into an elastic body softer than the ceramic shell in a state tilted from the axial direction during the manufacturing stage of the gas sensor, and the above phenomenon occurs.

[0060] For example, conventional gas sensors are manufactured through the following pre-assembly process. That is, first, a contact component is prepared in which a ceramic shell equipped with terminal metal parts and an elastic body are arranged in this order from the front end side in the axial direction (pre-assembly process). Next, the rear end side of the sensor element is inserted into the contact component (particularly, an insertion port provided at the front end side of the ceramic shell). Then, a rivet ring provided to fix the ceramic shell with the sensor element inserted from the periphery is riveted, thereby integrating the sensor element and the ceramic shell (contact component).

[0061] In this embodiment, the end surface on the front end side of each component in the axial direction (axial direction of the sensor element) is also referred to as the "front end surface". Similarly, the end surface on the rear end side of each component in the axial direction is also referred to as the "rear end surface".

[0062] In the conventional gas sensor manufactured by this process, the ceramic shell sometimes sinks into the elastic body softer than the ceramic shell in a state tilted from the axial direction at the time of the pre-assembly process. In this case, in the subsequent process of integrating the sensor element and the ceramic shell, the ceramic shell is fixed in a state tilted from the axial direction. That is, the ceramic shell is integrated with the sensor element in this tilted state, and the ceramic shell is fixed in a state tilted from the axial direction.

[0063] In addition, for example, a conventional gas sensor is manufactured through the above-mentioned pre-assembly process and the following riveting process. That is, the gas sensor is manufactured through the following riveting process, in which a cylindrical body in which a sensor element and a contact member integrated with the sensor element are arranged and an elastic body arranged at the open end of the cylindrical body are riveted into a reduced diameter shape. In the riveting process, the elastic body is fixed to the open end of the cylindrical body, and the open end of the cylindrical body is closed by the elastic body.

[0064] During the riveting process, the soft elastic body used to close the open end of the cylindrical body is sometimes deformed, and the elastic body (especially the end face on the front end side in the axial direction) applies stress to the ceramic shell in a direction inclined from the axial direction. For example, during the riveting process, the front end face of the elastic body is sometimes pushed out to the front end side in the axial direction in a state inclined from the axial direction, and stress is applied to the ceramic shell in a direction inclined from the axial direction.

[0065] The inventors of the present invention have confirmed that, for example, during the manufacturing stage of the gas sensor (specifically, the above-mentioned pre-assembly step, riveting step, etc.), the ceramic housing may be fixed in this state by being sunk into the elastic body in a state tilted from the axial direction.

[0066] Therefore, the inventors of the present invention studied the use of spacers to prevent "the ceramic shell from sinking into an elastic body softer than the ceramic shell in a state tilted from the axial direction". That is, the inventors of the present invention believe that by arranging a spacer between the ceramic shell equipped with the terminal metal fitting and the soft elastic body that closes the open end of the cylindrical body, it is possible to prevent the ceramic shell from sinking into the elastic body in a state tilted from the axial direction. In addition, the inventors of the present invention believe that in order to prevent the ceramic shell from sinking into the spacer arranged on the rear end side of the ceramic shell, it is effective to make the axial front end side of the spacer sufficiently hard.

[0067] The inventors of the present invention have experimentally determined the hardness (softness) that the front end portion of the spacer should have in order to prevent the ceramic shell from sinking into the spacer (especially the front end portion of the spacer) (for details of the experiment, refer to the [Example] described later). As a result, the inventors of the present invention have confirmed that by making the Young's modulus of the front end portion of the spacer greater than 80 GPa, the ceramic shell can be significantly prevented from sinking into the spacer (especially the front end portion thereof) compared to the case where it is less than 80 GPa.

[0068] Therefore, the gas sensor involved in one aspect of the present invention has a spacer between a ceramic shell equipped with a terminal metal fitting and a soft elastic body that closes the open end of the cylindrical body. Furthermore, in the gas sensor involved in one aspect of the present invention, the ceramic shell is in contact with the spacer arranged on the rear end side of the ceramic shell, in particular, the end face (front end face) on the front end side of the spacer. In the gas sensor involved in one aspect of the present invention, the Young's modulus of the front end portion of the spacer including the front end face is greater than 80 GPa, that is, the front end portion of the spacer has sufficient hardness to significantly prevent the ceramic shell from sinking into the spacer (in particular, its front end portion).

[0069] Therefore, in the gas sensor involved in one aspect of the present invention, the phenomenon of "the ceramic shell is sunk into the spacer arranged on the rear end side of the ceramic shell in a state tilted from the axial direction, so that the state is fixed" does not occur. Therefore, the gas sensor involved in one aspect of the present invention exerts the following effect: it is possible to prevent the ceramic shell from being sunk into the component (that is, the spacer) arranged on the rear end side of the ceramic shell in a state tilted from the axial direction. In the gas sensor involved in one aspect of the present invention, by preventing "the ceramic shell is sunk into the component arranged on the rear end side of the ceramic shell in a state tilted from the axial direction", the possibility of breakage of the terminal metal parts can be suppressed even if an impact is applied to the gas sensor. Below, first, as a gas sensor involved in one aspect of the present invention, a Figure 1 and Figure 2 , the gas sensor 1 is described.

[0070] [Configuration example]

[0071] <Overview of Gas Sensor>

[0072] 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, 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 length direction (axial direction). In the present embodiment, the gas sensor 1 comprises: a sensor element 10, a cylindrical body 20 (a main metal part 21, an outer cylinder 22 and a fixing bolt 23), a terminal metal part 30, a wire 40, an elastic body 50, a ceramic shell 60, a spacer 70, and a protective cover 80. 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 as a whole constitute a storage component (housing) that stores the sensor element 10 inside. 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.

[0073] (Sensor element)

[0074] 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 1 The 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 at the front end side and a connector electrode (connector electrode 12) at the rear end side. The connector electrode 12 of the sensor element 10 is Figure 2 Example in. 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.

[0075] 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 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 obtained.

[0076] 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.

[0077] (Wrap-around assembly)

[0078] 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.

[0079] 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.

[0080] Figure 12 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 includes a surrounding mounting member 90 that fixes the sensor element 10 inside the metal shell 21 and hermetically seals the front end and rear end of the sensor element 10 .

[0081] (Tubular body)

[0082] The cylindrical body 20 is an example of the “cylindrical body” of the present invention. 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.

[0083] The main metal fitting 21 is a metal cylindrical (e.g., cylindrical) component. The sensor element 10 and the surrounding mounting component 90 for fixing and surrounding the sensor element 10 are accommodated inside the main metal fitting 21. That is, the main metal fitting 21 is further surrounded by the surrounding mounting component 90 surrounding the sensor element 10. Figure 1 The metal shell 21 illustrated in FIG. 2 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 part of each of the front end side and the rear end side.

[0084] The outer cylinder 22 is a metal cylindrical member (e.g., a round cylinder). Figure 1 The outer cylinder 22 illustrated in FIG. 1 covers the rear end of the sensor element 10 , the ceramic case 60 (the terminal metal fitting 30 ), and the periphery of the spacer 70 .

[0085] The end (open end) of the front end side of the outer tube 22 is 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 tube 22 in a manner to close the open end. A reduced diameter portion 221 is formed on the rear end side of the outer tube 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 tube 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 tube 22 is closed.

[0086] 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 external gas (atmosphere) passes between the film of the lead wire 40 and the metal wire (conductor) (in other words, the inside of the film) and is introduced into the internal space of the outer cylinder 22, and the internal space of the outer cylinder 22 becomes a reference gas (atmosphere) atmosphere. The rear end of the sensor element 10 is arranged in the internal space of the outer cylinder 22 filled with the reference gas.

[0087] 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.

[0088] As explained before, Figure 1 The cylindrical body 20 shown in the example includes: a main body metal part 21, an outer cylinder 22 and a fixing bolt 23, and the whole is a cylindrical component (for example, a cylindrical component), and is particularly a cylindrical component extending in the axial direction. Figure 1 The cylindrical body 20 illustrated in the figure is a cylindrical component extending in the axial direction, and includes: a cylindrical main body metal fitting 21; a cylindrical outer cylinder 22, which is welded and fixed to the outer peripheral end of the rear end side of the main body metal fitting 21; and a fixing bolt 23, which is arranged on the outer periphery of the front end side of the main body metal fitting 21. For example, the cylindrical body 20 and the gas sensor 1 (sensor element 10) are coaxial, and the cylindrical body 20 is arranged to have a front end and a rear end as each end in the axial direction (length direction), and the front end of the cylindrical body 20 faces the front end of the gas sensor 1. In addition, the sensor element 10, the surrounding assembly component 90 for fixing that is mounted around the sensor element 10, the ceramic housing 60 (terminal metal fitting 30) and the spacer 70 are accommodated inside the cylindrical body 20, and the open end on the rear end side is closed by the elastic body 50. A reduced diameter portion 221 for fixing the elastic body 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 caulks a part of the elastic body 50 from the periphery.

[0089] It should be noted that in the gas sensor 1, it is not necessary for the cylindrical body 20 to include the main metal member 21, the outer cylinder 22, and the fixing bolts 23. The cylindrical body 20 may not include the fixing bolts 23, and the main metal member 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.

[0090] (Terminal metal parts)

[0091] 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 lead wire 40 are electrically connected by means of the terminal metal fitting 30. Figure 2 As described in the figure, the terminal metal fitting 30 has an element contact portion 31 on the front end side which is electrically connected to the connector electrode 12 of the sensor element 10, and has a wire holding portion 32 on the rear end side which crimps and holds the wire 40.

[0092] (Ceramic housing)

[0093] The ceramic housing 60 is an example of the “ceramic housing” of the present invention. The ceramic housing 60 is: a connector electrode 12 provided on 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 a connector electrode 12 provided on the front end side of the terminal metal fitting 30 (specifically, the connector electrode 12 provided on the rear end side of the sensor element 10). Figure 2 The ceramic component that houses the element contact portion 31 described in the above description. 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 .

[0094] 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.

[0095] In the gas sensor 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. The ceramic shell 60 is integrated with the sensor element 10, so that its position inside the cylindrical body 20 can be fixed without contacting the cylindrical body 20. Figure 1 As shown in the example, the sensor element 10 is fixed in position inside the cylindrical body 20 by surrounding the fitting member 90 and the cylindrical body 20 (particularly the main metal fitting 21 and the outer cylinder 22). Since the sensor element 10 whose position inside the cylindrical body 20 is fixed by surrounding the fitting member 90 and the cylindrical body 20 is integrated, the ceramic housing 60 can be fixed in position inside the cylindrical body 20 without contacting the cylindrical body 20.

[0096] The ceramic shell 60 (more precisely, a contact component obtained by arranging the ceramic shell 60, the spacer 70, and the elastic body 50 in this order from the front end side in the axial direction) can be integrated with the sensor element 10 as follows. That is, after the front end of the wire 40 inserted through the elastic body 50 and the spacer 70 is connected to the wire holding portion 32 of the terminal metal fitting 30, the ceramic shell 60 having an insertion port provided on the front end side in the axial direction is installed for the terminal metal fitting 30. More precisely, for the terminal metal fitting 30 to which the front end of the wire 40 is connected to the wire holding portion 32, the ceramic shell 60 having the pressing spring 61 (see Figure 2 ) and the rivet ring 62 (see Figure 2 ) of a ceramic shell 60. After that, a fixing metal part having a pressing spring 61 and a rivet ring 62 are further installed on the outer periphery of the ceramic shell 60 to prepare a contact component (pre-assembly). The pressing spring 61 is a leaf spring component having a trapezoidal cross-section without an upper bottom portion, for example, and generates an elastic force as its restoring force when an external force acts on its free end. The rivet ring 62 is riveted in a state where the sensor element 10 (especially its rear end portion) is inserted into the insertion port of the ceramic shell 60 when the sensor element 10 and the above-mentioned contact component are integrated, that is, it is reduced and deformed by the external force. Accordingly, the interval of the insertion port of the ceramic shell 60 is narrowed, and the sensor element 10 and the ceramic shell 60 (contact component) are integrated. At this time, the element contact portion 31 of the terminal metal component 30 is in contact with the connector electrode 12 of the sensor element 10. Therefore, in the gas sensor 1 , electrical conduction between the sensor element 10 and the outside is achieved via the lead wire 40 connected to the terminal metal fitting 30 , or even the contact member (terminal metal fitting 30 ) connected to the lead wire 40 .

[0097] (wire)

[0098] The lead wire 40 is electrically connected to the connector electrode 12 of the sensor element 10 via the terminal metal fitting 30, and extends outward from the open end of the cylindrical body 20. Specifically, the lead wire 40 is connected at its front end to the rear end of the terminal metal fitting 30 (specifically, Figure 2 The wire holding portion 32 described in the figure is electrically connected to the lead wire 40, and the rear end side of the lead wire 40 extends outward from the open end of the cylindrical body 20. 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.

[0099] For example, the wire 40 is inserted into a through hole (not shown) continuously provided in the elastic body 50 and the spacer 70. The end of the front end side of the wire 40 is crimped and fixed to the rear end side (wire holding portion 32) 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.

[0100] (Elastomer)

[0101] 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 open end on the rear end side is closed and the wire 40 is inserted. 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.

[0102] 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, and the gas sensor 1 can appropriately use a raw material with elasticity for the material of the elastomer 50.

[0103] (Spacer)

[0104] The spacer 70 is an example of a "spacer" of the present invention. The spacer 70 is arranged between the ceramic shell 60 and the elastomer 50 in the axial direction of the gas sensor 1 (sensor element 10), specifically, it is arranged to be closer to the rear end side than the ceramic shell 60 and closer to the front end side than the elastomer 50. The spacer 70 contacts the ceramic shell 60 (especially the rear end face of the ceramic shell 60) at its front end face, and contacts the elastomer 50 (especially the front end face of the elastomer 50) at its rear end face. For example, the spacer 70 is fixed in position inside the cylindrical body 20 (outer cylinder 22) by the ceramic shell 60 and the elastomer 50. That is, the spacer 70 is sandwiched by the ceramic shell 60 and the elastomer 50 inside the cylindrical body 20 (between the ceramic shell 60 and the elastomer 50). That is, the front end face of the spacer 70 contacts the rear end face of the ceramic shell 60, and as described above, the ceramic shell 60 is integrated with the sensor element 10, thereby being fixed in position inside the cylindrical body 20. In addition, the rear end surface of the spacer 70 contacts the front end surface of the elastic body 50. As described above, the elastic body 50 is fixed to the open end of the cylindrical body 20 (at the end of the cylindrical body 20) by the reduced diameter portion 221. Figure 1 In the example shown, the open end on the rear end side. Therefore, the spacer 70 is fixed at a position inside the cylindrical body 20 (outer cylinder 22 ) by the ceramic shell 60 and the elastic body 50 .

[0105] exist Figure 1 The wire 40 is inserted into the spacer 70 illustrated in FIG. Figure 1 In the illustrated example, the lead wire 40 and the terminal metal fitting 30 (particularly, the rear end of the terminal metal fitting 30 electrically connected to the lead wire 40 ) are housed inside the spacer 70 .

[0106] The spacer 70 is made of, for example, a heat-resistant material. By making the spacer 70 of a heat-resistant material, it is possible to prevent the spacer 70, which is arranged closer to the front end side than the elastomer 50 in the axial direction, from being melted due to the heat emitted from the heat source located at the front end side of the gas sensor 1. For example, by placing the spacer 70 between the elastomer 50 and the ceramic housing 60, it is possible to prevent the elastomer 50 from being overheated when the gas sensor 1 is used. That is, from the viewpoint of suppressing heat transfer to the elastomer 50, it is preferred that the thermal conductivity of the spacer 70 is low. However, although the temperature rise of the elastomer 50 is suppressed by the spacer 70, the spacer 70 becomes a high temperature, and therefore, the spacer 70 itself needs to have sufficient heat resistance. Therefore, by making the spacer 70 of 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 70 itself from being melted due to the heat emitted from the heat source.

[0107] Specifically, in the gas sensor 1, the spacer 70 is made of ceramic. Ceramics have excellent heat resistance, and generally, have a higher melting point than resin. Furthermore, in the gas sensor 1, the spacer 70 is arranged to be closer to the front end side than the elastomer 50 in the axial direction. By using ceramics having excellent heat resistance to constitute the spacer 70, the gas sensor 1 exerts the following effect. That is, the gas sensor 1 exerts the following effect: it is possible to prevent the spacer 70 from being melted due to the heat emitted from the heat source located at the front end side of the gas sensor 1. However, it is not necessary for the gas sensor 1 to use ceramics to constitute the spacer 70, and the gas sensor 1 can appropriately use heat-resistant raw materials for the material of the spacer 70.

[0108] In the spacer 70, at least the tip portion including the tip surface has a Young's modulus of 80 GPa or more. In the gas sensor 1, the entire spacer 70 has a Young's modulus of 80 GPa or more, that is, not only the tip portion but also the entire spacer 70 has a Young's modulus of 80 GPa or more.

[0109] In the gas sensor 1, a spacer 70 is arranged between the ceramic shell 60 and the elastic body 50. In the gas sensor 1, the ceramic shell 60 (especially the rear end face thereof) contacts not the elastic body 50 but the spacer 70 arranged on the rear end side of the ceramic shell 60, especially the front end face of the spacer 70. Therefore, the gas sensor 1 can prevent the ceramic shell 60 from sinking into the elastic body 50 in a state tilted from the axial direction.

[0110] In particular, in the gas sensor 1, the ceramic housing 60 is in contact with the spacer 70 disposed on the rear end side of the ceramic housing 60, and in particular, in contact with the front end surface of the spacer 70. Furthermore, the Young's modulus of the front end portion of the spacer 70 including the front end surface is 80 GPa or more, that is, the front end portion of the spacer 70 has a hardness sufficient to significantly prevent the ceramic housing 60 from sinking into the spacer 70 (particularly the front end portion of the spacer 70).

[0111] Therefore, in the gas sensor 1, the phenomenon of "the ceramic shell 60 is sunk into the spacer 70 arranged on the rear end side of the ceramic shell 60 in a state tilted from the axial direction, and this state is fixed" does not occur. Therefore, the gas sensor 1 has the following effect: it is possible to prevent the ceramic shell 60 from being sunk into the component (that is, the spacer 70) arranged on the rear end side of the ceramic shell 60 in a state tilted from the axial direction. In the gas sensor 1, by preventing "the ceramic shell 60 from being sunk into the component arranged on the rear end side of the ceramic shell 60 in a state tilted from the axial direction", the possibility of the terminal metal fitting 30 being broken can be suppressed even if an impact is applied to the gas sensor 1.

[0112] (Protective cover)

[0113] 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 1 The 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.

[0114] 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.

[0115] 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 to cover 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.

[0116] 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.

[0117] 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 .

[0118] <Details of the rear end of the gas sensor>

[0119] Figure 2 1 is an enlarged cross-sectional view schematically showing a main part of the gas sensor 1 , and more specifically, is an enlarged cross-sectional view showing a main part with the rear end side of the gas sensor enlarged. 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.

[0120] like Figure 2 As shown in detail in FIG. 1 , on the rear end side of the gas sensor 1, from the front end side toward the rear end side, a ceramic shell 60, a spacer 70, and an elastic body 50 are sequentially arranged in the following order. The rear end face of the ceramic shell 60 is in contact with the front end face of the spacer 70, and the rear end face of the spacer 70 is in contact with the front end face of the elastic body 50. As described above, in the gas sensor 1, the Young's modulus of the entire spacer 70 is greater than 80 GPa. Therefore, in the gas sensor 1, the Young's modulus of the front end portion of the spacer 70 is greater than 80 GPa, that is, the ceramic shell 60 (especially the rear end face of the ceramic shell 60) is in contact with the spacer 70 (especially its front end face) having a Young's modulus of greater than 80 GPa.

[0121] Here, for example, the following steps are performed to produce Figure 1 and Figure 2 The gas sensor 1 shown in the example is prepared first, and the ceramic housing 60, the spacer 70, and the elastic body 50 are arranged in order from the front end side in the axial direction. At the time of pre-assembly, the outer periphery of the ceramic housing 60 may not be mounted. Figure 2 The fixing metal part and the rivet ring 62 with the pressing spring 61 are illustrated in the figure. As described above, the pressing spring 61 is, for example, a leaf spring part, and the rivet ring 62 is shrunk and deformed by an external force, thereby integrating the sensor element 10 and the ceramic housing 60 (contact part). When the pre-assembly is completed, the rear end side of the sensor element 10 is then inserted into the ceramic housing 60 (particularly, the insertion port provided at the front end side of the ceramic housing 60) equipped with the terminal metal part 30. Then, the rivet ring 62 provided to fix the ceramic housing 60 with the sensor element 10 inserted therein from the periphery is riveted, thereby integrating the sensor element 10 and the ceramic housing 60 (contact part).

[0122] The gas sensor 1 is manufactured through, for example, the following process in addition to the above-mentioned pre-assembly process. That is, the gas sensor 1 is manufactured through the following riveting process, in which the elastic body 50 disposed at the open end of the cylindrical body 20 (outer cylinder 22) and the cylindrical body 20 are riveted into a reduced diameter shape, thereby fixing the elastic body 50 to the open end of the cylindrical body 20, and the open end is sealed by the elastic body 50.

[0123] (Contact method between ceramic housing and spacer)

[0124] like Figure 2 As shown in the example, in the gas sensor 1, the contact area A1 between the spacer 70 (especially the front end surface of the spacer 70) and the ceramic shell 60 (especially the rear end surface of the ceramic shell 60) is adjusted to be sufficiently large. Specifically, in the gas sensor 1, the contact area A1 is 3 mm 2 However, in the gas sensor 1, the contact area A1 is set to 3 mm 2 The above is not necessary, the contact area A1 can be less than 3mm 2 .

[0125] The inventors of the present invention believe that in order to prevent the ceramic shell 60 from being fixed in a state tilted from the axial direction, it is effective to fully ensure the contact area A1 between the spacer 70 and the ceramic shell 60. For example, if the contact area A1 is small, it is easier to generate a force from the spacer 70 toward the ceramic shell 60 in the direction tilted from the axial direction than in the case where the contact area A1 is large. As a result, the ceramic shell 60 is easy to tilt from the axial direction. In addition, it is considered that if the contact area A1 is small, the contact between the spacer 70 and the ceramic shell 60 is unstable compared to the case where the contact area A1 is large. As a result, when, for example, an impact is applied to the gas sensor 1, the ceramic shell 60 is easy to tilt from the axial direction. Therefore, the inventors of the present invention verified the range of the contact area A1 between the spacer 70 and the ceramic shell 60 that is effective in preventing the ceramic shell 60 from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by setting the contact area A1 to 3 mm 2 Above, and make it less than 3mm 2 Compared with the case where the ceramic housing 60 is fixed in a state tilted from the axial direction, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0126] In the gas sensor 1, the contact area A1 between the spacer 70 and the ceramic housing 60 is 3 mm 2 Therefore, the gas sensor 1 has the following effects: the contact area A1 between the spacer 70 and the ceramic housing 60 is smaller than 3 mm. 2 Compared with the case where the ceramic housing 60 is fixed in a state tilted from the axial direction, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0127] Here, as described above, the gas sensor 1 is manufactured through, for example, a pre-assembly process. If the ceramic housing 60 is tilted from the axial direction at the time of pre-assembly, the ceramic housing 60 is integrated with the sensor element 10 in the tilted state, that is, the ceramic housing 60 is fixed in the tilted state from the axial direction.

[0128] Therefore, for example, by ensuring a sufficient contact area A1 between the spacer 70 and the ceramic housing 60 at the time of pre-assembly, it is possible to prevent the ceramic housing 60 from being positioned in a state tilted from the axial direction in the above-mentioned contact component. Specifically, by making the contact area A1 3 mm at the time of pre-assembly 2 As described above, the gas sensor 1 can prevent the occurrence of a situation in which “the ceramic case 60 is positioned in a state tilted from the axial direction at the time of pre-assembly”.

[0129] like Figure 2 As illustrated in , in the gas sensor 1, the spacer 70 and the ceramic shell 60 are in contact on a straight line obtained by extending the axis of the sensor element 10 (gas sensor 1) in the axial direction (that is, the extension line of the axis). For example, in the gas sensor 1, the distance L1 from the position of the center of gravity CG1 of "the portion of the spacer 70 (especially its front end surface) in contact with the ceramic shell 60 (especially its rear end surface)" to the extension line of the axis of the sensor element 10 is within 2 mm. The center of gravity CG1 is the center of mass when it is assumed that the mass is evenly distributed in the portion of the front end surface of the spacer 70 in contact with the ceramic shell 60 (especially the rear end surface of the ceramic shell 60). It should be noted that in the gas sensor 1, it is not necessary to make the distance L1 within 2 mm, and the distance L1 can be greater than 2 mm.

[0130] The inventors of the present invention believe that in order to prevent the ceramic shell 60 from being fixed in a state tilted from the axial direction, it is effective to make the spacer 70 and the ceramic shell 60 contact on the extension line of the axis of the sensor element 10 (gas sensor 1). In particular, it is believed that if the distance L1 from the center of gravity CG1 of the contact surface between the spacer 70 and the ceramic shell 60 to the extension line of the axis can be made sufficiently small, the ceramic shell 60 can be effectively prevented from being fixed in a state tilted from the axial direction. Therefore, the inventors of the present invention verified the distance L1 from the center of gravity CG1 to the extension line of the axis that is effective for preventing the ceramic shell 60 from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by making the distance L1 from the center of gravity CG1 to the extension line of the axis within 2 mm, the ceramic shell 60 can be significantly prevented from being fixed in a state tilted from the axial direction compared to the case where the distance L1 is greater than 2 mm.

[0131] In the gas sensor 1 , a distance L1 from the position of the center of gravity CG1 of the portion of the spacer 70 in contact with the ceramic case 60 to the extension line of the axis of the sensor element 10 (gas sensor 1 ) is within 2 mm.

[0132] Therefore, the gas sensor 1 exhibits an effect of significantly preventing the ceramic case 60 from being fixed in a state tilted from the axial direction, compared with a case where the distance L1 from the center of gravity CG1 to the extension line of the axis is greater than 2 mm.

[0133] Here, as described above, the gas sensor 1 is manufactured through, for example, a pre-assembly process. However, if the ceramic housing 60 is tilted from the axial direction at the time of pre-assembly, the ceramic housing 60 is integrated with the sensor element 10 in the tilted state, that is, the ceramic housing 60 is fixed in the tilted state from the axial direction.

[0134] Therefore, for example, at the time of pre-assembly, by making the spacer 70 and the ceramic shell 60 contact on the extension line of the axis, it is possible to prevent the ceramic shell 60 from being positioned in a state tilted from the axial direction in the contact part. Specifically, at the time of pre-assembly, the distance L1 from the center of gravity CG1 of the contact surface between the spacer 70 and the ceramic shell 60 to the extension line of the axis is within 2 mm. Accordingly, the gas sensor 1 can prevent the occurrence of a situation in which "the ceramic shell 60 is positioned in a state tilted from the axial direction at the time of pre-assembly".

[0135] It should be explained that Figure 1 and Figure 2 In the gas sensor 1 illustrated in FIG. 1 , the front end surface of the spacer 70 and the rear end surface of the ceramic housing 60 have the same area and shape, that is, the areas and shapes of both are substantially equal.

[0136] By making the area and shape of the front end face of the spacer 70 and the rear end face of the ceramic shell 60 substantially equal (identical), the gas sensor 1 can achieve the following effects. That is, when the front end face of the spacer 70 and the rear end face of the ceramic shell 60 are identical, it is easier to make the two contact each other on the extension line of the axis of the sensor element 10, for example, in the manufacturing stage of the gas sensor 1, compared with the case where the two are different. In particular, by making the front end face of the spacer 70 and the rear end face of the ceramic shell 60 identical, it is easier to make the distance L1 from the center of gravity CG1 of the contact portion of the two to the extension line of the axis of the sensor element 10 smaller (for example, within 2 mm) in the manufacturing stage. Here, the front end face of the spacer 70 and the rear end face of the ceramic shell 60 are "identical" means that, for example, both are circular or elliptical, and the difference in area between the two is less than about 40% of the area of ​​at least one of the two.

[0137] However, in the gas sensor 1, it is not necessary to make the front end face of the spacer 70 identical to the rear end face of the ceramic shell 60. For example, it is not necessary to make the front end face of the spacer 70 and the rear end face of the ceramic shell 60 substantially equal in area and shape. In the gas sensor according to one embodiment of the present invention, the front end face of the spacer and the rear end face of the ceramic shell may be identical or different from each other.

[0138] For example, in the gas sensor 1, the front end surface of the spacer 70 may be smaller than the rear end surface of the ceramic shell 60. Similarly, in the gas sensor 1, the front end surface of the spacer 70 may be larger than the rear end surface of the ceramic shell 60. By making the front end surface of the spacer 70 larger than the rear end surface of the ceramic shell 60, the gas sensor 1 exhibits the following effects. That is, in the case where the front end surface of the spacer 70 is larger than the rear end surface of the ceramic shell 60, compared with the case where the front end surface of the spacer 70 is smaller than the rear end surface of the ceramic shell 60, for example, in the manufacturing stage of the gas sensor 1, it is easier to fully ensure the contact area A1 between the two. Specifically, it is easier to make the contact area A1 3 mm. 2 As a gas sensor according to one embodiment of the present invention, the following uses Figure 4 , an example is described in which the front end surface of the spacer in contact with the ceramic shell (particularly the rear end surface thereof) is made larger than the rear end surface of the ceramic shell.

[0139] (Contact method between spacer and elastic body)

[0140] like Figure 2 As shown in the example in FIG. 1 , in the gas sensor 1, the contact area A2 between the spacer 70 (particularly the rear end face of the spacer 70) and the elastic body 50 (particularly the front end face of the elastic body 50) is adjusted to be sufficiently large. Specifically, in the gas sensor 1, the contact area A2 is 25% or more of the entire area of ​​the front end face of the elastic body 50. However, in the gas sensor 1, it is not necessary to make the contact area A2 25% or more of the entire area of ​​the front end face of the elastic body 50, and the contact area A2 may be less than 25% of the entire area of ​​the front end face of the elastic body 50.

[0141] The inventor of the present invention believes that it is effective to sufficiently ensure the contact area A2 between the spacer 70 and the elastic body 50 in order to prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction. For example, if the contact area A2 is small, it is easy to generate a force in the direction tilted from the axial direction from the elastic body 50 toward the spacer 70 compared with the case where the contact area A2 is large, and as a result, the ceramic housing 60 in contact with the spacer 70 is also easy to tilt from the axial direction. In addition, it is believed that if the contact area A2 is small, the contact between the elastic body 50 and the spacer 70 is unstable compared with the case where the contact area A2 is large, and the spacer 70 (especially its end face) is easy to tilt from the axial direction when, for example, an impact is applied to the gas sensor 1. In addition, it is believed that because the spacer 70 (especially its end face) is tilted from the axial direction, the ceramic housing 60 in contact with the spacer 70 (especially its end face on the front end side) is also easy to tilt from the axial direction. Therefore, the inventor of the present invention verified the range of the contact area A2 between the spacer 70 and the elastic body 50 that is effective for preventing the ceramic housing 60 from being fixed in a state tilted from the axial direction. The inventors of the present invention have confirmed that by setting the contact area A2 to 25% or more of the entire area of ​​the end surface on the front end side of the elastic body 50 , the ceramic housing 60 can be significantly prevented from being fixed in a state tilted from the axial direction, compared with a case where the contact area A2 is less than 25%.

[0142] In the gas sensor 1 , the area of ​​the portion of the front end surface of the elastic body 50 that contacts the spacer 70 , that is, the contact area A2 described above, is 25% or more of the entire area of ​​the front end surface of the elastic body 50 .

[0143] Therefore, the gas sensor 1 can significantly prevent the ceramic case 60 from being fixed in a state tilted from the axial direction, compared with a case where the contact area A2 is smaller than 25% of the entire area of ​​the front end surface of the elastic body 50 .

[0144] Here, as described above, the gas sensor 1 is manufactured through, for example, a riveting process. In the riveting process, the elastomer 50 may be deformed, and stress is generated in the direction inclined from the axial direction for the spacer 70. For example, in the riveting process, the front end face of the elastomer 50 may be pushed out to the front end side in the axial direction in a state inclined from the axial direction, and stress in the direction inclined from the axial direction is applied to the spacer 70. At the time of the riveting process, if the contact area A2 between the spacer 70 and the elastomer 50 is small, the spacer 70 is unstable because the elastomer 50 is soft. In addition, stress is generated in the direction inclined from the axial direction from the elastomer 50 toward the spacer 70, so that the spacer 70 is easy to tilt from the axial direction. In addition, because the spacer 70 (especially its front end face) is inclined from the axial direction, the ceramic shell 60 in contact with the spacer 70 may also tilt from the axial direction.

[0145] Therefore, for example, during the above-mentioned riveting process, the gas sensor 1 can prevent the ceramic housing 60 from tilting from the axial direction by sufficiently ensuring the contact area A2 between the spacer 70 and the elastic body 50 in advance. Specifically, during the riveting process, by making the contact area A2 more than 25% of the entire area of ​​the front end surface of the elastic body 50, the gas sensor 1 can prevent the occurrence of the situation that "the ceramic housing 60 tilts from the axial direction during the riveting process".

[0146] like Figure 2 As illustrated in , in the gas sensor 1, the elastic body 50 and the spacer 70 are in contact on a straight line obtained by extending the axis of the sensor element 10 (gas sensor 1) in the axial direction (that is, the extension line of the axis). In particular, in the gas sensor 1, the distance L2 from the position of the center of gravity CG2 of "the portion of the elastic body 50 (especially its front end surface) in contact with the spacer 70 (especially its rear end surface)" to the position of the extension line of the axis of the sensor element 10 is within 2 mm. The center of gravity CG2 is: the center of mass when the mass is evenly distributed in the portion of the front end surface of the elastic body 50 in contact with the spacer 70 (especially the rear end surface of the spacer 70). It should be noted that in the gas sensor 1, it is not necessary to make the distance L2 within 2 mm, and the distance L2 can be greater than 2 mm.

[0147] The inventors of the present invention believe that in order to prevent the ceramic shell 60 from being fixed in a state tilted from the axial direction, it is effective to make the elastomer 50 and the spacer 70 contact on the extension line of the axis of the sensor element 10 (gas sensor 1). In particular, it is believed that if the distance L2 from the center of gravity CG2 of the contact surface between the elastomer 50 and the spacer 70 to the extension line of the axis can be made sufficiently small, the ceramic shell 60 can be effectively prevented from being fixed in a state tilted from the axial direction. Therefore, the inventors of the present invention verified the distance L2 from the center of gravity CG2 to the extension line of the axis that is effective for preventing the ceramic shell 60 from being fixed in a state tilted from the axial direction. As a result, the inventors of the present invention confirmed that by making the distance L2 from the center of gravity CG2 to the extension line of the axis within 2 mm, the ceramic shell 60 can be significantly prevented from being fixed in a state tilted from the axial direction compared to the case where the distance L2 is greater than 2 mm.

[0148] In the gas sensor 1 , a distance L2 from the position of the center of gravity CG2 of the portion of the elastic body 50 in contact with the spacer 70 to the extension line of the axis of the sensor element 10 (gas sensor 1 ) is within 2 mm.

[0149] Therefore, the gas sensor 1 exhibits an effect of significantly preventing the ceramic case 60 from being fixed in a state tilted from the axial direction, compared with a case where the distance L2 from the center of gravity CG2 to the extension line of the axis is larger than 2 mm.

[0150] Here, as described above, the gas sensor 1 is manufactured through, for example, the above-mentioned riveting process. However, in the riveting process, the elastic body 50 is deformed, and stress is generated in a direction inclined from the axial direction from the elastic body 50 toward the spacer 70. As a result, the ceramic housing 60 in contact with the spacer 70 may also be inclined from the axial direction.

[0151] Therefore, for example, during the riveting process, by making the elastic body 50 and the spacer 70 contact on the extension line of the axis, the gas sensor 1 can prevent the ceramic housing 60 from tilting from the axial direction. Specifically, during the riveting process, the distance L2 from the center of gravity CG2 to the extension line of the axis is within 2 mm. Accordingly, the gas sensor 1 can prevent the occurrence of a situation in which "the ceramic housing 60 is positioned in a state tilted from the axial direction during the riveting process".

[0152] It should be explained that Figure 1 and Figure 2 In the gas sensor 1 illustrated in FIG. 2 , the rear end surface of the spacer 70 and the front end surface of the elastic body 50 have the same area and shape, that is, the areas and shapes of both are substantially equal.

[0153] By making the area and shape of the rear end face of the spacer 70 and the front end face of the elastic body 50 substantially equal (identical), the gas sensor 1 can achieve the following effects. That is, when the rear end face of the spacer 70 and the front end face of the elastic body 50 are identical, it is easier to make the two contact each other on the extension line of the axis of the sensor element 10, for example, in the manufacturing stage of the gas sensor 1, compared with the case where the two are different. In particular, by making the rear end face of the spacer 70 and the front end face of the elastic body 50 identical, it is easier to make the distance L2 from the center of gravity CG2 of the contact portion of the two to the extension line of the axis of the sensor element 10 smaller (for example, within 2 mm) in the manufacturing stage, etc. The rear end face of the spacer 70 and the front end face of the elastic body 50 are "identical" means that, for example, the difference in area between the two is less than about 40% of the area of ​​at least one of the rear end face of the spacer 70 and the front end face of the elastic body 50.

[0154] However, in the gas sensor 1, it is not necessary to make the rear end face of the spacer 70 identical to the front end face of the elastic body 50. For example, it is not necessary to make the area and shape of the rear end face of the spacer 70 and the front end face of the elastic body 50 substantially equal. In the gas sensor according to one embodiment of the present invention, the rear end face of the spacer and the front end face of the elastic body may be identical or different from each other.

[0155] For example, in the gas sensor 1, the rear end face of the spacer 70 may be larger than the front end face of the elastic body 50. By making the rear end face of the spacer 70 larger than the front end face of the elastic body 50, the gas sensor 1 can achieve the following effects. That is, when the rear end face of the spacer 70 is larger than the front end face of the elastic body 50, it is easier to fully ensure the contact area A2 between the two, for example, in the manufacturing stage of the gas sensor 1, compared with the case where the rear end face of the spacer 70 is smaller than the front end face of the elastic body 50. Specifically, when the rear end face of the spacer 70 is larger than the front end face of the elastic body 50, it is easier to make the contact area A2 between the two 25% or more of the entire area of ​​the front end face of the elastic body, compared with the case where the rear end face of the spacer 70 is smaller than the front end face of the elastic body 50.

[0156] In addition, in the gas sensor 1, the rear end surface of the spacer 70 may be smaller than the front end surface of the elastic body 50. However, as described above, the contact area A2 between the spacer 70 and the elastic body 50 is preferably 25% or more of the entire area of ​​the front end surface of the elastic body 50. In addition, it is desirable to make the distance L2 from the center of gravity CG2 of the contact surface between the elastic body 50 and the spacer 70 to the extension line of the axis sufficiently small, and specifically, it is desirable to make the distance L2 within 2 mm.

[0157] (Regarding the direction of the end faces of the ceramic housing, the spacer, and the elastic body)

[0158] In the gas sensor 1, the ceramic shell 60 is arranged along the axial direction, that is, the ceramic shell 60 is arranged inside the cylindrical body 20 (outer cylinder 22) in a state of extending along the axial direction. While the ceramic shell 60 is arranged along the axial direction, for example, the rear end surface of the ceramic shell 60 is orthogonal to the axial direction. In addition, in the gas sensor 1, it is preferred that the front end surface of the spacer 70 that contacts the rear end surface of the ceramic shell 60 is also orthogonal to the axial direction.

[0159] In addition to the rear end surface of the ceramic case 60 , the front end surface of the spacer 70 is also orthogonal to the axial direction. Therefore, even when an impact is applied to the gas sensor 1 , the gas sensor 1 can more effectively prevent the ceramic case 60 from tilting from the axial direction.

[0160] While the front end face of the spacer 70 is orthogonal to the axial direction, the spacer 70 is preferably arranged along the axial direction, and in the gas sensor 1, the rear end face of the spacer 70 is preferably orthogonal to the axial direction. Similarly, in the gas sensor 1, the front end face of the elastic body 50 that is preferably in contact with the spacer 70 (especially its rear end face) is also orthogonal to the axial direction. The front end face of the elastic body 50 and the rear end face and the front end face of the spacer 70 are all orthogonal to the axial direction, whereby the gas sensor 1 exerts the following effects. That is, for example, even in the case where an impact is applied to the gas sensor 1, the gas sensor 1 can extremely effectively prevent the ceramic housing 60 from tilting from the axial direction.

[0161] <Consideration on the structure of the spacer>

[0162] As described above, the gas sensor involved in one aspect of the present invention utilizes the following structure to solve the problem of the conventional gas sensor in which "the ceramic shell is sunk into the elastic body arranged on the rear end side of the ceramic shell in a state inclined from the axial direction." That is, the gas sensor involved in one aspect of the present invention solves the above-mentioned problem of the conventional gas sensor by configuring a spacer on the rear end side of the ceramic shell, especially a spacer whose front end portion including the front end surface is sufficiently hard. Specifically, the gas sensor involved in one aspect of the present invention solves the above-mentioned problem of the conventional gas sensor by configuring a spacer "whose front end portion has a Young's modulus of 80 GPa or more" on the rear end side of the ceramic shell.

[0163] Therefore, in the gas sensor according to one aspect of the present invention, the Young's modulus of the front end portion of the spacer disposed on the rear end side of the ceramic shell (i.e., the rear end face of the ceramic shell contacts) including at least the front end face thereof is 80 GPa or more. Figure 1 and Figure 2 In the gas sensor 1 described above, the entire Young's modulus of the spacer 70 disposed on the rear end side of the ceramic case 60 (that is, in contact with the rear end surface of the ceramic case 60 ) is 80 GPa or more.

[0164] However, for the gas sensor involved in one aspect of the present invention, it is not necessary for the "whole" Young's modulus of the spacer arranged on the rear end side of the ceramic shell to be 80 GPa or more. As described above, in the gas sensor involved in one aspect of the present invention, the Young's modulus of at least the front end portion including the front end surface of the spacer arranged on the rear end side of the ceramic shell can be 80 GPa or more. For example, in the gas sensor involved in one aspect of the present invention, the spacer arranged on the rear end side of the ceramic shell can be: the front end side is harder, and the rear end side is soft. In the following, using Figure 3 , a gas sensor according to one aspect of the present invention including a spacer “arranged on the rear end side of a ceramic housing and having a hard front end side and a soft rear end side” is described.

[0165] Figure 3 1 is a cross-sectional schematic diagram schematically showing an example of the main structure of a gas sensor 1A according to Modification 1. Figure 3 The left and right directions of the paper are 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. The gas sensor 1A has a spacer 70A that is "arranged on the rear end side of the ceramic housing 60 and has a hard front end side and a soft rear end side". Figure 3 The gas sensor 1A illustrated in FIG. 1 is provided with a spacer 70A instead of the spacer 70, and is different from the gas sensor 1A using Figure 1, Figure 2 The gas sensor 1 described above is the same. Therefore, in the following description, detailed description of the configuration other than the “spacer 70A” will be omitted.

[0166] like Figure 3 As illustrated in , in the gas sensor 1A, the spacer 70A includes a front end portion 71A and a rear end portion 72A. The spacer 70A is arranged inside the cylindrical body 20 (outer cylinder 22) in such a manner that the front end portion 71A is arranged on the front end side in the axial direction and the rear end portion 72A is arranged on the rear end side in the axial direction. The hardness (softness) of the front end portion 71A and the rear end portion 72A are different from each other, specifically, the Young's modulus is different from each other. That is, the Young's modulus of the front end portion 71A is greater than 80 GPa, while the Young's modulus of the rear end portion 72A is less than 80 GPa.

[0167] Figure 1 , Figure 2 , an example of a gas sensor 1 in which the spacer 70 is provided as one component is shown. Figure 3 In the gas sensor 1A illustrated in the figure, the spacer 70A arranged on the rear end side of the ceramic shell 60 is composed of a plurality of components (constituent parts). In the gas sensor involved in one aspect of the present invention, the spacer arranged on the rear end side of the ceramic shell may be composed of a plurality of components (constituent parts), and the Young's modulus of at least the front end portion may be greater than 80 GPa. In the gas sensor involved in one aspect of the present invention, the spacer may have a front end side portion of the spacer arranged on the front end side in the axial direction and a rear end side portion of the spacer arranged on the rear end side, and the Young's moduli of the two are different from each other. In the gas sensor involved in one aspect of the present invention, the spacer may be provided as a multi-stage structure (for example, a two-stage structure) including the above-mentioned front end side portion of the spacer and the rear end side portion of the spacer. For example, Figure 3 The spacer 70A illustrated in the figure has a two-stage structure including a front end portion 71A disposed at the front end side in the axial direction and a rear end portion 72A disposed at the rear end side. It should be noted that it is not essential to have the spacer 70A have a two-stage structure, and the spacer 70A may further include an intermediate portion between the front end portion 71A and the rear end portion 72A, that is, may have a three-stage or more structure.

[0168] In the gas sensor 1A, the ceramic shell 60 contacts the spacer 70A arranged on the rear end side of the ceramic shell 60, specifically, the front end surface of the spacer 70A (particularly the front end portion 71A). In the spacer 70A, the Young's modulus of the front end portion 71A including the front end surface contacted by the ceramic shell 60 (particularly the rear end surface of the ceramic shell 60) is 80 GPa or more. By making the Young's modulus of the front end portion 71A of the spacer 70A including the front end surface contacted by the ceramic shell 60 be 80 GPa or more, the gas sensor 1A exerts the following effect. That is, the gas sensor 1A exerts the following effect: it is possible to prevent the ceramic shell 60 from sinking into the component (that is, the spacer 70A) arranged on the rear end side of the ceramic shell 60 in a state tilted from the axial direction.

[0169] As described above, the spacer 70A includes the front end portion 71A including the front end surface of the spacer 70A, and the rear end portion 72A including the rear end surface of the spacer 70A. In the spacer 70A, the rear end portion 72A is softer than the front end portion 71A, and specifically, the Young's modulus of the rear end portion 72A is smaller than the Young's modulus of the front end portion 71A. That is, the Young's modulus of the front end portion 71A is 80 GPa or more, while the Young's modulus of the rear end portion 72A is less than 80 GPa.

[0170] That is, in the gas sensor 1A, the rear end portion 72A of the spacer 70A is softer and more easily bendable than the front end portion 71A of the spacer 70A. In addition, in the gas sensor 1A, the rear end surface of the spacer 70A contacts the elastic body 50 (particularly the front end surface of the elastic body 50).

[0171] Therefore, in the gas sensor 1A, even if the front end surface of the elastic body 50 is tilted relative to the axial direction, the tilt of the front end surface of the elastic body 50 can be absorbed by the rear end portion 72A of the spacer 70A. That is, in the gas sensor 1A, the soft rear end portion 72A of the spacer 70A in contact with the front end surface of the elastic body 50 is bent, so that the tilt of the front end surface of the elastic body 50 can be absorbed by the rear end portion 72A of the spacer 70A.

[0172] The spacer 70A prevents "the inclination of the front end face of the elastomer 50 from being transmitted to the ceramic shell 60 via the spacer 70A, causing the ceramic shell 60 to tilt in the axial direction" by means of the rear end portion 72A which is softer and more easily bent than the front end portion 71A. For example, in a case where the front end face of the elastomer 50 is tilted in the axial direction, stress in the direction tilted in the axial direction is sometimes transmitted from the front end face of the elastomer 50 toward the ceramic shell 60, causing the ceramic shell 60 to tilt in the axial direction due to this stress. The spacer 70A prevents the above situation by means of the rear end portion 72A which is softer and more easily bent than the front end portion 71A. That is, the spacer 70A absorbs the stress in the direction tilted in the axial direction from the front end face of the elastomer 50 by means of the rear end portion 72A, thereby preventing the ceramic shell 60 from tilting in the axial direction due to this stress. Furthermore, the front end portion 71A of the spacer 70A has sufficient hardness to significantly prevent the ceramic shell 60 from sinking into the spacer 70A.

[0173] Therefore, the gas sensor 1A can more effectively prevent the ceramic case 60 from sinking into the component (that is, the spacer 70A) disposed on the rear end side of the ceramic case 60 in a state tilted from the axial direction.

[0174] When the spacer 70A is used to suppress the temperature rise of the elastic body 50 when the gas sensor 1A is used, the front end portion 71A and the rear end portion 72A can be respectively configured as follows. That is, as the material of the front end portion 71A arranged on the front end side in the axial direction, ceramics with a higher melting point than resin are selected from the point of having better heat resistance than the rear end portion 72A. 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 rear end portion 72A 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 rear end portion 72A 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.

[0175] That is, in the gas sensor 1A, at least a part of the spacer 70A is made of ceramic, for example, the front end portion 71A of the spacer 70A is made of ceramic. Ceramics have excellent heat resistance and generally have a higher melting point than resin. In addition, in the gas sensor 1A, the spacer 70A is arranged on the front end side of the elastic body 50 in the axial direction, and in particular, the front end portion 71A of the spacer 70A is arranged on the front end side of the rear end portion 72A in the axial direction. By using ceramic having excellent heat resistance to constitute the front end portion 71A of the spacer 70A, the gas sensor 1A exerts the following effect. That is, the gas sensor 1A exerts the following effect: it is possible to prevent the front end portion 71A of the spacer 70A from being melted due to the heat emitted from the heat source located at the front end side of the gas sensor 1A. However, it is not necessary for the gas sensor 1A to use ceramic to constitute the front end portion 71A of the spacer 70A, and the gas sensor 1A can appropriately use a raw material having heat resistance as the material of the front end portion 71A of the spacer 70A.

[0176] In the gas sensor 1A, the contact area A1 (A) between the spacer 70A (particularly the tip portion 71A) and the ceramic housing 60 is 3 mm, similar to the contact area A1 in the gas sensor 1. 2 By setting the contact area A1 (A) between the spacer 70A (especially its front end surface) and the ceramic housing 60 (especially its rear end surface) to 3 mm 2 As described above, the gas sensor 1A exhibits the following effects similarly to the gas sensor 1. That is, the gas sensor 1A exhibits the following effects: the contact area A1 (A) between the spacer 70A and the ceramic case 60 is smaller than 3 mm. 2 Compared with the case where the ceramic housing 60 is fixed in a state tilted from the axial direction, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0177] In the gas sensor 1A, the area of ​​the portion of the front end surface of the elastic body 50 that contacts the spacer 70A (particularly the rear end portion 72A) (contact area A2(A)) is equal to or greater than 25% of the entire area of ​​the front end surface of the elastic body 50, similar to the contact area A2 in the gas sensor 1. By making the contact area A2(A) between the elastic body 50 (particularly the front end surface thereof) and the spacer 70A (particularly the rear end surface thereof) equal to or greater than 25% of the entire area of ​​the front end surface of the elastic body 50, the gas sensor 1A exhibits the following effect, similar to the gas sensor 1. That is, the gas sensor 1A exhibits the effect that, compared with the case where the contact area A2(A) is less than 25% of the entire area of ​​the front end surface of the elastic body 50, the ceramic housing 60 can be significantly prevented from being fixed in a state tilted from the axial direction.

[0178] In the gas sensor 1A, the distance L1(A) from the position of the center of gravity CG1(A) of the portion of the spacer 70A in contact with the ceramic shell 60 to the extension line of the axis of the sensor element 10 (gas sensor 1) is within 2 mm, similarly to the distance L1 in the gas sensor 1. The center of gravity CG1(A) is the center of mass when the mass is evenly distributed in the portion in contact with the ceramic shell 60 (particularly the rear end surface of the ceramic shell 60) at the front end surface of the spacer 70A (particularly the front end portion 71A). By making the distance L1(A) from the position of the center of gravity CG1(A) of the portion of the spacer 70A in contact with the ceramic shell 60 to the extension line of the axis of the sensor element 10 within 2 mm, the gas sensor 1A can achieve the following effects, similarly to the gas sensor 1. That is, the gas sensor 1A can significantly prevent the ceramic case 60 from being fixed in a state tilted from the axial direction, compared with a case where the distance L1 (A) from the center of gravity CG1 (A) to the extension line of the axis of the sensor element 10 is greater than 2 mm.

[0179] In the gas sensor 1A, the distance L2(A) from the position of the center of gravity CG2(A) of the portion of the elastic body 50 in contact with the spacer 70A to the extension line of the axis of the sensor element 10 (gas sensor 1) is within 2 mm. The center of gravity CG2(A) is the center of mass when the mass is evenly distributed in the portion of the front end surface of the elastic body 50 in contact with the spacer 70A (particularly the rear end surface of the spacer 70A). By making the distance L2(A) from the position of the center of gravity CG2(A) of the portion of the elastic body 50 in contact with the spacer 70A to the extension line of the axis of the sensor element 10 within 2 mm, the gas sensor 1A exerts the following effect in the same manner as the gas sensor 1. That is, the gas sensor 1A exerts the following effect: compared with the case where the distance L2(A) from the center of gravity CG2(A) to the extension line of the axis of the sensor element 10 is greater than 2 mm, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0180] In the gas sensor 1A, the material of the elastic body 50 is fluororubber like the elastic body 50 in the gas sensor 1. Therefore, the gas sensor 1A has the same effects as the gas sensor 1: for example, the sealing property of the elastic body 50 can be ensured even in a high temperature environment to maintain and improve the detection accuracy of the gas concentration.

[0181] It should be explained that Figure 3 In the gas sensor 1A illustrated in FIG. 1 , the front end surface of the spacer 70A (front end portion 71A) and the rear end surface of the ceramic case 60 have the same area and shape, that is, the areas and shapes of both are substantially equal.

[0182] By making the area and shape of the front end face of the spacer 70A and the rear end face of the ceramic housing 60 substantially equal (identical), the gas sensor 1A exhibits the following effects. That is, when the front end face of the spacer 70A and the rear end face of the ceramic housing 60 are identical, it is easier to make the two contact each other on the extension line of the axis of the sensor element 10, for example, in the manufacturing stage of the gas sensor 1A, compared with the case where the two are different. In particular, by making the front end face of the spacer 70A and the rear end face of the ceramic housing 60 identical, it is easier to make the distance L1 from the center of gravity CG1 of the contact portion of the two to the extension line of the axis of the sensor element 10 smaller (for example, within 2 mm) in the manufacturing stage, for example. Here, the front end face of the spacer 70A and the rear end face of the ceramic housing 60 are "identical" means that, for example, both are circular or elliptical, and the difference in area between the two is less than about 40% of the area of ​​at least one of the two.

[0183] However, in the gas sensor 1A, it is not necessary to make the front end face of the spacer 70A identical to the rear end face of the ceramic shell 60. For example, it is not necessary to make the areas and shapes of the two substantially equal. In the gas sensor involved in one embodiment of the present invention, the front end face of the spacer and the rear end face of the ceramic shell may be identical or different.

[0184] For example, in the gas sensor 1A, the front end surface of the spacer 70A may be smaller than the rear end surface of the ceramic shell 60. Similarly, in the gas sensor 1A, the front end surface of the spacer 70A may be larger than the rear end surface of the ceramic shell 60. By making the front end surface of the spacer 70A larger than the rear end surface of the ceramic shell 60, the gas sensor 1A exerts the following effect. That is, compared with the case where the front end surface of the spacer 70A is smaller than the rear end surface of the ceramic shell 60, it is easier to fully ensure the contact area A1 (A) between the two, for example, in the manufacturing stage of the gas sensor 1A. Specifically, compared with the case where the front end surface of the spacer 70A is smaller than the rear end surface of the ceramic shell 60, it is easier to make the contact area A1 (A) 3mm in the manufacturing stage of the gas sensor 1A. 2 .

[0185] in addition, Figure 3 In the gas sensor 1A illustrated in FIG. 1 , the rear end surface of the spacer 70A and the front end surface of the elastic body 50 have the same area and shape, that is, the areas and shapes of both are substantially equal.

[0186] By making the area and shape of the rear end face of the spacer 70A and the front end face of the elastic body 50 substantially equal (identical), the gas sensor 1A exhibits the following effects. That is, when the rear end face of the spacer 70A and the front end face of the elastic body 50 are the same, it is easier to make the two contact each other on the extension line of the axis of the sensor element 10, for example, in the manufacturing stage of the gas sensor 1A, compared with the case where the two are different. In particular, by making the rear end face of the spacer 70A and the front end face of the elastic body 50 the same, it is easier to make the distance L2(A) from the center of gravity CG2(A) of the contact portion of the two to the extension line of the axis of the sensor element 10 smaller (for example, within 2 mm) in the manufacturing stage, etc. The rear end face of the spacer 70A and the front end face of the elastic body 50 are "identical" means that, for example, the difference in area between the two is less than about 40% of the area of ​​at least one of the rear end face of the spacer 70A and the front end face of the elastic body 50.

[0187] However, in the gas sensor 1A, it is not essential to make the rear end face of the spacer 70A and the front end face of the elastic body 50 identical. For example, it is not essential to make the area and shape of the rear end face of the spacer 70A and the front end face of the elastic body 50 substantially equal. In the gas sensor according to one embodiment of the present invention, the rear end face of the spacer and the front end face of the elastic body may be identical or different.

[0188] For example, in the gas sensor 1A, the rear end face of the spacer 70A may be larger than the front end face of the elastic body 50. By making the rear end face of the spacer 70A larger than the front end face of the elastic body 50, the gas sensor 1A exerts the following effects. That is, when the rear end face of the spacer 70A is larger than the front end face of the elastic body 50, it is easier to fully ensure the contact area A2(A) between the two, for example, in the manufacturing stage of the gas sensor 1A, compared with the case where the rear end face of the spacer 70A is smaller than the front end face of the elastic body 50. Specifically, when the rear end face of the spacer 70A is larger than the front end face of the elastic body 50, it is easier to make the contact area A2(A) between the two 25% or more of the entire area of ​​the front end face of the elastic body, compared with the case where the rear end face of the spacer 70A is smaller than the front end face of the elastic body 50.

[0189] In the gas sensor 1A, the rear end surface of the spacer 70A may be smaller than the front end surface of the elastic body 50. However, as described above, the contact area A2(A) between the spacer 70A and the elastic body 50 is preferably 25% or more of the entire area of ​​the front end surface of the elastic body 50. In addition, it is desirable to make the distance L2(A) from the center of gravity CG2(A) of the contact surface between the elastic body 50 and the spacer 70A to the extension line of the axis sufficiently small, and specifically, it is desirable to make the distance L2(A) within 2 mm.

[0190] (Regarding the direction of the end faces of the ceramic housing, the spacer, and the elastic body)

[0191] In the gas sensor 1A, the ceramic shell 60 is arranged along the axial direction, that is, the ceramic shell 60 is arranged inside the cylindrical body 20 (outer cylinder 22) in a state of extending in the axial direction. While the ceramic shell 60 is arranged along the axial direction, for example, the rear end surface of the ceramic shell 60 is orthogonal to the axial direction. In addition, in the gas sensor 1A, the front end surface of the spacer 70A (particularly the front end portion 71A) that contacts the rear end surface of the ceramic shell 60 is also preferably orthogonal to the axial direction.

[0192] In addition to the rear end surface of the ceramic housing 60, the front end surface of the spacer 70A (particularly the front end portion 71A) is also orthogonal to the axial direction, so that the gas sensor 1A exerts the following effect. That is, in the gas sensor 1A, for example, even in a situation where an impact is applied to the gas sensor 1A, the ceramic housing 60 can be more effectively suppressed from tilting from the axial direction.

[0193] It should be noted that, as described above, in the spacer 70A, the rear end portion 72A is softer than the front end portion 71A, that is, the rear end portion 72A is more easily bent than the front end portion 71A. Therefore, even if the front end face of the elastic body 50 is tilted in a direction orthogonal to the axial direction, the spacer 70A can absorb the tilt of the front end face of the elastic body 50 by bending the rear end portion 72A, thereby preventing the spacer 70A (especially its front end face) from tilting in the axial direction. In addition, in the gas sensor 1A, by preventing the spacer 70A (especially its front end face) from tilting in the axial direction, the ceramic housing 60 can be prevented from tilting in the axial direction. Therefore, in the gas sensor 1A, the rear end face of the spacer 70A (rear end portion 72A) may not be orthogonal to the axial direction. However, in the gas sensor 1A, the rear end face of the spacer 70A may be orthogonal to the axial direction. Similarly, in the gas sensor 1A, the front end face of the elastic body 50 in contact with the spacer 70A (especially its rear end face) may not be orthogonal to the axial direction, or may be orthogonal to the axial direction.

[0194] <Consideration on the shape of the spacer>

[0195] The gas sensors 1 and 1A described above both include a spacer that is disposed on the rear end side of the ceramic case 60 , has a hard front end side (specifically, Young's modulus of 80 GPa or more), and has a front end surface that is flush with the rear end surface of the ceramic case.

[0196] By making the front end face of the spacer the same as the rear end face of the ceramic shell, for example, making the area and shape of the front end face of the spacer and the rear end face of the ceramic shell approximately equal, the gas sensor involved in one embodiment of the present invention exerts the following effect. That is, when the front end face of the spacer and the rear end face of the ceramic shell are the same, it is easier to make the two contact each other on the extension line of the axis of the sensor element (gas sensor) in the manufacturing stage of the gas sensor, for example, compared with the case where the two are different. In particular, by making the area and shape of the front end face of the spacer and the rear end face of the ceramic shell approximately equal, it is easier to make the "distance from the center of gravity of the contact portion of the two to the extension line of the axis of the sensor element 10" smaller (for example, within 2 mm) in the manufacturing stage, for example.

[0197] However, in the gas sensor involved in one embodiment of the present invention, it is not necessary for the front end face of the spacer and the rear end face of the ceramic shell to be the same. For example, it is not necessary for the areas and shapes of the two to be roughly equal. In the gas sensor involved in one embodiment of the present invention, the front end face of the spacer and the rear end face of the ceramic shell may be the same, or the two may be different. In the gas sensor involved in one aspect of the present invention, the Young's modulus of the front end portion of the spacer arranged on the rear end side of the ceramic shell (that is, in contact with the rear end face of the ceramic shell) including at least its front end face is 80 GPa or more. In the gas sensor involved in one aspect of the present invention, the shape of the spacer "arranged on the rear end side of the ceramic shell 60 and with a harder front end side" is not particularly limited. For example, its front end face may be larger than the rear end face of the ceramic shell. Below, as a gas sensor involved in one aspect of the present invention, a Figure 4 , an example of a gas sensor including a spacer having a front end surface larger than a rear end surface of a ceramic housing 60 and a front end portion including the front end surface having a Young's modulus of 80 GPa or more is described.

[0198] 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 4 , 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. The gas sensor 1B has a spacer 70B whose "front end surface is larger than the rear end surface of the ceramic housing 60, and the Young's modulus of the front end portion including the front end surface is 80 GPa or more". Figure 4 The gas sensor 1B illustrated in FIG. 1 is provided with a spacer 70B instead of the spacer 70, and is different from the gas sensor 1B using Figure 1 , Figure 2 The gas sensor 1 described above is the same. Therefore, in the following description, detailed description of the configuration other than the “spacer 70B” will be omitted.

[0199] In the gas sensor 1B, the front end surface of the spacer 70B is larger than the rear end surface of the ceramic shell 60 that contacts the front end surface of the spacer 70B. In the gas sensor according to one embodiment of the present invention, it is not necessary to make the front end surface of the spacer arranged on the rear end side of the ceramic shell and the rear end surface of the ceramic shell have the same area and shape.

[0200] By making the front end surface of the spacer 70B larger than the rear end surface of the ceramic shell 60, the gas sensor 1B achieves the following effects. That is, when the front end surface of the spacer 70B is larger than the rear end surface of the ceramic shell 60, it is easier to fully ensure the contact area A1(B) between the two, for example, in the manufacturing stage of the gas sensor 1B, compared with the case where the front end surface of the spacer 70B is smaller than the rear end surface of the ceramic shell 60. Specifically, when the front end surface of the spacer 70B is larger than the rear end surface of the ceramic shell 60, it is easier to make the contact area A1(B) 3mm in the manufacturing stage of the gas sensor 1B, compared with the case where the front end surface of the spacer 70B is smaller than the rear end surface of the ceramic shell 60. 2 .

[0201] In the gas sensor 1B, the ceramic shell 60 contacts the spacer 70B arranged on the rear end side of the ceramic shell 60, specifically, the front end face of the spacer 70B. In the spacer 70B, the Young's modulus of the front end portion including the front end face contacted by the ceramic shell 60 (especially the rear end face of the ceramic shell 60) is 80 GPa or more. That is, in the gas sensor 1B, the Young's modulus of the spacer 70B as a whole is 80 GPa or more, that is, the Young's modulus of the whole including the front end portion is 80 GPa or more. By making the Young's modulus of the spacer 70B as a whole, especially the Young's modulus of the front end portion including the front end face contacted by the spacer 70B including the front end face of the ceramic shell 60 to be 80 GPa or more, the gas sensor 1B exerts the following effect. That is, the gas sensor 1B exerts the following effect: it is possible to prevent the ceramic shell 60 from sinking into the component (that is, the spacer 70B) arranged on the rear end side of the ceramic shell 60 in a state tilted from the axial direction.

[0202] In the gas sensor 1B, the contact area A1 (B) between the spacer 70B (particularly the front end surface of the spacer 70B) and the ceramic housing 60 (particularly the rear end surface of the ceramic housing 60) is 3 mm, similar to the contact area A1 in the gas sensor 1. 2 By setting the contact area A1 (B) between the spacer 70B (especially its front end surface) and the ceramic housing 60 (especially its rear end surface) to 3 mm 2 As described above, the gas sensor 1B exhibits the following effects similarly to the gas sensor 1. That is, the gas sensor 1B exhibits the following effects: the contact area A1 (B) between the spacer 70B and the ceramic case 60 is smaller than 3 mm. 2Compared with the case where the ceramic housing 60 is fixed in a state tilted from the axial direction, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0203] In the gas sensor 1B, the area of ​​the portion of the front end surface of the elastic body 50 that contacts the spacer 70B (particularly the rear end surface thereof) (contact area A2(B)) is equal to or greater than 25% of the entire area of ​​the front end surface of the elastic body 50, similar to the contact area A2 in the gas sensor 1. By making the contact area A2(B) between the elastic body 50 (particularly the front end surface thereof) and the spacer 70B (particularly the rear end surface thereof) equal to or greater than 25% of the entire area of ​​the front end surface of the elastic body 50, the gas sensor 1B exhibits the following effect, similar to the gas sensor 1. That is, the gas sensor 1B exhibits the following effect: compared with the case where the contact area A2(B) is less than 25% of the entire area of ​​the front end surface of the elastic body 50, the ceramic housing 60 can be significantly prevented from being fixed in a state tilted from the axial direction.

[0204] In the gas sensor 1B, the distance L1(B) from the position of the center of gravity CG1(B) of the portion of the spacer 70B in contact with the ceramic shell 60 to the extension line of the axis of the sensor element 10 (gas sensor 1) is within 2 mm, similarly to the distance L1 in the gas sensor 1. The center of gravity CG1(B) is the center of mass when the mass is evenly distributed in the portion of the front end surface of the spacer 70B in contact with the ceramic shell 60 (particularly the rear end surface of the ceramic shell 60). By making the distance L1(B) from the position of the center of gravity CG1(B) of the portion of the spacer 70B in contact with the ceramic shell 60 to the extension line of the axis of the sensor element 10 within 2 mm, the gas sensor 1B exhibits the following effect similarly to the gas sensor 1. That is, the gas sensor 1B exhibits the following effect: compared with the case where the distance L1(B) from the center of gravity CG1(B) to the extension line of the axis of the sensor element 10 is greater than 2 mm, the ceramic shell 60 can be significantly prevented from being fixed in a state tilted from the axial direction.

[0205] In the gas sensor 1B, the distance L2(B) from the position of the center of gravity CG2(B) of the portion of the elastic body 50 in contact with the spacer 70B to the extension line of the axis of the sensor element 10 (gas sensor 1) is within 2 mm. The center of gravity CG2(B) is the center of mass when the mass is evenly distributed in the portion of the front end surface of the elastic body 50 in contact with the spacer 70B (particularly the rear end surface of the spacer 70B). By making the distance L2(B) from the position of the center of gravity CG2(B) of the portion of the elastic body 50 in contact with the spacer 70B to the extension line of the axis of the sensor element 10 within 2 mm, the gas sensor 1B exerts the following effect in the same manner as the gas sensor 1. That is, the gas sensor 1B exerts the following effect: compared with the case where the distance L2(B) from the center of gravity CG2(B) to the extension line of the axis of the sensor element 10 is greater than 2 mm, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state tilted from the axial direction.

[0206] In the gas sensor 1B, the material of the elastic body 50 is fluororubber like the elastic body 50 in the gas sensor 1. Therefore, the gas sensor 1B has the same effects as the gas sensor 1: for example, the sealing property of the elastic body 50 can be ensured even in a high temperature environment to maintain and improve the detection accuracy of the gas concentration.

[0207] In the gas sensor 1B, at least a portion of the spacer 70B is made of ceramics, and specifically, the spacer 70B is entirely made of ceramics. Ceramics have excellent heat resistance and generally have a higher melting point than resins. Furthermore, in the gas sensor 1B, the spacer 70B is arranged to be closer to the front end side than the elastomer 50 in the axial direction. By using ceramics having excellent heat resistance to constitute the spacer 70B, the gas sensor 1B exerts the following effect. That is, the gas sensor 1B exerts the following effect: it is possible to prevent the spacer 70B from being melted due to heat emitted from a heat source located on the front end side of the gas sensor 1B. However, it is not necessary for the gas sensor 1B to use ceramics to constitute the spacer 70B, and the gas sensor 1B can appropriately use heat-resistant raw materials for the material of the spacer 70B.

[0208] Figure 4 In the gas sensor 1B illustrated in FIG. 1 , the rear end surface of the spacer 70B and the front end surface of the elastic body 50 have the same area and shape, that is, the areas and shapes of both are substantially equal.

[0209] By making the area and shape of the rear end face of the spacer 70B and the front end face of the elastic body 50 substantially equal (identical), the gas sensor 1B exhibits the following effects. That is, when the rear end face of the spacer 70B and the front end face of the elastic body 50 are identical, it is easier to make the two contact each other on the extension line of the axis of the sensor element 10, for example, in the manufacturing stage of the gas sensor 1B, compared with the case where the two are different. In particular, by making the rear end face of the spacer 70B and the front end face of the elastic body 50 identical, it is easier to make the distance L2(B) from the center of gravity CG2(B) of the contact portion of the two to the extension line of the axis of the sensor element 10 smaller (for example, within 2 mm) in the manufacturing stage, etc. The rear end face of the spacer 70B and the front end face of the elastic body 50 are "identical" means that, for example, the difference in area between the two is less than about 40% of the area of ​​at least one of the rear end face of the spacer 70B and the front end face of the elastic body 50.

[0210] However, in the gas sensor 1B, it is not essential to make the rear end face of the spacer 70B and the front end face of the elastic body 50 identical. For example, it is not essential to make the area and shape of the rear end face of the spacer 70B and the front end face of the elastic body 50 substantially equal. In the gas sensor according to one embodiment of the present invention, the rear end face of the spacer and the front end face of the elastic body may be identical or different.

[0211] For example, in the gas sensor 1B, the rear end face of the spacer 70B may be larger than the front end face of the elastic body 50. By making the rear end face of the spacer 70B larger than the front end face of the elastic body 50, the gas sensor 1B exerts the following effect. That is, when the rear end face of the spacer 70B is larger than the front end face of the elastic body 50, it is easier to fully ensure the contact area A2(B) between the two, for example, in the manufacturing stage of the gas sensor 1B, compared with the case where the rear end face of the spacer 70B is smaller than the front end face of the elastic body 50. Specifically, when the rear end face of the spacer 70B is larger than the front end face of the elastic body 50, it is easier to make the contact area A2(B) between the two 25% or more of the entire area of ​​the front end face of the elastic body, compared with the case where the rear end face of the spacer 70B is smaller than the front end face of the elastic body 50.

[0212] In the gas sensor 1B, the rear end surface of the spacer 70B may be smaller than the front end surface of the elastic body 50. However, as described above, the contact area A2(B) between the spacer 70B and the elastic body 50 is preferably 25% or more of the entire area of ​​the front end surface of the elastic body 50. In addition, it is desirable to make the distance L2(B) from the center of gravity CG2(B) of the contact surface between the elastic body 50 and the spacer 70B to the extension line of the axis sufficiently small, and specifically, it is desirable to make the distance L2(B) within 2 mm.

[0213] [feature]

[0214] As described above, the gas sensor (1, 1A, 1B) involved in one aspect of the present invention comprises: a sensor element 10, a terminal metal fitting 30, a ceramic shell 60, a cylindrical body 20, an elastic body 50, and a spacer (70, 70A, 70B). The sensor element 10 extends in the axial direction, has a detection portion 11 on the front end side, and has a connector electrode 12 on the rear end side. The terminal metal fitting 30 extends in the axial direction, 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 accommodates the connector electrode 12 of the sensor element 10 and the element contact portion 31 of the terminal metal fitting 30. The cylindrical body 20 is a cylindrical component in which the sensor element 10, the terminal metal fitting 30, and the ceramic shell 60 are arranged and an open end is formed. The elastic body 50 is arranged in a manner to close the open end (the open end on the rear end side) of the cylindrical body 20.

[0215] The spacer (70, 70A, 70B) involved in one aspect of the present invention is arranged between the ceramic shell 60 and the elastomer 50 in the axial direction of the sensor element 10 (gas sensor (1, 1A, 1B)). The spacer is in contact with the ceramic shell 60 at the front end face, and in contact with the elastomer 50 at the rear end face. The Young's modulus of the front end portion of the spacer involved in one aspect of the present invention, including at least the front end face, is greater than 80 GPa. For example, the spacers 70 and 70B each have an overall Young's modulus of greater than 80 GPa. In addition, the spacer 70A includes: a front end portion 71A having a Young's modulus of greater than 80 GPa, and a rear end portion 72A having a Young's modulus less than 80 GPa.

[0216] The inventors of the present invention believe that by disposing a spacer (70, 70A, 70B) between the ceramic shell 60 and the elastic body 50, it is possible to prevent the ceramic shell 60 from sinking into the elastic body 50. Therefore, in a gas sensor according to one aspect of the present invention, a spacer (70, 70A, 70B) is disposed between the ceramic shell 60 and the elastic body 50.

[0217] The inventors of the present invention also believe that in order to prevent the ceramic shell 60 from sinking into the component arranged on the rear end side of the ceramic shell 60, it is effective to make the part of the front end side of the component arranged on the rear end side in the axial direction sufficiently hard. Here, as described above, in the gas sensor involved in one aspect of the present invention, a spacer (70, 70A, 70B) is arranged between the ceramic shell 60 and the elastomer 50. Therefore, the inventors of the present invention determined the hardness (softness) that the front end portion of the spacer should have in order to prevent the ceramic shell 60 from sinking into the spacer (70, 70A, 70B) (especially its front end portion) through experiments (embodiments described later). As a result, the inventors of the present invention confirmed that by making the Young's modulus of the front end portion of the above-mentioned spacer greater than 80 GPa, it is possible to significantly prevent the ceramic shell 60 from sinking into the spacer (especially its front end portion) compared to the case where it is less than 80 GPa.

[0218] In a gas sensor according to one aspect of the present invention, a ceramic housing 60 is in contact with a spacer (70, 70A, 70B) disposed on the rear end side of the ceramic housing 60, and in particular, in contact with the front end surface of the spacer (70, 70A, 70B). Furthermore, the Young's modulus of the front end portion of the spacer (70, 70A, 70B) including the front end surface is 80 GPa or more, and has sufficient hardness to significantly prevent the ceramic housing 60 from sinking into the spacer (particularly the front end portion thereof).

[0219] Therefore, in the gas sensor according to one aspect of the present invention, there does not occur a phenomenon in which the ceramic case 60 is sunk into the spacer disposed on the rear end side of the ceramic case 60 in a state tilted from the axial direction and is fixed in this state.

[0220] Therefore, the gas sensor according to one aspect of the present invention can prevent the ceramic housing 60 from sinking into the component (ie, the spacer ( 70 , 70A, 70B)) disposed on the rear end side of the ceramic housing 60 in a state tilted from the axial direction.

[0221] [Modifications]

[0222] 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.

[0223] In a gas sensor according to one embodiment of the present invention (e.g., the gas sensors 1, 1A, 1B described above), the shape of the spacer (70, 70A, 70B) disposed between the elastomer (50) and the ceramic shell (60) is not particularly limited. The spacer may be, for example, cylindrical, or truncated cone, or may be a shape obtained by arranging one or more cylinders and one or more truncated cones in the axial direction. In addition, the length of at least a portion of the spacer in a direction orthogonal to the axial direction (e.g., the diameter in a direction orthogonal to the axial direction) may vary continuously or discontinuously along the axial direction. Furthermore, the front end face and the rear end face of the spacer may be of substantially the same shape, the area of ​​the front end face may be smaller than the area of ​​the rear end face, or the area of ​​the front end face may be larger than the area of ​​the rear end face.

[0224] In addition, the front end face of the spacer may be the same as the rear end face of the ceramic shell, for example, the area and shape of the front end face of the spacer and the rear end face of the ceramic shell may be substantially equal. In addition, the front end face of the spacer and the rear end face of the ceramic shell may also be different from each other, that is, at least one of the area and shape of the two may be different from each other.

[0225] Similarly, the rear end face of the spacer may be the same as the front end face of the elastic body, for example, the area and shape of the rear end face of the spacer and the front end face of the elastic body may be substantially equal. In addition, the rear end face of the spacer and the front end face of the elastic body may also be different from each other, that is, at least one of the area and shape of the two may be different from each other.

[0226] [Example]

[0227] To verify the effects of the present invention (particularly the durability of the terminal metal fittings), the inventors of the present invention manufactured gas sensors of the following ranges (Examples) 1 to 4 and conducted HALT tests (Highly Accelerated limit Tests). However, the present invention is not limited to the following ranges (Examples).

[0228] Table 1

[0229]

[0230] The gas sensor of the gear position 1 is a conventional gas sensor as disclosed in the above-mentioned patent document 1 (Japanese Patent Publication No. 2014-196917), that is, a gas sensor in which a spacer is not arranged between the ceramic shell and the elastic body. Specifically, in the gas sensor of the gear position 1, an elastic body is arranged on the rear end side of the ceramic shell in the axial direction of the gas sensor (the axial direction of the sensor element), and in particular, the elastic body contacts the ceramic shell at the rear end of the ceramic shell.

[0231] The gas sensors for gears 2 to 4 are respectively Figure 1The gas sensor of the configuration (components) illustrated in the figure, that is, a gas sensor in which a spacer is arranged between a ceramic shell and an elastomer. Specifically, in the gas sensors of gears 2 to 4, a spacer is arranged on the rear end side of the ceramic shell in the axial direction, and in particular, the spacer contacts the ceramic shell at the rear end of the ceramic shell. However, in the gas sensors of gears 2 to 4, the Young's modulus of the spacer in contact with the ceramic shell at the rear end of the ceramic shell is different from each other.

[0232] That is, in the gas sensor of gear position 2, the Young's modulus of the spacer is 65 GPa, that is, the Young's modulus of the spacer in contact with the ceramic shell at the rear end of the ceramic shell is less than 80 GPa. In contrast, in the gas sensors of gear positions 3 to 4, the Young's modulus of the spacer is greater than 80 GPa, that is, the Young's modulus of the spacer in contact with the ceramic shell at the rear end of the ceramic shell is greater than 80 GPa. Specifically, in the gas sensor of gear position 3, the Young's modulus of the spacer is 80 GPa. In addition, in the gas sensor of gear position 4, the Young's modulus of the spacer is 120 GPa.

[0233] The inventors of the present invention conducted the following HALT test (Highly Accelerated limit Test) for the gas sensors of gears 1 to 4 in order to compare the durability of the terminal metal parts assembled in the ceramic housing and connected to the sensor element. That is, the gas sensors of gears 1 to 4 (multiple gas sensors of each gear) were subjected to the following HALT test (Highly Accelerated limit Test). Figure 5 The sequence shown is a HALT test in which the temperature and acceleration conditions are changed.

[0234] Figure 5 It is a graph showing changes (sequences) in temperature conditions and acceleration conditions in a HALT test (durability comparison test) conducted by the inventors of the present invention on gas sensors in each of the gears 1 to 4. Figure 5 In the curve diagram shown in FIG. 1 , the change in temperature condition is represented by a dotted line, such as Figure 5 As shown in the example, the temperature condition is changed within the range of "-90°C" to "190°C". Figure 5 In the curve diagram shown in FIG. 1 , the change of acceleration condition is represented by a solid line, such as Figure 5 As shown in the example, the acceleration condition is changed within the range of "10 Grms" to "70 Grms".

[0235] The HALT test is performed on multiple gas sensors in each gear position to confirm whether the terminal metal parts mounted on the ceramic shell are damaged after the HALT test is performed (for example, at time = 200. In other words, at the time when acceleration = 40 Grms). That is, the above-mentioned HALT test is performed on multiple gas sensors in gear position 1, and after the HALT test is performed, it is confirmed whether the terminal metal parts of each of the multiple gas sensors are damaged. Similarly, the above-mentioned HALT test is performed on multiple gas sensors in each gear position 2 to 4, and after the HALT test is performed, it is confirmed whether the terminal metal parts of each of the multiple gas sensors are damaged.

[0236] In Table 1, the evaluation of "0 (excellent)" indicates that none of the multiple gas sensors at each position had damage to the terminal metal fittings mounted on the ceramic housing. The evaluation of "× (poor)" indicates that damage to the terminal metal fittings was confirmed in more than one of the multiple gas sensors at each position.

[0237] It should be noted that in the above HALT test, temperature and acceleration (vibration) stress exceeding the actual use conditions of the gas sensors were applied to multiple gas sensors in each gear. Therefore, it should be noted that even if the evaluation in Table 1 is "× (bad)", the "×" evaluation does not mean that the gas sensor in the gear with the "×" evaluation is not suitable for actual use.

[0238] The evaluation of the conventional gas sensor of position 1 (a gas sensor in which no spacer is arranged between the ceramic shell and the elastic body) is “× (poor)”. In addition, the evaluation of the gas sensor of position 2 (a gas sensor in which a spacer is arranged between the ceramic shell and the elastic body, but the Young's modulus of the spacer is less than 80 GPa) is “× (poor)”.

[0239] In contrast, the gas sensors of gears 3 to 4 (gas sensors in which a spacer is arranged between the ceramic shell and the elastic body and the Young's modulus of the spacer is 80 GPa or more) were all evaluated as "0 (excellent)".

[0240] Therefore, the inventors of the present invention have confirmed the following phenomenon through the HALT test and its test results (evaluation) described above. That is, the inventors of the present invention have confirmed that by configuring a spacer between the ceramic housing and the elastic body and making the Young's modulus of the spacer 80 GPa or more, the possibility of damage to the terminal metal fittings assembled in the ceramic housing can be suppressed.

Claims

1. A gas sensor comprising: a sensor element extending in the axial direction, having a detection portion on the front end side and a connector electrode on the rear end side; 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 housing for housing the connector electrodes and the component contact portion; a cylindrical body, in which the sensor element, the terminal metal fitting, and the ceramic housing are arranged, and an open end is formed; an elastic body configured to close the open end; as well as A spacer is arranged between the ceramic shell and the elastomer in the axial direction, and the end face on the front end side in the axial direction is in contact with the ceramic shell, and the end face on the rear end side in the axial direction is in contact with the elastomer, and the Young's modulus of the front end portion including at least the end face on the front end side is greater than 80 GPa.

2. The gas sensor according to claim 1, wherein: In the spacer, a Young's modulus of a rear end portion including an end surface on the rear end side is smaller than a Young's modulus of the front end portion.

3. The gas sensor according to claim 1 or 2, wherein: The contact area between the spacer and the ceramic housing is 3 mm 2 above.

4. The gas sensor according to claim 1 or 2, wherein: An area of ​​a portion of the end surface on the front end side of the elastic body that contacts the spacer is equal to or greater than 25% of an entire area of ​​the end surface on the front end side of the elastic body.

5. The gas sensor according to claim 1 or 2, wherein: The distance from the center of mass when assuming that the mass is evenly distributed in the portion in contact with the ceramic shell at the end surface of the front end side of the spacer, that is, the position of the center of gravity of the portion in contact with the ceramic shell at the end surface of the front end side of the spacer, to the straight line obtained by extending the axis of the sensor element along the axial direction is within 2 mm.

6. The gas sensor according to claim 1 or 2, wherein: The distance from the center of mass when assuming that the mass is evenly distributed in the portion in contact with the spacer at the end surface on the front end side of the elastomer, that is, the position of the center of gravity of the portion in contact with the spacer at the end surface on the front end side of the elastomer, to the straight line obtained by extending the axis of the sensor element along the axial direction is within 2 mm.

7. The gas sensor according to claim 1 or 2, wherein: The material of the elastic body is fluororubber.

8. The gas sensor according to claim 1 or 2, wherein: At least a portion of the spacer is made of ceramic.

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