GAS SENSOR

Abstract

A gas sensor is provided that prevents a ceramic housing from penetrating a component that is arranged at a rear end face of the ceramic housing in a state where it is inclined from an axial direction. In the gas sensor according to one aspect of the present invention, a spacer with a Young's modulus of 80 GPa or more is arranged at least in a front end section at a rear end face of the ceramic housing, to which a connector is attached.

Description

FIELD OF THE INVENTION

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

[0002] Conventionally, a gas sensor is known that measures the concentration of a specific gas such as oxygen or NO x in a measurement gas such as the exhaust gas of an automobile. For example, JP 2014-196917 A cited below discloses a gas sensor including a tubular body in which a sensor element and a connector (ceramic case) are disposed, to which a contact piece electrically connected to the sensor element is attached, and an elastic body that seals an opening end of the tubular body. In the gas sensor disclosed in JP 2014-196917 A, an elastic body is disposed on the rear end side in an axial direction of the gas sensor (axial direction of the sensor element) of the ceramic case. SUMMARY OF THE INVENTION

[0003] The present inventors have discovered that, with the conventional gas sensor disclosed in JP 2014-196917 A, a problem arises when the ceramic housing is mounted in a state where it is inclined relative to the axial direction within the tubular body. That is, in a case where the ceramic housing is mounted in a state where it is inclined relative to the axial direction, an unintended stress (for example, a stress in a direction other than a direction orthogonal to the axial direction) acts from the sensor element to the terminal fitting attached to the ceramic housing and connected to the sensor element.For this reason, the inventors of the present invention have found a problem that in a case where the ceramic package is fixed in a state where it is inclined with respect to the axial direction in the gas sensor, when an impact is applied to the gas sensor, the terminal fitting is more likely to break than in a case where the ceramic package is fixed parallel to the axial direction.

[0004] The inventors of the present invention further investigated and found that a case where the ceramic case is fixed in a state where it is inclined from the axial direction occurs, for example, as described below. That is, in the conventional gas sensor, the elastic body that is arranged on the rear end side of the ceramic case and seals an opening end of the tubular body has a lower Young's modulus than the ceramic case, that is, it is softer than the ceramic case. For this reason, the inventors of the present invention found that the above-described event occurs when the ceramic case penetrates into an elastic body that is softer than the ceramic case in a state where it is inclined from the axial direction, for example, in a manufacturing stage of a gas sensor.

[0005] As described above, the inventors of the present invention have found a problem that when the ceramic package penetrates into a member (e.g., an elastic body) arranged on the rear end side of the ceramic package in a state where the ceramic package is inclined from the axial direction, the terminal fitting fixed to the ceramic package is easily broken.

[0006] The present invention has been made in view of such circumstances in one aspect, and an object of the present invention is to provide a gas sensor in which a ceramic case is prevented from penetrating into a member arranged on the rear end side of the ceramic case in a state of being inclined from an axial direction.

[0007] In order to solve the above-described problem, the present invention adopts the following configuration.

[0008] A gas sensor according to a first aspect includes a sensor element extending in an axial direction, having a detection unit at a front end side and a connector electrode at a rear end side, a terminal extending in the axial direction and having an element contact portion electrically connected to the connector electrode at a front end side, a ceramic case accommodating the connector electrode and the element contact portion, a tubular body in which the sensor element, the terminal, and the ceramic case are arranged and an opening end is formed, and an elastic body attached to seal the opening end;and a spacer disposed between the ceramic housing and the elastic body in the axial direction, in contact with the ceramic housing at an end surface on a front end side in the axial direction, in contact with the elastic body at an end surface on a rear end side in the axial direction, and having a Young's modulus of 80 GPa or more at least at a front end portion including an end surface on the front end side.;

[0009] In the configuration, the ceramic package in the gas sensor is in contact with the front end portion of the spacer arranged on the rear end side of the ceramic package, the front end portion having a Young's modulus of 80 GPa or more.

[0010] The inventors of the present invention believe that it is possible to prevent the ceramic housing from penetrating or seizing the elastic body by interposing the spacer between the ceramic housing and the elastic body. In view of this, the gas sensor interposes the spacer between the ceramic housing and the elastic body.

[0011] To prevent the ceramic housing from penetrating a component disposed on the rear end side of the ceramic housing, the inventors of the present invention believe it is appropriate to sufficiently harden a portion on the front end side in the axial direction of the component disposed on the rear end side. As described hereinbefore, in the gas sensor, the spacer is disposed between the ceramic housing and the elastic body. To prevent the ceramic housing from penetrating the spacer (particularly the front end portion of the spacer), the inventors of the present invention experimentally determined the hardness (softness) to be imparted to the front end portion of the spacer.As a result, the inventors of the present invention have confirmed that by setting the Young's modulus of the front end portion of the spacer to 80 GPa or more, it is possible to remarkably prevent the penetration of the ceramic package into the spacer (particularly the front end portion) compared with a case where the Young's modulus is set to less than 80 GPa.

[0012] In the gas sensor, the ceramic housing is in contact with the spacer disposed at the rear end of the ceramic housing, particularly with an end surface at the front end of the spacer. Then, the Young's modulus of the front end portion, including an end surface at the front end of the spacer, is 80 GPa or more, which is a sufficient hardness to remarkably prevent the ceramic housing from penetrating the spacer (especially the front end portion).

[0013] For this reason, in the gas sensor, an event such as “the ceramic package penetrates into the spacer arranged on the rear end side of the ceramic package in a state where it is inclined with respect to the axial direction, and such a state is fixed” does not occur.

[0014] Therefore, the gas sensor achieves the effect of being able to prevent the ceramic package from penetrating into a component (ie, the spacer) arranged on the rear end side of the ceramic package in a state where it is inclined with respect to the axial direction.

[0015] A gas sensor according to a second aspect is the gas sensor according to the first aspect, in which, in the spacer, the Young's modulus of a rear end portion including an end surface on the rear end side can be smaller than the Young's modulus of the front end portion. In the configuration, in the gas sensor, the Young's modulus of a rear end portion including an end surface on the rear end side of the spacer 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 the gas sensor, the spacer is then in contact with the elastic body at an end surface on the rear end side in the axial direction.

[0016] Therefore, in the gas sensor, when an end surface (front end surface) on the front end side in the axial direction of the elastic body is inclined with respect to the axial direction, the inclination of the front end surface of the elastic body can be absorbed in the rear end portion of the spacer. That is, the gas sensor can absorb the inclination of the front end surface of the elastic body at the rear end portion of the spacer when the soft rear end portion of the spacer is bent in contact with the front end surface of the elastic body.

[0017] The spacer prevents "an inclination of the front end surface of the elastic body from being transmitted to the ceramic package via the spacer, and the ceramic package from being tilted from the axial direction by the rear end portion, which is softer and easier to bend than the front end portion." For example, in a case where the front end surface of the elastic body is tilted from the axial direction, a stress in a direction inclined from the axial direction may be transmitted from the front end surface of the elastic body to the ceramic package, and the ceramic package may be tilted from the axial direction due to such a stress. The spacer prevents such an occurrence by the rear end portion, which is softer and easier to bend than the front end portion.That is, the spacer prevents the occurrence of an event in which the ceramic housing is tilted due to stress in a direction inclined from the front end surface of the elastic body in the axial direction by absorbing the stress through the rear end portion. Furthermore, the front end portion of the spacer has sufficient hardness, which can remarkably prevent the ceramic housing from penetrating the spacer.

[0018] Therefore, the gas sensor achieves the effect that it can more effectively prevent the ceramic package from penetrating into a component (ie, the spacer) arranged on the rear end side of the ceramic package in a state where it is inclined with respect to the axial direction.

[0019] A gas sensor according to a third aspect is the gas sensor according to the first or second aspect, wherein a contact area between the spacer and the ceramic package is 3 mm 2 or more. In the configuration, the contact area between the spacer and the ceramic housing in the gas sensor is 3 mm 2 or more.

[0020] The inventors of the present invention believe that it is effective to sufficiently secure a contact area (hereinafter referred to as "contact area A1") between the spacer and the ceramic package to prevent the ceramic package from being fixed in a state where it is inclined relative to the axial direction. For example, it is considered that when the contact area A1 is small, the force is likely to act in a direction inclined relative to the axial direction from the spacer to the ceramic package, compared to a case where the contact area A1 is large, and as a result, the ceramic package is likely to be inclined relative to the axial direction.Furthermore, it is considered that when the contact area A1 is small, the contact between the spacer and the ceramic package is not stable compared to a case where the contact area A1 is large, and as a result, the ceramic package is likely to be tilted from the axial direction, for example, in a case where an impact is applied to the gas sensor. In view of the above, the inventors of the present invention verified an area of ​​the contact area A1 between the spacer and the ceramic package that is effective to prevent the ceramic package from being fixed in a state where it is 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. 2or more is possible to significantly prevent fixation of the ceramic package in a state inclined from the axial direction, compared with a case where the contact area A1 is set to less than 3 mm 2 is set.

[0021] In the gas sensor, the contact area (contact area A1) between the spacer and the ceramic housing is 3 mm 2 or more. Therefore, the gas sensor achieves the effect of being able to prevent fixation of the ceramic package in a state tilted from the axial direction, compared to a case where the contact area A1 between the spacer and the ceramic package is less than 3 mm 2 amounts.

[0022] The gas sensor is manufactured according to the following method, for example. First, a contact component is manufactured in which the ceramic package to which the terminal is attached, the spacer, and the elastic body are arranged in this order from the front end in the axial direction (pre-assembly). At a time of pre-assembly, a "compression spring fixing bracket" and a "swage ring" to be described later need not yet be mounted on an outer periphery of the ceramic package. After completion of pre-assembly, the sensor element is inserted with its rear end into the ceramic package (specifically, into an insertion hole provided on the front end of the ceramic package), to which the terminal is attached.The sensor element and the ceramic housing (contact component) are then joined together by pressing a kneading ring, which is intended to fix the ceramic housing, into which the sensor element is inserted from an outer circumference.

[0023] However, if the ceramic package is tilted from the axial direction at a time of pre-assembly, the ceramic package is integrated with the sensor element in the tilted state, that is, the state in which the ceramic package is tilted from the axial direction is fixed.

[0024] In view of the above, it is possible, for example, to prevent the ceramic package from being positioned in a state where it is inclined relative to the axial direction in the contact component described above by sufficiently securing the contact surface A1 between the spacer and the ceramic package at the time of pre-assembly. Specifically, by setting the contact surface A1 to 3 mm 2 or more at a time of pre-assembly, the gas sensor can prevent the occurrence of an event in which “the ceramic package is positioned in a state where it is inclined from the axial direction at a time of pre-assembly”.

[0025] A gas sensor according to a fourth aspect is the gas sensor according to any one of the first to third aspects, in which an area of ​​a portion in contact with the spacer in an end surface on the front end side of the elastic body can be 25% or more of a total area of ​​an end surface on the front end side of the elastic body. In the configuration, in the gas sensor, the area of ​​a portion in contact with the spacer in an end surface on the front end side of the elastic body is 25% or more of the total area of ​​an end surface on the front end side of the elastic body.

[0026] The inventors of the present invention have found it effective to sufficiently secure a contact area (hereinafter referred to as "contact area A2") between the spacer and the elastic body to prevent the ceramic package from being fixed in a state where it is inclined relative to the axial direction. For example, it is considered that when the contact area A2 is small, the force is likely to act in a direction inclined relative to the axial direction from the elastic body to the spacer, compared to a case where the contact area A2 is large, and as a result, the ceramic package in contact with the spacer is also likely to be inclined relative to the axial direction.When the contact area A2 is small, the contact between the elastic body and the spacer is unstable compared to a case where the contact area A2 is large, and it is considered that the spacer (especially an end surface of the spacer) is likely to be tilted from the axial direction, for example, in a case where an impact is applied to the gas sensor and the like. Since the spacer (especially an end surface of the spacer) is tilted from the axial direction, it is considered that the ceramic package in contact with the spacer (especially an end surface on the front end side of the spacer) will also be tilted from the axial direction.In view of this, the inventors of the present invention verified an area of ​​the contact area A2 between the spacer and the elastic body that effectively prevents the ceramic package from being fixed in a state where it is inclined from the axial direction. The inventors of the present invention confirmed that by setting the contact area A2 to 25% or more of a total area of ​​an end surface on the front end side of the elastic body, it is possible to significantly prevent fixation of the ceramic package in a state of inclination from the axial direction, compared with a case where the contact area A2 is set to less than 25%.

[0027] In the gas sensor, the area of ​​a portion in contact with the spacer in an end surface on the front end side of the elastic body, that is, the contact area A2 described above, is 25% or more of the total area of ​​an end surface on the front end side of the elastic body.

[0028] Therefore, the gas sensor achieves the effect of being able to remarkably prevent the ceramic package from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A2 is less than 25% of a total area of ​​an end surface on the front end side of the elastic body.

[0029] Here, for example, the gas sensor is manufactured using the following method. That is, the gas sensor is manufactured using a swaging process, in which the elastic body disposed at the opening end of the tubular body and the tubular body are swaged in a diameter-reducing manner to fix the elastic body to the opening end and seal the opening end with the elastic body. In this swaging process, there is a possibility that the elastic body is deformed, and the load acts on the spacer in a direction inclined to the axial direction.For example, in the swaging process, there is a possibility that a front end surface of the elastic body is pushed out in the axial direction toward the front end side in a state where it is inclined with respect to the axial direction, and exerts a load in a direction inclined with respect to the axial direction on the spacer. If the contact area A2 between the spacer and the elastic body is small at a time of the swaging process, the spacer will not be stabilized because the elastic body is soft, and the load will act on the spacer in a direction inclined with respect to the axial direction from the elastic body, and the spacer is likely to be inclined with respect to the axial direction.Since the spacer (especially a front end surface of the spacer) is inclined from the axial direction, there is a possibility that the ceramic package in contact with the spacer is also inclined from the axial direction.

[0030] In view of the above, for example, by sufficiently securing the contact area A2 between the spacer and the elastic body in the above-described swaging process, the gas sensor can prevent the ceramic housing from being tilted from the axial direction. Specifically, by setting the contact area A2 to 25% or more of a total area of ​​an end surface of the front end side of the elastic body in the swaging process, the gas sensor can prevent the occurrence of an event in which "the ceramic housing is tilted from the axial direction in the swaging process."

[0031] A gas sensor according to a fifth aspect is the gas sensor according to any one of the first to fourth aspects, in which a distance from a position of the center of gravity of a portion in contact with the ceramic case on an end surface on the front end side of the spacer, which is the center of gravity when the mass is practically uniformly distributed to a portion in contact with the ceramic case on an end surface on the front end side of the spacer, to a straight line obtained by extending an axis of the sensor element in the axial direction can be within 2 mm. In the configuration, in the gas sensor, a distance (hereinafter referred to as "distance L1") from a position of the center of gravity (hereinafter referred to as "center of gravity CG1") of a portion of the spacer in contact with the ceramic case to a straight line obtained by extending the axis in the axial direction is within 2 mm.

[0032] The inventors of the present invention considered that it is effective to bring the spacer and the ceramic package into contact with each other on a straight line obtained by extending the axis in the axial direction (ie, the axis extension line) to prevent the ceramic package from being fixed in a state where it is inclined from the axial direction. Specifically, the inventors of the present invention considered that if the distance L1 from the center of gravity CG1 of a contact surface between the spacer and the ceramic package to the axis extension line can be sufficiently reduced, the ceramic package can be effectively prevented from being fixed in a state where it is inclined from the axial direction.In view of the above, the inventors of the present invention examined the distance L1 between the center of gravity CG1 and the axis extension line, which effectively prevents the ceramic package from being fixed in a state where it is inclined from the axial direction. As a result, the inventors of the present invention confirmed that by setting the distance L1 between the center of gravity CG1 and the axis extension line to a value within 2 mm, the ceramic package can be remarkably prevented from being fixed in a state where it is inclined from the axial direction, compared with a case where the distance L1 is set to a value greater than 2 mm.

[0033] In the gas sensor, the distance (ie, the distance L1) from a position of the center of gravity (ie, the center of gravity CG1) of a portion of the spacer in contact with the ceramic case to the extension line of the axis is less than 2 mm.

[0034] Therefore, the gas sensor achieves the effect of being able to remarkably prevent the ceramic package from being fixed in a state where it is 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.

[0035] The gas sensor is manufactured, for example, using the pre-assembly process described above. However, if the ceramic housing is tilted from the axial direction at any time during pre-assembly, the ceramic housing is integrated with the sensor element in the tilted state, ie, the state in which the ceramic housing is tilted from the axial direction is fixed.

[0036] In view of the above, for example, by bringing the spacer and the ceramic package into contact with each other on the axis extension line at a time of pre-assembly, it is possible to prevent the ceramic package from being positioned in a state where it is inclined with respect to the axial direction in the contact member. Specifically, at a time of pre-assembly, the distance L1 from the center of gravity CG1 of a contact surface between the spacer and the ceramic package to the axis extension line is set to a value within 2 mm. This allows the gas sensor to prevent the occurrence of an event where "the ceramic package is positioned in a state where it is inclined with respect to the axial direction at a time of pre-assembly."

[0037] A gas sensor according to a sixth aspect is the gas sensor according to any one of the first to fifth aspects, in which a distance from a position of a center of gravity of a portion in contact with the spacer on an end surface on the front end side of the elastic body, which is a center of gravity when the mass is practically evenly distributed to a portion in contact with the spacer on an end surface on the front end side of the elastic body, to a straight line obtained by extending an axis of the sensor element in the axial direction can be within 2 mm. In the configuration, in the gas sensor, a distance (hereinafter referred to as "distance L2") from a position of the center of gravity (hereinafter referred to as "center of gravity CG2") of a portion of the elastic body in contact with the space to a straight line obtained by extending the axis in the axial direction is within 2 mm.

[0038] The inventors of the present invention considered that it is effective to bring the elastic body and the spacer into contact with each other on a straight line obtained by extending the axis in the axial direction (ie, the axis extension line) to prevent the ceramic package from being fixed in a state of inclination from the axial direction. Specifically, the inventors of the present invention considered that if the distance L2 from the center of gravity CG2 of a contact surface between the elastic body and the spacer to the axis extension line can be sufficiently reduced, the ceramic package can be effectively prevented from being fixed in a state of inclination from the axial direction.In view of the above, the inventors of the present invention examined the distance L2 between the center of gravity CG2 and the axis extension line, which effectively prevents the ceramic package from being fixed in a state where it is tilted from the axial direction. As a result, the inventors of the present invention confirmed that by setting the distance L2 from the center of gravity CG2 to the axis extension line to a value within 2 mm, the ceramic package can be prevented from being fixed in a state where it is tilted from the axial direction, compared to a case where the distance L2 is set to a value greater than 2 mm.

[0039] In the gas sensor, the distance (ie, the distance L2) from a position of the center of gravity (ie, the center of gravity CG2) of a portion of the elastic body in contact with the space to a straight line obtained by extending the axis in the axial direction is within 2 mm.

[0040] Therefore, the gas sensor achieves the effect of being able to remarkably prevent the ceramic package from being fixed in a state where it is 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.

[0041] For example, the gas sensor is manufactured using the swaging process described above. However, if the elastic body is deformed during the swaging process and the load acts in a direction inclined from the axial direction from the elastic body to the spacer, the ceramic package in contact with the spacer may also be inclined from the axial direction.

[0042] In view of the above, the gas sensor can prevent the ceramic package from being tilted from the axial direction, for example, by bringing the elastic body and the spacer into contact with each other on the axis extension line during the swaging process. Specifically, during the swaging process, the distance L2 from the center of gravity CG2 to the axis extension line is set to a value within 2 mm. This allows the gas sensor to prevent the occurrence of an event where "the ceramic package is positioned in a state where it is tilted from the axial direction during the swaging process."

[0043] A gas sensor according to a seventh aspect is the gas sensor according to any one of the first to sixth aspects, wherein a material of the elastic body is fluororubber. In this configuration, the material of the elastic body of the gas sensor is fluororubber, which has excellent performance in various aspects such as toughness and strength, and in particular, has excellent heat resistance and oil resistance. For this reason, the gas sensor achieves the effect of being able to maintain and improve the detection accuracy of the gas concentration by ensuring the sealability of the elastic body, for example, under a high-temperature environment.

[0044] A gas sensor according to an eighth aspect is the gas sensor according to any one of the first to seventh aspects, in which at least a portion of the spacer can be made of ceramic. In this configuration, at least a portion of the spacer in the gas sensor is constructed of ceramic, which has excellent heat resistance and generally has a higher melting point than resin. In the gas sensor, the spacer is arranged farther in the axial direction than the elastic body on the front end side. When at least a portion of the spacer is constructed of ceramic with excellent heat resistance, the gas sensor achieves the effect described below. That is, the gas sensor achieves the effect of being able to prevent the occurrence of an event in which at least a portion of the spacer is eroded by heat generated from a heat source on the front end side of the gas sensor.

[0045] According to the present invention, there can be provided a gas sensor which prevents a ceramic case from penetrating into a component disposed on a rear end side of the ceramic case in a state where it is inclined from an axial direction. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view schematically illustrating an example of a main configuration of a gas sensor according to an embodiment; Fig. 2 is an enlarged cross-sectional view of a main part showing the rear end side of the Fig. 1 illustrated in an enlarged form; Fig. 3 is a schematic cross-sectional view schematically illustrating an example of a main configuration of the gas sensor according to a first variation; Fig.4 is a schematic cross-sectional view schematically illustrating an example of a main configuration of the gas sensor according to a second variation; and Fig. Figure 5 is a graph showing a change in temperature and acceleration in a durability performance comparison test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] An embodiment (hereinafter also referred to as "the present embodiment") according to an aspect of the present invention will be described below with reference to the drawings. However, the embodiment described below is only an example of the present invention in all respects. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. That is, in carrying out the present invention, a specific configuration according to an embodiment can be suitably used.

[0047] The inventors of the present invention have found that the following problem occurs when the ceramic housing to which the contact piece is attached is fixed in a state inclined from the axial direction in the conventional gas sensor in which the elastic body is disposed on the rear end side in the axial direction of the sensor element of the ceramic housing. That is, in a case where the ceramic housing is fixed in a state inclined from the axial direction, an unintended stress (e.g., a stress in a direction not orthogonal to the axial direction) acts from the sensor element to the terminal piece attached to the ceramic housing.For this reason, the inventors of the present invention have found a problem that in a case where the ceramic package is fixed in a state where it is inclined with respect to the axial direction in the gas sensor, when an impact is applied to the gas sensor, the terminal fitting is more likely to break than in a case where the ceramic package is fixed parallel to the axial direction.

[0048] The present inventors further investigated and found that an event in which the ceramic package is fixed in a state where it is inclined relative to the axial direction occurs, for example, as described below. That is, the present inventors found that the above-described event occurs when the ceramic package penetrates an elastic body that is softer than the ceramic package in a state where it is inclined relative to the axial direction during a manufacturing stage of a gas sensor.

[0049] The conventional gas sensor is manufactured, for example, by the following pre-assembly process. First, a contact component is manufactured in which the ceramic housing, to which the terminal fitting is attached, and the elastic body are arranged in this order from an axially leading end side (pre-assembly step). Then, the sensor element is inserted into the contact component with its rear end side (specifically, into an insertion hole provided at the leading end side of the ceramic housing). Subsequently, the sensor element and the ceramic housing (contact component) are joined by swaging a kneading ring provided for fixing the ceramic housing, into which the sensor element is inserted from an outer periphery.

[0050] Note that in the present embodiment, an end surface on a front end side in the axial direction (axial direction of a sensor element) of each component is also referred to as a "front end surface." Similarly, an end surface on the rear end side in the axial direction of each component is also referred to as a "rear end surface."

[0051] In a conventional gas sensor manufactured by such a method, the ceramic package may penetrate an elastic body that is softer than the ceramic package, which is in a state of being inclined relative to the axial direction at the time of the pre-assembly process. In such a case, in a subsequent step of integrating the sensor element and the ceramic package, the state in which the ceramic package is inclined relative to the axial direction is fixed. That is, the ceramic package is integrated with the sensor element in the inclined state, and the state in which the ceramic package is inclined relative to the axial direction is fixed.

[0052] Furthermore, the conventional gas sensor is manufactured, for example, by the following swaging method in addition to the pre-assembly method described above. That is, the sensor element is manufactured by a swaging method in which a tubular body in which the sensor element and the contact member integrated with the sensor element are disposed, and the elastic body disposed at an opening end of the tubular body are swaged in a diameter-reducing manner. In the swaging method, the elastic body is fixed to the opening end of the tubular body, and the opening end of the tubular body is sealed by the elastic body.

[0053] In this swaging process, the soft elastic body can be deformed to seal the opening end of the tubular body, and the elastic body (specifically, an end surface on the front end side in the axial direction) can exert a load on the ceramic shell in a direction inclined to the axial direction. For example, in the swaging process, a front end surface of the elastic body is pushed out to the front end side in the axial direction in a state where it is inclined to the axial direction, and a load can be exerted on the ceramic shell in a direction inclined to the axial direction.

[0054] The inventors of the present invention have confirmed that, for example, in a manufacturing stage of a gas sensor or the like (particularly, the pre-assembly process, the swaging process, and the like described above), the ceramic package can penetrate into the elastic body in a state of being inclined with respect to the axial direction, and the state can be fixed.

[0055] In view of the above, the inventors of the present invention considered the use of a spacer to prevent "a ceramic housing from penetrating an elastic body that is softer than the ceramic housing in a state where it is inclined from an axial direction." That is, the inventors of the present invention considered that by disposing a spacer between a ceramic housing to which a terminal fitting is attached and a soft elastic body that seals an opening end of a tubular body, the ceramic housing can be prevented from penetrating the elastic body in a state where it is inclined from an axial direction.Furthermore, the inventors of the present invention have found that it is effective to sufficiently harden a portion on the front end side in the axial direction of the spacer to prevent the ceramic package from penetrating into the spacer arranged on the rear end side of the ceramic package.

[0056] In order to prevent the ceramic package from penetrating the spacer (particularly, a front end portion of the spacer), the present inventors experimentally determined the hardness (softness) to be given to the front end portion of the spacer (for details of the experiment, see [Example] described later). As a result, the present inventors confirmed that by setting the Young's modulus of the front end portion of the spacer to 80 GPa or more, it is possible to significantly prevent the ceramic package from penetrating the spacer (particularly, a front end portion of the spacer) compared to a case where the Young's modulus is set to less than 80 GPa.

[0057] In view of the above, a gas sensor according to an aspect of the present invention includes a spacer between a ceramic housing to which a terminal fitting is attached and a soft elastic body that seals an opening end of a tubular body. In the gas sensor according to an aspect of the present invention, the ceramic housing is then in contact with the spacer arranged on the rear end side of the ceramic housing, specifically with an end surface (front end surface) on the front end side of the spacer. In the gas sensor according to an aspect of the present invention, the Young's modulus of a front end portion including the front end surface of the spacer is 80 GPa or more, that is,the front end portion of the spacer has sufficient hardness that can significantly prevent penetration of the ceramic package into the spacer (especially a front end portion of the spacer).

[0058] For this reason, in the gas sensor according to one aspect of the present invention, an event such as "the ceramic case penetrates into the spacer disposed on the rear end side of the ceramic case in a state where it is inclined with respect to the axial direction, and such a state is fixed" does not occur. Therefore, the gas sensor according to one aspect of the present invention achieves the effect of being able to prevent the ceramic case from penetrating a component (ie, the spacer) disposed on the rear end side of the ceramic case in a state where it is inclined with respect to the axial direction.The gas sensor according to one aspect of the present invention prevents the ceramic housing from penetrating a component disposed on the rear end side of the ceramic housing in a state where it is inclined relative to the axial direction, thereby reducing the possibility of the terminal breaking when an impact is applied to the gas sensor. First, a gas sensor 1 as a gas sensor according to one aspect of the present invention will be described below with reference to FIG. Fig. 1 and Fig. 2 described. [Configuration example]<Gesamtumriss des Gassensors>

[0059] Fig. Fig. 1 is a schematic cross-sectional view schematically illustrating an example of a main configuration of the gas sensor 1 according to the present embodiment. That is, Fig.Figure 1 schematically shows a configuration of a cross section of the gas sensor 1 parallel to and in contact with an axis in a longitudinal direction (axis line, line along a left-right direction in the diagram). The gas sensor 1 is an example of a "gas sensor" of the present invention and is a gas sensor capable of detecting the concentration (specific gas concentration) of a specific gas such as oxygen or NO. x in a measured gas such as the exhaust of a motor vehicle. As in Fig. As shown in Figure 1, the gas sensor 1 has an axis and is configured to extend along the longitudinal direction (axial direction) and to have a front end and a rear end as ends in the longitudinal direction. One end in the longitudinal direction is a front end, and another end is a rear end. In the example of Fig.1, the gas sensor 1 is arranged such that a front end of the gas sensor 1 points in a left direction and a rear end of the gas sensor 1 points in a right direction. That is, the left-right direction in Fig.1 corresponds to the longitudinal direction (axial direction). In the present embodiment, the gas sensor 1 includes a sensor element 10, a tubular body 20 (a main terminal 21, an outer tube 22, and a fixing bolt 23), a terminal 30, a lead wire 40, an elastic body 50, a ceramic case 60, a spacer 70, and a protective cover 80. In the gas sensor 1, the sensor element 10 is surrounded by the tubular body 20 and the protective cover 80, and the tubular body 20 and the protective cover 80 together form a casing member (shell) that houses the sensor element 10 inside. The sensor element 10 is arranged coaxially with the tubular body 20 and the protective cover 80, and an extension direction of a central axis of the sensor element 10 coincides with an axial direction of the gas sensor 1. (sensor element)

[0060] The sensor element 10 is an example of a “sensor element” of the present invention and is configured to extend along the axial direction (left-right direction in Fig. 1). The Fig. The sensor element 10 shown in Figure 1 is an elongated, flat, plate-shaped element. The sensor element 10 includes a detection unit 11 at the front end and a connector electrode (connector electrode 12) at the rear end. The connector electrode 12 of the sensor element 10 is in Fig. 2. The front end of the Fig. 1 is coated with an outer porous layer, and the outer porous layer serves as a protective layer that prevents the occurrence of a crack in an element body of the sensor element 10, for example, due to the adhesion of moisture or the like in the measured gas.

[0061] In the gas sensor 1, the sensor element 10 is arranged so that the front end side faces the front end of the gas sensor 1. In one aspect of the sensor element 10, for example, measurement gas introduced into the sensor element 10 is reduced or decomposed in the sensor element 10, and an oxygen ion is generated. In the gas sensor 1 including the sensor element 10, the concentration of the specific gas, which is the target gas for detection, in the measurement gas is determined based on the fact that the amount of oxygen ions flowing in the sensor element 10 is proportional to the concentration of the specific gas.

[0062] In the Fig.1, the front end side of the sensor element 10 is surrounded by the protective cover 80, the rear end side projects into the outer tube 22, and a substantially central portion between the front end side and the rear end side is fixed within the main connector 21 by an annular component 90 so that a space between the two end portions is hermetically sealed. (Annular component)

[0063] In the Fig.In the example shown in Figure 1, the annular component 90 includes a first ceramic substrate 91, a green compact 92, and a second ceramic substrate 93. The first ceramic substrate 91 and the second ceramic substrate 93 are ceramic insulators. Specifically, a through-hole (not shown) having a shape corresponding to the cross-sectional shape of the sensor element 10 is provided at an axial center position of the first ceramic substrate 91 and the second ceramic substrate 93, and the sensor element 10 is inserted into the through-hole, so that the first ceramic substrate 91 and the second ceramic substrate 93 are annularly mounted on the sensor element 10. Note that the first ceramic substrate 91 is fixed to a tapered surface of the main terminal 21 on the left side in the diagram.

[0064] The green compact 92, on the other hand, is manufactured by molding ceramic powder such as talc. Similar to the first ceramic substrate 91 and the second ceramic substrate 93, the green compact 92 is obtained when the sensor element 10 is inserted into a through-hole, so that two molded bodies (not shown) annularly mounted on the sensor element 10 are arranged inside the main terminal 21 in a state of being annularly mounted around the sensor element 10, and then further compressed and integrated. Specifically, the ceramic particles constituting the green compact 92 are surrounded by the first ceramic substrate 91, the second ceramic substrate 93, and the main terminal 21, and are densely arranged in a space through which the sensor element 10 penetrates into the interior of the main terminal 21.By the compressed filling with the green compact 92, an airtight seal is achieved between the front end side and the rear end side of the sensor element 10.

[0065] Fig. 1 shows an example in which the annular component 90 includes the first ceramic carrier 91, the green compact 92, and the second ceramic carrier 93. However, in the gas sensor 1, it is not absolutely necessary for the annular component 90 to be constructed from the first ceramic carrier 91, the green compact 92, and the second ceramic carrier 93. Fig. The gas sensor 1 shown in Fig. 1 includes the annular component 90 which fixes the sensor element 10 inside the main terminal 21 and hermetically seals a space between the front end side and the rear end side of the sensor element 10. (Tubular body)

[0066] The tubular body 20 is an example of a "tubular body" of the present invention. The tubular body 20 is, for example, a tubular (e.g., cylindrical) component made of metal and has an opening end. The sensor element 10 is arranged inside the tubular body 20. In the Fig. 1, the tubular body 20 includes the tubular main fitting 21, the tubular outer tube 22 and the fastening bolt 23, each of which is a metal component.

[0067] The main connector 21 is a tubular (e.g., cylindrical) metal component. Inside the main connector 21, the sensor element 10 and the annular component 90 for fastening are housed, mounted annularly on the sensor element 10. This means that the main connector 21 is further mounted annularly on the annular component 90, which is mounted annularly around the sensor element 10. Fig. The main connector 21 shown in Fig. 1 is configured to surround the sensor element 10 along the axial direction (longitudinal direction), and in particular, is configured to surround an area excluding a part of the front end side and the rear end side of the sensor element 10.

[0068] The outer tube 22 is a cylindrical (e.g. cylindrical) component made of metal, and the Fig. 1 covers the rear end of the sensor element 10, the ceramic housing 60 (connector 30) and a periphery of the spacer 70.

[0069] An end portion (opening end) on the front end side of the outer tube 22 is welded and fixed to an outer peripheral end portion on the rear end side of the main fitting 21. Further, the elastic body 50 is arranged at an opening end on the rear end side of the outer tube 22 to seal the opening end. On the rear end side of the outer tube 22, a reduced diameter portion 221 is formed for swaging a part of the elastic body 50 to seal an opening end on the rear end side from a circumference. In the reduced diameter portion 221, the outer tube 22 is swaged from the outside in a diameter-reducing manner over the entire circumferential direction of the outer tube 22, so that a reaction force directed toward the outside in the radial direction is generated in the elastic body 50, thereby sealing the outer tube 22.

[0070] Furthermore, the lead wire 40 is drawn out from an opening end at the rear end side of the outer tube 22, which is sealed by the elastic body 50, through a through hole (not shown) formed inside the elastic body 50. Outside air (atmosphere) is introduced into an interior space of the outer tube 22 between the coating of the lead wire 40 and a metal wire (conductor) (in other words, the inside of the coating), and the interior space of the outer tube 22 has a reference gas atmosphere (air). A rear end of the sensor element 10 is arranged in the interior space of the outer tube 22 filled with reference gas.

[0071] The fixing bolt 23 is a ring-shaped member used to fix the gas sensor 1 at a measurement position (fixing position) and is fixed coaxially with the main connector 21. The fixing bolt 23 includes a threaded bolt portion and a holding portion that is held when the bolt portion is screwed in. The bolt portion of the fixing bolt 23 is screwed with a nut provided at a fixing position of the gas sensor 1. For example, when the bolt portion of the fixing bolt 23 is screwed into a nut (nut portion) provided in an exhaust pipe of an automobile, the gas sensor 1 is fixed to the exhaust pipe in a mode where the side of the protective cover 80 is exposed to the inside of the exhaust pipe.

[0072] As described above, the Fig.1 comprises the main connecting piece 21, the outer tube 22 and the fastening bolt 23 and is configured as a tubular (e.g., cylindrical) component as a whole, in particular as a tubular component extending in the axial direction. That is, the Fig.The tubular body 20 shown in Fig. 1 is an axially extending cylindrical member including the tubular main fitting 21, the tubular outer tube 22 welded and fixed at an outer peripheral end portion on the rear end side of the main fitting 21, and the fixing bolt 23 arranged on an outer periphery on the front end side of the main fitting 21. For example, the tubular body 20 and the gas sensor 1 (sensor element 10) are coaxial, and the tubular body 20 has a front end and a rear end as ends in the axial direction (longitudinal direction) and is arranged so that the front end of the tubular body 20 is opposite to the front end of the gas sensor 1.Then, inside the tubular body 20, the sensor element 10, the annular component 90 for fixing annularly mounted on the sensor element 10, the ceramic housing 60 (connector 30), and the spacer 70, and an opening end on the rear end side are sealed by the elastic body 50. The reduced diameter portion 221 for fixing the elastic body 50 for sealing an opening end of the tubular body 20 is formed on the rear end side of the tubular body 20 (outer tube 22), and the reduced diameter portion 221 deforms a part of the elastic body 50 from a circumference.

[0073] It should be noted that in the gas sensor 1, the tubular body 20 does not necessarily require the main connector 21, the outer tube 22, and the fixing bolt 23. The tubular body 20 may not include the fixing bolt 23, or the main connector 21 and the outer tube 22 may be integrally formed. In the gas sensor 1, the tubular body 20 only needs to be a tubular component in which the sensor element 10 is arranged and an opening end is formed. (connector)

[0074] The terminal 30 is an example of a "terminal" of the present invention. The terminal 30 is a metal component (contact component) extending in the axial direction. In the gas sensor 1, the sensor element 10 (specifically, the connector electrode 12 of the sensor element 10) and the lead wire 40 are electrically connected via the terminal 30. Although in Fig.2, the terminal fitting 30 includes an element contact portion 31 electrically connected to the connector electrode 12 of the sensor element 10 on the front end side, and a lead wire holding portion 32 crimping and holding the lead wire 40 on the rear end side. (ceramic housing)

[0075] The ceramic package 60 is an example of a “ceramic package” of the present invention. The ceramic package 60 is a ceramic component that covers the rear end side of the sensor element 10 (specifically, the connector electrode 12 provided on the rear end side of the sensor element 10) and the front end side of the terminal piece 30 (specifically, the terminal piece 30 described with reference to Fig. 2 described element contact section 31). That is, in the Fig.In the gas sensor 1 shown in Figure 1, the sensor element 10 (in particular the connector electrode 12) and the terminal piece 30 (in particular the element contact portion 31) are electrically connected in the ceramic housing 60.

[0076] For example, the rear end of the sensor element 10 provided with the connector electrode 12 is inserted into the ceramic housing 60, which accommodates the front end (element contact portion 31) of the terminal 30. In this insertion state, the connector electrode 12 provided on the rear end of the sensor element 10 and the front end (element contact portion 31) of the terminal 30 are in contact with each other. The front end (element contact portion 31) of the terminal 30 can be sandwiched and fixed between the rear end of the sensor element 10 provided with the connector electrode 12 and the ceramic housing 60, so that the connector electrode 12 of the sensor element 10 and the terminal 30 are electrically connected.

[0077] In the gas sensor 1, there is a gap between the ceramic housing 60 and the tubular body 20 (outer tube 22), that is, the ceramic housing 60 is not in contact with the tubular body 20. A position of the ceramic housing 60 within the tubular body 20 can be fixed without being in contact with the tubular body 20 by integrating it into the sensor element 10. As shown in Fig. 1, a position of the sensor element 10 within the tubular body 20 is fixed by the annular component 90 and the tubular body 20 (specifically, the main fitting 21 and the outer tube 22). A position of the ceramic housing 60 inside the tubular body 20 can be fixed without contact with the tubular body 20 by integrating it into the sensor element 10, whose position inside the tubular body 20 is fixed by the annular component 90 and the tubular body 20.

[0078] The ceramic housing 60 (more specifically, a contact member in which the ceramic housing 60, the spacer 70, and the elastic body 50 are arranged in this order from the front end side in the axial direction) can be integrated with the sensor element 10 as described below. That is, after the lead wire holding portion 32 of the terminal fitting 30 is connected to a front end of the lead wire 40 inserted through the elastic body 50 and the spacer 70, the ceramic housing 60, which is provided with an insertion opening on the front end side in the axial direction, is assembled with the terminal fitting 30. More specifically, the ceramic housing 60, in which a fixing fitting provided with a compression spring 61 (see Fig. 2) and a kneading ring or die-formed ring 62 (see Fig.2) is not yet assembled, is mounted on the terminal 30, in which a front end of the lead wire 40 is connected to the lead wire holding portion 32. Thereafter, a fixing fitting including the compression spring 61 and the kneading ring 62 is mounted on an outer periphery of the ceramic housing 60 to produce a contact member (pre-assembly). The compression spring 61 is, for example, a leaf spring member having a trapezoidal shape in a cross-sectional view without an upper base portion, and generates an elastic force as a restoring force when an external force acts on a free end portion of the compression spring 61. When the sensor element 10 and the contact member described above are integrated, the kneading ring 62 is welded in a state in which the sensor element 10 (specifically, a rear end portion of the sensor element 10) is inserted into an insertion opening of the ceramic housing 60, that is,The kneading ring 62 is deformed to be reduced in size by an external force. This narrows a space of the insertion opening of the ceramic package 60, and the sensor element 10 and the ceramic package 60 (contact member) are integrated. At this time, the element contact portion 31 of the terminal 30 comes into contact with the connector electrode 12 of the sensor element 10. For this reason, in the gas sensor 1, electrical conduction between the sensor element 10 and the outside is established via the lead wire 40 connected to the terminal 30 and a contact member (terminal 30) connected to the lead wire 40. (conductor wire)

[0079] The lead wire 40 is electrically connected to the connector electrode 12 of the sensor element 10 via the terminal piece 30 and extends outwardly from an opening end of the tubular body 20. In particular, the lead wire 40 is electrically connected to the rear end side (specifically, the lead wire holding portion 32 described with reference to Fig. 2) of the terminal fitting 30 is connected to the front end side of the lead wire 40, and the rear end side of the lead wire 40 extends outward from an opening end of the tubular body 20. Then, as described above, a gap between the lead wire 40 and the tubular body 20 (outer tube 22) is sealed by the elastic body 50.

[0080] For example, the lead wire 40 is inserted into a through-hole (not shown) provided throughout the elastic body 50 and the spacer 70. An end portion on the front end side of the lead wire 40 is crimped and fixed to the rear end side (lead wire holding portion 32) of the terminal fitting 30, and an end portion on the rear end side of the lead wire 40 is connected to an external device (controller), a power supply, or the like. Thus, the sensor element 10 (specifically, the connector electrode 12 of the sensor element 10) is electrically connected to an external device, a power supply, and the like via the terminal fitting 30 and the lead wire 40. Although Fig.While Figure 1 shows an example in which two connectors 30 and two lead wires 40 are present, this is for simplicity of illustration only. In practice, the gas sensor 1 contains as many connectors 30 and lead wires 40 as are required for the electrical connection described above. (Elastic body)

[0081] The elastic body 50 is an example of an “elastic body” of the present invention. The elastic body 50 is a member having elasticity and is made of, for example, rubber. The elastic body 50 is arranged to have an opening end (in the Fig.1, seals an opening end (at the rear end side) of the tubular body 20, and the lead wire 40 is inserted into the elastic body 50. Specifically, an axially extending through-hole is formed in the inside of the elastic body 50, and for example, a plurality of axially extending through-holes are formed. The lead wire 40 is accommodated (inserted) in a through-hole formed inside the elastic body 50, and for example, each of a plurality of lead wires 40 is accommodated (inserted) in each of a plurality of through-holes formed inside the elastic body 50.

[0082] A material of the elastic body 50 is, for example, fluororubber. Fluororubber has excellent properties in various aspects such as toughness and strength, and is particularly excellent in heat resistance and oil resistance. For this reason, the gas sensor 1 uses the elastic body 50 made of fluororubber so that, for example, the sealing properties of the elastic body 50 can be ensured in a high-temperature environment and the effect of maintaining and improving the detection accuracy of the gas concentration can be achieved. However, it is not essential that the gas sensor 1 use fluororubber as the material of the elastic body 50, and a material with elasticity can be used as the material of the elastic body 50 in the gas sensor 1. (spacer)

[0083] The spacer 70 is an example of a "spacer" of the present invention. The spacer 70 is arranged between the ceramic case 60 and the elastic body 50 in the axial direction of the gas sensor 1 (sensor element 10), further to the rear end side than the ceramic case 60 and further to the front end side of the elastic body 50. The spacer 70 is in contact with the ceramic case 60 at a front end surface of the spacer 70 (specifically, a rear end surface of the ceramic case 60) and with the elastic body 50 at a rear end surface of the spacer 70 (specifically, a front end surface of the elastic body 50). For example, a position of the spacer 70 within the tubular body 20 (outer tube 22) is fixed by the ceramic case 60 and the elastic body 50.That is, the spacer 70 is disposed (embedded) between the ceramic case 60 and the elastic body 50 inside the tubular body 20. That is, a front end surface of the spacer 70 is in contact with a rear end surface of the ceramic case 60, and as described above, the ceramic case 60 is integrated with the sensor element 10 so that the position within the tubular body 20 is fixed. Furthermore, a rear end surface of the spacer 70 is in contact with a front end surface of the elastic body 50, and as described above, the elastic body 50 is provided at an opening end (in the position shown in FIG. Fig.1, an opening end (at the rear end side) of the tubular body 20 is fixed by the reduced-diameter portion 221. For this reason, a position of the spacer 70 within the tubular body 20 (outer tube 22) is fixed by the ceramic housing 60 and the elastic body 50.

[0084] The lead wire 40 is inserted into the Fig. 1 spacers 70 are inserted. For example, in the Fig. 1, the lead wire 40 and the terminal 30 (specifically, a rear end of the terminal 30 electrically connected to the lead wire 40) are housed within the spacer 70.

[0085] The spacer 70 is made of, for example, a heat-resistant material. When the spacer 70 is constructed of a heat-resistant material, the spacer 70, which is located further toward the front end side in the axial direction than the elastic body 50, can be prevented from being eroded by heat generated from a heat source at the front end side of the gas sensor 1. For example, by interposing the spacer 70 between the elastic body 50 and the ceramic case 60, it is possible to prevent an excessive temperature rise of the elastic body 50 at the time of use of the gas sensor 1 or the like. That is, the thermal conductivity of the spacer 70 is desirably low from the viewpoint of preventing heat transfer to the elastic body 50.However, while the temperature rise of the elastic body 50 is reduced by the spacer 70, the temperature of the spacer 70 becomes high, and the spacer 70 itself must have sufficient heat resistance. In view of the above, by constructing the spacer 70 from a heat-resistant material, it is possible to prevent the occurrence of an event in which the spacer 70 itself is eroded by the heat generated from a heat source, while simultaneously preventing heat transfer from the heat source to the elastic body 50.

[0086] In the gas sensor 1, the spacer 70 is made of ceramic. Ceramic has excellent heat resistance and generally has a higher melting point than resin. In the gas sensor 1, the spacer 70 is then arranged further forward in the axial direction than the elastic body 50. When the spacer 70 is made of ceramic with excellent heat resistance, the gas sensor 1 achieves the effect described below. That is, the gas sensor 1 achieves the effect of being able to prevent the occurrence of an event in which the spacer 70 is abraded by heat generated from a heat source on the front end side of the gas sensor 1. However, it is not essential for the gas sensor 1 that the spacer 70 be made of ceramic, and a material with heat resistance can be used as the material of the spacer 70 in the gas sensor 1.

[0087] In the spacer 70, at least the Young's modulus of a front end portion including a front end surface is 80 GPa or more. In the gas sensor 1, the Young's modulus of the entire spacer 70 is 80 GPa or more, that is, the Young's modulus of not only a front end portion but also the entire spacer 70 is 80 GPa or more.

[0088] In the gas sensor 1, the spacer 70 is arranged between the ceramic housing 60 and the elastic body 50. In the gas sensor 1, it is not the ceramic housing 60 (specifically, a rear end surface of the ceramic housing 60) that contacts the elastic body 50, but the spacer 70 arranged on the rear end side of the ceramic housing 60, specifically, a front end surface of the spacer 70, that contacts the elastic body 50. For this reason, the gas sensor 1 can prevent the ceramic housing 60 from penetrating the elastic body 50 in a state tilted from the axial direction.

[0089] Specifically, in the gas sensor 1, the ceramic case 60 is in contact with the spacer 70 disposed on the rear end side of the ceramic case 60, particularly with a front end surface of the spacer 70. Then, the Young's modulus of a front end portion including a front end surface of the spacer 70 is 80 GPa or more, that is, a front end portion of the spacer 70 has sufficient hardness, which can substantially prevent the ceramic case 60 from penetrating into the spacer 70 (particularly the front end portion of the spacer 70).

[0090] For this reason, in the gas sensor 1, an event such as "the ceramic case 60 penetrates the spacer 70 arranged on the rear end side of the ceramic case 60 in a state where it is inclined with respect to the axial direction, and such a state is fixed" does not occur. Therefore, the gas sensor 1 achieves the effect of being able to prevent the ceramic case 60 from penetrating a component (ie, the spacer 70) arranged on the rear end side of the ceramic case 60 in a state where it is inclined with respect to the axial direction. The gas sensor 1 prevents "the ceramic case 60 from penetrating a component arranged on the rear end side of the ceramic case 60 in a state where it is inclined with respect to the axial direction," thus reducing the possibility of the terminal fitting 30 breaking when an impact is applied to the gas sensor 1. (protective cover)

[0091] The protective cover 80 is a substantially cylindrical outer member that protects a predetermined area on the front end side, ie, a portion of the sensor element 10 that comes into direct contact with the measured gas at the time of use. Fig.The protective cover 80 shown in FIG. 1 is configured to surround at least a portion of the front end side of the tubular body 20 (main fitting 21) along the axial direction (longitudinal direction) and extend beyond a front end of the sensor element 10. For example, the protective cover 80 is configured to surround a portion of the front end side of the tubular body 20 and the sensor element 10 around the axis. The protective cover 80 has a front end and a rear end as ends in the axial direction, and the front end of the protective cover 80 is located further toward the front end side of the gas sensor 1 than the front end of the sensor element 10.

[0092] The protective cover 80 is provided with a plurality of through-holes (not shown) through which gas can flow. Measured gas flowing into the protective cover 80 through the through-hole is a direct detection target in the sensor element 10. Note that the type, number, arrangement position, shape, and the like of the through-holes provided in the protective cover 80 can be appropriately determined, taking into account the manner in which the measured gas flows into the protective cover 80.

[0093] In the Fig.1, the protective cover 80 includes a bottomed tubular inner cover 81 covering a front end of the sensor element 10, and a bottomed tubular outer cover 82 covering the inner cover 81. The inner cover 81 includes a first member 81B and a second member 81A, and is configured to cover a periphery of at least a part of the front end side of the sensor element 10 and the tubular body 20 (main fitting 21). The first member 81B extends along the axial direction from an outer wall of a front end portion of the tubular body 20 and is configured to further extend along the axial direction after a diameter in a direction perpendicular to the axial direction decreases by a portion beyond a front end of the tubular body 20.The second member 81A is configured to cover a periphery of a part of the front end side of the first member 81B. The outer cover 82 is configured to cover a periphery of the inner cover 81.

[0094] A sensor element chamber is formed as a space surrounded by the inner cover 81, and a front end of the sensor element 10 is arranged in the sensor element chamber. An opening is appropriately provided in the first member 81B and the second member 81A of the inner cover 81 and the outer cover 82, so that the sensor element chamber communicates with a space outside the protective cover 80. However, the configuration and shape of the protective cover 80 are not limited to such an example. A configuration and shape of the protective cover 80 can be appropriately determined according to an embodiment.

[0095] For example, a metal material such as stainless steel (e.g., SUS) can be used as the material for the protective cover 80. The protective cover 80 can be manufactured by appropriately molding a metal material. Note that the protective cover 80 can be omitted in one configuration of the gas sensor 1. <Einzelheiten der hinteren Endseite des Gassensors>

[0096] Fig. Fig. 2 is an enlarged cross-sectional view schematically showing a main part of the gas sensor 1, particularly a cross-sectional view showing the rear end side of the gas sensor in an enlarged manner. Fig. 2, the left-right direction in the diagram is the axial direction (longitudinal direction) of the gas sensor 1 (sensor element 10), and the left side in the diagram is the front end side, and the right side in the diagram is the rear end side.

[0097] As in Fig.2, the ceramic case 60, the spacer 70, and the elastic body 50 are arranged in this order from the front end side to the rear end side on the rear end side of the gas sensor 1. A rear end surface of the ceramic case 60 is in contact with a front end surface of the spacer 70, and a rear end surface of the spacer 70 is in contact with a front end surface of the elastic body 50. As described above, in the gas sensor 1, the Young's modulus of the entire spacer 70 is 80 GPa or more. For this reason, in the gas sensor 1, the Young's modulus of a front end portion of the spacer 70 is 80 GPa or more, that is, the ceramic case 60 (particularly, a rear end surface of the ceramic case 60) is in contact with the spacer 70 (particularly, a front end surface of the spacer 70) with a Young's modulus of 80 GPa or more.

[0098] The Fig. 1 and Fig. For example, the gas sensor 1 shown in Figure 2 is manufactured by the following method. That is, first, a contact component is manufactured in which the ceramic housing 60, to which the terminal 30 is attached, the spacer 70, and the elastic body 50 are arranged in this order from the front end side in the axial direction (pre-assembly). At the time of pre-assembly, a fixing fitting that has the Fig.2 and the kneading ring 62 have not yet been mounted on an outer periphery of the ceramic package 60. As described above, the compression spring 61 is, for example, a leaf spring component, and the kneading ring 62 is deformed and reduced in size by external force to integrate the sensor element 10 and the ceramic package 60 (contact component). After completion of the pre-assembly, the sensor element 10 is inserted with its rear end side into the ceramic package 60 (specifically, into an insertion hole provided on the front end side of the ceramic package 60), to which the terminal fitting 30 is attached. Subsequently, the sensor element 10 and the ceramic package 60 (contact component) are joined by swaging the kneading ring 62, which is provided for fixing the ceramic package 60, into which the sensor element 10 is inserted from an outer periphery.

[0099] The gas sensor 1 is manufactured, for example, by the following method in addition to the pre-assembly method described above. That is, the gas sensor 1 is manufactured by a swaging method in which the elastic body 50 disposed at an opening end of the tubular body 20 (outer tube 22) and the tubular body 20 is swaged in a diameter-reducing manner to fix the elastic body 50 to an opening end of the tubular body 20 and seal the opening end with the elastic body 50. (Regarding the type of contact between ceramic housing and spacer)

[0100] As in Fig.2, in the gas sensor 1, the contact area A1 between the spacer 70 (specifically, a front end surface of the spacer 70) and the ceramic housing 60 (specifically, a rear end surface of the ceramic housing 60) is set to be sufficiently large. In the gas sensor 1, the contact area A1 is 3 mm 2 or more. However, in gas sensor 1, it is not absolutely necessary to set the contact area A1 to 3 mm 2 or more, and the contact area A1 can also be less than 3 mm 2 be.

[0101] The inventors of the present invention believe that it is effective to sufficiently secure the contact area A1 between the spacer 70 and the ceramic package 60 to prevent the ceramic package 60 from being fixed in a state where it is inclined relative to the axial direction. For example, it is considered that when the contact area A1 is small, the force is likely to act in a direction inclined relative to the axial direction from the spacer 70 to the ceramic package 60, compared to a case where the contact area A1 is large, and as a result, the ceramic package 60 is likely to be inclined relative to the axial direction.Furthermore, it is considered that when the contact area A1 is small, the contact between the spacer 70 and the ceramic package 60 is not stable compared to a case where the contact area A1 is large, and as a result, the ceramic package 60 is likely to be tilted from the axial direction, for example, in a case where an impact is applied to the gas sensor 1. In view of the above, the inventors of the present invention verified an area of ​​the contact area A1 between the spacer 70 and the ceramic package 60, which is effective to prevent the ceramic package 60 from being fixed in a state where it is 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. 2or more, it is possible to significantly prevent the ceramic housing 60 from being fixed in a state inclined from the axial direction, compared with a case where the contact area A1 is set to less than 3 mm 2 is set.

[0102] In the gas sensor 1, the contact area A1 between the spacer 70 and the ceramic housing 60 is 3 mm 2 or more. Therefore, the gas sensor 1 achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is tilted from the axial direction, compared with a case where the contact area A1 between the spacer 70 and the ceramic package 60 is less than 3 mm 2 amounts.

[0103] Here, the gas sensor 1 is manufactured, for example, by the pre-assembly method as described above. Then, when the ceramic housing 60 is tilted from the axial direction at a time of pre-assembly, the ceramic housing 60 is integrated with the sensor element 10 in the tilted state, that is, the state in which the ceramic housing 60 is tilted from the axial direction is fixed.

[0104] In view of the above, it is possible, for example, to prevent the ceramic housing 60 from being positioned in a state where it is inclined relative to the axial direction in the contact component described above by sufficiently securing the contact area A1 between the spacer 70 and the ceramic housing 60 at the time of pre-assembly. Specifically, by setting the contact area A1 to 3 mm 2or more at a time of pre-assembly, the gas sensor 1 can prevent the occurrence of an event in which “the ceramic case 60 is positioned in a state where it is inclined from the axial direction at a time of pre-assembly”.

[0105] As in Fig.2, in the gas sensor 1, the spacer 70 and the ceramic case 60 are in contact with each other on a straight line obtained by axially extending the axis of the sensor element 10 (gas sensor 1) (i.e., an extension line of the axis). For example, in the gas sensor 1, the distance L1 from a position of the center of gravity CG1 of a "portion of the spacer 70 (specifically, a front end surface of the spacer 70) in contact with the ceramic case 60 (specifically, a rear end surface of the ceramic case 60)" 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 the mass is practically uniformly distributed in a portion in contact with the ceramic case 60 (specifically, a rear end surface of the ceramic case 60) on a front end surface of the spacer 70.It should be noted that for gas sensor 1, the distance L1 does not necessarily have to be within 2 mm and the distance can also be greater than 2 mm.

[0106] The inventors of the present invention considered it appropriate to bring the spacer 70 and the ceramic housing 60 into contact with each other on the axis extension line of the sensor element 10 (gas sensor 1) in order to prevent the ceramic housing 60 from being fixed in a state inclined from the axial direction. Specifically, the inventors of the present invention considered that if the distance L1 from the center of gravity CG1 of a contact surface between the spacer 70 and the ceramic housing 60 to the axis extension line can be sufficiently reduced, the ceramic housing 60 can be effectively prevented from being fixed in a state inclined from the axial direction.In view of the above, the inventors of the present invention examined the distance L1 between the center of gravity CG1 and the axis extension line, which effectively prevents the ceramic package 60 from being fixed in a state where it is inclined from the axial direction. As a result, the inventors of the present invention confirmed that by setting the distance L1 from the center of gravity CG1 to the axis extension line to a value within 2 mm, the ceramic package 60 can be remarkably prevented from being fixed in a state where it is inclined from the axial direction, compared with a case where the distance L1 is set to a value greater than 2 mm.

[0107] In the gas sensor 1, the distance L1 from a position of the center of gravity CG1 of a portion of the spacer 70 in contact with the ceramic package 60 to the extension line of the axis of the sensor element 10 (gas sensor 1) is within 2 mm.

[0108] Therefore, the gas sensor 1 achieves the effect of remarkably preventing the ceramic case 60 from being fixed in a state where it is inclined 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.

[0109] Here, the gas sensor 1 is manufactured, for example, by the pre-assembly method as described above. However, if the ceramic housing 60 is tilted from the axial direction at a time of pre-assembly, the ceramic housing 60 is integrated with the sensor element 10 in the tilted state, that is, the state in which the ceramic housing 60 is tilted from the axial direction is fixed.

[0110] In view of the above, for example, by bringing the spacer 70 and the ceramic package 60 into contact with each other on the axis extension line at a time of pre-assembly, it is possible to prevent the ceramic package 60 from being positioned in a state where it is inclined from the axial direction in the contact member. Specifically, at a time of pre-assembly, the distance L1 from the center of gravity CG1 of a contact surface between the spacer 70 and the ceramic package 60 to the axis extension line is set to a value within 2 mm. Thereby, the gas sensor 1 can prevent the occurrence of an event in which "the ceramic package 60 is positioned in a state where it is inclined from the axial direction at a time of pre-assembly."

[0111] It should be noted that the Fig. 1 and Fig.2, a front end surface of the spacer 70 and a rear end surface of the ceramic package 60 are similar in area and shape, that is, they are substantially the same in area and shape.

[0112] By making a front end surface of the spacer 70 and a rear end surface of the ceramic package 60 substantially equal (similar) in area and shape, the gas sensor 1 achieves an effect as shown below. That is, in a case where a front end surface of the spacer 70 and a rear end surface of the ceramic package 60 are similar to each other, it is easy to bring the front end surface and the rear end surface into contact with each other on the extension line of the axis of the sensor element 10, for example, at a manufacturing stage of the gas sensor 1 and the like, compared to a case where the front end surface and the rear end surface are different from each other.In particular, by making a front end surface of the spacer 70 and a rear end surface of the ceramic package 60 similar to each other, it is easy to reduce the distance L1 from the center of gravity CG1 of a contact portion between the front end surface and the rear end surface to the extension line of the axis of the sensor element 10 (e.g., within 2 mm) during manufacturing or the like. Here, "similarity" of a front end surface of the spacer 70 and a rear end surface of the ceramic package 60 means that, for example, the front end surface and the rear end surface are circular or elliptical, and an area difference between them is about 40% or less of an area of ​​at least one of them.

[0113] However, in the gas sensor 1, it is not essential that a front end surface of the spacer 70 be similar to a rear end surface of the ceramic housing 60, and for example, it is not essential that the front end surface of the spacer 70 and the rear end surface of the ceramic housing 60 have substantially the same area and shape. In the gas sensor according to one aspect of the present invention, a front end surface of the spacer and a rear end surface of the ceramic housing may be similar to or different from each other.

[0114] In the gas sensor 1, for example, a front end surface of the spacer 70 may be smaller than a rear end surface of the ceramic case 60. Similarly, in the gas sensor 1, a front end surface of the spacer 70 may be larger than a rear end surface of the ceramic case 60. By making the front end surface of the spacer 70 larger than the rear end surface of the ceramic case 60, the gas sensor 1 achieves the effect described below. That is, in a case where a front end surface of the spacer 70 is larger than a rear end surface of the ceramic case 60, it is easy to sufficiently secure the contact area A1 between them, for example, in a manufacturing stage of the gas sensor 1, compared to a case where the front end surface is smaller than the rear end surface, and in particular, it is easy to limit the contact area A1 to 3 mm 2As a gas sensor according to one aspect of the present invention, an example in which a front end surface of the spacer in contact with the ceramic case (specifically, a rear end surface of the ceramic case) is made larger than a rear end surface of the ceramic case will be described later with reference to Fig. 4 described. (Regarding the type of contact between spacer and elastic body)

[0115] As in Fig.2, in the gas sensor 1, the contact area A2 between the spacer 70 (specifically, a rear end surface of the spacer 70) and the elastic body 50 (specifically, a front end surface of the elastic body 50) is set to be sufficiently large. Specifically, in the gas sensor 1, the contact area A2 is 25% or more of the total area of ​​a front end surface of the elastic body 50. However, in the gas sensor 1, it is not essential to set the contact area A2 to 25% or more of a total area of ​​a front end surface of the elastic body 50, and the contact area A2 may be less than 25% of a total area of ​​a front end surface of the elastic body 50.

[0116] The inventors of the present invention believe that it is effective to sufficiently secure the contact area A2 between the spacer 70 and the elastic body 50 to prevent the ceramic package 60 from being fixed in a state where it is tilted from the axial direction. For example, it is considered that when the contact area A2 is small, the force is likely to act in a direction inclined from the axial direction from the elastic body 50 to the spacer 70 compared to a case where the contact area A2 is large, and as a result, the ceramic package 60 in contact with the spacer 70 is also likely to be tilted from the axial direction.Furthermore, when the contact area A2 is small, the contact between the elastic body 50 and the spacer 70 is unstable compared to a case where the contact area A2 is large, and it is considered that the spacer 70 (particularly, an end surface of the spacer 70) is likely to be inclined from the axial direction, for example, in a case where an impact is applied to the gas sensor 1 and the like. Since the spacer 70 (particularly, an end surface of the spacer 70) is inclined from the axial direction, it is considered that the ceramic package 60 in contact with the spacer 70 (particularly, an end surface on the front end side of the spacer 70) is also inclined from the axial direction.In view of the above, the inventors of the present invention verified an area of ​​the contact area A2 between the spacer 70 and the elastic body 50 that is effective to prevent the ceramic package 60 from being fixed in a state where it is inclined from the axial direction. The inventors of the present invention confirmed that by setting the contact area A2 to 25% or more of a total area of ​​a front end surface of the elastic body 50, it is possible to remarkably prevent the ceramic package 60 from being fixed in a state where it is inclined from the axial direction, compared to a case where the contact area A2 is set to less than 25%.

[0117] In the gas sensor 1, the area of ​​a portion of a front end surface of the elastic body 50 in contact with the spacer 70, that is, the above-described contact area A2, is 25% or more of the total area of ​​the front end surface of the elastic body 50.

[0118] Therefore, the gas sensor 1 achieves the effect that it can remarkably prevent the ceramic case 60 from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A2 is less than 25% of a total area of ​​a front end surface of the elastic body 50.

[0119] Here, the gas sensor 1 is manufactured, as described above, by a swaging process, for example. In this swaging process, there is a possibility that the elastic body 50 is deformed, and stress is applied to the spacer 70 in a direction inclined to the axial direction. For example, in the swaging process, there is a possibility that a front end surface of the elastic body 50 is pushed out toward the front end side in a state inclined to the axial direction, exerting a stress on the spacer 70 in a direction inclined to the axial direction.When the contact area A2 between the spacer 70 and the elastic body 50 is small at the time of the die forming process, the spacer 70 is not stabilized because the elastic body 50 is soft and the load acts on the spacer 70 from the elastic body 50 in a direction inclined with respect to the axial direction, and the spacer 70 is likely to be inclined with respect to the axial direction. Since the spacer 70 (especially a front end surface of the spacer 70) is inclined from the axial direction, there is a possibility that the ceramic package 60 in contact with the spacer 70 is also inclined from the axial direction.

[0120] In view of the above, for example, by sufficiently securing the contact area A2 between the spacer 70 and the elastic body 50 in the above-described swaging process, the gas sensor 1 can prevent the ceramic housing 60 from being tilted from the axial direction. Specifically, by setting the contact area A2 to 25% or more of a total area of ​​a front end surface of the elastic body 50 in the swaging process, the gas sensor 1 can prevent the occurrence of an event in which "the ceramic housing 60 is tilted from the axial direction in the swaging process."

[0121] As in Fig.2, in the gas sensor 1, the elastic body 50 and the spacer 70 are in contact on a straight line obtained by axially extending the axis of the sensor element 10 (gas sensor 1) (i.e., an extension line of the axis). Specifically, in the gas sensor 1, the distance L2 from a position of the center of gravity CG2 of a "portion of the elastic body 50 (specifically, a front end surface of the elastic body 50) in contact with the spacer 70 (specifically, a rear end surface of the spacer 70)" to 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 practically uniformly distributed in a portion in contact with the spacer 70 (specifically, a rear end surface of the spacer 70) on a front end surface of the elastic body 50.It should be noted that for gas sensor 1, the distance L2 does not necessarily have to be within 2 mm and the distance can also be greater than 2 mm.

[0122] The inventors of the present invention considered that it is effective to bring the elastic body 50 and the spacer 70 into contact with each other on the extension line of the axis of the sensor element 10 (gas sensor 1) to prevent the ceramic package 60 from being fixed in a state of inclination from the axial direction. Specifically, the inventors of the present invention considered that if the distance L2 from the center of gravity CG2 of a contact surface between the elastic body 50 and the spacer 70 to the extension line of the axis can be sufficiently reduced, the ceramic package 60 can be effectively prevented from being fixed in a state of inclination from the axial direction.In view of the above, the inventors of the present invention verified the distance L2 from the center of gravity CG2 to the axis extension line, which effectively prevents the ceramic package 60 from being fixed in a state where it is inclined from the axial direction. As a result, the inventors of the present invention confirmed that by setting the distance L2 from the center of gravity CG2 to the axis extension line to a value within 2 mm, the ceramic package 60 can be remarkably prevented from being fixed in a state where it is inclined from the axial direction, compared to a case where the distance L2 is set to a value greater than 2 mm.

[0123] In the gas sensor 1, the distance L2 from a position of the center of gravity CG2 of a 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.

[0124] Therefore, the gas sensor 1 achieves the effect of remarkably preventing the ceramic case 60 from being fixed in a state where it is inclined 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.

[0125] Here, the gas sensor 1 is manufactured, as described above, for example, by the above-described swaging process. However, when the elastic body 50 is deformed in the swaging process and the load acts in a direction inclined from the axial direction from the elastic body 50 to the spacer 70, the ceramic housing 60 in contact with the spacer 70 may also be inclined from the axial direction.

[0126] In view of the above, for example, by bringing the elastic body 50 and the spacer 70 into contact with each other on the axis extension line during the swaging process, the gas sensor 1 can prevent the ceramic housing 60 from being tilted from the axial direction. Specifically, during the swaging process, the distance L2 from the center of gravity CG2 to the axis extension line is set to a value within 2 mm. This allows the gas sensor 1 to prevent the occurrence of an event where "the ceramic housing 60 is positioned in a state where it is tilted from the axial direction during the swaging process."

[0127] It should be noted that the Fig. 1 and Fig.2, a rear end surface of the spacer 70 and a front end surface of the elastic body 50 are similar in area and shape, that is, they are substantially the same in area and shape.

[0128] By making a rear end surface of the spacer 70 and a front end surface of the elastic body 50 substantially equal (similar) in area and shape, the gas sensor 1 exhibits the following effect. That is, in a case where a rear end surface of the spacer 70 and a front end surface of the elastic body 50 are similar to each other, it is easy to bring the rear end surface and the front end surface into contact with each other on the extension line of the axis of the sensor element 10, for example, at a manufacturing stage of the gas sensor 1 and the like, compared to a case where the rear end surface and the front end surface are different from each other.In particular, by making a rear end surface of the spacer 70 and a front end surface of the elastic body 50 similar to each other, it is easy to reduce the distance L2 from the center of gravity CG2 of a contact portion between the rear end surface and the front end surface to the extension line of the axis of the sensor element 10 (e.g., within 2 mm) during manufacturing or the like. "Similar" means that, for example, a difference in area between the rear end surface and the front end surface is approximately 40% or less of an area of ​​at least one of the rear end surface of the spacer 70 and the front end surface of the elastic body 50.

[0129] However, in the gas sensor 1, it is not essential that a rear end surface of the spacer 70 be similar to a front end surface of the elastic body 50, and for example, it is not essential that a rear end surface of the spacer 70 and a front end surface of the elastic body 50 have substantially the same area and shape. In the gas sensor according to one aspect of the present invention, a rear end surface of the spacer and a front end surface of the elastic body may be similar to or different from each other.

[0130] In the gas sensor 1, for example, a rear end surface of the spacer 70 may be larger than a front end surface of the elastic body 50. By making a rear end surface of the spacer 70 larger than a front end surface of the elastic body 50, the gas sensor 1 exhibits a downward effect. That is, in a case where a rear end surface of the spacer 70 is larger than a front end surface of the elastic body 50, it is easy to sufficiently secure the contact area A2 between them, for example, in a manufacturing stage of the gas sensor 1 and the like, compared to a case where the rear end surface is smaller than the front end surface.Particularly, in a case where a rear end surface of the spacer 70 is larger than a front end surface of the elastic body 50, it is easy to set the contact area A2 between the rear end surface and the front end surface to 25% or more of a total area of ​​the front end surface of the elastic body, compared with a case where the rear end surface is smaller than the front end surface.

[0131] Furthermore, in the gas sensor 1, a rear end surface of the spacer 70 may be smaller than a 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 desirably 25% or more of the total area of ​​a front end surface of the elastic body 50. Furthermore, the distance L2 from the center of gravity CG2 of a contact surface between the elastic body 50 and the spacer 70 to the extension line of the axis is desirably set to be sufficiently small, and in particular, the distance L2 is desirably set to be within 2 mm. (Regarding the direction of the end surface of each ceramic housing, spacer and elastic body)

[0132] In the gas sensor 1, the ceramic housing 60 is arranged along the axial direction, that is, the ceramic housing 60 is disposed inside the tubular body 20 (outer tube 22) in a state where it extends in the axial direction. According to the arrangement of the ceramic housing 60 along the axial direction, for example, a rear end surface of the ceramic housing 60 is orthogonal to the axial direction. Furthermore, in the gas sensor 1, a front end surface of the spacer 70, which is in contact with a rear end surface of the ceramic housing 60, is desirably also orthogonal to the axial direction.

[0133] In addition to a rear end surface of the ceramic package 60, a front end surface of the spacer 70 is also orthogonal to the axial direction, so that the gas sensor 1 can more effectively prevent the ceramic package 60 from being tilted from the axial direction when an impact is applied to the gas sensor 1.

[0134] The spacer 70 is desirably arranged along the axial direction, with a front end surface of the spacer 70 being orthogonal to the axial direction. In the gas sensor 1, a rear end surface of the spacer 70 is preferably orthogonal to the axial direction. Similarly, in the gas sensor 1, a front end surface of the elastic body 50 that contacts the spacer 70 (specifically, a rear end surface of the spacer 70) is also desirably perpendicular to the axial direction. Since the entire front end surface of the elastic body 50, as well as the rear end surface and the front end surface of the spacer 70, are orthogonal to the axial direction, the gas sensor 1 exhibits the following effect.That is, the gas sensor 1 can highly effectively prevent the ceramic package 60 from being tilted from the axial direction even in a case where, for example, an impact is applied to the gas sensor 1 and the like. <Erwägungen zur Konfiguration des Abstandshalters>

[0135] As described above, the gas sensor according to an aspect of the present invention solves a problem of the conventional gas sensor that "a ceramic case penetrates into an elastic body arranged on the rear end side of the ceramic case in a state of being inclined from the axial direction" by a configuration below. That is, the gas sensor according to an aspect of the present invention solves the above-described problem of the conventional gas sensor because the spacer, particularly the spacer in which a front end portion including a front end surface is sufficiently hard, is arranged on the rear end side of the ceramic case.In particular, the gas sensor according to one aspect of the present invention solves the above-described problem of the conventional gas sensor because the spacer "having a Young's modulus of 80 GPa or more at a front end portion" is arranged on the rear end side of the ceramic package.

[0136] For this reason, in the gas sensor according to one aspect of the present invention, the spacer disposed on the rear end side of the ceramic package (ie, in contact with a rear end surface of the ceramic package) only needs to have a Young's modulus of 80 GPa or more at least at a front end portion including a front end surface of the spacer. In the gas sensor according to the present invention, Fig. 1 and Fig.2, for example, the spacer 70 arranged on the rear end side of the ceramic package 60 (ie, in contact with a rear end surface of the ceramic package 60) has a Young's modulus of 80 GPa or more as a whole.

[0137] However, for the gas sensor according to one aspect of the present invention, it is not essential that the Young's modulus of the "entire" spacer disposed on the rear end side of the ceramic package be 80 GPa or more. As described above, in the gas sensor according to one aspect of the present invention, the spacer disposed on the rear end side of the ceramic package may have at least a Young's modulus of 80 GPa or more at a front end portion including a front end surface of the spacer. For example, in the gas sensor according to one aspect of the present invention, the spacer disposed on the rear end side of the ceramic package may be hard on the front end side and soft on the rear end side.Hereinafter, the gas sensor having the spacer disposed on the rear end side of the ceramic package and having a front end side that is hard and a rear end side that is soft, according to an aspect of the present invention, will be described with reference to FIG. Fig. 3 described.

[0138] Fig. 3 is a schematic cross-sectional view schematically illustrating an example of a main configuration of a gas sensor 1A according to a first variant. In Fig. 3, a left-right direction in the diagram is the axial direction (longitudinal direction) of the gas sensor 1A, the left side in the diagram is the front end side, and the right side in the diagram is the rear end side. The gas sensor 1A includes a spacer 70A, "which is arranged on the rear end side of the ceramic package 60, and the front end side is hard and the rear end side is soft." The spacer 70A shown in Fig. 3 is similar to the gas sensor 1A shown with reference to Fig.1 and Fig. 2, except that the spacer 70A is provided instead of the spacer 70. For this reason, a detailed description of a configuration other than the "spacer 70A" is omitted from the following description.

[0139] As in Fig.3, the spacer 70A in the gas sensor 1A includes a front end portion 71A and a rear end portion 72A. The spacer 70A is disposed within the tubular body 20 (outer tube 22) such that the front end portion 71A is located on the front end side in the axial direction, and the rear end portion 72A is located on the rear end side in the axial direction. The front end portion 71A and the rear end portion 72A have different hardness (softness) and, in particular, different Young's modulus from each other. 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.

[0140] Fig. 1 and Fig. 2 show an example of the gas sensor 1 in which the spacer 70 is a single component. In the Fig.In contrast, in the gas sensor 1A shown in FIG. 3, the spacer 70A disposed on the rear end side of the ceramic case 60 includes a plurality of constituent elements (constituent components). In the gas sensor according to one aspect of the present invention, the spacer disposed on the rear end side of the ceramic case may include a plurality of constituent elements (constituent components), and the Young's modulus of at least one front end portion only needs to be 80 GPa or more.In the gas sensor according to one aspect of the present invention, the spacer may include a front end side portion spacer arranged on the front end side in the axial direction and a rear end side portion spacer arranged on the rear end side, and the Young's moduli of the front end side portion spacer and the rear end side portion spacer may be different. In the gas sensor according to one aspect of the present invention, the spacer may have, for example, a multi-stage configuration (e.g., a two-stage configuration) including the above-described front end side portion spacer and the rear end side portion spacer. The spacer shown in . Fig.For example, the spacer 70A shown in FIG. 3 has a two-stage configuration with the front end portion 71A located on the front end side in the axial direction and the rear end portion 72A located on the rear end side. Note that the spacer 70A is not necessarily required to have a two-stage configuration, and the spacer 70A may further include an intermediate portion between the front end portion 71A and the rear end portion 72A, that is, it may have a configuration with three or more stages.

[0141] In the gas sensor 1A, the ceramic housing 60 is in contact with the spacer 70A arranged on the rear end side of the ceramic housing 60, specifically, with a front end surface of the spacer 70A (specifically, the front end portion 71A). In the spacer 70A, the Young's modulus of the front end portion 71A, including a front end surface with which the ceramic housing 60 (specifically, a rear end surface of the ceramic housing 60) is in contact, is 80 GPa or more. By setting the Young's modulus of the front end portion 71A, including a front end surface with which the ceramic housing 60 is in contact, of the spacer 70A to 80 GPa or more, the gas sensor 1A has an effect below. That is, the gas sensor 1A achieves the effect of being able to prevent the ceramic housing 60 from being inserted into a component (ie,the spacer 70A) arranged on the rear end side of the ceramic package 60 in a state in which it is inclined with respect to the axial direction.

[0142] As described above, the spacer 70A includes the front end portion 71A having a front end surface of the spacer 70A and the rear end portion 72A having a 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 in particular, 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.

[0143] 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. Then, in the gas sensor 1A, the spacer 70A is in contact with the elastic body 50 (specifically, a front end surface of the elastic body 50) at the rear end surface of the spacer 70A.

[0144] For this reason, when a front end surface of the elastic body 50 is inclined with respect to the axial direction in the gas sensor 1A, the inclination 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, when the soft rear end portion 72A of the spacer 70A is bent in contact with a front end surface of the elastic body 50, the inclination of a front end surface of the elastic body 50 can be absorbed in the rear end portion 72A of the spacer 70A.

[0145] The spacer 70A prevents the inclination of a front end surface of the elastic body 50 from being transmitted to the ceramic housing 60 via the spacer 70A, and the ceramic housing 60 from being tilted from the axial direction by the rear end portion 72A, which is softer and easier to bend than the front end portion 71A. For example, in a case where a front end surface of the elastic body 50 is tilted from the axial direction, stress in a direction inclined from the axial direction may be transmitted from a front end surface of the elastic body 50 to the ceramic housing 60, and the ceramic housing 60 may be tilted from the axial direction due to such stress. The spacer 70A prevents such an occurrence by the rear end portion 72A, which is softer and easier to bend than the front end portion 71A.That is, the spacer 70A prevents the occurrence of an event in which the ceramic housing 60 is tilted due to stress in a direction inclined from the axial direction of a front end surface of the elastic body 50 by absorbing the stress through the rear end portion 72A. Furthermore, the front end portion 71A of the spacer 70A has sufficient hardness, which can significantly prevent the ceramic housing 60 from penetrating the spacer 70A.

[0146] Therefore, the gas sensor 1A achieves an effect of being able to more effectively prevent the ceramic case 60 from penetrating into a member (ie, the spacer 70A) disposed on the rear end side of the ceramic case 60 in a state of being inclined with respect to the axial direction.

[0147] In a case where the spacer 70A is used to reduce the temperature rise of the elastic body 50 during use of the gas sensor 1A, each of the above-described front end portions 71A and rear end portions 72A can be configured as described below. That is, as the material of the front end portion 71A located on the front end side in the axial direction, ceramics having a higher melting point than that of resin are selected from the viewpoint of heat resistance, which is better than that of the rear end portion 72A. Preferably, a ceramic having a thermal conductivity of 32 W / m·K or less is selected, which is also suitable from the viewpoint of heat insulation properties in addition to heat resistance, and more preferably, alumina (thermal conductivity: 32 W / m·K) or steatite (thermal conductivity: 2 W / m·K) is selected.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 viewpoint of low thermal conductivity rather than ceramics and the like. The resin used for the rear end portion 72A is preferably polytetrafluoroethylene (PTFE, melting point: 327°C) or PFA (perfluoroalkoxyalkane, melting point: 310°C), which is a fluororesin. These resins have higher heat resistance than the rubber elastic body 50 and lower thermal conductivity. For example, PTFE has a thermal conductivity of 0.2 W / m·K and a maximum continuous use temperature (the maximum temperature during continued use at the maximum temperature) of 260°C.

[0148] That is, in the gas sensor 1A, at least a portion of the spacer 70A is made of ceramic, and for example, the front end portion 71A of the spacer 70A is made of ceramic. Ceramic has excellent heat resistance and generally has a higher melting point than resin. In the gas sensor 1A, the spacer 70A is arranged further to the front end side in the axial direction than the elastic body 50, and in particular, the front end portion 71A of the spacer 70A is arranged further to the front end side in the axial direction than the rear end portion 72A. When the front end portion 71A of the spacer 70A is made of ceramic with excellent heat resistance, the gas sensor 1A achieves the following effect.That is, the gas sensor 1A achieves the effect of being able to prevent the occurrence of an event in which the front end portion 71A of the spacer 70A is eroded by heat generated from a heat source on the front end side of the gas sensor 1A. However, it is not essential for the gas sensor 1A that the front end portion 71A of the spacer 70A be made of ceramic, and in the gas sensor 1A, a material having heat resistance can be appropriately used as a material of the front end portion 71A of the spacer 70A.

[0149] In the gas sensor 1A, the contact area A1(A) between the spacer 70A (in particular, the front end portion 71A) and the ceramic housing 60 is 3 mm 2or more, similar to the contact area A1 in the gas sensor 1. By setting the contact area A1(A) between the spacer 70A (specifically, a front end surface of the spacer 70A) and the ceramic package 60 (specifically, a rear end surface of the ceramic package 60) to 3 mm 2 or more, the gas sensor 1A achieves a following effect similar to that of the gas sensor 1. That is, the gas sensor 1A achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A1(A) between the spacer 70A and the ceramic package 60 is less than 3 mm 2 amounts.

[0150] In the gas sensor 1A, an area (contact area A2(A)) of a portion in contact with the spacer 70A (specifically, the rear end portion 72A) on a front end surface of the elastic body 50 is 25% or more of a total area of ​​a front end surface of the elastic body 50, similar to the contact area A2 in the gas sensor 1. By setting the contact area A2(A) between the elastic body 50 (specifically, a front end surface of the elastic body 50) and the spacer 70A (specifically, a rear end surface of the spacer 70A) to 25% or more of a total area of ​​the front end surface of the elastic body 50, the gas sensor 1A achieves an effect similar to that of the gas sensor 1.That is, the gas sensor 1A achieves the effect of being able to remarkably prevent the ceramic case 60 from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A2(A) is less than 25% of a total area of ​​a front end surface of the elastic body 50.

[0151] In the gas sensor 1A, the distance L1(A) from the position of the center of gravity CG1(A) of a portion of the spacer 70A in contact with the ceramic case 60 to the extension line of the axis of the sensor element 10 (gas sensor 1) is less than 2 mm, similar to the distance L1 in the gas sensor 1. The center of gravity CG1(A) is the center of mass when the mass is distributed practically uniformly in a portion in contact with the ceramic case 60 (specifically, a rear end surface of the ceramic case 60) on a front end surface of the spacer 70A (specifically, the front end portion 71A). By setting the distance L1(A) from a position of the center of gravity CG1(A) of a portion of the spacer 70A in contact with the ceramic case 60 to the extension line of the axis of the sensor element 10 to a value within 2 mm, the gas sensor 1A achieves an effect similar to that of the gas sensor 1.That is, the gas sensor 1A achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is inclined 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.

[0152] In the gas sensor 1A, the distance L2(A) from the position of the center of gravity CG2(A) of a 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 practically uniformly distributed in a portion in contact with the spacer 70A (specifically, a rear end surface of the spacer 70A) on a front end surface of the elastic body 50. By setting the distance L2(A) from a position of the center of gravity CG2(A) of a portion of the elastic body 50 in contact with the spacer 70A to the extension line of the axis of the sensor element 10 to a value within 2 mm, the gas sensor 1A achieves an effect similar to that of the gas sensor 1.That is, the gas sensor 1A achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is tilted from the axial direction, compared with a 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.

[0153] In the gas sensor 1A, a material of the elastic body 50 is fluororubber, similar to the elastic body 50 in the gas sensor 1. For this reason, the gas sensor 1A, similar to the gas sensor 1, achieves the effect of being able to maintain and improve the detection accuracy of the gas concentration by ensuring the sealability of the elastic body 50 under, for example, a high-temperature environment.

[0154] Note that in the Fig.3, a front end surface of the spacer 70A (front end portion 71A) and a rear end surface of the ceramic case 60 are similar in area and shape, that is, they are substantially the same in area and shape.

[0155] By making a front end surface of the spacer 70A and a rear end surface of the ceramic package 60 substantially equal (similar) in area and shape, the gas sensor 1A achieves an effect below. That is, in a case where a front end surface of the spacer 70A and a rear end surface of the ceramic package 60 are similar to each other, it is easy to bring the front end surface and the rear end surface into contact with each other on the extension line of the axis of the sensor element 10, for example, in a manufacturing stage of the gas sensor 1A and the like, compared to a case where the front end surface and the rear end surface are different from each other.In particular, by making a front end surface of the spacer 70A and a rear end surface of the ceramic package 60 similar to each other, it is easy to reduce the distance L1 from the center of gravity CG1 of a contact portion between the front end surface and the rear end surface to the extension line of the axis of the sensor element 10 (e.g., within 2 mm) during manufacturing or the like. Here, "similarity" of a front end surface of the spacer 70A and a rear end surface of the ceramic package 60 means that, for example, the front end surface and the rear end surface are circular or elliptical, and an area difference between them is about 40% or less of an area of ​​at least one of them.

[0156] However, in the gas sensor 1A, it is not essential that a front end surface of the spacer 70A be similar to a rear end surface of the ceramic housing 60, and for example, it is not essential that the front end surface and the rear end surface have substantially the same area and shape. In the gas sensor according to one aspect of the present invention, a front end surface of the spacer and a rear end surface of the ceramic housing may be similar to or different from each other.

[0157] For example, in the gas sensor 1A, a front end surface of the spacer 70A may be smaller than a rear end surface of the ceramic case 60. Similarly, in the gas sensor 1A, a front end surface of the spacer 70A may be larger than a rear end surface of the ceramic case 60. By making a front end surface of the spacer 70A larger than a rear end surface of the ceramic case 60, the gas sensor 1A achieves the effect described below. That is, in a case where a front end surface of the spacer 70A is larger than a rear end surface of the ceramic case 60, it is easy to sufficiently secure the contact area A1(A) between them, for example, in a manufacturing stage of the gas sensor 1A and the like, compared to a case where the front end surface is smaller than the rear end surface.Particularly, in a case where a front end surface of the spacer 70A is larger than a rear end surface of the ceramic package 60, it is easy to set the contact area A1(A) to 3 mm. 2 in a manufacturing stage of the gas sensor 1A and the like, compared with a case where the front end surface is smaller than the rear end surface.

[0158] Furthermore, the Fig. 3, a rear end surface of the spacer 70A and a front end surface of the elastic body 50 are similar in area and shape, that is, they are substantially the same in area and shape.

[0159] By making a rear end surface of the spacer 70A and a front end surface of the elastic body 50 substantially equal (similar) in area and shape, the gas sensor 1A exhibits the following effect. That is, in a case where a rear end surface of the spacer 70A and a front end surface of the elastic body 50 are similar to each other, it is easy to bring the rear end surface and the front end surface into contact with each other on the extension line of the axis of the sensor element 10, for example, at a manufacturing stage of the gas sensor 1A and the like, compared to a case where the rear end surface and the front end surface are different from each other.In particular, by making a rear end surface of the spacer 70A and a front end surface of the elastic body 50 similar to each other, it is easy to reduce the distance L2(A) from the center of gravity CG2(A) of a contact portion between the rear end surface and the front end surface to the extension line of the axis of the sensor element 10 (e.g., within 2 mm) during manufacturing or the like. "Similar" means that, for example, a difference in area between the rear end surface and the front end surface is approximately 40% or less of an area of ​​at least one of the rear end surface of the spacer 70A and the front end surface of the elastic body 50.

[0160] However, in the gas sensor 1A, it is not essential that a rear end surface of the spacer 70A be similar to a front end surface of the elastic body 50, and for example, it is not essential that a rear end surface of the spacer 70A and a front end surface of the elastic body 50 have substantially the same area and shape. In the gas sensor according to one aspect of the present invention, a rear end surface of the spacer and a front end surface of the elastic body may be similar to or different from each other.

[0161] For example, in the gas sensor 1A, a rear end surface of the spacer 70A may be larger than a front end surface of the elastic body 50. By making a rear end surface of the spacer 70A larger than a front end surface of the elastic body 50, the gas sensor 1A exhibits a downward effect. That is, in a case where a rear end surface of the spacer 70A is larger than a front end surface of the elastic body 50, it is easy to sufficiently secure the contact area A2(A) between them, for example, in a manufacturing stage of the gas sensor 1A and the like, compared to a case where the rear end surface is smaller than the front end surface.Particularly, in a case where a rear end surface of the spacer 70A is larger than a front end surface of the elastic body 50, it is easy to set the contact area A2(A) between the rear end surface and the front end surface to 25% or more of a total area of ​​the front end surface of the elastic body, compared with a case where the rear end surface is smaller than the front end surface.

[0162] Furthermore, in the gas sensor 1A, a rear end surface of the spacer 70A may be smaller than a 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 desirably 25% or more of the total area of ​​a front end surface of the elastic body 50. Furthermore, the distance L2(A) from the center of gravity CG2(A) of a contact surface between the elastic body 50 and the spacer 70A to the extension line of the axis is desirably set to be sufficiently small, and in particular, the distance L2(A) is desirably set to be within 2 mm. (Regarding the direction of the end surface of each of ceramic housing, spacer and elastic body)

[0163] In the gas sensor 1A, the ceramic housing 60 is arranged along the axial direction, that is, the ceramic housing 60 is arranged inside the tubular body 20 (outer tube 22) in a state where it extends in the axial direction. According to the arrangement of the ceramic housing 60 along the axial direction, for example, a rear end surface of the ceramic housing 60 is orthogonal to the axial direction. Furthermore, in the gas sensor 1A, a front end surface of the spacer 70A (specifically, the front end portion 71A) that contacts a rear end surface of the ceramic housing 60 is also desirably orthogonal to the axial direction.

[0164] In addition to a rear end surface of the ceramic housing 60, a front end surface of the spacer 70A (specifically, the front end portion 71A) is also orthogonal to the axial direction, so that the gas sensor 1A exhibits a trailing effect. That is, the gas sensor 1A can more effectively prevent the ceramic housing 60 from being tilted from the axial direction in a case where, for example, an impact is applied to the gas sensor 1A, etc.

[0165] Note 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 easier to bend than the front end portion 71A. Therefore, when a front end surface of the elastic body 50 is inclined from a direction orthogonal to the axial direction, the spacer 70A absorbs the inclination of the front end surface of the elastic body 50 by bending the rear end portion 72A and prevents the spacer 70A (specifically, a front end surface of the spacer 70A) from being inclined from the axial direction. Then, the gas sensor 1A can prevent the ceramic case 60 from being inclined from the axial direction by preventing the spacer 70A (specifically, a front end surface of the spacer 70A) from being inclined from the axial direction.Therefore, in the gas sensor 1A, a rear end surface of the spacer 70A (rear end portion 72A) does not need to be orthogonal to the axial direction. However, in the gas sensor 1A, a rear end surface of the spacer 70A may be orthogonal to the axial direction. Similarly, in the gas sensor 1A, a front end surface of the elastic body 50 that contacts the spacer 70A (specifically, a rear end surface of the spacer 70A) may be non-orthogonal to the axial direction or may be orthogonal to the axial direction. <Erwägungen zur Form des Abstandshalters>

[0166] Each of the gas sensors 1 and 1A described above includes the spacer "which is arranged on the rear end side of the ceramic case 60 and whose front end side is hard (specifically, with a Young's modulus of 80 GPa or more) and whose front end surface is similar to a rear end surface of the ceramic case."

[0167] By making a front end surface of the spacer similar to a rear end surface of the ceramic package, for example, by making the front end surface of the spacer and the rear end surface of the ceramic package substantially the same in area and shape, the gas sensor according to one aspect of the present invention achieves one of the effects described below. That is, in a case where a front end surface of the spacer and a rear end surface of the ceramic package are similar to each other, it is easy to bring the front end surface and the rear end surface into contact with each other on the extension line of the axis of the sensor element (gas sensor), for example, in a manufacturing stage of the gas sensor and the like, compared to a case where the front end surface and the rear end surface are different from each other.In particular, by making a front end surface of the spacer and a rear end surface of the ceramic package substantially equal in area and shape, it is easy to reduce the "distance from the center of gravity of a contact portion between the front end surface and the rear end surface to the extension line of the axis of the sensor element 10" (e.g., within 2 mm) in the manufacturing stage or the like.

[0168] However, in the gas sensor according to an aspect of the present invention, it is not essential that a front end surface of the spacer and a rear end surface of the ceramic case are similar, and for example, it is not essential that the front end surface and the rear end surface have substantially the same area and shape. In the gas sensor according to an aspect of the present invention, a front end surface of the spacer and a rear end surface of the ceramic case may be similar to or different from each other. In the gas sensor according to an aspect of the present invention, the spacer provided on the rear end side of the ceramic case (ie,In the gas sensor according to one aspect of the present invention, the shape of the spacer "which is arranged on the rear end side of the ceramic case 60 and whose front end side is hard" is not particularly limited, and for example, a front end surface of the spacer may be larger than a rear end surface of the ceramic case.Hereinafter, as a gas sensor according to an aspect of the present invention, an example of a gas sensor with a spacer “which has a front end surface larger than a rear end surface of the ceramic case 60, and in which the Y-oung's modulus of a front end portion including the front end surface is 80 GPa or more” will be described with reference to FIG. Fig. 4.

[0169] Fig. 4 is a schematic cross-sectional view schematically illustrating an example of a main configuration of the gas sensor 1B according to a second variant. In Fig.4, the left-right direction in the diagram is the axial direction (longitudinal direction) of the gas sensor 1B, and the left side in the diagram is the front end side, and the right side in the diagram is the rear end side. The gas sensor 1B includes a spacer 70B "which has a front end surface larger than a rear end surface of the ceramic package 60, and in which the Young's modulus of a front end portion including the front end surface is 80 GPa or more." The Fig. The gas sensor 1B shown in Figure 4 is similar to the one shown in Fig. 1 and Fig. 2, except that the spacer 70B is provided instead of the spacer 70. For this reason, a detailed description of a configuration other than the "spacer 70B" will be omitted from the following description.

[0170] In the gas sensor 1B, a front end surface of the spacer 70B is larger than a rear end surface of the ceramic case 60, which is in contact with the front end surface of the spacer 70B. In the gas sensor according to one aspect of the present invention, it is not essential that a front end surface of the spacer arranged on the rear end side of the ceramic case has a similar area and shape to the rear end surface of the ceramic case.

[0171] By making a front end surface of the spacer 70B larger than a rear end surface of the ceramic package 60, the gas sensor 1B achieves the following effect. That is, in a case where a front end surface of the spacer 70B is larger than a rear end surface of the ceramic package 60, it is easy to sufficiently secure a contact area A1(B) between them, for example, in a manufacturing stage of the gas sensor 1B and the like, compared to a case where the front end surface is smaller than the rear end surface. In particular, in a case where a front end surface of the spacer 70B is larger than a rear end surface of the ceramic package 60, it is easy to sufficiently secure the contact area A1(B) to 3 mm. 2 in a manufacturing stage of the gas sensor 1B and the like, compared with a case where the front end surface is smaller than the rear end surface.

[0172] In the gas sensor 1B, the ceramic housing 60 is in contact with the spacer 70B arranged on the rear end side of the ceramic housing 60, specifically, with a front end surface of the spacer 70B. In the spacer 70B, the Young's modulus of a front end portion including a front end surface with which the ceramic housing 60 (specifically, a rear end surface of the ceramic housing 60) is in contact is 80 GPa or more. That is, in the gas sensor 1B, the Young's modulus of the entire spacer 70B is 80 GPa or more.By setting the Young's modulus of the entire spacer 70B, particularly the Young's modulus of a front end portion of the spacer 70B, including a front end surface with which the ceramic case 60 is in contact, to 80 GPa or more, the gas sensor 1B achieves the following effect. That is, the gas sensor 1B achieves the effect of being able to prevent the ceramic case 60 from penetrating a component (i.e., the spacer 70B) disposed on the rear end side of the ceramic case 60 in a state of being inclined relative to the axial direction.

[0173] In the gas sensor 1B, the contact area A1(B) between the spacer 70B (specifically, a front end surface of the spacer 70B) and the ceramic package 60 (specifically, a rear end surface of the ceramic package 60) is 3 mm 2or more, similar to the contact area A1 in the gas sensor 1. By setting the contact area A1(B) between the spacer 70B (specifically, a front end surface of the spacer 70B) and the ceramic package 60 (specifically, a rear end surface of the ceramic package 60) to 3 mm 2 or more, the gas sensor 1B achieves a following effect similar to that of the gas sensor 1. That is, the gas sensor 1B achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A1(B) between the spacer 70B and the ceramic package 60 is less than 3 mm 2 amounts.

[0174] In the gas sensor 1B, an area (contact area A2(B)) of a portion in contact with the spacer 70B (specifically, a rear end surface of the spacer 70B) on a front end surface of the elastic body 50 is 25% or more of a total area of ​​a front end surface of the elastic body 50, similar to the contact area A2 in the gas sensor 1. By setting the contact area A2(B) between the elastic body 50 (specifically, a front end surface of the elastic body 50) and the spacer 70B (specifically, a rear end surface of the spacer 70B) to 25% or more of a total area of ​​the front end surface of the elastic body 50, the gas sensor 1B achieves the following effect, which is similar to the gas sensor 1.That is, the gas sensor 1B achieves the effect of being able to remarkably prevent the ceramic case 60 from being fixed in a state where it is inclined from the axial direction, compared with a case where the contact area A2(B) is less than 25% of a total area of ​​a front end surface of the elastic body 50.

[0175] In the gas sensor 1B, the distance L1(B) from the position of the center of gravity CG1(B) of a portion of the spacer 70B in contact with the ceramic case 60 to the extension line of the axis of the sensor element 10 (gas sensor 1) is less than 2 mm, similar to the distance L1 in the gas sensor 1. The center of gravity CG1(B) is the center of mass when the mass in a portion in contact with the ceramic case 60 (specifically, a rear end surface of the ceramic case 60) is practically uniformly distributed on a front end surface of the spacer 70B. By setting the distance L1(B) from a position of the center of gravity CG1(B) of a portion of the spacer 70B in contact with the ceramic case 60 to the extension line of the axis of the sensor element 10 to a value within 2 mm, the gas sensor 1B achieves an effect similar to that of the gas sensor 1.That is, the gas sensor 1B achieves the effect of being able to remarkably prevent the ceramic package 60 from being fixed in a state where it is inclined from the axial direction, compared with a 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.

[0176] In the gas sensor 1B, the distance L2(B) from the position of the center of gravity CG2(B) of a 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 practically uniformly distributed in a portion in contact with the spacer 70B (specifically, a rear end surface of the spacer 70B) on a front end surface of the elastic body 50. By setting the distance L2(B) from a position of the center of gravity CG2(B) of a portion of the elastic body 50 in contact with the spacer 70B to the extension line of the axis of the sensor element 10 to a value within 2 mm, the gas sensor 1B achieves an effect smaller than that of the gas sensor 1.That is, the gas sensor 1B achieves the effect of being able to remarkably prevent the ceramic case 60 from being fixed in a state where it is inclined from the axial direction, compared with a 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.

[0177] In the gas sensor 1B, a material of the elastic body 50 is fluororubber, similar to the elastic body 50 in the gas sensor 1. For this reason, the gas sensor 1B, similar to the gas sensor 1, achieves the effect of being able to maintain and improve the detection accuracy of the gas concentration by ensuring the sealability of the elastic body 50 under, for example, a high-temperature environment.

[0178] In the gas sensor 1B, at least a portion of the spacer 70B is made of ceramic, and the entire spacer 70B is made of ceramic. Ceramic has excellent heat resistance and generally has a higher melting point than resin. In the gas sensor 1B, the spacer 70B is arranged further to the front end side in the axial direction than the elastic body 50. When the spacer 70B is made of ceramic with excellent heat resistance, the gas sensor 1B achieves the effect described below. That is, the gas sensor 1B achieves the effect of being able to prevent the occurrence of an event in which the spacer 70B is eroded by heat generated from a heat source on the front end side of the gas sensor 1B.However, it is not essential for the gas sensor 1B that the spacer 70B is made of ceramic, and in the gas sensor 1B, a material having heat resistance may be used as the material of the spacer 70B.

[0179] In the Fig. 4, a rear end surface of the spacer 70B and a front end surface of the elastic body 50 are similar in area and shape, that is, they are substantially the same in area and shape.

[0180] By making a rear end surface of the spacer 70B and a front end surface of the elastic body 50 substantially equal (similar) in area and shape, the gas sensor 1B exhibits the following effect. That is, in a case where a rear end surface of the spacer 70B and a front end surface of the elastic body 50 are similar to each other, it is easy to bring the rear end surface and the front end surface into contact with each other on the extension line of the axis of the sensor element 10, for example, in a manufacturing stage of the gas sensor 1B and the like, compared to a case where the rear end surface and the front end surface are different from each other.In particular, by making a rear end surface of the spacer 70B and a front end surface of the elastic body 50 similar to each other, it is easy to reduce the distance L2(B) from the center of gravity CG2(B) of a contact portion between the rear end surface and the front end surface to the extension line of the axis of the sensor element 10 (e.g., within 2 mm) during manufacturing or the like. "Similar" means that, for example, a difference in area between the rear end surface and the front end surface is approximately 40% or less of an area of ​​at least one of the rear end surface of the spacer 70B and the front end surface of the elastic body 50.

[0181] However, in the gas sensor 1B, it is not essential that a rear end surface of the spacer 70B be similar to a front end surface of the elastic body 50, and for example, it is not essential that a rear end surface of the spacer 70B and a front end surface of the elastic body 50 have substantially the same area and shape. In the gas sensor according to one aspect of the present invention, a rear end surface of the spacer and a front end surface of the elastic body may be similar to or different from each other.

[0182] For example, in the gas sensor 1B, a rear end surface of the spacer 70B may be larger than a front end surface of the elastic body 50. By making a rear end surface of the spacer 70B larger than a front end surface of the elastic body 50, the gas sensor 1B exhibits a downward effect. That is, in a case where a rear end surface of the spacer 70B is larger than a front end surface of the elastic body 50, it is easy to sufficiently secure the contact area A2(B) between them, for example, in a manufacturing stage of the gas sensor 1B and the like, compared to a case where the rear end surface is smaller than the front end surface.Particularly, in a case where a rear end surface of the spacer 70B is larger than a front end surface of the elastic body 50, it is easy to set the contact area A2(B) between the rear end surface and the front end surface to 25% or more of a total area of ​​the front end surface of the elastic body, compared with a case where the rear end surface is smaller than the front end surface.

[0183] Furthermore, in the gas sensor 1B, a rear end surface of the spacer 70B may be smaller than a 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 desirably 25% or more of the total area of ​​a front end surface of the elastic body 50. Furthermore, the distance L2(B) from the center of gravity CG2(B) of a contact surface between the elastic body 50 and the spacer 70B to the extension line of the axis is desirably set to be sufficiently small, and in particular, the distance L2(B) is desirably set to be within 2 mm. [Feature]

[0184] As described above, the gas sensor (1, 1A, 1B) according to one aspect of the present invention includes the sensor element 10, the terminal fitting 30, the ceramic housing 60, the tubular body 20, the elastic body 50, and the spacer (70, 70A, 70B). The sensor element 10 extends in the axial direction, has the detection unit 11 on the front end side and the connector electrode 12 on the rear end side. The terminal fitting 30 extends in the axial direction and has the 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 housing 60 accommodates the connector electrode 12 of the sensor element 10 and the element contact portion 31 of the terminal fitting 30.The tubular body 20 is a tubular member in which the sensor element 10, the connector 30, and the ceramic housing 60 are arranged, and an opening end is formed. The elastic body 50 is arranged to seal an opening end (an opening end on the rear end side) of the tubular body 20.

[0185] The spacer (70, 70A, 70B) according to an aspect of the present invention is arranged between the ceramic case 60 and the elastic body 50 in the axial direction of the sensor element 10 (gas sensor (1, 1A, 1B)). The spacer contacts the ceramic case 60 at a front end surface and the elastic body 50 at a rear end surface. In the spacer according to an aspect of the present invention, the Young's modulus of at least a front end portion including a front end surface is 80 GPa or more. For example, the Young's modulus of each of the entire spacers 70 and 70B is 80 GPa or more. Furthermore, the spacer 70A includes the front end portion 71A having a Young's modulus of 80 GPa or more and the rear end portion 72A having a Young's modulus of less than 80 GPa.

[0186] The inventors of the present invention considered that it is possible to prevent the ceramic housing 60 from intruding into the elastic body 50 by disposing the spacer (70, 70A, 70B) between the ceramic housing 60 and the elastic body 50. In view of this, in the gas sensor according to one aspect of the present invention, the spacer (70, 70A, 70B) is disposed between the ceramic housing 60 and the elastic body 50.

[0187] In order to prevent the ceramic housing 60 from penetrating a component arranged at the rear end side of the ceramic housing 60, the inventors of the present invention considered that it is effective to sufficiently harden a portion at the front end side in the axial direction of the component arranged at the rear end side. Here, as described above, in the gas sensor according to one aspect of the present invention, the spacer (70, 70A, 70B) is arranged between the ceramic housing 60 and the elastic body 50. In order to prevent the ceramic housing 60 from penetrating the spacer (70, 70A, 70B) (particularly, a front end portion of the spacer), the inventors of the present invention achieved hardness (softness) imparted to the front end portion of the spacer through an experiment (an example will be described later).As a result, the inventors of the present invention have confirmed that by setting the Young's modulus of the front end portion of the above-described spacer to 80 GPa or more, it is possible to remarkably prevent the ceramic package 60 from penetrating into the spacer (particularly, a front end portion of the spacer) compared with a case where the Young's modulus is set to less than 80 GPa.

[0188] In the gas sensor according to one aspect of the present invention, the ceramic housing 60 is in contact with the spacer (70, 70A, 70B) disposed at the rear end side of the ceramic housing 60, particularly with a front end surface of the spacer (70, 70A, 70B). Then, the Young's modulus of a front end portion including a front end surface of the spacer (70, 70A, 70B) is 80 GPa or more, which is a sufficient hardness capable of remarkably preventing the ceramic housing 60 from penetrating the spacer (particularly the front end portion of the spacer).

[0189] For this reason, in the gas sensor according to one aspect of the present invention, an event such as “the ceramic case 60 penetrates into the above-described spacer disposed on the rear end side of the ceramic case 60 in a state of being inclined from the axial direction, and such a state is fixed” does not occur.

[0190] Therefore, the gas sensor according to an aspect of the present invention can prevent the ceramic case 60 from penetrating into a component (ie, the spacer (70, 70A, 70B)) arranged on the rear end side of the ceramic case 60 in a state of being inclined with respect to the axial direction. [Variation]

[0191] Although the embodiment of the present invention is described above, the above description of the embodiment is merely an example of the present invention in all respects. Various improvements and modifications can be made to the above embodiment. With respect to each constituent element of the above embodiment, omission, replacement, and addition of the constituent element can be carried out as appropriate. Furthermore, the shape and dimension of each constituent element of the above embodiment can be changed according to the embodiment. For example, a change can be made below.Note that in the following description, a similar reference numeral is used for a constituent element similar to that of the above embodiment, and the description for a point similar to the above embodiment is omitted accordingly. The following variations can be combined as appropriate.

[0192] In the gas sensor (e.g., the above-described gas sensors 1, 1A, or 1B) according to one aspect of the present invention, the shape of the spacer (70, 70A, 70B) disposed between the elastic body (50) and the ceramic case (60) is not particularly limited. The spacer may, for example, have a cylindrical shape, a truncated cone shape, or a shape in which one or more cylinders and one or more truncated cones are combined and arranged in the axial direction. Furthermore, in at least a part of the spacer, a length in a direction orthogonal to the axial direction (e.g., a diameter in a direction orthogonal to the axial direction) may change continuously or discontinuously along the axial direction.Furthermore, in the spacer, a front end surface and a rear end surface may have substantially the same shape, an area of ​​a front end surface may be smaller than an area of ​​a rear end surface, or an area of ​​a front end surface may be larger than an area of ​​a rear end surface.

[0193] Furthermore, a front end surface of the spacer may be similar to a rear end surface of the ceramic package. For example, a front end surface of the spacer and a rear end surface of the ceramic package may be substantially the same in area and shape. Furthermore, a front end surface of the spacer and a rear end surface of the ceramic package may differ from each other. For example, the front end surface and the rear end surface may differ from each other in at least one of the two properties of area and shape.

[0194] Similarly, a rear end surface of the spacer may be similar to a front end surface of the elastic body, and for example, a rear end surface of the spacer and a front end surface of the elastic body may be substantially the same in area and shape. Furthermore, a rear end surface of the spacer and a front end surface of the elastic body may be different from each other, that is, the rear end surface and the front end surface may differ from each other in at least one of area and shape. [Example]

[0195] To verify the effect of the present invention (particularly the durability performance of the connector), the present inventors fabricated a gas sensor according to the following levels (Examples) 1 to 4 and conducted a high-acceleration limit test (HALT test). However, the present invention is not limited to the following levels (Examples). [Table 1] level Component in contact with the ceramic housing at the rear end of the ceramic housing Young's modulus Evaluation 1 Elastic body 7 GPa × 2 spacers 65GPa × 3 spacers 80GPa ○ 4 spacers 120GPa ○

[0196] A Level 1 gas sensor is a conventional gas sensor as disclosed in the above-described JP 2014-196917 A, that is, a gas sensor in which no spacer is disposed between a ceramic housing and an elastic body. Specifically, in the Level 1 gas sensor, an elastic body is disposed on the rear end side of a ceramic housing in an axial direction of the gas sensor (axial direction of a sensor element), and specifically, the elastic body is in contact with the ceramic housing at the rear end of the ceramic housing.

[0197] Each of the gas sensors of levels 2 to 4 is a gas sensor that has a Fig.1, that is, a gas sensor in which a spacer is disposed between a ceramic case and an elastic body. Specifically, in the gas sensor of levels 2 to 4, a spacer is disposed on the rear end side in an axial direction of a ceramic case, and specifically, the spacer is in contact with the ceramic case at a rear end of the ceramic case. However, the gas sensors of levels 2 to 4 differ in the Young's modulus of a spacer that abuts a ceramic case at a rear end of the ceramic case.

[0198] That is, in the level 2 gas sensor, the Young's modulus of a spacer is 65 GPa, that is, the spacer in contact with a ceramic package at a rear end of the ceramic package has a Young's modulus of less than 80 GPa. On the other hand, in the level 3 to 4 gas sensors, the Young's modulus of a spacer is 80 GPa or more, that is, a spacer in contact with a ceramic package at a rear end of the ceramic package has a Young's modulus of 80 GPa or more. Specifically, in the level 3 gas sensor, the Young's modulus of a spacer is 80 GPa. In the level 4 gas sensor, the Young's modulus of a spacer is 120 GPa.

[0199] The inventors of the present invention conducted a high-acceleration limit test (HALT test) for the gas sensor according to each of levels 1 to 4 to compare the durability performance of a connector attached to a ceramic package and connected to a sensor element. That is, a HALT test in which each temperature condition and each acceleration condition were tested in the Fig. 5 was performed on the gas sensor according to each of the levels 1 to 4 (a plurality of gas sensors according to the levels).

[0200] Fig. Fig. 5 is a diagram showing each change (sequence) of a temperature condition and an acceleration condition in a HALT test (Durability Comparison Test) conducted by the inventors of the present invention on the gas sensor according to each of levels 1 to 4. In the Fig.In the diagram shown in Figure 5, a change in a temperature condition is indicated by a dotted line, and as in Fig. As shown in Figure 5, a temperature condition is changed in a range from "-90°C" to "190°C". Furthermore, in the Fig. 5, a change in an acceleration condition is indicated by a solid line, and as in Fig. 5, an acceleration condition is changed in a range from “10 Grms” to “70 Grms”.

[0201] Such a HALT test was performed on a plurality of gas sensors according to the levels, and after performing the HALT test (for example, at a time of time = 200, in other words, at a time of acceleration = 40 Grms), the presence or absence of breakage of a terminal attached to a ceramic housing was checked. That is, the above-described HALT test was performed on a plurality of gas sensors according to level 1, and after performing the HALT test, the presence or absence of breakage of a terminal of a plurality of gas sensors was checked. Similarly, the above-described HALT test was performed on a plurality of gas sensors according to levels 2 to 4, and after performing the HALT test, the presence or absence of breakage of a terminal of a plurality of gas sensors was checked.

[0202] In Table 1, the rating "O (Extremely Good)" indicates that a connector attached to a ceramic housing was not damaged in all of a plurality of gas sensors according to the levels. The rating "× (Poor)" indicates that a connector breakage was confirmed in one or more of the plurality of gas sensors according to the levels.

[0203] It should be noted that in the HALT test described above, a variety of gas sensors are subjected to temperature and acceleration (vibration) stress, depending on the level, that exceeds the actual use conditions of the gas sensor. Therefore, even if the rating in Table 1 is "× (poor)", it should be noted that such a rating of "×" does not mean that the gas sensor at the "×" rated level is unsuitable for actual use.

[0204] The conventional Level 1 gas sensor (the gas sensor in which no spacer is placed between a ceramic housing and an elastic body) was rated "× (poor)". Furthermore, the Level 2 gas sensor (the gas sensor in which a spacer is placed between a ceramic housing and an elastic body, and the Young's modulus of the spacer is less than 80 GPa) was rated "× (poor)".

[0205] On the other hand, all gas sensors of levels 3 to 4 (the gas sensor in which a spacer is placed between a ceramic case and an elastic body and the Young's modulus of the spacer is 80 GPa or more) were rated as "O (extremely good)".

[0206] Therefore, the inventors of the present invention have confirmed the following event through the above-described HALT test and test results (evaluation). That is, the inventors of the present invention have confirmed that the possibility of breakage of a terminal attached to a ceramic package can be reduced by disposing a spacer between the ceramic package and an elastic body, and by having a Young's modulus of the spacer of 80 GPa or more. List of reference symbols 1, 1A, 1B gas sensor 10 Sensor element 11 Recording unit 12 connector electrode 20 Tubular body 30 connector 31 Element contact section 50 Elastic Body 60 ceramic housings 70, 70A, 70B spacers QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2014-196917 A [0002, 0003, 0196]

Claims

[1] Gas sensor, comprising: a sensor element extending in an axial direction, having a detection unit at a front end side, and having a connector electrode at a rear end side; a terminal extending in the axial direction and having an element contact portion electrically connected to the connector electrode at a front end side; a ceramic housing accommodating the connector electrode and the element contact portion; a tubular body in which the sensor element, the connector and the ceramic housing are arranged, and an opening end is formed; an elastic body arranged to seal the opening end; and a spacer disposed between the ceramic case and the elastic body in the axial direction, in contact with the ceramic case at an end surface on a front end side in the axial direction, in contact with the elastic body at an end surface on a rear end side in the axial direction, and having a Young's modulus of 80 GPa or more at least at a front end portion including an end surface on the front end side. [2] The gas sensor according to claim 1, wherein in the spacer, the Young's modulus of a rear end portion including an end surface on the rear end side is smaller than the Young's modulus of the front end portion. [3] Gas sensor according to claim 1 or 2, wherein the contact area between the spacer and the ceramic housing is 3 mm 2 or more. [4] The gas sensor according to claim 1 or 2, wherein the area of ​​a portion in contact with the spacer in an end surface on the front end side of the elastic body is 25% or more of the total area of ​​an end surface on the front end side of the elastic body. [5] The gas sensor according to claim 1 or 2, wherein a distance from a position of a center of gravity of a portion in contact with the ceramic case on the end surface on the front end side of the spacer, which is a center of gravity when the mass is distributed substantially uniformly to a portion in contact with the ceramic case on an end surface on the front end side of the spacer, to a straight line obtained by extending an axis of the sensor element in the axial direction is within 2 mm. [6] The gas sensor according to claim 1 or 2, wherein a distance from a position of a center of gravity of a portion in contact with the spacer on an end surface on the front end side of the elastic body, which is a center of gravity when the mass is distributed substantially uniformly to a portion in contact with the spacer on the end surface on the front end side of the elastic body, to a straight line obtained by extending an axis of the sensor element in the axial direction is within 2 mm. [7] The gas sensor according to claim 1 or 2, wherein a material of the elastic body is fluororubber. [8] A gas sensor according to claim 1 or 2, wherein at least a portion of the spacer is constructed of ceramic.

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