JP2016188847A - Gas sensor, and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor whose base part made of macromolecular material can be easily fitted to the rear end side of a main constituent metal fitting thereby to enhance its productivity and reduce the required number of its components, and a manufacturing method for the gas sensor.SOLUTION: A gas sensor 200 is equipped with a gas sensor element 10 that extends in the direction of its axis O and has on its tip side a detector 11, a main constituent metal fitting 50 that holds the gas sensor element and a base part 120 that is made of macromolecular material, is arranged on the rear end side of the main constituent metal fitting and covers the rear end 12 side of the gas sensor element. The gas sensor is further equipped with a metal-made cylinder 110 that connects the main constituent metal fitting and the base part, having the base part integrated with whose own ear end side and whose own tip side is exposed from the base part to constitute an exposed part 110p. Part of the exposed part of the cylinder is connected to the main constituent metal fitting, and the base part is arranged isolated from the main constituent metal fitting.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gas sensor including a gas sensor element that detects the concentration of a gas to be detected and a method for manufacturing the gas sensor.

  A gas sensor is attached to an intake system (for example, an intake pipe or an intake manifold) or an exhaust system of an internal combustion engine such as a diesel engine or a gasoline engine, and a concentration of a specific gas is monitored to control a combustion state or the like. And as a gas sensor generally used for such control, the structure which hold | maintains a gas sensor element inside a metal shell, and covers the rear-end side of a gas sensor element with a metal cover is taken. In addition, a technique has been developed that facilitates manufacture and assembly by attaching a resin base portion to the rear end side of the metal shell instead of a metal cover (Patent Document 1).

Japanese Patent No. 3873390 (FIG. 1)

However, in the case of the gas sensor disclosed in Patent Document 1, the base metal part is provided with a flange, the metal shell opposite to the base metal part is provided with a caulking part, and the flange is caulked and fixed to the caulking part. Is connected. For this reason, the structure of the metal shell becomes complicated, and there is a problem that it is difficult to reduce the size of the gas sensor because the metal shell is large in diameter because the caulking portion is provided. Further, when the base body part and the metal shell are in contact with each other, the heat of the metal shell may be directly transmitted to the base body part to cause thermal deterioration of the base body part.
Therefore, the present invention provides a gas sensor and a gas sensor manufacturing method that can easily attach a base portion made of a polymer material to the rear end side of the metal shell, improve productivity, and reduce the number of parts. Objective.

In order to solve the above problems, a gas sensor of the present invention includes a gas sensor element extending in the axial direction and having a detection unit for detecting a specific gas component in a gas to be measured on its tip side, and a radial direction of the gas sensor element A gas sensor comprising: a metal shell that surrounds the periphery and holds the gas sensor element; and a base portion made of a polymer material that is disposed on the rear end side of the metal shell and covers the rear end side of the gas sensor element. A metal cylinder connecting the metal shell and the base body, the base body is integrated on the rear end side of the metal shell, and the front end side of the base metal is exposed from the base part to form an exposed portion. A cylindrical body is further provided, a part of the exposed portion of the cylindrical body is connected to the metal shell, and the base portion is disposed apart from the metal shell.
According to this gas sensor, a base part is integrated with a metal cylinder by insert molding or the like, and the metal shell and the base part are connected via the cylinder, thereby forming a complicated structure in the metal shell and the base part. Without providing, the base portion can be easily attached to the rear end side of the metal shell, and the productivity can be improved. Further, by integrating the base portion into the cylindrical body by insert molding or the like, the number of parts can be reduced, the cost can be reduced, and the productivity can be further improved. Further, for example, in order to connect the metal shell and the base body, a flange is provided in the base metal body, and the metal shell has a large diameter as in the case where the metal shell is provided with a caulking portion for caulking and fixing the flange. Therefore, the gas sensor can be downsized. Furthermore, by disposing the metallic shell and the base portion apart via the cylinder, it is possible to suppress the heat of the metallic shell from being directly transmitted to the base portion and causing the thermal deterioration of the base portion.

In the gas sensor of the present invention, the exposed portion of the cylindrical body may extend parallel to the axial direction.
According to this gas sensor, after the base portion is integrated with the cylindrical body by insert molding or the like, the cylindrical body (exposed portion thereof) can be easily removed from the mold, and productivity can be improved.

In the gas sensor of the present invention, the rear end portion of the cylindrical body may have a protruding portion that protrudes in the radial direction inside the base portion.
According to this gas sensor, the cylindrical body can be prevented from falling off from the base portion in the axial direction.

In the gas sensor of the present invention, the base portion has a connector portion that extends in a direction intersecting the axial direction and can be removed from an external device, and the connector portion is electrically connected to the external device. A connector terminal may be included, and the connector portion may be integrated with the connector terminal.
According to this gas sensor, there is no need for a separate part for holding the connector terminal on the base part, further reducing the number of parts, further reducing the cost, and simultaneously fixing the cylindrical body and the connector terminal at the time of manufacturing the base part. Therefore, productivity can be further improved. Further, since the connector portion extends in a direction intersecting with the axial direction, when the gas sensor is attached to the intake system, the protruding length of the gas sensor to the outside of the intake system can be shortened. Thereby, the space | interval of a bonnet and a gas sensor can be ensured and the safety | security when a vehicle collides can be improved.

The gas sensor of this invention WHEREIN: You may have the sealing member arrange | positioned inside the said base | substrate part so that the side surface of the said cylinder may be contact | connected.
According to this gas sensor, even if the gas sensor is exposed to a high temperature and the base portion expands more than the cylindrical body, the sealing member seals the gap between the base portion and the cylindrical body, so that airtightness can be ensured.

In the gas sensor according to the aspect of the invention, the base portion includes a receiving groove that extends toward a rear end side with an opening at the front end thereof and that faces at least a part of the side surface of the cylindrical body, and the seal member is formed in the receiving groove. It may be housed and may further include a lid portion that closes the housing groove on the tip side of the seal member.
If the gas sensor is cold when it is transported, etc., the seal member may contract and fall out of the receiving groove. In order to prevent this, if the seal member is excessively compressed and accommodated in the accommodation groove, the seal member may sag due to a creep phenomenon over time, and the sealing performance may be deteriorated. Therefore, the sealing member can be prevented from falling off by closing the housing groove with the lid on the tip side of the sealing member.

The gas sensor of the present invention may further include a connection terminal that is electrically connected to the gas sensor element, and the base portion may integrally include a separator portion that holds the connection terminal.
According to this gas sensor, there is no need for a separator as a separate part for holding the connection terminal and a separate member (for example, a metal cylindrical holding metal fitting) for attaching the separator to the base portion, further reducing the number of parts and cost. Can be further reduced, and productivity can be further improved.

In the gas sensor of the present invention, the connection terminal may be fitted into the separator portion.
Since the connection terminal has a complicated shape, it is difficult to integrate the base portion around the connection terminal by insert molding or the like. Then, it can assemble easily by fitting a connecting terminal to a separator part.

The gas sensor manufacturing method of the present invention includes a gas sensor element that extends in the axial direction and has a detection unit for detecting a specific gas component in the gas to be measured on its tip side, and surrounds the circumference of the gas sensor element in the radial direction. A gas sensor manufacturing method comprising: a metal shell that holds the gas sensor element; and a base portion made of a polymer material that is disposed on a rear end side of the metal shell and covers the rear end side of the gas sensor element, A metal cylinder, wherein the base body part is insert-molded on the rear end side of the metal body, and the base end part is exposed from the base body part to form an exposed part, and the base body part is the metal shell. A part of the exposed portion of the cylindrical body is connected to the metal shell so as to be separated from the metal shell.
According to this gas sensor manufacturing method, the metal shell and the base body are connected to each other through a metal cylinder in which the base body is integrated with the cylinder by insert molding. Without providing the base portion, the base portion can be easily attached to the rear end side of the metal shell, and the productivity can be improved. Further, by integrating the base portion into the cylindrical body by insert molding or the like, the number of parts can be reduced, the cost can be reduced, and the productivity can be further improved. Further, for example, in order to connect the metal shell and the base body, a flange is provided in the base metal body, and the metal shell has a large diameter as in the case where the metal shell is provided with a caulking portion for caulking and fixing the flange. Therefore, the gas sensor can be downsized. Furthermore, by disposing the metallic shell and the base portion apart via the cylinder, it is possible to suppress the heat of the metallic shell from being directly transmitted to the base portion and causing the thermal deterioration of the base portion.

  According to this invention, the base portion made of a polymer material can be easily attached to the rear end side of the metal shell, and a gas sensor with improved productivity and a reduced number of parts can be obtained.

It is a perspective view which shows the structure of the gas sensor which concerns on embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is process drawing which assembles a connection terminal to a base part. It is a fragmentary sectional view showing the modification of a cylinder. It is sectional drawing which shows the example which provided the sealing member in the inside of the base | substrate part of a gas sensor. It is sectional drawing which shows another example which provided the sealing member in the inside of the base | substrate part of a gas sensor.

Hereinafter, embodiments of the present invention will be described.
1 is a perspective view of a gas sensor 200 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a process diagram for assembling the connection terminal 30 to the base body 120. In FIG. 3, the base portion 120 is displayed with the front end side facing up.
Note that the axis O direction (indicated by a one-dot chain line) of the gas sensor element 10 is shown as a vertical direction, and the rear end portion 12 side of the gas sensor element 10 is on the rear end side of the gas sensor element 10 (and the gas sensor) and the opposite side thereof. The detection part 11 (refer FIG. 2) side of a certain gas sensor element 10 is demonstrated as the front end side of the gas sensor element 10 (and gas sensor). A direction perpendicular to the direction of the axis O is appropriately referred to as a “radial direction”.
In FIG. 2, for the sake of simplicity, only three connection terminals are displayed and only one connector terminal is displayed. Actually, however, there are a plurality of connection terminals and connector terminals (an embodiment of the present invention). Then, five each).

As shown in FIG. 1, the gas sensor 200 includes a gas sensor element 10 (not shown), an outer protector 100 that covers the detection unit 11 of the gas sensor element 10, a metal shell 50 that holds the gas sensor element 10, It has the base | substrate part 120 which consists of a polymeric material arrange | positioned at the rear end side, and the metal cylinder 110 which connects the metal shell 50 and the base | substrate part 120. FIG.
The base 120 has a cylindrical main body 123 whose rear end is closed, a semicircular flange 121 extending radially outward from one side of the main body 123, and a diameter from the other side of the main body 123. And a substantially rectangular connector portion 125 extending outward in the direction. The flange portion 121 and the connector portion 125 are disposed so as to be different from each other by about 90 degrees in the circumferential direction of the main body portion 123. The main body portion 123, the flange portion 121, and the connector portion 125 are integrally formed of an insulative polymer material (resin) having good moldability, for example, nylon (registered trademark). The connector 125 is a male connector having an opening 125h facing radially outward, and a mating connector (in this example, a female connector) of an external device can be inserted and removed in the radial direction through the opening 125h. ing.

One flange hole 121h is opened in the flange portion 121, and a screw (not shown) inserted through the flange hole 121h is screwed into a screw hole provided in a body to be attached to the gas sensor 200 (for example, an intake system of an internal combustion engine). By doing so, the gas sensor 200 can be attached to an attachment object.
A concave groove 50b (see FIG. 2) is formed in the metal shell 50 along the circumferential direction, and a seal member (O-ring) 90 is externally fitted in the concave groove 50b. Therefore, when the gas sensor 200 is inserted and attached to the opening of the object to be attached of the gas sensor from the front end side, the seal member 90 is crushed by the wall surface of the object to be attached, and the space between the object to be attached and the gas sensor 200 (the metal shell 50). It is designed to seal.
On the other hand, as will be described in detail later, the base portion 120 is insert-molded on the rear end side of the cylindrical body 110, and the front end side of the cylindrical body 110 is exposed from the base portion 120 to form an exposed portion 110n. The exposed portion 110n is connected to the rear end side of the metal shell 50, thereby separating the base body 120 and the metal shell 50.

Next, each component of the gas sensor 200 will be described in more detail with reference to FIG.
The gas sensor element 10 has a generally prismatic shape extending in the direction of the axis O as is well known, and a detection element for detecting the oxygen concentration and a heater for heating to activate the detection element are bonded to each other. It is a laminate. The detection element has a configuration in which a solid electrolyte body mainly composed of zirconia and a pair of electrodes mainly composed of platinum are stacked via an insulating layer in which a hollow measurement chamber is partially formed. More specifically, the detection element exposes one of a pair of electrodes formed on both surfaces of the solid electrolyte body to the outside and an oxygen pump cell in which the other electrode is disposed in the measurement chamber, and both surfaces of the solid electrolyte body. One of the formed pair of electrodes is arranged in the measurement chamber, and the other electrode is arranged in the reference gas chamber, and the output voltage of the oxygen concentration measurement cell becomes a predetermined value. As described above, the current flowing between the pair of electrodes of the oxygen pump cell is controlled to draw out oxygen in the measurement chamber or pump oxygen into the measurement chamber from the outside.
Of the oxygen pump cell, a portion of the pair of electrodes and a solid electrolyte body sandwiched between these electrodes forms a detection unit 11 through which a current corresponding to the oxygen concentration flows. On the other hand, the rear end portion 12 of the gas sensor element 10 has five electrode pads 12a (two of which are the second ones of the gas sensor element 10 in FIG. 3) for taking out the output from the detection element and supplying power to the heater. It is arranged on the surface 10b side, and the remaining three are arranged on the first surface 10a). These electrode pads 12a are connected to connection terminals 30 and 31, respectively (see FIGS. 2 and 3).

A ceramic holder 21 made of an insulating ceramic (e.g., alumina) and formed in a substantially short cylindrical shape is slightly inserted from the center in the axial direction of the gas sensor element 10. It arrange | positions in the state which made the detection part 11 protrude to the front end side from self.
The gas sensor element 10 is held by being surrounded by a cylindrical metal shell 50. The metal shell 50 is made of stainless steel such as SUS430. Specifically, a step portion 54 is formed on the inner periphery of the metal shell 50, and the front end side peripheral portion of the ceramic holder 21 through which the gas sensor element 10 is inserted is locked to the step portion 54. Further, a sealing material 22 is loaded on the inner periphery of the metal shell 50 from the rear end side of the ceramic holder 21 in a state where the sealing material 22 is inserted through the gas sensor element 10. A cylindrical sleeve 23 is fitted into the metal shell 50 so as to hold the sealing material 22 from the rear end side. An annular caulking packing 29 is disposed on the outer periphery on the rear end side of the sleeve 23.

On the other hand, a rear end portion 59 having a reduced diameter is formed on the outer peripheral rear end side of the metal shell 50, and a diameter-expanding portion 57 that expands in a step shape radially outward is formed at the tip of the rear end portion 59. ing. A groove 50b is formed in the enlarged diameter portion 57 along the circumferential direction, and a seal member (O-ring) 90 is fitted on the groove 50b. Further, a distal end engaging portion 56 that is smaller in diameter than the enlarged diameter portion 57 and that engages an outer protector 100 and an inner protector 102 described later is formed on the distal end side of the enlarged diameter portion 57. On the other hand, a caulking part 53 for caulking and holding the gas sensor element 10 in the metal shell 50 is formed on the rear end side of the rear end part 59.
The crimping portion 53 of the metal shell 50 is crimped so as to press the sleeve 23 toward the distal end side via the crimping packing 29. Due to the formation of the caulking portion 53, the sealing material 22 pressed through the sleeve 23 is crushed in the metal shell 50 and filled in details. With this sealing material 22, the ceramic holder 21 and the gas sensor element 10 are mainly used. It is positioned in the metal fitting 50 and is kept airtight.

  On the other hand, the outer peripheral surface of the detection unit 11 of the gas sensor element 10 is covered with a porous protective layer 15 to protect the electrode exposed to the outside of the detection unit 11 from poisoning due to intake air or the like. Then, the outer protector 100 and the inner protector 102 are fitted to the front end engaging portion 56 of the metal shell, and are fixed by laser welding to protect the detection unit 11 housed inside. A gas introduction hole 115 is formed in the outer protector 100, and a gas introduction hole 117 is formed in the inner protector 102. Therefore, it can suppress that the water | moisture content and oil component contained in gas adhere to the gas sensor element 10, and it can suppress that a crack and a crack arise in the gas sensor element 10. FIG. Moreover, it can suppress that the soot contained in gas adheres to the gas sensor element 10, and can suppress that the detection accuracy of the gas sensor 200 falls.

Next, the base body 120 and the cylindrical body 110 will be described.
The cylindrical body 110 has a cylindrical shape made of, for example, stainless steel whose rear end is enlarged in diameter (see FIG. 3), and this enlarged diameter portion forms a protruding portion 110p that protrudes radially outward. The base body part 120 is insert-molded on the rear end side of the cylindrical body 110 including the protruding part 110p, and the front end side of the cylindrical body 110 is exposed from the base body part 120 to form an exposed part 110n. Then, the front end side of the exposed portion 110n is externally fitted to the rear end portion 59 of the metal shell 50, and is connected by laser welding or the like, so that the base 120 is separated from the metal shell 50 in a state separated from the metal shell 50. It is fixed. The base 120 is a cover that surrounds the rear end 12 side of the gas sensor element 10 that protrudes toward the rear end of the metal shell 50.
Further, a connector terminal 60 that is electrically connected to an external device is held inside the connector part 125, and the connector part 125 is insert-molded to the connector terminal 60.

Further, as shown in FIG. 3A, a substantially bowl-shaped separator 127 that extends toward the tip is integrally formed in the main body 123. On the other hand, each of the connection terminals 30 and 31 is bent into a U-shape and is in contact with the corresponding electrode pad 12a (see FIG. 2), and from the bent end portions 30a and 31a to the rear end side. The bases 30e and 31e, which are folded back and have a substantially rectangular box shape in cross section, are provided. Note that the three connection terminals (the right side in FIG. 3) take out the output from the detection element, and the two connection terminals (the left side in FIG. 3) supply power to the heater.
Then, as shown in FIG. 3B, the base portions 30e of the connection terminals 30 are fitted into the four rectangular holes 127h partitioned by the separator portion 127, and similarly partitioned by the separator portion 127. The connection terminals 30 and 31 are held by the separator 127 by inserting and fitting the base 31 e of the connection terminal 31 into one rectangular hole 127 h 2. When the rear end portion 12 of the gas sensor element 10 is inserted into the central opening of the separator portion 127, the connection terminals 30 and 31 are electrically connected to the electrode pad 12a so as to surround the corresponding electrode pad 12a.
When the connection terminal 31 is inserted into the hole 127h2, the spring piece 31f provided inside the base 31e is electrically connected to the end 60a of the corresponding connector terminal 60 (FIG. 2). reference). The same spring piece is electrically connected to the end 60a of the corresponding connector terminal 60 for the connection terminal 30 (not shown). In this way, the gas sensor element 10 inside the gas sensor 200 and the external device can be electrically connected.

As described above, the base metal part 50 is integrated with the metal cylinder 110 by insert molding or the like, and the metal shell 50 and the base part 120 are connected via the cylinder 110, whereby the metal shell 50 and the base part are connected. The base 120 can be easily attached to the rear end side of the metal shell 50 without providing a complicated structure in 120, and productivity can be improved.
Further, by integrating the base portion 120 with the cylindrical body 110 by insert molding or the like, the number of parts can be reduced, the cost can be reduced, and the productivity can be further improved. If the number of parts is reduced, the weight can be reduced. When the weight of the gas sensor is reduced, the vibration of the part to which the gas sensor is attached can be reduced, and the vibration resistance of the gas sensor and the attachment part can be improved.
Further, for example, in order to connect the metal shell 50 and the base body portion 120, a flange is provided in the base metal portion 120, and the metal shell 50 is provided with a caulking portion for caulking and fixing the flange. It is possible to reduce the size of the gas sensor.
Furthermore, by disposing the metal shell 50 and the base body portion 120 apart from each other via the cylindrical body 110, it is possible to suppress the heat of the metal shell 50 from being directly transmitted to the base body portion 120 and causing the thermal deterioration of the base body portion 120. .

In the present embodiment, the exposed portion 110n of the cylindrical body 110 exposed from the base portion 120 to the front end side is formed straight (extends parallel to the axial direction). For this reason, after integrating the base portion 120 into the cylindrical body 110 by insert molding or the like, the cylindrical body 110 (the exposed portion 110n thereof) can be easily removed from the mold. On the other hand, if the exposed portion 110n is not formed straight, an expensive and complicated device such as a slide mold is required to remove the cylindrical body 110 after molding, which increases the manufacturing cost.
Furthermore, in the present embodiment, since the protruding portion 110p that protrudes in the radial direction is provided at a portion of the cylindrical body 110 where the base portion 120 is integrated by insert molding or the like, the cylindrical body 110 is separated from the base portion 120. Dropping in the direction of the axis O can be suppressed.

Furthermore, in this embodiment, the connector part 125 is provided in the base | substrate part 120, and the connector part 125 is integrated by the insert molding etc. in the connector terminal 60 provided in this connector part 125 inside. This eliminates the need for a separate part for holding the connector terminal 60 on the base 120, further reducing the number of parts, further reducing the cost, and simultaneously connecting the cylindrical body 110 and the connector terminal 60 when the base 120 is manufactured. Since it can fix, productivity can be improved further.
Furthermore, in this embodiment, the separator part 127 is integrally provided on the base part 120. This eliminates the need for a separator as a separate part for holding the connection terminals 30 and 31, and a separate member (for example, a metal cylindrical holding bracket) for attaching the separator to the base 120, further reducing the number of parts, The cost can be further reduced and the productivity can be further improved.
Since the connection terminals 30 and 31 have a complicated shape, it is difficult to integrate the base portion 120 around the connection terminals 30 and 31 by insert molding or the like. Therefore, the connection terminals 30 and 31 can be easily assembled by being fitted to the separator portion 127.

It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.
For example, the protruding portion of the cylindrical body only has to protrude in the radial direction. In addition to the case where the rear end side is enlarged in diameter as shown in FIG. The diameter may be increased. Furthermore, as shown in FIG. 4, the cylindrical body 111 has a cylindrical shape with the same diameter as a whole, and only a part of the portion where the base portion 120 is integrated by insert molding or the like is protruded in the radial direction to protrude the protruding portion 111 p. In this case as well, the tip side of the protruding portion 111p of the cylindrical body 111 is exposed from the base portion 120 to form an exposed portion 111n. The protrusions may protrude radially inward, and the number of protrusions is not limited to one, and a plurality of protrusions may be provided in the direction of the axis O.

Further, as shown in FIG. 5, a seal member 92 may be provided inside the base portion 120 (main body portion 123) of the gas sensor 210 so as to be in contact with the side surface of the cylindrical body 112. The gas sensor 210 is the same as the gas sensor 200 of FIG. 1 except that the gas sensor 210 includes the seal member 92 and the main body 123 is provided with a receiving groove 123h and the shape of the cylindrical body 112 is different. Constituent parts are denoted by the same reference numerals and description thereof is omitted.
In FIG. 5, the cylindrical body 112 does not have a protruding portion that protrudes radially outward, and has a straight cylindrical shape parallel to the axis O direction. The main body portion 123 is provided with an annular housing groove 123h that opens toward the rear end side while the front end is open and that faces the front end portion 112s on the outer surface of the cylindrical body 112. The seal member 92 is housed in the housing groove 123h, and the inner surface of the seal member 92 is in contact with the distal end portion 112s of the outer surface of the cylindrical body 112.

Usually, the base portion 120 (main body portion 123) made of a polymer material and the metal cylinder 112 ensure airtightness at the close contact surfaces by integration such as insert molding. When exposed to a high temperature, the base portion 120 having a high coefficient of thermal expansion may expand more and a gap may be formed between the cylindrical body 112 and the base body portion 120.
Therefore, by providing the sealing member 92 inside the base portion 120 (main body portion 123) so as to be in contact with the side surface 112s of the cylindrical body 112, even if the gas sensor 210 is exposed to high temperature, The sealing member 92 seals the gap between them, and airtightness can be secured. A rubber O-ring can be used as the seal member 92. In particular, it is preferable that the thermal expansion coefficient of the seal member 92 is larger than that of the base portion 120 (main body portion 123), because the seal becomes more reliable.

In the example of FIG. 5, an O-ring having a trapezoidal cross section is used as the seal member 92 and is accommodated in the accommodation groove 123h with the upper base side facing the rear end side. The O-ring having a trapezoidal cross section is more closely attached to the inside of the receiving groove 123h than the O-ring having a circular cross section, and thus is less likely to drop out of the receiving groove 123h when the gas sensor 210 is transported. The tip of the seal member 92 is substantially flush with the tip-facing surface of the main body 123, and after the gas sensor 210 is attached to the attachment target body, the tip-facing surface of the main body 123 becomes the attachment surface and seals. Since it contacts the tip side of the member 92, the seal member 92 does not fall off.
Note that the side surface of the cylindrical body 112 in contact with the seal member 92 is not limited to the outer surface, and may be an inner surface. In addition, since the base portion is integrated with the rear end side of the cylindrical body by insert molding or the like, the portion for accommodating the seal member 92 (accommodating groove 123h in the example of FIG. 5) needs to be an internal space whose tip is open. There is.

By the way, when the gas sensor is transported or the like, there is a possibility that the seal member 92 contracts and falls out of the housing groove 123h. In order to prevent this, if the seal member 92 is excessively compressed and stored in the storage groove 123h, the seal member 92 may sag due to a creeping phenomenon with time, and the sealing performance may be deteriorated.
Therefore, as shown in FIG. 6, the housing groove 123h2 of the gas sensor 220 is made deeper toward the rear end side than in the case of FIG. 5 (housing groove 123h), and after the seal member 92 is housed to the back of the housing groove 123h2, The housing groove 123h2 may be closed with the lid portion 123L on the tip side of the seal member 92. The lid 123L may also be formed from a polymer material.
For example, as shown in FIG. 6, an engagement protrusion 123p that protrudes radially outward and narrows toward the rear end side is formed on the outer surface of the lid portion 123L, and the engagement protrusion 123p is accommodated in the receiving groove. By engaging the recess formed on the outer surface of 123h2, the lid portion 123L can be prevented from falling off. Moreover, you may press-fit the cover part 123L in the accommodation groove 123h2.

  In the above embodiment, the sensor element has a rectangular plate shape with a rectangular cross section. However, the sensor element used in the gas sensor of the present invention may have a square cross section. Other than that. Furthermore, in the above description, the full-range air-fuel ratio gas sensor is embodied, but the gas sensor according to the present invention can be embodied in other gas sensors.

DESCRIPTION OF SYMBOLS 10 Gas sensor element 11 Detection part 12 Rear end part 30 and 31 of gas sensor element 50 Metal terminal 60 Connector terminal 92 Seal member 110, 111, 112 Cylindrical body 112s Side surface of cylindrical body 110n, 111n Exposed part 110p, 111p Protruding part 120 Base part 123h, 123h2 Housing groove 123L Lid part 125 Connector part 127 Separator part 200, 210, 220 Gas sensor O Axis

Claims (9)

A gas sensor element that extends in the axial direction and has a detection unit for detecting a specific gas component in the gas to be measured on its tip side;
A metal shell surrounding the gas sensor element in the radial direction and holding the gas sensor element;
A base portion made of a polymer material, which is disposed on the rear end side of the metal shell and covers the rear end side of the gas sensor element;
A gas sensor comprising:
A metal cylinder connecting the metal shell and the base part, the base part being integrated on the rear end side of the metal shell, and the tip side of the base part being exposed from the base part to form an exposed part Further equipped with a body,
A gas sensor in which a part of the exposed portion of the cylindrical body is connected to the metal shell, and the base portion is disposed apart from the metal shell.   The gas sensor according to claim 1, wherein the exposed portion of the cylindrical body extends parallel to the axial direction.   The gas sensor according to claim 1, wherein the rear end portion of the cylindrical body has a protruding portion that protrudes in a radial direction inside the base body portion. The base portion has a connector portion that is stretched in a direction intersecting the axial direction and can be removed from an external device;
The gas sensor according to any one of claims 1 to 3, wherein the connector portion includes a connector terminal that is electrically connected to the external device, and the connector portion is integrated with the connector terminal.   The gas sensor as described in any one of Claims 1-4 which has a sealing member arrange | positioned inside the said base | substrate part so that the side surface of the said cylinder may be contact | connected. The base portion has an accommodation groove that extends toward the rear end side with the front end open and that faces at least a part of the side surface of the cylindrical body, and the seal member is accommodated in the accommodation groove,
The gas sensor according to claim 5, further comprising a lid portion that closes the housing groove on a tip side of the seal member. A connection terminal electrically connected to the gas sensor element;
The gas sensor according to claim 1, wherein the base portion integrally includes a separator portion that holds the connection terminal.   The gas sensor according to claim 7, wherein the connection terminal is fitted into the separator portion. A gas sensor element that extends in the axial direction and has a detection unit for detecting a specific gas component in the gas to be measured on its tip side;
A metal shell surrounding the gas sensor element in the radial direction and holding the gas sensor element;
A base portion made of a polymer material, which is disposed on the rear end side of the metal shell and covers the rear end side of the gas sensor element;
A method of manufacturing a gas sensor comprising:
It is a metal cylinder, and the base body part is insert-molded on its rear end side, and its front end side is exposed from the base body part to form an exposed part,
A method of manufacturing a gas sensor, wherein a part of the exposed portion of the cylindrical body is connected to the metal shell so that the base portion is separated from the metal shell.

Images