WO2017183229A1

WO2017183229A1 - Gas sensor

Info

Publication number: WO2017183229A1
Application number: PCT/JP2016/085769
Authority: WO
Inventors: 邦彦米津; 健弘大場
Original assignee: 日本特殊陶業株式会社
Priority date: 2016-04-20
Filing date: 2016-12-01
Publication date: 2017-10-26
Also published as: JP2017194330A

Abstract

The purpose of the present invention is to provide a gas sensor that has a base part and flange part made from a polymer material and can be made to be smaller. Provided is a gas sensor 200 provided with: a gas sensor element 10 having a detection unit 11; a main metal fitting 50 for holding the gas sensor element; a base part 120 that is made from a polymer material, and is connected to the rear-end side of the main metal fitting directly or via another member 110 and covers the rear-end side of the gas sensor element; a flange part 121 that integrally extends from the base part in the radial direction and is provided with an attachment hole 121h for attachment to an object to be attached to 300; and a cylindrical metallic collar 80 that is fixed to the attachment hole and in which a connection member 310 for connecting to the object to be attached is inserted. The leading-end-facing surface 80a of the collar protrudes further toward the leading end side than the leading-end-facing surface 121a of the flange part.

Description

Gas sensor

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

A gas sensor is attached to an intake system (for example, an intake pipe or an intake manifold) of an internal combustion engine such as a diesel engine or a gasoline engine, and the concentration of a specific gas is monitored to control a combustion state or the like. Conventionally, in this gas sensor, a male screw portion provided outside a case (main metal fitting) that accommodates a gas detection element is screwed to a female screw portion that is formed in a wall surface of an intake pipe.
By the way, when a vehicle equipped with an internal combustion engine collides, it is necessary to secure a gap between the bonnet and the engine parts in order to reduce the impact on the collision target. Therefore, it is necessary to shorten the protruding length of the gas sensor to the outside of the intake pipe.
Therefore, while holding the gas sensor element with a metal metal shell, a gas sensor that has a protruding length of the gas sensor shortened by joining a resin cover to the rear end side of the metal shell and housing the terminal metal fitting in the cover. Known (Patent Document 1). In this gas sensor, a pair of flange portions extend in the radial direction from the cover, and attachment holes are provided in the flange portions, and a metal cylindrical collar is integrally attached to the attachment holes by insert molding or the like. A screw is inserted into the collar, and a gas sensor is screwed into the intake pipe.

Japanese Patent Laying-Open No. 2011-145267 (FIG. 2)

Incidentally, as shown in FIG. 6, in the gas sensor described in Patent Document 1, the front end facing surface (mounting surface) 620 s of the flange portion 620 is fixed so as to contact the outer surface 300 s of the intake pipe (mounting object) 300. . Further, the flange portion 620 is pressed to the tip side by the pressing force F of the screw 310. When the ambient temperature becomes high while the pressing force F of the screw 310 is acting, the resin flange 620 tends to extend toward the tip end in the axial direction of the arrow H due to thermal expansion. However, since the flange portion 620 is pressed to the front end side by the pressing force F of the screw 310 and is in close contact with the outer surface 300s, the flange portion 620 cannot extend in the direction of the arrow H and is compressed in the opposite direction (the rear end side in the axial direction). The stress C acts on the flange portion 620. For this reason, in order to secure the strength that can withstand the compressive stress C, it is necessary to increase the radial dimension dx between the collar 800 and the flange portion 620, and there is a problem that the gas sensor is increased in size.
Accordingly, an object of the present invention is to provide a gas sensor that has a base portion and a flange portion made of a polymer material and can be miniaturized.

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 metal shell surrounding the periphery and holding the gas sensor element; and a base portion made of a polymer material connected to the rear end side of the metal shell directly or via another member to cover the rear end side of the gas sensor element; A flange portion that extends integrally from the base portion in the radial direction and has a mounting hole for mounting on the mounting target body, and a connecting member that is fixed to the mounting hole and connected to the mounting target body is inserted therethrough A gas sensor comprising: a metal cylinder-shaped collar, wherein a front-facing surface of the collar protrudes further to a front-end side than a front-facing surface of the flange portion.

According to this gas sensor, when the connecting member is inserted into the collar and the gas sensor is attached to the attachment target body, the tip-facing surface of the collar is in contact with the outer surface of the attachment target body, and between the tip-facing surface and the outer surface of the flange portion. A gap is created. Even if the flange portion is pressed against the distal end side by the pressing force of the connecting member, the flange portion is not restrained by the outer surface and is in a free state. Therefore, when the ambient temperature becomes high, the flange portion made of the polymer material can be extended in the axial direction by thermal expansion without receiving a restraining force, and the generation of compressive stress can be suppressed. For this reason, it is not necessary to secure the strength enough to withstand the compressive stress, the radial dimension between the collar and the flange portion can be reduced, and the gas sensor can be downsized.

When the inner diameter of the collar is r (mm) and the shortest distance between the outer surface of the collar and the outer peripheral edge of the flange portion is d (mm), it is preferable that d ≦ r / 2 is satisfied.
According to this gas sensor, the radial dimension between the collar and the flange portion can be further reduced, and further downsizing of the gas sensor can be realized.

A concave portion or a through hole is formed on the outer surface of the collar, and the polymer material constituting the base portion may enter the concave portion or the through hole.
According to this gas sensor, since the collar and the flange portion can be firmly fixed, even if the flange portion extends in the axial direction due to thermal expansion, separation of the collar and the flange portion can be suppressed.

According to this invention, a gas sensor having a base portion and a flange portion made of a polymer material can be reduced in size.

It is a perspective view which shows the structure of the gas sensor which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. It is a top view which shows the structure of a gas sensor. It is a figure which shows the state which attached the gas sensor to the attachment target body. It is the elements on larger scale of FIG. It is a figure which shows the state which attached the conventional gas sensor to the attachment target body.

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 line AA of FIG. 1, FIG. 3 is a top view of the gas sensor 200, and FIG. FIG. FIG. 1 is a bottom view of the gas sensor 200 as viewed from the front end side.
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 convenience, only three

connection terminals

30 and 31 are displayed and only one connector terminal 60 is displayed. However, in actuality, the

connection terminals

30 and 31 and the connector terminal 60 are There are provided a plurality (in the embodiment of the present invention, 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, PPS (polyethylene sulfide). 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 mounting hole 121h is opened in the flange 121, and a metal cylindrical collar 80 is insert-molded in contact with the inner surface of the mounting hole 121h and fixed integrally (see FIG. 3). The collar 80 is made of a metal material, for example, stainless steel such as SUS304L. Then, as shown in FIG. 4, the screw 310 is inserted into the collar 80, and the screw 310 is screwed into a screw hole provided in the attachment target body 300 (for example, an intake system of the internal combustion engine), whereby the gas sensor 200 is configured. It can be attached to the attachment object 300.
The screw 310 corresponds to a “connecting member” in the claims.
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, as shown in FIG. 4, when the gas sensor 200 is inserted and attached to the opening 300 h of the attachment target body 300 from the distal end side, the seal member 90 is crushed by the wall surface of the opening 300 h of the attachment target body 300, The space between the gas sensor 300 and the gas sensor 200 (the metal shell 50) is sealed.

On the other hand, the base body part 120 is insert-molded and integrated on the rear end side of the cylindrical body 110. The cylindrical body 110 corresponds to an “other member” in the claims. The base body 120 may be directly connected (integrated) to the rear end side of the metal shell 50 by insert molding or the like without providing the cylindrical body 110.
Further, the front end facing surface 121a of the flange portion 121 is flush. Here, the tip-facing surface of the flange portion 121 is a portion radially outward from the maximum outer diameter of the metal shell 50 (in the case of having the cylinder 110, the maximum outer diameter of the metal shell 50 and the cylinder 110). Say. This part faces the surface of the attachment object 300 (attachment surface 300s).
Further, a plurality of gas introduction holes 115 are provided on the side surface of the outer protector 100, and one gas discharge hole 116 is provided at the center of the tip of the outer protector 100.

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.

In the oxygen pump cell, the pair of electrodes and the portion of the solid electrolyte body that is sandwiched between these electrodes constitute the 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 of the gas sensor element 10 in FIG. 2) 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.

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 portion 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 portion 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, and the ceramic holder 21 and the gas sensor element 10 are mainly formed by the sealing material 22. 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 or water exposure 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. In addition, one gas discharge hole 116 is provided at the center of the front end of the outer protector 100.

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 side expands through a stepped portion, and a base portion 120 is insert-molded on the rear end side of the cylindrical body 110 including the stepped portion. The part 120 is prevented from coming off the cylinder 110.
Then, the base body 120 is fixed to the metal shell 50 by fitting the front end side of the cylindrical body 110 exposed from the base body 120 to the rear end portion 59 of the metal shell 50 and connecting it by laser welding or the like.
The base 120 is a cover that surrounds the rear end 12 side of the gas sensor element 10 projecting toward the rear end of the metal shell 50. Furthermore, a connector terminal 60 that is electrically connected to an external device is held inside the connector portion 125. The connector part 125 including the connector terminal 60 is formed by insert molding.
Further, a substantially bowl-shaped separator portion 127 extending toward the tip is integrally formed inside the main body portion 123 and holds the

connection terminals

30 and 31. In addition,

spring pieces

30f and 31f are provided at one end of the

connection terminals

30 and 31, and are electrically connected to the end portion 60a of the corresponding connector terminal 60. In this way, the gas sensor element 10 inside the gas sensor 200 and the external device are electrically connected.

Next, the flange portion 121 and the collar 80 will be described with reference to FIG. FIG. 5 is a partially enlarged view of FIG.
As shown in FIG. 5, in the present embodiment, the tip-facing surface 80 a of the collar 80 protrudes further to the tip side than the tip-facing surface 121 a of the flange portion 121. For this reason, when the screw 310 is inserted into the collar 80 and screwed into the screw hole of the attachment target body 300, the tip-facing surface 80a of the collar 80 contacts the outer surface 300s of the attachment target body 300, and the tip-facing surface 121a of the flange portion 121. And a gap G between the outer surface 300s and the outer surface 300s.
Even if the flange portion 121 is pressed to the front end side through the collar 80 by the pressing force F of the screw 310, the flange portion 121 does not adhere to the outer surface 300s and is not restrained by the outer surface 300s. It becomes. Therefore, when the ambient temperature becomes high, the flange portion 121 made of a polymer material can be extended in the axial direction of the arrow H by thermal expansion without receiving a restraining force, and the object to be attached due to the thermal expansion of the flange portion 121. It can suppress that the compressive stress received from the outer surface 300s of the body 300 arises in the flange part 121. FIG. For this reason, it is not necessary to ensure sufficient strength to withstand compressive stress, the radial dimension d1 between the collar 80 and the flange portion 121 can be reduced, and the gas sensor can be downsized.

In particular, as shown in FIG. 3, when the inner diameter of the collar 80 is r (mm) and the shortest distance between the outer surface of the collar 80 and the outer peripheral edge of the flange portion 121 is d (mm), d ≦ r / 2 is satisfied. If it is satisfied, the dimension d1 can be further reduced, and further downsizing of the gas sensor can be realized.
When the cross-sectional shape of the through hole of the collar is not a perfect circle, the inscribed circle inscribed in the through hole is set as the inner diameter of the collar.

The tip-facing surface 80a of the collar 80 is preferably protruded by about 0.1 to 0.2 mm from the tip-facing surface 121a of the flange portion 121.
Further, the rear end facing surface of the collar 80 also protrudes rearward from the rear end facing surface of the flange portion 121. This is because the screw 310 is not brought into contact with the metal collar 80. This is because the screw 310 is inserted into the resin flange portion 121 by the pressing force F.

A recess is formed on the outer surface of the collar 80, and the recess is preferably filled with a polymer material constituting the flange portion 121.
Thereby, it can suppress that the collar 80 and the flange part 121 isolate | separate. Instead of the recess, a through hole penetrating from the outer surface of the collar to the inner surface may be formed.

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 number of the flange portions 121 is not limited to one, and one flange portion 121 may be provided on each side of the base portion 120.
Further, the connection between the base body 120 (main body 123) and the metal shell 50 or another member (cylinder 110) is not limited to insert molding.
The connecting member is not limited to a screw, and may be a bolt, a rivet or the like, for example.
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 50 Main metal fitting 80 Color 80a Color front-facing surface 110 Other members (cylinder)
120 Base part 121 Flange part 121a Front-facing surface of flange part 121h Attachment hole 200 Gas sensor 300 Attachment object 310 Connection member (screw)
O axis r inner diameter of collar d shortest distance between outer surface of collar and outer periphery of flange

Claims

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 part made of a polymer material, which is connected to the rear end side of the metal shell directly or via another member and covers the rear end side of the gas sensor element;
A flange portion provided with an attachment hole for extending integrally from the base portion in the radial direction and being attached to an attachment object;
A metal cylindrical collar that is fixed to the attachment hole and through which a connection member for connection to the attachment object is inserted,
A gas sensor comprising:
The gas sensor according to claim 1, wherein the tip-facing surface of the collar protrudes further to the tip side than the tip-facing surface of the flange portion.
2. The gas sensor according to claim 1, wherein the inner diameter of the collar is r (mm) and the shortest distance between the outer surface of the collar and the outer peripheral edge of the flange portion is d (mm), and d ≦ r / 2 is satisfied.
The gas sensor according to claim 1 or 2, wherein a concave portion or a through hole is formed on an outer surface of the collar, and the polymer material constituting the base portion enters the concave portion or the through hole.