JP6899309B2 - Sensor - Google Patents

Description

The present invention relates to a sensor in which a detection element is held inside an outer cylinder and the rear end side of the outer cylinder is closed with an elastic member.

Conventionally, a gas sensor using a solid electrolyte made of ceramics such as zirconia and having a detecting element for detecting the concentration of a specific gas component (for example, oxygen) in the exhaust gas discharged from an internal combustion engine has been known. For example, in the detection element of the oxygen sensor that detects the oxygen concentration, the detection electrode exposed to the exhaust gas and the reference electrode exposed to the reference gas (usually the atmosphere) are paired to sandwich the solid electrolyte body. It is formed on its surface. This detection element detects the oxygen concentration in the exhaust gas according to the difference in oxygen partial pressure between the two atmospheres separated by the solid electrolyte body, that is, between the exhaust gas and the reference gas.

Such an oxygen sensor has a main metal fitting for holding the detection element and a metal outer cylinder such as stainless steel that covers the periphery of the detection element, and further, the outer cylinder is on the rear end side of the outer cylinder. A plug member (grommet) for closing the inside of the cylinder is assembled. The plug member is provided with a lead wire insertion hole through which a lead wire (sensor output lead wire and heater lead wire) is inserted (Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-215095

By the way, as shown in FIG. 6, the outer cylinder 1002 and the grommet 1004 are crimped inward in the radial direction by a round crimping die 1100 or the like at one place in the axial direction, and are fixed to each other by the crimping portion 1002s.
However, due to the crimping, the rear end portion 1002e of the outer cylinder 1002 may be pulled by the crimping portion 1002s to increase the diameter, and a gap G may be generated between the rear end portion 1002e and the grommet 1004. Then, when the gap G becomes large, the antifreeze agent (calcium chloride particles) in winter falls into the gap G and the inside of the outer cylinder 1002, and further water is applied to dissolve components such as calcium chloride, and the vicinity of the gap G and the vicinity of the gap G Further, there is a risk of causing gap corrosion of the outer cylinder 1002 at the inner part.
Therefore, an object of the present invention is to provide a sensor that reduces the gap between the outer cylinder and the elastic member due to crimping and suppresses the gap corrosion of the outer cylinder.

In order to solve the above problems, the sensor of the present invention extends in the axial direction and has a detection element having a detection unit on its tip side and a detection element protruding from its tip in the radial direction of the detection element. A main metal fitting that surrounds the periphery, a metal tubular outer cylinder that is arranged on the rear end side of the main metal fitting, and an elastic member that is arranged inside the outer cylinder and closes the rear end side of the outer cylinder. The outer cylinder has a first crimping portion formed by being crimped inward in the radial direction together with the elastic member, and the elastic member is a rear end of the first crimping portion. The outer cylinder has a convex portion that protrudes radially outward from the first crimping portion on the side, and the outer cylinder has a diameter larger than that of the first crimping portion at a position that further overlaps the convex portion in the radial direction. have a 2 caulking portion, the second caulking portion, said a convex portion and a non-contact, and is a diameter larger than the inner diameter of the rear end edge of the outer cylinder the inner diameter of said first caulked portion It is characterized by that.

The first crimping portion has a function of reducing the diameter of the elastic member inward in the radial direction to form a convex portion and fixing the elastic member to the outer cylinder, but the rear end side of the outer cylinder is pulled to the first crimping portion. There is a possibility that the diameter will be increased and a large gap will be created between the rear end of the outer cylinder and the elastic member.
Therefore, according to this sensor, the diameter of the rear end side of the outer cylinder is expanded by forming the second crimping portion on the rear end side of the first crimping portion at a position where it overlaps the convex portion in the radial direction. The generated gap can be reduced or suppressed, and the gap corrosion of the outer cylinder can be suppressed. Since the second crimping portion may suppress or correct the diameter expansion of the outer cylinder, it does not have to be crimped more strongly than the first crimping portion, and the diameter is larger than that of the first crimping portion.
Further, since the rear end side of the outer cylinder is crimped by the second crimping portion having a diameter larger than that of the first crimping portion (in other words, the crimping is weak), the rear end side of the outer cylinder is first crimped. It is possible to prevent the outer cylinder from being distorted toward the rear end edge of the outer cylinder and wrinkles from being generated in the outer cylinder as compared with the case where the outer cylinder is strongly crimped as in the tightening portion.
Further, since the degree of crimping of the second crimping portion is further small, distortion and wrinkles of the outer cylinder due to crimping can be further suppressed.

In the sensor of the present invention, the elastic member is provided with a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness. The atmospheric communication holes that enable atmospheric communication between the inside and the outside of the cylinder are formed so as to extend in the axial direction, respectively, and the elastic member starts from the atmospheric communication holes on its own rear end facing surface side. The elastic member extends outward in the radial direction while avoiding the lead wire insertion hole, has a groove portion having a bottom surface and a side surface, and has a notch toward the tip end side of the elastic member, and the elastic member from the rear end side in the axial direction. A protective portion that protects the filter member by covering the atmospheric communication hole and has an opening smaller than the opening of the atmospheric communication hole, and a protective portion that is connected to the protective portion and extends in the radial direction at least. An arm portion, part of which is arranged in the groove portion of the elastic member, may be connected to the outer cylinder, and the arm portion may be arranged with a gap from the bottom surface of the groove portion.
Since the arm on the rear end side of the outer cylinder is thin, its strength is lower than other parts. Therefore, by forming a second crimping portion having a diameter larger than that of the first crimping portion at a position on the rear end side of the first crimping portion and overlapping the convex portion in the radial direction, the outer cylinder may be distorted. It is possible to suppress the occurrence of wrinkles, and it is possible to suppress problems such as the arm being bent and interfering with the groove and the arm being damaged.

According to the present invention, the gap between the outer cylinder of the sensor and the elastic member due to crimping can be reduced, and the gap corrosion of the outer cylinder can be suppressed.

It is sectional drawing which cut the gas sensor which concerns on embodiment of this invention in the plane along the axial direction. It is a perspective view of the elastic member before assembling. It is a figure which looked at the gas sensor from the rear end side (upper side in FIG. 1) in the axial direction. It is a perspective view of the outer cylinder before assembling. It is sectional drawing which shows an example of the method of forming the 1st crimping part and the 2nd crimping part. It is sectional drawing which shows the conventional method of crimping an outer cylinder and a grommet.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view of the sensor (gas sensor) 1 according to the embodiment of the present invention cut along a plane along the axis O direction (direction from the front end to the rear end), and FIG. 2 is a perspective view of an elastic member before assembly. FIG. 3 is a view of the gas sensor from the rear end side in the axial direction (upper side in FIG. 1), and FIG. 4 is a perspective view of the outer cylinder before assembly.
The gas sensor 1 shown in FIG. 1 is used by being attached to an exhaust pipe (not shown) of exhaust gas discharged from an engine of an internal combustion engine such as an automobile. In the following, in the axis O direction of the gas sensor 1, the side toward the tip of the detection element 6 inserted into the exhaust pipe (closed side and lower side in the figure) is set as the tip side, and the side facing in the opposite direction (closed side and lower side in the figure). The upper side in the figure) will be described as the rear end side.

The gas sensor 1 shown in FIG. 1 is a sensor for detecting the concentration of oxygen in the exhaust gas flowing in the exhaust pipe, and the elongated and closed tubular detection element 6 is used as the main metal fitting 5 and the outer cylinder 3. , Has a structure held in the protector 4. A lead wire 18 for taking out a signal output from the detection element 6 and energizing a heater 7 attached to the detection element 6 is drawn from the gas sensor 1. Each lead wire 18 is electrically connected to a sensor control device (not shown) or an electronic control unit (ECU) of an automobile provided at a position away from the gas sensor 1.

The detection element 6 of the gas sensor 1 is formed by forming a solid electrolyte body 61 made of zirconia in a bottomed tubular shape, and a reference electrode 62 made of Pt or a Pt alloy covers almost the entire surface of the inner surface of the solid electrolyte body 61. It is formed in a porous shape so as to cover it. Further, a detection electrode 63 made of Pt or a Pt alloy is also formed on the outer surface of the solid electrolyte body 61 as in the reference electrode 62.
The tip end side (closed side) of the detection element 6 is configured as a detection unit 64, and the detection electrode 63 on the outer surface is exposed to the exhaust gas flowing in the exhaust pipe (not shown). Although not shown, the detection electrode 63 is covered with a porous electrode protective layer made of heat-resistant ceramics, and is protected from poisoning by exhaust gas. Further, a flange-shaped flange portion 65 projecting outward in the radial direction is provided at a substantially intermediate position in the axial direction O direction of the detection element 6.
A rod-shaped heater 7 for heating and activating the solid electrolyte body 61 is inserted in the tubular hole of the detection element 6.

The detection element 6 is held in the tubular hole 55 of the main metal fitting 5 in a state where its radial circumference is surrounded by the tubular main metal fitting 5. The main metal fitting 5 is a tubular member made of stainless steel such as SUS430, and a male screw portion 52 screwed into an exhaust pipe mounting portion (not shown) is formed on the tip side thereof. On the tip side of the male screw portion 52, a tip engaging portion 56 to which a protector 4 described later is engaged is formed on the outer periphery thereof. The detection unit 64 of the detection element 6 projects toward the tip end side of the tip engagement portion 56.

A tool engaging portion 53 whose diameter is expanded in the radial direction is formed on the rear end side of the male screw portion 52 of the main metal fitting 5, and is used when the gas sensor 1 is attached to the attachment portion (not shown) of the exhaust pipe. The mounting tool is engaged. An annular gasket 11 for preventing gas from escaping through the mounting portion of the exhaust pipe is fitted in the portion between the tool engaging portion 53 and the male screw portion 52.
A crimping portion 57 for crimping and fixing the detection element 6 held in the cylinder hole 55 is provided on the rear end side of the main metal fitting 5. The rear end portion 66 of the detection element 6 projects toward the rear end side of the crimping portion 57. Then, between the tool engaging portion 53 and the crimping portion 57, a rear end engaging portion 58 with which the tip portion 31 of the outer cylinder 3 described later is engaged is formed on the outer periphery thereof.

Next, a step portion 59 is provided on the tip end side of the main metal fitting 5 in the tubular hole 55 so that the inner circumference thereof protrudes inward in the radial direction, and a metal packing 12 is provided on the step portion 59. A tubular support member 13 made of alumina is locked therethrough. The inner circumference of the support member 13 is also formed in a stepped shape, and the flange portion 65 of the detection element 6 is supported by the support member 13 via a metal packing 14 arranged in the stepped portion. Further, the inside of the tubular hole 55 is filled with a filling member 15 made of talc powder on the rear end side of the support member 13, and the rear end side of the filling member 15 is sandwiched between the filling member 15 and the support member 13. A tubular sleeve 16 made of alumina is arranged on the surface.

An annular ring 17 is arranged on the rear end side of the sleeve 16, and by crimping the crimping portion 57 of the main metal fitting 5 inward in the radial direction, the sleeve 16 acts on the filling member 15 via the ring 17. It is pressed toward the tip side. Through the crimping of the crimping portion 57, the filling member 15 presses the flange portion 65 of the detection element 6 toward the support member 13 locked to the step portion 59 of the main fitting metal 5. When the inside of the tube 55 is compressed and filled, the gap between the inner peripheral surface of the tubular hole 55 and the outer peripheral surface of the detection element 6 is airtightly filled. In this way, the detection element 6 is held in the tubular hole 55 of the main metal fitting 5 via each member sandwiched between the crimping portion 57 and the step portion 59 of the main metal fitting 5.

Next, a protector 4 covering the detection portion 64 of the detection element 6 protruding from the tip engagement portion 56 toward the tip side in the axis O direction is assembled to the tip engagement portion 56 of the main metal fitting 5 by welding. ing. The protector 4 protects the detection unit 64 of the detection element 6 protruding into the exhaust pipe when the gas sensor 1 is attached to the exhaust pipe (not shown) from collision with water droplets, foreign substances, etc. contained in the exhaust gas. Is.
The protector 4 has a bottomed tubular shape, and has an outer protector 41 in which the peripheral edge on the open side is joined to the tip engaging portion 56 and a bottomed tubular inner protector fixed inside the outer protector 41. It is configured to form a double structure composed of 45. In the outer peripheral walls of the outer protector 41 and the inner protector 45, an introduction port 42 for introducing exhaust gas into the inside and guiding the exhaust gas to the detection unit 64 of the detection element 6 is opened (the gas introduction port of the inner protector 45 is Not shown.). Further, the bottom walls of the outer protector 41 and the inner protector 45 are opened with discharge ports 43 and 48 for discharging water droplets and exhaust gas that have entered the inside, respectively.

Further, a tubular separator 8 made of insulating ceramics is arranged on the rear end side in the axis O direction with respect to the rear end portion 66 of the detection element 6. The separator 8 has an accommodating portion 82 that independently accommodates four connection terminals 19 (three connection terminals 19 are shown in FIG. 1). The accommodating portion 82 penetrates the separator 8 in the O-axis direction, and is configured to be able to ventilate between the front end side and the rear end side of the separator 8. Each connection terminal 19 is a pair of electrodes 71 exposed on the rear end side for energizing the reference electrode 62, the detection electrode 63, and the heat generating resistor of the heater 7 (one of them in FIG. 1). The electrode 71 is shown), and each of them is electrically connected to the electrode 71.

The separator 8 accommodates each connection terminal 19 in a separated state, and prevents the connection terminals 19 from coming into contact with each other. The core wires of the four lead wires 18 are crimped and joined to each connection terminal 19 (two lead wires 18 are shown in FIG. 1), and each lead wire 18 is a grommet described later. It is pulled out to the outside of the gas sensor 1 via 9. Further, a flange portion 81 projecting outward in the radial direction is provided on the outer peripheral surface of the separator 8, and a substantially cylindrical holding metal fitting 85 is fitted on the outer peripheral surface on the tip end side of the flange portion 81. There is.

Further, a grommet 9 made of fluorinated rubber is arranged on the rear end side of the separator 8. As shown in FIG. 2, the grommet 9 is a member formed in a substantially columnar shape with the axis O direction as the height direction, and has an atmospheric communication hole 91 and four lead wire insertion holes 92 penetrating in the axis O direction. Have. The atmospheric communication holes 91 are formed in the radial center of the grommet 9, and the lead wire insertion holes 92 are positioned at equal intervals in the circumferential direction so as to surround the atmospheric communication holes 91 on the outer peripheral side of the atmospheric communication holes 91. It is formed in each.
As shown in FIG. 1, the air communication hole 91 is further provided to introduce the atmosphere into the gas sensor 1 (inside the outer cylinder 3 described later) via the accommodating portion 82 of the separator 8. Inside the outer cylinder 3, the detection element 6 is held by the main metal fitting 5 in a form in which the rear end portion 66 protrudes, and the reference electrode 62 formed in the bottomed cylinder of the detection element 6 is exposed to the atmosphere. It is configured to be exposed.
Then, as shown in FIG. 3, the four lead wires 18 described above are independently inserted into the four lead wire insertion holes 92. The grommet 9 corresponds to the "elastic member" in the claims.

Further, as shown in FIGS. 2 and 3, the rear end facing surface 99 facing the rear end side when the grommet 9 is assembled to the gas sensor 1 starts from the formation position of the atmospheric communication hole 91 and moves toward the outer peripheral side. Four groove portions 93 extending in a groove shape along the radial direction are formed. The groove 93 is notched toward the tip end side of the grommet 9, and is formed by two side surfaces 95 connecting the bottom surface 94 and the bottom surface 94 and the rear end facing surface 99. Each groove 93 is arranged through two adjacent lead wire insertion holes 92 so as to avoid the positions of the four lead wire insertion holes 92 that open on the rear end facing surface 99. Therefore, the rear end facing surface 99 is divided into four sections by the groove portion 93.

As shown in FIG. 1, a filter member 87 and a fastener 88 thereof are inserted in the air communication hole 91 of the grommet 9. The filter member 87 is a thin-film filter having a micron-sized network structure formed of, for example, a fluororesin such as PTFE (polytetrafluoroethylene), and is configured to be able to communicate with the atmosphere without passing water droplets or the like. is there. Further, the fastener 88 is a member formed in a tubular shape, and the filter member 87 is sandwiched between its outer circumference and the inner circumference of the atmospheric communication hole 91 and fixed to the grommet 9.
The groove 93 of the grommet 9 described above forms a flow path that guides water droplets or the like that could not pass through the filter member 87 to the outer peripheral side so as not to collect on the filter member 87. Therefore, it is preferable that the rear end of the filter member 87 is arranged on the rear end side of the groove portion 93 with respect to the bottom surface 94. The groove portion 93 may have an inclination from the front end side to the rear end side in the axis O direction from the outer side in the radial direction toward the center side.

Next, a metal tubular outer cylinder 3 extending in the axis O direction is assembled on the rear end side of the main metal fitting 5. As shown in FIG. 4, the outer cylinder 3 is formed of stainless steel such as SUS304 in a tubular shape extending along the axis O direction, and the tip portion 31 is located on the tip side (lower side in FIG. 4) from substantially the center. Is formed into a large diameter. The inner diameter of the tip portion 31 is formed to be larger than the outer diameter of the rear end engaging portion 58 in order to engage the tip portion 31 with the rear end engaging portion 58 (see FIG. 1) of the main metal fitting 5.
Further, as shown in FIGS. 3 and 4, the rear end of the rear end portion 38 located on the rear end side of the outer cylinder 3 is bent inward in the radial direction to form the connecting portion 32, and the connecting portion 32 is formed. Four plate-shaped arm portions 33 extending toward the axis O are projected from four locations in the circumferential direction of the above.

Each of the arm portions 33 is connected to the outer circumference of the circular plate-shaped protective portion 34. The protective portion 34 has an outer diameter substantially the same as that of the atmospheric communication hole 91 of the grommet 9 shown in FIG. 2, and as shown in FIGS. 1 and 3, the thickness direction is aligned with the axis O direction to communicate with the atmosphere. It is supported by the arm 33 so as to cover the hole 91. Further, as shown in FIG. 4, the protective portion 34 is provided with a protruding portion 35 projecting toward the rear end side. The opening provided in the protrusion 35 is formed smaller than the opening (size) of the atmospheric communication hole 91 (see FIG. 1) to prevent stepping stones and the like from entering the atmospheric communication hole 91. ..

Then, through the opening of the protrusion 35, ventilation between the outside and the inside of the air communication hole 91 (that is, ventilation between the inside and the outside of the outer cylinder 3) is secured. By providing the protection unit 34 in this way, the filter member 87 arranged in the atmospheric communication hole 91 can be protected from external impacts such as contact with plants and collisions with stepping stones, and damage can be prevented. it can. The protruding portion 35 is arranged on the tip side of the rear end facing surface 99 of the grommet 9 (that is, the protruding portion 35 is arranged in the grommet 9). As a result, it is possible to prevent the lead wire 18 from coming into contact with the protruding portion 35 and being damaged.

As shown in FIG. 1, the outer cylinder 3 having such a structure surrounds each side surface of the rear end portion 66, the separator 8 and the grommet 9 of the detection element 6 arranged in a row in the axis O direction in the circumferential direction. In this state, it is arranged on the rear end side of the main metal fitting 5. The tip portion 31 of the outer cylinder 3 is fitted on the outer circumference of the rear end engaging portion 58 of the main metal fitting 5, and is crimped inward in the radial direction from the outer peripheral side.
Further, the outer cylinder 3 is fixed to the main metal fitting 5 by performing laser welding around the outer circumference of the tip portion 31.

Further, the side surface of the outer cylinder 3 corresponding to the position of the portion on the tip end side of the flange portion 81 of the separator 8 is crimped inward in the radial direction around the outer circumference. A holding metal fitting 85 is arranged at this position, and the holding metal fitting 85 is crimped and held in the outer cylinder 3 while holding the separator 8 inside itself.
Further, the side surface of the outer cylinder 3 corresponding to the position of the portion on the rear end side of the flange portion 81 of the separator 8 is formed to have a smaller diameter than the flange portion 81 of the separator 8. That is, the front end facing surface of this small diameter portion comes into contact with the rear end facing surface of the flange portion 81. Then, the flange portion 81 is sandwiched between the tip facing surface of the small diameter portion and the holding metal fitting 85, and the movement of the separator 8 in the axis O direction is restricted.

Then, as shown in FIG. 1, the grommet 9 arranged on the rear end side of the separator 8 is arranged in the rear end 38 of the outer cylinder 3, and is directed toward the rear end of the grommet 9 divided into four sections. The surface 99 passes between the four arm portions 33 and projects from the outer cylinder 3 toward the rear end side, and the arm portion 33 is arranged in the groove portion 93 as shown in FIG.
At this time, it is preferable to arrange the arm portion 33 with a gap from the bottom surface 94 of the groove portion 93 because problems such as the arm portion 33 being caught in the groove portion 93 can be suppressed.

Further, as shown in FIG. 1, the rear end portion 38 of the outer cylinder 3 surrounding the outer periphery of the grommet 9 arranged in the rear end portion 38 of the outer cylinder 3 is applied inward in the radial direction together with the grommet 9 from the outer peripheral side. It is tightened to form the first crimping portion S1, and the grommet 9 is fixed to the outer cylinder 3.
Further, on the rear end side of the first crimping portion S1, the rear end portion 38 of the outer cylinder 3 surrounding the outer circumference of the grommet 9 is crimped inward in the radial direction from the outer peripheral side to press the second crimping portion S2. Is forming.

The first crimping portion S1 is formed by crimping the rear end portion 38 of the outer cylinder 3 relatively strongly, and the grommet 9 is radially inwardly reduced in diameter at the position of the first crimping portion S1 to remove the grommet 9. It is firmly fixed to the cylinder 3. Due to this reduced diameter, the grommet 9 on the rear end side of the first crimping portion S1 has a convex portion having a diameter larger than the diameter D1 of the first crimping portion S1 (diameter D2) and protruding outward in the radial direction. 9p is formed. That is, the first crimping portion S1 is formed by crimping so strongly that the convex portion 9p is formed, and is larger in diameter than the first crimping portion S1 at a position overlapping the convex portion 9p in the radial direction. Second crimping portion S2 is formed. That is, the convex portion 9p and the second crimping portion S2 are located on a vertical line perpendicular to the axis O. Further, the second crimping portion S2 is formed by crimping weakly so as not to come into contact with the convex portion 9p.

The first crimping portion S1 has a function of reducing the diameter of the grommet 9 inward in the radial direction and fixing the grommet 9 to the outer cylinder 3. In this case, when the outer cylinder 3 is strongly crimped and the grommet 9 is reduced in diameter inward so that the convex portion 9p is formed, the rear end side of the outer cylinder 3 is pulled by the first crimping portion S1 to expand the diameter. However, there is a possibility that a large gap may be formed between the rear end 3e of the outer cylinder 3 and the grommet 9.

Therefore, the outer cylinder 3 is crimped inward in the radial direction at a position on the rear end side of the first crimping portion S1 and overlapping the convex portion 9p in the radial direction to form the second crimping portion S2. It is possible to reduce or suppress the gap G generated by expanding the diameter of the rear end side of 3. Since the second crimping portion S2 may suppress or correct the diameter expansion of the outer cylinder 3, it does not have to be crimped more strongly than the first crimping portion S1 and has a larger diameter than the first crimping portion S1.
On the other hand, if the diameter of the second crimping portion S2 is the same as that of the first crimping portion S1 or smaller than that of the first crimping portion S1, the outer cylinder 3 is strongly crimped at the position of the second crimping portion S2. The diameter of the outer cylinder 3 is expanded on the rear end side of the second crimping portion S2.

The first crimping portion S1 and the second crimping portion S2 can be formed as shown in FIG. 5, for example. First,
In the example of FIG. 5, a crimping machine for crimping in all directions is used, and the crimping die 500 includes a first die surface 502 having a narrow opening diameter and a step portion on the rear end side of the first die surface 502. A second die surface 504 having an opening diameter wider than that of the first die surface 502 is used.
Then, when the rear end 38 of the outer cylinder 3 surrounding the outer circumference of the grommet 9 is crimped with the crimping die 500, the outer cylinder 3 is strongly crimped on the first die surface 502 having a narrow opening diameter, and the first The crimping portion S1 is formed.

Further, at this time, the rear end side of the outer cylinder 3 is pulled by the first crimping portion S1 to try to increase the diameter (two-dot chain line in FIG. 5), and the second die surface 504 having a wide opening diameter is suppressed or It is crimped relatively weakly so as to be corrected, and the second crimping portion S2 is formed at the same time.
In order to suppress or correct the tendency of the rear end side of the outer cylinder 3 to increase in diameter, it is difficult to suppress the diameter increase by springback simply by pressing the rear end side of the outer cylinder 3. Therefore, by weakly crimping the rear end side of the outer cylinder 3 to form the second crimping portion S2, the diameter expansion can be reliably suppressed or corrected.

As described above, by forming the second crimping portion S2 having a diameter larger than that of the first crimping portion S1, it is possible to suppress or correct the tendency of the rear end side of the outer cylinder 3 to increase in diameter due to crimping. The gap G between the outer cylinder 3 and the grommet 9 can be reduced or suppressed, and the gap corrosion of the outer cylinder 3 can be suppressed.

Further, since the rear end side of the outer cylinder 3 is crimped by the second crimping portion S2 having a diameter larger than that of the first crimping portion S1 (in other words, the crimping is weak), the rear end side of the outer cylinder 3 is crimped. It is possible to prevent the outer cylinder 3 from being distorted toward the rear end edge of the outer cylinder 3 and the outer cylinder 3 from being wrinkled, as compared with the case where the outer cylinder 3 is strongly crimped in the same manner as the first crimping portion S1. In particular, when the arm portion 33 having low strength is formed on the rear end side 38 of the outer cylinder 3 as described above, if the outer cylinder 3 is distorted or wrinkled, the arm portion 33 bends and interferes with the groove portion 93. However, since there is a risk that the arm portion 33 may be damaged, such a problem can be suppressed.
Further, as shown in FIG. 1, when the second crimping portion S2 is not in contact with the convex portion 9p, the degree of crimping of the second crimping portion S2 is further smaller, so that the outer cylinder 3 is distorted due to crimping. Wrinkles can be further suppressed.

The presence of the first crimping portion S1 can be determined by whether or not there is a portion where the outer cylinder 3 and the grommet 9 are reduced in diameter in the radial direction. Further, the presence of the second crimping portion S2 is due to the crimping scratches dented from the outer surface of the outer cylinder 3 due to the crimping die (for example, in the case of round crimping such as Happo round crimping, the outer cylinder 3 is peripherally peripheral. It can be judged by the presence or absence of crimping scratches that are dented at intervals in the direction.

It goes without saying that the present invention is not limited to the above embodiments and extends to various modifications and equivalents included in the ideas and scope of the present invention.
In the above embodiment, the outer cylinder is fixed to the rear end side of the main metal fitting, but is fitted to the rear end of another tubular body fixed to the rear end side of the main metal fitting, and is not directly fixed to the main metal fitting, for example. It may be in the form of a protective outer cylinder.
Further, the gap G between the outer cylinder and the grommet may be zero, but it may be difficult to keep the gap G at zero, so the gap G may be a certain value or less that can suppress the gap corrosion.
The sensor is not limited to the gas sensor, and may be a temperature sensor or the like. Further, examples of the gas sensor include an oxygen sensor and a NOx sensor.
The method for forming the first crimping portion and the second crimping portion is not limited to the above, and may be crimped in two stages with different dies. In this case, after crimping the first crimping portion, the second crimping portion may be crimped.

1 sensor (gas sensor)
3 Outer cylinder 5 Main metal fittings 6 Detection element 64 Detection unit 9 Elastic member (grommet)
9p Convex part 18 Lead wire 33 Arm 34 Protective part 87 Filter member 91 Atmospheric communication hole 92 Lead wire insertion hole 93 Groove 94 Bottom surface 95 Side surface 99 Rear end facing surface S1 1st crimping part S2 2nd crimping part O axis

Claims (2)

A detection element that extends in the axial direction and has a detection unit on its tip side,
A main metal fitting that surrounds the radial circumference of the detection element while projecting the detection unit from its own tip.
A metal tubular outer cylinder arranged on the rear end side of the main metal fitting,
An elastic member arranged inside the outer cylinder and closing the rear end side of the outer cylinder,
In the sensor equipped with
The outer cylinder has a first crimping portion formed by crimping inward in the radial direction together with the elastic member, and the elastic member has the first crimping portion on the rear end side of the first crimping portion. It has a convex part that protrudes radially outward from the tightening part, and has a convex part.
The outer cylinder is further have a second caulking portion of larger diameter than the first crimp portion at a position overlapping the convex portion and radially,
The sensor is characterized in that the second crimping portion is in non-contact with the convex portion and the inner diameter of the rear end edge of the outer cylinder is larger than the inner diameter of the first crimping portion . The elastic member is interposed with a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness, so that the inside and outside of the outer cylinder are interposed. Atmospheric communication holes that enable atmospheric communication are formed so as to extend in the axial direction.
Further, the elastic member extends outward in the radial direction from the atmospheric communication hole as a starting point on the rear end facing surface side thereof while avoiding the lead wire insertion hole, and is notched toward the tip end side of the elastic member. Has a groove with a bottom and sides,
A protective portion that protects the filter member by covering the atmospheric communication hole of the elastic member from the rear end side in the axial direction, and has an opening smaller than the opening of the atmospheric communication hole, and the protective portion. Along with connecting to the outer cylinder, at least a part of the arm portion extending in the radial direction and arranged in the groove portion of the elastic member is connected to the outer cylinder.
The sensor according to claim 1, wherein the arm portion is arranged with a gap from the bottom surface of the groove portion.

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