JP4921386B2 - Sensor - Google Patents

Description

  The present invention relates to a sensor, and more specifically, to detect the temperature of a gas sensor such as an oxygen sensor, a NOx sensor, an HC sensor, or the like for detecting the concentration of a specific gas component in exhaust gas discharged from an internal combustion engine, for example. It relates to a sensor such as a temperature sensor.

   Conventionally, a gas sensor including a sensor element whose electrical characteristics change according to the concentration of a specific gas component in exhaust gas is used for air-fuel ratio control of an automobile (Patent Document 1). FIG. 12 shows such a gas sensor 1. The gas sensor 1 includes, for example, a sensor element (detection element) 21 made of a solid electrolyte having oxygen ion conductivity, a metal shell (metal body) 11 for holding the sensor element 21, and a rear end of the metal metal 11 A metal protective cylinder (outer cylinder) 81 provided in an enclosing manner on the (upper end in the figure) side, a terminal fitting 51 electrically connected to the electrode terminal of the sensor element 21 in the protective cylinder, and the terminal fitting 51, a lead wire 61 connected to 51 and drawn out from the rear end of the protective cylinder 81, a terminal fitting 51, and a terminal disposed inside the protective cylinder 81 while maintaining insulation between the tips of the lead wires 61 connected thereto A metal fitting holding member (also referred to as a separator) 71 and a sealing elastic member (grommet) 101 for pulling out the lead wire 61 from the rear end to the outside of the protective cylinder 81 are formed. In this specification, regarding the sensor or its component or part (portion), “rear end” refers to the upper end of the sensor, component, etc. of FIG. 12, and “tip” refers to the opposite. It shall be the end (lower end).

  The elastic member 101 for sealing is disposed at the rear end of the protective cylinder 81 and has a lead wire insertion hole formed therethrough. And it is comprised so that they may be drawn outside through each lead wire (electric wire) 61 in this hole. However, the rear end portion of the protective cylinder 81 is formed into a sealing cylinder portion (cylindrical sealing cylinder portion) 83 which is narrowed to a reduced diameter and has a relatively small diameter. Is disposed in the sealing cylinder 83. Note that the outer shape of the elastic member 101 for sealing is substantially columnar so that the outer shape of the sealing elastic member 101 is just inside the cylindrical sealing cylinder 83 in a free state, and the diameter of the sealing cylinder 83 is reduced from the outer peripheral surface. By caulking (plastically deforming), the sealing elastic member 101 is compressed in the radial direction, so that the space between the inner peripheral surface of the sealing cylinder 83 and the outer peripheral surface of the sealing elastic member 101 and each lead are reduced. The seal in the hole through which the wire 61 is inserted is held.

  On the other hand, the terminal fitting holding member 71 is for securing insulation between the terminal fittings 51 and between the terminal fitting 51 and the protective cylinder 81, and is made of an electrical insulating material such as ceramic. In order to ensure insulation corresponding to the metal fitting 51 and the lead wire 61, each of the holes is provided with a hole that is partitioned by a wall extending forward and backward and formed so as to penetrate the front and rear. Each terminal fitting 51 is positioned and accommodated in the region while maintaining insulation.

By the way, such a terminal metal fitting holding member 71 has, for example, a flange 73 protruding outward on the outer peripheral surface thereof, and the flange 73 is a tip-facing surface (a downward surface of the flange 73 in FIG. 12). It is a supporting means for supporting, and is arranged by supporting or locking the front end facing surface of the flange 73 at the rear end (upper end in the figure) of the support member 91 fixed in the protective cylinder 81. In this way, the terminal metal fitting holding member 71 is arranged in such a manner that the movement toward the distal end side is restricted in the protective cylinder 81. On the other hand, on the rear end face side of the terminal metal fitting holding member 71, a sealing elastic member 101 fixed inside thereof is disposed by caulking the sealing cylinder portion 83 at the rear end of the protective cylinder 81 in a reduced diameter shape. Yes. On the other hand, the movement of the terminal metal fitting holding member 71 toward the rear end (the upper end in the figure) is restricted by setting the rear end so as to contact the front end of the sealing elastic member 101. That is, in the sensor 1 having the above-described configuration, the terminal fitting holding member 71 is disposed in the protective cylinder 81 so as to be sandwiched between the support member 91 and the sealing elastic member 101, and is positioned before and after. In the sensor 1 described above, the positioning of the terminal fitting holding member 71 in the radial direction depends on the tightening force obtained by caulking the support member 91 together with the protective cylinder 81 from the outside.
JP 2007-101411 A

  In the conventional sensor 1, the terminal fitting holding member 71 is positioned by the support member 91 provided in the protective cylinder 81 and the sealing elastic member 101 in the sensor axis G direction as described above. Is retained. On the other hand, when the sealing elastic member 101 is compressed in the radial direction by caulking, if the rear end of the terminal fitting holding member 71 is in contact with the tip of the sealing elastic member 101, after the caulking, Although it seems that the elastic member 101 for sealing stretches and deforms, the elastic member 101 for sealing presses the rear end of the terminal metal fitting holding member 71 toward the front end side. Is not obtained, and is substantially in a contact state. This is presumably because the outer peripheral surface side of the tip of the elastic member 101 for sealing is in a free state, and the tip easily deforms outward.

  That is, in the sensor 1 configured as described above, the movement of the terminal fitting holding member 71 is restricted by the support member 91 with respect to the front end side, but the rear end is the front end of the elastic member 101 for sealing. Thus, it is only supported in the contact state, and is not in a state of being positively compressed in the direction of the sensor axis G, that is, the front-rear direction. For this reason, it can be said that the supporting force or holding force in the front-rear direction of the terminal fitting holding member 71 in the protective cylinder 81 is weak. Therefore, the elasticity of the sealing elastic member 101 decreases due to thermal deterioration or the like, and the terminal fitting holding member 71 gradually becomes loosened due to external forces such as vibration and impact applied to the sensor 1, and eventually Support stability may be compromised. In such a state, the terminal fitting holding member 71 moves or vibrates in the protective cylinder 81. Thus, in the worst case, the terminal fitting 51 in the terminal fitting holding member 71 and the connecting portion between the terminal fitting 51 and the lead wire 61 are deformed or broken (poor conduction), or the internal sensor element 21 is damaged. There was a possibility of causing problems such as receiving.

  The present invention has been made in view of the above problems in the sensor of the conventional configuration described above. Among the supporting forces of the terminal fitting holding member in the protective cylinder, the supporting force in the front-rear direction is particularly increased to protect the sensor. The object is to effectively prevent the terminal fitting holding member from moving or vibrating in the cylinder.

In order to achieve the above object, the invention according to claim 1 includes a cylindrical metal shell, a sensor element disposed inside the metal shell,
A terminal fitting holding member made of an insulating material disposed on the rear end side of the sensor element;
A terminal fitting disposed in the terminal fitting holding member and connected to the electrode of the sensor element;
A cylindrical protective cylinder arranged so as to surround the outer peripheral surface of the terminal fitting holding member;
A lead wire connected to the terminal fitting and pulled out from the rear end of the protective cylinder,
The terminal fitting holding member is supported by a supporting means for restricting movement to the tip side,
The protective cylinder has, at its rear end part, a sealing cylinder part formed so as to have a relatively small diameter via an annular shoulder part continuous toward the axis line side,
Inside the sealing cylinder, an elastic member for sealing, in which the lead wire is inserted later, is disposed on the rear end side of the terminal fitting holding member, and the sealing cylinder is reduced in diameter. In the sensor in which the elastic member for sealing is compressed in the radial direction by being caulked,
At least a part of the terminal fitting holding member has a large diameter portion larger than the sealing cylinder portion,
The elastic member for sealing is integrally formed with a holding member pressing portion that is sandwiched between the tip-facing surface of the shoulder and the rear end of the large-diameter portion of the terminal metal fitting holding member,
The shoulder of the protective cylinder is provided with a recess recessed toward the distal end, and the recess compresses the holding member pressing portion toward the distal end, whereby the elasticity of the holding member pressing portion. The terminal fitting holding member is configured to be pressed against the support means.

  According to a second aspect of the present invention, in the holding member pressing portion, a compressive strain in a front-rear direction of a portion of the holding member pressing portion that is in contact with a front end facing surface of the shoulder portion and a rear end of the large-diameter portion of the terminal metal fitting holding member. 2. The sensor according to claim 1, wherein the recess is provided in the shoulder so as to be in a range of 10% to 30%.

  According to a third aspect of the present invention, the concave portion provided in the shoulder portion is provided so as to form an annular shape around the sealing cylinder portion when the protective cylinder is viewed from the rear end side. It is a sensor of Claim 1 or 2 characterized by these.

  The invention according to claim 4 is the sensor according to any one of claims 1 to 3, wherein the sealing elastic member is made of a rubber-like elastic body.

  According to a fifth aspect of the present invention, in place of the holding member pressing portion integrally formed with the sealing elastic member, the holding member pressing elastic member provided separately from the sealing elastic member; The sensor according to any one of claims 1 to 4, wherein the sensor is provided.

  In the first aspect of the present invention, the holding member pressing portion provided on the elastic member for sealing is compressed, so that the terminal fitting holding member is pressed against the support means by its elasticity. For this reason, compared with the conventional sensor structure, the holding force or the fixing force in the front-rear direction of the terminal fitting holding member (hereinafter also simply referred to as the holding member) can be increased by the amount of pressing. Therefore, according to the present invention, stable support can be obtained as compared with the support in the front-rear direction of the holding member in the conventional sensor. As a result, the terminal fitting holding member is effectively prevented from loosening or moving in the protective cylinder. As a result, the terminal fitting in the holding member and the connection portion between the terminal fitting and the lead wire are deformed or broken (poor conduction). This is effective in preventing the occurrence of damaging and damage to the internal sensor element.

  In order to stably increase the supporting force for the holding member, it is necessary to provide the holding member pressing part with a recess in the shoulder so that a pressing force by appropriate compression deformation is applied to the shoulder part. What is necessary is just to set according to the material of a member press part, ie, the elastic member for a seal | sticker, the thickness (dimension of a front-back direction), width (dimension of a radial direction), etc. of a holding member press part. In this case, if the compressive strain of the holding member pressing portion is less than 10%, the supporting force of the terminal metal fitting holding member is weak, while if it exceeds 30%, the deterioration due to heat tends to be accelerated. Therefore, it is preferable to provide the shoulder with a recess having such a depth that a compressive strain of 10 to 30% can be obtained as in the invention described in claim 2. In addition, like the invention of Claim 3, when providing a holding member press part and a recessed part cyclically | annularly, stability of the support of a terminal metal fitting holding member can be made high.

  In the present invention, as described above, the sealing elastic member is not particularly limited in material or composition, but as in the invention of claim 4, it is made of a rubber-like elastic body. Is preferred. As the synthetic rubber, fluorine (system) rubber is particularly preferable for a sensor attached to an engine because it has excellent durability such as heat resistance. However, it may be formed of a synthetic resin (plastic) that has a certain degree of elasticity and has moderate flexibility or flexibility. And even if it is set as any material, it is good also as what contains glass fiber, a resin fiber, etc.

  Further, it is preferable that the holding member pressing portion of the present invention is formed integrally with the sealing elastic member because the number of parts does not increase and the sensor structure is simplified. . However, in the present invention, as in the invention described in claim 5, the holding member pressing portion is provided separately from the sealing elastic member instead of being integrally formed with the sealing elastic member. The holding member pressing elastic member may be used. According to the present invention, a recess is formed in the shoulder portion of the protective cylinder and is provided with plastic deformation recessed toward the distal end, and the recess faces the holding member pressing elastic member toward the distal end. By compressing, the terminal fitting holding member is pressed against the support member by the elasticity of the holding member pressing elastic member. In this invention, the elastic member for pressing the holding member has the material, shape, and structure in consideration of only the action of compressing the holding member to the tip side without considering the sealing property like the elastic member for sealing. Can be set.

  Hereinafter, the best mode for carrying out the sensor of the present invention will be described in detail with reference to FIGS. However, this embodiment is embodied in the oxygen sensor 1 that detects the oxygen concentration in the exhaust gas. Therefore, first, the overall configuration of the oxygen sensor 1 (hereinafter also simply referred to as the sensor 1) will be described. The oxygen sensor 1 is provided with a detector (not shown) 21a on the inner side of a cylindrical metal shell 11 (hereinafter, also simply referred to as a main body 11) on the tip side (lower end side in the drawing) directed toward a measurement target. A sensor element (detection element) 21 made mainly of ceramic is disposed in a plate shape or a rod shape whose cross section is rectangular, and is fixed in an airtight manner. The metal shell 11 is concentrically formed in a stepped cylindrical shape so that its inner peripheral surface gradually increases in diameter from the front end (lower end in FIG. 1) toward the rear end (upper end in FIG. 1). A screw 12 for fixing to an engine exhaust pipe (not shown) is formed near the lower end of the surface.

  Inside the main body 11 and outside the sensor element (also simply referred to as element) 21, airtight holding and fixing means for holding the element 21 in an airtight manner is provided in a filling manner. This airtight holding and fixing means includes a cylindrical body 30 in which an inner collar is supported on a lower step inside the main body 11, and is disposed inside the cylindrical body 30 and on the inner collar. A holder 31 made of alumina and sealing materials (talc in this example) 32 and 33 are sequentially arranged. A sleeve 35 is disposed on the sealing material 33, and a thin caulking cylindrical portion 16 connected to the cylindrical portion 15 near the rear end of the main body 11 is bent inward via a ring washer 36. The element 21 is fixed in an airtight manner inside the metal shell 11 by compressing the rear end of the sleeve 35 toward the front end and compressing the internal sealing materials 32, 33 and the like.

  In the element 21 fixed in this way, the front end side (lower end side in FIG. 1) where the detecting portion 21a is provided protrudes a predetermined amount (length) from the front end surface of the main body 11, and the rear end (upper end in FIG. 1). The offset portion 23 is protruded by a predetermined amount (length) from the rear end surface of the main body 11 and the rear end surface of the sleeve 35. Further, the tip (detector 21a) of such an element 21 is covered with a protector (protective cover) 18 having a double structure provided with a plurality of holes (vent holes) so as to surround the periphery thereof. It is fitted and fixed to the tip of the main body 11. A large-diameter portion 19 formed on the outer periphery of the intermediate portion in the axis G direction of the main body 11 is a polygonal portion for screwing the main body 11 into an exhaust pipe (not shown). A gasket 20 for sealing is attached.

  Of the elements 21 arranged and fixed in the main body 11 in this way, both main surfaces (left and right in FIG. 1) of the rear end portion 23 projecting from the rear end (the upper end in the figure) of the sleeve 35 are illustrated. Although not, a plurality (three or two) of electrode terminals (metallized layers) are formed side by side. These electrode terminals are for taking out the detection output from the detection unit 21a and for applying a voltage to a heater (not shown) formed in the element 21 and are formed by simultaneous firing with the element 21. is there. The above description corresponds to the part of the element-side subassembly 201 in which the element 21 is fixed in the main body 11 in the lower left of FIG. The sensor 1 of this embodiment is manufactured by assembling the element-side subassembly 201 and the terminal metal fitting-side subassembly 301 shown in the upper right of FIG. 6 as will be described later.

  On the other hand, on the rear end side of the element 21, a cylindrical terminal fitting holding member 71 made of an insulating material (ceramic) is arranged coaxially with the metal shell 11, and a portion 23 near the rear end of the element 21 is inserted. ing. The terminal fitting holding member 71 has a flange 73 projecting outward on the outer peripheral surface 72a of the rear end (the upper end in the figure) of the cylindrical portion 72 in the circumferential direction, and is connected to each electrode of the element 21 inside. A terminal fitting 51 is disposed. That is, although not shown in detail inside the terminal fitting holding member 71, it is formed in a penetrating manner after the end, and insulation is held by a wall (partition wall) in which each adjacent terminal fitting 51 extends forward and backward. , And a hole 70 formed so as to be disposed so as to sandwich the rear end portion 23 of the element 21 as shown in the figure, and each terminal fitting 51 is disposed through the hole 70. Has been. In this embodiment, the flange 73 forms a large-diameter portion that is larger in diameter than a sealing cylinder portion 83 to be described later.

  That is, in this embodiment, the rear end portion 23 of the element 21 is inserted between the opposing terminal fittings 51 arranged in the terminal fitting holding member 71, and the electrode terminals and the terminal fittings 51 are connected to each other. Has been. In addition, each terminal metal fitting 51 is formed of a metal plate having a spring property, and among the connection spring portions 54 bent in a folded shape, an inward mountain portion having an arc shape or a “<” shape is formed. Each of the electrodes is electrically connected by being pressed against each electrode by the spring property. Further, the barrel 52 at the rear end (upper end in the drawing) of each terminal fitting 51 has a core wire at the tip of the lead wire 61 drawn out from the rear end (shown end) of the metal protective cylinder 81 described below. Are connected by caulking. In this embodiment, the terminal fittings 51 are arranged so as to be surrounded in the terminal fitting holding member 71 in this way.

  On the other hand, on the outside of the terminal fitting holding member 71, a cylindrical cylinder 81 having a different diameter that forms a casing through a space K is disposed so as to surround the terminal fitting holding member 71. The protective cylinder 81 has a sealing cylinder 83 formed coaxially and cylindrically so as to have a relatively small diameter via an annular shoulder 84 connected to the rear end thereof toward the axis G side. . The protective cylinder 81 has a large-diameter cylinder part 82 having a relatively large diameter with respect to the sealing cylinder part 83 at the tip (lower end in the figure). And the front-end | tip of this protection cylinder 81 is externally fitted in the cylindrical part 15 of the metal fitting 11 near the rear end, and the outer peripheral surface of the external fitting part is fixed to the main body 11 by, for example, welding after caulking. In this embodiment, in the large-diameter cylindrical portion 82 of the protective cylinder 81, the rear end portion 80 is formed to have a relatively small diameter as compared with the front end portion.

  In the present embodiment, the rear end 93 is bent inward in the longitudinal section in the annular space K between the inner peripheral surface of the large-diameter cylindrical portion 82 of the protective cylinder 81 and the terminal metal fitting holding member 71. A support member 91 for a cylindrical holding member is disposed coaxially and fixed to the inner surface of the protective cylinder 81. The support member 91 has a cylindrical plate wall portion 92 formed in a substantially cylindrical shape from a metal plate (thin plate), and the rear end 93 of the cylindrical plate wall portion 92 itself is bent inward to form an inward flange. Following this inward flange, it has a spring piece 95 which is bent inwardly. The support member 91 is deformed into a reduced diameter by caulking an intermediate portion of the large diameter cylindrical portion 82 of the protective cylinder 81 into a reduced diameter toward the axis G direction, and the spring piece 95 is deformed by the deformation. It is pressed against the outer peripheral surface 72 a of the holding member 71 and fixed inside the protective cylinder 81. On the other hand, in this embodiment, the folded portion which is the rear end (upper end in FIG. 1) 93 of the support member 91 is arranged to be engaged with the front end facing surface 74 of the flange 73 of the terminal fitting holding member 71. That is, in this embodiment, such a support member 91 serves as a support means and restricts the holding member 71 from moving toward the distal end side.

  Next, the sealing elastic member 101 will be described. In this embodiment, the sealing elastic member 101 into which the lead wire 61 has been inserted is connected to the inside of the sealing cylinder portion 83 of the protective cylinder 81, and the tip 105 thereof is connected to the rear end (upper end in the figure) of the terminal fitting holding member 71. The sealing elastic member 101 is compressed in the radial direction by caulking the sealing cylinder 83 in a reduced diameter in this state. However, the sealing elastic member 101 is made of, for example, fluororubber, and in a free state (before caulking), the surface facing the front end of the shoulder 84 of the protective cylinder 81 (illustration inside) with respect to a portion closer to the front end (lower end in FIG. 1). Holding member pressing portion 103 having an outer diameter larger than that of the main body portion 102 of the sealing elastic member 101 so as to be sandwiched between the downwardly facing surface 84a and the rear end 75 of the terminal fitting holding member 71 (flange 73). Are integrally formed (see FIGS. 4 to 6). Thereby, in this example, the elastic member 101 for a seal | sticker is exhibiting the column shape of a concentric and different diameter which has a large diameter part in the front end side in a free state.

  In the free state, the outer diameter of the large diameter portion forming the holding member pressing portion 103 is substantially the same as the outer diameter of the rear end (flange 73) of the holding member 71, and the outer diameter of the main body portion 102 forming the small diameter portion is It is the same as the inner diameter of the sealing cylinder portion 83 before crimping, or an outer diameter that can be easily loaded into the sealing cylinder portion 83 in a gap-fitted state. (Refer to FIGS. 4 to 6) And, the lead wire 61 is inserted into the hole 106 formed along the axis G first, but the hole 106 is a portion closer to the tip. The thickness portion corresponding to the member pressing portion 103 has a relatively large diameter so that part or all of the barrel portion 52 of the terminal fitting 51 is accommodated. In addition, each thickness of the main-body part 102 and the holding member press part 103 is made substantially the same in this example. Thus, by caulking the sealing cylinder 83 to a reduced diameter, the gap between the inner peripheral surface of the sealing cylinder 83 and the outer peripheral surface of the main body 102 of the sealing elastic member 101 and each hole 106 is reduced. A seal between the inner peripheral surface and the outer peripheral surface of each lead wire 61 is held.

  On the other hand, in the present embodiment, in the state where the sealing cylinder 83 is reduced in diameter and the sealing elastic member 101 is compressed, the shoulder 84 of the protection cylinder 81 is recessed toward the tip side. A recess 86 is provided to which the plastic deformation of the shape to be provided is applied (see FIGS. 1 and 2). However, the recess 86 is provided in an annular shape so that a portion of the annular shoulder portion 84 close to the sealing cylinder 83, that is, a portion close to the axis G, extends along the circumferential direction of the sealing cylinder 83 (see FIG. 3). As indicated by a two-dot chain line in FIG. 2, the recess 86 has a shoulder 84 before the deformation on a plane perpendicular to the axis G, whereas a portion closer to the sealing cylinder 83 has a groove shape. Thus, a groove-like recess 86 that is recessed is formed. That is, when the sensor 1 is viewed from the rear end side, the concave portion 86 has an annular shape and is recessed at the shoulder portion 84 toward the front end side.

  Prior to the formation of the recess 86, the rear end surface 104 and the front end surface 105 of the holding member pressing portion 103 in the sealing elastic member 101 are connected to the front end facing surface 84 a of the shoulder 84 and the holding member 71 (flange 73). The holding member pressing portion 103 is sandwiched between the rear end 75 and the rear end 75 by compressive deformation at the tip end due to the formation of the concave portion 86. That is, what is important in the present invention is that the holding member pressing portion 103 is compressed toward the distal end side by providing such a concave portion 86, and the terminal metal fitting holding member 71 is compressed by the elasticity of the holding member pressing portion 103. Is pressed against the support member 91 (is pressed). As a result, the holding member 71 is stably held later in the sensor. Note that, by such compression, the outer peripheral surface of the holding member pressing portion 103 is deformed into a round shape that protrudes outward. In this embodiment, the outer peripheral surface of the holding member pressing portion 103 is also in this state. And an inner circumferential surface of the protective cylinder 81 are set so that an annular space K is formed (see FIGS. 1 and 2). By providing this space K, a heat insulating zone is secured, and even if the protective cylinder 81 becomes high temperature, heat is not directly transferred to the holding member pressing portion 103, thereby preventing thermal degradation of the portion. ing. Incidentally, in this embodiment, the depth of the concave portion 86 is set so that the compressive strain (compression ratio) in the front-rear direction of the holding member pressing portion 103 is in the range of 10 to 30%.

  In addition, it is as follows when the assembly of the terminal metal fitting side subassembly 301 shown to the upper right figure of FIG. 6 is explained in full detail (refer FIG. 4, FIG. 5). That is, the end portions (tips) of the lead wires 61 are passed through the holes 106 for inserting the lead wires of the elastic member 101 for sealing and through the holes 70 provided in the holding member 71, The core part of the end is connected by caulking to the barrel part 52 at the rear end of the terminal fitting 51 so that the inward ridges of the opposing terminal fitting 51 face each other. Next, the lead wire 61 is pulled back (upward in the figure) so that the rear end (upper end in the figure) 75 of the holding member 71 and the front end (lower end in the figure) 105 of the sealing elastic member 101 are in contact with each other. Then, the support member 91 is externally fitted to the outer peripheral surface 72a of the holding member 71 from the front end side (the lower side in the drawing), the rear end portion 93 is brought into contact with the front end facing surface 74 of the flange 73, and is folded inside. The formed spring piece 95 elastically presses the outer peripheral surface 72 a of the holding member 71. Next, the protection cylinder 81 is relatively covered from behind (the upper side in the drawing) so as to surround the sealing elastic member 101 and the holding member 71. At this time, as shown in FIG. 5, the annular shoulder portion 84 located at the boundary between the sealing cylinder portion 83 and the large-diameter cylinder portion 82 at the rear end of the protective cylinder 81 is a holding member for the sealing elastic member 101. The rear end 104 of the pressing portion 103 is hit and the front end 105 of the holding member pressing portion 103 is brought into contact with the rear end 75 of the holding member 71. Next, in this state, of the outer peripheral surface of the large-diameter cylindrical portion 82 of the protective cylinder 81, the portion 85 corresponding to the front and rear intermediate portion of the support member 91 is crimped so as to reduce (narrow) the diameter (see FIG. (See the upper right figure). Thus, when the intermediate portion of the support member 91 is narrowed down and fixed to the inner peripheral surface of the protective cylinder 81, the holding member 71 has a front end facing surface 74 of the flange 73 at the rear end (upper end in the drawing) 93 of the support member 91. Is held in a state in which the movement toward the tip side is restricted.

  Next, as shown in FIG. 6, the rear end portion 23 of the element side subassembly 201 of the terminal fitting side subassembly 301 assembled in this way is connected to the terminal fitting side subassembly 301. Both the semi-assemblies 201 and 301 are made to coincide with each other's axis G so as to be sandwiched between the opposing terminal fittings 51 in the terminal fitting holding member 71. Then, the rear end portion 23 of the element 21 is inserted between the terminal fittings 51 facing each other so as to be close to each other. At the same time, the leading end of the large-diameter cylindrical portion 82 of the protective cylinder 81 is fitted into the cylindrical portion 15 near the rear end of the metal shell 11, and the fitting portion is crimped from the outer peripheral surface side and then fixed by welding. .

  Then, as shown in FIG. 2, the main body 102 of the sealing elastic member 101 is compressed in the radial direction by caulking the sealing cylinder 83 at the rear end (upper end in the figure) of the protective cylinder 81 so as to reduce the diameter. . Then, the shoulder portion 84 is provided with a concave portion 86 by applying plastic deformation so as to be recessed toward the distal end side, and the concave portion 86 faces the holding member pressing portion 103 in the elastic member 101 for sealing toward the distal end side. By compressing, the holding member pressing portion 103 presses the holding member 71 against the support member 91 (that is, toward the distal end side). The concave portion 86 may be provided by plastic deformation at the same time as the sealing cylinder 83 is crimped to reduce the diameter, or as described above, separately from the sealing cylinder 83. Good.

  According to the sensor 1 of the present embodiment configured as described above, the holding member 71 is in a state in which the movement of the holding member 71 to the front end side is restricted by the support member 91 in the protective cylinder 81. On the other hand, in this state, the holding member pressing portion 103 of the sealing elastic member 101 is compressed between the rear end (illustrated upper end) 75 of the flange 73 of the holding member 71 and the shoulder portion 84. It is in the state. Therefore, the front end 105 of the holding member pressing portion 103 elastically presses the rear end 75 of the holding member 71 toward the front end by the amount of the compressive strain (deformation). That is, in this example, the terminal fitting holding member 71 is held in the protective cylinder 81 with a large supporting force or fixing force in the front-rear direction by the amount of such pressing. Therefore, in comparison with the support for the holding member in the conventional sensor, in the present invention, the support of the holding member 71 in the protective cylinder 81, particularly in the front-rear direction, becomes stable. Thus, it is possible to effectively prevent the terminal fitting holding member 71 from relaxing or moving in the protective cylinder 81.

  In the above embodiment, the holding member pressing portion 103 formed integrally with the sealing elastic member 101 is exemplified as a large-diameter columnar shape, that is, a shape whose outer shape is a circle when viewed from the rear end side. It is not limited to such a thing. That is, the holding member pressing portion 103 may be anything that is sandwiched between the leading end facing surface 84a of the shoulder portion 84 and the rear end 75 of the flange 73 of the holding member 71 and presses the holding member 71 to the tip end side. Specifically, it may be formed like a tooth of an external gear when viewed from the rear end side.

  In the above description, the concave portion 86 of the shoulder portion 84 is embodied as a cross-section and a V-groove shape, but can be embodied as a cross-section and a U-groove shape as the concave portion 86 shown in FIG. Further, the concave portion 86 of the shoulder portion 84 is not limited to the one having an annular shape in the circumferential direction of the sealing cylinder portion 83 as described above. That is, the concave portion only needs to be configured such that the holding member is pressed against the distal end side by the elasticity by compressing the holding member pressing portion toward the distal end side. Therefore, as shown in FIGS. 8 and 9, the recess 86 in the present invention may be divided into a plurality of portions with an angular interval around the axis as viewed from the rear end side.

  And in the said form, although the holding member press part 103 was integrally formed in the rear-end side of the sealing elastic member 101, it replaces with the holding member pressing part 103 integral with such a sealing elastic member 101, and FIG. 10, the holding member pressing elastic member 123, which is a separate body (separate part) from the sealing elastic member 101, is interposed between the shoulder portion 84 and the holding member 71, and A concave portion 86 may be provided, and the holding member 71 may be elastically pressed to the distal end side by the holding member pressing elastic member 123. FIG. 11 shows a state before the diameter of the sealing cylinder portion 83 is reduced and before the holding member pressing elastic member 123 is compressed. 10 and 11, the same parts as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In this case, the parts are provided in the sealing cylinder 83. The sealing elastic member 101 is only a portion corresponding to the main body 102 in FIG. That is, the example shown in FIGS. 10 and 11 is also obtained by dividing the sealing elastic member 101 in FIG. 2 at the front end facing surface 84 of the shoulder portion 84.

  The sensor of the present invention is not limited to the one described above, and can be embodied with appropriate modifications without departing from the gist thereof. For example, in the above, the case where the holding member pressing portion 103 is directly sandwiched between the front end facing surface 84a of the shoulder portion 84 and the rear end 75 of the flange 73 of the holding member 71 is illustrated. It may be sandwiched indirectly via another member such as a flat washer. In the above description, the support member 91 is used as a support means for restricting the movement of the holding member 71 toward the front end. However, such a support means may be formed on the inner surface of the protective cylinder itself, It may be provided at the rear end of the metal fitting 11, or the metal shell 11 itself can support the holding member 71. Further, in the above description, the holding member 71 is provided with the flange 73. For example, even if the cylindrical portion 72 of the holding member 71 and the flange 73 have the same outer diameter (that is, cylindrical shape), As long as the diameter is large.

  In the above embodiment, the sensor is embodied in a sensor having a long plate-like element. However, the sensor of the present invention is a hollow shaft-like element having a closed tip, and oxygen on its inner and outer surfaces. The present invention can be embodied in a sensor that measures the oxygen concentration of the measurement target gas based on the electromotive force generated corresponding to the concentration difference, and can also be embodied in other sensors such as a temperature sensor.

The front longitudinal cross-sectional view explaining the embodiment of the sensor of this invention. The principal part enlarged view of FIG. 1, and the further enlarged view of the shoulder part. FIG. 3 is a cross-sectional view taken along line AA for explaining the shoulder portion in FIG. 2 (viewed from the rear end side). The figure explaining the process of assembling the gas sensor of FIG. The figure explaining the process of assembling the gas sensor of FIG. The figure explaining the process of assembling the gas sensor of FIG. The principal part enlarged view which shows the other example of a recessed part. The enlarged plan view of the shoulder part seen from the rear end side of the sensor which shows another example of a recessed part. FIG. 9 is a cross-sectional view taken along the line BB for explaining the shoulder in FIG. 8 (viewed from the rear end side). The principal part expanded sectional view which replaced the holding member press part and showed the Example using the elastic member for holding member press. The figure which showed the state before the diameter reduction of the cylinder part for a seal | sticker in FIG. 10, and before the elastic member for a holding member press is compressed. The longitudinal cross-sectional front view explaining the conventional sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sensor 11 Main metal fitting 21 Sensor element 51 Terminal metal fitting 61 Lead wire 71 Terminal metal fitting holding member 72a Outer peripheral surface 73 of terminal metal fitting holding member Flange (large diameter part)
75 Terminal metal holding member rear end 81 Protective cylinder 83 Sealing cylinder 84 Shoulder 84a Shoulder tip end face 86 Recess 91 Support member (support means)
101 Elastic member 103 for sealing Holding member pressing part 123 Elastic member G for holding member pressing Axis

Claims (5)

A cylindrical metal shell, and a sensor element disposed on the inside of the metal shell,
A terminal fitting holding member made of an insulating material disposed on the rear end side of the sensor element;
A terminal fitting disposed in the terminal fitting holding member and connected to the electrode of the sensor element;
A cylindrical protective cylinder arranged so as to surround the outer peripheral surface of the terminal fitting holding member;
A lead wire connected to the terminal fitting and pulled out from the rear end of the protective cylinder,
The terminal fitting holding member is supported by a supporting means for restricting movement to the tip side,
The protective cylinder has, at its rear end part, a sealing cylinder part formed so as to have a relatively small diameter via an annular shoulder part continuous toward the axis line side,
Inside the sealing cylinder, an elastic member for sealing, in which the lead wire is inserted later, is disposed on the rear end side of the terminal fitting holding member, and the sealing cylinder is reduced in diameter. In the sensor in which the elastic member for sealing is compressed in the radial direction by being caulked,
At least a part of the terminal fitting holding member has a large diameter portion larger than the sealing cylinder portion,
The elastic member for sealing is integrally formed with a holding member pressing portion that is sandwiched between the tip-facing surface of the shoulder and the rear end of the large-diameter portion of the terminal metal fitting holding member,
The shoulder of the protective cylinder is provided with a recess recessed toward the distal end, and the recess compresses the holding member pressing portion toward the distal end, whereby the elasticity of the holding member pressing portion. The sensor is configured to press the terminal fitting holding member against the support means.   The compressive strain in the front-rear direction of the portion of the holding member pressing portion that comes into contact with the front-facing surface of the shoulder and the rear end of the large-diameter portion of the terminal fitting holding member is in the range of 10% to 30%. The sensor according to claim 1, wherein the recess is provided in the shoulder so that   3. The concave portion provided in the shoulder portion is provided so as to form an annular shape around the sealing cylinder portion when the protective cylinder is viewed from the rear end side. Sensor.    The sensor according to claim 1, wherein the elastic member for sealing is made of a rubber-like elastic body.   2. The holding member pressing elastic member, which is provided separately from the sealing elastic member, instead of the holding member pressing portion integrally formed with the sealing elastic member. The sensor of any one of -4.

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