JP3515857B2 - Exhaust gas sensor lead wire connection mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas sensor for measuring oxygen concentration, nitric oxide concentration and the like. Such an exhaust gas sensor is used for an air-fuel ratio sensor that detects an economical operation air-fuel ratio and a high-load air-fuel ratio in order to achieve a required air-fuel ratio, or is used for detecting a theoretical air-fuel ratio. Mounted on.

[0002]

2. Description of the Related Art As a gas detecting element body, one using BaSnO ₃ or one using a solid electrolyte made of a ceramic plate such as zirconia having oxygen ion conductivity is known. In addition, transition metal oxides (TiO ₂ , Ti
SrO ₃ or the like) is used to detect the change in the electric resistance value due to the atmospheric gas.

As a known exhaust gas sensor using this gas detecting element, as shown in FIG. 8, a gas is provided inside a tubular body formed by connecting an outer cylinder b to the rear end of a tubular base metal fitting a. An exhaust gas sensor s having a structure in which a detection element body c is held by an insulating protective layer d and its tip is exposed from the insulating protective layer d to form a detection end is proposed in Japanese Utility Model Publication No. 1-165456. ing.

[0004]

By the way, in the connection between the gas detecting element body c of the exhaust gas sensor s and the external control device, the lead wire f is directly taken out from the lead wire holding member e in the outer cylinder b. To connect to an external control device. By the way, the mounting portion of the exhaust gas sensor s is mounted in a deep portion of the engine room such as an exhaust pipe, and further on the lower surface portion of the pipe, etc. Therefore, the connecting work is troublesome due to the lead wire, or the lead wire is attached. There was a problem such as twisting. Furthermore, lead wire breakage,
In the case of connection failure, it was necessary to remove the entire exhaust gas sensor, which was troublesome.

Therefore, as shown in FIG. 9, the present inventors have provided a terminal holding portion o at the end portion of the outer cylinder n connected to the rear end portion of the tubular base metal fitting m, and the terminal holding portion o is provided at the terminal holding portion o. An improved product was studied in which the rod-shaped terminal p was held, the rod-shaped terminal p was projected from the rear end, and the connector q connected to the lead wire was fitted to the rod-shaped terminal p.

However, in such a structure, the connecting portion between the rod-shaped terminal p and the connector q is not sufficiently waterproofed,
Since this exhaust gas sensor is fixed to the lower portion of the exhaust pipe where rainwater tends to adhere in the engine room, a short circuit is likely to occur due to intrusion of water. Further, when the vehicle equipped with the exhaust gas sensor travels, the connector q is easily damaged by stone bounces, etc., and thus the connector q is easily damaged or the connection is apt to be poor. It is an object of the present invention to provide a lead wire connecting mechanism for an exhaust gas sensor that facilitates connection of lead wires, maintains watertightness of the connecting portion, and is resistant to external impact.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a gas detecting element body is disposed inside a tubular body formed by connecting an outer cylinder to a rear end portion of a tubular base metal member while being held by an insulating protective layer. In the exhaust gas sensor, the detection part of the tip of which is exposed to the front from the insulating protective layer to serve as the detection end, and the inside of the rear end of the outer cylinder is used as a connector mounting port that opens outward, and the gas detection element is provided on the insulating protective layer. A terminal pin that is electrically connected to a required electric circuit of the body is implanted, and the terminal pin is projected from the insulating protective layer into the connector mounting port and is fitted to the connector mounting port of the outer cylinder. Hold the connection terminal connected to the lead wire in the packaging,
A connector having a lead wire that is liquid-tightly drawn out from a ceiling portion of the fitting cylinder is provided, and the connection terminal is connected to the terminal pin in a state where the connector is fitted to the connector mounting opening. Is a lead wire connecting mechanism for an exhaust gas sensor.

Here, in order to maintain the state in which this connector is fitted in the connector mounting port, an engaging projection is provided around the rear end of the tubular base metal fitting, and the end of the fitting cylinder of the connector is described above. A configuration is proposed in which a locking projection that engages with the engagement projection is formed inward. Further, a male screw may be formed on the peripheral surface of the tubular base metal member, and a female screw that is screwed to the male screw may be provided on the inner periphery of the lower end of the fitting cylinder of the connector.

In such a structure, the terminal pin and the connection terminal are connected in the fitting cylinder in the fitted state of the connector. Therefore, the fitting cylinder maintains the watertightness of the connection portion, and the fitting cylinder protects the connection portion even if a stone or the like collides from the outside. Further, in the above-mentioned connector holding means, the connector is firmly held by the exhaust gas sensor.

[0010]

1 and 2, an embodiment of an exhaust gas sensor S according to the present invention and a connector 30 for ensuring its electrical connection will be described. 1 is a hexagonal rotation operation unit 2
And a tubular base metal fitting around which a male screw portion 3 is provided, a connecting portion 4 is connected to the rear of the rotating operation portion 2 (upper side in the drawing), and an annular engagement is provided at an end portion of the connecting portion 4. The engaging projection 5 is formed to project, and a thin caulking portion 6 is connected to the rear portion of the engagement projection 5. In addition, in the base metal fitting 1, a front reduced diameter hole portion 7a,
A through hole 8 composed of a large diameter hole portion 7b at the rear portion is formed, and a step portion is formed between the hole portions 7a and 7b.

Then, the caulking portion 6 is provided with stainless steel (SUS3
04) and the like, the lower end of a metal outer cylinder 10 is externally fitted, and laser welding 13 is applied to the periphery to be solidified.
The tubular body is configured by fitting the protective cylinder 14 therein. The outer cylinder 10 has a rear end having a large diameter and serves as a connector mounting port 11 that opens outward.

In this tube, a high heat resistance having a U-shaped cross section, which is made of a square-insulated porcelain tube such as alumina, zirconia, mullite, or spinel, in which a long plate-shaped gas detecting element body 20 is inserted in a hole 16. The property holding piece 15 is attached, and the gas detecting element body 20 is projected from the hole 16 and positioned in the reduced diameter hole portion 7a. Then, crimp the crimp portion 6 inward,
The holding piece 15 is held irremovably.

FIG. 3 shows the structure of this gas detecting element body 20, in which two platinum wires 22a, 22 are provided on a ceramic substrate 21.
b through the window hole 23 formed in the front half
The platinum wires 22a and 22b are exposed, and BaS is inserted into the window hole 23.
By embedding the sensor element 24 (detection section) made of nO ₃ or the like,
The sensor element 24 is connected to the platinum wires 22a and 22b.
Then, the surface of the sensor element 24 is further covered with a sprayed film 25 made of MgAl ₂ O ₄ or the like. Thus, the sensor element 24 is disposed in the protective cylinder 14, and the sensor element 24 reacts with oxygen to extract the potential difference from the two platinum wires 22a and 22b.

As the gas detecting element body, a plurality of substrates made of zirconia or the like serving as a solid electrolyte are laminated, and an alumina plate on which a heating resistor such as platinum, tungsten or molybdenum is formed is arranged on both sides or one side. Various configurations can be proposed, such as an oxygen detection element configured by the above laminated body.

Further, the platinum wire 22b is connected to the outer cylinder 10 and body-grounded, and the platinum wire 22a is connected to the terminal pin 26. The large diameter hole 7b is filled with an insulating protective layer 27 made of glide stone or the like, and the platinum wire 22
a and 22b are embedded in the insulating protective layer 27, and the terminal pins 26 are provided from the insulating protective layer 27 along the center of the outer cylinder 10.
It is designed to project. Thus, the exhaust gas sensor S is constructed.

In such a structure, the connector 30 is fitted onto the connector mounting port 11 of the outer cylinder 10. The structure of the connector 30 will be described.

This connector 30 has a front end made of metal opened, and a connection fitted externally to the terminal pin 26 in a ceiling-shaped fitting cylinder 31 having a ceiling portion having a lead wire insertion hole 35 at the rear end. It holds the terminal 32. To describe this configuration in more detail, the inner part of the fitting cylinder 31 is slightly reduced in diameter to serve as a holding part, and the holding part 33 is provided with a synthetic resin holding member 33 having an insertion hole formed therein. , This holding member 3
The lead wire 39 drawn out from the lead wire insertion hole 35 and the connection terminal 32 crimp-connected to the lead wire end portion of the lead wire 39 are inserted and held in the through hole of the lead wire 3.

On the front surface of the holding member 33, a rubber packing 34 having the same diameter as that of the holding member 33 is fitted.
Further, the front portion of the fitting cylinder 31 has a large diameter portion, and its inner diameter is made substantially equal to the outer diameter of the connector mounting port 11 of the outer cylinder 10. The fitting position of the packing 34 is located on the large-diameter portion side, and a gap into which the connector mounting port 11 is inserted is formed between the peripheral surface of the packing 34 and the inner surface of the large-diameter portion.

Further, on the inner peripheral surface of the front end of the fitting cylinder 31, there is formed an engaging projection edge 36 which engages with the engaging projection 5 of the base metal fitting 1.

In such a structure, when the connector 30 is externally fitted and pushed into the connector mounting port 11 of the outer cylinder 10,
The locking projection 36 is bent outward to some extent, spreads, rides over the engagement projection 5, and passes through, and the engagement projection 36 engages with the engagement projection 5 in the disengagement direction. Then, in this state, the end edge of the connector mounting port 11 is fitted between the packing 34 and the inner surface of the fitting cylinder 31, and the connecting terminal 32 is fitted on the terminal pin 26, whereby the connecting terminal 32 is connected as shown in FIG. The terminal 32 and the terminal pin 26 are electrically connected. At that time, the packing 34 is in a state of being pressed by the inner stepped seating surface of the connector mounting port 11 and the holding member 33. The packing 34 may be formed by an O-ring.

In addition, a gasket 38 is externally fitted to the base of the male screw portion 3 in order to maintain close contact with the installation portion.

In this structure, the connecting portion between the connecting terminal 32 and the terminal pin 26 is protected by the connector 30,
Even if a stone collides from the outside, the connector 30 protects the connecting portion. Further, when exposed to rainwater, the water once enters between the fitting cylinder 31 and the outer cylinder 10 and further propagates on the outer surface of the packing 34, but the connector mounting port 11 and the holding member 33 are used. By the pressing force of and, due to the rubber elastic sealing property of the packing 34, the contact of moisture with the connection terminal 32 is sufficiently prevented, and the watertightness is secured.

4 and 5 show an embodiment in which another holding means for the connector 30 is provided. Here, the same components as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this structure, a male screw 40 is formed on the rear connecting portion 4 of the hexagonal rotation operating portion 2 of the base metal fitting 1. A female screw 41 that is screwed into the male screw 40 is formed on the inner periphery of the front end edge of the fitting cylinder 31. A blocking collar 42 is formed at the rear end of the outer cylinder 10.

Thus, as shown in FIG. 5, the connector 30
When the female screw 41 is screwed onto the male screw 40 by rotating, the peripheral edge of the blocking collar 42 formed at the rear end of the outer cylinder 10 is fitted into the fitting cylinder 31.
Contact the inner surface of. Therefore, the connector 30 is screwed and firmly fixed to the exhaust gas sensor S, and
The male screw 40 and the female screw 41 cause a water draining action, and further, the moisture that has entered from the screw groove between the male screw 40 and the female screw 41 is blocked by the rubber elasticity of the packing 34 due to the pressing force of the blocking collar 42 and the holding member 33. I am trying to do it.

6 and 7 show a reference example in which another holding means for the connector 30 is further provided. In such a configuration, on the peripheral surface of the connector mounting port 11 of the outer cylinder 10,
The male screw 50 is formed. Then, the fitting cylinder 31
A female screw 51 that is screwed into the male screw 50 is formed on the inner periphery of the rear portion.

Thus, as shown in FIG. 7, the connector 30
The connector 30 is firmly fixed to the exhaust gas sensor S by rotating the and screwing the female screw 51 to the male screw 50, and the same draining action as in the embodiment of FIG. I try to cut off as much as possible.

In each of the above-described embodiments, the connector 30 protects the connecting portion against external impact, and the required watertightness in the connector 30 can be maintained, so that the electrical connection can be maintained. Short circuit, the disconnection of the connection part due to external impact or the like, and the corrosion of the connection part due to the intrusion of moisture, electrical short circuit, etc. can be prevented, and by providing a connector structure,
There is an advantage that the sensor can be easily attached to required parts and wiring.

[0028]

As described above, according to the present invention, the inside of the rear end of the outer cylinder 10 is used as the connector mounting opening 11 which opens outward, and the terminal pin 26 for connecting the gas detecting element body 20 to the insulating protective layer 27. , And the terminal pin 26 is projected from the insulating protection layer 27 into the connector mounting port 11 and is fitted to the connector mounting port 11 of the outer cylinder 10 in a heavenly fitting tube 10.
Since the connector 30 holding the connection terminal 32 connected to the lead wire 39 is externally fitted to the connector mounting opening 11, the connection terminal 32 is connected to the terminal pin 26. Due to the connector connection structure, the exhaust gas sensor S can be attached to the required pipeline without being hindered by the lead wire 39, and the lead wire 39 is not twisted and the exhaust gas sensor S is easily attached and wired. . Further, the connection portion formed by the connection terminal 32 and the terminal pin 26 is protected by the fitting cylinder 31 of the connector 30, and even if a stone flies away due to traveling of the vehicle or the like, the connection portion is not directly damaged and is shock-resistant. In addition, the fitting cylinder 31 can maintain the watertightness of the inside of the connector 30, and the water can prevent corrosion, short-circuiting or disconnection of the connection portion.

[Brief description of drawings]

FIG. 1 is a side view in which an exhaust gas sensor S and a connector 30 of a first embodiment are separated.

FIG. 2 is a vertical sectional side view of an assembled state of the first embodiment.

FIG. 3 is an exploded perspective view of a gas detection element body 20.

FIG. 4 is a side view of an exhaust gas sensor S of a second embodiment.

FIG. 5 is a vertical cross-sectional side view of an assembled state of the second embodiment.

FIG. 6 is a side view of an exhaust gas sensor S of a reference example .

FIG. 7 is a vertical cross-sectional side view of an assembled state of the reference example .

FIG. 8 is a vertical sectional side view of a conventional configuration.

FIG. 9 is a vertical sectional side view of the improved product.

[Explanation of symbols]

S exhaust gas sensor 1 Base metal fittings 2 Rotating operation part 3 male thread 4 connection 5 Engagement protrusion 10 outer cylinder 11 Connector mounting port 14 Protective tube 20 Gas detection element body 26 terminal pins 27 Insulation protection layer 30 connectors 31 Fitting tube 33 Holding member 36 Locking edge 40 male screw 41 female screw 42 Shutdown Tsuba 50 male screw 51 female screw

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-331597 (JP, A) JP-A-5-331596 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 27/409 G01N 27/12

Claims (2)

(57) [Claims] 1. A gas detecting element body is disposed by being held by an insulating protective layer inside a tubular body formed by connecting an outer cylinder to a rear end portion of a tubular base metal member, and the detecting portion at the tip thereof is insulated. In the exhaust gas sensor exposed to the front from the protective layer and used as the detection end, the inside of the rear end of the outer cylinder is the connector mounting opening that opens outward.
A terminal pin that is electrically connected to a required electric circuit of the gas detection element body is implanted in the insulating protective layer, the terminal pin is projected from the insulating protective layer into the connector mounting port, and the connector mounting port of the outer cylinder is provided. A connector which holds a connection terminal connected to a lead wire in a heavenly fitting tube to be fitted to the outside and draws the lead wire to the outside in a liquid-tight manner from the ceiling part of the fitting tube, With the connector fitted externally to the connector mounting port, the connection terminal is connected to a terminal pin, and an engaging protrusion is provided around the rear end of the tubular base metal fitting, and the fitting tube of the connector is mounted. A lead wire connecting mechanism for an exhaust gas sensor, characterized in that an engaging projection edge that engages with the engaging projection is formed at the tip of the inward projection . 2. A gas detecting element body is arranged and held by an insulating protective layer inside a tubular body formed by connecting an outer cylinder to the rear end portion of the tubular base metal member, and the detecting portion at the tip thereof is insulated. In the exhaust gas sensor exposed to the front from the protective layer and used as the detection end, the inside of the rear end of the outer cylinder is the connector mounting opening that opens outward.
A terminal pin that is electrically connected to a required electric circuit of the gas detection element body is implanted in the insulating protective layer, the terminal pin is projected from the insulating protective layer into the connector mounting port, and the connector mounting port of the outer cylinder is provided. A connector which holds a connection terminal connected to a lead wire in a heavenly fitting tube to be fitted to the outside and draws the lead wire to the outside in a liquid-tight manner from the ceiling part of the fitting tube, In a state where the connector is externally fitted to the connector mounting port, the connection terminal is connected to a terminal pin, and a male screw is formed on a peripheral surface of the tubular base metal fitting, and a lower end of a fitting cylinder of the connector is provided. A lead wire connecting mechanism for an exhaust gas sensor, characterized in that a female screw threaded to the male screw thread is provided on the circumference.