Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-01-03
2001-10-16
Warden, Sr., Robert J. (Department: 1744)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S279000, C204S297010, C029S592100, C029S595000
Reexamination Certificate
active
06303013
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a gas sensor installed in an exhaust system of an automotive internal combustion engine for measuring a specific gas concentration in exhaust gas or the like.
2. Description of the Related Art
A gas sensor installed in an exhaust system such as an exhaust manifold or an exhaust gas pipe of an automotive combustion engine is required to have durability to harsh environment such as high temperature and hard vibration. Parts for making up the gas sensor are therefore fixed to one another by caulking and welding, because fastening with screws is insufficient to fix the parts.
The caulking fixation is processing accompanied by plastic deformation. It is known that when a processing load (caulking load) is relieved after the caulking fixation is performed, a spring-back action readily occurs to prevent a caulked fixation portion, which is fixed by caulking, from having a sufficient fastening strength. Therefore, in the caulking fixation, hot-caulking is performed after performing cold-caulking.
FIG. 8
shows a typical structure of a gas sensor
9
. The gas sensor
9
is composed of a housing
2
having an insertion hole
29
into which a detection element
3
is inserted, a measurement gas side cover
111
fixed to an end portion of the housing
2
, and an air side cover
121
fixed to the other end portion of the housing
2
. A space defined by the detection element
3
in the insertion hole
29
is filled with powdery sealing material
132
. The powdery sealing material
132
is pushed by a metallic ring
134
, which is fixed to a caulked fixation portion
91
by caulking, through an insulating member
133
, and the like. In the caulking fixation, specifically, the caulked fixation portion
91
is bent by caulking to hold the metallic ring
134
, thereby fixing the metallic ring
134
.
FIG. 9
shows the caulked fixation portion
91
before it is caulked. The caulked fixation portion
91
is integrally formed with a body portion
90
of the housing
2
, and is composed of a buckling portion
911
, a thick portion
913
, and a caulked portion
912
provided in this order from the housing body portion
90
. The caulked fixation portion
91
is caulked by cold-caulking and hot-caulking as described above, so that the detection element
3
is fixed by pressure via the metallic ring
134
, the insulating member
133
, and the powdery sealing material
132
.
The thick portion
913
of the caulked fixation portion
91
is provided so that the deformation of the caulked portion is securely performed by caulking and so that the buckling portion is easily buckled. However, the thick portion
913
increases the weight of the housing
2
, and increases the size of the gas sensor
9
. The increases in size and weight are opposed to recent requirements to parts for the engine. To comply with strengthened exhaust gas regulations, every part for the engine is required to have a reduced size and a reduced weight to thereby reduce a load to the engine. The caulked fixation portion is therefore required to have a structure capable of securely performing the caulking fixation without having the thick portion. Lightening the gas sensor can additionally produce a material cost reduction.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above limitations. An object of the present invention is to provide a gas sensor with a reduced size and a reduced weight, at a low material cost.
According to the present invention, a gas sensor has a caulked fixation portion integrated with a housing, for fixing a detection element in an insertion hole of the housing, by caulking. The caulked fixation portion has a caulked portion for imparting a caulking force to a sealing member directly, and a buckling portion provided at a housing side of the caulked portion for increasing the caulking force by buckling in an axial direction of the housing.
The caulked fixation portion before caulked satisfies dimensional relationships of T
1
<T
3
<T
2
; 2<T
2
/T
1
; and 3<L/{(T
1
+T
2
)/2}. T
1
is a minimum thickness of the caulked portion in a radial direction of the housing, and T
2
is a maximum thickness of the caulked portion in the radial direction. T
3
is an average thickness of the buckling portion in the radial direction, and L is a length of the caulked portion in the axial direction. The caulked fixation portion does not have a thick portion.
Accordingly, the gas sensor of the present invention can be provided with a reduced size and a reduced weight of the housing at low material cost. Because the caulked fixation portion before caulked satisfies the dimensional relationships described above, S-like buckling is not produced at the caulked fixation portion. Therefore, a cover can securely fixed to the housing. This also contributes the size reduction of the gas sensor.
REFERENCES:
patent: 4705915 (1987-11-01), Van Brunt et al.
patent: 5135264 (1992-08-01), Elliot-Moore
patent: 5830339 (1998-11-01), Watanabe et al.
patent: 5859361 (1999-01-01), Fukaya et al.
patent: 5874663 (1999-02-01), Fukaya et al.
patent: 2-147817 (1990-06-01), None
patent: 8-160002 (1996-06-01), None
Kojima Takashi
Watanabe Isao
Denso Corporation
Olsen Kaj K.
Pillsbury & Winthrop LLP
Warden, Sr. Robert J.
LandOfFree
Gas sensor including caulked fixation portion for fixing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas sensor including caulked fixation portion for fixing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas sensor including caulked fixation portion for fixing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2612673