Pressure sensor constructed by joining two housings with...

Measuring and testing – Fluid pressure gauge – Mounting and connection

Reexamination Certificate

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Reexamination Certificate

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06564645

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure sensor to be assembled by mutually engaging a sensor housing formed of metal, and a connector housing mainly formed of synthetic resin.
2. Discussion of the Related Art
One example of such a pressure sensor mentioned above, disclosed in Japanese Patent Application Laid-Open Publication No. 209115/1995, titled “SEMI-CONDUCTOR TYPE PRESSURE SENSOR AND MANUFACTURING METHOD THEREFOR,” is generally known.
Referring to
FIG. 10
, there is shown a section of a pressure sensor
900
constructed according to the conventional technology described in the above publication. As shown in
FIG. 10
, the conventional technology permits the pressure sensor
900
to be assembled by effecting so called caulking (i.e., curling) directly on a connector housing
1
(formed of synthetic resin) in which terminal pins
2
a,
2
b
and the like have been insert-molded. The caulking is performed by curling a projecting portion or one of two end portions of a sensor housing
3
(formed of metal), resulting in juncture and fixed engagement of the connector and sensor housing
1
,
3
.
However, the conventional pressure sensor, which is to be assembled by the caulking performed directly on the connector housing
1
, suffers from the following problems:
(Problem1)
When the caulking is performed for assembling the pressure sensor
900
, the junction of the connector housing
1
formed of synthetic resin and the sensor housing
1
, which junction means an abutment surface of the connector housing
1
on which the projecting portion or the one end portion of the connector housing
3
abuts, is subjected to an excessively large stress thereon, leading to a likelihood of undesired deformation or failure of the connector housing
1
.
(Problem 2)
Since the connector housing
1
confines a fluid
13
of high-pressure in a fluid-tight manner, the junction of connector housing
1
with the sensor housing
3
is, in operation of the pressure sensor
900
, subjected to a large compressive stress thereon, unexpectedly resulting in deformation or deflection of the connector housing
1
at the above junction thereof.
One of possible solutions to those problems is, for instance, to design the connector housing
1
so as to have an increased area for the junction of the connector housing
1
. However, this solution would increase the total size of a pressure sensor, meaning that downsizing thereof would be prevented.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a pressure sensor which is available even under high pressure and which is capable of being downsized.
This object indicated above may be achieved according to any one of the following modes of this invention. Each of these modes of the invention is numbered like the appended claims, and depends from the other mode or modes, where appropriate. This type of explanation about the present invention is for better understanding of some ones of a plurality of technical feats and a plurality of combinations thereof disclosed in this specification, and dose not mean that the plurality of technical features and the plurality of combinations in this specification are interpreted to encompass only the following modes of this invention:
(1) A pressure sensor including a sensor housing formed of metal, and a connector housing mainly formed of synthetic resin. The connector housing includes a shoulder portion thereof in the form of a metal plate having an inner and an outer periphery thereof, on which shoulder portion a juncture of the sensor and connector housing is formed as a result of joining the sensor and connector housing by curling a projecting portion or one of two end portions of the sensor housing toward the shoulder portion. Further, the curling is performed under engagement of the sensor and connector housing therebetween, for assembling the pressure sensor.
In the pressure sensor according to this mode (1), the shoulder portion of the connector housing functioning as the junction of the connector housing with the sensor housing is constructed by the metal plate. As a result, the strength of pressure resistance of the pressure sensor is increased, preventing the connector housing from being unexpectedly deformed or failed when manufactured. The increase in the strength of pressure resistance of the pressure sensor would also eliminate a likelihood of undesired deformation and deflection of the connector housing, leading to availability of the pressure sensor even in high-pressure environment.
In the pressure sensor according to this mode (1), the term “connector housing” may be interpreted to mean a sub-housing of the pressure sensor for accommodating at least one external connector, and the term “sensor housing” may be interpreted to mean another sub-housing of the pressure sensor for receiving a fluid, a pressure of which is to be measured by the pressure sensor. It is not indispensable in practicing the present invention, to configure the sensor housing to accommodate a pressure-sensitive element
In the pressure sensor according to this mode (1), the term “inner periphery of the metal plate” can be called a “through hole” for permitting a terminal pin to be passed therethrough.
(2) The pressure sensor according to the above mode (1), wherein the metal plate is generally shaped as a ring.
(3) The pressure sensor according to the above mode (1) or (2), wherein the sensor housing is coaxially fitted with the connector housing, wherein the metal plate includes one reference line intersecting a plane of the metal plate, and wherein the metal plate is fitted with the connector housing such that the connector housing extends substantially parallel to the reference line.
(4) The pressure sensor according to any one of the above modes (1)-(3), wherein the junction of the sensor and connector housing is located on an edge of the shoulder portion of the connector housing, which edge is formed so as to include, on a cross-section obtained by hypothetically cutting the shoulder portion by a reference plane perpendicular to a plane of the metal plate, at least one of a curved line, a straight line intersecting the plane of the metal plate, and a stepped line.
The pressure sensor according to this mode (4) would enable an area of a surface on which a contact of the shoulder portion of the connector with the sensor housing is performed, to be easily increased as compared with the case of a metal plate having a flat end face thereof. The increase in the contacting area contributes to even distribution of pressures acting on a portion of the connector housing which is contacted with one of two end faces of the metal plate, meaning that the strength of pressure resistance of the pressure sensor is improved.
(5) The pressure sensor according to any one of the above modes (1)-(4), wherein the connector housing is integrally formed together with the metal plate.
The pressure sensor according to this mode (5) would permit a reduction in the manufacturing time thereof, and would also permit close engagement between the metal plate and the remainder of the connector housing which is formed of synthetic resin. The close engagement between the metal plate and the remainder of the connector housing would, for example, facilitate to downsize the pressure sensor, and to increase the strength of the pressure resistance of the pressure sensor.
(6) The pressure sensor according to the above mode (5), wherein the connector housing is formed by a process in which the metal plate is inserted into a mold for molding the connector housing, prior to the molding, and then a mass of raw synthetic resin is fed into the mold and is thereafter hardened.
(7) The pressure sensor according to any one of the above modes (1)-(6), wherein the metal plate is fitted with the connector housing unremovably therefrom, by holing the metal plate by two opposing portions of the connector housing which cooperate to cause the metal plate to be interposed therebetween.
(8) The pres

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