Electricity: circuit makers and breakers – Special application – Change of inclination or of rate of motion responsive
Reexamination Certificate
2002-04-19
2003-11-04
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Special application
Change of inclination or of rate of motion responsive
C200S061440, C200S061460, C200S061480, C200S061490, C200S061520, C200S061510
Reexamination Certificate
active
06642461
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims benefit of priority of Japanese Patent Application No. 2001-199397 filed on Jun. 29, 2001, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a detector for detecting a deceleration impact exceeding a predetermined level caused by an accidental collision or the like. The detector is used, for example, to generate a signal for inflating an air-bag mounted on an automotive vehicle.
2. Description of Related Art
A conventional collision detector is disclosed, for example, in JP-A-2000-182488. The collision detector disclosed in this publication, as shown in
FIG. 10
, is composed of a rotor
110
rotatably supported by a rotor shaft
100
, a cam
120
fixed to the rotor
110
, a pair of contact springs
130
,
140
which are closed by the cam
120
when the rotor
110
rotates by a predetermined rotational angle, and a printed circuit board
150
having an electrical circuit for generating a signal upon closing of the pair of contact springs
130
,
140
.
Referring to
FIGS. 11 and 12
, operation of this collision detector will be explained. When a deceleration is caused by a vehicle collision, the rotor
110
rotates in a direction shown by “b” against a biasing force Tset (in a direction shown by “a”) of a contact spring
130
. The contact spring
130
is pushed by the cam
120
rotating together with the rotor
110
and is resiliently deformed thereby to contact the other contact spring
140
. Upon closing of the contact springs
130
,
140
, an electrical signal (an ON signal) for inflating an air-bag is generated.
However, there are following problems in this collision detector. (1) After the contact spring
130
contacts the other contact spring
140
, the other contact spring
140
resonantly vibrates due to a collision impact, and thereby a contact between two contact springs
130
,
140
cannot be maintained. Accordingly, a stable and reliable signal is not obtained form the collision detector. (2) Since the contact spring
130
biases the rotor
110
toward its initial position, an abrasion torque is always applied to the rotor
110
. A dispersion of the abrasion torque causes a functional dispersion of the collision detector. (3) The contact spring
130
contacts the other contact spring
140
at a rotational angle, i.e., at an ON position shown in FIG.
12
. Since after the ON position, the resilient force of the contact spring
140
is additionally applied to the rotor
110
, a value Tset/MR (Tset is a biasing force in the direction “a” and MR is a rotational moment of the rotor in a direction “b”) rapidly increases. Therefore, it is difficult to maintain the ON signal for a long time. (4) Since a housing base
170
is connected to a housing
160
supporting the rotor shaft
100
, as shown in
FIG. 11
, a dimensional dispersion in connecting the housing base
170
to the housing
160
causes a dispersion in function of the collision detector. (5) A rotor assembly mounted on the housing
160
is inserted into an inside space of a casing
180
, and a gap between the housing
160
and the casing
180
has to be sealed. If a sealing material is supplied into the gap, it leaks into the casing
180
. Therefore, instead of using the sealing material, a packing
190
covering the bottom end of the casing
180
is disposed to provide a hermetical sealing, as shown in FIG.
10
. Further, a lid
200
covering the packing
190
is connected to the bottom end of the casing
180
by heat-staking the bottom end. Use of the packing
190
and performing the heat-staking require an additional manufacturing cost.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an improved deceleration impact detector which functions with a high stability and reliability and can be manufactured at a low cost.
The deceleration impact detector is used for detecting a high deceleration generated by an accidental collision of a vehicle or the like. An air-bag for protecting a passenger is inflated upon receipt of an electrical signal from the deceleration impact detector. The deceleration impact detector includes a rotor having its gravity center eccentric relative to a rotational center of the rotor, a coil spring biasing the rotor to its initial position, a cam connected to the rotor, and a contact member consisting of a resiliently movable contact and a stationary contact. When a deceleration exceeding a predetermined level is imposed on the rotor, the rotor rotates so that the cam connected to the rotor pushes the movable contact thereby to close the contact member. Upon closing the contact member, the detector generates an ON signal for operating the air-bag.
The movable contact is made of a resilient leaf spring and the stationary contact is made of a plate having a high rigidity, thereby to avoid resonant vibrations of the stationary contact upon receipt of a high deceleration impact. The movable contact is positioned apart from the cam, forming a certain space therebetween, when the rotor is at its initial position. In this manner, rotation of the rotor is not restricted by the resilient force of the movable contact.
The cam includes a first surface for pushing the movable contact and a second surface continuing from the first surface. The second cam surface is formed in a circular curvature around the rotational center of the rotor, so that the movable contact is not further pushed according to the rotation of the rotor after the contact member is closed. The electrical ON signal is maintained by the second cam surface while avoiding the resilient force of the movable contact from being applied to the rotor.
Components of the detector including the rotor, the coil spring and the contact member are mounted on a housing having a rectangular housing base. The rectangular housing base is press-fitted into a rectangular opening of a casing thereby to contain the housing in the casing. Flanges extending from the four corners of the housing base are formed, so that the flanges are tightly received on receiving surfaces formed at corners of the casing. The housing base and the casing are hermetically sealed with a filler material filling small spaces between the housing base and the casing. The housing base may be separated into two parts, a base frame and a base plate press-fitted into the base frame, both parts being connected by crank-shaped connecting pins formed by molding.
According to the present invention, the deceleration impact detector stably functioning with a high reliability and having a simple structure is manufactured at a low cost.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings.
REFERENCES:
patent: 5898144 (1999-04-01), Sakai et al.
patent: 6093897 (2000-07-01), Inoue et al.
patent: 6172313 (2001-01-01), Sakamoto et al.
patent: 1 103 816 (2001-05-01), None
patent: 1 103 816 (2001-05-01), None
patent: A 2000-182488 (2000-06-01), None
Denso Corporation
Enad Elvin
Oliff & Berridg,e PLC
Poker Jennifer A.
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