Electricity: electrical systems and devices – Safety and protection of systems and devices – Circuit interruption by thermal sensing
Reexamination Certificate
2000-07-07
2002-05-07
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Circuit interruption by thermal sensing
C361S106000
Reexamination Certificate
active
06385026
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit breaker for interrupting an electric circuit for a short time.
2. Description of the Related Art
In an electrical component system provided in a vehicle, when something is wrong with a load of a power window, a wire harness, or the like, constituted by a plurality of electric wires connecting a battery and various loads, a high-current fuse inserted between the battery and the wire harness is blown out to interrupt a connection between the battery and the wire harness, thereby preventing the loads, the wire harness, and the like from being burnt and damaged.
However, in the case of the electric component system using such a high-current fuse, even if something is wrong with the load of the power window, the wire harness, or the like connecting the battery and various loads, the fuse does not blow out unless a current exceeds a tolerated value which is previously set for the high-current fuse. Therefore, various protecting apparatuses have been developed. When a high-current close to the tolerated value is continuously flowing, the protecting apparatus detects the current and interrupts the connection between the battery and the wire harness.
FIG. 1
is a sectional view showing one example of the protecting apparatus using a bimetal. The protecting apparatus shown in
FIG. 1
is made of insulation resin, and comprises a housing
103
formed at its upper portion with a fuse accommodating portion
102
, a lid
113
for closing the fuse accommodating portion
102
such that the latter can be opened and closed, a power source terminal
105
disposed in a lower portion in the housing
103
such that an upper end of the power source terminal
105
projects into the fuse accommodating portion
102
and a lower end thereof is exposed outside, and the exposed portion of the power source terminal
105
being connected to a positive terminal of a battery
104
, a load terminal
109
disposed in a lower portion in the housing
103
such that an upper end of the load terminal
109
projects into the fuse accommodating portion
102
and a lower end thereof is exposed outside, and the exposed portion of the load terminal
109
being connected to a load
108
through an electric wire
107
constituting a wire harness
106
, a fusible member
110
made of low-melting metal and having one end connected to an upper end of the power source terminal
105
and the other end connected to an upper end of the load terminal
109
, an intermediate terminal
111
disposed in a lower portion in the housing
103
such that the intermediate terminal
111
is located at an intermediate position between the power source terminal
105
and the load terminal
109
and a lower end of the intermediate terminal
111
is exposed outside, and the exposed portion being connected to a negative terminal of the battery
104
, and a bimetal
112
which is made of a long plate-like member comprising two kinds of metal bonded together and which is disposed such as to be opposed to the fusible member
110
such that a lower end of the bimetal
112
is connected to an upper end of the intermediate terminal Ill and an upper end thereof being bent into an L-shape.
When an ignition switch and the like of the vehicle are operated, and a current is flowing through a path comprising the positive terminal of the battery
104
, the power source terminal
105
, the fusible member
110
, the load terminal
109
, the electric wire
107
of the wire harness
106
, the load
108
, and the negative terminal of the battery
104
, and when an abnormal condition occurs in the load
108
or in the wire harness
106
connecting the load
108
and a protecting apparatus
101
, and a current equal to or greater than the tolerated value flows through the fusible member
110
, the fusible member
110
is heated and blown out for protecting the load
108
, the wire harness
106
and the like.
Further, even if something is wrong with the load
108
or the wire harness
106
connecting the load
108
and the protecting apparatus
101
, and a large current flows through the fusible member
110
, if the current does not exceed the tolerated value, the fusible member
110
is heated by the current flowing through the latter and the bimetal
112
starts deforming. When a predetermined time is elapsed from the instance when the large current starts flowing through the fusible member
110
, a tip end of the bimetal
112
comes into contact with the fusible member
110
, and a large short-circuit current flows through the fusible member
110
in a path comprising the positive terminal of the battery
104
, the power source terminal
105
, the fusible member
110
, the intermediate terminal
111
, and the negative terminal of the battery
104
, and the latter is blown out.
With the above structure, even when a current equal to or lower than the tolerated value flows for a preset time or longer, the circuit is interrupted to protect the wire harness
106
and the load
108
.
As another protecting apparatus
101
rather than this protecting apparatus, a protecting apparatus
121
has also developed.
The protecting apparatus
121
shown in
FIG. 2
comprises a housing
122
made of insulation resin, a power source terminal
124
embedded in one side surface of the housing
122
and having a lower end connected to a positive terminal of a battery
123
, and a load terminal
128
embedded in the other side surface of the housing
122
and having a lower end connected to a load
127
through an electric wire
126
constituting a wire harness
125
. The protecting apparatus
121
further comprises an electric wire
131
including a fusible lead
129
which is made of low-melting metal and formed into U-shape and a heat-proof coating
130
formed such as to cover the fusible lead
129
. The protecting apparatus
121
further comprises a coil
132
. The coil
132
is made of shape-memory alloy which is formed into a shape wound around the electric wire
131
as shown in
FIG. 2
when it is in a martensite phase state, and which is formed into its original phase shape fastening the electric wire
131
. The protecting apparatus
121
further comprises an external terminal
133
whose upper end is connected to one end of the coil
132
and whose lower end is connected to a negative terminal of the battery
123
.
When an ignition switch and the like of the vehicle are operated, and a current is flowing through a path comprising the positive terminal of the battery
123
, the power source terminal
124
, the fusible lead
129
of the electric wire
131
, the load terminal
128
, the electric wire
126
of the wire harness
125
, the load
127
and the negative terminal of the battery
123
, and when an abnormal condition occurs in the load
127
or in the wire harness
125
connecting the load
127
and a protecting apparatus
121
, and a current equal to or greater than the tolerated value flows through the fusible lead
129
, the fusible lead
129
is heated and blown out for protecting the load
127
, the wire harness
125
and the like.
Further, even if something is wrong with the load
127
or the wire harness
125
connecting the load
127
and the protecting apparatus
121
, and a large current flows through the fusible lead
129
, if the current does not exceed the tolerated value, the fusible lead
129
is heated by the current flowing through the latter and a temperature of the coil
132
rises. When a predetermined time is elapsed from the instant when the large current starts flowing through the fusible lead
129
, and the temperature of the coil
132
rises to 120° C. to 170° C., the coil
132
changes from its martensite phase state to its original phase and bites into the heat-proof coating
130
which is softened by heat and comes into contact with the fusible lead
129
, and a large short-circuit current flows through the fusible lead
129
in a path comprising the positive terminal of the battery
123
, the power source terminal
124
, the fusible lead
129
,
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Jackson Stephen W.
Yazaki -Corporation
LandOfFree
Circuit breaker does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit breaker, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit breaker will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2820939