Information
-
Patent Grant
-
6411190
-
Patent Number
6,411,190
-
Date Filed
Wednesday, August 2, 200023 years ago
-
Date Issued
Tuesday, June 25, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Finnegan, Henderson, Farabow, Garrett & Dunner, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 337 401
- 337 157
- 337 408
- 337 409
- 307 119
- 180 271
- 180 274
- 180 279
- 200 6108
- 361 115
-
International Classifications
- H01H7120
- H01H3776
- B60L100
- B60K2810
-
Abstract
A current sensor 73 detects a current flowing through a first buss bar 11. When a current value detected by the current sensor 73 became equal to or greater than a threshold current value, a CPU 74 outputs a driving control signal to a driving circuit 77, and the driving circuit 77 operates an, ignitor 29 through a second substrate 65 and a terminal 50. Therefore, the ignitor 29 ignites, a second projection 41 is melted by heat of a heating agent 27, a compression spring 34 is expanded and a thermite case 26 jumps up. Thus, electrical connection between the thermite case 26 and the first and second buss bars 11, 19 is interrupted. Further, since an outer container 61 in which the current sensor 73, the CPU and the driving circuit 77 are accommodated is integrally assembled with the cap 14a and the resin case 14b in which the thermite case 26, the ignitor 29, the compression spring 34 and the second projection 41 are accommodated, non-operational state of the ignitor 29 due to disconnection of electric wire is not generated.
Description
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, and more particularly, to a circuit breaker integrally provided with a breaker portion for interrupting an electric circuit and a control portion for controlling the breaker portion.
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 or the like, or when something is wrong with a wire harness or the like constituted by a plurality of electric wires connecting a battery and various loads to each other, 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 or the like, or something is wrong with the wire harness or the like connecting the battery and various loads, the fuse is not blown out unless a current equal to or greater than a tolerated value which is previously set for the high-current fuse. Therefore, various protecting apparatuses have been developed for detecting the current and interrupt the connection between the battery and the wire harness when a high current close to the tolerated value is continuously flowing.
FIG. 1
is a sectional view showing one example of the protecting apparatus using a bimetal (Japanese Utility Model Application Laid-open No. S64-29756). 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 disposed in the fuse accommodating portion
102
, 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
111
and an upper end thereof being bent into an L-shape.
When an ignitor 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 following through the latter, and the bimetal
112
starts deforming. When a predetermined time is elapsed from the instant 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 investigated by the present inventors rather than this protecting apparatus
101
, a protecting apparatus
121
shown in
FIG. 2
has been also developed (Japanese Utility Model Application Laid-open No. S64-29756).
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 returned to its original phase shape fastening the electric wire
131
when it is heated from 120° C. to 170° C. 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 ignitor 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
, the coil
132
, the external terminal
133
, and the negative terminal of the battery
123
, 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
125
and the load
127
.
However, in the above-described conventional protecting apparatuses
101
and
121
, there are problems as follows.
First, in the case of the protecting apparatus shown in
FIG. 1
, it is detected whether a large current flows through the fusible member
110
using the bimetal
112
made of two kinds of metals having different thermal expansion coefficients and bonded to each other. Therefore, if the magnitude of the current is flowing through the fusible member
110
, the bimetal
112
is deformed, and the time that elapsed before the circuit is interrupted is varied, depending on the current flowing therethrough.
Thus, when a failure that a large current flows intermittently occurs, a temperature of the fusible member
110
does not rise more than a certain value, and there is an adverse possibility that the wire harness
106
or the load
108
may be burnt before the protecting apparatus
101
interrupts the circuit.
In the case of the protecting apparatus
121
shown in
FIG. 2
, it is detected whether a large current flows through the fusible lead
129
using the coil
132
made of shape-memory alloy. Therefore, if the magnitude of the current is flowing through the fusible lead
129
, the coil
132
is deformed, and the time that elapsed before the circuit is interrupted is varied—depending upon the flowing current.
Thus, when a failure that a large current flows intermittently occurs, a temperature of the fusible lead
129
does not rise more than a certain value, and there is an adverse possibility that the wire harness
125
or the load
127
may be heated excessively before the protecting apparatus
121
interrupts the circuit. Further, if the bimetal or shape-memory alloy is used, since the deformation-starting temperature is usually as low as about 100° C., it is difficult to use it at 120° C. to 125° C. which is the using environment temperature condition of the vehicle.
Further, in the protecting apparatuses shown in
FIGS. 1 and 2
, the heat reaction time of the bimetal
112
or of the coil
132
which is a thermal-deformable electrical conduction member is varied depending upon the current flowing therethrough. Further, the heat reaction of the thermal-deformable electrical conduction member is not operated timely in some cases when an abnormal condition occurs (when excessive current flows).
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a circuit breaker capable of reliably interrupting a circuit in a short time to protect an electrical part when an abnormal signal of a vehicle is inputed.
To achieve the above object, according to a first aspect of the present invention, there is provided a circuit breaker comprising a conductive heating portion disposed between a first connecting terminal and a second connecting terminal such that the heating portion is in contact with the first connecting terminal and the second connecting terminal and having a heating agent therein, an ignitor accommodated in the heating portion for igniting the heating agent charged in the heating portion when abnormal conditions of a vehicle are encountered, an expandable resilient member which is disposed such that the resilient member is in contact with the heating portion for pushing the heating portion, a melting member for maintaining the resilient member in its compressed state, a first container for accommodating the heating portion, the ignitor, the resilient member and the melting member, a detecting portion for detecting an abnormality of the vehicle, a judging portion for judging whether the vehicle is under abnormal conditions based on an output from the detecting portion and for outputting a driving control signal when the judging portion judged that the vehicle is under the abnormal conditions, a driving portion for operating the ignitor based on the driving control signal from the judging portion, and a second container for accommodating the detecting portion, the judging portion and the driving portion, and the second container being integrally assembled with the first container.
According to the first aspect, if the detecting portion detects an abnormality of the vehicle, the judging portion judges whether the vehicle is under the abnormal conditions based on the output from the detecting portion, and if the judging portion judged that the vehicle is under the abnormal conditions, the judging means output the driving control signal, and the driving portion operates the ignitor based on the driving control signal from the judging portion. Therefore, the ignitor ignites the heating agent charged in the heating portion, the melting member is melted by the heat of the heating agent, the compressed resilient member is expanded and the heating portion jumps up. Therefore, the electrical connection between the heating portion and the first and second connecting terminals is cut off, and the circuit can be interrupted.
Accordingly, since the second container accommodating the detecting portion, the judging portion and the driving portion, and the second container being integrally assembled with the first container accommodating the heating portion, the ignitor, the resilient member and the melting member, a non-operational state of the ignitor due to disconnection of electric wire is eliminated.
According to a second aspect of the invention, in the circuit breaker of the first aspect, the circuit breaker further comprises a connector having a terminator whose one end is electrically connected to the ignitor, and a substrate provided for mounting the detecting portion, the judging portion and the driving portion into the second container, and the other end of the terminal is soldered to the substrate, and the driving portion and the ignitor are electrically connected to each other through the substrate and the terminal.
According to the second aspect, the one end of the terminal of the connector is electrically connected to the ignitor, the other end of the terminal is soldered to the substrate on which the driving portion is mounted, and the driving portion and the ignitor are electrically connected to each other through the substrate and the terminal. Therefore, there is no connection using electric wire and thus, an adverse possibility that the ignitor
29
is erroneously operated due to noise is reduced.
According to a third aspect of the invention, in the circuit breaker of the second aspect, the connector is detachable with respect to the ignitor, and the connector is disengaged from the ignitor when the ignitor is moved by ignition of the heating agent.
According to the third aspect, when the ignitor is pushed upward and moved by ignition of the heating agent, the connector is disengaged from the ignitor, and the power supply to the ignitor can be automatically stopped. With this structure, the current does not keep flowing, heat is not transmitted to the substrate and the like and thus, the electronic such as the substrate and device is less prone to be damaged.
According to a fourth aspect of the invention, in the circuit breaker of the first aspect, the detecting portion is a current sensor for detecting a current flowing through at least one of the first connecting terminal and the second connecting terminal, and the judging portion judges whether a current value detected by the current sensor became equal to or greater than a preset threshold value, and if the current value detected by the current sensor became equal to or greater than the threshold value, the judging portion outputs the driving control signal to the driving portion.
According to a fifth aspect of the invention, in the circuit breaker of the first aspect, the melting member is made of resin member which is formed in the first container and which prevents a pushing force of the resilient member against the heating portion.
According to the fifth aspect, since the melting member formed in the first container is made of resin member which prevents a pushing force of the resilient member against the heating portion, the resin member can be melted and the heating portion and the ignitor can be lifted up when the heating agent is ignited.
According to a sixth aspect of the invention, in the circuit breaker of the first aspect, an end of the heating portion is formed with a side wall, and the side wall is connected to the first connecting terminal and the second connecting terminal through a low-melting material.
According to the sixth aspect, since the side wall is connected to the first connecting terminal and the second connecting terminal through the low-melting material, if the resin member and the low-melting material are melted by the heat of the heating agent, the heating portion jumps up, the electrical connection between the first and second connecting terminals is cut off and therefore, the circuit can reliably be interrupted within a short time to protect an electric part. Further, since the spring force is not applied to the low-melting metal which connects the first and second connecting terminals and the heating portion, it is possible to enhance the reliability of the connected portion.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a sectional view showing one example of a conventional protecting apparatus using a bimetal;
FIG. 2
is a sectional view showing another example of the conventional protecting apparatus;
FIG. 3
is a sectional view of a circuit breaker of an embodiment taken along the line III—III in
FIG. 4
;
FIG. 4
is a top view of the circuit breaker of the embodiment;
FIG. 5
is a sectional view of the circuit breaker of the embodiment taken along the line V—V in
FIG. 4
; and
FIG. 6
is a block diagram of the circuit breaker of the embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
An embodiment of a circuit breaker of the present invention will be explained in detail with reference to the drawings.
The circuit breaker of the present embodiment is characterized in that a circuit from a battery to a load can be reliably interrupted within a short time when something is wrong with a vehicle, and the circuit breaker integrally provided with a breaker portion for interrupting the circuit and a control portion for controlling the breaker portion.
In the circuit breaker shown in
FIG. 3
, a plate-like long first bus bar
11
is made of copper or copper alloy for example, and is formed with a round hole
12
connected to a battery or the like. The first bus bar
11
is bent downward substantially at the right angle.
A plate-like long second bus bar
19
is also made of copper or copper alloy for example, and is formed with a round hole
20
connected to a load or the like. The second bus bar
19
is also bent downward substantially at the right angle.
A gap
14
a
and a resin case
14
b
are disposed between the first bus bar
11
and the second bus bar
19
. The gap
14
a
and the resin case
14
b
constitute a first container made of insulating material such as resin (thermoplastic resin).
A thermite case
26
made of copper, copper alloy or the like is accommodated in the resin case
14
b,
and a heating agent
27
is charged in the thermite case
26
, and an ignitor
29
is accommodated in the thermite case
26
.
The ignitor
29
includes an igniting agent which is ignited by heat generated by current flowing through a terminal
50
of a connector
45
when something is wrong with the vehicle, thereby allowing the heating agent
27
to generate a thermite reaction heat.
A left side wall formed on the thermite case
26
is connected to a bus bar tip end
13
through low-melting metal
23
as low-melting material such as solder (melting point is 200° C. to 300° C.) or the like. A right side wall formed on the thermite case
26
is connected to a bus bar tip end
21
through low-melting metal
23
. Therefore, the first bus bar
11
and the second bus bar
19
can be electrically connected to each other through the low-melting metal
23
and the thermite case
26
.
The low-melting metal
23
is made of at least one metal selected from Sn, Pb, Zn, Al and Cu.
The heating agent
27
is made of metal-oxide powder such as ferric oxide (Fe
2
O
3
) and aluminum powder, and is thermite agent which thermite-reacts by heat of the lead wire
31
to generate high heat. Chromic oxide (Cr
2
O
3
), manganese oxide (MnO
2
) or the like may be used instead of ferric oxide (Fe
2
O
3
).
The heating agent
27
may be made of mixture comprising at least one metal powder selected from B, Sn, Fe, Si, Zr, Ti and Al; at least one metal selected from CuO, MnO
2
, Pb
3
O
4
, PbO
2
, Fe
3
O
4
and Fe
2
O
3
; and at least one additive comprising alumina, bentonite and talc. Such a heating agent is easily is ignited by the ignitor
29
, and the low-melting metal
23
can be melted within a short time.
An expandable compression spring
34
is disposed as a resilient member between the thermite case
26
and the resin case
14
b,
and this compression spring
34
pushes the thermite case
26
upward.
As shown in
FIG. 5
, the cap
14
a
is formed with a groove
37
, and a first projection
39
formed on the resin case
14
b
is engaged with the groove
37
. The resin case
14
b
is formed with a second projection
41
made of resin which is melted by heat. The second projection
41
pushes an upper face of the thermite case
26
to prevent the thermite case
26
from moving upward by a spring force of the compression spring
34
.
A connector
45
having a terminal
50
is detachably mounted to the ignitor
29
. One end of the terminal
50
is connected to a heater (not shown) provided on the ignitor
29
, and the other end of the terminal
50
is soldered to a second substrate
65
. With this structure, the current from the second substrate
65
flows into the heater through the terminal
50
, and the ignitor
29
is operated by heat generated by the heater.
A pair of L-shaped and inverted L-shaped container-assembling ribs
62
are formed on the resin case
14
b.
An outer container
61
as a second container is assembled to the resin case
14
b
through the pair of container-assembling ribs
62
.
This outer container
61
accommodates a first substrate
63
disposed substantially in parallel to the left side wall of the resin case
14
b,
and a second substrate
65
disposed substantially vertically with respect to the first substrate
63
such that the second substrate
65
is opposed to a bottom face of the resin case
14
b.
The first substrate
63
is assembled to a substrate-assembling portion
64
which is formed in the outer container
61
, and comprises a current sensor
73
, a central processing unit (CPU)
74
, a driving circuit
77
and the like. The current sensor
73
comprises a magnetoelectric converting element and the like disposed in the vicinity of the first bus bar
11
for detecting a current flowing to the first bus bar
11
.
The outer container
61
is formed with projections
67
and
68
, and the second substrate
65
is screwed to the projection
68
by a screw
69
and fixed to the outer container
61
. The second substrate
65
is electrically connected to the first substrate
63
through a jumper wire
66
, and the other end of the terminal
50
of the connector
45
is soldered to the second substrate
65
. With this structure, a current is supplied from the driving circuit
77
of the first substrate
63
to the ignitor
29
through the second substrate
65
and the terminal
50
.
Next, details of the circuit structure in the outer container provided in the circuit breaker will be explained with reference to FIG.
6
. As shown in
FIG. 6
, the circuit breaker is provided between the battery
1
and the load
5
, and comprises a power source
70
having a voltage sensor
71
for detecting a voltage from the battery
1
, a sensor
72
having a current sensor
73
and a temperature sensor
74
, a judging portion
75
, the driving circuit
77
, a heater
79
, the igniting agent
82
which is ignited by heat of the heater
79
, the first bus bar
11
and the second bus bar
19
.
The power source
70
, the sensor
72
, the judging portion
75
and the driving circuit
77
are provided in the outer container
61
. The heater
79
, the igniting agent
82
, the first bus bar
11
and the second bus bar
19
are provided in the resin case
14
b.
The power source
70
is of 5V for example, opposite end voltages of the battery
1
are input to the power source
70
, and the power source
70
supplies voltage to the sensor
72
, the judging portion
75
and the driving circuit
77
. The current sensor
73
detects a current flowing through the load
5
, and is a Hall device or the like for converting a magnetic field generated by the current into an electric signal. The temperature sensor
74
is a thermistor for example for detecting a temperature by resistance varied by heat generated by the current.
The judging portion
75
comprises the CPU
74
, and judges whether a current value detected by the current sensor
73
becomes equal to or greater than a threshold current value. The driving circuit
77
includes a field-effect transistor (FET) or the like for example, and turns the heater
79
ON to allow a current to flow when the judging portion
75
judges that the current value detected by the current sensor
73
becomes equal to or greater than the threshold current value.
The judging portion
75
may turn the FET ON to allow a current to flow to the heater
79
when a temperature value detected by the temperature sensor
74
becomes equal to or greater than a threshold temperature, or may turn the FET ON to allow a current to flow to the heater
79
when a voltage value detected by the voltage sensor
71
becomes abnormal voltage value.
The igniting agent
82
is ignited by the heat of the heater
79
to interrupt the electrical connection between the first bus bar
11
and the second bus bar
19
to cut off the power source supply from the battery
1
to the load
5
.
Next, the operation of the circuit breaker of the present embodiment structured as described above will be explained with reference to the drawings.
First, under the normal condition, the first bus bar
11
and the second bus bar
19
are electrically connected to each other through the low-melting metal
23
and the thermite case
26
, and a current is supplied to the load (not shown) from the battery (not shown).
Next, if the current sensor
73
provided in the outer container
61
detects a current flowing through the first bus bar
11
, the judging portion
75
judges whether the current value detected by the current sensor
73
became equal to or greater than a preset threshold current value.
If the detected current value became equal to or greater than the threshold current value, the driving circuit
77
provided on the first substrate
63
allows a current to flow to the heater
79
of the ignitor
29
through the second substrate
65
and the terminal
50
. Then, the ignitor
29
is ignited by heat generated by the current and therefore, the heating agent
27
which is a thermite agent generates a thermite reaction heat according to the following reaction expression:
Fe
2
O
3
+2Al→Al
2
O
3
+2Fe+386.2 Kcal
The thermite case
26
is heated by the thermite reaction heat, the low-melting metals
23
connecting the bus bar tip end
13
and the left side wall of the thermite case
26
to each other, as well as the low-melting metal
23
connecting the bus bar tip end
21
and the right side wall of the thermite case
26
are heated and melted by heat of the heating agent
27
and the thermite case
26
. Simultaneously with this, the second projection
41
made of resin member formed on the resin case
14
b
is melted by the heat.
As a result, the compression spring
34
which had been compressed is expanded, and the thermite case
26
accommodating the ignitor
29
jumps upward (
26
′ in
FIG. 3
represents the thermite case after it moved upward).
Therefore, the electrical connection between the thermite case
26
, the first bus bar
11
and the second bus bar
19
is cut off. That is, the first bus bar
11
and the second bus bar
19
are electrically interrupted, and the electric circuit of the vehicle is interrupted.
When the ignitor
29
and the thermite case
26
jumped up, the connector
45
is disengaged from the ignitor
29
.
As described above, according to the circuit breaker of the present embodiment, it is possible to reliably interrupt the electric circuit of a vehicle within a short time to protect an electrical part.
Further, since the outer container
61
in which the current sensor
73
, the judging portion
75
and the driving circuit
77
are accommodated is integrally assembled with the cap
14
a
and the resin case
14
b
in which the thermite case
26
, the ignitor
29
, the compression spring
34
and the second projection
41
are accommodated, non-operational state of the ignitor
29
due to disconnection of electric wire from the driving circuit
77
is not generated.
Further, the one end of the terminal
50
is electrically connected to the ignitor
29
, the other end of the terminal
50
is soldered to the second substrate
65
and the driving circuit
77
and the ignitor
29
are electrically connected to each other through the second substrate
65
and the terminal
50
. Therefore, there is no connection using electric wire and thus, an adverse possibility that the ignitor
29
is erroneously operated due to noise is reduced.
Even if the number of circuit protecting portions is varied, it is possible to deal with a plurality of circuit protecting portions by commonly using the control portion without changing the control portion such as the current sensor
73
, the judging portion
75
and the driving circuit
77
included in the outer container
61
. Further, the breaker portion and the controlling portion are integrally formed, it is possible to simplify the wire harness and the connector constituting peripheral circuits of the circuit breaker.
Further, since the second projection
41
formed in the resin case
14
b
prevents the compression spring
34
from expanding upward, the spring force is not applied to the low-melting metal
23
which connects the first bus bar
11
, the second bus bar
19
and the thermite case
26
and thus, it is possible to enhance the reliability of the connected portion.
Furthermore, since the ignitor
29
is disengaged from the connector
45
and lifted up after ignitor, power supply to the ignitor
29
can automatically stopped. With this structure, the current does not keep flowing, heat is not transmitted to the substrate and the like and thus, the electronic such as the substrate and device is less prone to be damaged.
Further, since the cap
14
a
is put on the resin case
14
b,
the thermite case
26
will not jump out from the cap
14
a
when the circuit is interrupted, and this can prevent a burn caused by heat.
The, present invention is not limited to the circuit breaker of the above-described embodiment. Although the compression spring
34
and the low-melting metal
23
are provided, and the circuit is interrupted when the second projection
41
and the low-melting metal
23
are melted in the embodiment, only the second projection
41
may be provided without providing the low-melting metal
23
, and the circuit may be interrupted when the second projection
41
is melted.
In the circuit breaker of the embodiment, the second projection
41
formed on the resin case
14
b
pushes the upper face of the thermite case
26
, and the upward movement of the thermite case
26
by the spring force of the compression spring
34
is prevented.
For example, the thermite case
26
may be formed with a screw this screw may be threadedly engaged with another screw made of resin member as a melting member formed on the resin case
14
b,
and the upward movement of the thermite case
26
by the spring force of the compression spring
34
may be prevented by fixing the thermite case
26
to the resin case
14
b.
In this case, when the thermite case
26
is heated, the screw made of resin member formed on the resin case
14
b
is melted, the thermite case
26
is moved upward by the spring force of the compression spring
34
to interrupt the circuit.
Although the second projection
41
and the screw were indicated as the melting members, the melting members are not limited to those, and the melting member may be a resin member or a low-melting metal which maintains the compression spring
34
in its compressed state under a normal condition, and which is melted by heat when a circuit is to be interrupted. It is of course possible to make various modifications without departing from the spirit or scope of the invention.
Claims
- 1. A circuit breaker comprisinga conductive heating portion disposed between a first connecting terminal and a second connecting terminal such that the heating portion is in contact with the first connecting terminal and the second connecting terminal and having a heating agent therein, an ignitor accommodated in the heating portion for igniting the heating agent charged in the heating portion when abnormal conditions of a vehicle are encountered, an expandable resilient member which is disposed such that the resilient member is in contact with the heating portion for pushing the heating portion, a melting member for maintaining the resilient member in its compressed state, a first container for accommodating the heating portion, the ignitor, the resilient member and the melting member, a detecting portion for detecting an abnormality of the vehicle, a judging portion for judging whether the vehicle is under abnormal conditions based on an output from the detecting portion and for outputting a driving control signal when the judging portion judged that the vehicle is under the abnormal conditions, a driving portion for operating the ignitor based on the driving control signal from the judging portion, and a second container for accommodating the detecting portion, the judging portion and the driving portion, and the second container being integrally assembled with the first container.
- 2. A circuit breaker according to claim 1, further comprisinga connector having a terminator whose one end is electrically connected to the ignitor, and a substrate provided for mounting the detecting portion, the judging portion and the driving portion into the second container, wherein the other end of the terminal is soldered to the substrate, and the driving portion and the ignitor are electrically connected to each other through the substrate and the terminal.
- 3. A circuit breaker according to claim 2, wherein the connector is detachable with respect to the ignitor, and the connector is disengaged from the ignitor when the ignitor is moved by ignition of the heating agent.
- 4. A circuit breaker according to claim 1, whereinthe detecting portion is a current sensor for detecting a current flowing through at least one of the first connecting terminal and the second connecting terminal, and the judging portion judges whether a current value detected by the current sensor became equal to or greater than a preset threshold value, and if the current value detected by the current sensor became equal to or greater than the threshold value, the judging portion outputs the driving control signal to the driving portion.
- 5. A circuit breaker according to claim 1, whereinthe melting member is made of resin member which is formed in the first container and which prevents a pushing force of the resilient member against the heating portion.
- 6. A circuit breaker according to claim 1, whereinan end of the heating portion is formed with a side wall, and the side wall is connected to the first connecting terminal and the second connecting terminal through a low-melting material.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-220340 |
Aug 1999 |
JP |
|
US Referenced Citations (24)
Foreign Referenced Citations (4)
Number |
Date |
Country |
S64-29756 |
Feb 1989 |
JP |
10-55742 |
Feb 1998 |
JP |
10-241523 |
Sep 1998 |
JP |
10-324207 |
Dec 1998 |
JP |