Electrical unit

Details Electrical unit Electrical unit

2000-04-18

2001-04-10

Hoang, Tu Ba (Department: 3742)

Electric heating

Heating devices

Combined with diverse-type art device

C174S050510

Reexamination Certificate

active

06215101

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to an electrical unit containing heat-generating components inside.
(2) Description of the Related Art
Usually, an internal circuit, such as an electrical unit
100
as shown in
FIG. 9
, is installed in an electric connection box.
The electrical unit
100
includes a circuit board
10
, heat-generating components
20
soldered to a wiring pattern (not shown) on the circuit board
10
, and four terminal-attached covers
130
attached to the circuit board
10
.
On the circuit board
10
, there are formed slits
11
and V-shape cuts
12
.
Each heat-generating component,
20
is a component such as a relay
21
, a positive temperature coefficient (hereinafter, PTC) element
22
and a transistor
23
. The PTC element increases its own electrical resistance to prevent a current from flowing into the circuit when an overcurrent takes place in the circuit.
The terminal-attached cover
130
contains a base
131
made of synthetic resin, legs
132
for screwing the terminal-attached cover
130
on the base
131
, which are integrally molded with the base
131
, and the terminals
133
that penetrate the base
131
and stick out up and down. The heat-generating components
20
electrically connected to the circuit board
10
are covered with the terminal-attached cover
130
that is screwed on the circuit board
10
by screws
60
inserted into the legs
132
.
After the heat-generating components
20
are placed on the circuit board
10
, four terminal-attached covers
130
are mounted on the circuit board
10
. The heat-generating components
20
are soldered on the circuit board
10
by using an automatic soldering machine, then the circuit board
10
is divided into four parts by cutting along the slits
11
and V-shape cuts
12
. Thus, four identical electrical units are produced at a time.
A design is disclosed in Japanese Utility Model Application Laid-Open No. S61-93719, in which a circuit board
141
is covered with a cover member
140
(corresponding to the above terminal-attached cover
130
) made of flameproof resin as shown in
FIG. 10. A
part
143
installs an electrical unit
100
′ therein.
An invention is disclosed in Japanese Patent Application Laid-Open No. H3-235610, in which the cover member
140
is made of a material having high thermal conductivity prepared by mixing an inorganic material into a resin. A large amount of (50 wt % or more) glass fibers is mixed into polybutylene terphthalate (hereinafter, PBT) in order to increase the thermal conductivity.
If a heat-generating component
20
catches fire caused by a heat generation, there is a danger that the terminal-attached covers
130
might burn if the resin that is used to make the terminal-attached covers
130
is not flameproof, causing deterioration in quality of the electrical unit
100
. When the heat-generating component
142
catches fire and falls down to be in contact with another heat-generating component
142
′, there is a danger that the heat-generating component
142
′ also might catch fire if no measure to prevent the heat-generating component
142
shown in
FIG. 10
from falling down is taken, causing deterioration in quality of the electrical unit
100
.
When the cover member
140
is made of a material having high thermal conductivity prepared by mixing a large amount of an inorganic material into a resin, there is no problem with respect to the material itself of the cover member
140
, however a cost of molding the cover member
140
increases since a molding condition thereof becomes severe.
SUMMARY OF THE INVENTION
It is therefore an objective of the present invention to solve the above problem and to provide an electrical unit, in which damage caused by heat-generating components catching fire therein is minimized without raising the molding cost of a terminal-attached cover of the electrical unit, thereby improving a quality of the electrical unit.
In order to attain the above objective, the present invention provides an electrical unit containing a terminal-attached cover that covers a plurality of heat-generating components mounted on a circuit board, the terminal-attached cover comprising: a base; surrounding walls extended vertically downwardly from peripheries of the base; and terminals that penetrate the base and stick out up and down, wherein the terminal-attached cover made of flameproof resin is integrally molded. Therefore, even if the heat-generating component catches fire, the terminal-attached cover will hardly burn, thereby preventing the fire from spreading.
One or a plurality of partitioning walls for setting the heat-generating components apart from each other are attached to the back of the base so as to prevent the heat-generating components from coming into contact with each other caused by falling down of the heated heat-generating component. Therefore, even if the heat-generating component catches fire and starts to fall, the partitioning wall prevents the heat-generating component from coming into contact with a neighboring heat-generating component.
At least one supporting rib is attached to the back of the base around the heat-generating components. Therefore, upon starting to fall, the burning heat-generating component abuts on the supporting rib, resulting in its not falling down.
Preferably, a plurality of pairs of the supporting ribs are arranged in such a manner that a pair of the supporting ribs facing with each other puts the heat-generating component therebetween. Therefore, the supporting ribs prevent the heat-generating component from falling.
Thus, in the electrical unit according to the present invention, damage caused by the burning of heat-generating components therein is minimized without raising the molding cost of a terminal-attached cover of the electrical unit, thereby improving a quality of the electrical unit.


REFERENCES:
patent: 5057650 (1991-10-01), Urushibata et al.
patent: 5793277 (1998-08-01), Ichikawa et al.
patent: 5892413 (1999-04-01), Okimura
patent: 6068523 (2000-05-01), Takahashi
patent: 61-93719 (1986-06-01), None
patent: 3-235610 (1991-10-01), None

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