Electrically conductive contact pin having a temperature fuse function

An electrically conductive contact pin having a temperature fuse function includes an electricity conducting element formed in an approximately cylindrical shape divided into an electrode contact portion and an outer electric contact portion, a holding body for holding the electricity conducting element provided around the outer electric contact portion such that the holding body may slide along the surface of the outer contact portion, a pressing member for pressing the outer electric contact portion upward provided between the holding body and the electrode contact portion, and an actuator for actuating to expand the distance between the electrode contact portion and the outer electric contact portion upon melting of the heat sensitive electrically conductive melt body. The electrically conductive contact pin may be consisted of two electricity conducting route by having a measurement element inside. The measurement element is electrically insulated from the electricity conducting element and may be electrically disconnected together with the electricity conducting element by the operation of the actuator.

FIELD OF THE INVENTION 
This invention relates to an electrically conductive contact pin having a 
temperature fuse function, and more particularly, to an electrically 
conductive contact pin having a temperature fuse function for electrically 
connecting a battery and a charging device by functioning as an electrode 
of a charge-discharge device of a storage battery and sensing the rise of 
temperature of the battery to suspend the electricity charge or discharge. 
BACKGROUND OF THE INVENTION 
Owing to the recent popularization of portable electric devices, the demand 
for mold type storage batteries such as nickel cadmium batteries, nickel 
hydrogen batteries and lithium ion batteries is increasing. 
These batteries are manufactured usually by assembling electrodes made by 
activated material under an electrically discharged condition. Before 
delivering to customers, the batteries are charged electricity, activated 
by repeating the charge and discharge of electricity, or voltage or 
capacity of the battery is inspected by conducting the charge and 
discharge of electricity. 
When a high voltage or a large amount of electricity is charged into a mold 
type battery or electricity is charged or discharged beyond the capacity 
of the mold type battery, gases are generated inside the battery, causing 
the increase of the inner pressure as well as the increase in the inner 
temperature of the battery. In order to prevent the increase of the inside 
pressure and temperature at the occurrence of any abnormalities, a safety 
valve may be provided inside the battery to discharge the generated gases 
outside to reduce the inside pressure of the battery. However, rapid 
generation of gases inside the battery may cause splitting of the battery 
container and spreading of the organic solution used as an electrolyte 
outside together with the oxygen and hydrogen contained therein. That 
eventually might cause fire and damage the surrounding batteries and 
devices. 
As a means for charging or discharging the battery, an electrically 
conductive contact pin freely detachably provided with the charge and 
discharge device has been used. In order to ensure the contact of the 
electrically conductive contact pin with the battery electrode, a pressing 
means such as a spring or a board spring is provided so as to apply a 
pressing force to the contacting end. The conventional electrically 
conductive contact pins are also provided with a controlling means which 
can suspend the electric charge or discharge in the case of any occurrence 
of abnormalities of the battery at the time of charge or discharge. 
For instance, Japanese Patent Laid Open No. 9-204939 discloses a 
temperature sensor for measuring the battery temperature which is provided 
inside the electrically conductive contact pin wherein an electricity 
suspension means is actuated in response to a signal generated from this 
sensor. 
However, the above method of controlling the electricity charge according 
to the signal of battery voltage, electric current or battery temperature 
relies on the normal operation of the electric power supply apparatus or 
controlling apparatus. These apparatuses might work wrongly in case of 
occurrence of any failure or noise to the apparatus. That results in an 
excessive charge or discharge of the battery. Therefore, reliability of 
this method is insufficient. 
Further, in order to continuously monitor the condition of a battery by 
sensing the charge voltage, charge current and battery temperature, many 
additional means must be provided inside the electrically conductive 
contact pin as well as another means for processing the information thus 
sensed. Therefore, owing to the resultant complex structure of the 
electric conductive contact pin, the reliability of the device is 
deteriorated and the production cost of the device inevitably becomes 
high. Further, the cost of the whole apparatus for charging or discharging 
the battery also becomes high. 
SUMMARY OF THE INVENTION 
Therefore, it is an object of the present invention to solve the above 
problems by providing an electrically conductive contact pin having a 
temperature fuse function which can suspend the charge or discharge of 
electricity in response to a rise of temperature of the battery, thereby 
avoiding the occurrence of a dangerous condition caused by the temperature 
rise in the electrical device such as a battery without requiring any 
additional devices. 
In order to achieve the above object, the present invention provides an 
electrically conductive contact pin having a temperature fuse function, 
comprising: 
an electricity conducting element formed in an approximately rod shape 
comprised of an electrode contact portion and an outer electric contact 
portion, wherein the two portions are provided in the electricity charging 
direction and connected with each other by having a heat sensitive 
electrically conductive melt body therebetween; 
a holding body for holding the electricity conducting element such that the 
holding body may slide along the surface of the outer electric contact 
portion; 
a pressing means for pressing a body of the electricity conducting element 
to expand the distance between the holding body and the electrode contact 
portion, wherein the pressing means is electrically insulated from the 
electrode contact portion and the holding body and provided at a position 
around the outer electric contact portion and between the holding body and 
the electrode contact portion in a contracted condition; and 
an actuating means provided between the electrode contact portion and the 
outer electric contact portion, wherein the actuating means is 
electrically separating the electrode contact portion from the outer 
electric contact portion, conserving the repulsive energy under the 
restraint force and repulsively actuates upon release of the restraint 
force by melting the heat sensitive electrically conductive melt body such 
that the electrode contact portion and the outer electric contact portion 
are electrically separated from one another. 
Further, while above electrically conductive contact pin is comprised of a 
single electrical conducting route, the electrically conductive contact 
pin in another aspect of the present invention may be comprised of two 
electricity conducting routes by forming the electricity conducting 
element in an approximately cylindrical shape, providing a measurement 
element along the axis of the electricity conducting element, exposing 
both ends of the measurement element outside the ends of the electricity 
conducting element and insulating the measuring element from the 
electricity conducting element. 
Preferably, the measurement element at the side of the electrode contact 
portion is able to elastically move backward when receiving a reaction 
force. Above pressing means and/or actuating means are formed of an 
elastic member such as a coil spring, a heat-resistant elastic resin or a 
plate spring. 
At the initial stage, the electrode contact portion and the outer electric 
contact portion are connected by the electrically conductive heat 
sensitive melt body so that electricity may be conducted between the 
electrode contact portion and outer electric contact portion. At this 
stage, the actuating means is provided between the electrode contact 
portion and the outer electric contact portion, conserving the repulsive 
energy under a restraint force. 
The holding body is provided at a predetermined position of the charge and 
discharge device of the charge-discharge electrical apparatus. The 
electrode contact portion contacts the electrode of the battery with a 
pressing force by rendering the pressing means provided therebetween in a 
contracted condition. 
The function of the electrically conductive contact pin of the present 
invention is performed under this condition. 
If the temperature of the battery rises beyond the melting point, the heat 
sensitive electrically conductive melt body is melted so that the 
actuating means restrained by the outer electric contact portion is 
repulsively actuated in response to the release of the restraint force 
caused by the melting and consequently the electrode contact portion and 
the outer electric contact portion is separated from one another. At this 
movement, the route of electricity conduction is disconnected. Since the 
actuating means is electrically insulated from the electrode contact 
portion and the outer electric contact portion, there is no risk of 
conduction of electricity therebetween. 
The electrically conductive contact pin of the present invention may be 
comprised of two electricity conducting routes. One route is formed of the 
electrode contact portion and the outer electric contact portion, wherein 
the two portions are connected with each other by the heat sensitive 
electrically conductive melt body. The other route is formed of the 
measurement element provided inside the cylindrically shaped electricity 
conducting element in the axial direction thereof, both ends of which are 
being exposed outside the electricity conducting element to contact with 
the electrode of the battery to be charged or discharged and the terminal 
of the electricity charging apparatus. The measurement element is 
electrically insulated from the electricity conducting element. 
Owing to the repulsive actuation of the actuating means which separates the 
outer electric contact portion from the electrode contact portion and 
moves the measurement element upward, the conduction of electricity 
through the electricity conducting element as well as the measurement 
element is suspended. 
Preferably, the measuring element provided at the side of the electrode 
contact portion elastically contacts with the electrode with an 
appropriate pressing force so that the electrode of the device to be 
charged and the measuring element is more reliably electrically connected. 
The pressing means and/or actuation means may be formed of a coil spring, a 
heat resistance plastic elastic body or a plate spring. 
According to the electrically conductive contact pin having a fuse 
function, the excessive charge by high voltage or large current or 
charge-discharge of the battery beyond its capacity is prevented so that 
generation of gases inside the battery, rise of inside pressure or rise of 
battery temperature can be avoided.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
Referring now the drawings, the embodiments of the present invention are 
explained in detail as follows: 
Embodiment 1 
FIG. 1 and FIG. 2 are perspective sectional views of the electrically 
conductive contact pin of the present invention. FIG. 1 shows the 
electrically conductive contact pin of the Embodiment 1 before actuation 
of the actuating means. FIG. 2 shows another perspective view of the 
electrically conductive contact pin 1 of the Embodiment 1 after actuation 
of the actuating means. The arrow "a" in FIG. 2 is used merely for 
explanation of the drawing. 
The electrically conductive contact pin 1 of the Embodiment 1 is used for a 
single route electricity charging device and is comprised of an 
electricity conducting element 2, a holding body 3 and a coil spring 4 
used as a pressing means. 
The electricity conducting element 2 is formed of an electrically 
conductive material such as metal and is divided into an electrode contact 
portion 21 and an outer electric contact portion 22. The electrode contact 
portion 21 is formed in a rod shape having a relatively small diameter. 
The bottom end portion 22a of the outer electric contact portion 22 formed 
in a cylindrical shape is inserted into the opening 21a of the electrode 
contact portion 21 by a predetermined length with some play to form a 
mated portion. In the space created by the play of the mated portion, an 
alloy 5 having low melting point to be used as an electrically conductive 
heat sensitive melt body is filled and hardened so as to connect the 
electrode contact portion 21 and the outer electrically contact portion 22 
as an integral body. 
An inner coil spring 24 is provided between the bottom portion 21b of the 
electrode contact portion 21 and the bottom end portion 22a of the outer 
electric contact portion 22 interposed by an insulating body 23 formed of 
an electrically non-conductive material such as plastics or ceramics. The 
inner coil spring 24 is provided as an actuating means in a pressed 
condition. 
The holding body 3 formed in a cylindrical shape having an open upper end 
and an bottom end is provided around the outer electric contact portion 
22. The holding body 3 may slide along the surface of the outer electric 
contact portion 22 in the axial direction. A stopper 25 provided around 
the outer electric contact portion 22 forms a stop point of the sliding. 
The outer coil spring 4 is provided in a pressed condition around the outer 
electric contact portion 22 and between a flange 30 provided at the bottom 
end of the holding body 3 and an insulating cap 26 provided at the upper 
end 21a of the electrode contact portion 21. 
The electrically conductive contact pin 1 of the Embodiment 1 having above 
configuration functions as follows. 
Like the conventional contact pins, the electrically conductive contact pin 
1 is inserted into the holding body 3 of the charge-discharge device P 
from the bottom thereof to the extent the outer coil spring 4 contacts 
with the flange 30 of the holding body 3. Thereafter, the electricity 
conducting element 2 is moved in the axial direction so that the bottom 
end portion 21c of the electrode contact portion 21 is contacted with the 
electrode terminal C of the electrical component with an appropriate 
amount of pressing force. The upper end portion 22b of the outer electric 
contact portion 22 is connected with the socket S which is connected with 
the outside power supply apparatus (not shown). Starting from the above 
condition, the electrically conductive contact pin 1 of the present 
invention is used for its intended purpose. 
If the electric component to be charged or discharged is heated owing to 
some abnormality, the heat is transferred to the electrically conductive 
contact pin 1, raising the temperature of the pin to a predetermined 
degree. Owing to this rise of temperature, the alloy 5 having low melting 
point is melted, causing the release of the restraint force which has been 
applied on the inner coil spring 24. 
Upon releasing the restraint, the inner coil spring 24 repulsively actuate 
to press the outer electric contact portion 22 upward in the axial 
direction (arrow a in FIG. 2), and thereby separate the electrode contact 
portion 21 from the outer electric contact portion 22. By this movement, 
the electricity conducting route is disconnected. 
In this event, since the insulating body 23 and insulating cap 26 are made 
of electrically non-conductive material, the inner coil spring 24 and the 
outer coil spring 4 are electrically disconnected with each other. 
Embodiment 2 
An electrically conductive contact pin 6 having two electricity conducting 
routes is shown as Embodiment 2 while the electrically conductive contact 
pin 1 shown as Embodiment 1 has a single electricity conducting route. 
FIG. 3 is a sectional perspective view of the electrically conductive 
contact pin 6 of the Embodiment 2 before the repulsive actuation. FIG. 4 
is an expanded sectional view of the Embodiment 2 of its essential part. 
FIG. 5 is a perspective sectional view of the electrically conductive 
contact pin of the Embodiment 2 after the repulsive actuation. 
The electrically conductive contact pin 6 of Embodiment 2 is comprised of 
two electricity conducting routes by forming the electricity conducting 
element 2 of the Embodiment 1 in an approximately cylindrical shape and 
providing a measurement element 8 along the axis of the cylindrically 
shaped electricity conducting element 2 of the Embodiment 1 exposing both 
ends of the measurement element 8 outside the end of the electricity 
conducting element 7. 
The electricity conducting element 7 of the electrically conductive contact 
pin 6 of the Embodiment 2 functions as the main body which electrically 
connects the electrode terminal C and the connecting terminal (not shown) 
of the outside power supply apparatus. It is formed in a cylindrical shape 
having an open upper end and a bottom end. 
The basic configuration of this electricity conducting element 7 is 
approximately the same as that of the electricity conducting element 2 of 
the Embodiment 1, except that the diameter of the electricity conducting 
element 7 is larger than that of the electricity conducting element 2 of 
the Embodiment 1. 
An electrode contact portion 71 is formed in a cylindrical shape having an 
open upper and a bottom end. At the bottom end portion 71c of the 
electrode contact portion 71, there is provided an insert hole 71b formed 
in a flange shape. A bottom end 72b of the outer electric contact portion 
72 formed in a cylindrical shape is inserted into the upper open end 
portion 71a of the electrode electric contact portion 71 by a 
predetermined length to form a mated portion having some play. A low 
melting point material 5 is filled in the space created by the play 
between the bottom end portion 72b of the outer electric contact portion 
72 and the upper end portion 71a to be hardened so that the electrode 
contact portion 71 and the outer electrically contact portion 72 are 
connected as an integral body. 
An insulating sleeve 73 is inserted into the open bottom end 72b of the 
outer electric contact portion 72. The insulating sleeve 73 is formed in a 
cylindrical shape having a hole of a predetermined inside diameter wherein 
the measurement element 8 which is explained later is inserted. A flange 
73f is provided around the sleeve 73 so as to contact with the opening of 
the bottom end 72b of the outer electric portion 72. 
An inner coil spring 74 is provided in a pressed condition between the 
inner edge of the inserting hole 71b and the lower edge of the flange 73f 
around the insulating sleeve 73. 
Further, an insulating cap 76 having the same configuration as that of the 
insulating cap 26 of the Embodiment 1 is provided on the upper open end 
71a of the electrode contact portion 71. 
The main body of the measurement element 8 is comprised of an electrically 
conductive material such as metal and is formed in an approximately 
cylindrical shape. It performs an electrical measurement by contacting 
with the electrode terminal C. The measurement element 8 is partially 
exposed to outside at the open upper and bottom end of the electric 
conducting contact pin 6. The lower portion of the measurement element 8 
is held by an insulating sleeve 73. The upper portion of the measurement 
element 8 is held by an insulating cylinder 77 which is inserted into the 
opening of the upper end of the outer contact portion 72. 
The basic configuration and function of the measurement element 8 is the 
same as the measurement element used in the conventional electrically 
conductive contact pin. It is formed of a sliding element 81 and a storing 
cylinder 82 for storing the sliding element 81. 
The sliding element 81 constitutes the lower portion of the measuring 
element 8. The bottom end 81c of the sliding element 81 is formed in a 
cone shape and penetrates the bottom end 82a of a storing cylinder 82. The 
bottom end 81c of the sliding element 81 is exposed outside the inserting 
hole 71b of the electrode contact portion 71. Under this condition, the 
sliding element 81 is stored along the axis of the storing cylinder 82. 
A coil spring 83 is provided above the upper end 81a of the sliding element 
81 in a pressed condition so that the coil spring 83 conserve the 
repulsive energy to push the sliding element 81 downward at the contact 
point with the electrode terminal C. 
A level difference portion 81b is formed at the upper end portion 81a of 
the sliding element 81. By fitting this level difference portion 81b with 
a stopper 84 formed inside the storing cylinder 82, the sliding element 81 
is prevented from sliding off from the storing cylinder 82. 
The holding body 3 and the outer coil spring 4 have the same configuration 
as that of the Embodiment 1. 
The electrically conductive contact pin 6 of the Embodiment 2 functions as 
follows. 
Like the electrically conductive contact pin 1 of the Embodiment 1, the 
electrically conductive contact pin 6 is connected to the charge-discharge 
device P of the outside power supply apparatus to be used for its intended 
purpose. The measuring element 8 is pressed toward the electrode terminal 
C by the pressing force of the coil spring 83. 
In the event that the electrical component to be electrically charged or 
discharged is heated owing to an occurrence of a certain abnormality, the 
heat is transferred to the electrically conductive contact pin 6, thereby 
melting the low melt point alloy 5, and releasing the restraint force 
applied on the inner coil spring 74. Owing to this repulsive actuation, 
the outer electrically contact portion 72 is pressed upward in the axial 
direction (arrow b in FIG. 5) and thereby the electrode contact portion 71 
is separated from the outer electrically contact portion 72. By this 
movement, the electrical conducting route of the electricity conducting 
contact pin 6 is disconnected. 
Experimental Result 
Connecting the outer electric contact portion and the electrode contact 
portion by heating a heat sensitive melt body which is provided 
therebetween and made of a low melting point alloy melting at the 
temperature of 60.degree. C., produced an electrically conductive contact 
pin of the Embodiment 2. A battery panel was prepared by using the 
electrically conductive contact pin thus produced. 
Installed an AA type nickel cadmium battery to the battery panel thus 
prepared, and charged that battery with a constant current of 4 ampere, 
and observed the actuation of the safety valve at the time of excessive 
charging. 
When the temperature of the electrically conductive contact pin rose up to 
60.degree. C., the heat sensitive melt body provided between the outer 
electric contact portion and the electrode contact portion melted and 
electricity charging was suspended. At the time of the suspension, the 
temperature of the battery was about 80.degree. C. 
Other Possible Embodiments 
Some modifications may be made to the above Embodiments. The shape of the 
electrically conductive contact pin or electricity conducting element is 
not limited to the cylindrical shape and can be a square pillar shape. The 
actuation means and pressing means which can be used in the present 
invention is not limited to the coil spring and can be replaced with other 
elastic element such as an elastic body made of heat resistance plastics 
or a plate spring. The outer coil spring or the coil spring on the axis of 
the contact pin are provided merely to ensure the electrical connections 
and they are not prerequisite elements of the present invention. 
Because the electrically conductive contact pin of the present invention is 
provided with a means for suspending the electricity charge upon sensing 
the rise of the temperature, the contact pin can be produced in a simple 
structure and can ensure a reliable actuation. Further since the size of 
the electrically conductive contact pin of the present invention may be 
almost the same as that of the conventional contact pin, the conventional 
contact pin can be easily replaced with the electrically conductive pin of 
the present invention without changing the outer charging device. 
Consequently, the cost for providing additional sensor equipment outside 
can be saved. Further, since the electrically conductive contact pin of 
the present invention uses low melting point alloy as the heat sensitive 
melt body, the error in sensing the actuating temperature can be minimized 
and the restraint of the coil spring can be reliably ensured.