JPH083146Y2 - Overheat prevention device for electrical equipment - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention, when an electric device is used, automatically stops the energization of the electric device when the temperature rises, cools it, and re-energizes it after cooling. The present invention relates to an overheat prevention device for electric equipment.

[Prior Art] As a means for preventing overheating of an electric device, a fuse that melts and cuts off the electric current of the electric circuit when the temperature rises is sometimes used. An electronic circuit having such a function is used when it is required to automatically resume energization when the temperature of an electric device that has been opened and once increased is lowered to a normal temperature by cooling.

[Problems to be Solved by the Invention] However, if an electronic circuit in which energization is automatically restarted as described above is used, the circuit configuration becomes complicated and the space required for it also increases.

In addition, when the housing is in a closed state, as in the case of cooling the motor, for example, the time required to cool the motor whose temperature has risen is delayed, and conversely, when the housing is always open, Since there is a high possibility that failure may be caused by the intrusion of dust, it is desirable to open the housing only when the electric equipment is stopped due to a temperature rise.

As described above, it is particularly necessary to open and close the housing in an electric device in which it is desirable to close the housing in order to prevent dust during normal operation.

However, if an attempt is made to realize such a housing opening / closing operation in addition to automatic resumption of energization to the electric circuit, the circuit configuration becomes more complicated, and at the same time an electric (electromagnetic) device for opening / closing the housing is required. The required space will be expanded.

The present invention has been made in view of the above problems existing in the prior art, and has a compact structure that does not use complicated electronic circuits or electric devices, etc., and causes a failure due to the prevention of dust intrusion into the housing. An object of the present invention is to provide an overheat prevention device for an electric device, which is capable of preventing and automatically cooling the electric device whose temperature has risen and restarting it after sufficient cooling.

[Means for Solving the Problems] In order to achieve the above object, an overheat prevention device for an electric device according to the present invention is provided with a housing having a cooling opening provided with an opening / closing member, and arranged in the housing. A shape memory alloy operating member and a switch that opens and closes the electric circuit,
An elastic member for generating a bias force is provided, and when the temperature of the operation member rises to the shape recovery temperature, the shape recovery force generated by the operation member opens the circuit of the switch and the opening for cooling. The operating member, the elastic member, the switch, and the opening / closing member are connected so that the biasing force of the elastic member closes the cooling opening and closes the switch when the temperature of the operating member decreases to the softening temperature. There is.

[Operation] When the temperature of the operating member made of the shape memory alloy is lower than the softening temperature in the housing when the electric device is in a normal operating state, the operating member is in a softened state. Therefore, the elastic force of the elastic member, that is, the bias force exceeds the deformation resistance of the operation member, the closing of the switch and the closing of the cooling opening by the elastic force of the elastic member are maintained, and the operation of the electric device is continued. It

If for some reason the amount of heat generated by the electrical equipment during operation increases and the temperature inside the housing rises and the temperature of the operating member reaches the shape recovery temperature, the shape recovery force of the operating member causes the bias of the elastic member. The force exceeds the force, and the shape recovery force opens the switch to open the electric circuit and open the cooling opening.

Then, the heat generation from the heat source is stopped, and the outside air is introduced from the opened cooling opening, so that each device of the electric device is cooled in the housing, and at the same time, the operation member is also cooled.

Then, due to the temperature hysteresis of the shape memory alloy forming the operating member, the operating member softens when the temperature of the memory member becomes lower than the shape recovery temperature as well as the softening temperature. As a result, the bias force exceeds the resistance against deformation of the operating member again, so that the cooling opening is closed by the elastic force of the elastic member, the switch is closed, the electric circuit is closed, and the electric equipment is re-energized. It

[Embodiment] Next, as an appropriate embodiment according to the present invention, an overheat prevention device used for a fan motor will be described with reference to the drawings.

1 and 2 are schematic cross-sectional views of one embodiment of the present invention.

Reference numeral 1 is a housing of a fan motor (the blades of the motor and the fan are not shown).

Reference numeral 2 denotes a cooling opening portion of the housing 1, and 3 denotes a rotary door (opening / closing member) that closes the cooling opening portion 2. An upper end portion of the door 3 is a housing by a rotation supporting member 4. It is rotatably supported with respect to 1. A bell crank 5 is fixed to the upper end of the door 3.

Reference numeral 6 is an operating member made of a shape memory alloy and having a coil shape. The operation member 6 is not particularly limited in shape as long as it can repeatedly obtain a sufficient amount of deformation and recovery force. For example, it may have a leaf spring shape. As the shape memory alloy, a NiTi alloy, a CuZnAl alloy or the like can be appropriately adopted. The shape recovery temperature and the softening temperature of the operating member are selected according to the needs of the motor itself, electronic parts other than the motor, and other members. The softening temperature of the operating member 6 is preferably set sufficiently lower than the shape recovery temperature by utilizing the temperature hysteresis of the shape memory alloy forming the operating member 6. This is for sufficiently cooling the motor before reenergizing.

The lower end of the operating member 6 is connected to the bottom plate portion of the housing 1, and the upper end of the operating member 6 is connected to one end of the bell crank 5. One end of a connecting rod 7 is connected to the other end of the bell crank 5 via a pin 8.

Reference numeral 9 denotes an opening / closing lever having a hook-shaped movable contact 10 at its lower end, and the central portion of the opening / closing lever 9 is rotatably supported by the rotation support member 11 with respect to the housing 1. To the upper end of the opening / closing lever 9, the other end of the bias coil spring 12 (elastic member) whose one end is connected to the housing 1 is connected. The bias coil spring 12 is a tension spring. Further, the connecting rod 7 is provided above the opening / closing lever 9.
The other end of is connected via a pin 14.

Reference numeral 15 denotes a hook-shaped fixed contact protruding from the inside of the bottom plate of the housing 1 and provided so as to correspond to the movable contact 10. These fixed contacts 15 and movable contacts
Reference numeral 10 constitutes a switch for opening and closing the motor circuit.

It is also possible to use a micro switch or the like as the switch and operate the switch button by pressing it with the open / close lever 9 or the like.

 Reference numeral 16 is a circuit board, and 17 is a lead wire.

18 is a power element. The power element 18 is fixed by a fixing portion 19 made of a good heat conductive material, and the fixing portion 19 also functions as a heat dissipation member.

As the elastic member for generating the bias force, a tension member made of a rubber material can be used.

And the door 3, the bell crank 5, the operation member 6,
The connecting rod 7, the bias coil spring 12, the opening / closing lever 9, the movable contact 10 and the fixed contact 15 (switch) recover the shape of the operating member 6 when the temperature of the operating member 6 rises to its shape recovery temperature. Opening of switch and cooling opening 2 by force
When the door 3 is opened and the temperature of the operating member 6 drops to a softening temperature sufficiently lower than the shape recovery temperature, the biasing force of the bias coil spring 12 closes the door 3 of the cooling opening 2 and the switch. Are connected so that the closed circuit is performed.

When the temperature of the operating member 6 in the housing 1 is lower than the softening temperature in the normal operating state of the motor, the operating member 6 is in the softened state. Therefore, as shown in FIG. 1, the bias coil spring 12 pulls the upper end of the opening / closing lever 9 to the right in FIG.
And, the force pushing the opening / closing lever 9 to the left via the connecting rod 7 is exceeded, and the closing of the switch and the closing of the door 3 of the cooling opening 2 are maintained by the biasing force, and the operation of the motor is continued.

When the amount of heat generated by the motor during operation increases for some reason and the temperature inside the housing 1 rises and the temperature of the operating member 6 exceeds the shape recovery temperature, the shape recovery force of the operating member 6 causes the bell crank 5 to move. And the force of pushing the opening / closing lever 9 leftward via the connecting rod 7 exceeds the force of pulling the upper end portion of the opening / closing lever 9 rightward by the biasing force of the bias coil spring 12, and as shown in FIG. The shape recovery force opens the switch, opens the motor circuit, and opens the door 3 of the cooling opening 2.

Then, heat generation of the motor, which is a heat source, is stopped, and the outside air is introduced from the opened cooling opening 2, so that the motor in the housing 1 is cooled, and at the same time, the operating member 6 is also cooled.

Then, when the temperature of the operating member 6 becomes lower than the softening temperature as well as the shape recovery temperature, that is, when the motor is sufficiently cooled, the operating member 6 softens. As a result, the force of pulling the upper end of the opening / closing lever 9 to the right again by the bias force exceeds the force of pushing the opening / closing lever 9 to the left due to the deformation resistance of the operating member 6, so that the biasing force causes the door 3 of the cooling opening 2 to move. Is closed, the switch is closed, the motor circuit is closed, and the motor is re-energized.

3, 4, and 5 are schematic views of another embodiment of the present invention. This embodiment is also used in a fan motor, and the opening and closing type of the housing is different from the above-mentioned embodiment, and FIG. 3 is a front view and a fourth view.
FIG. 5 is a sectional view taken along line VV in FIG. 3, and FIG. 5 is a front view.

1a is a housing (motor is not shown), 2a
Is a cooling opening, and 3a is a sliding door. Door 3a is the 4th
As shown in the figure, the upper and lower ends are the grooves 20 and 21, respectively.
And is held slidably in the left-right direction in FIG.

6a is an operation member made of a shape memory alloy and having a coil shape. Both ends of the operating member 6a are connected to the left end of the door 3a and the left end of the housing 1a, respectively.

12a is a bias coil spring. The bias coil spring 12a in this case is a compression spring, and its both ends are connected to the right end of the door 3a and the right end of the housing 1a, respectively.

Reference numeral 15a is a hook-shaped fixed contact which is provided so as to project inside the bottom plate of the housing 1a. 10a is a movable contactor, and the door 3
It is provided inside the a so as to correspond to the fixed contact 15a. The fixed contactor 15a and the movable contactor 10a form a switch.

 16a is a circuit board and 17a is a lead wire.

Then, the door 3a, the operating member 6a, the bias coil spring 12a
In addition, the movable contact 10a and the fixed contact 15a (switch),
When the temperature of the operating member 6a rises to the shape recovery temperature, the opening of the switch and the door 3a of the cooling opening 2a are opened by the shape recovering force of the operating member 6a, and the temperature of the operating member 6a becomes the softening temperature. When descending, the bias coil spring 12a is connected so that the bias force of the bias coil spring 12a closes the door 3a of the cooling opening 2a and closes the switch.

When the temperature of the operating member 6a is lower than the softening temperature, the operating member 6a is in a softened state. Therefore, as shown in FIG. 3, the biasing force of the bias coil spring 12a pulling the door 3a toward the right is Due to the deformation resistance of 6a, the force of pulling the door 3a to the left is exceeded, and the door of the switch opening and cooling opening 2a is closed.
The blockage of 3a is maintained, and the operation of the motor is continued.

When the temperature inside the housing 1a rises and the temperature of the operating member 6a exceeds the shape recovery temperature, the force of the operating member 6a to pull the door 3a leftward is applied to the bias coil spring 12.
The bias force of a exceeds the force to pull the door 3a to the right,
As shown in FIG. 5, the switch is opened, the motor circuit is opened, and the door 3a of the cooling opening 2a is opened.

After that, when the temperature of the operating member 6a becomes lower than not only the shape recovery temperature but also the softening temperature, the operating member 6a is softened, so that the bias force pulls the door 3a rightward.
Due to the deformation resistance of 6a, the force pulling the door 3a to the left is exceeded, the door 3a of the cooling opening 2a is closed, the switch is closed, the motor circuit is closed, and the motor is re-energized.

Further, in order to prevent thermal destruction of a specific element in the housing, particularly a power element, one end of the operating member may be fixed to a fixing portion made of a good heat conducting material instead of being directly fixed to the housing.

Then, in any of the above-mentioned embodiments, the opening of the door of the cooling opening due to the temperature rise in the housing is used as a failure indication, or the opened cooling opening 2a is used to replace the electronic component or the circuit board. It is possible to take it out and confirm the repair.

It is obvious that the present invention can be applied not only to the fan motors shown in the above-described embodiments but also to various electric devices, and is particularly suitable for electric devices that require dust protection in normal times.

[Effect of the Invention] In the overheat prevention device for an electric device according to the present invention, when the operating member in the housing exceeds the shape recovery temperature at which the operating member in the housing recovers its shape due to an increase in heat generation amount, the operating member's shape recovering force causes The switch is opened to stop the heat generation of the electric device as the heat source, the cooling opening is opened to introduce the outside air, and each device of the electric device in the housing is quickly cooled.

Further, when the temperature of the operating member becomes lower than the softening temperature by cooling the respective devices in the housing and simultaneously cooling the operating member, the elastic force of the elastic member closes the cooling opening and the electric device. Is restarted.

Regarding re-energization after cooling the electric equipment, by utilizing the temperature hysteresis of the shape memory alloy forming the operation member, after the inside of the housing is sufficiently cooled and the temperature of the operation member becomes lower than the softening temperature. It can be done.

Therefore, with a compact configuration that does not use complicated electronic circuits or special electrical equipment, prevention of failure by preventing dust from entering the housing, quick cooling of electrical equipment that has risen in temperature, and re-cooling after sufficient cooling The starting can be done automatically.

[Brief description of drawings]

1 and 2 are schematic cross-sectional views of one embodiment of the present invention, and FIGS. 3, 4 and 5 are schematic views of another embodiment of the present invention. 3 is a front view, FIG. 4 is a sectional view taken along line VV in FIG. 3, and FIG. 5 is a front view. In the drawing, 1,1a is housing, 2,2a is cooling opening, 3,3a
Is a door, 6 and 6a are operating members, 10 and 10a are movable contacts, 12 and 12a are bias coil springs, and 15 and 15a are fixed contacts.

Claims (1)

[Scope of utility model registration request] 1. A housing having a cooling opening provided with an opening / closing member, an operating member made of a shape memory alloy arranged in the housing, a switch for opening / closing an electric circuit, and a bias force generating member. An elastic member is provided, and when the temperature of the operating member rises to the shape recovery temperature, the shape recovery force generated by the operating member opens the opening of the switch and the opening for cooling, and the temperature of the operating member. The operating member, the elastic member, the switch, and the opening / closing member are connected so that the biasing force of the elastic member closes the cooling opening and closes the switch when the temperature decreases to the softening temperature. Overheat prevention device for electrical equipment.