JP2001059379A - Door opening device for refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably reduce an operational force required in opening a door against the attraction of a magnet gasket, to improve the sureness and reliability in the door opening operation, and to reduce the noise level at the same time. SOLUTION: A receiving piece 2c is provided on a door 2a for a refrigerator. An electrically-driven door opening unit 9 including an electromagnetic solenoid having a push-rod 15 to press the receiving piece 2c is provided on a ceiling part of a refrigerator body 1. The electromagnetic solenoid comprises a cylindrical coil unit 12 including a frame-like yoke assembly 13, a plunger 14 with the coil unit 12 penetrated in the axial direction, a returning spring 25, etc., and the push-rod 15 is concentrically connected to the plunger 14. When the door 2a is closed, a tip part of the push rod 15 abuts on the receiving piece 2c by the spring force of a pressing spring 27, and when the coil unit 12 is energized, the plunger 14 is moved in the axial direction, and the door 2a is pressed and opened by the push-rod 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a door opening device for a refrigerator having a door which is held in a closed state by a magnet gasket.

[0002]

In recent years, refrigerators have been remarkably increased in size, and accordingly, doors for opening and closing refrigerators and the like have also been increased in size. In such a refrigerator door, it is normal that the closed state is held by the attraction force of the magnet gasket. However, when the door is enlarged, the total extension of the magnet gasket becomes longer. As a result, the operating force required to open the door tends to increase. If the operating force required to open the refrigerator door becomes large in this way, it imposes a heavy burden on a weak person (woman, child or old man), so it is desirable to take some measures.

As one of such measures, it is conceivable to provide an electric assist type door opening device that opens a door using an actuator such as an electromagnetic solenoid. In realizing such an electric assist type door opening device, it is necessary to solve various problems. That is, when an electromagnetic solenoid is employed as a drive source of the door opening device, in order to increase the reliability and reliability of the door opening operation, it is necessary to make the movement stroke of the plunger driven by the electromagnetic solenoid sufficiently large. In fact, it is necessary to use an electromagnetic solenoid having a general structure. In addition, many common electromagnetic solenoids generate a collision sound when the plunger is sucked, and there is a problem that it is difficult to reduce noise.

The present invention has been made in view of the above circumstances, and an object of the present invention is to significantly reduce the operating force required to open a door against the attraction force of a magnet gasket, and to reduce the operating force. An object of the present invention is to provide a refrigerator door-opening device that can improve the reliability and reliability of the door-opening operation and can also achieve silent operation at the same time.

[0005]

According to the first aspect of the present invention,
In order to achieve the above object, in a refrigerator provided with a door for opening and closing a storage room of the refrigerator main body, and a magnet gasket for maintaining a closed state of the door,
A cylindrical coil unit fixed to the refrigerator main body side, a plunger arranged in a state penetrating the coil unit in the axial direction, and moved in the axial direction when the coil unit is energized; And a pressing member that is provided integrally and applies a force in an opening direction to the door as the plunger is moved in the axial direction.

According to this structure, when the coil unit is energized, the pressing member exerts an opening force on the door in accordance with the movement of the integral body of the plunger and the pressing member in the axial direction of the coil unit. As a result, the door is opened against the attraction force of the magnet gasket. In this case, since the plunger is disposed so as to penetrate the coil unit in the axial direction, the moving stroke thereof can be sufficiently increased, and the reliability and reliability of the above-described door opening operation can be improved. As a result, no collision noise is generated when the plunger is sucked, so that noise can be reduced at the same time.

In this case, as in the invention described in claim 2,
A configuration may be provided that includes a return spring that urges the plunger in a direction opposite to a moving direction according to the energization of the coil unit. According to this configuration, when the coil unit is turned off, the integrated member of the plunger and the pressing member is returned to the position before the energization by the return spring, so that the pressing member protrudes greatly (that is, the pressing member Does not interfere with the projections), which is practically useful.

When such a return spring is provided, the return spring can be constituted by a compression coil spring wound around the plunger. . According to this configuration, the return spring is prevented from being twisted or buckled by the plunger. Therefore, as the movement stroke of the plunger increases, the dimension (height) required for the return spring is increased. The function of the return spring can be surely and fully exerted at all times, even in a situation where it is unavoidable that the spring becomes large.

According to a fourth aspect of the present invention, it is preferable that the pressing member has a configuration in which a tip portion for pressing the door comes into contact with the door when the door is closed. According to this configuration, when the coil unit is energized to perform the door opening operation, there is no danger that an impact sound is generated due to the pressing member colliding against the door side, which is effective in promoting noise reduction. Becomes

[0010] In the case of adopting the structure of claim 4,
According to a fifth aspect of the present invention, there can be provided a structure including a pressing spring for urging the plunger in the direction of the door and for causing the distal end portion of the pressing member to contact the door by the urging force. . According to this configuration, the tip portion of the pressing member is securely brought into contact with the door when the door is closed, so that the generation of the above-described impact sound can be reliably prevented.

In this case, as in the invention described in claim 6,
The pressing spring may be arranged at a position for pressing an end surface of the plunger opposite to the pressing member. According to this configuration, when the plunger is returned to the position before energization by the return spring, the pressing spring functions as a cushioning material that receives the return force of the plunger. This makes it possible to suppress generation of noise (sounds hitting other members), which is beneficial in promoting noise reduction. Further, since the function of the cushioning material as described above can be shared by the pressing spring, the number of parts can be reduced as compared with the case where a dedicated cushioning material is provided.

According to a seventh aspect of the present invention, both ends of the compression coil spring wound around the plunger are connected to the end of the plunger opposite to the pressing member and the end face of the coil unit facing the end. And a function of a return spring for urging the plunger in a direction opposite to a moving direction according to the energization of the coil unit by the compression coil spring, and In this configuration, a function of a pressing spring for bringing a member into contact with the door is obtained. According to this configuration, 1
By simply providing the compression coil springs, the functions of both the return spring and the pressing spring can be obtained, so that the number of parts can be reduced.

According to the present invention, the coil unit can be driven by an output of a DC power supply circuit. According to this configuration, unlike the case where the coil unit is driven by an alternating current, it does not generate a growling sound, and can realize low noise.
A larger force can be generated as compared with the case of the AC drive, and a stable door opening operation can be performed.

In this case, as in the ninth aspect of the present invention,
The DC power supply circuit includes a rectifier circuit for rectifying an output of a commercial AC power supply, and a smoothing capacitor for smoothing the rectified output.After the coil unit is cut off, the charge of the smoothing capacitor is transferred to the coil unit. May be braked when the plunger is returned by the return spring. According to this configuration, since the load current of the coil unit is supplied through the smoothing capacitor, it is possible to prevent the generation of electromagnetic noise due to the pulsation of the load current. In addition, when the integrated body of the plunger and the pressing member is returned to the position before energization by the return spring in response to the power cut of the coil unit, the return movement is performed slowly, so that the return operation of the plunger is performed. Generation of noise (hitting sound to other members) can be reliably suppressed.

In this case, a protection resistor for suppressing an inrush current flowing into the smoothing capacitor when the DC power supply circuit is turned on and a temperature of the protection resistor are detected. And a temperature detecting means for interrupting an energizing path to the coil unit when the detected temperature is equal to or higher than the upper limit temperature.
In a state where the coil unit is energized, the temperature rise rate of the protection resistor may be set to be higher than the temperature rise rate of the coil unit. According to this configuration, an excessive current does not flow into the smoothing capacitor when the power of the coil unit is turned on, so that the smoothing capacitor can be prevented from being adversely affected such as deterioration, and the reliability of the smoothing operation is improved. Become like Further, when the coil unit is energized, that is, when the temperature of the coil unit rises, the temperature of the protection resistor rises faster than the temperature of the coil unit, and the temperature of the protection resistor detected through the temperature detecting means is equal to or higher than the upper limit temperature. Then, the current path to the coil unit is cut off. Therefore, before the temperature of the coil unit rises abnormally, the coil unit can be reliably turned off. Moreover, since it is not necessary to provide a means for detecting the temperature of the coil unit on the side of the coil unit, the size of the coil unit can be reduced.

As in the eleventh aspect of the present invention, a discharge resistor having a predetermined resistance value may be connected in parallel with the smoothing capacitor in the DC power supply circuit. According to this configuration, even if the conduction path to the coil unit is disconnected for some reason, the charge of the smoothing capacitor is discharged through the discharge resistor within a predetermined time. As a result, for example, at the time of maintenance work, it is possible to prevent a situation in which the worker is electrically shocked by the charge of the capacitor.

According to a twelfth aspect of the present invention, there can be provided a configuration having a timer circuit for controlling the energization time to the coil unit to be equal to or less than a predetermined time. According to this configuration, since the coil unit is always energized for a predetermined time, the door opening operation of opening the door against the attraction force of the magnet gasket can be reliably performed according to the energization. Thus, the operating force required to open the door can be greatly reduced. In addition, since the energization time for the electric door opening unit is limited to a predetermined time, there is no danger that the electric door unit will be energized for a long time, and the abnormal temperature rise can be prevented. Become.

According to a thirteenth aspect of the present invention, the coil unit may be supported in a state of being floated from the refrigerator body. According to this configuration, even when the coil unit vibrates due to energization of the coil unit (for example, when the load current pulsates), the vibration is not easily transmitted to the refrigerator body. Therefore, it is possible to prevent the situation where the vibration is amplified on the refrigerator body side and the noise is increased.

In this case, a leg protruding from a side of the coil unit,
An elastic bush for supporting the legs on the refrigerator body may be provided.

According to this configuration, the situation in which the vibration of the coil unit is transmitted to the refrigerator main body side can be effectively prevented by the bush, and the noise can be suppressed. , The installation height of the coil unit can be reduced as much as possible, which contributes to the overall size reduction.

According to a fifteenth aspect of the present invention, a thermal fuse is provided in close contact with the surface of the coil unit, and cuts off a current path of the coil unit in a blown state, and maintains the close contact of the thermal fuse. Therefore, a covering member made of a resin material provided so as to cover the thermal fuse is provided. According to this configuration, when the temperature of the coil unit rises abnormally, the temperature is reliably transmitted to the thermal fuse.
The current path of the coil unit can be reliably cut off by the thermal fuse. In particular, when a fuse is used to cut off the current-carrying path, the current-carrying path can be reliably cut off even when the coil unit is driven by a direct current. Disappears).

In this case, the thermal fuse can be provided above the axial center position of the plunger. According to this configuration, for example, even when the lower part of the coil unit is flooded, it is difficult for water to enter the thermal fuse portion, and the operational reliability of the thermal fuse is improved.

According to the invention described in claim 17, a stopper structure for preventing the plunger from coming off can be provided at an end of the plunger opposite to the pressing member. According to this configuration, when the coil unit is energized, it is possible to reliably prevent a situation in which the integrated body of the plunger and the pressing member jumps largely forward.

[0024] According to the present invention, the pressing member has a male screw portion on the side of the connecting portion with the plunger, and the plunger is connected to a female screw portion into which the male screw portion is screwed. Alternatively, the female screw portion may have a caulking portion which is caulked to the base end of the male screw portion in a state where the male screw portion on the pressing member side is screwed into the female screw portion. According to this configuration, the connection between the plunger and the pressing member can be reliably performed, and a situation in which the plunger and the pressing member are separated carelessly can be effectively prevented.

According to the present invention, the pressing member is projected to a position where the closing of the door is prevented when the screwing state of the male screw portion into the female screw portion is loosened by a predetermined dimension. It is good also as composition. According to this configuration, when the screwing state of the pressing member to the plunger is loosened by a predetermined dimension or more, the closing of the door is prevented, so that the connection state between the pressing member and the plunger is loosened. The notification can be made, and it is possible to cope with an abnormal situation in which the pressing member comes off from the plunger and jumps out when the coil unit is energized.

According to a twentieth aspect of the present invention, in the coil unit, the charging portion is entirely resin-molded, and the lead wire lead-out portion of the coil unit is provided above the axial position of the plunger. be able to. According to this configuration, since the coil unit is resin-molded, it is possible to prevent a situation where the insulation performance of the coil unit is deteriorated due to intrusion of water, and the lead wire lead-out portion of the coil unit is connected to the shaft of the plunger. Because it is provided above the center position, even if the lower part of the coil unit is flooded, for example, it is difficult for water to enter from the lead wire lead-out part, and this also prevents the insulation performance from lowering become able to.

According to the present invention, a receiving member is provided on the side of the door with which the tip of the pressing member abuts.
A buffer member may be provided on at least one of the receiving member and the distal end of the pressing member. According to this configuration, when the coil unit is energized to perform the door opening operation, the sound generated when the pressing member presses the door is suppressed by the buffer member, so that the noise reduction is promoted. Becomes effective.

As in the twenty-second aspect of the present invention, a pressing piece having a diameter larger than other parts can be integrally formed at the tip of the pressing member. According to this configuration, when the door is pressed and opened by the pressing member, the concentration of stress at the pressed portion is reduced, so that deformation and damage of the pressed portion can be suppressed. .

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 11 show a first embodiment of the present invention, which will be described below. 7 and 8 show a front view of the refrigerator according to the present embodiment and a schematic perspective view in a state where the refrigerator door is opened. 7 and 8, in a refrigerator body 1 configured as a heat insulating box having a well-known structure, a refrigerator room 2, a vegetable room 3, an ice making room 4 as a storage room, and an internal temperature can be switched in a plurality of stages. The switching room 5 and the freezing room 6 are provided in order from the top (however, the ice making room 4 and the switching room 5 are arranged side by side). The switching room 5 has a well-known configuration used in various modes such as a freezing room, a chilled room, a refrigerator room, a vegetable room, and the like in accordance with switching of the internal temperature.

A hinge-openable door 2a is provided on the front of the refrigerating compartment 2, and a storage container (not shown) is provided on the front of each of the vegetable compartment 3, the ice making compartment 4, the switching compartment 5 and the freezing compartment 6. )
Drawer-type doors 3a, 4a, 5a and 6a are provided. A magnet gasket 2b is attached to a peripheral portion on the back side of the door 2a for the refrigerator compartment 2,
The door 2a is configured to be held closed by the magnet gasket 2b being attracted to the refrigerator body 1 side. Although not shown, other doors 3a, 4a,
Magnet gaskets are also attached to the peripheral edges on the back side of 5a and 6a.

On the front surface of the door 2a for the refrigerator compartment 2, a display panel 7 and a handle 8 are provided in a vertically arranged state (see FIG. 7). In this case, although not specifically shown,
The display panel 7 has a display for displaying the temperature in the refrigerator compartment 2 and the freezer compartment 6 and the switching mode of the switch compartment 5, and for individually switching the set temperatures of the refrigerator compartment 2, the switch compartment 5, and the freezer compartment 6. An operation switch group and the like are provided. Further, the handle 8 is provided with a space on the back surface thereof into which a user's finger enters, and is a normally-open handle switch which is turned on when the handle 8 is pulled and pressed, respectively. (Not shown). The handle switch can be constituted by a mechanical switch such as a micro switch, but can also be constituted by an optical switch or a magnetic switch using a photo interrupter.

On the ceiling of the refrigerator main body 1, an electric door unit 9 for applying a force in the opening direction to the door 2a for the refrigerator compartment 2 has an edge opposite to the hinge portion of the door 2a. It is attached in a state located near the part, below,
The electric door unit 9 will be described with reference to FIGS. 1 is a longitudinal sectional view of the electric door unit 9 and the upper part of the refrigerator, FIG. 2 is a plan view of the electric door unit 9 with a cover removed, and FIG. 3 is a side view of an electromagnetic solenoid 11 of the electric door unit 9. FIG. 4 is a plan view showing the electromagnetic solenoid 11 in partial cross section, FIG. 5 is a perspective view showing the main part of the electromagnetic solenoid 11 in a partially exploded state, and FIG. 6 is a perspective view showing a main part of the electromagnetic solenoid 11. is there.

That is, in FIGS. 1 and 2, the electric door unit 9 is provided with a recess 1 formed in the ceiling of the refrigerator body 1.
It is installed in a semi-embedded state in a, and has a form in which an electromagnetic solenoid 11 is housed in a resin case 10. In this case, the case 10 is
a, and a cover 10b for covering the base 10a from above. The cover 10b is engaged with the base 10a by engaging claws 10c and other engaging means (not shown). It is configured to be detachably attached. Also, the base 10a
Integrally has a rectangular frame-like flange portion 10d extending outward from the opening edge thereof.
d is fixed by screwing a plurality of locations to the ceiling of the refrigerator body 1.

The electromagnetic solenoid 11 has a structure as shown in FIGS. That is, the electromagnetic solenoid 11 is formed in a cylindrical shape as a whole, and includes a coil unit 12 including a rectangular frame-shaped yoke assembly 13.
And the coil unit 1 in the coil unit 12.
Mainly includes a plunger 14 made of a magnetic material and provided in a state penetrating the yoke assembly 2 and the yoke assembly 13, and a push rod 15 (corresponding to a pressing member) made of a nonmagnetic metal coaxially fixed to the plunger 14. It is a component.

As shown in FIG. 4, in particular, the coil unit 12 is formed by winding a coil wire around a cylindrical resin bobbin 12a for, for example, about 3500 turns to form a coil 12b. The outer shell case 12c is formed by molding with an unsaturated polyester resin.

In this case, as shown in FIG. 5, the outer shell case 12c is integrally formed with a rectangular flange portion 12d protruding upward at an upper portion at one end thereof.
A flange portion 12e having the same shape as the flange portion 12d is provided above the position near the other end side.
Are integrally formed with the lead wire lead-out portion 12f protruding from the side of the lead wire. Therefore, the lead wire lead-out portion 12f is provided above the axial center position of the plunger 14. Note that lead wires 12g and 12h connected to both ends of the coil 12b are drawn out from the end surface of the lead wire drawing portion 12f.

Further, on the side surface of the outer shell case 12c on the side of the lead wire lead-out portion 12f, a pair of pedestal portions 12i, 12i are located at a predetermined distance from each other so as to be located between the flange portions 12d and 12e. And are integrally formed. Each pedestal portion 12i has a pair of terminals 16
a, 16b are attached by, for example, fitting means. Each terminal 16a, 16b has a thermal fuse 1
A pair of terminals drawn out from both ends of 7 are respectively connected by soldering. The thermal fuse 17 is provided on the surface of the outer shell case 12c (that is, the surface of the coil unit 12).
The outer shell case 1
A coating member 18 made of an insulating resin material (for example, silicone gel) is applied to the surface of 2c so as to cover the main body of the thermal fuse 17 in order to keep the thermal fuse 17 in close contact. A resin cover 19 is provided on the side surface of the outer shell case 12 between the flange portion 12d and the lead wire lead-out portion 12f so as to cover the thermal fuse 17 and the covering member 18.

A terminal 16a connected to one end of the thermal fuse 17 has a lead wire 12 for the coil 12b.
g is connected to the distal end, and the terminal 16 b connected to the other end of the thermal fuse 17 is connected to the base end of the lead wire 20. The tip of the lead wire 20 is connected to a connector 21 (see FIG. 4) together with the tip of the lead wire 12h for the coil 12b. Note that the lead wires 12g and 20g
Is configured to be routed while being inserted into a hole 19 a formed in the cover 19.

Turning to FIGS. 3 and 4, yoke assembly 13
Is a first yoke 13a bent in a U-shape corresponding to the outer shape of the coil unit 12, and an opening end of the first yoke 13a (an opening end on one side of an axial end of the coil unit 12). And a third yoke 13c in the form of a rectangular plate arranged outside the second yoke 13b. In this case, the plunger 1 is attached to each of the yokes 13a to 13c.
4 are provided with through holes (not numbered). The first yoke 13a integrally has a leg 13d bent at a right angle at the lower end thereof, and the third yoke 13c is
It has a leg 13e bent at a right angle on the lower end side. In this case, two daruma holes 13f opening in a direction perpendicular to the axial direction of the coil unit 12 are formed back to back on one leg 13d, and the other leg 13e is formed.
Is formed with one daruma hole 13f opened in a direction orthogonal to the axial direction of the coil unit 12. As shown in FIG. 3, each of the legs 13d and 13e is bent at a position above the lowermost end surface of the yoke assembly 13 by a predetermined dimension (for example, about 4 mm).

In particular, as shown in FIG. 4, cylindrical auxiliary yokes 22a and 22b are arranged on the inner periphery of the bobbin 12a of the coil unit 12 at a predetermined interval from each other. In this case, the auxiliary yokes 22a and 22b
One end face is a first yoke 13a and a second yoke 13b
Are arranged so as to abut each other. In the bobbin 12a, the inner diameter of the portion where the auxiliary yokes 22a and 22b are arranged is formed to be larger than the other portions, whereby the inner peripheral exposed portion of the bobbin 12a and the auxiliary yoke 22a are formed.
The inner peripheral surfaces of a and 22b are configured to be flush. A cylindrical sleeve 23 through which the plunger 14 is inserted is disposed in the bobbin 12a.
3 opening edges (the first yoke 13a and the third yoke 13c).
Is fixed by caulking to the through-hole (the edge of the unmarked hole). The sleeve 23 is made of a non-magnetic metal such as brass or copper.

The plunger 14 and the push rod 1
5 has a structure described below. That is, the push rod 15 has a cylindrical shape as a whole,
A disc-shaped pressing piece 15a having a diameter larger than that of other parts is formed at the distal end portion by a header process, and has a male screw portion 15b at a base end side (a coupling portion side with the plunger 14).
In addition, as shown particularly in FIG.
The portion adjacent to the male screw portion 15b is partially chamfered, and a small-diameter portion 15c having a cross-sectional shape close to a substantially rectangular shape is formed in this portion. The push rod 15
A rubber cap 24 (corresponding to a cushioning member) is attached to the front end portion so as to cover the pressing piece 15a.

The plunger 14 has a cylindrical shape as a whole, and has a female threaded portion 14a into which the male threaded portion 15b is screwed, and a female threaded portion 14a of the female threaded portion 14a. A relatively thin cylindrical portion 14b (corresponding to a caulked portion) integrally formed so as to protrude from the opening edge. When connecting the plunger 14 and the push rod 15, the external thread 15 b of the push rod 15 is connected to the female thread 14 a of the plunger 14.
Is screwed to the final position, and the cylindrical portion 14b is swaged to the small-diameter portion 15c on the push rod 15 side (FIG. 6).
reference). Thus, the push rod 15 is coaxially connected to the plunger 14 in a detented state.

At the base end side of the plunger 14, a C ring 14c (corresponding to a retaining structure) is provided.
The C-ring 14c prevents the plunger 14 from coming off in the direction of arrow A in FIGS. 3 and 4. A return spring 25 composed of a compression coil spring is wound around the plunger 14 so as to apply an extension force between the C ring 14c and the end face of the yoke assembly 13. The wire diameter of the return spring 25 is set to be larger than the difference between the inner diameter of the return spring 25 and the outer shape of the plunger 14.

The electromagnetic solenoid 1 configured as described above
1, the plunger 14 and the push rod 15 are urged in the direction of arrow A in FIGS. 3 and 4 in the energized state (the state in which the coil 12b of the coil unit 12 is energized), and the energization is stopped. The plunger 14
Then, the push rod 15 is returned to the original position by the spring force of the return spring 25.

Turning to FIGS. 1 and 2, the electromagnetic solenoid 1
The elastic bush 26 made of rubber, for example, is attached to a total of three daruma holes 13f formed in one leg 13d and 13e. In addition, each bush 2
Reference numeral 6 denotes an annular groove (without reference numeral) formed concentrically on the outer peripheral surface thereof, and this annular groove is press-fitted into the periphery of the darma hole 13f in the legs 13d and 13e from the opening side of the darma hole. It is attached by the thing.

The case 10 for accommodating the electromagnetic solenoid 11 has a total of three boss portions 10 at respective positions corresponding to the three daruma holes 13f at the bottom of the base 10a.
e (only two are shown in FIG. 1), and the electromagnetic solenoid 11 is connected to the legs 13d and 13e as described above.
The bush 26 attached to the base 10 is press-fitted into each boss 10e from above and then screwed into the boss 10e.
a. In such a mounted state, there is a gap of about 1 mm between the lower surface of the electromagnetic solenoid 11 (the lower surface of the coil unit 12 and the yoke assembly 13) and the upper surface of the base 10a, that is, the electromagnetic solenoid 11 It is assumed to be in a floating state.

In the case 10, there is provided a pressing spring 27 comprising a torsion coil spring for restricting the movement of the plunger 14 rearward (in the direction of the arrow A in FIGS. 1 and 2). . More specifically, the pressing spring 27 is supported by fitting its eyeball 27a to a boss 10f integrally formed upright on the base 10a. 14 and between the end face on the base end side and the rising wall surface of the base 10a.

Thus, the pressing spring 27 urges one end surface of the plunger 14 in the direction of arrow A against the returning spring 25. In the steady state in which the door 2a is closed, the push rod 27 is pushed. The configuration is such that the distal end portion of 15 (the pressing piece 15a with the cap 24 attached) abuts on the door 2a side by the urging force of the pressing spring 27.
The urging force of the pressing spring 27 is naturally set to a level smaller than the attraction force of the magnet gasket 2b.

On the other hand, at the upper edge of the door 2a for the refrigerator compartment 2 at a position outside the magnet gasket 2b, a receiving member 2c against which the distal end of the push rod 15 abuts vertically when the door 2a is closed. Are provided integrally, and when the electromagnetic solenoid 11 is energized, the plunger 1
When the push rod 4 and the push rod 15 are urged in the direction of arrow A, the receiver 2c is pressed by the push rod 15, and the door 2a is opened in response to the attraction force of the magnet gasket 2b. Has become.
A pressed plate 28 (corresponding to a buffer member) made of, for example, rubber is attached to the pressed portion of the receiving member 2c.

FIG. 9 shows a circuit configuration related to the electric door unit 9 of the electric configuration of the refrigerator according to the present embodiment, which will be described below. In FIG. 9, the electromagnetic solenoid 1 in the electric door unit 9 is shown.
Reference numeral 1 denotes a configuration in which the output of the DC power supply circuit 29 is driven by the DC through the thermal fuse 17. In this case, the DC power supply circuit 29 comprises a full-wave rectifier circuit 30 and a smoothing capacitor 31 receiving the rectified output thereof.
Is connected. In this case, the discharge resistor 32 is connected to a position as close as possible to the smoothing capacitor 31 (a position where the distance between the wires connecting the two is as short as possible).
The resistance value is determined by the smoothing capacitor 31 and the discharging resistor 32.
Of the parallel circuit (discharge time constant when the electromagnetic solenoid 11 is not connected) is set to a value of about 60 seconds.

In the full-wave rectifier circuit 30, one AC input terminal is connected to one terminal of a commercial AC power supply 35 via a protection resistor 33 for suppressing inrush current and a normally open control switch 34. And the other AC input terminal is connected to the current fuse 3
6 and is connected to the other terminal of the commercial AC power supply 35. The control switch 34 is configured to be turned on by a timer circuit 37 for a predetermined time. The timer circuit 37 operates when the handle switch (not shown) is turned on by a pulling operation or a pressing operation of the handle 8 with the door 2a closed (a well-known door switch is turned off). The timer operation is performed for a predetermined time (for example, a fixed time in a range of about 0.3 to 2 seconds), and the control switch 34 is turned on only during the timer operation.

Hereinafter, the operation of the present embodiment having the above configuration will be described. Now, when the door 2a for the refrigerator compartment 2 is closed, as shown in FIG. 1, the magnet gasket 2b is attracted to the front surface of the refrigerator body 1, and the closed state is maintained. In this closed state, the electromagnetic solenoid 11 in the electric door unit 9 is turned off, and the cap 24 at the tip of the push rod 15 is pressed against the contact plate 28 of the receiving member 2c on the door 2a by a pressing spring 27.
Contact by the spring force.

From the closed state of the door 2a, the door 2a
When the handle switch (not shown) is turned on by pulling or pressing the handle 8 to open the door, the control switch 34 is turned on for a predetermined time by the timer circuit 37, and the inside of the electric door unit 9 is opened. Is driven by the output of the full-wave rectifier circuit 29 for a predetermined time. Then, the plunger 14 and the push rod 15 of the electromagnetic solenoid 11 are
Since it is instantaneously moved in the direction of the door 2a (the direction of arrow A in FIGS. 1 to 4) against the spring force of the return spring 25, the receiving member 2c provided on the door 2a is pressed by the push rod 15. As a result, the magnet gasket 2b is peeled off from the refrigerator body 1, and the door 2a is opened accordingly.

When the door 2a is opened as described above,
Although the push rod 15 is in a state of protruding greatly,
Thereafter, when the electromagnetic solenoid 11 is turned off,
The plunger 14 and the push rod 15 are used for the return spring 2.
5 allows the push rod 15 to be immediately returned to the original position, and the amount of protrusion of the push rod 15 is reduced. When the door 2a is opened, the plunger 14 and the push rod 15 return to a position where the spring force of the return spring 25 and the spring force of the pressing spring 27 are balanced, but when the door 2a is closed thereafter. When the push rod 15 is pressed by the receiver 2c, the push rod 15 is returned to the original position shown in FIG.

In short, according to the above-described embodiment, the electric door opening unit 9 is energized for a predetermined time in response to the ON operation of the handle switch, and applies a force in the opening direction to the door 2a. Accordingly, the door opening operation of opening the door 2a against the attraction force of the magnet gasket 2b is performed. In this case, since the plunger 14 of the electromagnetic solenoid 11 is disposed so as to penetrate the coil unit 12 in the axial direction, its moving stroke can be made sufficiently large, and the above-described certainty of the door opening operation and Reliability can be improved,
Since no collision noise is generated when the plunger 14 is sucked, noise can be reduced at the same time.

In particular, the electromagnetic solenoid 11 according to the present embodiment
In this embodiment, auxiliary yokes 22a and 22b are provided in addition to the normal yoke assembly 13, so that the plunger 14
A large force (suction force) acts on the door, and the certainty of the door opening operation is further enhanced. Incidentally, FIG.
, The displacement of the plunger 14, the suction force generated by the electromagnetic solenoid 11, and the load (the force required to open the door 2a)
Is shown. In FIG. 10, the position of the displacement “0 mm” is the magnetic stable point of the plunger 14, and
In a steady state in which the door 2a is closed (the plunger 14 is
The displacement of the plunger 14 in the position shown in FIG.
5 mm. In the present embodiment, the auxiliary yokes 22a, 22b
As shown in FIG. 10, the effective length and the disposition position are set so that the maximum suction force can be obtained when the displacement of the plunger 14 is about 30 mm (when the plunger 14 is moved about 5 mm from the original position). ing. This allows the magnet gasket 2b to be peeled off immediately before the plunger 14 is moved by about 5 mm in accordance with the energization of the coil unit 12.

In this embodiment, since the return spring 25 is provided for returning the integrated body of the plunger 14 and the push rod 15 to the position before energization after the electromagnetic solenoid 11 is cut off, the push rod 15 is large. It does not exhibit a protruding state (that is, a state in which the push rod 15 interferes as a protrusion), which is useful in practical use.

In this case, since the return spring 25 is composed of a compression coil spring wound around the plunger 14, it is difficult for the return spring 25 to twist or buckle. 24. As a result, even in a situation where the plunger 14 requires a large moving stroke as in the present embodiment and the dimension (height) required for the return spring 25 is unavoidably increased, the plunger 14 does not need to be moved. Return spring 25
Function can always be surely and sufficiently exerted. In addition, in the present embodiment, the wire diameter of the return spring 25 is set to a size larger than the difference between the inner diameter of the return spring 25 and the outer shape of the plunger 14, so that the unit coil of the return spring 25 However, it is possible to prevent a situation in which the spring function is deteriorated due to biting under another unit coil. As a result, there is no possibility that the return function of the plunger 15 by the return spring 25 is lost.

The tip of the push rod 15 is
When the door 2a is closed, the push rod 15 collides with the door 2a when the coil unit 12 is energized to perform the door opening operation because the door 2a comes into contact with the receiving member 2c on the door 2a side. This eliminates the risk of generating impulsive noise due to the above, which is effective in promoting noise reduction. In this case, since the push rod 15 is made of a non-magnetic metal that is resistant to cracking and breaking, the reliability with respect to the life is enhanced.

Further, since the pressing spring 27 for contacting the distal end portion of the push rod 15 with the door 2a is provided as described above, the distal end portion of the push rod 15 is closed when the door 2a is closed. As a result, it is possible to reliably prevent the above-described impact sound from being generated.

In this case, since the pressing spring 27 is disposed at a position for pressing the end face of the plunger 14 on the side opposite to the push rod 15, the plunger 14 is returned to the position before energization by the return spring 25. When the plunger 14 is returned, it functions as a cushioning member that receives the return force of the plunger 14. As a result, plunger 1
4 (in the case of the configuration of the present embodiment, the sound of collision with the rising wall of the base 10a) due to the return operation can be suppressed by the pressing spring 27, which is useful for promoting noise reduction. Become. Further, since the function of the cushioning material as described above can be shared by the pressing spring 27, the number of parts can be reduced as compared with the case where a dedicated cushioning material is provided.

In this embodiment, the push rod 15
Is provided with a rubber cap 24 at the tip end thereof, and a rubber backing plate 28 is also provided on the receiver 2c on the door 2a side.
Is provided, the sound generated when the push rod 15 presses the door 2a when the above-described door opening operation is performed is suppressed by the cap 24 and the backing plate 28, and the noise is reduced. It is even more effective in promoting
It is not necessary to provide both the cap 24 and the backing plate 28, and it is sufficient to provide at least one of them. Also, the tip of the push rod 15 (actually, the cap 2
4) is configured to abut vertically on the receiver 2c (actually, the backing plate 28) when the door 2a is closed. As a result, during the door opening operation, the push rod 15
This makes it difficult for the rubbing force to act on the pressed portion, thereby reducing damage to the cap 24 and the abutment plate 28, which is useful for prolonging their life.

Further, at the tip of the push rod 15,
Since the pressing piece 15a having a larger diameter than other parts is integrally formed, when the push rod 15 presses and opens the receiving member 2c of the door 2a, concentration of stress at the pressing portion is reduced. As a result, it is possible to suppress deformation and damage of the pressed portion on the receiving tool 2c side.

Since the coil unit 12, which is the drive source of the electromagnetic solenoid 11, is driven by the output of the DC power supply circuit 29, it may generate a growling sound as in the case of the AC drive. As a result, noise can be reduced and a large force can be generated as compared with the case of AC driving, so that a stable door opening operation can be performed.

In this case, the DC power supply circuit 29 includes a full-wave rectifier circuit 30 for rectifying the output of the commercial AC power supply 34 and a smoothing capacitor 31 for smoothing the rectified output. This makes it possible to prevent the generation of electromagnetic noise caused by the pulsation of the load current of the unit 12. Further, after the coil unit 12 is cut off, the charge of the smoothing capacitor 31 is reduced as shown in FIG.
, The discharge is performed in a relatively short time (for example, about 0.1 to 0.2 seconds), and braking is applied when the plunger 14 is returned by the return spring 25. As a result, when the integrated body of the plunger 14 and the push rod 15 is returned to the position before energization by the return spring 25 in response to the power cut-off of the coil unit 12, the return movement is performed slowly. 1
The generation of noise (in the case of the configuration of the present embodiment, the impact noise against the pressing spring 27) associated with the return operation of No. 4 can be reliably suppressed.

The smoothing capacitor 31 in the DC power supply circuit 29 has a discharging resistor 32 having a predetermined resistance value in parallel with the smoothing capacitor 31.
Is connected, even if the current path to the coil unit 12 is disconnected for some reason, the charge of the smoothing capacitor 31 is maintained for a predetermined time (6 in this embodiment).
Within about 0 seconds), the battery is discharged through the discharge resistor 32. As a result, for example, during a maintenance operation, it is possible to prevent a situation in which the operator is electrically shocked by the charge of the smoothing capacitor 31.

Further, since the protection resistor 33 is provided in the preceding stage of the DC power supply circuit 29, there is no possibility that an excessive current flows into the smoothing capacitor 31 when the power is turned on. As a result, it is possible to prevent the smoothing capacitor 31 from being adversely affected by deterioration or the like, thereby improving the reliability of the smoothing operation.

Since the timer circuit 37 for controlling the energization time to the coil unit 12 to be equal to or less than the predetermined time is provided, the coil unit 12 is always energized for the predetermined time. Can be reliably performed to open the door 2a against the attraction force of the magnet gasket 2b, and the operating force required to open the door 2a can be greatly reduced. Also,
Since the energizing time for the electromagnetic solenoid 11 is limited to a predetermined time, there is no danger that the electromagnetic solenoid 11 will be energized for a long time, and the abnormal temperature rise can be prevented.

The electromagnetic solenoid 11 including the coil unit 12 is supported in a state of being floated from the refrigerator main body 1 (specifically, a state in which a predetermined gap is provided between the electromagnetic solenoid 11 and the base 10a of the case 10). , Electromagnetic solenoid 11
Even if the coil unit 12 vibrates due to energization (for example, when the load current pulsates), the vibration is less likely to be transmitted to the refrigerator body 1 side. As a result, it is possible to prevent the situation where the vibration is amplified on the refrigerator body 1 side and the noise is increased.

In this case, since the elastic bush 26 is provided to support the legs 13d and 13e protruding from the side of the electromagnetic solenoid 11 on the side of the refrigerator main body 1, the vibration of the coil unit 12 is reduced. The bush 26 can effectively prevent the situation transmitted to the main body 1 side, thereby suppressing noise, and the legs 13d and 13e supported by the bush 26 are used for the coil unit 1.
2 protrudes from the side (actually, the side of the yoke assembly 13), so that the installation height of the electromagnetic solenoid 11 including the coil unit 12 can be made as small as possible, contributing to the overall downsizing. become able to.

A temperature fuse 17 configured to cut off the current path of the coil unit 12 in the blown state is provided in a state in which the thermal fuse 17 is in close contact with the surface of the coil unit 12. Since the covering member 18 made of a resin material is provided so as to cover the thermal fuse 17, when the temperature of the coil unit 12 rises abnormally, the temperature is reliably transmitted to the thermal fuse 17. As a result, the current path of the coil unit 12 can be reliably shut off by the thermal fuse 17. In particular, when the thermal fuse 17 is used to cut off the current path, the current path of the coil unit 12 that is driven by DC can be reliably cut off (as in the case of using a bimetal switch, the arc is cut after the cutoff). There is no danger that current will continue to flow).

In this case, since the thermal fuse 17 is provided above the axial center position of the plunger 14, for example, when water enters the case 10 and the coil unit 12
Even when the lower part of the thermal fuse 17 is flooded, it is difficult for water to enter the thermal fuse 17 portion, and the operational reliability of the thermal fuse 17 is improved.

An outer shell case 12c in which the entire charged portion of the coil unit 12 is resin-molded is provided.
Since the lead wire lead-out portion 12f of the coil unit 12 is provided above the axial center position of the plunger 14, it is possible to prevent the insulation performance of the coil unit 12 from being deteriorated due to the intrusion of water. Even under the condition that the lower part of the unit is flooded, it is difficult for water to enter from the lead wire lead-out portion 12f.
From this aspect, it is possible to prevent the insulation performance from being lowered.

A wiring portion for the lead wire lead-out portion 12f, the thermal fuse 17 and the like is a coil unit 12
, That is, a structure that does not straddle a movable portion such as the plunger 14 or the push rod 15, there is no possibility that those wiring portions adversely affect the function of the electromagnetic solenoid 11.

The plunger 14 is provided with a C-ring 14c for preventing the plunger 14 from coming off, so that when the coil unit 12 is energized, the plunger 14 and the push rod 15 are likely to protrude greatly forward. It will be possible to prevent it reliably.

The plunger 14 and the push rod 1
In order to connect the male screw 5 with the male screw part 15b formed on the push rod 15 side, it is screwed into the female screw part 14a formed on the plunger 14 side, and in the screwed state, a cylindrical part integrally formed on the plunger 14 side. 14b is caulked to the small diameter portion 15c on the push rod 15 side, so that the connection between the plunger 14 and the push rod 15 can be surely performed, and the situation where they are inadvertently separated can be effectively prevented. Can be prevented.

At this time, the push rod 15 can be configured so as to protrude to the position where the closing of the door 2a is prevented when the male screw portion 15b is screwed into the female screw portion 14a by a predetermined dimension. Things. According to this configuration, when the screwed state of the push rod 15 into the plunger 14 is loosened by a predetermined dimension or more, the closing of the door 2a is prevented.
With this, it is possible to notify that the connection state between the push rod 15 and the plunger 14 is loose, and it is possible to cope with an abnormal situation in which the push rod 15 comes off the plunger 14 and jumps out when the coil unit 12 is energized.

(Second Embodiment) FIG. 12 shows a second embodiment of the present invention.
Only parts different from the embodiment will be described. FIG. 12 corresponds to FIG. 9 in the first embodiment. In the second embodiment, the thermal fuse 17 in the first embodiment is removed,
Instead, a bimetal switch 38 (corresponding to a temperature detecting means) is provided. That is, the bimetal switch 38 is provided so as to detect the temperature of the protection resistor 33, and cuts off the current path to the coil unit 12 when the detected temperature becomes equal to or higher than the upper limit temperature. In this case, the protection resistor 33 is set so that the temperature rise rate in the energized state to the coil unit 12 is higher than the temperature rise rate of the coil unit 12. The temperature detecting means is not limited to the bimetal switch 38, and other means such as a temperature fuse may be used.

Also in this configuration, since the protection resistor 33 is provided, there is no possibility that an excessive current flows into the smoothing capacitor 31 when the power of the coil unit 12 is turned on. For this reason, it is possible to prevent the smoothing capacitor 31 from being adversely affected, such as deterioration, and to improve the reliability of the smoothing operation. When the coil unit 12 is energized, that is, when the temperature of the coil unit 12 rises, the temperature of the protection resistor 33 rises faster than the temperature of the coil unit 12 and the bimetal switch 38
When the temperature of the protection resistor 33 detected through the above becomes equal to or higher than the upper limit temperature, the conduction path to the coil unit 12 is cut off. Therefore, before the temperature of the coil unit 12 abnormally rises, the coil unit 12 can be reliably turned off. Moreover, the coil unit 12
Since it is not necessary to provide a means for detecting the temperature of the coil unit 12 on the side of the coil unit 12, the size of the coil unit 12 can be reduced.

(Third Embodiment) FIG. 13 shows a third embodiment of the present invention.
Only parts different from the embodiment will be described. In the third embodiment,
It is characterized in that the pressing spring 27 composed of a torsion coil spring in the first embodiment is not required. That is, in FIG. 1 showing a longitudinal sectional structure of a main part, both ends of a compression coil spring 39 wound around the plunger 14 are connected to the plunger 1.
4 and the yoke assembly 1
3 is fixed to the end face facing the C-ring 14c in a state where the plunger 14 is extended by a predetermined dimension.
Function of a return spring for urging in the direction opposite to the moving direction (direction of arrow A) in accordance with the energization of the push rod 1
5 is configured to obtain the function of a pressing spring for contacting the receiving member 2c on the door 2a side.

According to this configuration, only one compression coil spring 39 is provided, and the return spring 2 in the first embodiment is used.
5 and the function of the pressing spring 27 are both obtained, so that the number of parts can be reduced.

(Other Embodiments) The present invention is not limited to the above-described embodiment, but can be modified or expanded as follows. The pressing spring 27 is realized by a torsion coil spring, but may be realized by another spring such as a compression coil spring. Thermal fuse 17
Instead, another temperature-responsive current interrupting means (such as a combination of a temperature sensing element and a switching element or a bimetal switch) may be provided. Although the C-ring 14c is used as the retaining structure, a pin or other means penetrating through the plunger 14 in the radial direction may be used as the retaining structure. Although the electric door unit 9 for opening the door 2a for the refrigerator compartment 2 has been described, the other doors 3a, 4a, 5a, and 6a may be provided with electric door units having the same configuration.

[0083]

As is apparent from the above description, according to the present invention, when the refrigerator door is opened against the attraction force of the magnet gasket, the operation force required for opening the door can be greatly reduced. At the same time, it is possible to improve the certainty and reliability of such an opening operation, and to achieve a beneficial effect such that noise can be reduced at the same time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is a plan view of the main part.

FIG. 3 is a side view of an electromagnetic solenoid.

FIG. 4 is a plan view of an electromagnetic solenoid partially sectioned.

FIG. 5 is a perspective view showing a state where a main body of the electromagnetic solenoid is partially exploded.

FIG. 6 is a perspective view of a main part of an electromagnetic solenoid.

FIG. 7 is a front view of the refrigerator.

FIG. 8 is a perspective view of the refrigerator with the refrigerator compartment door opened.

FIG. 9 is a circuit diagram showing an electrical configuration of a main part.

FIG. 10 is a diagram showing output characteristics and load characteristics of an electromagnetic solenoid.

FIG. 11 is a diagram showing a change characteristic of an applied voltage to a coil unit.

FIG. 12 is a view corresponding to FIG. 9 showing a second embodiment of the present invention.

FIG. 13 is a longitudinal sectional view of a main part showing a third embodiment of the present invention.

[Explanation of symbols]

1 is a refrigerator main body, 2 is a refrigerator room, 2a is a door, 2b is a magnet gasket, 2c is a holder, 3 is a vegetable room, 3a is a door, 4 is an ice making room, 4a is a door, 5 is a switching room, and 5a is a door. , 6
Is a freezer compartment, 6a is a door, 8 is a handle, 9 is an electric door unit, 10 is a case, 10a is a base, 10b is a cover, 11 is an electromagnetic solenoid, 12 is a coil unit,
3 is a yoke assembly, 13d and 13e are leg portions, 14 is a plunger, 14a is a male screw portion, 14b is a cylindrical portion (caulked portion), 14c is a C ring (retaining structure), 15 is a push rod (pressing member), 15a is a pressing piece, 15b is a male screw part, 17 is a thermal fuse, 18 is a covering member, 19
Is a cover, 22a and 22b are auxiliary yokes, 23 is a sleeve, 24 is a cap (buffer), 25 is a return spring,
26 is a bush, 27 is a pressing spring, 28 is a contact plate (buffer member), 29 is a DC power supply circuit, 30 is a full-wave rectifier circuit,
31 is a smoothing capacitor, 32 is a discharge resistor, 33 is a protection resistor, 34 is a control switch, 35 is a commercial AC power supply,
Reference numeral 7 denotes a timer circuit, 38 denotes a bimetal switch (temperature detecting means), and 39 denotes a compression coil spring.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Nagao 1-6 Ota Toshiba-cho, Ibaraki-shi, Osaka F-term in TOSHIBA ABU EE Corporation (reference) 3L102 JA01 KA01 KB05 KB23 KC06

Claims (22)

[Claims] 1. A refrigerator comprising: a door for opening and closing a storage room of a refrigerator main body; and a magnet gasket for maintaining a closed state of the door, wherein a cylindrical coil fixed to the refrigerator main body side. A unit, a plunger disposed in a state penetrating the coil unit in the axial direction, and a plunger moved in the axial direction when the coil unit is energized; and a plunger integrally provided with the plunger, and the plunger moving in the axial direction. And a pressing member for applying a force in an opening direction to the door as the door is moved. 2. The refrigerator door opening device according to claim 1, further comprising a return spring for urging the plunger in a direction opposite to a moving direction according to the energization of the coil unit. 3. The refrigerator door opening device according to claim 2, wherein the return spring is constituted by a compression coil spring wound around the plunger. Door device. 4. The pressure member according to claim 1, wherein a tip portion for pressing the door abuts on the door side when the door is closed. A door opening device for a refrigerator as described in Crab. 5. The door opening device for a refrigerator according to claim 4, further comprising a pressing spring for urging the plunger toward the door, and for causing the distal end portion of the pressing member to contact the door by the urging force. An opening device for a refrigerator. 6. The refrigerator door opening device according to claim 5, wherein the pressing spring is disposed at a position for pressing an end surface of the plunger opposite to the pressing member. Door opening device. 7. The door opening device for a refrigerator according to claim 4, wherein both ends of the compression coil spring wound around the plunger are connected to an end of the plunger opposite to the pressing member and the coil unit. A return spring that is fixed to the end face facing the end in a state where the plunger is extended by a predetermined dimension and is urged by the compression coil spring in a direction opposite to a moving direction in accordance with energization of the coil unit. And a function of a pressing spring for bringing the pressing member into contact with the door. 8. The refrigerator door opening device according to claim 1, wherein the coil unit is driven by an output of a DC power supply circuit. 9. The refrigerator door opening device according to claim 8, wherein the DC power supply circuit includes: a rectifier circuit that rectifies an output of a commercial AC power supply; and a smoothing capacitor that smoothes the rectified output. And discharging the charge of the smoothing capacitor through the coil unit after the power failure to apply braking when the plunger is returned by the return spring. 10. The refrigerator door opening device according to claim 9, wherein a protection resistor for suppressing an inrush current flowing into the smoothing capacitor when the DC power supply circuit is turned on, and a temperature of the protection resistor is detected. Temperature detection means for interrupting an energizing path to the coil unit when the detected temperature is equal to or higher than the upper limit temperature, and in a state where the coil unit is energized, the temperature increase rate of the protection resistor is set to A refrigerator door opening device, which is set so as to have a value higher than the temperature rise rate. 11. The refrigerator door opening device according to claim 8, wherein a discharging resistor having a predetermined resistance value is connected in parallel with the smoothing capacitor in the DC power supply circuit. Door opening device. 12. The refrigerator door opening device according to claim 1, further comprising a timer circuit for controlling an energization time to the coil unit to a predetermined time or less. 13. The refrigerator door opening device according to claim 1, wherein the coil unit is supported in a state of being floated from the refrigerator main body. 14. The refrigerator door opening device according to claim 13, further comprising: a leg protruding from a side of the coil unit; and a resilient bush for supporting the leg on the refrigerator main body. An opening device for a refrigerator. 15. A thermal fuse which is provided in close contact with the surface of the coil unit and cuts off a current path of the coil unit when the thermal fuse is blown, and a thermal fuse for maintaining the thermal fuse in close contact therewith. The refrigerator door opening device according to any one of claims 1 to 14, further comprising a covering member made of a resin material provided so as to cover the refrigerator. 16. The refrigerator door opening device according to claim 15, wherein the thermal fuse is provided above an axial center position of the plunger. 17. The plunger according to claim 1, wherein an end of the plunger opposite to the pressing member is provided with a retaining structure for preventing the plunger from coming off. Door opening device for refrigerator. 18. The pressing member has a male screw portion on a connection portion side with the plunger; the plunger has a female screw portion into which the male screw portion is screwed; and the male screw portion on the pressing member side in the female screw portion. 18. The refrigerator door opening device according to any one of claims 1 to 17, further comprising a caulking portion which is caulked to a base end portion of the male screw portion in a state where is screwed. 19. The refrigerator door opening device according to claim 18, wherein the pressing member protrudes to a position where the screwing of the male screw into the female screw is loosened by a predetermined dimension to a position where the door is prevented from closing. An opening device for a refrigerator characterized by exhibiting an opened state. 20. The coil unit according to claim 1, wherein the entire charging portion of the coil unit is resin-molded, and a lead wire lead-out portion of the coil unit is provided above an axial center of the plunger. The refrigerator door opening device according to any one of the above. 21. A receiving member to which the distal end of the pressing member abuts is provided on the door side, and a buffer member is provided on at least one of the receiving member and the distal end of the pressing member. Claim 1 or 2
0. The refrigerator door opening apparatus according to any one of 0. 22. The refrigerator door according to claim 1, wherein a pressing piece having a diameter larger than other parts is integrally formed at a tip end of the pressing member. apparatus.