JP2651002B2 - Motor overload protection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor overload protection device according to the present invention.

2. Description of the Related Art Various types of motor overload protection devices have been proposed. In particular, in recent years, overload protection devices used for compressors used in refrigerators have been required to be reduced in cost and improved in reliability. For this reason, an attempt has been made to reduce the size of the overload protection device to meet the above-mentioned demands (for example, Japanese Patent Application Laid-Open No. Sho 61-2276).
No. 31). This type of overload protection device removes the thermostat element from the electric circuit, snaps the thermostat element by the heat of the heater and the heat from the compressor body, pushes down the leaf spring with the movable contact by the snap operation, and separates the contacts. The size is small, and the cost and reliability are improved.

SUMMARY OF THE INVENTION However, in the above-described conventional configuration, the thermostat element is provided with the heater on the low expansion metal side of the two or three layers having different thermal expansion coefficients forming the thermostat element with respect to the heater. Therefore, the temperature followability of the thermostat element due to the heat generated by the heater is poor, and also in terms of structure, the heater is inverted by the snap operation of the thermostat element in the outer shell case recess, and the time until the thermostat element returns again is delayed. Since it is arranged along the outer circumferential groove of the provided projection, the shape of the heater is limited within the outer circumferential groove of the protrusion inside the recess, and at the same time, the heater may be deprived of heat by contacting the inner surface of the outer shell case Had the problem of having The present invention solves the above-mentioned conventional problems, and provides an integrated start-up / overload protection device for a compressor with good mounting workability, and in particular, a device in which the temperature followability of the overload protection device with respect to current is improved. To provide.

Means for Solving the Problems In order to achieve this object, the present invention provides a starting device unit and an overload protection device unit which are separated by a partition in the same case, and the overload protection device unit is shared by a motor. A pin terminal to be connected to the terminal, a conductive fixed plate, a heater supported only by the pin terminal and the fixed plate, and a movable contact on the other side of the heater opposite to the free end, one end of which is fixed to the fixed plate. A conductive leaf spring, an external terminal having a fixed contact arranged to face the movable contact, and a plate having a central portion arranged close to the heater and the pin terminal with the high expansion side facing the heater and the pin terminal via a supporting material. A thermostat element is supported near the center of the spring and both ends are supported by a case or a fixed plate. When the thermostat element is heated above a set temperature, it snaps and separates the movable contact from the fixed contact. The leaf spring is urged in the direction.

In the motor overload protection device of the present invention, since the starting device and the overload protection device are provided in the same case,
Good installation workability. In addition, since the heater is supported only by the pin terminals and the fixing plate, and there are no obstacles such as protrusions in the space where the heater is inserted, the heater can be formed into any shape such as a winding shape or a plate shape. There are few restrictions on the shape of. Also, since the heater is supported only by the pin terminals and the fixing plate, there is little possibility that the heater comes into contact with the inside of the outer shell case, so the heat of the heater is not easily taken away by the case, and the temperature follows the heater current. Because the high expansion side of the thermostat element is placed close to the heater and the pin terminals in close proximity to the heater and the pin terminals, a short-time trip or a final trip failure state occurs in the motor, causing a large current to flow and heating the heater. Alternatively, when overheating of the motor is transmitted to the pin terminal via the common terminal, radiant heat from the heater or the pin terminal can be directly received on the high expansion side of the thermostat element and can be sensitively sensed. The thermostat element is supported near the center of the leaf spring via the support material and both ends are supported by the case or the fixed plate. When the thermostat element is snapped by being heated to a temperature higher than the set temperature, the high expansion side of the thermostat element comes closer to the heater and the pin terminal than before the snap operation, and the return of the thermostat element can be delayed. The effect improves the reliability of protection against overcurrent and overheating of the motor, and prevents burning of the motor.

Embodiment An embodiment of the present invention will be described with reference to FIGS.

1 is a case, 2 is a cover, 3 is an overload protection unit, 4
Is an activation device, and 5 is a partition, which divides the overload protection device 3 and the activation device 4 in the case 1. The case 1 is formed by molding a thermosetting resin having an insulating property into a substantially square shape, and two holes 6a, 6b, 6c, and 6d are opened in the vicinity of the partition wall 5 and two places in the starter unit 4, respectively. And fits with the protruding portions 7a, 7b, 7c, 7d of the cover 2, respectively. The cover 2 is formed of a thermoplastic resin having an insulating property into a substantially square shape, has a projection 9 on the back surface that comes into contact with the compressor body 8, and is electrically connected to the compressor body 8. Terminal 1
Circular holes 13a, 13b, 13c through which 0, 11, 12 pass are open.

In the starter unit 4, reference numeral 14 denotes a ceramic having PTC characteristics (hereinafter, referred to as ceramic), reference numerals 15 and 16 denote terminals with electrode plates, and reference numeral 17 denotes a terminal with pins. Terminal 15 with electrode plate
Is connected to an external terminal 18 having one end formed in a generally well-known shape of a 187 type or a 250 type, and a leg 19a of an electrode plate 19 formed of a material having no spring property. Another terminal 16 with an electrode plate is an external terminal 20.
And leg portions 21a of the electrode plate 21 formed of a material having a spring property.
And a pin terminal 23 formed so as to be press-fitted into the terminal 10 connected to the main winding 22 of the compressor body 8. Reference numeral 17 denotes a pinned terminal, which is an external terminal 24 formed by connecting the two external terminals 18 (one is for the fan motor 25, and the external terminal is provided if the fan motor 25 is not provided).
It becomes 18. ), And a pin terminal 27 formed so as to be press-fittable into the terminal 11 connected to the auxiliary winding 26 of the compressor body 8.
Is connected to The ceramic 14 is formed in a disc shape, is held by the contact portion 19b of the electrode plate 19 and the contact portion 21b of another electrode plate 21, and is housed in the case 1.

In the overload protection device 3, 28 is a pin terminal, 29
Is a heater, 30 is a fixed plate, 31 is a leaf spring with contacts, 32 is a terminal with contacts, and 33 is a thermostat element.

The pin terminal 28 is provided with a fitting portion 34 formed so as to be press-fittable into the common terminal 12 of the compressor body 8, and is provided with a protruding piece 28 a at the other end and connected to one end 29 a of the heater 29. The other end 29b of the heater 29 is connected to the protruding piece 30a of the fixed plate 30, and is positioned in the heater insertion space 35 in the case 1. The heater 29 used here is of a spiral type for convenience. However, since there are no protrusions or obstacles in the heater insertion space 35 that regulate the shape of the heater 29, the heater 29 has a free winding shape and a plate shape. It is clear that various shapes are possible. The fixed plate 30
The other protruding piece 30b is connected to a leaf spring 31 with a contact provided with a movable contact 37 at one end of a leaf spring 36, and a fixed plate 30.
The protrusion 30c at the other end of the case 1 comes out of the case 1 through the square hole 38 of the case 1 and is fixed to the case 1 by caulking. In the terminal with contacts 32, a fixed contact 40 is provided on the external terminal 39, and the fixed contact 40 is disposed at a position facing the movable contact 37. The external terminal 39 has a 187 type or 2 at one end.
It has two 50-type terminals (one is a fan motor 25
If the fan motor 25 is not provided, the number is one. Also, the other end has a projection 39a, which comes out of the case 1 through the square hole 41 of the case 1 and is fixed to the case by caulking. The thermostat element 33 is formed from a bimetal or a trimetal, and the head 42 of the beak-shaped projection 42 of the case 1 is formed.
There is a mechanism for performing a snap operation at a temperature set with the a and the projecting piece 30b of the fixed plate 30 as a fulcrum. 43 is a support material,
A hole 36a near the center of the leaf spring 36, a hole 33a at the center of the thermostat element 33 and a hole 44a of the washer 44 are inserted, and the thermostat element 33 is caulked and supported at a position facing the leaf spring 36. You.

 Here, the operation will be described.

Since the ceramic 14 is cold when the compressor body 8 is started, the resistance is low and the main winding 22 and the auxiliary winding are attached to the compressor body 8.
Current flows through 26, giving sufficient starting torque. When the compressor body 8 is started, the resistance of the ceramic 14 rapidly increases due to self-heating, and the current to the auxiliary winding 26 is sufficiently reduced. Here, the overload protection device 3 normally has a movable contact
37 and the fixed contact 40 are closed, but when the motor is locked or overloaded, the current flowing through the overload protection device 3 is detected, and the heat generated from the heater 29 is directly detected, and the compressor is simultaneously operated. When the heat from the main body 8 receives both heat of the outer shell temperature of the compressor from the protrusion 9 of the cover 2 which is in contact with the compressor main body 8, when the thermostat element 33 is heated to the set temperature, The leaf spring 36 supported by the supporting member 43 and the washer 44 by the snap operation with the head 42a of the beak-shaped projection 42 of the case 1 and the projection 30b of the fixing plate 30 as fulcrums.
Is lifted in the direction of the thermostat element 33, and at the same time, the movable contact 37 connected to the leaf spring 36 is lifted to open a closed circuit with the fixed contact 40.

In this embodiment, the overload protection device 3 and the starting device 4 are provided separately from each other by a partition 5 in the same case 1, and the overload protection device 3 is connected to a common terminal 12 of the compressor body 8. Pin terminal 28, conductive fixing plate 30, pin terminal 28 and fixing plate
Heater 29 supported only by 30 and one end fixed plate
A conductive leaf spring 36 having a movable contact 37 on the opposite side of the heater at the other end which is fixed to the free end and an external terminal 39 having a fixed contact 40 arranged to face the movable contact 37,
The high expansion side is disposed close to the heater 29 and the pin terminal 28 so as to face the heater 29 and the pin terminal 28, and the central portion is supported near the center of the leaf spring 36 via the support member 43 and the washer 44, and both ends are the beak-shaped
And a thermostat element 33 supported by the protruding piece 30b of the fixed plate 30.When the thermostat element 33 is heated to a temperature higher than a set temperature, the thermostat element 33 performs a snap operation, and moves the movable contact 37 to the fixed contact 40. The plate spring 36 is urged in a direction away from the main case 1. Since the overload protection device 3 and the activation device 4 are provided in the same case 1, the mounting workability is good. Further, the heater 29 is configured to be supported only by the pin terminals 28 and the fixing plate 30 and there is no obstacle such as a protrusion regulated in the heater insertion space 35, so that the heater 29 can be freely formed in a winding shape or a plate shape. The shape of the heater 29 can be reduced, and the shape of the heater 29 is less restricted. Further, since the heater 29 is supported only by the fixing plate 30 of the pin terminal 28, the possibility that the heater 29 contacts the inside of the outer shell case 1 is small.
Since the heat of the heater 29 is not easily taken away, the temperature followability of the current of the heater 29 is improved, and the high expansion side of the thermostat element 33 is disposed close to the heater 29 and the pin terminal 28 so that the compressor When a short-time trip or a final trip failure state occurs in the main body 8 and a large current flows and the heater 29 generates heat, or when overheating of the compressor main body 8 is transmitted to the pin terminal 28 through the common terminal 12, the heater 29 or The radiant heat from the pin terminal 28 can be directly received on the high expansion side of the thermostat element 33 and can be sensed sensitively.The center of the thermostat element 33 is located near the center of the leaf spring 36 via the support member 43 and the washer 44. Since both ends are supported by the head 42a of the beak-shaped projection 42 of the case 1 and the protruding piece 30b of the fixing plate 30, the thermostat element 33 is heated to a set temperature or higher and snaps. Means that the high expansion side of the thermostat element 33 comes closer to the heater 29 and the pin terminal 28 than before the snap operation, so that the return of the thermostat element 33 can be delayed. In addition, the reliability of protection against overheating is improved, and burning of the compressor body 8 can be prevented.

The case where the heater 29 is provided in the heater insertion space 35 which is disposed in close proximity to the high expansion side of the thermostat element 33 will be described with reference to FIG. FIG. 5 is a trip characteristic diagram in the present embodiment. The characteristic shown by the solid line is
This is a case where the heater 29 is arranged close to the low expansion side of the thermostat element 33, and has the same trip current X (compared to the characteristic when the heater 29 shown by a broken line is arranged close to the low expansion side of the thermostat element 33. Amps), the trip time is shorter when Y <Z and the heater 29 is arranged closer to the high expansion side. Therefore, the thermostat element 33 is connected to the heater 29.
Heat can be more sensitively sensed, and the temperature followability to the trip current can be improved.

In addition, the start-up method of this embodiment is the same as that shown in FIG.
The CR (capacitor start capacitor run) method is used, but the same effect is obtained in other start methods.

Effect of the Invention As described above, the present invention provides a starting device unit and an overload protection device unit separated by a partition wall in the same case, and the overload protection device unit has a pin terminal connected to a common terminal of the motor. A conductive fixed plate, a heater supported only by the pin terminals and the fixed plate, and a conductive leaf spring having a movable contact on a side opposite to the heater at one end fixed to the fixed plate and serving as a free end. An external terminal having a fixed contact arranged so as to face the movable contact, and a high expansion side arranged in close proximity to the heater and the pin terminal, and a central portion is supported near the center of the leaf spring via a support member. Both ends are composed of a thermostat element supported by a case or a fixed plate. When the thermostat element is heated to a set temperature or more, it snaps and urges a leaf spring in a direction to separate the movable contact from the fixed contact. Like Since the starting device and the overload protection device are provided in the same case, the mounting workability is good. In addition, since the heater is supported only by the pin terminals and the fixing plate, and there are no obstacles such as protrusions in the space where the heater is inserted, the heater can be formed into any shape such as a winding shape or a plate shape. There are few restrictions on the shape of. Also, since the heater is supported only by the pin terminals and the fixing plate, there is little possibility that the heater comes into contact with the inside of the outer shell case, so the heat of the heater is not easily taken away by the case, and the temperature follows the heater current. And the high expansion side of the thermostat element is placed close to the heater and the pin terminal, so that a short-time trip or a final trip failure state occurs in the motor, and a large current flows and the heater generates heat. When the overheat of the motor is transmitted to the pin terminal via the common terminal, the radiant heat from the heater or the pin terminal can be directly received on the high expansion side of the thermostat element and can be sensed sensitively. Is supported in the vicinity of the center of the leaf spring via the support material, and both ends are supported by the case or the fixed plate. When the thermostat element is heated above the set temperature and snaps, the high expansion side of the thermostat element comes closer to the heater and the pin terminal than before the snap operation, and the return of the thermostat element can be delayed. According to the present invention, the reliability of protection against overcurrent and overheating of the motor is improved by the synergistic effect, and an excellent motor overload protection device capable of preventing burnout of the motor can be realized.

[Brief description of the drawings]

1 (a) is a perspective view of a motor overload protection device according to one embodiment of the present invention, FIG. 1 (b) is an exploded perspective view of FIG. 1 (a), and FIG. 2 is FIG. a) a front view with a cover removed, FIG. 3 is a central sectional view in a state of connection with a compressor in one embodiment of the present invention, FIG. 4 is an electric circuit diagram by a CSCR method showing connection with the compressor, FIG. 5 is a trip characteristic diagram of the thermostat element. DESCRIPTION OF SYMBOLS 1 ... Case, 2 ... Cover, 3 ... Overload protection device part, 4 ... Activation device part, 5 ... Partition wall, 28 ... Pin terminal,
29 ... heater, 30 ... fixed plate, 33 ... thermostat element, 33b ... thermostat element high expansion side, 36 ... leaf spring, 37 ... movable contact, 40 ... fixed contact, 43 ... support material,
44 …… washer.

Claims (1)

(57) [Claims] A motor having a starting device and an overload protection device in the same case, a terminal connected to a main winding of the motor, a terminal connected to an auxiliary winding of the motor, and the motor. An overload protection device for a motor attached to a common terminal of the motor, wherein the starting device and the overload protection device are separated by a partition, and the overload protection device is a pin terminal connected to the common terminal. A conductive fixed plate, a heater supported only by the pin terminal and the fixed plate, and a conductive contact having a movable contact on a side opposite to the heater at one end fixed to the fixed plate and serving as a free end. A leaf spring, and an external terminal having a fixed contact arranged so as to face the movable contact, and a high expansion side is arranged close to the heater and the pin terminal so as to be opposed to each other, and a central portion is provided via a support member. Near the center of the leaf spring A thermostat element held at both ends and supported by the case or the fixed plate, wherein the thermostat element performs a snap operation when heated to a set temperature or higher, in a direction to separate the movable contact from the fixed contact. An overload protection device for a motor, wherein the overload protection device is configured to bias the leaf spring.