JPH0822758A - Overload protective device - Google Patents

Abstract

PURPOSE:To widen a use adapting range, and facilitate protection by fixing a pair of movable electric contact points fixed to the bending inside both ends of a thermostat element and thermosensible movable contact points opposed to these to a thermosensible case, and forming an outer shell. CONSTITUTION:A thermostat element 2 is housed in a thermosensible case 1, and is bent in a circular pan shape. A pair of movable electric contacts 3 and 4 fixed to the bending inside both ends are provided, and the contacts 3 and 4 are opposed to each other on an inside surface of the case 1. In fixed electric contacts 5 and 6, one ends are fixed to the inside surface of the case 1 so as to be opposed to the contacts 3 and 4, and the other ends extend in the direction for separating from the case 1. Here, a screw 7 penetratingly passes through a central part of the element 2, and is fixed to the case 1, and at ordinary time, the contact points 3 and 4 contact with the contacts 5 and 6, and when a preset temperature is attained, the element 2 reverses, and adjusts so that the contacts M 3 and 4 and the contacts 5 and 6 separate from each other. Then, when a resistance value of a heater 10 is selected according to an electric current of a motor, a thermal balance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overload protection device attached to the outer shell of a hermetic compressor motor used in electric refrigerators and air conditioners.

[0002]

2. Description of the Related Art Generally, a hermetic compressor motor is
If for some reason the operation cannot be performed normally,
An overload protection device using a thermostat element such as a bimetal is attached for the purpose of protecting electric equipment using it from supposed overheat and overcurrent.

Conventionally, there are the overload protection devices as shown in FIGS. 6, 7 and 8. In the overload protection device of FIG. 6, the fixed contact terminals 113, 11 are provided in the case 102.
4 is fixed. Reference numeral 107 is a bimetal, and movable contacts 108 are fixed to both ends, and contact pressure is applied to the fixed contact terminals 113 and 114 by screws 105. The bimetal 107 is adjusted by the screw 105 so as to invert at the selected temperature. A small-diameter projection 105a is provided at the tip of the screw 105.
a is fitted into the through hole 107a at the center of the bimetal 107, the fixing plate 109 into which the protrusion 105a is fitted is located on the bimetal 107, and the protrusion 105a, the bimetal 107 and the fixing plate 109 are soldered and fixed by the solder 110. ing.

A coil spring 112 is mounted between the bimetal 107 and the case 102, and the coil spring 11
The bimetal 107 is biased upward in FIG. A heater terminal 115 is fixed to the case 102, and a heater 117 is fixed between the heater terminal 115 and the fixed contact terminal 114. As the energizing circuit, the fixed contact terminal 113, the movable contact 108, the bimetal 107, the movable contact 108, the fixed contact terminal 114, the heater 117, and the heater terminal 115 are formed in this order. 11
A cover 6 covers the opening of the case 102.

In the overload protection device shown in FIG. 7 and FIG. 8 which is a sectional view thereof, 126 is a box made of metal, and one end of a bimetal 127 curved so as to snap inside is fixed by soldering with a solder 110. Has been done. A movable contact 128 is fixed to the other end of the bimetal 127. Reference numeral 122 denotes a lid, which is made of metal and seals the box body 126 via an insulating paper 124. A fixed contact 123 is fixed to the lid 122 on the side of the box body 126 at a position where it abuts the movable contact 128. A heater 125 wrapped in an insulator 130 is wound around the outer periphery of the box 126, and one end of the heater 125 is connected to the box 126. As the energizing circuit, the heater 125, the box 126, the bimetal 127, the movable contact 128, the fixed contact 123, and the lid 122 are arranged in this order.

Further, these overload protection devices are generally shown in FIG.
It is used by being electrically connected to the motor as indicated by 0.

The operation principle of these conventional overload protection devices will be described below. Connect to the motor when an abnormality occurs in the motor such as when the winding of the motor is short-circuited or the input / output terminals are short-circuited inside the airtight container or the rotor of the motor is mechanically restricted and cannot rotate. If the motor cannot operate normally due to an abnormality in the electrical components such as the starting relay and condenser, the current including the circuit including the overload protection device is usually several to several tens of times that of normal use. Is energized.

In response to this current, the overload protection device heats the heater 117 or the heater 125 owned by the overload protection device to give a heat load to the bimetal 107 or the bimetal 127, and at the same time, the bimetal 107 or the bimetal 127 itself generates heat. The bimetal 107 or the bimetal 127 is inverted, and the two movable contacts 108 and the fixed contact terminals 113 and 114 or the movable contact 128 and the fixed contact 123 are separated from each other to interrupt the circuit.

The time from energization to circuit interruption is determined by the thermal balance between the two and is generally bimetal 10.
7 or the resistance of the bimetal 127 has a great influence on the breaking time, but when selecting the overload protection device so that the circuit is broken in about the same time for the motors that have different current values depending on the model, its length and The heater 117 or the heater 125 is selected and used in order to cope with it by a relatively simple construction method such as changing the resistance value depending on the thickness. As an example of these, the heater 117 used in the overload protection device shown in FIG. 6 is shown in FIG. In FIG. 9, (a) is processed into a flat shape, and is bent in a complicated manner in the heater housing space in order to secure the required length. In a portion having a small bending radius, the heater 117 is easily crushed by the mold during processing, which also causes a break in the heater 117. (B)
Is processed into a coil shape, and its length can be secured more freely than in (a), but the wire diameter is limited, and the position of the heater 117 is difficult to determine, and variations in characteristics are likely to occur.

On the other hand, the overload protection device should not have its protection function against the inrush current generated at the time of starting the motor and the motor operating current at the time of normal use, and the operating environment between normal time and abnormal time The protection function must be activated appropriately in response to temperature fluctuations and changes in the connected load conditions to ensure stable motor operation. When selecting an overload protection device that is suitable for a motor, it is necessary to make a careful selection of the protection function against these state changes, and tests have been carried out assuming various state changes.

[0011]

However, in the configuration shown in FIG. 6, the two movable contacts 108, the fixed contact terminals 113 and 114, the screw 105, and these and the heater 117 are used.
The storage space of the heater 117 is limited due to the insulation distance between the heater 117 and the heater 117, and the length and thickness of the heater 117 must be limited. Further, in the structure as shown in FIG. 7 and FIG.
The degree of freedom of selection is inevitably smaller than that shown in FIG. 6, and since the heater 125 is exposed to the outside of the overload protection device, there is a thermal balance between the heat generation of the heater 125 and the heat generation of the bimetal 127. It was difficult to take, and it was not possible to supply an overload protection device with a wide range of usage adaptability, so more detailed examination was required when selecting a protection device. This further increases the variety of overload protection devices,
It also has disadvantages in terms of productivity and cost.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an overload protection device which has a wide range of usage adaptability and can be easily adapted to a motor.

[0013]

In order to achieve this object, an overload protection device of the present invention comprises a thermosensitive case forming a part of an outer shell, and a thermostat which is housed in the thermosensitive case and curved in a circular dish shape. Element, a pair of movable electric contacts fixed to both ends of the inside of the curved shape of the thermostat element, a pair of fixed electric contacts fixed to the thermosensitive case so as to face the movable electric contact, and the thermosensitive case A heater case forming an outer shell and a heater housed in the heater case are provided.

Further, the present invention further comprises a heater support fixed to the heater case and provided with a plurality of step portions electrically connected to the heater.

[0015]

In the overload protection device of the present invention, the outer shell is divided into the heat sensitive case and the heater case, and the heater is housed in the heater case. The overload protection device can be selected freely, the thermal balance between the heater and the thermostat element can be easily achieved, the applicable range of use is wide, and the overload protection device easily adapted to the motor can be selected.

Moreover, since the distance between the heater and the thermostat element can be selected by the heater support having a plurality of steps, the thermal balance between the heater and the thermostat element can be easily obtained, and the motor can be easily used in a wide range of usage adaptability. The overload protection device that conforms to can be selected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an overload protection device according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the overload protection device of the same embodiment. FIG. 3 is a plan view of the heater of the same embodiment.

In FIGS. 1, 2, and 3, reference numeral 1 is a heat-sensitive case forming a part of the outer shell. Reference numeral 2 denotes a thermostat element housed in the heat sensitive case 1 and curved in a circular dish shape. The thermostat element 2 has a pair of movable electric contacts 3 and 4 fixed to both ends on the inner side of the curve. Facing the inner surface of. Fixed electrical contacts 5 and 6 are fixed to the inner surface of the heat sensitive case 1 so that one end faces the movable electrical contacts 3 and 4, and the other end extends in a direction away from the heat sensitive case 1.

Reference numeral 7 denotes a screw which penetrates the central portion of the thermostat element 2 and is fixed to the thermosensitive case 1. The movable electric contacts 3 and 4 normally contact the fixed electric contacts 5 and 6, and the thermostat is set under the set temperature condition. The position of the thermostat element 2 is adjusted so that the element 2 is inverted and the movable electric contacts 3 and 4 are separated from the fixed electric contacts 5 and 6. Reference numeral 8 denotes a spring which is located between the thermostat element 2 and the thermosensitive case 1 and which is penetrated by the screw 7. The spring 8 supports the thermostat element 2 when the thermostat element 2 is inverted.

Reference numeral 9 is joined to the heat-sensitive case 1,
Together with this, it is a heater case that forms an outer shell. Reference numeral 10 denotes a heater housed in the heater case 9 so as to face the curved outer surface of the thermostat element 2. Reference numerals 11 and 12 denote heater supports fixed to the heater case 9 and having one end electrically connected to the heater 10.
The other end of 1 is electrically connected to the other end of the fixed electrical contact 5,
The other end of the heater support 12 serves as an external connection terminal of the overload protection device. 13 is fixed to the heater case 9,
In addition, the pin receptacle is electrically connected to the other end of the fixed electrical contact 6.

As the energizing circuit, the pin receptacle 1 is used.
3, a fixed electric contact 6, a movable electric contact 4, a thermostat element 2, a movable electric contact 3, a fixed electric contact 5, a heater support 11, a heater 10, and a heater support 12 constitute a circuit in this order.

The operation of the overload protection device configured as described above will be described below. The thermostat element 2 and the heater 10 generate heat due to an overcurrent that is supplied when a motor abnormality or an electrical component abnormality occurs. In an overload protection device used for a motor which is expected to have a relatively large current, the heater 10 has a low resistance value, that is, a thick wire diameter or a short overall length, such as the heater 10a shown in FIG. 3 (a). Since the current value is large, the heat generated by the thermostat element 2 is also large, and the ratio of the thermostat element 2 to the thermal balance is large.

On the other hand, the heater 10 of the overload protection device used for the motor, which is assumed to have a relatively small current, has a high resistance value, that is, a thin wire diameter or a long overall length, for example, shown in FIG. 3 (b). The heater 10b is used. Since the current is small, the heat generation of the thermostat element 2 is also small, and the thermal balance is relatively large in the heater 10. Although the heater 10 having various shapes is selectively used as the overload protection device to cope with various motors, the overload protection device of the present invention has a configuration in which the heater 10 is housed in the heater case 9. The storage space is large and the heater 10 can be selected freely, and the thermostat element 2
Can be placed over the entire surface. This allows the heater 10 to be arranged with an optimum thermal balance, and the overload protection device selected as such has a wide temperature and current protection range and is used for a large number of adaptive motors.

Next, a second embodiment according to the present invention will be described with reference to the drawings. The same components as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 4 is a perspective view of an essential part of an overload protection device according to a second embodiment of the present invention. FIG. 5 is a sectional view of the same embodiment.

In FIGS. 4 and 5, 14 and 15 are heater supports fixed to the heater case 9 and provided with a plurality of step portions 14a and 15a connected to the heater 10.
The plurality of stepped portions 14 a and 15 a are step-like ones in which a portion substantially perpendicular to the surface of the thermostat element 2 and a portion substantially parallel to the surface of the thermostat element 2 are repeated.
The distance between a and 15a is constant regardless of the distance from the thermostat element 2.

In this embodiment, the heater supports 11 and 12 of the overload protection device according to the first embodiment are provided with a plurality of step portions 14.
In place of the heater supports 14 and 15 provided with a and 15a, the other structure is the same as that of the first embodiment.

In this embodiment, the distance between the heater 10 and the thermostat element 2 can be changed by electrically connecting the heater 10 to the step portions 14a, 15a of the heater supports 14, 15 fixed to the heater case 9. As a result, a more suitable thermal balance position can be secured and the temperature and current protection range is wide, and the motor is selected and used for a large number of adaptive motors.

[0030]

As described above, according to the present invention, the heat sensitive case forming a part of the outer shell, the thermostat element housed in the heat sensitive case and curved in a circular dish shape, and both ends of the inside of the curved inner side of the thermostat element. A pair of movable electric contacts fixed to the heat sensitive case, a pair of fixed electric contacts fixed to the heat sensitive case so as to face the movable contact, a heater case joined to the heat sensitive case to form an outer shell, and the heater. Since the overload protection device is composed of the heater housed in the case, the heater housing space can be made large, so the thickness and length of the heater can be freely selected, and the thermal balance between the heater and the thermostat element is easy. Therefore, an overload protection device that has a wide range of usage compatibility and can be easily adapted to a motor can be selected.

Further, since the heater support having a plurality of step portions fixed to the heater case and electrically connected to the heater is provided, the distance between the heater and the thermostat element can be selected, so that the heater and the thermostat element can be selected. The overload protection device that can easily balance the heat of the motor, has a wide range of usage compatibility, and can be easily adapted to the motor can be selected.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of an overload protection device according to the present invention.

FIG. 2 is an exploded perspective view of the overload protection device according to the embodiment.

FIG. 3A is a plan view of a heater used in the same embodiment when applied to a motor which is assumed to have a relatively large overcurrent. FIG. 3B is applied to a motor which is assumed to have a relatively small overcurrent. In this case, a plan view of the heater used in the same example

FIG. 4 is an exploded perspective view of essential parts of a second embodiment of an overload protection device according to the present invention.

FIG. 5 is a sectional view of the overload protection device of the same embodiment.

FIG. 6 is a sectional view showing an example of a conventional overload protection device.

FIG. 7 is a plan view showing another example of a conventional overload protection device.

FIG. 8 is a sectional view of an overload protection device of the conventional example.

9A is a plan view showing an example of a heater used in a conventional overload protection device. FIG. 9B is a plan view showing another example of a heater used in a conventional overload protection device.

10A is an electric circuit diagram showing an example of a usage state of a conventional overload protection device. FIG. 10B is an electric circuit diagram showing another example of a usage state of a conventional overload protection device.

[Explanation of symbols]

 1 Heat Sensitive Case 2 Thermostat Element 3,4 Movable Electric Contact 5,6 Fixed Electric Contact 9 Heater Case 10 Heater 14,15 Heater Support 14a, 15a Steps

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Nishida 3-22 Takaidahondori, Higashi-Osaka City, Osaka Prefecture Matsushita Refrigeration Co., Ltd. (72) Inventor Yoshihide Nakajima 3-22 Takaidahondori, East Osaka-shi, Osaka Within Matsushita Cold Machinery Co., Ltd.

Claims (2)

[Claims] 1. A thermosensitive case forming a part of an outer shell, a thermostat element housed in the thermosensitive case and curved in a circular dish shape, and a pair of movable electric contacts fixed to both ends of the thermostat element on the inside of the curve. A pair of fixed electrical contacts fixed to the heat sensitive case so as to face the movable electrical contacts, a heater case joined to the heat sensitive case to form an outer shell, and a heater housed in the heater case. Overload protection device having. 2. The overload protection device according to claim 1, further comprising a heater support fixed to the heater case and provided with a plurality of step portions connected to the heater.