KR20040039908A - Motor protector - Google Patents

Abstract

PURPOSE: An apparatus for protecting a motor is provided to prevent the damage due to a movable arm and stabilize an operation of the motor by operating directly the motor without a preheating process in a state of overload. CONSTITUTION: An apparatus for protecting a motor includes a base, a plurality of connection terminals(34,35), a movable arm(32), a first and a second heat sensing element(31,33), and a heating element(39). The connection terminals(34,35) are fixed to the base and connected to a motor. The moving arm(32) is electrically connected to the connection terminals. The first and the second heat sensing elements(31,33) are used for releasing electrical connection states of the connection terminals in a state of overload. The heating element(39) is used for shortening an operating period of the first and the second heat sensing elements. The first and the second heat sensing elements are operated at different temperature.

Description

Motor protection device {MOTOR PROTECTOR}

The present invention relates to a motor protection device for protecting a motor of a compressor that can be used in an air conditioner, a refrigerator, and the like.

Typically, for motors used in compressors of air conditioners, motor protection devices are provided to detect abnormal heat or transients that may occur when the rotor of the motor is inhibited from running or the rotor is overloaded.

Such a motor protection device is illustrated in FIGS. 1 and 2. The motor protection device includes a first switch S1 connected to an electric supply circuit for supplying electric power to a motor and opening and closing the circuit, and a first and second bimetal members connected to the circuit for opening and closing the circuit. 2 switch S2.

The motor protection device includes a case composed of a first base 2 and a second bottom base 3, a first switch S1 in the first base 2, and a second switch in the second base 3. S2 is provided. The first and second switches are opened and closed according to the amount of current that is energized by itself and its ambient temperature.

The first switch S1 is fixed to the base 2 by an adjusting screw 9 and includes a cup-shaped snap acting bimetal disk 8 having movable contacts 8a and 8b at both ends, and the bimetal disk. Movable contacts 8a and 8b are detachably contacted with the fixed contacts 4a and 5a of the external connection terminals 4 and 5, and when the overload is applied, the bimetal disk 8 is snap-inverted so that the movable contacts Disconnect from the fixed contacts to cut off the current. At this time, the heater 7 for supplying heat to the bimetal disk 8 is connected to the fixed contact portion 5a so as to uniformly transfer heat to the disk.

The second switch S2 comprises two bimetal disks 11 and 13 and a movable arm 12 which react at different temperatures.

The movable arm 12 has a fixed portion 12a and a movable portion 12b at both ends, and has a projection 12c at the center thereof for inverting and snapping the bimetal disk by contact with the bimetal disk. The movable part is connected by the fixed contact 17 and the movable contact 18 of the two external connection terminals (not shown) of the second base 3 at the standard operating temperature, respectively, which external connection terminals are connected to the first base ( It is connected to the connection terminals 4 and 5 of 2), respectively.

Each of the first and second bimetal disks 11 and 13 installed in the cavity 14 of the second base 3 combines two pieces of metal having different coefficients of thermal expansion and joins the joined metals. It is produced by forming a piece into a metal piece in the form of a cup. The first bimetal disk 11 is set to be snap inverted primarily at a predetermined temperature, and when inoperable, the second bimetal disk 13 is secondly operated at a temperature higher than the temperature, thereby opening the switch. It is set to cut off the current.

However, since such a conventional motor protection device is usually installed on the outer wall of the compressor, when the temperature transmission is delayed by the outer wall of the compressor and the motor protection device senses the appropriate temperature to cut off the current, the temperature inside the motor has already reached the appropriate temperature range. The motor may be burned much higher than that, and the structure is complicated because the first and second switches are redundantly provided.

Also, taking into account the delay in temperature transfer by the compressor outer wall, the operating temperature of the second bimetallic member should be set only slightly higher than the operating temperature of the first bimetallic member, but the two bimetallics having a slight difference in operating temperature It is difficult to fabricate the member, which leads to limitations in the design of the motor protective protection device.

In addition, since the movable arm hits the movable arm during the snap reversal operation of the bimetal disc, the movable arm or the bimetal disc may be damaged, and the damage does not make contact with the bimetal disc and the movable arm, and the switch opens even when an overload is applied. There is a case where the motor protection function cannot be performed by not doing so.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor protection device which is operated immediately and stably without delay in operating time through a preheating process, when an overload is applied to a motor so as to solve the above-mentioned disadvantages of the prior art.

Another object of the present invention is to provide a motor protection device having a design degree of freedom capable of operating immediately at an operating temperature.

Another object of the present invention is to provide a motor protection device which ensures stable operation by not being damaged by an impact with the movable arm during operation.

1 is a cross-sectional view of a motor protection device according to the prior art.

2 is a circuit diagram showing the electrical connection of the motor protection device of FIG.

3 is a cross-sectional view of the motor protection device according to the present invention, showing a state in which the motor protection device is not operated.

4 is a circuit diagram showing an electrical connection state of the motor protection device of FIG.

FIG. 5A illustrates a state in which the first bimetal disk is operated in the motor protection device of FIG. 3. FIG.

5B is a view illustrating a state in which the second bimetal disk is operated in the motor protection device of FIG. 3.

6 is a cross-sectional view of the motor protection device to which the plate-like heating element is applied, similar to FIG. 3;

FIG. 7A is a simplified view showing a state in which the central axes of the contact projections of the bimetal disk and the movable arm are offset from each other; FIG.

FIG. 7B is an enlarged partial view of FIG. 7A.

<Explanation of symbols for the main parts of the drawings>

31: first bimetal member

32: operation arm

32a: fixed contacts

32b: movable contact

32c: turning of operation arm

33: second bimetal member

34,35 connection terminal

37, 38: contact portion of connecting terminal

39,39 ': heating element

In order to achieve the above object, the present invention provides a motor protection device for protecting a motor when an overload is applied to the motor, the base, two connection terminals fixed to the base and connected to the motor side, and detachable from the connection terminal A movable arm that is electrically connected electrically, a first and a second heat sensitive element for releasing the electrical connection with the connecting terminal by moving the movable arm when an overload is applied, and heating for shortening the operating time of the heat sensitive element. And an operating temperature of said first and second thermally sensitive elements is different from each other.

In order to achieve the above another object, the present invention provides a motor protection device for protecting a motor when the motor is overloaded, a base, a connection terminal fixed to the base and connected to the motor side, can be separated from the connection terminal Fast-acting first and second heat-sensitive elements of the cup-type, which move the movable arm to release the electrical connection with the connecting terminal when an overload is applied, and a snap of the heat-sensitive element. A heating element that shortens operating time, wherein the operating temperatures of the first and second thermally sensitive elements are different from each other, and the snap central axis of the thermally sensitive element is in contact with the movable arm when the thermally sensitive element moves the movable arm. It provides a motor protection device, characterized in that offset from the reference axis of the portion of.

According to one embodiment of the invention, the first and second thermally sensitive elements are first and second bimetallic members that snap in response to temperature, and each bimetallic member is a first operating temperature that snaps inverted behind a center. And a second operating temperature which snaps back to its original state.

According to one embodiment of the invention, the first and second bimetallic members have different predetermined predetermined first and second operating temperatures, and the first operating temperature of the second bimetallic member is a first of the first bimetallic member. It is higher than the operating temperature, and the second operating temperature of the second bimetal member is lower than the temperature of the motor protection device when the motor to be protected operates normally.

According to one embodiment of the invention, the center of the movable arm is formed with a projection in contact with the heat sensitive element during operation of the heat-sensitive element, the reference axis of the portion where the heat-sensitive element in contact with the movable arm is the central axis of the protrusion It is characterized by that.

According to one embodiment of the invention, the first operating temperature of the first bimetallic member is between 100 and 160 °, and the first operating temperature of the second bimetallic member is about 40 ° ± than the first operating temperature of the first bimetallic member. 10 ° high, the second operating temperature of the first bimetallic member is 50-80 °, and the second operating temperature of the second bimetallic member is -30 ° ± 10 °.

According to one embodiment of the invention, the second bimetal member is set to operate within 60 seconds when the first bimetal member is not operated above the first operating temperature.

Other objects, advantages and details of the motor protection device of the present invention will become apparent from the detailed description showing the preferred embodiment of the present invention with reference to the following drawings.

Hereinafter, various embodiments of the motor protection device according to the present invention will be described in detail with reference to FIGS. 3-6.

The motor protection device described in the following embodiments, which is shown as an example, is of a kind used for a compressor for use such as an air conditioner. Typically, the motor protection device is installed directly on the outer wall of the body of the compressor.

3 is a cross-sectional view of the motor protection device according to the present invention. According to the drawings, the motor protection device of the present invention includes a switch (S1) for cutting off the current when an overcurrent or overload is applied to the motor. The switch is provided with a base, connecting terminals 34 and 35 fixed to the base and connected to the motor side, a movable arm 32 which is electrically connected to the connecting terminal to be detachable, and a movable arm when an overload is applied. First and second bimetal members 31 and 33, which are heat sensitive elements which move to release the electrical connection with the connection terminals, and a heating element 39 disposed adjacent to the bimetal member.

The movable arm 32 is provided with the fixed contact part 32a and the movable contact part 32b in the both ends, and the hemispherical protrusion 32c in the center lower part. When the motor is normally operated, the fixed contact portion 32a is fixed to the contact portion 37 of the connecting terminal 34, and the movable contact portion 32b is detachably contacted with the contact portion 38 of the other connecting terminal 35. have. When the motor is overloaded, the movable contact portion 32b of the movable arm 32 is disconnected from the contact portion 38 of the connection terminal 35, and the electrical connection between the connection terminals 34 and 35 is disconnected to the motor side. The electricity supply is cut off to protect the motor.

The first and second bimetal members 31 and 33, which are the heat sensitive elements, are concave cup-shaped disc-shaped members, and are snap-inverted at a predetermined temperature in response to an increase in temperature. As used herein, the expression 'snap inversion' refers to a phenomenon in which the center of the concave portion of the bimetal member is reversed and flipped over. The first and second bimetal members 31 and 33 are positioned on the base with the two members superimposed on each other with the concave portions facing downward, and are disposed on the lower side of the movable arm 32. Protruding jaws 34 are formed on both sides of the upper part of the base to settle the bimetal member.

The snap inversion operating temperatures of the first and second bimetal members are different from each other, and are set such that the operating temperature of the second bimetal member 33 is higher than the operating temperature of the first bimetal member 31, so that the temperature rises. The second bimetal member is operated after the first bimetal member is operated. The snap reversal actuated bimetal member snaps back to its original form when it falls below a predetermined temperature.

When the bimetal member disposed below the movable arm 32 is snap-reversed at a predetermined temperature, the bimetal member lifts the movable arm while hitting the projection 32c of the movable arm 32, thereby moving the movable arm. As the contact portion 32b is separated from the contact portion 38 of the connection terminal 35, the electric supply to the motor side is cut off.

The snap reversal operating temperature of the first bimetal member 31 is in the range of approximately 100 to 160 °, which is a temperature at which the motor can be judged to be overloaded when the motor has exceeded the normal operating temperature range. It is a range that varies depending on the characteristics of the insulating film surrounding the insulating film and the surrounding elements such as the capacity of the heating element of the motor protection device, and the reset temperature to return to the original state is lower than the normal operating temperature range of the motor, and is preferably about 50 to It is in the 80 ° range.

The second bimetal member 33 superimposed on the first bimetal member 31 is a member that is secondarily operated when the first bimetal member 31 is not operated at the operating temperature, and the snap reversal operating temperature is the first bimetal member 31. In the case of the member, it is preferable to set the temperature higher than about 40 ° ± 10 °, and the reset temperature is lower than the normal operating temperature of the motor, and preferably about -30 ° ± 10 °.

The temperature setting described above is obtained by repeatedly applying an overcurrent or an overload to various compressors, and is a level capable of appropriately blocking current when an abnormality of the motor occurs due to the overcurrent or overload of the motor.

However, in spite of such proper temperature setting, in the case of a motor protection device normally installed on the outer wall of the compressor, the temperature transmission is delayed by the outer wall of the compressor. The temperature of is already far beyond the proper temperature range, and the motor is burned out.

To prevent this, the motor protection device of the present invention includes a heating element 39 connected to the connection terminal 35 adjacent to the bimetal member.

The heating element 39 is a resistance element that is heated by an overcurrent applied to the motor, and since the heat generated by the overcurrent causes the ambient temperature of the bimetal member to rise in advance, the bimetal member is a bimetal member upon application of overcurrent or overload to the motor. It is possible to rapidly increase the temperature to a temperature above 100 °, which is a proper operating temperature of, thereby assuring rapid operation.

In addition, the heating element 39 increases the degree of freedom in design, which allows the operating temperature difference between the first bimetal member 31 and the second bimetal member 33 to be set relatively large, preferably about 40 ° ± 10 °. Contribute.

Specifically, in the case of a conventional motor protection device employing two overlapping bimetallic members, the second bimetallic member in preparation for the inoperability of the first bimetallic member is operated by the first bimetallic member due to the delay in temperature transfer by the compressor outer wall. It is difficult to make a difference greater than the temperature, so it is set to operate at a temperature of about 5-10 °. However, it is difficult to fabricate a bimetal member operated at such a small temperature difference, which causes a problem in the design of the motor protection device. Since the first bimetal member and the second bimetal member are operated at almost the same temperature range, the current over the second stage is increased. The blocking effect could not be expected and the reliability of operation could not be guaranteed.

However, since the heating element 39 according to the present invention maintains the motor protection device in a preheated state to some extent by the heat generation action due to the overcurrent, even if the operating temperature difference between the first and second bimetal members is increased, the motor Allow the second bimetal member to operate immediately at the proper temperature for protection.

The operation of the motor protection device according to the invention will now be described with reference to FIGS. 5A and 5B.

5A is a diagram illustrating a state in which the first bimetal disk is operated in the motor protection device of FIG. 3, and FIG. 5B is a diagram illustrating a state in which the second bimetal disk is operated in the motor protection device of FIG. 3.

When the overcurrent or overload occurs in the motor to reach the snap inversion operating temperature of the motor protection device, the first bimetal disc 31 is snap inverted to operate, thereby stacking the second bimetal member 33 stacked on the top of the first bimetal member. The second bimetal member hits the projection 32c of the movable arm 32 above it. Thereby, while the movable contact part 32b of the movable arm 32 isolate | separates from the contact part 38 of the connection terminal 35, an electric current is interrupted | blocked. At this time, the operation of the first bimetal member 31 can be performed quickly because the ambient temperature is raised by the preheating of the heating element 39 (see FIG. 5A). The snap inverted first bimetal member is returned to its original state in the range of 50 to 80 degrees.

If the first bimetal member 31 is not operated even at the operating temperature due to a defect, when the motor temperature rises by about 40 ° ± 10 ° above the operating temperature, the second bimetal member 33 is operated by snap reversal operation. The arm 32 is lifted up, thereby cutting off the current supplied to the motor (see FIG. 5B). It is due to the preheating effect of the heating element 39 as in the case of the first bimetal member that the second bimetal member can be operated quickly at an operating temperature having a difference greater than the operating temperature of the first bimetal member. Preferably, the second bimetal member is set to operate within 60 seconds when the first bimetal member does not operate above the operating temperature.

The snap inverted second bimetal member may be returned to its original state at a low temperature of about −30 ° ± 10 °. Therefore, since the second bimetal member does not return to the original state unless the cryogenic environment is created, the second bimetal member is configured such that the second bimetal member is almost never returned to the original state after snap inversion and cutting off the current.

This is because when the abnormality of the motor is cut off, the current supplied to the motor is cut off, and then the temperature of the motor is lowered to some extent without repairing the abnormality of the motor. This is to prevent the configuration.

In the motor protection device of the above-described embodiment, the heating element 39 is a coiled heating element, but a plate type heating element 39 'may be employed, and the motor protection device employing the same is well shown in FIG.

On the other hand, during the snap reversal operation of the bimetal member, the bimetal member hits the projection 32c of the movable arm 32, and the bimetal member may be concavely recessed or damaged by the impact at this time. In this case, even if the bimetal member is snap-inverted due to the concave portion, it may not be in contact with the projection of the movable arm, so that the current cannot be interrupted, and the operating temperature of the bimetal member is increased due to the accumulation of impact due to repeated snap inversion. There is room for change.

In order to prevent this, it is preferable to offset the central axis of the concave cup-shaped bimetal member and the central axis of the projection 32c of the movable arm which the bimetal member contacts the bimetal member upon snap reversal.

7A and 7B show well the state in which the central axes of the projections of the bimetal member and the movable arm are offset from each other.

When the bimetal member snaps inverted to come in contact with the projection 32c of the movable arm, the central axis 33 'of the bimetal member and the central axis 32c' of the projection are offset from each other to form a predetermined distance D. From this, the bimetal member is contacted away from the center of the projection of the movable arm, so that the shock due to snap reversal can be greatly alleviated, thereby preventing damage to the bimetal member and of course ensuring operational reliability.

While the preferred embodiments have been described for the purpose of illustrating the invention, it should be understood that the invention includes various modifications and equivalents of the disclosed embodiments, only some of which have been described above. In particular, the bimetal disc can be designed to change its snap inversion operating temperature or reset temperature for application to the device in need.

According to the above-described configuration, the present invention solves the above-mentioned disadvantages of the prior art, and when the motor is overloaded, the operation time is instantaneously and stably operated without being delayed through the preheating process, It provides a motor protection device that ensures stable operation without being damaged by shock.

Claims (13)

In the motor protection device for protecting the motor when the motor is overloaded, A base, a connecting terminal fixed to the base and connected to the motor side, a movable arm detachably electrically connected to the connecting terminal, and when the overload is applied, the movable arm is moved to release the electrical connection state with the connecting terminal. And a heating element for shortening the operating time of the thermally sensitive element, wherein the operating temperature of the first and second thermally sensitive element is different from each other. The method of claim 1, wherein the first and second thermally sensitive elements are first and second bimetallic members that snap in response to temperature, and each bimetallic member is in turn snapped back to the first operating temperature that is snap inverted behind the center. And a second operating temperature that snaps back to a state. 3. The method of claim 2, wherein the first and second bimetallic members have different predetermined predetermined first and second operating temperatures, wherein the first operating temperature of the second bimetallic member is greater than the first operating temperature of the first bimetallic member. And the second operating temperature of the second bimetal member is lower than the temperature of the motor protection device when the motor to be protected operates normally. The motor protection according to claim 1, wherein a projection is formed at the center of the movable arm in contact with the thermal sensitive element during operation of the thermal sensitive element, and the central axes of the thermal sensitive element and the projection of the movable arm are offset from each other. Device. The method of claim 3, wherein the first operating temperature of the first bimetal member is about 100 to 160 °, and the first operating temperature of the second bimetal member is about 40 ° ± 10 ° than the first operating temperature of the first bimetal member. High, wherein the second operating temperature of the first bimetal member is about 50-80 ° and the second operating temperature of the second bimetal member is -30 ° ± 10 °. 4. The motor protection device of claim 3, wherein the second bimetal member is set to operate within 60 seconds when the first bimetal member is not operated above the first operating temperature. A motor protection device for protecting a motor when an overload is applied to the motor, comprising: a base, a connection terminal fixed to the base and connected to the motor side, a movable arm detachably electrically connected to the connection terminal, and at the time of an overload application And cup-type snap actuated first and second heat sensitive elements for moving the movable arms to release electrical connection with the connection terminals, and heating elements for shortening the snap actuation time of the heat sensitive elements. The operating temperatures of the first and second thermally sensitive elements are different from each other, and the snap central axis of the thermally sensitive element is offset from the central axis of the portion of the movable arm that is in contact when the thermally sensitive element moves the movable arm. Protection device. 8. The method of claim 7, wherein the first and second thermally sensitive elements are first and second bimetallic members snap-actuated in response to a temperature, each of the bimetallic members being in original snap action with the first operating temperature snap-inverted behind the center. And a second operating temperature that snaps back to a state. 9. The method of claim 8, wherein the first and second bimetallic members have different predetermined predetermined first and second operating temperatures, wherein the first operating temperature of the second bimetallic member is greater than the first operating temperature of the first bimetallic member. And the second operating temperature of the second bimetal member is lower than the temperature of the motor protection device when the motor to be protected operates normally. 8. The movable arm of claim 7, wherein a projection is formed at the center of the movable arm in contact with the thermal sensitive element during operation of the thermal sensitive element, and the central axis of the portion of the thermal sensitive element in contact with the movable arm is the central axis of the projection. Motor protection device. The method of claim 9, wherein the first operating temperature of the first bimetal member is about 100 to 160 °, and the first operating temperature of the second bimetal member is about 40 ° ± 10 ° than the first operating temperature of the first bimetal member. High, wherein the second operating temperature of the first bimetal member is about 50-80 ° and the second operating temperature of the second bimetal member is -30 ° ± 10 °. 10. The motor protection apparatus of claim 9, wherein the second bimetal member is set to operate within 60 seconds when the first bimetal member is not operated above the first operating temperature. 8. A motor protection device according to claim 1 or 7, wherein the heating element is coiled or plated.