Safety type thermal overload protector (multifunctional motor bimetal protector):
The newly invented safety thermal overload protection switch involves: A built-in overload protection device and PTC heating element. Thermal overload protector with multiple protection functions of current overload self-locking and overheating self-locking. It is suitable for rotating motor protection applications such as juice motor, soybean milk machine motor, water pump motor, vacuum cleaner motor, power tool, etc.

Technical Design:
At present, the common motor protectors are overheat protectors or overload protectors. The principle of the overheat protector is:
When the thermal overload protector reaches the rated take-off temperature of the bimetallic element inside the thermal protector through the induction motor's medium temperature, the bimetallic element acts to cut off the current passing through the motor coil and stop the motor; When the temperature of the medium around the protector drops to the rated reset temperature value of the bimetal element, the bimetal element resets, and the motor current is turned on again to make it work. In this way, the motor is in the cycle of heating/off→cooling/on.
The principle of the overload protector is: The abnormal increase of the current through the thermal overload protector causes the bimetallic element to heat up, cut off the current through the motor coil, and stop the motor;

From the above, the thermal protector belongs to the temperature protection type, and cannot sensitively protect the damage caused by the instantaneous increase of the current when the motor is locked;
The overload protector is usually an external type, which is not only large in size and high in installation cost, but also cannot protect the motor from a slow rise in temperature.

Therefore, the existing motor manufacturers have to use the thermal protector and the overload protector in series at the same time in order to have higher safety of the motor. Although it suffers from the actual pain of complicated installation and high cost, it still cannot completely solve the safety problem of the motor.

invention
The purpose of the present invention is to provide a new type of multifunctional motor protector in view of the above-mentioned shortcomings. It is a kind of built-in overload heating device and PTC heating element. Safety multifunctional motor protector with predetermined overload and overheat protection. The predetermined overload heating device is sensitive to overheating protection at the same time it is more sensitive to overload protection. The added PTC heating element is transferred to the bimetal element with a constant heating temperature after the bimetal element is activated. The patented multifunctional motor protector of the present invention solves the above-mentioned shortcomings and at the same time increases the protection functions of overload self-locking and overheating self-locking. Thereby ensuring the absolute safety of the electrical equipment of the protected motor.


The multifunctional motor protector is realized by adopting the following technical solutions:
Multifunctional motor protector includes shell, fixed seat, PTC heating element, moving contact, static contact, bimetal element, static contact piece, conductive piece, adjusting board, left terminal and right terminal;
The middle end of the right terminal is provided with a bimetal element welding spot, and the other end is provided with an elastic conductive sheet contacting the PTC heating element. One end of the left terminal is provided with a welding boss of an overload heating device, and the other end of the left terminal is connected with one end of the conductive sheet. The other end of the conductive sheet is connected with the static contact sheet, and one end of the static contact sheet is provided with a welding boss of a heating device. The other end of the static contact piece is provided with an elastic conductive piece in contact with the PTC heating element, and one end of the adjusting plate is provided with a welding boss; The static contact piece, the conductive piece, the left terminal and the right terminal are preset in the fixing seat at the same time. The fixed seat is provided with a static contact socket, an overload heating device socket, a PTC heating element socket, a bimetal element, and a placement groove for the adjusting plate. Shell fixing grooves are provided on the left and right sides of the outer edge of the fixing base to form a fixing base assembly; The static contact is placed in the static contact socket set on the fixed seat and welded with the static contact piece. The bimetal element assembly is placed in the bimetal element placement groove of the fixing base assembly, and is welded to the bimetal element welding spot provided at the middle end of the right terminal. The adjusting plate is placed in the adjusting plate placement groove of the fixed seat assembly, and the welding boss provided at one end of the adjusting plate is welded again. The PTC heating element is placed in the PTC heating element socket of the fixed seat to form a multifunctional motor protector assembly. Put the multifunctional motor protector assembly on the shell and fix it.

According to the power of the protected motor and the field of use of the motor, you can choose to cut off the conductive sheet and bridge the overload heating device with the corresponding technical parameters. The overload heating device is placed directly under the bimetallic element, which can make the bimetallic element quickly sense the heating temperature of the overload heating device. The overload heating device is an electric heating wire or an electric heating plate or other heating elements or materials. The overload heating device can be adjusted in a wider range according to the different material cross-sectional area and resistivity. Therefore, the patented multifunctional motor protector of the present invention is suitable for motor protection in almost all fields.

Working principle of multifunctional motor protector:
The bimetal element of the multifunctional motor protector of the invention is connected in series with the overload heating device through the contact and the PTC in parallel. When the motor temperature rises too high, the bimetal element will act and the contact will open, and the PTC will begin to heat up. The bimetal element has been kept in the disconnected state, so that it has the function of self-locking protection against overheating; When the motor current increases abnormally, the overload heating device quickly heats up to make the bimetallic element act, the contact opens, and the PTC starts to heat up. The bimetal element has been kept disconnected, so that it has the function of overload disconnection and self-locking protection.

The patented multifunctional motor protector of the invention has reasonable design and compact structure, and is a brand-new motor overload protector. Has a wider application field and more reliable safety performance. It can be widely used in electric motors, rotating electric machines of household appliances, household electric heating appliances, lighting appliances, communication equipment, electronic instruments, meters and other fields that require overload and overheating self-locking protection.