JPH0411676Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a safety device for dryers used in general households.

BACKGROUND ART Conventionally, as shown in FIG. 2, this type of dryer safety device reads the output signal of an AC voltage zero point detection circuit 11 into an electronic time control device 12, performs time control, etc., and then A motor drive signal and a heater drive signal were output, the three-terminal control rectifier 13 was operated, and the motor 14 and heater 15 were energized and operated. When the electric motor 14 becomes locked during operation of the dryer, the heater 15 generates abnormal heat and the temperature fuse 16 is blown as a general safety measure.

Problems that the invention attempts to solve: However, even if the factors that cause the electric motor 14 to be in a restrained state are removed, it becomes impossible to continue operation again.
Another problem was that if an abnormality occurred in the electronic time control device 12, the safety device would become inoperable.

The present invention solves these conventional problems, and allows operation to be resumed immediately after the motor is released from the restraint state.Furthermore, even if an abnormality occurs in the control device, it can operate safely. The purpose is to provide a highly reliable safety device for dryers.

Means for Solving the Problems In order to solve the above problems, the present invention includes an AC voltage zero point detection circuit that generates a time reference signal, and a circuit that inputs the above reference signal and uses this signal as a reference to set the time of the dryer. an electronic time control device that controls and outputs a motor drive signal and a heater drive signal, and a three-terminal control rectifier that controls energization of the motor and heater using signals from the electronic time control device;
A detection means for detecting whether the electric motor is in a rotating state or a locked state by a voltage generated between the auxiliary windings of the motor, and a logic between the locked state detection signal of the detection means and the heater drive signal of the electronic time control device. and means for cutting off the three-terminal control rectifying element corresponding to the heater when the detecting means detects the locked state of the electric motor.

Operation With the above configuration, the voltage generated in the auxiliary winding after the motor is energized is detected to confirm the restraint state of the motor, and then the logical product of this restraint state detection signal and the heater drive signal is taken, and the three-terminal control rectification is performed. Operates the element and stops power supply to the heater to prevent abnormal heating of the heater. Furthermore, once the factor that causes the motor to be in a restricted state is removed, the operation can be resumed immediately.

Embodiment An embodiment of the present invention will be described below based on the drawings. FIG. 1 is a circuit diagram of a safety device showing an embodiment of the present invention. In FIG. 1, reference numeral 1 indicates an AC voltage zero point detection circuit, which converts a full-wave rectified waveform into a pulse waveform using a transistor and a resistor. Reference numeral 2 denotes an electronic time control device, which outputs a motor drive signal and a heater drive signal for controlling the time limit of a dryer (not shown) based on the output signal of the AC voltage zero point detection circuit 1. Reference numeral 3 indicates a three-terminal control rectifier element, which controls energization of the motor 4 and heater 9. Reference numeral 5 indicates a light emitting element, 6 a light receiving element, and 7 a voltage comparator. These light emitting and light receiving elements 5 and 6 and the voltage comparator 7 determine whether the motor 4 is in a rotating state or a locked state. A detection means is configured to detect the voltage generated between the lines. Reference numeral 8 denotes an AND circuit, which is means for cutting off the three-terminal control rectifying element 3 corresponding to the heater 9 when the detecting means detects that the electric motor 4 is in a restrained state.

The operation of the above configuration will be explained. A pulse wave synchronized with the AC power frequency generated in the AC voltage zero point detection circuit 1 is used as a time reference signal,
It is input to the electronic time control device 2 to control the time of the entire dryer. The electronic time control device 2 performs time control and then outputs a motor drive signal and a heater drive signal. The motor drive signal and the heater drive signal operate the three-terminal control rectifying element 3 to energize the motor 4 and heater 9 to enter a drying operation.

Whether the electric motor 4 is in a rotating state or in a locked state is determined by the motor 4.
This can be recognized by checking the voltage between the auxiliary windings. In FIG. 1, the voltage between the auxiliary windings causes the light-emitting element 5 to emit light, the light-receiving element 6 receives the light, and the voltage comparator 7 compares the output voltage of the light-receiving element 6 with a reference voltage for determination. If the electric motor 4 reaches a locked state for some reason during drying operation of the dryer, if the power to the heater 9 is not immediately stopped, abnormal heating of the heater 9 will cause a safety problem. 7 generates an output signal, the AND circuit 8 is inhibited, and the operation of the three-terminal control rectifying element 3 is stopped, thereby blocking power supply to the heater 9 and preventing abnormal heating of the heater 9. There is. Furthermore, when the factor restraining the electric motor 4 is removed and the electric motor 4 starts rotating normally, the output signal of the voltage comparator 7 is inverted, so the AND circuit 8 enters the pass state, and the three-terminal control rectifier 3 Then, the heater 9 is started to be energized and the drying operation is continued.

In this way, when the electric motor 4 is rotating normally, normal drying operation is continued, and when the electric motor 4 reaches a locked state, the power supply to the heater 9 is blocked to prevent abnormal heating of the heater 9. becomes possible.

Effects of the invention As described above, according to the invention, there is provided an electronic time control device, an AC voltage zero point detection circuit, a three-terminal control rectifier, a heater, an electric motor, a detection means, and a three-terminal control corresponding to the heater. It detects whether the motor rotates normally or is in a locked state using the voltage generated between the auxiliary windings of the motor, and when the locked state is detected, the locked state is detected. Take the logical product of the signal and the heater drive signal,
Since it prevents electricity from flowing to the heater, it prevents the heater from overheating, and once the factor that restrains the motor is removed, it can immediately resume operation, making it an inexpensive safety device for dryers. be. Furthermore, safety does not depend on the electronic time control device, and even if an abnormality occurs in the electronic time control device, it can operate safely and prevent energization to the heater. Furthermore, since a three-terminal control rectifier element is used as the heater's energization/cutoff means, it is more reliable and can be provided at a lower cost than mechanical contact systems.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a safety device for a dryer showing an embodiment of the present invention, and FIG. 2 is a conventional circuit diagram. 1... AC voltage zero point detection circuit, 2... Electronic time control device, 3... Three-terminal control rectifier, 4...
Electric motor, 5... Light emitting element, 6... Light receiving element, 7...
...Voltage comparator, 8...AND circuit, 9...heater.

Claims (1)

[Scope of utility model registration request] an AC voltage zero point detection circuit that generates a time reference signal, and an electronic time control device that inputs the reference signal, controls the dryer time using this signal as a reference, and outputs a motor drive signal and a heater drive signal. , a three-terminal control rectifying element that controls energization of the motor and heater in response to a signal from the electronic time control device, and a voltage generated between the auxiliary windings of the motor to determine whether the motor is rotating or locked. A logical product is taken between the detecting means to detect, the restrained state detection signal of the detecting means, and the heater drive signal of the electronic time control device, and when the detecting means detects the restrained state of the electric motor, the controller responds to the heater. A safety device for a dryer, comprising means for interrupting the three-terminal control rectifying element.