JPH0325639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement of a control device for an electric fan, thereby improving the safety of the electric fan.

Conventional technology Conventionally, when a person approaches or touches the blade guard of an electric fan, a detection signal is used to cause a direct current to flow through the motor for a certain period of time to quickly stop the motor, even if a finger or the like enters the blade guard. There is now a device that eliminates injuries caused by feathers.

Problems to be Solved by the Invention However, the function of this conventional device only worked when the electric fan was rotating with voltage applied to it, and did not work when the motor was rotating due to inertia. . Even conventional electric fans with plastic blades are “strong”
When rotating, even after the power is turned off, the
The motor continued to rotate due to inertia for 10 seconds.

Furthermore, in recent years, some electric fans have changed their blades from plastic to metal, and others are equipped with electronic circuits that apply voltage to the motor intermittently to create a "natural wind" system that changes the strength of the fan's wind. is also appearing. In this case, the voltage application time to the motor is approximately 4 to 10 seconds, and the stopping time is approximately the same. In other words, the blade rotates due to inertia for 4 to 10 seconds during the stop time, and in the conventional motor, even if a finger is inserted into the blade guard during this period, the motor will not suddenly stop. In other words, half of the driving time is dangerous time without sudden stops like this. Furthermore, since the aforementioned metal blades are heavier than plastic blades, they continue to rotate due to inertia for a longer period of time than plastic blades even after the power is turned off, making them more dangerous.

The present invention solves the above-mentioned conventional problems, and even when the fan blades are rotating due to inertia,
To provide a control device for an electric fan that immediately stops a motor when a person approaches or touches a blade guard, thereby causing no danger to the user.

Means for Solving the Problems In order to solve the above problems, the present invention provides a stop mechanism that suddenly stops the motor that rotates the blades by passing a direct current through the motor, and a stop mechanism that suddenly stops the motor that rotates the blades. The motor has a detection circuit for detecting the approach, a determination circuit for receiving a signal from the detection circuit and operating the stop mechanism, a timer circuit provided in the determination circuit, and a switch for controlling the operation of the motor. switch is OFF
The timer circuit continues to energize the determination circuit for a time approximately equal to the inertial rotation time of the motor, and enables the detection circuit, the determination circuit, and the stop mechanism to operate during this time. have.

Effect With this configuration, the switch is turned OFF,
Even if the power to the motor is stopped, the timer circuit continues to energize the determination circuit for a time approximately equal to the motor's inertial rotation time, so the detection circuit detects the user's When the approach to the blade guard is detected, the motor can be stopped suddenly using the stop mechanism.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a circuit block diagram showing one embodiment of the present invention, where 10 is a fan blade guard and 11 is a motor. Reference numeral 12 denotes a switch for the electric fan main body 20, the details of which are shown in FIG. 2. Turning the switch 12 on and off supplies or stops voltage to the electric fan motor 11. Reference numeral 13 is a detection circuit that detects when a user approaches or contacts the blade guard.There are currently various methods, but in most cases, a high impedance wire is passed through the blade guard 10 and connected to a part of the power supply, and the ground capacitance of the user is detected. Most of them amplify the minute current flowing through the sensor and use it as a detection signal. 1
Reference numeral 4 denotes a determination circuit that manages the time for flowing DC current to the motor 11 based on a signal from the detection circuit 13, and its main role is to control the timing for flowing DC current to the motor 11. 15 is a contact of a relay operated by the judgment circuit 14, which is a common c normally open contact a;
Consists of normally closed contact b. 16 is a power source that supplies DC current to the motor 11.

17 is a relay operated simultaneously by the switch 12 of the main body 20, and 18 is a normally open contact of the relay 17. Next, to explain Figure 2, 19
The power source is the same as the explanation in FIG. 1. Next, the operation of the circuit of this embodiment will be explained.

In normal use, when the switch 12 is pressed on, voltage is applied to the motor 11 from the power source 19, causing the electric fan to rotate. At the same time, the relay 17 is also energized and the normally open contact 18 is closed. Further, by pushing the switch 12, the contact of the switch 12 is released, the motor 11 is stopped, and at the same time, the excitation of the relay 17 is released and the contact 18 is opened. This operation is relay 17
Other than this, it is the same as a normal electric fan, but to make the explanation easier to understand, the fan's air volume adjustment (strong wind, weak wind, etc.) is omitted, and it is simply turned on and off. Next, when the motor 11 is rotating, the blade guard 10
When approaching or touching, a signal is sent from the detection circuit 13 to the determination circuit 14 based on the principle described above. The decision circuit 14 then moves the relay contact 15 from the normally closed contact b to the normally open contact a.
As a result, the motor 11, which until now had been supplied with alternating current from the power supply 19 through the fan switch 12, is now supplied with direct current from the direct current power supply 16, and the motor 11 rapidly stops. However, when direct current is applied to a single-phase induction motor commonly used in electric fans, the impedance of the motor coil becomes only the direct current component, causing the current value to rise, leading to burnout of the motor. Therefore, the DC current is approximately 1
Normally, the current is turned on for only a second, and then the current is not turned on continuously. When the signal from the detection circuit 13 no longer enters the determination circuit 14 after the stop, the relay contact 15 shifts from the normally open contact a to the normally closed contact b. By the way, if the electric fan is currently operating and is turned off by the switch 12, in the conventional electric fan, the detection circuit 1
3 and the determination circuit 14 are also cut off, the electric fan will not stop even if it approaches or contacts the blade guard 10 during the above-described coasting operation. However, in this embodiment, even if the power supply to the motor 11 is cut off by the switch 12, the power supply to the detection circuit 13, determination circuit 14, and DC current power supply 16 is not cut off, so that the functions of each circuit are maintained. Furthermore, switch 12
The contact 18 of the relay 17 driven by the judgment circuit 1
4, the determination circuit 14 is provided with a timer circuit 14a that measures the time after this relay contact becomes open, and if the time is set to 10 to 20 seconds, alternating current is supplied to the fan. During the time corresponding to the inertia operation time after the vane guard 10 is exhausted, the judgment circuit 14 when approaching or touching the blade guard 10
By the action of , the relay contact 15 can be moved to the normally open side a and a sudden stop can be made. Also, since the determination circuit 14 is equipped with a timer circuit, the moment it is thought that the electric fan has completely stopped, the determination circuit 14 will no longer accept the signal from the detection circuit 13, so even though the electric fan has completely stopped, the DC There is no need to cause a stop operation by flowing current.

Effects of the Invention As described above, according to the present invention, even if the electric fan repeatedly operates intermittently, or even if the blades are made of metal or plastic, even if the electric fan is large, the power to the electric fan is turned off. Even in the case where the blades rotate for a very long time due to inertia, it is possible to make a sudden stop operation, and the effect of greatly improving the safety of the electric fan for the user is exhibited.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a drive control circuit for an induction motor according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the switch section in detail. 10...Blade guard, 11...Motor, 13...
...detection circuit, 14...determination circuit, 14a...timer circuit, 16...DC power supply, 19...power supply.

Claims (1)

[Claims] 1. A stop mechanism that suddenly stops the motor that rotates the blade by passing a direct current through the motor, a detection circuit that detects when the user touches or approaches the blade guard, and a detection circuit that receives the signal from this detection circuit. It has a determination circuit that operates the stop mechanism, a timer circuit provided in the determination circuit, and a switch that controls the operation of the motor, and after the switch is turned off, the timer circuit causes the motor to rotate by inertia. A control device for an electric fan that continues to energize the determination circuit for a time substantially equal to the current time, and enables the detection circuit, the determination circuit, and the stop mechanism to operate within this time.