JPH0316514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an automatic stop device for an electric pump.

Conventional configuration and its problems In conventional automatic stop devices for electric pumps, the electric pump was started by turning on the power switch, but the motor that drives the electric pump If the power switch was left on after the automatic shutdown, the battery would discharge and become unusable. Therefore, it was necessary to turn off the power switch after the motor automatically stopped.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
Even if you do not turn off the power switch each time after the liquid level detection device operates and automatically stops the liquid supply, the battery will not be exhausted, and the user will not be able to avoid misuse, e.g. Even if you keep pressing the on switch, it will automatically stop if the liquid level detection device is activated, and even if the liquid level detection device is subsequently pulled out of the liquid, the motor for driving the electric pump will remain stopped, and both the on and off switch will stop automatically. To provide an automatic stop device for an electric pump that always operates on the safe side by stopping the motor even when is pressed.

Structure of the Invention In order to achieve the above object, the present invention provides a liquid level detection device comprising a light emitting element and a light receiving element incorporated in a prism, a flip-flop, and a reset circuit that provides a reset signal to the flip-flop using the output of the light receiving element. , an output circuit that controls an electric pump drive motor based on the state of the flip-flop, and an automatic return type on/off switch that starts and stops the motor, and the flip-flop and other functions are effectively controlled. By combining these functions, it is easy to use and the motor can be reliably stopped even in case of misuse.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In the figure, A is a liquid level detection device,
This liquid level detection device A is constructed by incorporating a light emitting diode 2 as a light emitting element and a light receiving phototransistor 3 as a light receiving element into a prism 1. 4 and 5 are flip-flop transistors; 6 is a resistor connected to the base of transistor 4; 7 is a resistor connected to the base of transistor 5; 8 is an output transistor; 9 is a resistor connected to the base of output transistor 8; 10 is a reset transistor; 11 is a resistor connected to the base of the reset transistor 10; 12 is a delay capacitor; 13 and 14 are resistors connected to the emitter of the light receiving phototransistor 3;
16 is a power-on reset capacitor; 16 is an automatic reset type on switch that sets and operates the flip-flop transistors 4 and 5; 17 is an automatic reset type off switch that resets the flip-flop transistors 4 and 5;
19 is a resistor connected in series with the on-switch 16; 20 is a noise absorbing capacitor connected in parallel with the motor 18; 21 is a current limiting resistor; 22 is the base of the transistor 5. - The resistor 23 connected between the emitters is a battery connected in series with the on switch 16 and off switch 17.

The operation in the above circuit configuration will be explained. Now, when the liquid level has not reached the predetermined liquid level, the light from the light emitting diode 2 is reflected by the prism 1 and enters the light receiving phototransistor 3. As a result, the light receiving phototransistor 3 is turned on. When the liquid level reaches a predetermined level and the prism 1 is submerged in the liquid, the light from the light emitting diode 2 is diffused into the liquid, so almost no light enters the phototransistor 3 for light reception, and as a result, the light reception The phototransistor 3 is turned off. Note that the transistor 4, transistor 5, resistor 6, and resistor 7 constitute a flip-flop, and this flip-flop is turned on or off. The output transistor 8 and the resistor 9 constitute an output circuit, and when the flip-flop transistor 4 is turned on, the motor 18 and the light emitting diode 2 are driven. In addition, the reset transistor 10, the resistor 11, and the delay capacitor 1
2. Resistors 13 and 14 constitute a reset circuit, and when the light receiving phototransistor 3 is on, the voltage of the delay capacitor 12 is close to zero volts, and the reset transistor 10 is turned off. When the light receiving phototransistor 3 is turned off, the base current of the reset transistor 10 flows through the resistor 11.
and flows through the resistor 14, so that the reset transistor 10 is turned on and at the same time, the flip-flop transistor 4 is turned off and the flip-flop is turned off. The power-on reset capacitor 15 is provided to ensure that the flip-flop is turned off when the power is turned on. The on switch 16 is used when starting the motor 18, and turns on the flip-flop transistors 4 and 5 when turned on instantaneously.
The off switch 17 is used to manually stop the motor 18, and when turned on instantaneously, the base current of the reset transistor 10 is changed to the resistor 11,
Since the current flows through off switch 17, reset transistor 10 is turned on and flip-flop transistors 4 and 5 are turned off. This turns off the output transistor 8, so the motor 18 stops.

Now, assuming that the power is turned on and the flip-flop is off, the charge in the delay capacitor 12 is discharged through the resistors 14 and 19, so
The emitter-base voltage of the reset transistor 10 is zero volts. At this time, flip-flop transistors 4 and 5, output transistor 8, on switch 16, and off switch 17 are all off, so almost no power supply current flows. When the on switch 16 is turned on in this state, the base current of the flip-flop transistor 4 flows through the resistor 6, so that at the same time as the flip-flop transistor 4 is turned on, the transistor 5 is also turned on and the flip-flop is turned on. When the flip-flop transistor 4 is turned on, the output transistor 8 is turned on, and the motor 18 and the light emitting diode 2 are driven. At this time, the delay capacitor 12 is charged through the resistor 14, but the on-switch 1
Assuming that the light emitting diode 2 starts emitting light immediately after turning on the reset transistor 1, the light receiving phototransistor 3 turns on and the resistor 13 prevents the delay capacitor 12 from being charged.
0 remains off. As a result, the flip-flop and output transistor 8 remain on, and the motor 18 rotates. In this state, when the liquid level reaches a predetermined level and the prism 1 is immersed in the liquid, the light from the light emitting diode 2 is diffused into the liquid, so the light receiving phototransistor 3 is turned off. As a result, the delay capacitor 12 is charged through the resistor 14 and the flip-flop transistor 5, and the potential between the base and emitter of the reset transistor 10 rises, turning the reset transistor 10 on. This turns off the flip-flop, turns off output transistor 8, and stops motor 18.

Next, the operation in the case of abnormal use will be explained. Now, if the on switch 16 and the off switch 17 are turned on, the base current of the reset transistor 10 flows through the resistor 11 and the off switch 17, so the reset transistor 10 is turned on. As a result, flip-flop transistor 4 and output transistor 8
is turned off and the motor 18 is stopped. Further, when the on switch 16 is turned on continuously, when the light receiving phototransistor 3 is turned off, the delay capacitor 12 is charged through the resistor 14 and the on switch 16, and the reset transistor 10 is turned on. As a result, the flip-flop transistor 4 and the output transistor 8 are turned off, and even if the on switch 16 is kept pressed, the motor 18 is stopped when the predetermined liquid level is reached. Further, when the liquid level detection device A is taken out from the liquid while the motor is stopped, the light emitting diode 2 stops emitting light, the light receiving phototransistor 3 remains off, and the motor 18 continues to stop. When the on switch 16 is turned off in this state, the delay capacitor 12 is discharged via the resistor 14 and the resistor 19, so that it can be returned to its initial state.

Effects of the Invention As described above, according to the present invention, the on-switch that starts the pump drive motor is of an automatic return type, so that when the liquid level reaches a predetermined level, the liquid level detection device automatically starts the pump drive motor. When the power switch is stopped, the on switch connected in series with the battery is turned off, which prevents the battery from draining. It is easier to use as there is no need to turn it off each time, and the pump drive motor can be reliably stopped in case of misuse due to the effective combination of the flip-flop and other functions. It has the following.

[Brief explanation of the drawing]

The figure is an electric circuit diagram of an automatic stop device for an electric pump according to an embodiment of the present invention. A...Liquid level detection device, 1...Prism, 2...
Light-emitting diode (light-emitting element), 3... phototransistor for light reception (light-receiving element), 4, 5... transistor for flip-flop, 8... output transistor, 10... transistor for reset, 12...
...Delay capacitor, 16...On switch, 1
7...Off switch, 18...Electric pump drive motor, 23...Battery.

Claims (1)

[Claims] 1. A liquid level detection device consisting of a light emitting element and a light receiving element built into a prism, a flip-flop, a reset circuit that provides a reset signal to the flip-flop based on the output of the light receiving element, and a motor for driving an electric pump depending on the state of the flip-flop. The light-emitting element is driven by the output circuit, and includes an output circuit for controlling, an automatic reset type on switch for setting the flip-flop, a battery connected in series with the on switch, and an automatic reset type off switch for resetting the flip-flop. Also, an automatic stop device for an electric pump configured such that the reset circuit is inoperative immediately after the on-switch is turned on, and when the on-switch is turned on continuously, the reset circuit is activated by the output of the light receiving element and the flip-flop can be reset.