JPH0138648Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a motor control circuit for a small electric pump used for transferring kerosene or refueling at home, for example.

Small electric pumps are easier to handle than conventional manual siphon pumps, so they are mainly used for kerosene transfer and refueling. FIG. 1 shows an example of this type of small electric pump, in which a self-contained battery B and a pump section 1 driven by an electric motor M are connected between the battery B and the motor M. The intervening power switch S, the liquid level detector 3 attached to the tip of the discharge hose 2 of the pump section 1, and the motor M are driven based on the operating states of the switch S and the detector 3. It is constituted by a motor control circuit 4 for controlling the motor.
This prevents dangers such as so-called overflow.

By the way, as an example is shown in FIG. 2, the conventional motor control circuit 4 first includes the liquid level detector 3 and is connected to the battery B via the power switch S. The driving power inside the circuit 4 is supplied only when the circuit 4 is turned on.

The control circuit 4 also includes a trigger generation circuit 4a that detects a transient state when the switch S is turned on and generates an instantaneous trigger signal, and a trigger generation circuit 4a that generates a continuous trigger signal after the transient state elapses after the switch S is turned on. A delay circuit 4b that generates a signal, a bistable circuit 4c formed by applying direct current positive feedback to a non-inverting direct current amplifier circuit formed by directly connecting two stages of first and second transistors Q1 and Q2, and the above-mentioned a third transistor Q3 which is driven into conduction by the delayed signal and which is driven such that the non-detection output of the liquid level detector 3 bypasses the delayed signal and is forced into the non-conductive state; have. Furthermore, while the trigger signal sets and drives the bistable circuit 4c from one stable state to the other stable state, the conduction state of the third transistor Q3 drives the bistable circuit 4c to the other stable state. The device is configured to forcibly reset the state to a stable state. The motor M is connected as a load to the transistor Q2 at the latter stage of the bistable circuit 4c, and when the bistable circuit 4c is in the other stable state, the motor M is
It is designed to provide driving power to the As a result, when the switch S is turned on and turned on, the motor M is driven and transfer of liquid such as kerosene is started, and the level of the transferred liquid is detected by the liquid level detector 3. When this happens, the drive power of the motor M is automatically cut off, and dangers such as overflow are automatically prevented, and even if the switch S is accidentally forgotten to be turned off, an arbitrary restart is prevented.

However, in the conventional motor control circuit 4 as described above, since the motor M is inside the bistable circuit 4c as shown in FIG. etc., the voltage between the terminals of the motor M may drop momentarily, or a pulse of opposite polarity may appear between the terminals, which causes the bistable circuit described above to 4c
However, when the other stable state should be maintained, the pump is suddenly reset to one stable state, causing a problem in which the pump suddenly stops mid-operation.
In the past, the causes of such troubles were not necessarily understood, and the cause-and-effect relationship was unclear and they occurred randomly, so in the past, it was difficult to take appropriate countermeasures and treatments. There was nothing I could do.

This invention was made based on the above-mentioned issues and knowledge, and its purpose is to solve the abnormal stoppage of the motor M, the cause of which was previously unknown, with a relatively simple additional configuration. Therefore, it is an object of the present invention to provide a motor control circuit for a small electric pump that can reliably prevent such problems.

Hereinafter, embodiments of this invention will be described in detail based on the drawings. FIG. 3 shows an embodiment of a motor control circuit for a small electric pump according to this invention, and in the figure, parts common or corresponding to those of the conventional circuit are given the same reference numerals. In addition, in the following description, differences from the conventional method will be mainly explained.

The motor control circuit 4 shown in the figure is provided in the small electric pump as described above, and first includes a liquid level detector 3, and is connected to a self-contained battery B via a power switch S. . Further, a trigger generation circuit 4a detects a transient state when the power switch S is turned on and generates an instantaneous trigger signal.
and a delay circuit 4b that creates a sustained delay signal after the transient state has passed after the power switch S is turned on.
and a bistable circuit 4c formed by applying DC positive feedback to a non-inverting DC amplifier circuit formed by directly connecting two stages of first and second transistors Q1 and Q2.
and a third circuit which is driven to be conductive by the delayed signal and whose drive is controlled so that the non-detection output of the liquid level detector 3 bypasses the delayed signal and forcibly brings it into a non-conductive state. and a transistor Q3. Furthermore, a fourth transistor Q4 is provided which intervenes in series between the motor M and the power switch S. The trigger signal sets and drives the bistable circuit 4c from one stable state to the other stable state, while the conduction state of the third transistor Q3 causes the bistable circuit 4c to be driven from the other stable state. The device is configured to forcibly reset the state to one of the stable states. Further, the fourth transistor Q4 is driven to be conductive by the other stable state of the bistable circuit 4c, and the drive end of the motor M is controlled by the second stable state of the bistable circuit 4c. It is arranged to be isolated from the stabilizing circuit 4c.
Here, a collector resistor R1 is connected as a load to the second transistor Q2 of the bistable circuit 4c. A portion of the DC output voltage obtained from both ends of the resistor R1 is fed back to the input side via the resistor R2. The first and second transistors Q1 and Q2 of the bistable circuit 4c are directly connected through a resistor R3. The output of the other stable state of the bistable circuit 4c is applied from the transistor Q1 in the preceding stage to the base of the fourth transistor Q4 via the resistor R4.
The trigger generation circuit 4a has a capacitor C1
The differential circuit includes a resistor R5 and a resistor R5.
Further, the delay circuit 4b is composed of resistors R6, R7 and a capacitor C2. A charging current flows into this capacitor C2 via a resistor R7, and a discharging current flows out via a resistor R7 and a resistor R6. The base side of the third transistor Q3 is connected to the delay circuit 4 via a resistor R8. Thereby, the trigger signal can be forcibly bypassed by the non-detection output (ON state) of the liquid level detector 3. The liquid level detector 3 is configured to supply the current obtained through the fourth transistor Q4 to the light emitting diode L through a resistor R9. Then, the light from the light emitting diode L is totally reflected several times within the optical prism 3a to change its direction, and then is made to enter the phototransistor P. This phototransistor P is the third transistor Q3.
are connected in parallel to the base side of the resistor R8 through a resistor R8. Thereby, the trigger signal can be forcibly bypassed by the non-detection output (ON state) of the liquid level detector 3. In this liquid level detector 3, when the level of a liquid such as kerosene rises to a predetermined level, the prism 3a comes into contact with the liquid, and as a result, the relative refractive index of the prism 3a decreases, and the above-mentioned The amount of light incident on the phototransistor P decreases significantly, and as a result, the state between the output terminals of the phototransistor P becomes OFF,
The third transistor Q3 is driven to conduct. At this time, the bistable circuit 4c is forcibly reset driven from the other stable state in which each transistor Q1 and Q2 are both in a conductive state to one stable state in which both transistors Q1 and Q2 are both in a non-conductive state. Ru. Then, the driving power for the motor M is cut off, and the pump immediately stops operating, thereby automatically preventing overflow and the like.

FIG. 4 shows another embodiment of this invention, and the difference from the embodiment shown in FIG.
The transistor Q4 is driven into conduction by the transistor Q2 at the subsequent stage of the bistable circuit 4c. In this case as well, it can operate in the same way as the one in FIG.

Now, in the motor control circuit configured as described above, the drive current of the motor M for operating the pump is controlled to be conductive by the bistable circuit 4c rather than from the transistor in the bistable circuit 4c. Since the power is supplied through the fourth transistor Q4, the drive end of the motor M and the bistable circuit 4c are temporarily isolated. As a result, even if the voltage between the drive terminals of the motor M drops momentarily or a reverse polarity pulse appears there, the effect of this can be reduced by the method described above.
Therefore, the bistable circuit 4c can reliably maintain a stable state determined based on the operating states of the power switch S and the liquid level detector 3, thereby reducing the risk of malfunction. disappears. Therefore, even if an abnormal load is applied to the motor M, a failure such as an abnormal stop of the operating pump will not occur.

As described above, the motor control circuit for a small electric pump according to the present invention can reliably prevent abnormal stoppage of the motor, the cause of which was unknown in the past, with a simple additional configuration.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an example of a small electric pump.
FIG. 2 is a circuit diagram showing an example of a conventional motor control circuit, FIG. 3 is a circuit diagram showing one embodiment of the motor control circuit according to this invention, and FIG. 4 is a circuit diagram showing another embodiment. B...Self-contained battery, M...Electric motor, S...Switch, 3...Liquid level detector, 4...Motor control circuit, 4a...Trigger generation circuit, 4b...Delay circuit, 4c...2 Stabilization circuit, Q4...the fourth transistor.

Claims (1)

[Claims for Utility Model Registration] The pump includes a self-contained battery B, an electric motor M, a pump, a power switch S, a liquid level detector 3, and a control circuit 4, and the pump is driven by the electric motor M. The power switch S is interposed between the battery B and the motor M, the liquid level detector 3 is attached to the tip of the discharge hose of the pump, and the control circuit 4 is connected to the liquid level. In a motor control circuit for a small electric pump that controls the drive of the motor M according to the on/off state of the detector 3, the control circuit 4 includes a trigger generation circuit 4a;
It has a delay circuit 4b, a bistable circuit 4c, a third transistor Q3, and a fourth transistor Q4, the bistable circuit 4c has first and second transistors Q1 and Q2, and the trigger The generation circuit 4a detects the transient state when the power switch S is turned on and generates an instantaneous trigger signal, and the delay circuit 4b continues to generate the delayed signal after the transient state after the power switch S is turned on has passed. the first and second transistors Q1 and Q2;
consists of a non-inverting DC amplifier circuit with DC positive feedback, and has two stable states, which are set from one stable state to the other by the trigger signal, and set to the other stable state by driving the third transistor Q3. is reset to one stable state from The fourth transistor Q4 is conductive when the bistable circuit 4c is set and non-conductive when the bistable circuit 4c is reset, and the delay circuit 4b and the bistable circuit 4c are connected in series. The trigger generation circuit 4a is connected between the battery B and the input side of the bistable circuit 4c, and the third transistor Q3 is connected in parallel between the battery B and the power switch S. Delay circuit 4
b and the input side of the bistable circuit 4c, the light emitting side of the liquid level detector 3 is connected in parallel to the motor M, and the light receiving side is connected to the delay circuit 4.
The motor M and the fourth transistor Q4 are connected in series, and this is connected between the battery B and the power switch S.
A motor control circuit for a small electric pump characterized by a parallel connection between the motor control circuit and the motor control circuit for a small electric pump.