JPH083067Y2 - Power control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a power supply control device that energizes a load for a certain period of time after a power switch is turned off.

[Conventional technology]

The engine temperature is maintained at 80 ° to 90 ° C during rotation, but rises to around 100 ° C immediately after stopping, and then drops to around 40 ° C for about 30 minutes. The gasoline remaining in the carburetor after the engine is stopped is vaporized due to the high temperature, and the excess of gasoline adversely affects the next engine start. Therefore, after the engine is stopped, the vaporized gasoline in the carburetor is generally guided to the canister through a bypass, where it is liquefied and returned to the tank. The bypass from the carburetor to the canister is opened and closed by an electromagnetic valve,
Since this valve is controlled by a solenoid, it is necessary to supply current from the battery to the solenoid when opening.

In addition to this, there are many devices (data holding memory, etc.) that keep the current active from the battery even after the engine is stopped. Therefore, in order to reduce the current consumption of the battery, the engine temperature drops to around 40 ℃. Then, when the gasoline does not vaporize, the valve opening / closing solenoid (VSV)
It is desirable to stop energization to to prevent unnecessary current consumption (dark current of about 20mA).

[Problems to be solved by the invention]

The present invention intends to meet the above-mentioned demand by configuring a power supply control device that drives a load for a certain period of time after the power switch is turned off and then cuts off its own power supply.

[Means for solving problems]

FIG. 1 is a basic configuration diagram of the present invention. BATT is a backup line directly connected to a battery, + B is a power line connected to the battery through a power switch (in this example, an ignition switch IG SW), 1 is the switch The timer circuit starts when the power is turned off, 2 is its power circuit, 3 is a load drive circuit, and 4 is a load (in this example, a valve opening / closing solenoid).
VSV) and 5 are power cutoff circuits.

[Action]

The power cutoff circuit 5 is the power supply circuit 2 and the backup line BA
You can cut off between TT. Since the timer circuit 1 and the load drive circuit 3 are supplied with power from the power supply circuit 2, when the power cutoff circuit 5 operates, the load 4 is de-energized and the timer circuit 1 consumes no current. Timer circuit 1 is a switch
It starts when the IG SW is turned off. Then, after a predetermined time T, the output is inverted to operate the power cutoff circuit 5. The "input" shown in the frame of the timer circuit 1 in Fig. 1 is IG SW.
Is ON and OFF, and the “output” is a waveform of electricity to the load 4.

〔Example〕

FIG. 2 is a circuit diagram showing an embodiment of the present invention, and symbols of respective parts correspond to those in FIG. Reference numeral 6 is a delay circuit added for the purpose of removing noise when detecting ON / OFF of the ignition switch IG SW. This circuit 6 is IG
When SW is turned on, the capacitor C5 is charged with + B, and when the voltage exceeds a certain value, the transistors TR8 and TR7 are turned on and the output becomes H (high). And IG S
When W is turned off, the electric charge of the capacitor C5 is discharged through the base-emitter of the transistor TR8, and eventually the output becomes L.
Invert to (low). Each of these delay times τ is about 100 ms, which prevents malfunction due to short noise below this.

The output of the delay circuit 6 is branched into three, one of which enters the base of the transistor TR4 of the load driving circuit 3. Therefore,
= H turns on the transistor TR4, turning on the transistor T
Since R3 is off, load 4 is not energized. The second enters the base of transistor TR5 and turns it on with = H. This transistor TR5 is for supplying the base current of the transistor TR1 of the power cutoff circuit 5, so when TR5 is ON, TR
1 is also turned on. The third enters the terminal of the comparator 7. The voltage of the terminal of the comparator 7 is the timer circuit 1
Since it is the reference voltage V _R made by the IC of, the output of the comparator 7 becomes L when = H> V _R. Since this output = L enters the reset terminal RST of the timer circuit 1, the timer circuit 1 is in the reset state. The above is the case where = H, and the waveform (or state) of each part is as shown in FIG.

Next, when the IG SW is turned off, the output of the delay circuit 6 becomes L after a while. Therefore, in the load driving circuit 3, the transistor TR4 is turned off and TR3 is turned on, so that the load 4 is energized. At the same time, the output of comparator 7 is H
When it becomes (open), the timer circuit 1 starts operating.
The timer operation waveform in FIG. 3 shows the change of the oscillation output terminal OSC. Transistor TR even when = L
Since 5 is supplied with the base current through resistors R4 and R5, it does not turn off. Since the output (OUT) is L while the timer circuit 1 is counting, the output of the comparator 8 is H.
Hold, and charge the capacitor C1 for cutoff (for example, if the point is + 5V, TR5 side is ground to TR5 V _BE = 0.7).
Only V is higher).

The above is the state of FIG. 3, and eventually the timer time T
When (for example, 30 seconds) has elapsed, the timer output is inverted to H and the output of the comparator 8 is set to L = 0V. For this reason,
Since the base of transistor TR5 is set to 4.3V lower than that by capacitor C1 to −4.3V, + 5V is set in the path of resistors R4 and R5.
The transistor TR5 can be cut off even if it is pulled up to V. As a result, the transistor TR of the power cutoff circuit 5
Since 1 is turned off, the transistor TR2 of the power supply circuit 2 and the transistor TR3 of the load drive circuit 3 are all turned off (they cannot be kept on). Of course, the operation of the timer circuit 1 also stops. In the subsequent period (Fig. 3), the dark current disappears in this power-off state.

Although the output is not shown in FIG. 3, this is the output of the comparator 7. As is clear from FIG. 2, the output is H, and if it is higher than the reference voltage V _R , the output is L and the output is L. Below V _{R the} output is high. Although the output is also not shown in FIG. 3, this is the output of the comparator 8 and is pulled up by the resistor R4, and the output of the timer circuit 1 is H while the output is L, and the output is H when the timer time T elapses. Becomes L. The input of the timer circuit 1 is an output, which serves as a reset signal for the circuit. The output becomes H when the timer time T elapses after reset release (= H).
The power supply circuit 2 is composed of a transistor TR2 and its base circuit resistor (R) and capacitor (C).
Is turned on, the transistor TR2 is turned on with the RC time constant.

[Effect of device]

As described above, according to the present invention, power is supplied to a load that needs to be operated only for a limited time after the power switch is turned off for a fixed time, and thereafter, not only the load but also its own power is shut off. Therefore, there is an advantage that unnecessary current can be effectively prevented from flowing from the battery for a long time.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is an operation waveform diagram thereof. In the figure, 1 is a timer circuit, 2 is a power supply circuit, 3 is a load drive circuit, 4 is a load, 5 is a power cutoff circuit, IG SW is a power switch, BATT is a backup line, and + B is a power line.

Claims (1)

[Scope of utility model registration request] 1. A power supply control device for supplying a current from a backup line to a load among a backup line directly connected to the battery and a power supply line connected to the battery via a power switch. When a power supply switch is turned off, the power switch is started, and a timer circuit that outputs an output and generates a time-out output after a fixed time and a power cutoff circuit driven by the output of the timer circuit when the power switch is turned off A load drive circuit that is turned on to flow a current to the load, and the power cutoff circuit is inserted in the backup line;
Controlled by the potential of the power supply line and the output of the timer circuit, the power supply switch is turned on when the power switch is turned on, the power switch is turned off, and when the timer circuit produces a time-out output, the timer circuit is turned off. The power supply control device is characterized in that the power supply to the load is cut off and the power supply to the load drive circuit is cut off to stop the current supply to the load.