JPH0315410Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a wiper drive device for driving wipers of automobiles, etc.

Conventionally, a wiper drive device includes a motor that drives the wiper, a switch that operates the motor continuously, a switch that operates the motor intermittently, and a switch that operates in conjunction with the motor when the wiper moves to a predetermined position. A wiper driving device is known that includes an interlock switch for automatically stopping the motor at a fixed position and a time constant circuit that uses a combination of a capacitor and a resistor to control the intermittent time.

A conventional wiper drive device is shown in FIGS. 2 and 3.

The device shown in FIG. 2 is commonly used and is designed to perform intermittent operation by using a transistor Tr ₁ , a transistor Tr ₂ , an electromagnetic coil 21, and a relay 22. Here, the intermittent operation time is determined by the time constant of the capacitor 23 and the resistor 24, but the transistor Tr ₁ , which is currently on, actually switches from on to off when the emitter-base voltage becomes 0.7V or less. It will change. Therefore, as shown in the charging characteristic curve of the capacitor 23 in FIG. 5, when the charging potential reaches aV, the transistor Tr ₁ is turned off.

For this reason, it was possible to lengthen the intermittent time (t ₁ ) even by using a small capacitance capacitor, but on the other hand, if there were variations in the capacitance of the capacitor 23 or disturbances (noise) were introduced during the intermittent time, There is a drawback that the intermittent time (t ₁ ) varies greatly. Furthermore, since the electromagnetic coil 21 and the relay 22 are used, there are disadvantages in that noise enters the radio etc. and the control section becomes large.

The device shown in FIG. 3 uses a thyristor 25 instead of the electromagnetic coil 21 and relay 22 of the device shown in FIG. This eliminates the noise caused by the electromagnetic coil and relay, and the circuit can be made more compact.However, since the intermittent time is determined by the capacitor 23 and resistor 24, the above-mentioned drawback of unstable intermittent time is not solved. .

Furthermore, the device shown in Fig. 4 is
30746, which solves the above-mentioned drawbacks, but the control circuit for the thyristor 26 that controls the operation of the motor M must be provided separately from the illustrated device, so the number of parts increases. However, a new drawback arises in that the device becomes larger and more complicated.

This invention was made to eliminate the above-mentioned drawbacks, and in the conventional wiper drive device described above, the cathode terminal of the Zener diode is connected to the output terminal of the time constant circuit, and the anode terminal of the Zener diode is connected to the transistor. The transistor is connected to the base terminal of the motor, the collector terminal of the transistor is connected to the power supply, and the emitter terminal is connected to the gate terminal of a switching thyristor connected in series with the motor power supply line.

In the above configuration, when the charging voltage of the capacitor forming the time constant becomes larger than the Zener voltage of the Zener diode, current flows to the base of the transistor, the transistor is turned on, and current flows to the gate terminal of the thyristor. Therefore, current flows through the motor only for the time it takes for the motor to rotate once.

Therefore, according to the above configuration, it is possible to operate the wiper motor intermittently without using any relays, and it is also possible to stably and reliably obtain a constant intermittent time without being affected by external disturbances. can.

This invention will be specifically explained below based on drawings showing an example of its implementation.

In FIG. 1, three switches are connected in parallel between the negative terminal of a wiper drive motor M that swings a wiper (not shown) of an automobile, etc., and the ground. When the continuous operation switch 1 of these switches is closed by the driver of the vehicle, a direct current flows through the motor M, and the motor operates continuously. That is, as long as this switch 1 is closed, the wiper continuously moves back and forth. The automatic fixed position stop interlock switch 2 is not operated directly by the driver, but is interlocked with a reduction gear (not shown) of the motor M.
It is opened when the wiper blade is located at a predetermined position (for example, at the lower end of the window). Therefore, even if the driver attempts to stop the wiper by opening the continuous switch 1, if the wiper is not in the predetermined position at that time, the wiper will continue to move, and when the wiper reaches the predetermined position, the switch 2 will be opened. Wipers stop. This fixed position stop function of the switch 2 works in the same way when the intermittent operation switch described below is opened.

Intermittent operation switch 3 that operates the wiper intermittently
is connected between the negative terminal 16 of the motor M and ground via the thyristor 4, and energizes the motor M only when the switch 3 is closed and the thyristor 4 is conductive. Thyristor 4
The capacitor 5 connected in parallel with the thyristor 4 prevents the thyristor 4 from malfunctioning.

A trigger voltage generation circuit for applying a trigger voltage to the gate of the thyristor 4 includes a capacitor 6
, a time constant circuit consisting of resistors 7 and 8 , a Zener diode 13 , and a transistor 14 .

The time constant circuit includes resistors 7 and 8 connected in series between the negative terminal 16 of the motor M and the output terminal 17, and a capacitor 6 connected between the output terminal 17 and the cathode of the thyristor 4. It is formed. Diode 11 connected in parallel with resistor 8
is for discharging the charge stored in the capacitor 6.

Output terminal 17 of the above time constant circuit and transistor 1
A Zener diode 13 is connected between the base of 4 and the base of 4 as shown in the figure. This Zener diode 13 has a predetermined Zener voltage.

The collector of the transistor 14 is connected to the positive side of the power supply, a resistor 9 is connected between the emitter and the cathode of the thyristor 4, and a resistor 10 is connected between the emitter and the gate terminal of the thyristor 4.

A diode 15 connected between the positive terminal of the power supply and the cathode of the thyristor 4 is for preventing destruction of the transistor 14 or the thyristor 4 due to a surge voltage generated across the motor M when the motor M is deenergized. be.

Next, the intermittent operation of the wiper drive device constructed as described above will be described. When the motor M is de-energized, if it were to be turned on by closing the intermittent operation switch 3, the negative terminal 16 of the motor M would be at a high potential and a charge would be stored in the capacitor 6 through the resistors 7 and 8. Ru. Therefore, the voltage generated at the output terminal 17 gradually increases as shown in FIG.
After that, the Zener voltage of the Zener diode 13 is reached.

Thereafter, current begins to flow through the base of transistor 14, turning on transistor 14. As a result, a current flows through the resistor 9 and a voltage is generated, and this voltage is applied to the gate terminal of the thyristor 4 via the resistor 10 as a trigger voltage.

Therefore, a current flows through the gate of the thyristor 4, and the thyristor 4 is rendered conductive, that is, turned on. For this reason, the negative terminal 16 of the motor M is grounded via the thyristor 4 and the intermittent operation switch 3, so that current flows to the motor M and the motor M rotates. When the automatic fixed position stop interlocking switch 2 interlocked with the motor M is turned on by the rotation of the motor M, the voltage between the anode and cathode of the thyristor 4 becomes zero, so the thyristor 4 is turned off.

However, since the interlock switch 2 for automatic fixed position stop is on, the current of the motor M flows through the interlock switch 2 instead of the intermittent switch 3, and the motor M continues to flow until the wiper moves to the next automatic stop position. M starts rotating.

At this time, when the switch 2 is turned on, the charge stored in the capacitor 6 is discharged through the diode 11, the resistor 7, and the switch 2.

Next, when the wiper reaches the automatic stop position, the interlock switch 2 is turned off, so no current flows through the motor M, and the motor M stops. When the motor M stops, the negative terminal of the motor M becomes a high potential again, and as described above, the capacitor 6 is again connected to the capacitor 6 due to the time constant determined by the resistors 7 and 8 and the capacitance of the capacitor 6.
is gradually charged. During this time, the motor M is in a stopped state. When the charging voltage of the capacitor 6 reaches the voltage regulated by the Zener diode 13, the transistor 14 is turned on, a trigger voltage is applied to the gate of the thyristor 4, and the thyristor 4 is turned on. Thereafter, while the motor M rotates and the intermittent switch 3 is turned on, the above operation is repeated, and the wiper linked to the motor M continues to operate intermittently.

That is, the intermittent stop time feeds back the movement of the motor and is controlled from the time of automatic stop to the time of the next start of operation.

When the intermittent switch 3 is turned off, the interlock switch 2 is kept on until the wiper reaches the predetermined position as described above, so the motor M continues to rotate until it reaches the stop position.

Thus, according to the above configuration, since the capacitor 6, the resistor 8, the Zener diode 13, and the transistor 14 are incorporated, the intermittent time can be controlled not only by the time constant of the capacitor 6 and the resistor 8, but also by the Zener voltage of the Zener diode 13. be done. Therefore, in the capacitor charging characteristic curve shown in FIG. 5, even if the operating voltage of the transistor 14 for turning on the thyristor 4 is 0.7V, by changing the Zener voltage,
can be turned on with the voltage at point c. This makes it easier to control the intermittent time, and has the effect of eliminating instability in the intermittent time due to disturbances or variations in the capacitor 6.

Further, even if the transistor 14 is momentarily turned on by the Zener diode 13, the thyristor 4 is kept in the on state, so that the control circuit can be simplified.

As described above, according to this invention, since it is configured as described above, the intermittent operation of the wiper motor can be driven without using a relay, and without being affected by external disturbances. A certain amount of intermittent time can be obtained reliably.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the structure of a wiper drive device according to this invention, FIGS. 2 to 4 are circuit diagrams showing the structure of conventional wiper drive devices, and FIG. 5 is a circuit diagram showing the structure of a wiper drive device according to this invention and the conventional device. 3 is a graph showing a charging characteristic curve of a capacitor of FIG. 1... Continuous switch, 2... Interlocking switch for automatic fixed position stop, 3... Intermittent switch, 4... Thyristor, 5, 6... Capacitor, 7, 8, 9, 1
0... Resistor, 11... Diode, 13... Zener diode, 14... Transistor, 15...
...Diode, M...Motor.

Claims (1)

[Scope of utility model registration request] A motor that drives the wiper, a switch that operates the motor continuously, a switch that operates the motor intermittently, and an automatic switch that operates in conjunction with the motor and turns off the motor when the wiper moves to a predetermined position. An interlocking switch for stopping at a fixed position,
In a wiper drive device comprising a time constant circuit that controls intermittent time by combining a capacitor and a resistor, a cathode terminal of a Zener diode is connected to an output terminal of the time constant circuit, and an anode terminal of the Zener diode is connected to a base of a transistor. A wiper drive device characterized in that the collector terminal of the transistor is connected to a power supply, and the emitter terminal is connected to a gate terminal of a switching thyristor connected in series to a power supply line of a motor.