JPS6021880Y2 - Intermittent wiper device to prevent relay contact welding - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intermittent wiper device that prevents welding of relay contacts.

The intermittent wiper device allows the wiper to perform a wiping operation periodically during times of light rain, etc. by simply turning on the intermittent switch.

Conventionally, one such device utilizes astable multi-by-break oscillation as shown in FIG.

In FIG. 1, M is a wiper motor, one end of which is grounded and the other end connected to a wiper switch WS.

The wiper switch WS is used to stop the wiper motor M (hereinafter referred to as OF
F), intermittent operation (hereinafter referred to as INT), and low-speed continuous operation (hereinafter referred to as LOW).

For this purpose, the wiper switch WS is connected to the battery B via the switch field, to the movable contact COM, or to the ground E.
are connected to each.

One contact NO connected to the movable contact COM is connected to the battery B, and the other contact NC is connected to the movable piece of the automatic fixed position stop device of the wiper motor M, and the movable piece O
is connected to one end of the wiper motor via contact P at the stop position, and to battery B via contact Q at other positions.

A transistor Tr3 is connected in series with the relay RL having a movable contact COM, and the O of this transistor Tr3 is
Relay RL is driven by N and switches movable contact COM from contact NC to contact NO.

Transistors Trl and Tr2, capacitors C2 and C3, and resistor R1 are connected between the base and the transistor of transistor Tr3.
- An astable multivibrator consisting of R2, R3, and R4 is connected to the ground side Hawaii pass switch WS of the astable multivibrator.

Next, the operation will be explained.

After closing the switch BS such as the key switch, when the wiper switch WS is set to LOW, battery B → switch BS
, a current flows from the wiper switch WS to the wiper motor M, and the wiper motor M operates.

When the wiper motor M operates, the movable piece O of the automatic fixed position stop device switches to the contact Q, turning the wiper switch WS OFF.
Even if set to F, battery B → switch BS → contact Q → relay RL contact NC → movable contact COM → wiper switch W
Since power is supplied from S to wiper motor M, wiper motor M continues to operate.

When the wiper motor M comes to the normal position, the movable piece O of the automatic fixed position stop device switches to the contact P, so the circuit is made up of the wiper motor M → contact P → movable piece O → contact NC → movable contact COM → wiper switch → wiper motor M. is formed, and the wiper motor M suddenly stops.

Next, when the wiper switch WS is set to INT, one end of the wiper motor M is connected to the movable contact COM of the relay RL via the wiper switch WS, and the ground side of the astable multivibrator is also connected to the ground E via the wiper switch WS. Connected.

In this state, the astable multivibrator starts oscillating.

Now, suppose that transistor Trl is turned on, transistor Tr2 is connected to capacitor C2'! It is reverse biased by the load and remains OFF.

Capacitor C3 is charged with time constant R4C5, and capacitor C2 is discharged with time constant (R1+R2)C2.

The discharge of capacitor C2 progresses and transistor Tr2 is turned on.
When the level reaches this level, the transistor Tr2 is turned on and the transistor Tri is turned off.

This time, capacitor C2 is charged with time constant RIC2,
Capacitor C3 is discharged with time constant (R3+R4)C3.

Then, the discharge of the capacitor C3 progresses, and the transistor Tr
When l reaches a level where it can be turned on, the transistor T
r1. ON/OFF of Tr2 is reversed.

In this way, the astable multivibrator oscillates, and this oscillation causes the transistor Tr3 to become the transistor Tr l
Repeat ON and OFF in the same way.

When transistor Tr3 is turned on, relay RL is driven and switches movable contact COM to contact No.

Then, wiper motor M has battery B → switch B.
S → Contact NO → Movable contact COM → Wiper switch WS →
Electricity is applied to the wiper motor M, and the wiper motor M starts operating.

Then, when the transistor Tr1 is turned off and the transistor Tr2 is turned on, the transistor Tr3 is also turned off.
, relay RL is also not energized, so movable contact COM switches to contact NC.

Therefore, wiper motor M is battery B→switch BS→contact Q→movable piece O→contact NC→movable contact COM→
After the operating waist wiper arm (not shown) is operated once along the path from the wiper switch WS to the motor M, it is stopped by the above-mentioned fixed position stop device.

The wiper motor M is stopped for the OFF time of the transistor Trl determined by the discharge time of the capacitor C3.

Thereafter, the wiper motor M operates intermittently due to the above-mentioned oscillation.

By the way, the structure of the wiper switch attached to the bundle column of an automobile is arranged in the order of OFF, INT, and LOW.

Then, a rapid operation mode can be considered in which the INT is switched from the INT position to the OFF or LOW position and immediately returned to the INT, but this INT, OFF→INT or prisoner T→
When the wiper switch WS is switched in the LOW→INT operation mode, an arc is generated between the contacts of the relay RL of the wiper intermittent device, causing the contacts to weld.

That is, Fig. 2 A, B, and C show the voltage waveforms at point 00 in Fig. 1. When the wiper switch is switched from INT to OFF or INT to LOW, capacitor C3 changes to A and B in Fig. 2. As shown in (a), the discharge is rapidly completed along the path of capacitor C3 → resistor R3 → point ■ emitter of transistor Tr3 → base → point ■ → capacitor C3.

At this time, this discharge current causes the transistor Tr3 to become
No, and relay RL is also turned on.

On the other hand, the capacitor C2 is slowly discharged, and when the wiper switch WS is switched from OFF to INT or LOW to INT again, the transistor Tr2 is turned OFF because the capacitor C2 is not discharged.

Then, the discharge of the capacitor C2 is immediately completed, and the transistor Tr2 is immediately turned on.

As shown at b in FIG.
L is excited (shown in Figure 2 C, b), Figure 3 A, B
As shown in , the movable contact COM is momentarily attracted to the contact No. and then separates.

At this time, the movable contact COM has a negative potential and the contact NO has a positive potential, and because the relay RL responds to impulses, the movable contact COM quickly separates from the contact No. The starting current of the wiper motor also opens, causing an arc. .

Further, in the INT, LOW, and INT operation modes, the following arcs may occur.

Figure 5 A, B. C and D are operation mode and relay RL ON
, indicates the OFF state.

Figure 5A shows the INT-LOW operation mode, and when the mode is switched to LOW, the remaining charge in the capacitor C3 is transferred as described above from capacitor C3 → resistor R3 → point ■ → emitter of transistor Tr3 → base → point ■ → capacitor C3. Since the battery is discharged, relay RL is ON for 11 hours.

Figure 5B shows the LOW and INT operation modes, and since the discharge of the capacitor C3 is not completed while the wiper switch WS is LOW, the transistor Trl is switched to 0FF1, the transistor Tr2 is switched to 0NLINT, and the capacitor C3
It takes time until the discharge of the transistor Tri is completed and the transistor Tri is turned on.

During this delay time t2, the rear relay RL is turned ON for a time period t4.

Figure 5C shows the case of switching from INT and LOW to INT, and is a superimposition of Figures A and B.

According to this, when the relay RL is at 0FFL during t3, the movable contact COM momentarily switches to the contact NC side and then leaves to the contact No side, as shown in the fifth diagram.

At this time, if the wiper motor M is in the rotated fixed position stop position, there is a potential difference between the contacts COM and NC due to the self-generation of the wiper motor M, so the movable contact COM of the relay RL, the contact N, the contact NC, and the contact NC. occurs.

This invention turns on the power of the above-mentioned astable multivibrator.
An object of the present invention is to provide an intermittent wiper device which improves transient characteristics when turned off and prevents welding of contacts due to arc generation.

FIG. 6 shows an embodiment of the present invention, in which a capacitor C2 of an astable multivibrator is connected to earth E via a resistor R1.

As a result, even if the wiper switch WS is turned INT, OFF, or INT→LOW and INT is opened, the base current flows from battery B → emitter of transistor Tr2 → base capacitor C2 → resistor R2 → earth E, constantly charging capacitor C2. A circuit will be constructed to do this.

Also, due to this base current, Fig. 8A. As shown in B, the potential at point B is raised, so capacitor C3→
The discharge path of the capacitor C3, which is resistor R3 → point ■ → emitter of transistor Tr3 → base → point ■ → capacitor C3, is not formed, the rapid discharge of capacitor C3 is also eliminated, and relay RL is no longer turned on.

Then, even if the wiper switch WS is set to INT again, if the charge on the capacitor C3 is 0, the transistor Tr1 is turned ON, and if the transistor Tr2 is kept OFF, while the capacitor C3 is discharging and the capacitor C2 is charging, the transistor Tr1 is turned on. is OFF, transistor Tr2 is ON
In any case, for a moment the transistor T
The state (b in FIG. 2B) where rl is ON and transistor Tr2 is OFF disappears.

Therefore, since the transistor Tr3 does not momentarily turn ONL and excite the relay RL, it is possible to prevent arcing.

Furthermore, since the potential at the 0 point is pulled up by the base N current of the transistor Tr2 and a rapid discharge path for the capacitor C3 is not formed, the state in which the relay RL is turned ON as shown in FIG. Also, it is possible to prevent instantaneous relay RL from turning OFF even if the signal changes from LOW to INT again.

FIG. 7 shows voltage waveforms at point 2 and point 0 in the circuit of FIG. 6 according to the present invention.

According to this, the wiper switch WS changes from OFF to INT.
When the switch is made, the charge on the capacitor C3 is almost O. Since the capacitor C2 is in a fully charged state, the transistor Trl is immediately turned on and the wiper motor M can also be operated with a slight delay time.

As described in detail above, according to the present invention, it is possible to prevent arcing at the contacts of a relay, and thereby prevent welding of the relay contacts.

Further, when the switch is switched from the OFF state to the INT state, the wiper motor is immediately activated.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional example, Figs. 2 to 5 are for explaining the arc generation phenomenon in the conventional example, Fig. 2 A, B, and C are waveform diagrams, and Fig. 3 A , B is each partial diagram of the operating state of the relay contact, Figure 4 A, B, C, D
5A, B, C, and D are each waveform diagram and each partial diagram of the relay contact. 6 to 8 show an embodiment of the present invention, in which FIG. 6 is a circuit diagram, FIGS. 7A and B are waveform diagrams, and FIGS. 8A and 8 are waveform diagrams.
B is a partial circuit diagram and an equivalent circuit diagram. In the above figure, each symbol indicates the following. Tr l, Tr2, Tr3: transistor, C2,
C3: Capacitor, R1, R2, R3, R4: Resistor, M
: wiper motor, WS: wiper switch, RL: relay, COM: movable contact, NC, No: contact, O: movable piece, P, Q: contact.

Claims (1)

[Scope of utility model registration request] The other end of the wiper motor M whose one end is grounded is connected to a movable contact COM via a wiper motor switch WS, and one contact NC that this movable contact COM comes into contact with is connected to the movable piece O of the automatic position stop device, and the other contact No. between the emitter and the base of the transistor Tr3 of the drive circuit; , transistor Tr1. Tr2 and capacitor C
2°C3 and an astable multivibrator which is made up of resistors R1, R2, R3, and R4 and is grounded at the intermittent operation position INT of the wiper switch WS. A wiper intermittent device for preventing welding of relay contacts, characterized in that one end of a capacitor C2 is connected to earth E via a resistor.