JPH0125094Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intermittent wiper drive device for an automobile that intermittently drives the wiper of an automobile.

It is desired that wipers of automobiles be driven not only continuously but also intermittently. As an intermittent wiper drive device, for example, the device disclosed in Japanese Utility Model Publication No. 54-6197 is known. Such a conventional example consists of a circuit as shown in FIG.

In FIG. 1, a wiper 1 is driven by a wiper motor 2. In FIG. Auto stop switch 5
In this case, the movable contact is selectively connected to the a and b contacts. When the wiper is in the stop positionb
If wiper 1 is at the contact point other than the stop position, a
Switched to contact.

The relay 6 is switched to the a contact (normally open) when current flows through the winding 7, and to the b contact (normally closed) when no current flows. When intermittent wiper switch 3 is closed,
The voltage of the power supply 4 acts on the transistors Tr ₁ and Tr ₂ , but the current flows to the resistor R ₂₀ , the base of the transistor Tr ₁ , and the emitter, and the transistor Tr ₁ is energized and the relay 6 inserted in the collector of the transistor Tr ₁ is activated. A current flows through the winding 7, and the movable contact of the relay 6, to which the terminal of the wiper motor is connected, is switched from the b contact to the a contact, which is connected to the power source.

As a result, power is applied to the wiper motor 2, causing it to rotate, and the wiper 1 to move from its stop position. Therefore, the movable contact of the auto-stop switch 5 is switched from a normally closed contact b connected to the other end of the wiper motor 2 to a normally open contact a connected to the power source 4.

Therefore, the capacitor C ₂₀ is charged by the series circuit of the diode D ₁₀ and the resistor R ₂₁ connected to the movable contact of the auto-stop switch 5. Therefore, the base current of the transistor Tr ₂ begins to flow, and the transistor Tr ₂ becomes energized and the transistor Tr ₁ becomes non-energized. Therefore, the relay 6 is again switched to the normally closed contact b. The wiper motor 2 continues to rotate because current flows through the contact a of the auto-stop switch 5 and the contact b of the relay 6. When wiper 1 returns to the stop position, auto stop switch 5 closes contact a.
The wiper motor 2 is switched from contact b to contact b, and the wiper motor 2 is stopped at that position. From this point on, capacitor C ₂₀ becomes the base current of transistor Tr ₂ and discharges.
As the discharge progresses, the base current of the transistor Tr ₂ decreases, the transistor Tr ₂ becomes non-conductive, and the transistor Tr ₁ becomes conductive instead. Therefore, the relay 6 switches to contact a again, and the wiper 1 starts moving again.

From now on, repeat the same operation. The capacitor C ₂₀ of such a timing circuit is connected between the collector of the transistor Tr ₁ and the base of the transistor Tr ₂ , so that the capacitor C ₂₀ is charged in both directions. Therefore, a non-polar capacitor C ₂₀ must be used.

This capacitor should provide a time constant of several seconds, and requires a large capacitance of several tens of _F. However, such large capacity non-polar capacitors have the disadvantage of being extremely expensive and large. Furthermore, since the capacitors of the two transistors are connected to provide positive feedback, a reverse voltage is applied between the base and emitter of the transistor Tr ₂ , and there is a risk that the transistor Tr ₂ may be destroyed. The purpose of the present invention is to provide an intermittent wiper device for automobiles that can solve these drawbacks, use a polar capacitor as the capacitor that provides intermittent stop time, and has stable operation. be.

The structure of the intermittent wiper device for an automobile according to the present invention that achieves the above object includes an intermittent wiper switch connected to a power source, a wiper motor whose one end is connected to the power source and drives the wiper, and a wiper motor connected to the power source and which drives the wiper. an autostop switch having a normally closed contact connected to the movable contact when in the stop position and a grounded normally open contact connected to the movable contact when the wiper is driven; and the other end of the wiper motor. a relay consisting of a normally closed contact connected to the movable contact of the auto stop switch, and a normally open contact connected to the ground, the load side power supply line of the intermittent wiper switch, and the movable contact of the auto stop switch. capacitor, resistor R ₁ and diode connected between
A series circuit of resistors R ₂ , R ₃ , and _{R 4 connected} to both ends of the capacitor and determining the intermittent stop time of the wiper together with the capacitor, the emitter is connected to the power supply line, and the base is connected to the power supply line. resistance
A first transistor is connected to the connection point of R ₂ and R ₃ , the collector of which is connected by a resistor R ₆ to the ground line separated by the ground and a protective diode D ₄ , the collector of which is connected to the base The emitter is connected to the power line, the collector is connected to the ground line through a parallel circuit of a coil for driving the relay and a protective diode _D3 , and the collector is connected to the resistors _R3 and _R4 . The second transistor is connected to the connection point of the transistor by a series circuit of a positive feedback resistor _R5 and a diode _D2 , and is made conductive or non-conductive reciprocally with the transistor.

An intermittent wiper device for an automobile according to the present invention will be explained based on one embodiment.

FIG. 2 shows a circuit diagram of one embodiment of the present invention. The wiper 1 is driven back and forth by a wiper motor 2. In this circuit, current is supplied to a power supply 4 via an intermittent wiper switch 3. One terminal of a wiper motor 2 that drives the wiper 1 is connected to a power source 4, and the other end is connected to a movable contact of a relay 6. The power source 4 also has a normally closed contact a connected to the movable contact when the wiper 1 is at the stop position, and a grounded normally open contact a connected to the movable contact when the wiper 1 is driven. An auto-stop switch 5 equipped with an auto-stop switch 5 is connected thereto.
Further, the normally closed contact b of the relay 6 is connected to the movable contact of the auto stop switch 5, and the normally open contact a of the relay 6 is grounded. Furthermore, a timing circuit capacitor C ₁ is connected in series with a resistor R ₁ and a diode D _{1 between the movable contact of the auto-stop switch 5 and the power line B connected to the load-side contact of the intermittent wiper switch 3} . .
Further, a resistor R ₂ connected to the power supply line B and resistors R ₃ and R ₄ connected in series with this resistor R ₂ are connected in series to both ends of the capacitor C 1 to determine the intermittent rest time of the wiper 1 .

The emitter is connected to the power line B on the load side of the intermittent wiper switch 3, the base is connected to the connection point of resistors R ₂ and R ₃ , and the resistor R ₆ is connected to the ground line E which is grounded by the protective diode D ₄ . The collector of the first transistor Tr ₁ is connected, the emitter is connected to the power supply line B, the base is connected to the collector of the transistor Tr ₁ , and the collector is connected in parallel to the drive coil 7 of the relay 6. The diode D3 for preventing back electromotive force of the coil 7 is connected to the ground line E, and the positive feedback resistor _D3 is connected to the ground line E.
R ₅ and a second transistor Tr ₂ connected to the connection point of resistors R ₃ and R ₄ in a series circuit of a diode D ₂ . Note that the diode _D4 inserted between the ground line E and the ground is a protection diode that protects the circuit if the power source 4 is accidentally reversely connected. Further, the diode _D2 is a diode that prevents the relay coil 7 and the resistor _R5 from affecting the timer circuit when the transistor _Tr2 becomes non-conductive.

In FIG. 2, terminals indicated by J, K, L, and M are terminals connected by a wire harness.

According to the intermittent wiper drive device for an automobile of the present invention shown in FIG. 2, when the intermittent wiper switch 3 is turned on, the voltage V _c across the capacitor C ₁ is initially 0 because the capacitor C ₁ is in a discharged state. ,
Therefore, transistor Tr ₁ becomes non-conductive and transistor Tr ₂ becomes conductive. Since the transistor T ₂ is conductive, the driving coil 7 of the relay 6 inserted into the collector of the transistor Tr ₂ is energized, and the movable contact of the relay 6 is switched from the b contact to the a contact. Therefore, the wiper motor 2 connected to the power source 4 and the movable contacts of the relay 6 starts to rotate, and the wiper 1 that is interlocked with this starts to rotate from the stopped position. Therefore, the movable contact of the auto-stop switch 5 interlocked with the wiper 1 is switched from a to b contact. The movable contact of auto stop switch 5 is grounded b
By being connected to the contacts, the capacitor C ₁ ,
Resistor R ₁ and diode D ₁ are connected in series to the power supply,
Capacitor _C1 charges quickly. capacitor
The terminal voltage V _C1 of C ₁ becomes V _C1 =V _CC R ₄ +R ₅ /R ₁ +R ₄ +R ₅ , where V _CC is the voltage of the power supply 4.

However, the collector-emitter voltage V _CE of transistor Tr ₂ , the voltage drop of diodes D ₁ and D ₂ , and the resistance
It is assumed that the voltage drop of R ₃ and the V _BE of transistor Tr ₁ can be ignored. Further, it is assumed that there is a relationship of resistance R ₃ ≫ R ₅ .

The base voltage V _B of transistor Tr ₁ is the capacitor
The voltage decreases as C ₁ charges, and when V _B becomes lower than the base-emitter potential of transistor Tr ₁ , transistor Tr ₁ becomes conductive.

Therefore, the transistor Tr ₂ becomes non-conductive, the current in the coil 7 is cut off, and the movable contact of the relay 6 leaves the a contact and returns to the b contact. At this time, the wiper motor 2 continues to rotate because it is grounded through the b contact of the relay 6 and the movable contact of the auto stop switch 5, and the wiper 1 is driven and returns to the stop position. When the wiper 1 returns to the stop position, the movable contact of the auto stop switch 5 switches to the a contact, and the wiper motor 2 is short-circuited and suddenly stops. When the movable contact of the auto-stop switch 5 returns to the a contact, the charge in the capacitor C ₁ is transferred to the resistor R ₂ ,
The capacitor _C1 is discharged through _R3 and _R4 with a time constant determined by the resistors _R2 , _R3 , and _R4 , and the base potential of the transistor _Tr1 rises above the base-emitter potential _VBE and becomes non-conductive. The transistor Tr ₂ becomes conductive, energizing the relay coil 7 again, and the wiper motor 2 is driven. The period from when the wiper 1 stops until it is driven again is the wiper intermittent rest time. The same operation is repeated thereafter.

FIG. 3 shows waveforms of the main parts of the circuit according to the present invention described above. 3. 1 is the operating state of the intermittent wiper switch 3, 2 is the voltage change of the movable contact of the auto-stop switch 5, 3 is the collector current change of the transistor Tr ₁ , 4 is the collector current change of the transistor Tr ₂ , 5 is the capacitor C ₁ Voltage change across
V _C1 and 6 represent the voltage change V _B between the base and emitter of the transistor Tr ₁ , and 7 represents the voltage change V _C across the resistors R ₂ and R ₃ , respectively.

At the same time as the intermittent wiper switch 3 is turned on, the power supply voltage V _CC is applied to the circuit at _T1 , and the wiper motor 2 starts rotating. Immediately after the wiper motor 2 rotates, the movable contact of the auto-stop switch 5 leaves contact a and switches to contact b, at time _T2 .
The potential of the movable point of auto stop switch 5 is V _CC
The potential has dropped from 0 to 0. By grounding the auto-stop switch 5, the voltage V _C1 across the capacitor C ₁ rises rapidly as shown in FIG. 3. Therefore, the base potential also increases in proportion to the voltage V _C1 , and when it reaches the base-emitter potential V _BE of the transistor Tr ₁ at time T ₃ , the transistor Tr ₁ becomes conductive and the transistor Tr ₂ becomes non-conductive. At this time, as shown in the waveform 7, the voltage V _C across the resistors R ₂ + R ₃ rises rapidly due to the action of the positive feedback resistor R ₅ from the collector of the transistor Tr ₂ and the diode D ₂ , causing the conduction of the transistor Tr ₁ to decrease. This ensures its effectiveness. The wiper motor 2 starts rotating at time _T1 and continues to rotate until the wiper 1 returns to its stop position. When the wiper 1 returns to the stop position, the movable contact of the auto-stop switch 5 becomes the power supply voltage again at time T4, as shown in ₂ . Therefore, the capacitor C ₁ begins to discharge, and the voltage V _C1 of the capacitor C ₁ drops as shown in the waveform 5. As the voltage V _C1 decreases, the base voltage V _B of the transistor Tr ₁ finally cuts off the base-emitter voltage V _BE 〓 at the time T ₅ , and the transistor Tr ₁ becomes non-conductive as shown in the waveform 4. Therefore, transistor Tr ₂ becomes conductive,
The collector potential of the transistor Tr ₂ is connected to the connection point between the collector and the resistors R ₃ and R ₄ through a positive feedback resistor R ₅ and a diode D ₂ , which are connected to the series resistors R ₂ and R as shown in the waveform at 7. The voltage V _C across the transistor _{Tr 3} is rapidly lowered to ensure that the transistor Tr ₁ is rendered non-conductive. When the transistor Tr ₂ is energized, the coil 7 is energized and the movable contact of the relay 6 is a.
The wiper motor 2 rotates and the wiper 1 is driven and leaves the stop position, so at time _T6 the movable contact of the auto-stop switch 5 is switched to point b and charging of the capacitor _C1 begins.
When the charging voltage V _C1 of capacitor C ₁ increases, the base voltage also increases, cutting off the base-emitter potential V _BE 〓, transistor Tr ₁ becomes conductive, and the transistor
Tr ₂ becomes non-conductive. This process is repeated below. Therefore, according to the intermittent wiper drive device for an automobile according to the present invention shown in FIG. 2, the wiper operating time is T ₁ to T ₄ and the wiper intermittent rest time is T ₄ as shown in FIG. 3.
~ given by T ₅ .

According to the intermittent wiper drive device for automobiles according to the present invention, it was necessary to use a non-polar capacitor _C1 for determining the wiper intermittent stop time as in the conventional example shown in FIG. Polar materials can be used, which not only makes the mold smaller, but also lowers the price.

According to the present invention, as shown in FIG. 2, the collector of the transistor Tr ₂ is connected to the connection point between the positive feedback resistor R ₅ and the diode D ₂ and the resistors R ₃ and R ₄ of the timing circuit. When the transistor Tr ₁ is switched between conducting and non-conducting by charging and discharging the capacitor C ₁ of the timing circuit,
Transistor Tr ₂ is made non-conductive and conductive, and the collector potential of transistor Tr ₂ decreases or increases, and this potential is applied to positive feedback resistor R ₅ and diode D _2.
Positive feedback is given to the potential at the connection point of the resistors R ₃ and R ₄ connected to each other, thereby making the conduction and non-conduction operations of the transistor Tr ₁ even more reliable. Since positive feedback is applied to the circuit of the present invention, switching operation is reliable and operation is stable even against noise.

In addition, the voltage of the capacitor C ₁ of the timing circuit that provides the wiper intermittent rest time of the present invention is connected to the series resistor R ₂ ,
The voltage is divided by R ₃ and R ₄ to provide the base potential of transistor Tr ₁ . Therefore, the transistor Tr 1 can be made non-conductive while the discharge voltage of the capacitor C ₁ is still high, and the operation becomes more stable compared to the conventional transistor in which the transistor Tr ₁ does not become non-conductive until the capacitor voltage becomes low.

As described above, the intermittent wiper drive device for automobiles according to the present invention has stable intermittent down time and is resistant to noise.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional intermittent wiper drive device for automobiles, Fig. 2 is a circuit diagram of an intermittent wiper drive device for automobiles according to the present invention, and Fig. 3 shows waveforms of the main parts of the circuit shown in Fig. 2. It is a diagram. In the drawing, 1 is a wiper, 2 is a wiper motor, 3 is an intermittent wiper switch, 4 is a power source, 5 is an auto-stop switch, 6 is a relay, and 7 is a drive coil for the relay 6.

Claims (1)

[Scope of utility model registration request] An intermittent wiper switch 3 connected to a power source, a wiper motor 2 having one end connected to the power source and driving the wiper 1, and a normally closed contact connected to the power source and connected to a movable contact when the wiper 1 is in a stop position. and an auto-stop switch 5 having a grounded normally open contact that is connected to a movable contact when the wiper 1 is being driven, and a normally open contact that is grounded and whose movable contact is connected to the other end of the wiper motor 2. and a relay 6 with a normally closed contact connected to the movable contact of the auto-stop switch 5, and a capacitor connected between the intermittent wiper switch 3 and the movable contact of the auto-stop switch 5.
C ₁ , a series circuit with a resistor R ₁ and a diode D ₁ ;
The capacitor C ₁ connected across the capacitor C ₁
The resistance that determines the intermittent stop time of wiper 1
The series circuit of R ₂ , R ₃ , R ₄ and the emitter are connected to the load side power supply line of the intermittent wiper switch 3,
The base is connected to the connection point with the resistors R ₂ and R ₃ ,
The collector is connected to the ground by a resistor R ₅ to the ground line separated by a protective diode D ₄
The collector of the transistor Tr ₁ is directly connected to the base, _the emitter is connected to the intermittent wiper switch 3, and the collector is connected to the ground line between the coil 7 that drives the relay 6 and the protective diode D ₃ . In addition to being connected in a parallel circuit, the collector is connected to the connection point between the resistors R ₃ and R ₄ through a series circuit of a positive feedback resistor R ₅ and a diode D ₂ , and is reciprocally conductive or conductive with the transistor Tr ₁ . An intermittent wiper drive device for an automobile, comprising a second transistor _Tr2 that becomes non-conductive.