JPH0125093Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a wiper device that wipes the windshield of an automobile with a wiper blade.

(Prior art) In this type of wiper device, when there is a lot of snow or foreign objects are caught in the wiper blades, a large load is placed on the wiper blades, and when it is drizzling, the wiper blades stick to the windshield, which causes the wiper blades to This places a large load on the blades and may cause the wiper motor to seize up.

Therefore, conventionally, a configuration is known in which a fuse is inserted in the power supply circuit to stop the power supply to the wiper motor when a large load is applied to the wiper motor. It is troublesome to switch or replace the fuse when restoring the system.

On the other hand, there are conventionally known wiper blades that change the speed of wiper blades in response to changes in rainfall (see Japanese Patent Laid-Open No. 56-28032), but they do not have a configuration that stops the power supply to the wiper motor. Therefore, if the load on the wiper blade becomes extremely large, it is not possible to prevent the wiper motor from seizing up.

(Purpose of the invention) This invention was made to eliminate the above-mentioned drawbacks of the conventional technology.It can effectively prevent burnout of the wiper motor due to overload, and eliminates the need for troublesome restoration work such as changing fuses. The purpose is to provide a wiper device for

(Structure of the invention) In order to achieve the above object, this invention receives a switch signal from an auto-stop switch that detects a predetermined stop position of the wiper blade, and detects that the cycle of this switch signal is greater than or equal to a set value. In addition to providing a timer circuit for detection, a normally closed cutoff switch that turns off in response to a detection signal from this timer circuit is connected to the power supply circuit of the wiper motor. When it becomes abnormally long, the power supply to the wiper motor is stopped.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 1, 1 is a wiper motor that reciprocates a wiper blade (not shown) that wipes the windshield, 2 is an auto-stop switch,
The auto-stop switch 2 is driven by the wiper motor 1 and makes one reciprocation between the a contact and the b contact for each reciprocating movement of the wiper blade, so that the wiper blade reaches a predetermined stopping position, for example, at the bottom of the windshield. When it reaches the position, connect between a and c.

3 is the wiper switch, which has a HI contact for reciprocating the wiper blade at high speed, an LO contact for reciprocating the wiper blade at low speed, and a contact for intermittent movement of the wiper blade.
A first switch mechanism 4 having an INT contact, an OFF contact for stopping, and a common contact C1 operates in conjunction with this first switch mechanism 4, and operates in conjunction with the above-mentioned
Contacts S1, S2, which are selected when any of the HI, LO, INT, and OFF contacts are selected, respectively.
It consists of a second switch mechanism 5 having S3, S4 and a common contact C2. The wiper motor 1 is connected to a power source 7 via an ignition switch 6, for example, the first switch mechanism 4
When the LO contact (indicated by the broken line) is selected, power is supplied from the power supply 7 to the wiper motor 1 via the power supply circuit 9, and the wiper motor 1 rotates, for example, 1.5
The wiper blade moves back and forth at a cycle of seconds.

10 is a timer circuit with four terminals T1 to T4.
, and is supplied with power from the power source 7 through the terminal T1. Terminal T3 is connected to the second switch mechanism 5.
The switch signal d from the auto-stop switch 2 is input to the terminal T3, as will be described later. The timer circuit 10 receives the switch signal d, detects when the period of the switch signal d is longer than a set time, for example, 3 seconds or more, and outputs a detection signal e from a terminal T2. A relay coil 11 is inserted between the terminal T2 and the power supply circuit 9, and a cutoff switch 12 consisting of a normally closed contact of this relay is connected to the power supply circuit 9. 11 is energized, and the cutoff switch 12 is turned off. 13 is a return switch connected in parallel to the cutoff switch 13.

As shown in FIG. 2, the timer circuit 10 includes transistors TR1, TR2 and a capacitor C.
1, a diode D1, and resistors R1 to R7.

In the above configuration, in order to start the wiper blade, the ignition switch 6 shown in FIG. 1 is turned on, and the HI contact of the first switch mechanism 4 or
When the wiper switch 3 is turned on by selecting the LO contact, the power supply circuit 9 connected from the power supply 7 to the ignition switch 6, cutoff switch 12, wiper motor 1, LO contact or HI contact, C1 contact, and ground is closed. The wiper motor 1 rotates, and the wiper blade reciprocates at a period Tw. Along with this, the auto-stop switch 2 also turns on a-c and turns on b-c repeatedly at the cycle Tw. The Tw above is approximately 1.5 seconds if the LO contact is selected when the load on the wiper blade is small.
If you select HI contact, it will take about 0.7 seconds.

Next, to stop the wiper blade,
When the wiper switch 3 is turned off, that is, when the OFF contact of the first switch mechanism 4 is selected, if the wiper blade is not at the predetermined stop position, the auto stop switch 2 is connected between b and c. From the wiper motor 1, the LO contact of the first switch mechanism 4, C2 of the second switch mechanism 5,
A circuit is formed through the C4 contact and the b and c contacts of the auto stop switch 2 to ground, and power continues to be supplied to the wiper motor 1. When the wiper blade reaches a predetermined stop position, the auto-stop switch 2 is connected between a and c, power supply to the wiper motor 1 is stopped, and the wiper blade is stopped. As a result, no matter what timing the wiper switch 3 is turned off, the wiper blade always returns to a predetermined stop position and then stops. Auto stop switch 2 like this
The operation is the same as before.

The operation of this invention is brought about by the timer circuit 10. Prior to explaining the operation of the timer circuit 10, the switch signal d input to the timer circuit 10 will be explained. When the wiper switch 3 is on, the auto stop switch 2 repeatedly connects a-c and b-c, but when the wiper blade reaches a predetermined stop position, the auto stop switch 2 connects a-c and b-c repeatedly. connected and its c
Since the voltage of the power supply 7 is directly applied to the contact, the signal of the C contact, that is, the switch signal d, is H.
become the level. When the wiper blade leaves the predetermined stopping position, contacts b and c are connected, and contact c is connected to ground, so that the switch signal d becomes L level. The operating signal of the wiper switch 3 and the switch signal d are shown in A and B of FIG. The switch signal d is input to the terminal T3 of the timer circuit 10 shown in FIG.

The timer circuit 10 starts by detecting the falling point S of the switch signal d in FIG. 3B, and keeps the terminal T2 high for a set time T _M as shown in FIG. 3C.
maintain at the level. The above T _M is larger than the reciprocating period Tw of the wiper blade at low speed, and is set to, for example, 3 seconds. The details of the operation of the above-mentioned timer circuit 10 will be explained based on FIG. 2.

In FIG. 2, when starting the wiper blade, the wiper blade is at a predetermined stop position, so the auto stop switch 2 is set to a.
-c is connected. Therefore, point _P1 is at H level, which is the same as the voltage of power supply 7, transistor TR1 is turned on, and point _P2 is at L level,
The transistor TR2 is turned off, the terminal T2 becomes H level, the relay coil 11 is no longer energized, and the cutoff switch 12 remains on. In this state, as described above, when the wiper switch 3 shown in FIG. 1 is turned on, the wiper motor 1 rotates.

When the wiper motor 1 starts rotating and the wiper blade leaves a predetermined stop position, the auto stop switch 2 shown in FIG. 2 is connected between b and c, and the switch signal d becomes L level. When b and c are connected, capacitor C1 is charged, and the potential at point _P1 gradually decreases according to a time constant determined by the capacitance of capacitor C1 and the resistance values of resistors R1, R4, and R5. Therefore, if the time during which point _P1 maintains the H level is made to match the above set time _TM , then after the set time _TM has elapsed, point _P1 becomes L level, transistor TR1 is turned off, and point _P2 goes to H level, transistor TR2 is turned on, and terminal T2 goes to L level. In other words, detection signal e is generated, relay coil 11 is energized, cutoff switch 12 is turned off, and the wiper motor 1 is turned off. Power supply is stopped.

Therefore, when the load on the wiper blade is large, it takes a set time for the wiper blade to make one reciprocation and return to its original stop position to reconnect between a and c.
If it takes more than T _M , that is, if Tw>T _M , the power supply to the wiper motor 1 is stopped. If the wiper blade returns to its original stop position within the set time T _M , the connection between a and c is established and the switch signal d in Figure 3B becomes H level again, meaning that the c contact in Figure 2 becomes H level. Since the capacitor C1 is discharged and the point _P1 becomes the H level, the terminal T2 maintains the H level as described above. As a result, at time point R in FIG. 3C, the timer circuit 10 is reset, the terminal T2 connects to the H level, the cutoff switch 12 remains on, and power supply to the wiper motor 1 continues.

As described above, when the power supply to the wiper motor 1 is stopped during coating, when the return switch 13 is manually turned on, the power supply to the wiper motor 1 is restarted. Note that the timer circuit 10 is reset when the ignition switch 6 is turned off.

FIG. 4 shows a modification of the timer circuit 10. In the figure, the timer circuit 10 is a transistor
TR3, TR4, capacitor C2, diode D
2, D3, and resistors R11 to R15.
The resistance value is set to R11<<R12. First, when starting the wiper blade, since the wiper blade is still at a predetermined stop position, the auto-stop switch 2 is connected between a and c. Therefore, the capacitor C2 is instantly charged via the resistor 11 having a small resistance value, the _P3 point becomes H level, the transistor TR3 is turned on, the _P4 point becomes L level, and the transistor TR4 is turned off, the terminal T2 becomes H level, the relay coil 11 is no longer energized, and the cutoff switch 12 remains on.
When the wiper switch 3 shown in FIG. 1 is turned on in this state, the wiper motor 1 rotates.

When the wiper motor 1 starts rotating and the wiper blade leaves the predetermined stopping position, the auto stop switch ₂ shown in FIG. It is discharged, and the potential at point _P3 gradually decreases according to a time constant determined by the capacitance of the capacitor C2 and the resistance value of the resistor R12. Therefore,
P ₃ points maintain H level for the above set time
If you match T _M , P ₃ after T _M time elapses.
The point becomes L level, transistor TR3 turns off, and point _P4 becomes H level, transistor TR3 turns off.
4 is turned on and the terminal T2 is at L level, that is,
The detection signal e is generated, the relay coil 11 is energized, the cutoff switch 12 is turned off, and the power supply to the wiper motor 1 is stopped.

Therefore, just like the example shown in Figure 2,
When the time Tw (Fig. 3) for the wiper blade to make one reciprocation and return to its original stop position exceeds the set time T _M , the power supply to the wiper motor 1 shown in Fig. 4 is stopped; When the time Tw is less than or equal to the set time T _M , power supply to the wiper motor 1 is continued.

(Effects of the invention) As explained above, according to this invention, when the cycle of the switch signal of the auto-stop switch, that is, the cycle of the reciprocating motion of the wiper blade, exceeds the set time, the power supply to the wiper motor is stopped. As a result, a large load is placed on the wiper blades due to heavy snow or foreign matter getting caught in the wiper blades.
This prevents the wiper motor from burning out due to overload when the wiper blade reaches low speed. Moreover, after the power supply to the wiper motor is stopped,
As a return means to restart the wiper motor,
As in the embodiment, it is possible to employ means for connecting a return switch in parallel to the cutoff switch, thereby facilitating the return operation.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of this invention, Fig. 2 is a circuit diagram showing details of the timer circuit of Fig. 1, Fig. 3 is a signal waveform diagram of each part of Fig. 1, and Fig. 4 is a circuit diagram showing details of the timer circuit of Fig. 1. FIG. 7 is a circuit diagram showing a modification of the timer circuit. DESCRIPTION OF SYMBOLS 1... Wiper motor, 2... Auto stop switch, 9... Power supply circuit, 10... Timer circuit, 12... Cutoff switch, 13... Return switch, d... Switch signal, e... Detection signal.

Claims (1)

[Scope of utility model registration request] A wiper motor reciprocates the wiper blade that wipes the windshield, an auto-stop switch that detects the predetermined stop position of the wiper blade, and a switch signal from this auto-stop switch is input, and the cycle of this switch signal is determined by the set time. It has a timer circuit that detects the above condition, and a normally closed cutoff switch that turns off in response to a detection signal from the timer circuit, and this cutoff switch is connected to the power supply circuit of the wiper motor. Device.