JPS5926866B2 - Dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dryer that dries damp clothes, etc., and particularly relates to a dryer that automatically detects the end of drying and activates a notification device such as a buzzer immediately before it stops operating. It is.

Conventional dryers generally use a time switch to control the operating time, and a buzzer sounds a certain amount of time before the time switch turns off.

However, in a device that automatically detects the end of drying, the time required for drying varies depending on the season, that is, the outside temperature, and it is not possible to operate the notification device by time control as in the conventional method.

This invention detects the end of drying based on the relationship between the outside air temperature and the exhaust temperature, first stops only the operation of the heating device, and continues the operation of the air blower, so that the material to be dried is sufficiently cooled by the cooling operation, and the outside air temperature increases. When the difference between the temperature and the exhaust temperature becomes small, the alarm device is activated, and when the temperature difference becomes small, the dryer stops all operations, and regardless of the season, that is, changes in the outside temperature, the system always closes the dryer immediately before it stops operating. The system enables the notification device to operate.

The present invention will be explained in detail below with reference to the drawings embodying the invention. In the drawings, reference numeral 1 indicates the outer casing of the dryer.

Reference numeral 2 denotes a drum rotatably supported around a horizontal axis within the outer casing, and forms a drying chamber in which clothes are stored.

Reference numeral 3 designates an opening provided on the front surface of the outer casing 1 for taking clothes in and out of the drum 2, and 4 designates a door that covers the opening in an openable and closable manner.

A motor 5 drives the drum 2 via a belt 6.

7 is an intake port provided on the front surface of the drum 2, and 8 is an exhaust port provided on the rear surface of the drum 2.

Reference numeral 9 denotes a hot air duct which contacts the front surface of the drum 2 to allow rotation of the drum 2 and communicates with the intake lower, and has a heating device 10 at its tip on the intake side.

The heating device is, for example, a nichrome wire, a positive temperature resistance heating element (
PTCR), gas burner, etc. are used.

Reference numeral 11 denotes a fan casing that contacts the rear surface of the drum 2 to allow rotation of the drum 2 and communicates with the exhaust port 8, and has an exhaust duct 12 on the discharge side that opens to the outside of the outer casing.

Reference numeral 13 denotes an intake fan provided within the fan casing and is driven by a motor 5 via a belt.

14 is an outside air intake port for taking in outside air supplied into the drum via the heating device 10 and the hot air duct 9.

Figure 2 is an electrical circuit diagram, in which 15 is a power plug,
16 is a switch that is linked to opening and closing of the door 14.

A relay coil 17 controls the opening and closing of a self-holding contact 17a, a normally open contact 17c connected in series with the motor 5, and a normally open contact 17b connected in series with the heating device 10.

A starting switch 18 is connected in parallel with the relay contact 17a, and is closed only while the push button is pressed.

19a is a normally closed contact controlled by the relay coil 19, and is connected in series with the relay coil 17.

20a is a normally open contact controlled by the relay coil 20, and is connected in parallel with the relay contact 17c.

A buzzer 46 is a notification device for notifying the end of the stop, and is connected in parallel with the motor 5 and in series with a normally open contact 47a controlled by a relay coil 47.

48 and 49 are lamps indicating that hot air operation and cooling operation are in progress.

The automatic detection circuit for the end of drying uses both ends AB of the motor 5 as a power source, and is provided with a full-wave rectifier 22 via a voltage drop transformer 21.

23 is a smoothing capacitor connected between both terminals of the rectifier 22.

Reference numeral 24 denotes a thermistor, which is a temperature sensing element whose resistance value decreases as the outside air temperature rises, and is installed at a suitable location within the outer casing close to the outside air temperature.

A thermistor 25 is a temperature detection element whose resistance value decreases as the exhaust temperature rises, and is installed in the exhaust duct 12.

Resistor 27, thermistor 24, resistor 26, thermistor 25
are connected to the positive side of the rectifier 22 in that order.

28 is a resistor, 29 is a voltage divider, 30 is a variable resistor, and 31 is a resistor, which are connected in series to the connection point P between the thermistor 24 and the resistor 27 in that order, and set a reference voltage for the differential amplifier 33, which will be described later. form a circuit.

32 is a Zener diode, one end of which is connected to the connection point P.

33 is a differential amplifier having a function as a first comparator, its negative input terminal 33a is connected to the connection point Q between the resistor 26 and the thermistor 25 via the resistor 34, and the positive input terminal 33b is connected to the resistor 35 and the thermistor 25. A sliding contact 29a of voltage divider 29 is connected via diode 50.

A resistor 36.37 is connected to the output terminal 33c of the differential amplifier 33, and a transistor 38.5 is connected to the connection point between the two resistors.
1 base terminal is connected.

In addition, the output terminal 33c includes a resistor 39, a voltage divider 40, and a resistor 4.
1 series circuit is connected.

A Zener diode 42 is connected to a node S between the resistor 39 and the voltage divider 40.

A sliding contact 40a of the voltage divider 40 is connected to a connection point U between a diode 50 and a resistor 35 via a diode 43.

44 is a noise prevention capacitor of the reference voltage setting circuit, which is connected to the connection point U mentioned above.

The relay coil 20 has one end connected to the positive side of the rectifier 22,
The other end is connected to the collector terminal of transistor 38.

45 is a diode connected in parallel with the relay coil 20.

Relay coil 19 is connected to rectifier 22 via a normally open contact 20b controlled by relay coil 20.

Reference numeral 52 designates a differential amplifier that functions as a second comparator, and its positive input terminal 52a is connected to a connection point Q via a resistor 53, and its negative input terminal 33b is connected to a resistor 55 and a transistor 51 via a resistor 54. The connection point ■ with the collector terminal of is connected.

Note that one end of the resistor 55 is connected to the positive side of the rectifier 22, the emitter terminal of the transistor 51 is connected to the negative side of the rectifier via a variable resistor 56, and a resistor 57 is connected in parallel to the transistor 51 and the resistor 56. Ru.

Resistors 58 and 59 are connected to the output terminal 52c of the differential amplifier 52, and the base terminal of a transistor 60 and 61 is connected to the connection point between the two resistors 58 and 59.

62 is a noise prevention capacitor connected in parallel with the resistor 59.

The collector terminal of the transistor 60 is connected to the connection point V, and the collector terminal of the transistor 61 is connected to the relay coil 47.
connected to.

One end of the relay coil 47 is connected to the positive side of the rectifier 22, and a diode 63 is connected in parallel with the relay coil 47.

Now, when the start switch 18 is closed with the door 4 closed and the door switch 16 closed, the relay coil 17 is energized and the contact 17a is closed and self-held, and the contacts 17bt17c are also closed. motor 5 and heating device 10
works.

Further, a lamp 48 in parallel with the heating device 10 lights up to indicate that drying operation using hot air is in progress.

Since the lamp 49 is short-circuited by the relay contact 17b, it does not light up.

As the exhaust temperature increases as shown in FIG. 3 as the operation progresses, the resistance value of the exhaust temperature detection thermistor 25 decreases, and the potential at point Q corresponding to the difference between the outside air temperature and the exhaust temperature, that is, the differential amplifier The potential of the negative input terminal 33a of 33 drops.

When the temperature difference between the outside air temperature Ta and the exhaust temperature Tb reaches the drying end value T1, the potential of the minus input terminal 33a is equal to or higher than the potential of the plus input terminal 33b set by the reference voltage setting circuits 28 to 31. also descends.

As a result, the differential amplifier 33 outputs a signal of positive potential.

When that output is applied to the base of transistor 38, transistor 38 becomes conductive and relay coil 20 is energized.

As a result, relay contacts 20at20b are closed, relay coil 19 is also excited, and relay contact 19a is opened.

Then, the relay coil 17 is de-energized and the contact 17 a
, 17 b t17c are opened, and the circuit of the heating device 10 is interrupted.

The contact 17c that was supplying power to the motor 5 is also opened, but since the contact 20a parallel to it is already closed, the motor 5 continues to rotate and cooling operation is started.

When the relay contact 17b is opened, the lamp 49 lights up,
Displays that cooling operation is in progress.

Since the lamp 48 has a resistance value greater than the resistance value of the heating device 10, it does not light up.

On the other hand, the output of the differential amplifier 33 mentioned above is connected to the diode 43.
During the cooling operation, the input terminal 33b is maintained at a high potential state set by the resistor 39, the voltage divider 40, and the resistor 41.

Further, the output of differential amplifier 33 causes transistor 51 to conduct.

During drying operation using hot air, the potential of the negative input terminal 52b of the differential amplifier 52 is set high so as not to become equal to or lower than the potential of the point Q mentioned above. The resistor 57 is short-circuited, and the potential of the minus input terminal 52b is set to be slightly lower than the high potential set to the plus input terminal 33b of the differential amplifier 33 described above.

The cooling operation reduces the temperature difference between the outside air and the exhaust gas, and as a result, the potential at point Q increases again.

Since the potential of the minus input terminal 52b of the differential amplifier 52 is lower than the potential of the plus input terminal 33b of the differential amplifier 33, when the temperature difference between the outside air and the exhaust gas decreases and reaches T2, the potential at point Q becomes different. The potential is higher than the potential of the negative input terminal 52b of the dynamic amplifier 52.

As a result, the differential amplifier 52 outputs an electric signal with a positive potential, making the transistors 60 and 61 conductive, and the relay coil 47 is excited.

Then, the relay contact 47a is closed and the buzzer 46 sounds.

Furthermore, the conduction of the transistor 60 short-circuits the resistor 56, and the potential of the negative input terminal 52b of the differential amplifier 52 becomes zero.

When the temperature difference between the outside air and the exhaust air further decreases and reaches T3, the potential at point Q further increases and becomes higher than the potential at the positive input terminal 33b of the differential amplifier 33.
The positive potential output of 3 disappears.

As a result, the relay coil 20 is de-energized, the contact 2'Oa is opened, and the motor 5 and buzzer 46 stop operating.

By appropriately adjusting the variable resistor 56, the negative input terminal 52b of the differential amplifier 52 is connected after the transistor 51 is turned on.
By adjusting the potential set to , the time point at which the buzzer 46 sounds can be changed.

Although an AC buzzer is used as the buzzer 46 in the above embodiment, a DC buzzer may be connected to the relay coil 47.

Also, other notification devices, such as a lamp, may be used in place of the buzzer.

In the above embodiment, a thermistor is used as the temperature sensing element, but a thermocouple or the like may also be used.

As described above, in the present invention, when the difference between the outside air temperature and the exhaust temperature increases due to the drying operation and reaches the drying end value, the operation of the heating device is stopped and the blower device continues to be operated, and the cooling operation causes the air to be heated. When the dried material is sufficiently cooled and the difference between the outside air temperature and the exhaust temperature becomes small, the alarm device is activated, and when the temperature difference becomes smaller, the entire dryer operation is stopped. Therefore, even if the time required for drying varies, the notification device can always be operated immediately before the operation is stopped.

In other words, with this type of dryer that automatically detects the end of drying,
It is not possible to predict when the dryer will stop, but with this invention it is now possible to easily know when the dryer will stop.

[Brief Description of the Drawings] Fig. 1 is a vertical sectional view of a dryer embodying the present invention, Fig. 2 is a vertical sectional view of a dryer embodying the present invention;
The figure is an electric circuit diagram, and FIG. 3 is a graph showing changes in exhaust temperature. Description of attached blade, 5: Motor, 10: Heating device, 24.25
: temperature detection element (thermistor), 33: first device (differential amplifier), 46: notification device (buzzer), 52: second device (differential amplifier).

Claims (1)

[Scope of Claims] 1. In a dryer equipped with a blower device that heats and supplies outside air with a heating device to a drying chamber that accommodates objects to be dried, and exhausts air that has contributed to drying from the same chamber, the outside air temperature and the exhaust temperature are input an electrical signal based on the difference in temperature, and when the temperature difference increases and reaches a first predetermined value, outputs an electrical signal that maintains the power supply to the blower device while cutting off the power supply circuit to the heating device. and a first device that eliminates the output of the electrical signal so as to cut off the power supply circuit to the blower device when the temperature difference decreases and reaches a second predetermined value; and the outside air temperature and the exhaust gas temperature. a second device that receives an electrical signal based on the difference between the two and outputs the signal when the temperature difference reaches a third predetermined value before reaching the second predetermined value after the first device outputs the electrical signal; A dryer comprising: a notification device operated by the output of the second device. 2. The dryer according to claim 1, wherein the second device sets a reference electric signal for comparison with a third predetermined value based on the output of the first device.