JPH029838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a clothes dryer having a heater made of a positive resistance temperature characteristic element.

(b) Prior art The technology of using a positive resistance temperature characteristic element as a heater in a clothes dryer is disclosed in, for example, Japanese Utility Model Publication No. 57-29519;
It is known from Japanese Patent Publication No. 58-31960. The former method stabilizes the characteristics of the heater as a whole by appropriately combining multiple positive resistance temperature characteristic elements, while the latter method detects the clogging state of these positive resistance temperature characteristic elements. has been done.

By the way, this type of positive resistance temperature characteristic element has a characteristic that the amount of heat generated, that is, the power consumption changes depending on the ambient temperature. In particular, when the ambient temperature is low, the current flowing through the positive resistance temperature characteristic element increases and the power consumption decreases. It's going to get bigger.

Normally, in clothes dryers, the power of the positive resistance temperature characteristic element is determined so as to obtain the maximum drying capacity in the summer, but in this case, the power consumption by the positive resistance temperature characteristic element is undesirable when used in the winter when the temperature is low. This may cause the fuse to melt,
There is a risk that the breaker may be shut off. In addition, if a positive resistance temperature characteristic element with low power consumption is used based on winter use, the necessary heat generation will not be obtained during summer use, resulting in longer drying times and drying loads that are not yet dry. There is a drawback that the drying operation ends.

Japanese Unexamined Patent Publication No. 54-5263 discloses that by reducing the value of the rush current to the positive resistance temperature characteristic element during power-on time, that is, at the time of starting,
Publication No. 32557 discloses a clothes dryer that attempts to prevent fuse blowing and breaker shutoff by shortening the time during which inrush current flows when the power is turned on. However, with such a configuration, even if it is possible to prevent the fuse from blowing and the breaker from shutting off when the power is turned on, good operation cannot be expected against seasonal fluctuations in ambient temperature as described above. Therefore, when a large capacity positive resistance temperature characteristic element is used, power consumption increases during use at low temperatures, which may cause the breaker to shut off.

(c) Purpose of the Invention The present invention uses a positive resistance temperature characteristic element that can obtain a large heat generation capacity to obtain high drying ability, does not cause an increase in power consumption even at low temperatures, and is capable of reducing the number of fuses. To provide a clothes dryer that does not cause melting or shutting off of a breaker.

(d) Structure of the Invention The clothes dryer of the present invention includes a casing having a clothes entrance on the front surface, and a drying drum rotatably supported within the casing with an opening facing the entrance and a rotation axis in a horizontal direction. , a heater made of a positive resistance temperature characteristic element, a blower fan that blows hot air heated by the heater into the drum, a motor that rotationally drives the drying drum and the blower fan, and a current flowing through the heater that is detected. It is characterized by comprising a detection means, and a power suppression means for suppressing an increase in power consumption of the heater when the detection result of the detection means exceeds a predetermined value, and the power consumption increases even at low temperatures. will not occur.

(E) Embodiment To explain based on FIGS. 1 to 4, 1 is a casing of a clothes dryer, which is composed of a machine frame 2 with a rear opening and a rear cover 3 that closes the rear opening. A clothing entrance/exit 4 is formed in the front of the machine frame 2. Reference numeral 5 denotes a door that freely opens and closes the entrance/exit 4; 6 indicates a metal annular drum support plate fixed to the back side of the front side of the machine frame 2; and 7 indicates the rear upper and lower surfaces of the machine frame 2. A metal partition plate is installed between the drum support plate 6 and the rear part, and the drum support plate 6 and partition plate 7 are made of thick sheet metal so that they will not deform even when a load is applied.

Reference numeral 8 denotes a drying drum which is rotatably supported in the housing 1 with its front opening facing the clothing entrance 4 and with its rotating shaft in the horizontal direction. The drum body 11 is made of synthetic resin and has a cylindrical shape with a bottom and has radial slit holes 10 formed around the drum body 9, and a metal drum frame 12 is fixed to the opening edge of the drum body 11. Then, the opening peripheral surface of this drum frame 12 is covered with felt 1.
3 to the drum support plate 6, and the support shaft 9 of the drum body 11 is rotatably attached to the shaft hole of the partition plate 7 by means of a metal bearing 14 and a washer 15. Further, 16 is a lint filter, and 17 is a filter cover.

A circulation duct 18 is interposed between the drum 8 and the partition plate 7, and has an opening facing the slit hole 10, and a sealing felt 19 is interposed between the edge of the opening and the drum 8. It's inserted.

20 is a Finch-Hube heat exchanger connected to this circulation duct 18, 21 is a heating duct connected to this heat exchanger 20, and the heating duct 21 is connected to an air hole 22 formed in the drum support plate 6. A heater 2 consisting of a positive resistance temperature characteristic element (PTC heater) is installed in the vicinity of the air hole 22 in this duct 21.
It has 3. This positive resistance temperature characteristic element is
If the ambient temperature is lowered in order to maintain the heat generating capacity, the power consumption will increase in proportion to it, and therefore the current flowing through the element will also increase.

Reference numeral 24 designates an outside air duct that leads outside air to the heat exchanger 20 from an outside air intake 25 opened on the upper surface of the machine frame 2, and 26 represents an exhaust port opened on the lower surface of the machine frame 2.

27 is an outside air intake fan, and 28 is a circulation fan, which are coaxially attached to a common drive shaft 29.

A motor 30 rotates the drum 8 with a drum drive belt 31, and rotates the outside air intake fan 27 and the circulation fan 28 with a fan belt 32 through the drive shaft 29, respectively.

The circulating hot air heated by the heater 23 removes moisture from the load such as clothes in the drum 8, and this moist circulating hot air passes through the circulation duct 18 and exchanges heat with outside air in the heat exchanger 20. The moisture created at this time is discharged to the drain port 3 via the drain pipe 33.
4 to the outside, and this cooled circulating air returns to the heater 23 in the heating duct 21. On the other hand, the outside air taken in from the outside air intake port 25 undergoes heat exchange with the heat exchanger 20 and becomes warm air, which is then turned into the exhaust port 25.
Exhaust from.

Next, the circuit configuration will be explained based on FIG. 5. 35 is a power switch, 36 is a first door switch that cuts off electricity to the motor 30 and heater 23, 37 is a DC converter circuit, and 38 is a commercial frequency AC voltage. 39 is a microcomputer element (hereinafter referred to as a microcomputer) that programs a flowchart to be described later and controls the overall operation according to this program; 40 is a microcomputer element in this microcomputer 39; a clock oscillation circuit for running the program, 4
Reference numeral 1 designates an initial reset circuit, and when the power switch 35 is pressed, this initial reset circuit 41 is activated and the program in the microcomputer 39 is set to its initial state. A variable resistor 42 rectifies and smoothes the secondary output of the transformer 55 connected in series with the heater 23, and inputs its partial voltage value to the voltage comparator circuit 43. The variable resistor 42, transformer 55, etc. constitute a detection means for detecting the current flowing through the heater 23. In this embodiment, the variable resistor 42 is set so that a voltage of 3V is input to the voltage comparator circuit 43 when the current flowing through the heater 23 is 12A.
are being adjusted. Further, the output signal of the D/A conversion circuit 44 which receives the output from the microcomputer 39 and generates a staircase wave is input to the other input terminal of the voltage comparison circuit 43. This D/A conversion circuit 44 is connected to output terminals A, A, C, and E of the microcomputer 39, and as signals are sequentially output from each output terminal A, B, C, and E, the D/A conversion circuit 44 When the output voltage changes in a stepwise manner, the voltage comparison circuit 43 becomes conductive, and an input is received to the microcomputer 39, when a signal is output from any of the output terminals A, B, C, and E. The microcomputer 39 itself determines whether the 45 is a start switch.

When the power switch 35 is pressed and the start switch 45 is pressed, operation starts, and the microcomputer 39
Output signal from output terminal O of transistor 4
6, turn on the triax 47 and turn on the heater 2.
3 is energized, an output signal is also output from the output terminal of the microcomputer 39, and current is passed through the relay winding 49 through the transistor 48, closing the relay contact 49a and energizing the motor 30. 50 is a second door switch for the microcomputer 39 to determine whether the door 5 is closed or not, and 51 is a 50/60Hz changeover switch. Furthermore, 52 is a drying time setting circuit, which sets the time for which electricity is supplied to the heater 23, and performs drying operation for that time.

In the above circuit configuration, when the output voltage of the D/A conversion circuit 44 becomes 3V, the voltage comparison circuit 43 becomes conductive and if there is an input to the input terminal K of the microcomputer 39, the current flowing to the heater 23 becomes 12A. -ing

Here, how to perform the control aimed at by the present invention will be explained based on a flowchart.

When the program starts, the microcomputer 39 sets the optimum drying time as the operating time T and also sets 2 seconds as the ON time. That is,
In this embodiment, the power consumption of the heater 23 is controlled in units of 2 seconds as described later. and this
The ON time indicates how long the heater 23 is energized within one unit of 2 seconds. Here, the initial value of ON time is 2.
It is set so that it is always energized for one second, that is, one unit of time. Subsequently, the microcomputer 39 sets the output states of output terminals A, I, U, and E to a state such that 0V is output from the D/A conversion circuit 44.

If the start switch 45 is pressed and the door 5 is closed, the operation will start, and the heater 2 will open as described above.
3. When the motor 30 is energized, a voltage corresponding to the current flowing through the heater 23 is taken out from the transformer 55 and inputted to the voltage comparison circuit 43. On the other hand, the microcomputer 39 repeatedly changes the output voltage of the D/A conversion circuit 44 in units of 2 seconds. That is, initially the D/A conversion circuit 44
Since 0V is output from , voltage comparator circuit 4
The signal output from 3 does not change. At this time, the microcomputer 39 changes the output signals of the output terminals A, B, C, and E so as to raise the output of the D/A conversion circuit 44 by one level. In this way, the microcomputer 39 increases the output voltage level of the D/A conversion circuit 44 by changing the output signals from the output terminals A, B, C, and E. This operation continues until a signal is input from the voltage comparator circuit 43 to the input terminal K within a unit of 2 seconds.

When the level of each input terminal of the voltage comparison circuit 43 is reversed due to the rise in the output voltage level of the D/A conversion circuit 44, the output signal of the voltage comparison circuit 43 is inverted, and this signal is input to the microcomputer 39. When this inverted signal from the voltage comparator circuit 43 is input to the microcomputer 39, the microcomputer 39 temporarily stops increasing the output voltage level of the D/A converter circuit 44, that is, outputs from output terminals A, B, U, and E are input to the microcomputer 39. The signal change is stopped, and the output of the D/A conversion circuit 44 is held as it is until 2 seconds, which is one unit at that time, has elapsed.

Subsequently, when 2 seconds, which is one unit at that time, has elapsed, the microcomputer 39 calculates the output voltage of the D/A conversion circuit 44 from the output states of output terminals A, B, C, and E, and sets the output voltage to the reference value. Compare with 3V. If the output voltage is higher than 3V, this indicates that the current flowing through the heater 23 is becoming larger than 12A, so the currently set ON time is shortened by 0.1 seconds. Due to this, in the next unit of 2 seconds,
The energization time to the heater 23 is shortened by 0.1 seconds,
An increase in power consumption in the heater 23 will be suppressed. Conversely, if the output voltage is lower than 3V, then the current flowing through the heater 23 is
This shows that it is becoming smaller than 12A, so
Increase the currently set ON time by 0.1 seconds (maximum ON time is 2 seconds). Due to this,
In the next unit of 2 seconds, the power supply time to the heater 23 is increased by 0.1 seconds, and the reduction in power consumption in the heater 23 is suppressed. Also, if the output voltage is around 3V, this indicates that the current flowing through the heater 23 is around 12A, so the drying operation will continue without changing the currently set ON time. Continue.

As mentioned above, in this embodiment, the microcomputer 3
D/A when input signal is applied to input terminal key of 9
The current flowing to the heater 23 is detected from the output voltage of the conversion circuit 44, and when the detection result exceeds a predetermined value, the time for energizing the heater 23 is shortened.
Power consumption is reduced through ON/OFF control.

In this embodiment, the heater 23 is turned on and off every 2 seconds.
Although OFF control is performed, it can be said that it is appropriate to perform it in a cycle of 1 to 3 seconds. this is
If the ON/OFF cycle becomes shorter, the heater 23 is turned ON/OFF frequently, causing problems such as when other loads in the room, such as light bulbs, flicker. Moreover, if the length is too long, the breaker may be tripped by the rush current when the heater 23 is turned on.

As described above, the power consumption of the heater 23 is determined when the current detection result exceeds a predetermined value.
This increase can be suppressed by means of reducing power consumption by shortening the energization time. Therefore, even if the power of the positive resistance temperature variable element is determined to provide maximum drying capacity in the summer, the power consumption of the positive resistance temperature variable element may undesirably increase when used in the winter when the temperature is low. There is no risk of blowing the fuse or tripping the breaker. Furthermore, since it is not necessary to use a positive resistance temperature characteristic element with low power consumption based on winter use, sufficient heat generation and drying ability can be obtained even during summer use.

(F) Effects of the Invention According to the present invention, even if a positive resistance temperature characteristic element whose calorific value automatically changes depending on the ambient temperature is used as a heater, the current flowing through the heater cannot be detected. to suppress the increase in power consumption. Therefore, it is possible to use a positive resistance temperature characteristic element with a large heat generating capacity that uses the maximum current that the commercial power supply can tolerate at normal temperatures (e.g. 20°C), and has a high drying capacity such as shortening drying time. obtained, and
It is possible to provide a clothes dryer that does not increase power consumption even at low temperatures (for example, 0° C.) and does not cause fuses to blow out or breakers to shut off.

[Brief explanation of drawings]

The drawings all relate to an embodiment of the clothes dryer of the present invention, and FIG. 1 is a front view, FIG. 2 is a rear view with the rear cover removed, and FIG. 3 is a main part view taken along the line A-A' in FIG. 1. , Figure 4 is a main part view of the BB' cross section of Figure 1,
FIG. 5 is an electric circuit diagram, and FIG. 6 is a flowchart. 5... Clothes entrance/exit, 1... Housing, 8... Drying drum, 32... Heater, 2... Circulating fan,
30...Motor, 47...Triack, 44...
...D/A conversion circuit.

Claims (1)

[Claims] 1 A casing having a clothing entrance/exit on the front surface, a drying drum rotatably supported within the casing with an opening facing the entrance and with its rotational axis oriented horizontally, a heater comprising a positive resistance temperature characteristic element, and the heating device. a blower fan that blows hot air heated from a dryer into the drum, a motor that rotationally drives the drying drum and the blower fan, a detection means that detects the current flowing through the heater, and a detection result of the detection means that indicates a predetermined value. A clothes dryer comprising a power suppressing means for suppressing an increase in power consumption of the heater when the power consumption exceeds the power consumption of the heater.