JP3064604B2 - Clothes dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clothes dryer for drying household clothes.

[0002]

2. Description of the Related Art In recent years, household clothes dryers are provided with a filter for removing lint and the like in a drum for drying clothes.
If the filter has too much lint and is clogged,
A clothes dryer that reports clogging by an indicator light has been proposed.

Conventionally, this type of clothes dryer has been disclosed in
No. 16631. That is, a current change of a positive characteristic temperature-sensitive resistance heater (hereinafter, referred to as a PTC heater) is detected by a current transformer, and if the detected PTC heater current is smaller than a set value, clogging is notified.

[0004]

In such a conventional clothes dryer, the PTC heater current varies depending on the intake air temperature, air volume, and voltage. Since the current change of the heater is much larger than the current change due to clogging, it is almost impossible to find a set value that can detect clogging only by the current change in consideration of all fluctuations. There is a problem that it is impossible to detect a clogged state.

[0005] The present invention solves the above-mentioned conventional problems.
It is an object of the present invention to provide a clothes dryer capable of detecting clogging without being affected by a temperature change or a voltage change.

[0006]

To achieve the above object, the present invention provides a heating means comprising a PTC heater, a means for blowing air to the heating means, a filter provided in a blowing path of the blowing means, Temperature detection means for detecting the intake air temperature of the heating means, voltage detection means for detecting the voltage of the heating means, current detection means for detecting the current of the heating means, and the heating means and the blowing means by the temperature detection means Control means for controlling the power of the heating means from the voltage detection means and the current detection means, the filter of the filter from the temperature detected by the temperature detection means and the calculated power The problem solving means is to detect clogging.

[0007]

According to the present invention, a PTC is provided by the means for solving the above problems.
The power is obtained from the voltage and current of the heater, the clogging of the filter is detected from the intake air temperature and the power of the PTC heater, and the clogging can be accurately detected regardless of the voltage change or the temperature change.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a rotating drum 1 contains a material to be dried, and is heated by a PTC heater (heating means) 2 to circulate hot air sent from a blower fan (blower means) 3 to circulate the material to be dried. dry. The motor 4 rotates the rotary drum 1 and the blower fan 3. Blower fan 3
Is called a heat exchange fan or a two-wing fan,
It has a function of circulating the air in the rotating drum 1 and cooling and dehumidifying. The filter 5 is provided in a blowing path of the blowing fan 3, that is, an air outlet of the air in the rotating drum 1. The temperature detecting means 6 detects the temperature of the intake air of the PTC heater 2. When the filter 5 is clogged with lint or the like, the amount of air to be blown is reduced, the heating power of the PTC heater 2 is reduced, the drying time is lengthened, and the drying efficiency is reduced.

The voltage detecting means 7 detects a voltage between lines of the AC power supply 8. The current detecting means 9 includes a current transformer 9a and a current-voltage conversion circuit 9b, and detects an input current. The control device 10 controls the PTC heater 2 and the motor 4 in accordance with signals from the temperature detecting means 6, the voltage detecting means 8, and the current detecting means 9, and comprises a microcomputer for performing calculations and determinations and a peripheral circuit thereof. Means 11 and power control means 12. The power control means 12 is a relay or power semiconductor 12a, 1
2b and 12b, and drives and controls the heaters 2a and 2b and the motor 4 constituting the PTC heater 2. That is, the PTC heater 2 is
Can be controlled in at least two levels, strong and weak. Here, if the rotation of the blower fan 3 is controlled, not only can the heating output be controlled continuously, but also the blower conditions when clogging is detected can be set to a constant value. The operation display circuit 13 includes a key switch, a clogging indicator, and the like included in the operation panel.

The operation of the above configuration will be described with reference to FIGS. 3 and 4. FIG. 3 is a characteristic diagram of the input power P of the PTC heater 2 and the intake air temperature T for illustrating the method of detecting clogging according to the present invention. The input power P of the PTC heater 2 is represented by the product of the temperature difference ΔT between the Curie temperature Tq and the intake air temperature T and the radiation coefficient H, and P = H (Tq−T). When the filter 5 is clogged, the heat radiation coefficient H decreases due to a decrease in the air volume due to the clogging. Therefore, since the Curie temperature Tq is constant, the heat radiation coefficient H can be obtained from the input power P and the intake air temperature T. Can be estimated. A in FIG. 3 indicates PTC when there is little clothing.
The relationship between the input power P of the heater 2 and the intake air temperature T is shown, where A 'shows the characteristics when there is a lot of clothes, and B shows the characteristics when the filter is clogged. C indicates a clogging detection level of the input power P of the PTC heater 2 with respect to the intake air temperature T for determining clogging. The detection level Ps can be set substantially linearly according to the intake air temperature T as Ps = K-kT. Here, K and k are constants.

FIG. 4 is a flowchart of one embodiment of the present invention described above, which shows a subroutine for detecting clogging. In step 101, the intake air temperature of the PTC heater 2 is detected. It is determined whether the input power is weak. In order to make the flow of clogging detection as simple as possible, it is necessary to make the air condition and the power condition of the PTC heater 2 constant, and set the PTC heater 2 to a weak condition in consideration of the AC power supply capacity to reduce clogging. judge. Note that a method of performing feedback control of the rotation speed of the blower fan 3 and setting the input power of the PTC heater 2 to a relatively low level is excellent. In step 103, the voltage and current of the PTC heater 2 are detected, and in step 104, the power of the PTC heater 2 is obtained from the product of the voltage and current. In the embodiment shown in FIG. 2, since the input of the motor 4 is also included, it is necessary to subtract the motor input. In step 105, it is checked whether the input current or the input power change has become substantially constant. At this time, a method of examining a change within a certain time or a PTC heater 2
May be set to be weak and a method of providing a delay of a fixed time may be used. Next, clogging is determined in step 106. A detection table corresponding to the intake air temperature T of the PTC heater 2 is compared with the input power P, or a detection level Ps =
K-kT is compared with the input power P, and if P <Ps, or a decrease in the radiation coefficient H is determined from the intake air temperature T of the PTC heater 2 and the input power P of the PTC heater 2, clogging is detected. If clogging is determined in the determination routine of step 106, a clogging flag is set in step 107, and the operation display circuit 1 is set in step 108 by the clogging flag.
Turn on the clogging indicator light.

As is apparent from the above description, according to the present embodiment, the power of the PTC heater 2 is obtained from the voltage detecting means 7 and the current detecting means 9 and the intake air temperature detected by the temperature detecting means 6 and the PTC heater 2 are determined. The clogging of the filter 5 can be accurately detected from the power.

In the above embodiment, the dehumidification-type clothes dryer has been described. However, it is apparent that the same effect can be obtained with an exhaust-type clothes dryer. Further, the voltage detecting means 7
By correcting the decrease in the power of the PTC heater 2 caused by the decrease in the air flow, the accuracy can be further improved. In addition, if the number of rotations of the blower fan 3 is controlled to be constant at the time of detection of clogging, voltage correction becomes unnecessary, and it goes without saying that detection accuracy is improved.

[0015]

As apparent from the above embodiments, according to the present invention, a heating means comprising a PTC heater, a means for blowing air to the heating means, a filter provided in a blowing path of the blowing means, Temperature detection means for detecting the intake air temperature of the heating means, voltage detection means for detecting the voltage of the heating means, current detection means for detecting the current of the heating means,
Control means for controlling the heating means and the blowing means by the temperature detection means, wherein the control means calculates the power of the heating means from the voltage detection means and the current detection means and detects the power by the temperature detection means Since the clogging of the filter is detected from the calculated temperature and the calculated power, the power of the heating means is obtained from the voltage detecting means and the current detecting means, and the intake temperature detected by the temperature detecting means and the calculated power are obtained. In addition, clogging of the filter can be detected without being affected by a temperature change or a voltage change, and the detection can be accurately performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a clothes dryer according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the clothes dryer.

FIG. 3 is a characteristic diagram of heater input and intake air temperature for explaining clogging detection of the clothes dryer.

FIG. 4 is a flowchart illustrating the operation of the clothes dryer.

[Explanation of symbols]

 2 PTC heater (heating means) 3 Blow fan (blowing means) 5 Filter 6 Temperature detecting means 7 Voltage detecting means 9 Current detecting means 11 Control means

Continuing from the front page (72) Inventor Masamitsu Mihara 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-268599 (JP, A) JP-A-53-11350 (JP) JP-A-58-7296 (JP, A) JP-A-4-256799 (JP, A) JP-A-4-200593 (JP, A) JP-A-63-315100 (JP, A) 54-145194 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) D06F 58/28

Claims (2)

(57) [Claims] 1. A heating means comprising a positive-characteristic temperature-sensitive resistance heater, a blowing means for the heating means, a filter provided in a blowing path of the blowing means, and a temperature detecting means for detecting an intake air temperature of the heating means. A voltage detection unit for detecting a voltage of the heating unit, a current detection unit for detecting a current of the heating unit, and a control unit for controlling the heating unit and the blowing unit by the temperature detection unit. Means for calculating the power of the heating means from the voltage detection means and the current detection means, and detecting clogging of the filter from the temperature detected by the temperature detection means and the calculated power. . 2. The control means controls the input power of the heating means in at least two levels, high and low, and compares the temperature detected by the temperature detection means with the calculated power when the input power is low, and provides a filter. The clothes dryer according to claim 1, wherein clogging of the clothes is detected.