JPS6359358B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a clothes dryer equipped with an improved drying end detection mechanism.

Configuration of conventional examples and their problems In recent years, with the spread of clothes dryers, various methods have been devised to detect the end of drying, which automatically ends the operation when the degree of dryness of the clothes to be dried reaches an appropriate state. It has been. However, conventionally devised devices lacked sufficient precision or had problems in construction.

For example, one conventional method attempts to detect the end of drying only based on the exhaust temperature at the drum outlet. However, with this method, when the amount of clothes to be dried is very small, the hot air heated by the heater is directly exhausted without touching the clothes and is detected as relatively high temperature, making it very difficult to distinguish from the drying completed state. The accuracy has become poor. Furthermore, the accuracy is greatly affected by the ambient temperature.

Next, there is a method of directly detecting the resistance value of clothing by providing a pair of electrodes within the drum, but this method has the following problems in terms of accuracy and construction. First, the resistance value of clothing hardly changes in the final stages of drying, making it impossible to make detailed judgments at drying rates of 90 to 95% or higher, and some kind of correction means is required. In addition, the accuracy of dryness detection using this electrode depends on the frequency of contact between the clothes and the electrode, and the drying rate of the clothes to be dried at each detection time varies greatly, so even if a correction means is provided, the accuracy will still be low. There is a limit above. Second, there is a problem in that the resistance value of clothing is very high even when it contains moisture. That is, in order to perform high resistance detection, it is necessary to provide sufficient insulation between elements on the control circuit, and it is also necessary to apply a relatively high voltage between the electrodes. Since such insulation between elements, moisture proofing of the circuit, and safety measures are very important in this resistance detection method, it also becomes disadvantageous in terms of cost.

OBJECT OF THE INVENTION In order to solve the above-mentioned problems regarding accuracy and configuration, the present invention aims to realize accurate drying end detection safely and inexpensively.

Composition of the Invention In order to achieve the above object, the present inventor has provided a heat exchanger that dehumidifies the highly humid air that has taken moisture from clothing;
In the clothes dryer, the clothes dryer has an inflow path through which the highly humid air flows into the heat exchanger, and an outflow path through which air dehumidified by the heat exchanger flows out, the inflow path and the outflow path each having a Temperature detectors are provided, and at the time when the time rate of change of the temperature difference between the inflow route and the outflow route detected by these temperature detectors reaches a predetermined level or more after reaching the constant rate drying period. The clothes dryer has a control section that stores the temperature difference as a reference temperature difference and terminates the operation when the subsequent temperature difference becomes larger than the reference temperature difference by a predetermined value.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows the basic configuration of an embodiment of the present invention, in which 1 is a heat exchanger, 2 is an inflow path to the heat exchanger, 3 is an outflow path from the heat exchanger, 4, 5 6 is a blowing means such as a fan driven by a motor, and 7 is a drum or the like driven by the same or dedicated motor as that for the fan. Clothes storage, 8 is a heater. In addition, the black arrows in the figure indicate the flow of air that is the direct medium for drying the clothes to be dried, and the white arrows indicate the flow of air that is the direct medium for drying the clothes to be dried. This is the flow of outside air. The air heated by the heater 8 is blown into the clothes storage 7 by the blowing means 6, and removes moisture from the clothes to be dried stored in the clothes storage 7, becoming highly humid air. This highly humid air is sent to the heat exchanger 1 through the inlet path 2, where it exchanges heat with the outside air, condenses moisture, and is dehumidified. This dehumidified air returns to the heater 8 through the outflow path 3. The clothes to be dried are dried through this air cycle. Temperature detector 4 detects the temperature of inlet route 2, and temperature detector 5 detects the temperature of outlet route 3.

A feature of the present invention is that the temperature difference between the temperature of the inflow path 2 to the heat exchanger 1 and the temperature of the outflow path 3 from the heat exchanger 1 is used as a reference for detecting the end of drying. The present invention terminates the drying operation when this temperature difference, its time change, or a combination of these reaches a predetermined level, and the heater 8
This is to achieve ideal drying conditions by turning off the chisel and switching to cold air operation. In some cases, the temperature of the inflow route 2 or the outflow route 3 detected by the temperature detectors 4 and 5 may be used alone, and the above-mentioned The predetermined level of the data may be corrected.

In FIG. 1, the order of the temperature detector 4 and the blower means 6 in the inflow path 2 may be interchanged. Furthermore, although the configuration shown in FIG. 1 is for a circulation-type clothes dryer, the present invention can also be implemented in exhaust-type clothes dryers if a small-scale heat exchanger is provided exclusively for detecting the completion of drying. is considered possible.

Next, specific embodiments of the present invention will be described with reference to FIGS. 2 and 3. In FIG. 2, the arrangement of parts using the same reference numerals as in FIG. 1 is the same as in FIG. In this embodiment, the heat exchanger 1 is arranged at the rear of the apparatus, and uses a double-blade heat exchange fan that also serves as the air blowing means 6 shown in FIG. An inflow path 2 to the heat exchanger 1 is formed at the front center of the heat exchange fan (on the left side of the fan in FIG. 2), and an outflow path 3 from the heat exchanger 1 is formed from the lower end of the outer periphery of the fan. They are formed across the front and are equipped with temperature detectors 4 and 5, respectively. The clothing storage 7 is equipped with a heater 8 at the connection port (hot air inlet) with the outflow path 3 at the lower front.
The storage itself consists of a rotating drum 9. Further, 10 at the top of the device is a motor that drives the drum 9 and the heat exchanger 1, 11 at the front of the device is a door for taking in and out clothes to be dried, and 12 at the bottom of the device
is an outlet for discharging moisture condensed by the heat exchanger 1 to the outside of the machine. Note that the black arrows shown in FIG. 2 indicate the flow of circulating air, and the white arrows indicate the flow of cooling air that cools and dehumidifies the circulating air in the heat exchanger 1.

FIG. 3 shows electrical connections regarding the control circuit of this embodiment. The temperature detectors 4 and 5 in the input and output paths to the heat exchanger 1 described above are composed of, for example, thermistors, and the electric circuit shown in FIG. 3 receives the outputs of these temperature detectors 4 and 5 as input, and The control circuit section 13 that controls the operation of the motor 10 is configured as follows. That is, in the control circuit section, 14 is a microcomputer, and 15 and 16 are temperature detectors 4 and 5, respectively.
A pair of input converting sections including, for example, an A/D converter are used to input the temperature detected by the microcomputer 14 into the microcomputer 14; , and a pair of actuators for energizing and stopping the energization of the motor 10, which are comprised of a control switching element such as a triax. In such a circuit configuration, the microcomputer 14 receives the temperature in the heat exchanger inflow path 2 and the temperature in the outflow path 3, which are input from the temperature detectors 4 and 5 via the converters 15 and 16. It performs arithmetic processing and operates to stop the heater 8 and motor 10 when a predetermined condition, which will be described later, is reached.

Next, a drying completion detection method determined within the microcomputer 14 will be described. In FIG. 4a, the temperature of the inflow path 2 to the heat exchanger 1 is shown by a solid line, and the temperature of the outflow path 3 is shown by a broken line. FIG. 4b shows the difference between these two temperatures (hereinafter simply referred to as temperature difference). This temperature difference ΔT increases during the preheating period immediately after turning on the heater, becomes almost constant during the constant rate drying period when substantial drying begins and water evaporation energy and heating energy are balanced, and as drying progresses, the amount of water evaporation (endothermic During the drying period, the lapse rate (energy) decreases and then increases again. Adding this to thermodynamics, when the drying is nearing the end, the heat exchanger 1
This is because the absolute humidity of the circulating air passing through the heat exchanger 1 decreases, and the specific heat thereof decreases accordingly, so that the temperature difference caused by passing through the heat exchanger 1 increases. The drying end detection method in the present invention is performed based on this temperature difference ΔT.

First, when the drying operation is started, the temperature at the outlet of the drum 9, that is, inside the inflow path 2 (solid line a in Figure 4) rises, but when this temperature becomes almost constant over time (Fig. 4 t ₁ ) in Figure a is determined, and it is determined that the constant rate drying period has started. Therefore, after this time point _t1 , the time when the time change ΔT/ _Δt (time _differential ) of the temperature difference shown in FIG. Let the temperature difference ΔT ₁ at time t ₂ be the reference temperature difference. This temperature difference ΔT further increases as the drying progresses, but this temperature difference ΔT becomes the reference temperature difference ΔT ₁
A time point (t ₃ in FIG. 4b) is reached at which the value increases further by a predetermined value ΔT ₂ . In this embodiment, this point is determined to be the end of drying, and the microcomputer 14 operates to stop the operations of the heater 8 and motor 10, as described above.

FIG. 5 shows the relationship between the temperature difference ΔT minus the reference temperature difference ΔT ₁ (ΔT−ΔT ₁ ) and the progress of drying of the clothes to be dried.
Figure 5 shows the change in (ΔT−ΔT ₁ ) with respect to time (the solid line is at room temperature of 30°C, the broken line is at 50°C).
°C), the marks on the graph indicate when the drying rate reached the respective value. As is clear from FIG. 5, the drying rate is almost constant for the value of (ΔT−ΔT ₁ ) regardless of the room temperature and the amount of cloth. In other words, if the operation of the dryer is stopped when the increment of the temperature difference ΔT mentioned above from the reference temperature difference ΔT ₁ reaches a predetermined value of ΔT ₂ , the desired drying rate can be obtained with less variation. can.

Effects of the Invention As described above, the present invention uses the temperature difference between the inflow path and the outflow path of a heat exchanger to detect a change in the specific heat of the drum exhaust due to a decrease in absolute humidity, thereby detecting the end of the heat exchanger. Yes, by simply using two temperature detectors as sensors, it does not require high voltage compared to the conventional method of detecting the resistance value of clothing using electrodes, and does not require insulation and moisture-proofing treatment for the control circuit. do not have. Furthermore, compared to a method that detects only the temperature of the drum exhaust, it is possible to detect the completion of drying with high accuracy even when there is a very small amount of clothes to be dried, and there is almost no influence from the ambient temperature.

Furthermore, even if the overtemperature prevention system operates and adjusts the temperature, if the end of drying is detected based on only one temperature, it will be impossible to determine the end of drying.
Since this effect does not appear on the temperature difference shown in the present invention, it is possible to effectively detect the end of drying in any case.

Furthermore, if the user is allowed to set the predetermined value ΔT ₂ of the increment of the temperature difference ΔT from the reference temperature difference ΔT ₁ mentioned above, the operation can be ended at an arbitrary drying rate at the end of the drying operation. can.

As described above, the present invention realizes a very effective and powerful detection of the end of drying, and is also advantageous in terms of cost, so it is considered to be of great significance.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a longitudinal sectional view showing the structure of a specific embodiment thereof, Fig. 3 is an electrical connection diagram regarding the control circuit of the embodiment, and Fig. 4
Figures a, b, and c show the temperature changes of the inflow route and outflow route over time, and the changes in the temperature difference between these, respectively.
FIG. 5 is a graph showing the relationship between (temperature difference) - (reference temperature difference) and drying rate. 1... Heat exchanger, 2... Inflow route, 3... Outflow route, 4, 5... Temperature detector, 6... Air blowing means,
7... Clothes storage, 8... Heater, 9... Drum, 10... Motor, 11... Door, 12... Outlet, 13... Control circuit section, 14... Micro computer, 15, 16 ...conversion section, 17, 18
...actuator.

Claims (1)

[Scope of Claims] 1. A heat exchanger that dehumidifies the highly humid air that has taken moisture from clothing, an inflow path that causes the highly humid air to flow into the heat exchanger, and a heat exchanger that dehumidifies the highly humid air that has been dehumidified by the heat exchanger. In the clothes dryer, a temperature sensor is provided in each of the inflow path and the outflow path, and the inflow path and the outflow path are detected by these temperature sensors. The temperature difference at the time when the time rate of change of the temperature difference reaches a predetermined level or more after reaching the constant rate drying period is stored as a reference temperature difference, and the temperature difference thereafter is lower than the reference temperature difference by a predetermined value. A clothes dryer equipped with a control circuit that stops operation when the clothes dryer becomes too large. 2. The control circuit section determines that the constant rate drying period has been reached when the time rate of change of the temperature difference between the inflow path and the outflow path of the heat exchanger becomes equal to or less than a predetermined value after the start of operation. Clothes dryer as described in section.