JPH058960Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a heat pump type clothes dryer that uses a heat pump mechanism as a heat source.

(B) Prior Art Clothes dryers that use heat generated from a condenser of a heat pump mechanism as a heat source are known from, for example, Japanese Patent Application Laid-Open Nos. 57-131493 and 1982-145699.
And according to experiments, a heat pump clothes dryer requires an electrical input of 1100W to obtain 3500W of heat.
On the other hand, a positive temperature characteristic thermistor heater type clothes dryer requires an electrical input of 3500W, which is about three times as much, and a heat pump type clothes dryer takes less time to dry than an electric heater type clothes dryer. is 25
It can be reduced by ~45%. That is, the heat pump type clothes dryer has the advantage of high drying efficiency and short drying time. However, in the past, there was no suitable control method, and control was performed using a timer means, resulting in heat loss due to overdrying and the trouble of re-drying due to underdrying. Additionally, conventionally, an overload relay was required to protect the compressor from overload operation.

(c) Problems to be solved by the invention The heat pump type clothes dryer of the invention automatically detects the end of the clothes drying operation so that the clothes are always dried at a constant degree of dryness regardless of the amount or type of clothes. This makes it easier to use and increases safety by stopping drying operation even if the compressor becomes overloaded.

(d) Means for Solving Problems The heat pump type clothes dryer of the present invention has a heat pump mechanism that sequentially circulates refrigerant through a compressor, a condenser, a throttle device, and an evaporator, and is heated by the condenser. a first heat-sensitive element for measuring the temperature of a refrigerant between the compressor and the condenser; a second heat sensitive element for measuring the temperature of the air coming out of the drum;
A storage means for storing the measured temperature difference as a reference value when the measured temperature difference of the heat-sensitive element becomes approximately constant; and a drying operation when the measured temperature difference reaches a predetermined value or less than the reference value. a termination control means for terminating the drying operation; a determination means for determining whether the measured temperature of the first heat-sensitive element has reached a predetermined abnormal heating temperature; and a stop means for stopping the drying operation when the abnormal heating temperature is reached. It is characterized by having the following.

(E) Effect The temperature of the refrigerant discharged from the compressor of the heat pump mechanism is measured by the first temperature sensing element, while the drying air heated by the condenser exchanges heat with the clothes in the rotating drum and is then exhausted. The temperature at this time is measured by the second temperature sensing element. The temperature difference measured by the first and second temperature sensing elements becomes approximately constant after a while after the start of operation (constant rate drying period), and the value at this time becomes the reference value. Thereafter, near the end of drying, the measured temperature difference rapidly decreases (decrease rate drying period), and when the measured temperature difference reaches a predetermined value or less than the reference value, it is determined that drying has ended. to stop the drying operation. Further, the first temperature sensing element detects an abnormal rise in the temperature of the refrigerant due to insufficient heating of the drying air in the condenser, and stops the drying operation.

(F) Embodiment In FIG. 1, 1 is a heat pump mechanism that is the heat source of a clothes dryer, and includes a compressor 2, a condenser 3, a throttle device (capillary tube or expansion valve) 4, an evaporator 5, and an accumulator 6. and a refrigerant pipe 7, through which a refrigerant (for example, R-22) is sequentially circulated.

Reference numeral 8 denotes a drying air blowing duct, in which the evaporator 5 is located on the intake opening side, and the condenser 3 is located in the middle part.
A fan 9a and a motor 9 for blowing the air passing through the evaporator 5 into the condenser 3 are housed therein, and a drain hole 10 is also provided.

Reference numeral 11 denotes a main body frame of the clothes dryer, which has a clothes input port 13 on its front surface that can be opened and closed with a door body 12, and a rear opening covered with a back plate 14. 15
16 is a front support plate fixed to the edge of the clothes input port 13, and a rear partition plate 16 has both ends fixed to both left and right sides of the main body frame 11. Reference numeral 17 denotes a rotating drum for storing clothing, which is rotatable by having the center portion of the bottom surface 18 supported by the rear partition plate 16 via a pivot shaft 19, and the front opening edge being loosely supported by the front support plate 15. is held in 20 is an exhaust hole bored in the front support plate 15, and 21 is an air blower connected to this exhaust hole 20 via an exhaust duct 22, and includes an exhaust fan 23a and a motor 23 for driving the same. . A drum motor 24 rotates the rotary drum 17 with a belt 25.

The outlet opening 8a of the duct 8 of the heat pump mechanism 1 communicates with an air introduction hole 26 formed in the front support plate 15.

61 is the compressor 2 of the heat pump mechanism 1
and the refrigerant pipe 7a made of copper pipe between the condenser 3 and the condenser 3.
The first thermistor 61 is a first temperature sensing element fixed to the compressor, and this first thermistor 61 measures the temperature of the refrigerant discharged from the compressor via the refrigerant pipe 7a. 62 is the exhaust hole 2 in the exhaust duct 22
The second thermistor 62 is a second temperature sensing element that is positioned and fixed near zero, and this second thermistor 62 measures the temperature of the exhaust gas from the rotating drum 17.

The refrigerant, which is compressed by the compressor 2 and becomes a high-temperature, high-pressure gas, radiates heat in the condenser 3, and is further depressurized by the expansion device to become a low-temperature, low-pressure liquid, and then absorbs heat in the evaporator 5 and becomes a gas again. It constitutes a heat pump cycle that returns to the compressor 2 via the accumulator 6. and Juan 9a
The outside air sucked in is dehumidified by the evaporator 5, heated by the condenser 3, becomes drying air of about 50°C, enters the rotating drum 17 through the air introduction hole 26, and exchanges heat with the clothes. After that, open the exhaust hole 20
The air is exhausted to the outside of the machine via the blower 21.

Next, the control circuit will be explained based on Fig. 2.
63 is a start switch, 64 is a stop switch, 9,
22 and 23 are the motors, and 1 is a compressor.

Reference numeral 65 denotes a DC converting circuit, which converts the DC voltage rectified into rectangular wave pulses in a waveform shaping circuit 66, and applies the pulses to a microcomputer 67 for use in time counting. A clock oscillation circuit 68 generates pulses used to advance the program in the microcomputer 67. Reference numeral 69 denotes an initial reset circuit, which is activated when the start switch 63 is pressed to set the program in the microcomputer 67 to its initial state. 61 is the first thermistor, 62 is the second thermistor, each thermistor is connected in series with a resistor 70, 71, respectively, and the respective divided voltage values are sent to voltage comparison circuits 72, 73.
is being input. Further, the other input terminal of each voltage comparator circuit 72, 73 is connected to a microcomputer 67.
An output signal from a ladder circuit 74 that generates a staircase wave upon receiving an output from the ladder circuit 74 is input. This ladder circuit is connected to the output terminals of the microcomputer 67, and as signals are sequentially output from each output terminal, the output voltage of the ladder circuit 74 changes stepwise, and the voltage comparator circuit 72, 73
When conduction occurs and an input is received to the microcomputer 67, the microcomputer itself determines from which of the output terminals I, R... the signal is output, and determines the exhaust temperature at the outlet of the rotating drum. and the temperature of the refrigerant at the compressor outlet. 75 is a variable resistor built into the drying rate adjustment timer, and its slider is connected to one input terminal of a voltage comparison circuit 76, and the other input terminal of this voltage comparison circuit is connected to the ladder circuit 74. Connected. When the drying rate adjustment timer is set to a desired time, the position of the slider of the variable resistor 75 is set appropriately, and the voltage comparator 76 compares the partial pressure applied to this slider and the voltage generated from the ladder circuit 74.
When this comparator conducts and a signal is input to the microcomputer 67, the set time can be determined by determining from which output terminal I, R... the signal is output. I can do it. 77 is a second door switch for determining whether the door body 12 is closed, and 78 is a 50/60Hz changeover switch. 79 is a first relay winding, and when the start switch 63 is pressed, the microcomputer 67
The output signal from the output signal causes current to flow through the first relay winding 79 through the transistor, thereby closing the first relay contact 79' and forming a self-holding circuit. Reference numeral 80 indicates a second relay winding, and reference numeral 81 indicates a light emitting diode for displaying the drying operation. When the drying process has proceeded, the light emitting diode 81 is energized via a transistor in response to a signal output from the microcomputer 67, and is turned on. In addition to displaying that the drying process is in progress, the second relay winding 8
0 to close the second relay contact 80', and the first
The compressor 2 is energized through the door switch 82 and the like. 83 is the third relay winding, which presses the start switch 63 and also activates the second door switch 77.
When closed, the signal output from the microcomputer 67 energizes the third relay contact 8.
3' is closed and the motors 9, 22, 23 are energized.
84 is a buzzer for indicating the end of operation, and 85 is a light emitting diode for indicating cold air operation that lights up during cold air operation. 86 is a power plug.

The operation of the above configuration will be explained below.

When the start switch 63 is pressed, a DC voltage is applied to the microcomputer 67 through the DC conversion circuit 65, and the initial clear circuit 69 is activated to set the program in the microcomputer to its initial state. The program is sequentially advanced by signals from the clock oscillation circuit 68. First, an output current is passed through the first relay winding 79 to close the first relay contact 79' and maintain the power supply circuit. Next, the temperature of the refrigerant discharged from the compressor 2 and the temperature of the exhaust gas from the rotary drum outlet are measured by the first thermistor 61 and the second thermistor 62, the ladder circuit 74, and the voltage comparators 72 and 73, and the values are calculated using a microcontroller. It is stored in RAM (read/write memory) in the computer 67. At the same time, the value of the variable resistor 75 set by the drying rate adjustment knob is digitized using the voltage comparator 76 and the ladder circuit 74 and stored in the RAM in the microcomputer. When the door body 12 is closed, the first and second door switches 82 and 77 are closed, and the microcomputer 67 detects that the second door switch 77 is closed and outputs an output current to the third relay winding 83. and closes the third relay contact 83' to energize the motors 9, 22, 23 to rotate the drum 17 and both fans 9a, 23a, and at the same time output current to the second relay winding 80 to 2 relay contact 80' is closed and the compressor 2 is energized to start drying operation. Further, the microcomputer 67 counts the number of pulses of the power AC wave converted into a rectangular wave by the waveform shaping circuit 66 to count the operating time. This counting is performed by using a specific address in the RAM as a time counter, and the time counted and stored here is updated every minute.

By the way, the first and second thermistors 61 and 62
The temperature of the refrigerant and the temperature of the exhaust gas at the drum outlet, respectively measured in the drying operation, change approximately as shown in FIG. 3 during the drying operation.
That is, the difference between the two measured temperatures increases for a while after the start of the drying operation, but when it reaches a certain temperature difference a, it reaches a steady state and hardly changes (constant rate drying period). The temperature difference a at this time is taken as a reference value. After this steady state continues for a while, the difference between the two measured temperatures begins to decrease just before the end of clothes drying (decrease rate drying period), and the drying rate at this time is approximately 80%. Therefore, in Fig. 3, when the drying operation is stopped at _T2 when the difference in the two measured temperatures reaches (a-b) degrees (where b is any predetermined positive number),
Operation can be completed with a drying rate of approximately 90%.

As a result of repeated various experiments, it was found that a steady state is reached after 20 minutes have passed after the start of operation under any load, so in this example, the time T ₁ until the difference in the two measured temperatures becomes approximately constant is determined. was set to 20 minutes. Therefore, when 20 minutes have passed after the start of operation, the refrigerant temperature at the compressor outlet and the drum outlet temperature, which had been constantly updated and stored in the RAM, are taken out, the difference between them is calculated, and that value is used as the reference value a. Said
Store it in a different address in RAM. Thereafter, when the difference between the two measured temperatures reaches (a-5) degrees (in this example, b is set to 5 degrees Celsius), the drying operation is ended and the operation is shifted to the cold air operation.

Even if drying operation is still being performed 180 minutes after the start of operation, the system will shift to cold air operation. This is to protect against failure of the thermistors 61, 62, etc.

After the drying operation is completed and the cold air operation is started,
When the drum outlet temperature falls below 40° C., the third relay contact 83' is opened, the motor 24 is stopped, and the cold air operation is ended, and the first relay contact 79' is opened to release the self-holding of the power supply. Also, cold air operation is not allowed to run for more than 5 minutes.

Furthermore, due to a malfunction of the fan motor 9, air cannot be blown to the condenser 3, or the condenser 3
or clogging of the evaporator 5, the heating of the drying air in the condenser 3 may occur.
When the refrigerant temperature discharged from the compressor 2 reaches 120℃ (abnormal heating temperature), it is determined that there is an abnormality and the drying operation is stopped after entering a cool-down period to prevent overloading the compressor 2 and ensure safety. is increasing.

(g) Effects of the invention According to the invention, the temperature difference between the refrigerant temperature at the compressor outlet of the heat pump mechanism and the temperature of the exhaust air after the drying air obtained by the heat pump mechanism exchanges heat with the clothes can be used to dry clothes. By controlling the drying operation, it is possible to automatically end the drying operation at a constant degree of dryness regardless of the amount and type of clothes, and it is possible to obtain a heat pump type clothes dryer that is easy to use. In addition, the first temperature sensing element is also used to detect overload operation of the compressor, and if the refrigerant temperature rises abnormally, the drying operation is stopped, increasing the safety of the clothes dryer and reducing the number of parts used. This can reduce manufacturing costs. Furthermore, since the heat pump mechanism is the heat source, the drying air does not reach an unnecessarily high temperature of 50°C, which prevents the clothes from becoming too hot, thereby preventing them from being damaged by heat.

[Brief explanation of the drawing]

The drawings all relate to embodiments of the heat pump type clothes dryer of the present invention; FIG. 1 is a sectional side view, FIG. 2 is an electric circuit diagram, FIG. 3 is a temperature characteristic diagram, and FIG. 4 is a flow chart. 1... Heat pump mechanism, 2... Compressor, 3...
... Condenser, 17 ... Rotating drum, 61 ... First thermistor, 62 ... Second thermistor.

Claims (1)

[Scope of utility model registration request] A heat pump mechanism configured by sequentially circulating refrigerant through a compressor, a condenser, a throttle device, and an evaporator, the drying air heated by the condenser is guided to a rotating drum, and the clothes in the rotating drum are dried. a first heat-sensitive element that measures the temperature of the refrigerant between the compressor and the condenser; a second heat-sensitive element that measures the temperature of the air exiting the rotating drum; and the first and second heat-sensitive elements. 2 storage means for storing the measured temperature difference as a reference value when the measured temperature difference of the heat-sensitive element becomes approximately constant; and a storage means for storing the measured temperature difference as a reference value when the measured temperature difference reaches a predetermined value or less than the reference value. termination control means for terminating the operation; determination means for determining whether the measured temperature of the first heat-sensitive element has reached a predetermined abnormal heating temperature; and stop means for stopping the drying operation when the abnormal heating temperature has been reached. A heat pump type clothes dryer comprising: