Control method of washing and drying all-in-one machine and washing and drying all-in-one machine

Abstract

The invention provides a washing and drying all-in-one machine control method which comprises a drying program and comprises the following steps that before the drying program is executed, the external environment temperature is obtained; and if the external environment temperature is smaller than the first preset temperature, a compressor of the heat pump system is started, and a condenser is preheated. A preheating program is added, when the external environment temperature is too low, the condenser is preheated before a drying program is started, the problems of slow temperature rise and low drying efficiency caused by the influence of the external temperature during the drying program can be avoided, in addition, an auxiliary heating device does not need to be additionally added while the preheating function is achieved, and the energy consumption is reduced. Not only is space saved, but also current over-limit of the whole machine is avoided, and energy consumption is reduced. The invention further provides the washing and drying all-in-one machine used for executing the control method of the washing and drying all-in-one machine.

Description

Technical Field

[0001] The present invention belongs to the field of household appliances, and in particular relates to a control method for a washer-dryer, and also relates to a washer-dryer applying the control method for the washer-dryer. Background Art

[0002] With the improvement of living standards, people have higher and higher requirements for the quality of life, and thus higher and higher requirements for product quality, performance, humanization of use, intelligent operation and other aspects. As an excellent product, the washer-dryer has gradually entered people's lives. The washer-dryer is a device that combines washing and drying, which greatly increases the convenience of user use. The heat pump system of the washer-dryer uses a compressor to convert the refrigerant into cold and hot energy in the heat exchanger. The heat energy is used in conjunction with the fan to heat the air temperature in the barrel, so that the moisture in the clothes evaporates, and the water vapor enters the cold energy area through the air duct for condensation, thereby realizing the drying function. However, at low ambient temperatures, the heating rate of the heat pump system will become very slow due to the influence of temperature, which will in turn affect the efficiency of the drying program, extend the drying time, and increase consumption.

[0003] The Chinese invention patent with application number CN201910364241.7 discloses a drying device, a clothes dryer, a washer-dryer and a drying method, wherein the drying device includes a first heating device, a heat pump system, a container for placing objects to be dried, a fan for realizing gas circulation between the container and the heat pump system, and a first heating device arranged in the channel of the gas circulation; the heat pump system includes a compressor and a condenser; the drying device also includes a controller and a cooling device for cooling the compressor; the controller is used to obtain a drying instruction, control the fan, the first heating device and the heat pump system to start working; determine that the compressor outlet temperature is greater than or equal to the first temperature threshold, or the condenser outlet temperature is greater than or equal to the second temperature threshold, and control the first heating device to stop working; determine that the compressor outlet temperature is greater than or equal to the fifth temperature threshold, and control the cooling device to start working; the fifth temperature threshold is less than the first temperature threshold or the second temperature threshold. A drying device in the embodiment of the patent increases the temperature in the drying stage through the auxiliary heating device, speeds up the drying efficiency, and thus greatly reduces the time consumption of the drying procedure.

[0004] However, the heating tube heating in the above scheme will increase the energy consumption of the whole machine, increase the instantaneous power, increase the load of the power supply circuit of the whole machine, and may reduce the energy efficiency level.

[0005] Therefore, designing a control method for a washer-dryer that can improve drying efficiency and can be used normally in a low-temperature environment without adding an additional auxiliary heating system and without increasing the load on the power cord of the entire machine has become a technical problem that needs to be urgently solved by technical personnel in this field.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a control method for a washer-dryer. The present invention adds a preheating program. When the external ambient temperature is too low, the condenser is preheated before entering the drying program. This can avoid the problem of slow heating and reduced drying efficiency caused by the influence of the external temperature during the drying program. In addition, while realizing the preheating function, the present invention does not require an additional auxiliary heating device, which saves space and avoids over-limit of the whole machine current, reduces energy consumption, and overcomes the problem in the prior art that the use of heating tubes for heating leads to increased energy consumption of the whole machine, increased instantaneous power, increased load on the power supply circuit of the whole machine, and reduced energy efficiency level.

[0008] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0009] A control method for a washer-dryer includes a drying program, and the control method includes the following steps:

[0010] Before the drying process is executed, obtain the external environment temperature;

[0011] If the external environment temperature is lower than the first preset temperature, the compressor of the heat pump system is started to preheat the condenser.

[0012] Furthermore, it also includes:

[0013] Before the drying process is executed, obtain the temperature at the compressor exhaust pipe;

[0014] If the temperature at the compressor exhaust pipe is lower than the second preset temperature, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed.

[0015] Furthermore, before the drying program is executed, if the external environment temperature is greater than or equal to the first preset temperature, and / or the temperature at the compressor exhaust pipe is greater than or equal to the second preset temperature, the compressor is not started before the drying program is executed.

[0016] Furthermore, a washing procedure is included, and when the dehydration speed in the dehydration stage of the washing procedure reaches the maximum speed, the external environment temperature and the temperature at the exhaust pipe of the compressor are obtained;

[0017] If the external environment temperature is lower than the first preset temperature and the temperature at the compressor exhaust pipe is lower than the second preset temperature, the compressor of the heat pump system is started to preheat the condenser before the drying program is executed.

[0018] Further, when the spin speed in the spin stage of the washing program reaches the maximum speed, the motor power is obtained;

[0019] If the motor power is less than the preset power, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed;

[0020] If the motor power is greater than the preset power, the compressor will not start before the drying process is executed.

[0021] Furthermore, when the condenser is preheated, the rotation speed of the compressor is lower than the rotation speed of the compressor after entering the drying program.

[0022] Furthermore, during the process of preheating the condenser, the rotation speed of the compressor is proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature.

[0023] Furthermore, when the preheating procedure is executed and the dehydration stage has not yet ended, if the external ambient temperature is greater than or equal to the first preset temperature and / or the temperature at the compressor exhaust pipe is greater than the second preset temperature, the compressor is turned off and preheating is stopped.

[0024] Furthermore, there is a fan for driving the airflow circulation of the drying system; the control method also includes:

[0025] The fan of the drying system will not start before entering the drying program.

[0026] The present invention also provides a washer-dryer for executing the above-mentioned control method of a washer-dryer, comprising a housing, and an inner drum and an outer drum arranged in the housing, and also comprising a drying system, the drying system comprising a heat pump system, an air duct and a fan for driving air circulation, and the drying system is connected to the outer drum through the air duct.

[0027] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0028] 1. The present invention adds a preheating program before the drying program, so that the expected drying temperature can be reached more quickly when entering the drying program, without the need for an additional auxiliary heating system, thus saving costs, without increasing the load on the power cord of the whole machine, and without a significant change in the energy consumption of the whole machine.

[0029] 2. When judging whether to execute the preheating procedure, the preheating control method of the present invention, when the temperature at the compressor exhaust pipe is greater than the second preset temperature, in order to prevent the compressor from overheating, the preheating procedure is not executed, and / or when the power of the motor is greater than the preset power, in order to prevent the whole machine current from exceeding the limit, the preheating procedure is not executed, which can improve the stability of the overall equipment operation.

[0030] 3. During the dehydration stage and when executing the preheating procedure, if the temperature at the compressor exhaust pipe is detected to be greater than the second preset temperature, the preheating procedure is terminated to prevent the compressor from overheating; if the power of the motor is greater than the preset power, the preheating procedure is terminated to prevent the current of the entire machine from exceeding the limit.

[0031] 4. The compressor speed in the preheating stage of the present invention is proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature, which is conducive to the temperature reaching a predetermined value before entering the drying program. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0033] Figure 1 It is the overall flow chart of the washing and drying program operation in the present invention;

[0034] Figure 2 is a flow chart of the steps of the preheating procedure in the present invention;

[0035] Figure 3 A flowchart of the steps for determining whether to start the preheating program in the present invention;

[0036] Figure 4 This is a flow chart of the interruption conditions when performing the preheating procedure in the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0038] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] like Figure 1-3 As shown, the present invention provides a control method for a washer-dryer, including a drying program, and the control method includes the following steps:

[0041] Before the drying process is executed, obtain the external environment temperature;

[0042] If the external environment temperature is lower than the first preset temperature, the compressor of the heat pump system is started to preheat the condenser.

[0043] Specifically, in order to prevent the compressor from overheating and causing safety hazards, the control method of the washer-dryer sets a protection logic:

[0044] Before the drying process is executed, obtain the temperature at the compressor exhaust pipe;

[0045] If the temperature at the compressor exhaust pipe is lower than the second preset temperature, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed.

[0046] Preferably, before the drying program is executed, if the external environment temperature is greater than or equal to the first preset temperature, and / or the temperature at the compressor exhaust pipe is greater than or equal to the second preset temperature, the compressor is not started before the drying program is executed.

[0047] Preferably, the control method of the washer-dryer also includes a washing program, which includes a washing stage and a dehydration stage. When the dehydration speed in the dehydration stage of the washing program reaches the maximum speed, the external ambient temperature and the temperature at the compressor exhaust pipe are obtained; if the external ambient temperature is lower than a first preset temperature and the temperature at the compressor exhaust pipe is lower than a second preset temperature, then before the drying program is executed, the compressor of the heat pump system is started to preheat the heat pump system, specifically, the condenser is preheated.

[0048] Preferably, in order to prevent the load on the power circuit from causing safety hazards, in this embodiment, the start timing of the preheating program is set when the dehydration speed in the dehydration stage of the washing program reaches the maximum speed.

[0049] Specifically, when the spin speed in the spin stage of the washing program reaches the maximum speed, the motor power is obtained;

[0050] If the motor power is less than the preset power, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed;

[0051] If the motor power is greater than the preset power, the compressor of the heat pump system is started when the motor stops running, that is, the compressor is started when the drying program is executed.

[0052] Specifically, when measuring the motor power, it is also necessary to choose the stage when the speed reaches the maximum speed during the dehydration phase. On the one hand, the measurement is performed when the drum of the dehydration program is at the highest speed. At this time, the drum rotates at a high speed and has higher stability than when the drum just starts to turn. On the other hand, when the speed has not reached the maximum speed during the dehydration phase, the motor power is not the largest at this time. If the motor power is obtained at this time and compared with the preset power, it is easy to cause the preset power to be exceeded when the motor power is maximum. At this time, the preheating program has been started, and the sum of the motor power and the compressor power exceeds the rated power of the whole machine, thereby causing the whole machine current to exceed the limit.

[0053] Specifically, when the condenser is preheated, the rotation speed of the compressor is lower than the rotation speed of the compressor after entering the drying program.

[0054] Specifically, the speed of the compressor is variable. When the preheating program is executed during preheating, the speed of the compressor is within a range less than the set speed of the drying program, and the speed of the compressor is changed according to the actual temperature conditions.

[0055] Specifically, during the preheating process of the condenser, the speed of the compressor is directly proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature, that is, the greater the difference between the external ambient temperature and the first preset temperature, the faster the speed of the compressor; the smaller the difference between the external ambient temperature and the first preset temperature, the slower the speed of the compressor; the greater the difference between the temperature at the compressor exhaust pipe and the second preset temperature, the faster the speed of the compressor; the smaller the difference between the temperature at the compressor exhaust pipe and the second preset temperature, the slower the speed of the compressor.

[0056] Specifically, the duration of the dehydration stage is fixed. During the preheating process of the condenser, the speed of the compressor is set to be proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature. The temperature can be effectively controlled to reach the temperature required for drying at the end of dehydration.

[0057] Specifically, in actual use, due to changes in ambient temperature or other external factors, the temperature of the drying system may reach the temperature for entering the drying program before the dehydration stage is completed. At this time, in order to prevent the compressor from overheating or the temperature is too high, the following control logic is set.

[0058] Specifically, when the preheating procedure is executed and the dehydration stage has not yet ended, if the external ambient temperature is greater than or equal to the first preset temperature and / or the temperature at the compressor exhaust pipe is greater than the second preset temperature, the compressor is turned off and the preheating is stopped.

[0059] Specifically, it also has a fan for driving the air circulation of the drying system; the control method also includes: before entering the drying program, the fan of the drying system is not started. The function of the fan is to provide circulating airflow during drying and it does not need to be turned on during the preheating stage.

[0060] Specifically, the steps of the preheating procedure include:

[0061] S1, start the compressor and run it at a speed lower than the compressor of the drying program;

[0062] S2, do not start the fan and keep running in the current state;

[0063] S3, the preheating process ends, the fan is started, and the compressor speed is increased to enter the drying process.

[0064] Specifically, in the present invention, the steps of determining whether to start the preheating program are:

[0065] S11, obtaining the external environment temperature and comparing it with the first preset temperature:

[0066] If the temperature is greater than the first preset temperature, the preheating program will not start;

[0067] If the temperature is lower than the first preset temperature, the next step is executed;

[0068] S12, when the maximum speed of the dehydration program is reached, the temperature at the exhaust pipe of the compressor and the motor power are obtained, and compared with the second preset temperature and the preset power respectively:

[0069] If the temperature at the compressor exhaust pipe and / or the motor power is greater than the second preset temperature and preset power, the preheating procedure will not be started;

[0070] If the temperature at the compressor exhaust pipe and the motor power are less than the second preset temperature and the preset power, the next step is executed;

[0071] S13, the preheating program starts.

[0072] Specifically, for the first preset temperature, the second preset temperature and the preset power, it is necessary for users or professionals to manually set the parameters according to the actual environment and different whole machine systems.

[0073] Embodiment 1

[0074] like Figure 1-3 As shown, in an embodiment of the present invention, a washer-dryer that can execute the control method of a washer-dryer mentioned in the present invention is introduced, the washer-dryer includes a housing, a drainage pump, an inner drum, an outer drum and a drying system, the drying system includes a heat pump system, an air duct and a fan for driving air circulation, and the drying system is connected to the outer drum through the air duct.

[0075] Specifically, the air duct includes an air inlet duct and a return air duct. One end of the air inlet duct is connected to the outer cylinder, and the other end is connected to the heat pump system; one end of the return air duct is connected to the outer cylinder, and the other end is connected to the heat pump system. The circulating airflow of the heat pump system is blown into the outer cylinder from the air inlet duct, and then blown into the return air duct from the outer cylinder to form a cycle. The air blown into the outer cylinder from the air inlet duct is dry hot air, and the air blown into the return air duct from the outer cylinder is humid hot air.

[0076] Specifically, temperature sensors are provided on the outside of the washer-dryer housing and at the exhaust pipe of the compressor. The temperature sensors may be thermocouple temperature sensors, thermal resistor temperature sensors, thermistor temperature sensors or infrared temperature sensors, but are not limited to the above-mentioned sensors. Other suitable sensors that can achieve the same effect can be selected as the embodiment. The temperature sensor can be installed at an installation position or in an installation quantity according to actual needs, thereby improving the accuracy of temperature measurement.

[0077] Specifically, the temperature sensor arranged on the outside of the washer-dryer casing is a first temperature sensor, and the measured temperature is a first temperature. The first temperature is compared with a first preset temperature. When the first temperature is greater than or equal to the first preset temperature, the washer-dryer is in a normal temperature or high ambient temperature environment, and this temperature does not affect the normal heating of the drying system, and the preheating program is not started at this time; when the first temperature is lower than the first preset temperature, the washer-dryer is in a low temperature environment, and the temperature inside the machine body is low at this temperature, and the temperature rises slowly when the drying program is executed, and the preheating program needs to be executed at this time.

[0078] Specifically, in actual use, the user may use the washer-dryer to run the drying program for multiple times in a row. At this time, the temperature of the compressor exhaust pipe cannot be lowered in a short period of time. Even if the external ambient temperature is low, the temperature inside the machine can still reach the preset temperature for the normal operation of the drying program due to the continuous operation of the compressor. At this time, turning on the preheating program will cause the compressor to overheat, so a preheating protection program is required.

[0079] Specifically, the temperature sensor arranged at the exhaust pipe of the compressor is a second temperature sensor, and the measured temperature is the second temperature. The second temperature is compared with the second preset temperature. When the second temperature is greater than or equal to the second preset temperature, the internal temperature of the washer-dryer can reach the minimum temperature for executing the drying program. At this temperature, it does not affect the normal heating of the drying system, and the preheating program is not started at this time; when the second temperature is lower than the second preset temperature, the temperature inside the machine body is low at this temperature, and the temperature rises slowly when the drying program is executed. At this time, the preheating program needs to be executed.

[0080] Specifically, the second temperature sensor is not limited to being installed at the exhaust pipe of the compressor, and other suitable locations that can achieve the same effect can be selected as the embodiment.

[0081] Specifically, the washer-dryer is equipped with a motor drive board for controlling the motor and detecting the power of the motor.

[0082] Specifically, when the washer-dryer is executing the washing and drying mode, in order to prevent the current of the whole machine from exceeding the limit, it is necessary to obtain the motor power during the dehydration stage when the inner drum speed is the highest and the motor power is also the largest, and compare it with the preset power. When the motor power is greater than or equal to the preset power, the current of the whole machine is relatively large. In order to prevent the current of the whole machine from exceeding the limit, the preheating program is not executed at this time; if the motor power is less than the preset power, the current of the whole machine is within a safe range. When the first temperature is less than the first preset temperature and the second temperature is less than the second preset temperature, the preheating program is executed.

[0083] Embodiment 2

[0084] like Figure 4 As shown, in this embodiment, an interrupt program is introduced. In daily use, when executing the preheating stage, the temperature reaches the temperature required for entering the drying stage in advance. At this time, the dehydration stage has not ended and the drying stage cannot be entered directly. Therefore, an interrupt logic is set to prevent the compressor from overheating or the whole machine current from exceeding the limit.

[0085] Specifically, when the preheating procedure is executed and the dehydration stage has not ended, the second temperature sensor continuously detects the temperature at the compressor exhaust pipe, and when the second temperature value is greater than the second preset temperature, the preheating procedure is terminated.

[0086] Preferably, when the second temperature is equal to the second preset temperature, the preheating program is continued to be executed to prevent the situation in which the temperature drops too much after stopping the preheating and before entering the drying program, resulting in insufficient temperature when entering the drying program.

[0087] Specifically, when the preheating program is executed and the dehydration stage has not yet ended, the motor drive board continuously monitors the power of the motor. When the motor power value is greater than or equal to the preset power, the preheating program is terminated. In order to prevent the current of the entire machine from exceeding the limit, the preheating program needs to be terminated when the motor power reaches the preset power.

[0088] Preferably, the speed of heating can also be controlled by setting the speed of the compressor in the preheating program to ensure that the temperature will not be overheated at the end of the dehydration stage.

[0089] Specifically, during the preheating process of the condenser, the speed of the compressor is directly proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature, that is, the greater the difference between the external ambient temperature and the first preset temperature, the faster the speed of the compressor; the smaller the difference between the external ambient temperature and the first preset temperature, the slower the speed of the compressor; the greater the difference between the temperature at the compressor exhaust pipe and the second preset temperature, the faster the speed of the compressor; the smaller the difference between the temperature at the compressor exhaust pipe and the second preset temperature, the slower the speed of the compressor.

[0090] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. A control method for a washer-dryer, comprising a drying program, characterized in that: The control method comprises the following steps: Before the drying process is executed, obtain the external environment temperature; If the external environment temperature is lower than the first preset temperature, the compressor of the heat pump system is started to preheat the condenser.

2. The control method of a washer-dryer according to claim 1, characterized in that: Also includes: Before the drying process is executed, obtain the temperature at the compressor exhaust pipe; If the temperature at the compressor exhaust pipe is lower than the second preset temperature, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed.

3. The control method of a washer-dryer according to claim 2, characterized in that: Before the drying program is executed, if the external environment temperature is greater than or equal to the first preset temperature, and / or the temperature at the compressor exhaust pipe is greater than or equal to the second preset temperature, the compressor is not started before the drying program is executed.

4. A control method for a washer-dryer according to any one of claims 1 to 3, characterized in that: The washing program is also included. When the dehydration speed in the dehydration stage of the washing program reaches the maximum speed, the external environment temperature and the temperature at the exhaust pipe of the compressor are obtained; If the external environment temperature is lower than the first preset temperature and the temperature at the compressor exhaust pipe is lower than the second preset temperature, the compressor of the heat pump system is started to preheat the condenser before the drying program is executed.

5. The control method of a washer-dryer according to claim 4, characterized in that: When the spin speed in the spin stage of the washing program reaches the maximum speed, the motor power is obtained; If the motor power is less than the preset power, the compressor of the heat pump system is started to preheat the condenser before the drying process is executed; If the motor power is greater than the preset power, the compressor will not start before the drying process is executed.

6. A control method for a washer-dryer according to any one of claims 1 to 3, characterized in that: When preheating the condenser, the speed of the compressor is lower than the speed of the compressor after entering the drying program.

7. A control method for a washer-dryer according to claim 6, characterized in that: During the preheating process of the condenser, the rotation speed of the compressor is proportional to the difference between the external ambient temperature and the first preset temperature, and the difference between the temperature at the compressor exhaust pipe and the second preset temperature.

8. The control method of a washer-dryer according to claim 6, characterized in that: When the preheating procedure is executed and the dehydration stage has not yet ended, if the external ambient temperature is greater than or equal to the first preset temperature and / or the temperature at the compressor exhaust pipe is greater than the second preset temperature, the compressor is turned off and the preheating is stopped.

9. A control method for a washer-dryer according to any one of claims 1 to 3, characterized in that: A fan is also provided for driving airflow circulation of the drying system; and the control method further comprises: The fan of the drying system will not start before entering the drying program.

10. A washer-dryer for executing the control method of the washer-dryer according to any one of claims 1 to 9, characterized in that: It includes a box body, an inner cylinder and an outer cylinder arranged in the box body, and a drying system. The drying system includes a heat pump system, an air duct and a fan for driving air circulation. The drying system is connected with the outer cylinder through the air duct.

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