dryer

Abstract

The present invention relates to a dryer, comprising: a main body having an inlet; a drum rotatably arranged on the main body; a drive motor providing rotational power to the drum; a blower fan forcing air to flow toward the main body; a heat pump system comprising a condenser, an evaporator, and a compressor for heating the air supplied to the drum; an external air temperature sensor for measuring the external temperature; and a control unit for comparing the external temperature with a preset reference temperature to control a plurality of operating modes, wherein, when the external temperature is lower than the reference temperature, the control unit forcibly drives the compressor at an operating frequency higher than that of the selected operating mode.

Description

[0001] This case is a divisional application of the invention patent application with the application date of November 13, 2018, application number 201880073441.0, and name “Control method of dryer”. Technical Field

[0002] The present invention relates to a drying machine. Background Art

[0003] Generally, a clothes treating apparatus having a drying function, such as a washing machine or a dryer, is a device that supplies hot air to wet clothes to evaporate moisture from the clothes.

[0004] For example, a dryer may include a drum, a drive motor, a blower fan, and a heating element. The drum is rotatably mounted inside the main body and receives laundry; the drive motor drives the drum; the blower fan blows air into the drum; and the heating element heats the air flowing into the drum.

[0005] Dryers, on the other hand, can be categorized as either circulation-type or exhaust-type dryers, depending on how they exhaust the hot, humid air. The air flowing out of the drum absorbs moisture from the laundry inside, becoming hot and humid. Circulation-type dryers circulate the hot, humid air without exhausting it outside the dryer. Instead, heat exchangers cool the air to below its dew point, condensing the moisture in the hot, humid air before resupplying it. Exhaust-type dryers, on the other hand, exhaust the hot, humid air flowing out of the drum directly to the outside.

[0006] On the other hand, as a heating method of the heating member, there are possible methods of utilizing high-temperature resistance heat generated by an electric resistor or utilizing combustion heat generated by combustion gas.

[0007] Alternatively, the heating means may include a heat pump system comprising a heat exchanger, a compressor, and an expander, wherein the refrigerant in the circulation system recovers energy from the hot air discharged from the drum and heats the air supplied to the drum, thereby improving energy efficiency.

[0008] Specifically, the heat pump system features an evaporator on the exhaust side of the drum and a condenser on the inlet side. After heat energy is absorbed by the refrigerant in the evaporator, it is heated to a high temperature and high pressure by the compressor. The refrigerant's heat energy is then transferred to the air flowing into the drum via the condenser, generating heat products from the wasted energy.

[0009] Recently, dryers using heat pump systems with higher energy efficiency are being actively developed.

[0010] Korean Patent Publication No. 10-2013-0101912, which is a prior art document, discloses a dryer using a heat pump system.

[0011] On the other hand, when using a heat pump system in a dryer, if the outside temperature is low, the refrigerant may not be heated sufficiently, and thus the incoming air may not be heated sufficiently, which may result in a significant reduction in the dryer's drying performance. Therefore, it is necessary to develop a technology that can improve air heating performance according to the outside temperature.

[0012] According to the prior art documents, there is no disclosure that the heating performance can be improved according to the external temperature when the external temperature is low. Therefore, there is a possibility that the drying performance is reduced when the external temperature is low.

[0013] Furthermore, according to prior art literature, although a high-speed drying mode is provided that uses a heater as a heat source in addition to a heat pump system to improve drying performance, the need to additionally install a heater may result in a significant increase in manufacturing costs and increased power consumption.

[0014] On the other hand, when the heat pump system is applied to the dryer, the capacity of the compressor for compressing the refrigerant to produce high temperature plays an important role in the performance of the system.

[0015] However, due to the limited space inside dryers, increasing the compressor size to increase capacity is inherently limited. Furthermore, while increasing compressor capacity improves refrigerant compression performance, it also increases vibration and noise, potentially significantly reducing user satisfaction. Therefore, there is a need to develop heat pump systems that produce minimal vibration while delivering sufficient performance. Summary of the Invention

[0016] Problems to be solved by the invention

[0017] An object of the present invention is to provide a control method for a dryer to which a heat pump system is applied, which can effectively exert the drying performance of the dryer in a low-temperature usage environment.

[0018] Another object of the present invention is to provide a control method for a dryer to which a heat pump system is applied, which can reduce noise and vibration during driving.

[0019] Technical solutions to problems

[0020] According to an embodiment of the present invention, a dryer includes: a main body having an inlet; a drum rotatably arranged on the main body; a drive motor providing rotational power to the drum; a blower fan forcing air to flow toward the main body; a heat pump system including a condenser, an evaporator, and a compressor for heating the air supplied to the drum; an external air temperature sensor for measuring the external temperature; and a control unit for comparing the external temperature with a preset reference temperature to control multiple operating modes, wherein when the external temperature is lower than the reference temperature, the control unit forcibly drives the compressor at a higher operating frequency than that of the selected operating mode.

[0021] A control method for a dryer according to an embodiment of the present invention is provided for controlling a dryer having a heat pump system, the heat pump system being a heat source for heating air supplied to a drum. The control method comprises: a step (S10) in which a user selects one of a plurality of operating modes having different initial drive frequencies for the compressor and inputs a drying start command to the dryer; a step (S20) in which a control unit confirms an external temperature and compares the external temperature with a preset external air reference temperature T; a step (S45) in which the control unit executes the operating mode selected by the user if the external temperature is above the external air reference temperature T; and a step (S50) in which the control unit determines that the operating environment of the dryer is in a low temperature state and executes the operating mode having the highest initial drive frequency for the compressor among the plurality of operating modes, if the external temperature is below the external air reference temperature T.

[0022] In addition, it is characterized in that the multiple operating modes include: a speed mode, in which the initial driving frequency and the variable minimum frequency of the compressor are the highest; a standard mode, in which the initial driving frequency and the variable minimum frequency of the compressor are lower than the speed mode; and an energy-saving mode, in which the initial driving frequency and the variable minimum frequency of the compressor are lower than the standard mode.

[0023] In addition, the control method of the dryer is characterized in that it further includes: a step of confirming the outlet side temperature of the compressor in the control unit and comparing it with a preset reference temperature C1 (S60); when the outlet side temperature of the compressor is higher than the reference temperature C1, the control unit determines that the compressor is in an overloaded state, thereby executing a low-speed mode, in which the compressor operates at a lower variable frequency than the variable minimum frequency of the compressor in the operating mode being executed (S70).

[0024] Furthermore, the present invention is characterized in that in the low speed mode, the variable minimum frequency of the compressor is lower than the variable minimum frequency in the operation mode.

[0025] Furthermore, it is characterized in that, in the low-speed mode, the lowest frequency of the compressor is greater than 0 Hz.

[0026] Furthermore, the invention is characterized in that when the control unit confirms that the outlet temperature of the compressor is lower than the reference temperature C1 during the execution of the low speed mode, the control unit cancels the low speed mode and returns to the initial operation mode before the execution of the low speed mode.

[0027] Furthermore, the invention is characterized in that, in the low speed mode, the control unit checks the outlet temperature of the compressor at a predetermined period and gradually reduces the frequency of the compressor by a set frequency reduction value H2.

[0028] In addition, it is characterized in that the control method of the dryer also includes: when one of the multiple operation modes is being executed, the control unit compares the outlet side temperature of the compressor with a preset reference temperature C2 to determine whether the temperature inside the drum has reached a temperature state suitable for drying; when the outlet side temperature of the compressor is above the reference temperature C2, the control unit determines that the temperature inside the drum has reached a temperature suitable for drying, and reduces the frequency of the compressor to maintain the temperature.

[0029] In addition, it is characterized in that when one of the multiple operation modes is being executed, the control unit confirms at a predetermined period whether the outlet side temperature of the compressor is above the reference temperature C2, and gradually reduces the frequency of the compressor by a set frequency reduction value H1.

[0030] Furthermore, it is characterized in that the frequency reduction value H2 is greater than the frequency reduction value H1.

[0031] Furthermore, the invention is characterized in that the compressor is a twin-rotor compressor.

[0032] Furthermore, the present invention is characterized in that R134a refrigerant is used as the refrigerant of the heat pump system.

[0033] Effects of the Invention

[0034] In the dryer according to the embodiment of the present invention, the following effects can be expected.

[0035] First, if the outside temperature is lower than the reference temperature T, the control unit determines that the dryer is operating in a low-temperature environment. The control unit then ignores the user-selected operating mode and forcibly executes the operating mode with the highest initial compressor drive frequency among the multiple operating modes. Therefore, when the outside temperature is low, the heat pump system can fully utilize its heating performance, preventing excessively long drying times. This prevents user dissatisfaction with the dryer's performance.

[0036] Second, the control unit checks the compressor outlet temperature. If it is above a reference temperature C1, the compressor is determined to be overloaded and enters low-speed mode. In this low-speed mode, the compressor is decelerated to a frequency lower than the compressor's minimum variable frequency in the currently operating mode, thereby reducing the compressor load. This prevents damage to the compressor due to excessive heat.

[0037] Third, in low-speed mode, the lowest frequency of the compressor is greater than 0 Hz. That is, when the compressor is overloaded, it runs at a low speed, thereby continuously heating the air. Therefore, the drying performance can be improved.

[0038] Fourth, in low-speed mode, the control unit checks the compressor outlet temperature at a predetermined interval and gradually reduces the compressor outlet temperature. This prevents the compressor from rapidly cooling down and reducing heating performance, allowing optimal performance to be achieved while reducing the load.

[0039] Fifth, the use of a twin-rotor compressor minimizes vibration and noise at both high and low frequencies. This maintains user-satisfactory vibration and noise levels, while also expanding the compressor's maximum and minimum frequency ranges. This further enhances the frequency range of the low-speed mode, where the minimum frequency is lower than that of the aforementioned operating mode. Furthermore, the ability to increase the maximum frequency further enhances drying performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a perspective view of a drying machine according to an embodiment of the present invention.

[0041] Figure 2 It is a schematic diagram showing the internal structure of the dryer according to the embodiment of the present invention.

[0042] Figure 3 1 is a structural diagram showing the main components of a dryer according to an embodiment of the present invention.

[0043] Figure 4 1 is a flowchart showing a control method of the dryer 1 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following and attached Figure 1 The specific embodiments of the present invention are described in detail. However, the concept of the present invention is not limited to the embodiments mentioned above, and other inventions or other embodiments within the scope of the concept of the present invention can be easily proposed by adding, changing, deleting, and other constituent elements.

[0045] Figure 11 is a perspective view of a dryer according to an embodiment of the present invention. Figure 2 1 is a schematic diagram showing the internal structure of a dryer according to an embodiment of the present invention. Figure 3 1 is a structural diagram showing the main components of a dryer according to an embodiment of the present invention.

[0046] The dryer 1 according to the embodiment of the present invention may include: a main body 10 having an inlet 11 for inserting clothes formed on one side thereof; and a door 20 for opening and closing the inlet 11 to form an overall appearance.

[0047] A drum 15 for drying clothes may be rotatably mounted inside the main body 10 . The drum 15 opens toward the inlet 11 , so that a user can put clothes into the drum 15 through the inlet 11 .

[0048] The main body 10 may be provided with an operating unit 12 for operating the dryer 1. The operating unit 12 may be located above the inlet 11.

[0049] The operating unit 12 may be provided with operating buttons, a rotary switch, etc. for selecting functions provided to the dryer 1. For example, a user may operate the operating buttons or the rotary switch provided on the operating unit 12 to turn the power of the dryer 1 on / off, input a start or stop command, or set an operation mode and drying time.

[0050] The operation unit 12 may further include a display unit 13. The display unit 13 may output the operating state of the dryer 1, a set operating mode, time information, and the like.

[0051] A drawer 14 may be provided on one side of the main body 10 , and liquid to be sprayed into the drum may be stored inside the drawer 14 .

[0052] The main body 10 may be provided with a drive motor 300 for providing rotational power to the drum 15. A power transmission member 360 for rotating the drum 15 may be provided on a rotation shaft of the drive motor 300. The drum 15 is connected to the drive motor 300 via the power transmission member 360, thereby receiving power transmission. The power transmission member 360 may be a pulley or a roller.

[0053] The main body 10 may be provided with a duct forming a supply flow path for supplying heated air to the drum 15 and an exhaust flow path for exhausting air inside the drum 15. The duct may include a supply duct 30 forming the supply flow path and an exhaust duct 40 forming the exhaust flow path.

[0054] In addition, a blower fan 50 for forcing air to flow may be further provided in the main body 10. The blower fan 50 may be in communication with the supply duct 30 and the exhaust duct 40, thereby forcing air to be supplied to the interior of the drum 15 through the supply duct 30, and the air inside the drum 15 to be exhausted through the exhaust duct 40.

[0055] The blower fan 50 may be provided on the exhaust flow path to draw the air exhausted from the drum 15 into the exhaust duct 40 .

[0056] The blower fan 50 may be connected to the rotating shaft of the driving motor and rotate together with the drum 15. Of course, the blower fan 50 may be connected to a motor provided separately from the driving motor and rotate independently of the drum 15.

[0057] On the other hand, in the embodiments of the present invention, a circulation type dryer in which air inside the dryer circulates is described as an example. However, the present invention is not limited to the circulation type dryer and can also be applied to an exhaust type dryer.

[0058] If the dryer 1 is a circulation type dryer, the exhaust duct 40 may guide the forced air to the supply duct 30 .

[0059] On the other hand, if the dryer 1 is an exhaust type dryer, the exhaust duct 40 may guide the forced air to the outside.

[0060] The supply duct 30 may extend to the rear side of the drum 15 and be provided at an end thereof with an exhaust port for exhausting heated air into the drum.

[0061] The exhaust duct 40 may extend to the front lower side of the drum 15 and may have an inlet formed at an end thereof for sucking air into the drum.

[0062] A heater (not shown) may be further provided on the supply flow path of the supply duct 30 to heat the supplied air by resistive heat. The provision of the heater can further improve the heating characteristics of the supplied air.

[0063] A filter 45 may be provided on an exhaust flow path of the exhaust duct 40 . The filter 45 filters foreign matter such as lint contained in the air exhausted from the drum 15 .

[0064] On the other hand, a heat pump system 100 may be provided in the main body 10 . The heat pump system 100 absorbs waste heat from the air exhausted from the drum 15 and heats the air supplied to the drum 15 .

[0065] The heat pump system 100 may include an evaporator 120, a compressor 110, a condenser 130, and an expansion valve 140. The evaporator 120 is used to cool the air exhausted from the drum 15; the compressor 110 is used to compress the refrigerant; and the condenser 130 is used to heat the air supplied to the drum 15. Thus, the heat pump system 100 may constitute a thermodynamic cycle.

[0066] The evaporator 120, the compressor 110, the condenser 130, and the expansion valve 140 may be connected in sequence via pipelines, and refrigerant may circulate in the pipelines.

[0067] The refrigerant is compressed in the compressor 110 to form a high-temperature, high-pressure gas. It then becomes a high-temperature, high-pressure liquid in the condenser 130 and can exchange heat with the low-temperature air supplied to the drum 15. The refrigerant is then expanded in the expansion valve 140 to form a low-temperature, low-pressure gas. In the evaporator 120, the refrigerant can then exchange heat with the high-temperature, high-humidity air discharged from the drum 15.

[0068] The air supplied to the drum 15 is heated to a high temperature after heat exchange in the condenser 130. Furthermore, the hot, humid air exhausted from the drum 15 is cooled after heat exchange in the evaporator 120, thereby removing moisture and achieving a dry state. The moisture contained in the hot, humid air condenses and collects as water in the evaporator 120, which is then discharged to the outside through a drain pipe (not shown).

[0069] The evaporator 120 may be disposed on the exhaust flow path of the exhaust duct 40 . Also, the condenser 130 may be disposed on the supply flow path of the supply duct 30 .

[0070] A machine room for communicating the exhaust duct 40 and the supply duct 30 may be formed inside the main body 10. The compressor 110 and the expansion valve 140 may be disposed in the machine room. In addition, the drive motor may also be disposed in the machine room.

[0071] On the other hand, the dryer 1 may further include: a control unit 200 for controlling the overall operation of the dryer 1 ; and a storage unit 90 for storing information such as algorithm data and setting value data related to the operation of the dryer 1 .

[0072] In addition, the dryer 1 may further include an external air temperature sensor 70 for measuring external temperature and a compressor temperature sensor 80 for measuring the temperature of the compressor 110 .

[0073] The compressor temperature sensor 80 may measure the temperature at the outlet of the compressor 110 .

[0074] In addition, the dryer 1 may further include a humidity sensor 60. The humidity sensor 60 may be used to measure the dryness of the drying objects contained in the drum 15 or to detect whether wet clothes are put in. To this end, the humidity sensor 60 may be disposed inside the drum 15.

[0075] The operation unit 12 , the driving motor, the compressor 110 , the storage unit 90 , the outside air temperature sensor 70 , the compressor temperature sensor 80 , and the humidity sensor 60 may be electrically connected to the control unit 200 .

[0076] The control unit 200 can detect an operation signal from the operation unit 12 and confirm information corresponding to the operation signal input from the storage unit 90. Furthermore, based on the information stored in the storage unit 90, the control unit 200 can control the operation of the drive motor and compressor 110. For example, if a drying start command is input from the operation unit 12, the control unit 200 can drive the drive motor and compressor 110 to start drying. Furthermore, if a drying end command is input, the control unit 200 can stop driving the drive motor and compressor 110 to end drying.

[0077] The controller 200 may adjust the operation of the dryer 1 according to information input from the outside air temperature sensor 70 , the compressor temperature sensor 80 , and the humidity sensor 60 .

[0078] In detail, the controller 200 may differently control the operation mode of the heat pump system 100 based on the temperature input from the outside air temperature sensor 70 .

[0079] The control unit 200 may switch the operation mode of the heat pump system 100 based on the temperature input from the compressor temperature sensor 80, or adjust the driving speed of the compressor 110 to adjust the load. Figure 4 This is described in more detail in the description of .

[0080] Furthermore, the control unit 200 can determine whether wet laundry has been added based on the humidity information input from the humidity sensor 60. If wet laundry has been added, the control unit 200 can control the drive motor and the compressor 110 to operate. The control unit 200 can then determine the drying state of the laundry based on the humidity information and stop the drive motor and the compressor 110.

[0081] In addition, if the temperature inside the drum 15 reaches a suitable temperature after the compressor 110 is driven, the controller 200 may reduce the rotation speed of the compressor 110 to maintain the temperature inside the drum 15 suitable for drying.

[0082] At this time, the dryer 1 is further provided with a temperature sensor for measuring the temperature inside the drum 15 . The control unit 200 can detect the temperature inside the drum 15 through the temperature sensor for measuring the temperature inside the drum 15 .

[0083] Alternatively, the control unit 200 may determine whether the temperature inside the drum 15 has reached an appropriate temperature based on the temperature at the compressor outlet side detected by the compressor temperature sensor 80 .

[0084] Alternatively, the compressor 110 may be a twin-rotor compressor. A twin-rotor compressor may have a structure in which two refrigerant compression chambers are formed in an upper and lower direction, and two eccentric rollers are disposed within the compression chambers. The two eccentric rollers compress the refrigerant while being eccentrically rotated by a single drive shaft, and are disposed 180 degrees out of phase with each other.

[0085] The twin-rotor compressor has the following characteristics: continuous refrigerant compression occurs at the upper and lower parts by the two eccentric rollers, thereby improving the compression efficiency of the compressor and reducing vibration and noise.

[0086] Compared to a single-chamber compressor of the same volume and forming only one compression chamber, the compressor 110 can provide higher compression efficiency and reduce vibration and noise. Therefore, no additional space is required within the dryer 1 for accommodating the compressor 110. Furthermore, the compressor 110 can provide higher compression efficiency, thereby improving the drying performance of the dryer 1.

[0087] On the other hand, the driving speed of the compressor 110 can be variably controlled by the controller 200 , and the heating performance of the air can be adjusted by varying the driving speed of the compressor 110 . That is, the controller 200 can change the operating frequency (Hz) of the compressor 110 .

[0088] At this time, since the compressor 110 uses a twin-rotor compressor, it can reduce noise in the high-frequency range and vibration in the low-frequency range compared to a single-chamber compressor. Therefore, it is possible to provide user-satisfied noise and vibration levels and further expand the maximum frequency and minimum frequency.

[0089] For example, the frequency driving range of the compressor 110 can be variably controlled to be between a minimum of 30 Hz and a maximum of 90 Hz.

[0090] On the other hand, R134a can be used as the refrigerant used in the heat pump system 100. Of course, various fluids such as R245fa can also be used as the refrigerant, but in the embodiment of the present invention, an example of using R134a refrigerant is described.

[0091] Since the R134a refrigerant has a high discharge temperature, it is advantageous for heating the air supplied from the condenser 130 to the drum 15 .

[0092] On the other hand, the operation unit 12 may be provided with a mode selection unit 121 , which can select the operation mode of the dryer 1 as an energy-saving mode, a standard mode, or a speed mode.

[0093] The energy-saving mode is a mode for reducing power consumption, and therefore, the energy-saving mode may be a mode in which the initial driving frequency of the compressor 110 is the lowest among the operation modes.

[0094] The standard mode may be a mode in which the initial driving frequency of the compressor 110 is higher than the energy-saving mode and lower than the speed mode.

[0095] The speed mode is a mode for maximizing the drying performance of the dryer 1 , and thus, may be a mode in which the initial driving frequency of the compressor 110 is higher than that of the standard mode.

[0096] For example, if the dryer 1 is operated in the energy-saving mode, the compressor 110 may be initially accelerated to 50 Hz. Furthermore, if the dryer 1 is operated in the standard mode, the compressor 110 may be initially accelerated to 75 Hz. Furthermore, if the dryer 1 is operated in the speed mode, the compressor 110 may be initially accelerated to 90 Hz.

[0097] On the other hand, the energy-saving mode, the standard mode, and the speed mode may each have a variable frequency range of the compressor 110 .

[0098] If the temperature inside the drum 15 reaches a suitable temperature for drying, the compressor 110 may be controlled to reduce its frequency in order to maintain the temperature inside the drum 15 .

[0099] At this time, the control unit 200 may determine whether the temperature inside the drum 15 has reached an appropriate temperature based on the temperature measured by the compressor temperature sensor 80 .

[0100] For example, when the temperature measured by the compressor temperature sensor 80 is 85 degrees, the control unit 200 may determine that the temperature inside the drum 15 has reached the appropriate temperature. In this case, the temperature inside the drum 15 may vary depending on the operation mode, and may be highest in the speed mode and lowest in the energy-saving mode.

[0101] On the other hand, the minimum frequency of the compressor 110 in the speed mode may be higher than the minimum frequency of the compressor 110 in the standard mode. In addition, the minimum frequency of the compressor 110 in the energy-saving mode may be lower than the minimum frequency of the compressor 110 in the standard mode.

[0102] That is, the energy saving mode may be a mode in which the maximum frequency and the minimum frequency of the compressor 110 are the lowest among the operation modes. In addition, the speed mode may be a mode in which the maximum frequency and the minimum frequency of the compressor 110 are the highest among the operation modes.

[0103] For example, in the energy-saving mode, the variable frequency range of the compressor 110 may be 50 Hz to 35 Hz. In the standard mode, the variable frequency range of the compressor 110 may be 75 Hz to 48 Hz. In the speed mode, the variable frequency range of the compressor 110 may be 90 Hz to 60 Hz.

[0104] The user can select an operation mode from the energy-saving mode, standard mode and speed mode by operating the operation unit 12. For example, if the user wishes to reduce power consumption, the energy-saving mode can be selected, and if the user wishes to dry the clothes quickly, the speed mode can be selected.

[0105] The control unit 200 may control the heat pump system 100 in different ways depending on the operation mode selected by the user.

[0106] On the other hand, when the external temperature is lower than the predetermined temperature, the control unit 200 determines that the external temperature is low, and thus ignores the operation mode selected by the user and controls the dryer 1 to operate in the speed mode.

[0107] On the other hand, if the control unit 200 determines that the compressor 110 is overheated, the control unit 200 may switch the dryer 1 to a low-speed mode in order to prevent damage to the compressor 110 .

[0108] The low speed mode may be defined as a mode in which the compressor 110 operates at a frequency lower than the lowest frequency of the currently executed operation mode.

[0109] For example, when the compressor 110 is operating in the speed mode, if the low speed mode is executed, the frequency of the compressor 110 may be controlled to be lower than the minimum frequency of 60 Hz in the speed mode. Furthermore, when the compressor 110 is operating in the energy-saving mode, if the low speed mode is executed, the frequency of the compressor 110 may be controlled to be lower than the minimum frequency of 35 Hz in the energy-saving mode.

[0110] In the low-speed mode, the frequency of the compressor 110 may be lower than the minimum frequency of 35 Hz in the energy-saving mode, for example, it may be reduced to a minimum of 30 Hz.

[0111] On the other hand, if the low-speed mode is executed, the frequency of the compressor 110 may be controlled to gradually decelerate to the minimum frequency of 30 Hz in the low-speed mode of the compressor 110. Alternatively, the frequency of the compressor 110 may be controlled to immediately decelerate to the minimum frequency of 30 Hz in the low-speed mode and then maintain the minimum frequency.

[0112] The control method of the dryer 1 according to the embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0113] Figure 4 is a flowchart illustrating a method for controlling the dryer 1 according to an embodiment of the present invention.

[0114] The user may operate the operation unit 12 to input an operation command to the dryer 1. At this time, the user may select an operation mode among the energy saving mode, the standard mode, and the speed mode by operating the operation unit 12 (S10).

[0115] If an operation command is input to the dryer 1, the control unit 200 may confirm the external temperature. The external temperature may be measured by the external air temperature sensor 70. The measured external temperature may be transmitted to the control unit 200. Accordingly, the control unit 200 may detect the external temperature (S20).

[0116] The control unit 200 may compare the detected external temperature with a preset reference temperature T. Specifically, the control unit 200 may determine whether the detected external temperature is equal to or greater than the reference temperature T or less than the reference temperature T. The reference temperature T may be stored and provided in the storage unit 90 .

[0117] The reference temperature T may be a temperature lower than 10 degrees, for example, may be set to 5 degrees Celsius ( S30 ).

[0118] If the external temperature is greater than or equal to the reference temperature T, the controller 200 may confirm the operation mode selected by the user, that is, the operation mode selected by the user from among the energy-saving mode, the standard mode, and the speed mode ( S40 ).

[0119] Furthermore, if the external temperature is equal to or higher than the reference temperature T, the controller 200 determines that the temperature is normal, and thus operates the dryer 1 in the operation mode selected by the user.

[0120] For example, if the user selects the energy-saving mode, the compressor 110 may be initially accelerated to 50 Hz to drive the heat pump system 100. Then, the blower fan 50 and the drum 15 may be operated to complete drying with lower power consumption.

[0121] If the user selects the standard mode, the compressor 110 may be initially accelerated to 75 Hz to drive the heat pump system 100. Then, the blower fan 50 and the drum 15 may be activated to complete the drying.

[0122] If the user selects the speed mode, the compressor 110 may be initially accelerated to 90 Hz to drive the heat pump system 100. Then, the blower fan 50 and the drum 15 may be activated to improve the heating characteristics of the air supplied to the drum 15. Thus, drying can be completed quickly.

[0123] On the other hand, if the control unit 200 determines that the temperature inside the drum 15 has reached a suitable temperature for drying, the frequency of the compressor 110 may be gradually reduced to a prescribed level.

[0124] At this time, the control unit 200 compares the temperature measured by the compressor temperature sensor 80 with a preset reference temperature C2. If the temperature measured by the compressor temperature sensor 80 reaches the reference temperature C2, it is determined that the temperature inside the drum 15 has reached an appropriate temperature. For example, the reference temperature C2 may be 85 degrees Celsius.

[0125] The control unit 200 continuously checks the temperature measured by the compressor temperature sensor 80 at a predetermined period, and may reduce the frequency of the compressor 110 by a set frequency reduction value H1 each time the temperature reaches the reference temperature C2.

[0126] At this time, the set frequency reduction value H1 may be 1 Hz.

[0127] In the energy-saving mode, the frequency of the compressor 110 may be reduced to 35 Hz. In addition, in the standard mode, the frequency of the compressor 110 may be reduced to 48 Hz. In addition, in the speed mode, the frequency of the compressor 110 may be reduced to 60 Hz ( S45 ).

[0128] Conversely, if the external temperature is lower than the reference temperature T, the control unit 200 may determine that the operating environment of the dryer 1 is in a low-temperature state. Therefore, the control unit 200 may ignore the operating mode selected by the user and operate the dryer 1 in the speed mode. That is, when the external temperature is lower than the reference temperature T, the dryer 1 will operate in the speed mode even if the user has selected the energy-saving mode or the standard mode.

[0129] At this time, the controller 200 may initially accelerate the compressor 110 to 90 Hz to drive the heat pump system 100. Then, the blower fan 50 and the drum 15 are operated to improve the heating characteristics of the air supplied to the drum 15, thereby quickly completing drying.

[0130] Furthermore, as in step S45 , if the control unit 200 determines that the internal temperature of the drum 15 has reached a suitable temperature for drying, the frequency of the compressor 110 may be gradually reduced to a prescribed level ( S50 ).

[0131] On the other hand, if the compressor 110 is overheated, a problem of damage to the compressor 110 may occur.

[0132] To prevent such a situation, the control unit 200 may determine whether the compressor 110 is overheated.

[0133] The control unit 200 may determine the overheating state of the compressor 110 based on the surface temperature of the compressor 110 . In this case, an additional temperature sensor for measuring the surface temperature of the compressor 110 may be further provided.

[0134] Alternatively, the control unit 200 may also determine the overheating state of the compressor 110 based on the outlet temperature of the compressor 110 detected by the compressor temperature sensor 80 .

[0135] Hereinafter, an example will be described in which the controller 200 determines the overheating state of the compressor 110 and whether the compressor 110 is overheated based on the outlet temperature of the compressor 110 .

[0136] The controller 200 may compare the temperature detected by the compressor temperature sensor 80 with a preset reference temperature C1 to determine whether the outlet temperature of the compressor 110 is equal to or lower than the reference temperature C1.

[0137] The reference temperature C1 may be stored and provided in the storage unit 90 and may be a temperature value higher than the reference temperature C2. For example, the reference temperature C1 may be set to 95 degrees (S60).

[0138] If the outlet temperature of the compressor 110 is higher than the reference temperature C1, the controller 200 may execute a low-speed mode to prevent damage to the compressor 110 due to overheating.

[0139] As described above, the low speed mode may be defined as a mode in which the compressor 110 is operated at a frequency lower than the minimum frequency of the currently executed operation mode.

[0140] If the low speed mode is executed, the frequency of the compressor 110 may be controlled to gradually decelerate to the minimum frequency of 30 Hz in the low speed mode of the compressor 110. Alternatively, the frequency of the compressor 110 may be controlled to immediately decelerate to the minimum frequency of 30 Hz in the low speed mode and then maintain the minimum frequency.

[0141] When gradually decreasing the frequency of the compressor 110, the controller 200 may continuously check the outlet temperature of the compressor 110 at a predetermined period. If the outlet temperature of the compressor 110 is equal to or higher than the reference temperature C2, the frequency of the compressor 110 may be decreased by a set frequency reduction value H2. In this case, the set frequency reduction value H2 may be 5 Hz (S70).

[0142] On the other hand, if the outlet temperature of the compressor 110 is lower than the reference temperature C1, the controller 200 may control the compressor 110 to continue operating in the initial operation mode being executed. The initial operation mode is an operation mode when the dryer 1 is initially driven, and may be any one of the energy-saving mode, the standard mode, and the speed mode.

[0143] Furthermore, after the low-speed mode is executed, the control unit 200 may continue to check the outlet temperature of the compressor 110. Furthermore, if the outlet temperature of the compressor 110 drops below the reference temperature C1, the low-speed mode may be canceled, and the dryer 1 may be restored to the initial operation mode before the low-speed mode is executed (S80).

[0144] In addition, if drying of the input laundry is completed, the controller 200 may stop driving the drum 15 and the compressor 110 ( S90 ).

Claims

1. A drying machine, characterized in that: include: The main body is formed with an input port; a drum rotatably mounted on the main body; A driving motor for providing rotational power to the drum; a blower fan forcing air to flow toward the main body; a heat pump system comprising a condenser, an evaporator, and a compressor for heating air supplied to the drum; External air temperature sensor, directly measuring the external temperature; as well as The control unit compares the external temperature with a preset reference temperature to control the plurality of operation modes. When the external temperature is lower than the reference temperature, the control unit determines that the driving environment of the dryer is in a low temperature state and forces the initial acceleration of the compressor to a mode in which the operating frequency of the compressor is the highest.

2. The drying machine according to claim 1, characterized in that The control unit ignores the operation mode input by the user among the plurality of operation modes in the low temperature state.

3. The drying machine according to claim 1, characterized in that When the external temperature is equal to or higher than the reference temperature, the control unit operates in the operation mode input by the user.

4. The drying machine according to claim 1, characterized in that The multiple operating modes include: a speed mode in which the initial drive frequency and the variable minimum frequency of the compressor are the highest; a standard mode, wherein the initial driving frequency and the variable minimum frequency of the compressor are lower than those of the speed mode; and In the energy-saving mode, the initial driving frequency and the variable minimum frequency of the compressor are lower than those in the standard mode.

5. The drying machine according to claim 4, characterized in that: When the external temperature is lower than the reference temperature, the control unit controls the vehicle to operate in the speed mode.

6. The drying machine according to claim 1, characterized in that The control unit checks an outlet temperature of the compressor to determine whether the compressor is in an overload state.

7. The drying machine according to claim 6, characterized in that A compressor outlet side temperature sensor is included for measuring an outlet side temperature of the compressor.

8. The drying machine according to claim 7, characterized in that The control unit compares a preset first reference temperature with the measured outlet temperature of the compressor to determine whether the compressor is overloaded.

9. The drying machine according to claim 8, characterized in that The control unit determines that the compressor is in an overloaded state when the outlet-side temperature of the compressor is equal to or higher than the first reference temperature.

10. The drying machine according to claim 6, characterized in that When the control unit determines that the compressor is in an overloaded state, the control unit controls the compressor to execute a low-speed mode in which the compressor is operated at a variable frequency lower than a variable minimum frequency in the currently executed operation mode.

11. The drying machine according to claim 10, characterized in that The control unit determines the outlet-side temperature of the compressor at a predetermined period in the low-speed mode, and reduces the frequency of the compressor in stages by a set frequency reduction value.

12. The drying machine according to claim 10, characterized in that The control unit compares the outlet temperature of the compressor with a preset second reference temperature to determine whether the temperature inside the drum has reached a temperature suitable for drying.

13. The drying machine according to claim 1, characterized in that It also includes a humidity sensor disposed inside the drum, The control part determines a drying state of the laundry based on humidity information sensed by the humidity sensor.

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