Method for operating a laundry dryer equipped with a heat pump system and laundry dryer implementing the method
By combining active and passive switching devices in the heat pump dryer, the problem of prolonged drying cycles caused by overload protection is solved, achieving a more efficient drying process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ELECTROLUX APPLIANCES
- Filing Date
- 2021-05-21
- Publication Date
- 2026-05-12
AI Technical Summary
The overload protection device of existing heat pump dryers causes the cycle time to be extended during the drying cycle, resulting in customer dissatisfaction.
By combining controllable active and passive switching devices, the compressor is temporarily shut down when the drum rotates in reverse, thus avoiding intervention from the overload protection device.
It effectively prevents unnecessary intervention from the overload protection device, reduces the extension time of the drying cycle, and improves user satisfaction.
Smart Images
Figure CN115698417B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of clothes dryers equipped with heat pump systems, and more particularly to a method for operating such machines during a drying cycle. Background Technology
[0002] A clothes dryer (hereinafter simply referred to as a dryer) capable of performing a drying process on clothing typically includes an outer casing housing a treatment chamber (preferably a rotating drum) in which the clothing to be treated is stored. A closed airflow loop performs the drying operation by circulating hot air through the treatment chamber containing the wet clothing.
[0003] This invention can be effectively applied to all machines that perform the drying process on clothes or wet garments, such as laundry washing-drying combination machines. Therefore, in this specification, the term "clothes dryer" will refer to a simple clothes dryer or a laundry washing-drying machine.
[0004] In dryers, heat pump technology is the most energy-efficient way to save energy during the drying process / cycle. In a conventional heat pump dryer, the dry airflow flows in a closed loop. The dry airflow is moved by a fan, passes through a rotating drum, and removes water from the wet clothes. The dry airflow is then cooled and dehumidified in the heat pump system and then heated before finally being sent back into the clothes drum.
[0005] A heat pump system comprises a refrigerant flowing in a closed-loop refrigerant circuit implemented via piping and including a compressor, condenser, expander, and evaporator. The condenser heats dry air, while the evaporator cools and dehumidifies the dry air exiting the drum. The refrigerant flows in the refrigerant circuit, where it is compressed by the compressor, condensed in the condenser, expanded in the expander, and then vaporized in the evaporator.
[0006] Known types of dryers are typically equipped with overload protection devices to prevent damage to the compressor. The overload protection devices typically used in dryers preferably include passive switches that interrupt the power supply from the mains to the heat pump compressor when a predetermined compressor thermal temperature threshold, voltage load, or current absorption threshold is exceeded.
[0007] The passive switch disconnects when the threshold temperature of the heat pump compressor is reached and / or when the current flowing through the passive switch is reached.
[0008] When normal operating conditions are re-established, the passive switch (e.g., a thermal protector) is adapted to return to the operating state that closes the circuit so that electrical power can be supplied to the compressor again.
[0009] However, due to the large inertia of the overload protection device returning to the closed position, there is a considerable delay before the device returns to the operating state, typically about 40 minutes.
[0010] Therefore, the drawback of this known technology stems from the fact that the intervention of the overload protection device increases the duration of the drying cycle and thus leads to customer dissatisfaction.
[0011] The purpose of this disclosure is to overcome at least some of the problems associated with the prior art.
[0012] One object of the present invention is to provide a system suitable for preventing the activation of overload protection devices in a clothes dryer equipped with a heat pump system.
[0013] Another object of the present invention is to realize a system for a clothes dryer equipped with a heat pump system that is suitable for preventing undesirable prolongation of the drying cycle duration. Summary of the Invention
[0014] The applicant has discovered that the shortcomings of known systems can be overcome by providing a clothes processor having a rotating processing chamber, a heat pump system including a compressor, at least one passive switching device adapted to cut off the power supplied to the compressor that is not controlled by a control unit, and by providing a method in which the compressor is temporarily shut down in a timely manner when the rotation of the processing chamber must be reversed.
[0015] According to one aspect of this disclosure, a method for controlling a clothes dryer equipped with a heat pump system as described in claim 1 is provided.
[0016] Further features of the method according to the invention can be found in the dependent claims.
[0017] In another aspect, the present invention relates to a clothes dryer that implements the method according to the invention. Attached Figure Description
[0018] Other features and advantages of the invention will be highlighted in more detail in the following detailed description of preferred embodiments of the invention, provided with reference to the accompanying drawings. In the drawings:
[0019] - Figure 1 An isometric view of a clothes dryer in which the method of the present invention can be implemented is shown;
[0020] - Figure 2 This is for implementing the method of the present invention. Figure 1 A schematic representation of the main components of the machine;
[0021] - Figure 3 This is a simplified flowchart of the basic operation of a method for operating a clothes dryer according to a preferred embodiment of the present invention;
[0022] - Figure 4 This is a simplified flowchart of the basic operation of a method for operating a clothes dryer according to another preferred embodiment of the present invention;
[0023] - Figure 5 This is a simplified flowchart of the basic operation of a method for operating a clothes dryer according to another preferred embodiment of the present invention;
[0024] - Figure 6 This is a schematic representation of the main components of another preferred embodiment of a machine for implementing the method of the present invention;
[0025] - Figure 7 It shows how it changes over time. Figure 6 The refrigerant temperature in the machine's heat pump system. Detailed Implementation
[0026] The invention has proven particularly successful when applied to front-loading dryers with a rotating garment container / drum; however, it is clear that the invention can also be applied to top-loading dryers, and generally to garment dryers in which the garment container can rotate in a first rotational direction and a second rotational direction opposite to the first rotational direction.
[0027] Furthermore, this invention can be effectively applied to all machines that perform the drying process on clothes or wet garments, such as laundry washing and drying combination machines.
[0028] Therefore, the term "clothes dryer" refers to a simple clothes dryer or a clothes washing-drying machine.
[0029] Generally, the clothes dryer or garment dryer according to the invention comprises: a rotating processing chamber into which clothing items can be placed for processing with a dry airflow; a loop in which the dry airflow circulates; a heat pump system including a first heat exchanger for cooling a refrigerant and heating the airflow, an expansion device, and a second heat exchanger for heating the refrigerant; at least one active switching device for selectively activating / deactivating the compressor; and at least one passive switching device adapted to cut off power supplied to the compressor when a predetermined operating parameter threshold is exceeded.
[0030] Figure 1 and Figure 2 A clothes dryer 1 with a heat pump system 50, wherein the method of the invention can be implemented, is shown according to a preferred embodiment of the invention.
[0031] The dryer 1 preferably includes (though not necessarily) an external box-shaped housing 2 that is substantially parallelepiped in shape, which is preferably structured to rest on the floor. A processing chamber 9, preferably composed of a rotatable drum 9, is disposed within the housing 2. A front door 8, pivotally connected to the front upright sidewall 2a, is provided to allow access to the interior area of the drum for placing clothing to be dried therein.
[0032] The roller 9 is advantageously rotated by a roller motor 10 (preferably an electric motor), which preferably transmits rotational motion to the shaft of the roller 9, advantageously via a belt / pulley system (not shown). In different embodiments of the invention, the roller motor may be directly associated with the shaft of the roller 9.
[0033] More preferably, the drum motor 10 allows the drum 9 to rotate in a first rotational direction and a second rotational direction opposite to the first rotational direction.
[0034] The user control interface 15 is preferably located on the top of the housing 2. The user control interface 15 is preferably accessible to the user for selecting drying cycles and inserting other parameters, such as the type of fabric being loaded, dryness level, etc. The user control interface 15 preferably displays machine operating conditions, such as remaining cycle time, alarm signals, etc. For this purpose, the user control interface 15 preferably includes a display 13.
[0035] In different embodiments, such as in a laundry washing and drying combo machine, the user can select and insert other types of parameters, such as washing temperature, washing spin speed, etc.
[0036] In another embodiment, the user control interface can be implemented in different ways, such as being deployed remotely in the case of a remote control system.
[0037] Air inlet path 20 is preferably connected to one side of roller 9, and air outlet path 22 is preferably connected to the other side of roller 9. Air inlet path 20, air outlet path 22, and roller 9 define a drying air circuit 26 for the drying airflow. A circulating fan 28 is typically configured to move the drying air along circuit 26. A dedicated motor 30 preferably operates the circulating fan 28, but in a possible, simpler embodiment, the same motor can operate both the circulating fan 28 and roller 9 (in other words, only one of the two motors 10 and 30 may be present).
[0038] As described above, the dryer 1 then includes a heat pump system 50, which includes a compressor 52, a first heat exchanger 54 (also called a condenser) serving as a hot sink (i.e., a condenser or gas cooler if the refrigerant operates at least at a critical pressure), and a second heat exchanger 56 (also called an evaporator) serving as a cold sink (i.e., an evaporator or gas heater if the refrigerant operates at least at a critical pressure). A throttling valve 58 is typically disposed between the first heat exchanger 54 and the second heat exchanger 56.
[0039] Alternative solutions to throttle valves include expansion devices, capillary tubes, or controlled expansion valves.
[0040] exist Figure 2 In the illustrated embodiment, the dry air circuit 26 forms a substantially closed loop, and the airflow from the drum 9 passes through the second heat exchanger 56 (evaporator) and then through the first heat exchanger 54 (condenser).
[0041] The control unit UC1 is connected to various components of the dryer 1 to ensure its operation. The user control interface 15 preferably communicates with the control unit UC1.
[0042] Electrical power is preferably supplied from the power supply line PM to the dryer 1 via wires connecting L and N (e.g., the live wire L and the neutral wire N connected to the power supply line PM).
[0043] Electrical power is supplied to different components of the dryer 1. Figure 2 In the diagram, only some components of the dryer 1 are explicitly shown as being supplied with electrical power, namely, the control unit UC1 and the compressor 52.
[0044] The compressor 52 is preferably connected in series with the passive switch device 70, and the assembly formed by the compressor 52 and the passive switch device 70 is connected to the live wire L and the neutral wire N of the power supply main line PM.
[0045] The passive switching device 70 is not controlled by the control unit UC1 and is preferably adapted to cut off the power supplied from the main power supply PM when a predetermined operating parameter threshold is exceeded. In a preferred embodiment of the invention, the passive switching device 70 includes a thermal protector adapted to cut off the power supplied from the main power supply PM to the compressor 52 when a predetermined temperature threshold or absorption current threshold is exceeded.
[0046] The active switching device 72, typically a relay or a solid-state device such as a three-terminal bidirectional thyristor switch element, is placed along the neutral line N and can be controlled by the control unit UC1 to enable / disable the compressor 52. In the following text, the active switching device 72 will also be referred to as a "relay," but it should be understood that it can be a different switching device.
[0047] The dryer 1 is also preferably equipped with a first temperature detection device 80 or a temperature sensor for monitoring the operating temperature of the dryer and / or the heat pump. Preferably, the first temperature sensor 80 monitors the operating temperature at the heat pump system 50. More preferably, the first temperature sensor 80 is placed at a predetermined location along the pump system 50 to measure the refrigerant temperature To. The first temperature sensor 80 transmits the information to the control unit UC1. In particular, the first temperature sensor 80 is an NTC thermistor placed in such a way as to measure the refrigerant temperature To at the outlet of the condenser 54 (or the inlet of the expansion valve 58). Alternatively or additionally, one or more temperature sensors may be arranged at different locations in the heat pump system 50, for example, at the outlet of the compressor 52 or more preferably directly on the compressor 52.
[0048] In another preferred embodiment of the invention, the operating temperature of the heat pump system 50 may correspond to any temperature or combination of temperatures detected by any temperature sensor placed at different locations in the heat pump system (e.g., at the outlet of the compressor or directly on the compressor).
[0049] More typically, the dryer 1 may preferably be equipped with a temperature detection device or temperature sensor to detect operating temperatures other than the operating temperature of the heat pump system 50.
[0050] Preferably, the dryer 1 may be equipped with a temperature sensor placed inside the machine's housing to detect the machine's operating temperature, such as a temperature sensor mounted on an electronic board. Alternatively, the dryer 1 may be equipped with a temperature sensor to detect the ambient temperature and / or a drying airflow temperature sensor.
[0051] The dryer 1 implementing the method according to the preferred embodiment of the present disclosure is preferably controlled by a control unit UC1, which receives information and outputs control signals to the components of the dryer 1.
[0052] As mentioned above, the thermal protector disconnection or shut-off event is an event that should be avoided during normal operation of the dryer 1.
[0053] The applicant has recognized that the disconnection of the thermal protector device 70 may be affected by the peak current absorbed by the compressor 52.
[0054] In particular, the applicant has recognized that the peak of the current absorbed by the compressor 52 that could cause the thermal protector device 70 to disconnect occurs during the reverse rotation of the execution drum 9.
[0055] As is known, the drying cycle preferably includes a continuous phase in which the drum 9 rotates alternately in a first rotational direction R1 (e.g., clockwise) and a second rotational direction R2 (e.g., counterclockwise).
[0056] In a preferred embodiment, the roller 9 rotates alternately in a first rotation direction R1 and a second rotation direction R2 to prevent the garment from wrinkling.
[0057] More preferably, the drum 9 rotates primarily in the first rotation direction R1 during the drying cycle, while periodically rotating in the second rotation direction R2 for a shorter period of time. For example, the drum 9 may rotate in the first rotation direction R1 at predetermined main regular intervals, which may last for 4 to 5 minutes, and periodically rotate in the second rotation direction R2 or the reverse rotation direction for 20 to 30 seconds.
[0058] During the reversal of the rotation direction of drum 9, the mass flow rate of dry air generated by circulating fan 28 along loop 26 decreases rapidly. This results in reduced heat exchange between evaporator 56 and condenser 54, and consequently, a decrease in refrigerant pressure at the evaporator outlet. To re-establish the correct refrigerant pressure in the heat pump system, compressor 52 rapidly increases its operation and thus draws in a high current (current peak).
[0059] Therefore, according to one aspect of the invention, when it is determined that a reversal of the rotation of the drum 9 must be performed, an appropriate action is taken. Preferably, as better described below, the action includes shutting off the compressor 52. More preferably, the action of shutting off the compressor 52 is performed before or simultaneously with the reversal of the rotation direction.
[0060] Figure 3 A schematic flowchart illustrating a method for operating a clothes dryer 1 according to a first preferred embodiment of the present invention is shown.
[0061] First, place the clothes to be dried inside the drum 9 (step 100).
[0062] By operating on the interface unit 15, the user selects and starts the desired type of drying cycle / program (step 110), which is preferably based on the fabric type of the garment to be dried.
[0063] Clearly, users can select their desired drying cycle before placing clothes inside the drum 9.
[0064] In the next step (step 120), the heat pump system 50 is activated by turning on the compressor 52. Simultaneously, the circulating fan 28 is preferably turned on. This generates a dry airflow and circulates it through the dry air circuit 26, initiating the drying of clothes within the drum 9.
[0065] As a next step (step 130), the method provides to rotate the roller 9 in a first rotational direction R1 (e.g., clockwise).
[0066] In the next step (step 140), it is evaluated whether the rotation of the roller 9 must be reversed, that is, the roller 9 must rotate in a second rotation direction R2 (e.g., counterclockwise or reverse rotation direction) opposite to the first rotation direction R1.
[0067] In a preferred embodiment of the invention, the evaluation of the rotational reversal is essentially performed by the control unit UC1, since the exact timing of the reversal is scheduled according to the type of drying cycle previously selected by the user. The exact timing of the reversal is preferably stored in the control unit UC1.
[0068] In another preferred embodiment, the step of evaluating whether inversion must be performed (step 140) can be performed in a different manner.
[0069] In another preferred embodiment, the exact time of reversal is not predetermined, but is determined in real time during the drying cycle based on specific events affecting the operating conditions of the clothes dryer and / or heat pump system that require a reversal of the rotation direction of the processing chamber.
[0070] For example, when the load is unbalanced, it may be necessary to reverse the rotation of roller 9. Preferably, the imbalance can be detected by a dedicated sensor or by analyzing the current absorbed by roller motor 10.
[0071] In another embodiment, the rotation reversal can be determined in real time based on the humidity inside the clothing and / or the drum 9, preferably detected by a humidity sensor arranged inside the drum 9 or along the drying air circuit 26. For example, the rotation reversal can be performed when the humidity inside the clothing and / or the drum 9 reaches a predetermined value.
[0072] In another preferred embodiment, the reversal time of the drum 9 can be determined by one or more other specific events. For example, the reversal of the rotation of the drum 9 may occur due to the necessity of reversing the rotation direction of the circulating fan 28. This is particularly relevant to dryers in which the circulating fan 28 and the drum 9 are operated by the same common motor.
[0073] In fact, in some cases, it may be necessary to reverse the flow of the drying air during the drying cycle, such as when the drying efficiency suddenly decreases. Therefore, the flow is reversed by reversing the rotation of the circulating fan 28. Since the motor of the circulating fan 28 is the same as that of the drum 9, the rotation of the drum 9 is also reversed.
[0074] In the next step of the method (step 150), it is assessed whether there are any risk conditions for compressor 52.
[0075] In the following text, the term "risky condition" refers to operating conditions that could lead to the activation of the passive switching device 70 of the compressor 52. In a preferred embodiment of the invention, as better described later, a risky condition refers to conditions indicating that the drying cycle 1 is in a later stage and / or the heat pump system 50 is reaching a critical operating point.
[0076] If no risk conditions are found in the assessment (the output of step 150 is "No"), then the rotation direction is reversed (step 190).
[0077] Conversely, if a risky condition is assessed (the output of step 150 is "yes"), the method provides to shut off compressor 52 (step 160), reverse the rotation direction of roller 9 (step 170), and turn on compressor 52 (step 180).
[0078] In a preferred embodiment, the step of shutting off the compressor 52 (step 160) is performed before the reversal of the rotation direction (step 170), for example, one second before that.
[0079] In another preferred embodiment, the steps of shutting off compressor 52 (step 160) and reversing the rotation direction (step 170) are performed simultaneously.
[0080] The step of turning on the compressor 52 (step 180) is preferably performed after the reversal of the rotation direction (step 170) has been completed. Preferably, the time during which the compressor 52 is stopped (i.e., the time between the step of turning off the compressor 52 (step 160) and the step of turning on the compressor 52 (step 180)) is several minutes (e.g., 2-3 minutes).
[0081] In another preferred embodiment, the step of turning on the compressor 52 (step 180) is preferably performed after the reversal of the rotation direction (step 170) has begun but before its end.
[0082] In fact, it is quite obvious that reversing the rotation direction of roller 9 requires first slowing roller 9 to a stop, then starting the reversal of the rotation direction from zero speed, and then accelerating roller 9 to the desired rotation speed (the end of the rotation reversal).
[0083] Advantageously, the compressor 52 is shut off when the rotation direction of the drum 9 is reversed (step 170). This avoids the compressor 52 absorbing high current (current peak) during the reversal of rotation direction and also avoids the undesirable tripping of the thermal protector of the passive switching device 70.
[0084] Based on the above and as follows Figure 3 In a preferred embodiment of the method shown, the step of shutting off the compressor 52 (step 160) is performed before or simultaneously with the reversal of the rotation direction (step 170), and the step of turning on the compressor 52 (step 180) is performed after the reversal of the rotation direction (step 170).
[0085] Figure 4 A flowchart illustrating a second embodiment of the method is provided. In this flowchart, [the following is an example of a process described in the original text]. Figure 3 The steps corresponding to the steps in the first preferred embodiment shown are identified by the same numbers.
[0086] The difference between this embodiment and the previous embodiment is that the step of shutting off the compressor 52 (step 160) is performed after the step of reversing the rotation direction of the processing chamber 9 (step 170) has begun, and the step of turning on the compressor 52 (step 180) is performed after the step of shutting off the compressor 52 (step 160).
[0087] In a preferred embodiment, the step of shutting off the compressor 52 (step 160) is performed after the rotation direction reversal (step 170) has been completed.
[0088] Preferably, the step of shutting off the compressor 52 (step 160) is performed within a first delay time DT1 after the reversal of the rotation direction of the processing chamber 9 (step 170) has ended. In this case, the first delay time DT1 is preferably up to a plurality of seconds.
[0089] In another preferred embodiment, the step of shutting off compressor 52 (step 160) is performed after the reversal of the rotation direction (step 170) has begun but before it has ended. In this case, the first delay time DT1 is preferably up to a plurality of seconds, more preferably 3 seconds, which is the time typically required to perform the reversal of the rotation direction.
[0090] Figure 5 A flowchart illustrating a third embodiment of the method is provided. In this flowchart, [the following is an example of a process described in the original text]. Figure 3 The steps corresponding to the steps in the first preferred embodiment shown are identified by the same numbers.
[0091] This embodiment differs from previous references. Figure 3The difference in the described embodiment is that the step of reversing the rotation direction of the processing chamber 9 (step 170) is performed after the step of turning on the compressor 52 (step 180).
[0092] The step of shutting off compressor 52 (step 160) is obviously still performed before the step of turning on compressor 52 (step 180).
[0093] Preferably, the step of reversing the rotation direction of the processing chamber 9 (step 170) is performed within a second delay time DT2 after the step of turning on the compressor 52 (step 180). More preferably, the second delay time DT2 is up to a plurality of seconds.
[0094] In another preferred embodiment, the second delay time DT2 is set to be at most 10% of the time during which the intermediate processing chamber 9 rotates in the reverse rotation direction R2. For example, when the intermediate processing chamber 9 rotates in the reverse rotation direction R2 for 25 seconds, the second delay time DT2 can last for 2.5 seconds.
[0095] Regardless of the embodiments considered and described, the first risk condition according to the invention is preferably a condition in which the operating temperature To of the dryer 1 is higher than a first threshold operating temperature T1. The operating temperature To is preferably the operating temperature associated with the heat pump system 50. In this case, a high value of the operating temperature To indicates that the heat pump system 50 has reached its critical operating point.
[0096] In a more preferred embodiment of the invention, the operating temperature To corresponds to the refrigerant temperature (which is preferably detected by the first temperature sensor 80), and the first threshold temperature corresponds to the first refrigerant threshold temperature T1 (e.g., 80°).
[0097] However, in another preferred embodiment of the invention, the operating temperature may correspond to any operating temperature as defined above, such as the machine temperature detected by a sensor placed inside the machine housing, the machine temperature detected by a sensor mounted on an electronic board, the temperature detected by the ambient temperature, or the temperature of the dry airflow.
[0098] The second risk condition according to the invention is based on the length of time the dryer 1 operates.
[0099] Preferably, the second risk condition is used to assess whether the time elapsed since the start of the drying cycle or the working time is higher than the first time threshold t1.
[0100] In fact, a high operating time indicates that drying cycle 1 is in its later stages, such as between the middle and end of the drying cycle, or in other words, the first part of the drying process has passed. It is well known that at the beginning of a drying cycle, clothing is wet and typically not warm. Therefore, in this situation, the heat pump system 50 (especially the refrigerant temperature To) typically operates at a low temperature and is thus in a favorable condition. Conversely, between the middle and end of the drying cycle, clothing is drier and warmer than at the beginning of the cycle, and therefore, the heat pump system 50 (especially the refrigerant temperature To) typically operates at a higher temperature and is thus potentially close to its critical operating point.
[0101] Therefore, the second risk condition indicates that dryer 1 is moving toward the critical operating point.
[0102] The first time threshold t1 preferably depends on the type of drying cycle selected by the user. For example, the first time threshold t1 may be 1 hour for a wool drying cycle and 2 hours for a cotton drying cycle.
[0103] The third risk condition according to the invention is preferably a condition in which the humidity M (which is preferably detected by a humidity sensor) inside the garment or roller 9 is lower than the humidity threshold M1.
[0104] In fact, a low humidity value indicates that the drying cycle 1 is in its later stages, such as between the middle and end of the drying cycle, or in other words, the first part of the drying process has passed. It is well known that at the beginning of the drying cycle, the clothes are very damp, and therefore the humidity inside the clothes or drum 9 is high, i.e., above a given humidity threshold M1. Therefore, the heat pump system 50 (particularly the refrigerant and compressor 52) operates under safe conditions at its safe operating temperature. Conversely, in the later stages of the drying cycle, the clothes are dry or almost dry, the humidity inside the clothes or drum 9 is low, i.e., below the given humidity threshold M1, and therefore the heat pump system 50 (particularly the refrigerant and compressor 52) approaches its critical operating temperature.
[0105] Therefore, the third risk condition indicates that the heat pump system 50 is moving toward the critical operating point.
[0106] In a preferred embodiment of the invention, if only one risky condition has been assessed, for example, if the refrigerant temperature To is higher than the first threshold temperature T1, or if the time elapsed since the start of the drying cycle is higher than the first time threshold t1, or if the humidity M inside the garment or drum 9 is lower than the first humidity threshold M1, then the step of shutting off the compressor 52 (step 160) and the step of reversing the rotation direction of the drum 9 (step 170) are performed.
[0107] In another preferred embodiment of the invention, if a combination of two or more risk conditions has been assessed, the step of shutting off the compressor 52 (step 160) and the step of reversing the rotation of the drum 9 (step 170) are performed.
[0108] Therefore, as can be seen from the above, by temporarily shutting down the compressor 52 when it is necessary to reverse the rotation direction of the drum 9 (step 170) and assess one or more risk conditions, the activation of the overload protection device 70 can be prevented.
[0109] Advantageously, it can prevent shut-off events (i.e., disconnection of the thermal protector device 70), which would mean the shutdown of the compressor 52 and the suspension of the drying cycle, lasting for a relatively long time, typically about 40 minutes.
[0110] According to the present invention, the downtime of compressor 52 (i.e., the time between shutdown (step 160) and turn-on (step 180)) is a short time (several minutes, for example 2-3 minutes), thus significantly reducing the downtime of the drying cycle compared to the downtime caused by the intervention of thermal protector device 70 to shut down compressor 52.
[0111] Figure 6 A schematic diagram of a dryer 201 according to another embodiment of the invention, in which the method of the invention can be implemented, is shown.
[0112] The clothes dryer 201 according to this embodiment includes reference to... Figure 2 The described dryer 1 has the same components, except that it further preferably includes a cooling fan 60 (as described better later) configured as a cooling compressor 52, and a dedicated motor 62 for operating the cooling fan 60. A control unit UC1 is then preferably connected to the motor 62 for controlling it. Corresponding features and / or components in both embodiments are identified by the same reference numerals.
[0113] According to another aspect of the invention, in addition to the aforementioned control related to rotational reversal, other corrective actions are taken to prevent the overload protection device 70 from being activated while the dryer 201 is operating (i.e., after the drying cycle has begun).
[0114] The first preferred correction action provides selective operation of the cooling fan 60 to cool the compressor 52.
[0115] The first correction action is preferably performed under the control of the control unit UC1 based on the detected operating temperature.
[0116] Preferably, if the detected operating temperature, preferably the refrigerant temperature To detected by the first temperature sensor 80, is higher than a given threshold temperature Fan_Ton (hereinafter referred to as the "on threshold temperature"), then the cooling fan 60 is turned on. If the detected operating temperature, preferably the refrigerant temperature To detected by the first temperature sensor 80, is lower than a given threshold temperature Fan_Toff (hereinafter referred to as the "off threshold temperature"), then the cooling fan 60 is turned off.
[0117] Activating the cooling fan 60 helps reduce the compressor temperature, and in turn helps reduce the refrigerant temperature To.
[0118] Conversely, when the cooling fan 60 is deactivated, the compressor temperature and refrigerant temperature To rise.
[0119] Figure 7 An exemplary schematic diagram of the refrigerant temperature To over time is shown, wherein the refrigerant on-threshold temperature Fan_Ton when the cooling fan 60 is turned on is set to 80°C, and the refrigerant off-threshold temperature Fan_Toff when the cooling fan 60 is turned off is set to 78°C.
[0120] It is understandable that the refrigerant temperature To decreases and increases between the two threshold temperatures Fan_Ton and Fan_Toff depending on the corresponding activation and deactivation of the cooling fan 60.
[0121] Therefore, advantageously, the control unit UC1 selectively switches the cooling fan 60 on and off in a timely manner based on the detected operating temperature, so that the compressor 52 is cooled without reaching the critical operating conditions that could cause the thermal protector device 70 to disconnect undesirably.
[0122] The second preferred correction action provides to shut down compressor 52, preferably via relay 72. Compressor 52 is shut down if the operating temperature, preferably the refrigerant temperature To detected by the first temperature sensor 80, is higher than or equal to a given threshold temperature Comp_Ton / off (hereinafter referred to as the "on / off threshold temperature"). For example, compressor 52 is shut down if the refrigerant temperature To detected by the first temperature sensor 80 is higher than or equal to 90°C.
[0123] The shutdown of compressor 52 causes the compressor temperature to drop, which in turn causes the refrigerant temperature To to drop.
[0124] When compressor 52 is off, preferably, a predetermined time period is set before compressor 52 can be turned on again. This time period allows the correct pressure of the refrigerant in pump system 50 to be re-established. The predetermined time period is preferably set to 2-3 minutes. In another preferred embodiment, compressor 52 can only be turned on again when the refrigerant temperature To has dropped below a predetermined temperature.
[0125] Therefore, advantageously, the control unit UC1 shuts down the compressor 52 in a timely manner based on the detected operating temperature, so that the compressor 52 is cooled and does not reach the critical operating conditions that could cause the thermal protector device 70 to disconnect undesirably.
[0126] Advantageously, the corrective action can prevent a shut-off event (i.e., disconnection of the thermal protector device 70) from occurring, which would mean the shutdown of the compressor 52 and the suspension of the drying cycle, lasting for a long time, typically about 40 minutes.
[0127] By correcting the action, in the worst case, compressor 52 is shut down for 2-3 minutes, thus significantly reducing the downtime of the drying cycle compared to the downtime caused by the intervention of thermal protector device 70 to shut down compressor 52.
[0128] In a preferred embodiment of the method, the correction action can be performed from the beginning of the drying cycle.
[0129] In a more preferred embodiment of the method, a correction action can be performed based on one or more events.
[0130] For example, in a first preferred embodiment of the invention, the correction action is performed after a certain period of time has elapsed since the start of the drying cycle (e.g., 30 minutes after the start of the drying cycle). Clearly, this time period can depend on the type of cycle selected, and may be proportional to the duration of the selected cycle.
[0131] In another preferred embodiment of the invention, for example, the correction action is performed when a predetermined humidity is reached inside the drum 9.
[0132] Advantageously, as has been shown from the above description, unwanted shutdown events can be prevented by selectively shutting off the compressor.
[0133] Although illustrative embodiments of the invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those specific embodiments, and that various other changes and modifications can be made to the above embodiments by those skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.
Claims
1. A method for controlling a clothes dryer (1; 201) equipped with a heat pump system (50) during a drying cycle, the clothes dryer (1; 201) comprising: - Control unit (UC1); - Processing chamber (9), in which clothing can be placed for drying with a stream of dry air, the processing chamber (9) being adapted to rotate; - A heat pump system (50) including a compressor (52), a first heat exchanger (54) for cooling the refrigerant and heating the airflow, an expansion device (58) and a second heat exchanger (56) for heating the refrigerant. - At least one passive switching device (70), which is independent of the control unit (UC1) and is adapted to cut off the power supplied to the compressor (52) when one or more predetermined operating parameter thresholds are exceeded; - At least one active switching device (72), which is controllable by the control unit (UC1) for selectively turning the compressor (52) on and off. The method is characterized in that it includes the following steps: - Start the drying cycle; - The heat pump system (50) is activated by turning on the compressor (52); - Rotate the processing chamber (9); - Assess whether it is necessary to reverse the rotation direction of the processing chamber (9), and if it is necessary to reverse the rotation direction, assess whether there are operating conditions of the compressor (52) that could lead to the activation of the passive switching device (70); - If the operating conditions do not exist, the rotation direction of the processing chamber (9) is reversed; otherwise, if the operating conditions exist, the following steps are performed: a) Turn off the compressor (52); b) Reverse the rotation direction of the processing chamber (9); c) Turn on the compressor (52).
2. The method according to claim 1, characterized in that, The step of assessing whether there are operating conditions of the compressor (52) that could lead to the activation of the passive switching device (70) includes assessing one or a combination of the following conditions: - Whether the operating temperature (To) of the clothes dryer (1; 201) is higher than the first threshold operating temperature (T1), wherein the operating temperature (To) of the clothes dryer (1; 201) is detected by at least one temperature sensor (80); - Whether the time elapsed since the start of the drying cycle is higher than the first time threshold (t1); - Whether the humidity (M) inside the garment or the processing room (9) is lower than a first threshold (M1), wherein the humidity (M) is detected by at least one humidity sensor.
3. The method according to claim 2, characterized in that, The operating temperature (To) of the clothes dryer (1; 201) is the refrigerant temperature (To), and the first threshold operating temperature (T1) is the first refrigerant threshold temperature.
4. The method according to claim 2, characterized in that, The operating temperature (To) of the clothes dryer (1; 201) is the operating temperature of the heat pump system (50) and / or the ambient temperature and / or the temperature of the drying airflow.
5. The method according to any one of claims 2 to 4, characterized in that, The value of the first time threshold (t1) depends on the type of drying cycle selected by the user.
6. The method according to any one of claims 1 to 4, characterized in that, The step of assessing whether the rotation direction of the processing chamber (9) must be reversed includes a step of considering the scheduled time for reversing the rotation direction of the processing chamber (9) based on the type of drying cycle selected by the user.
7. The method according to any one of claims 1 to 4, characterized in that, The step of assessing whether the rotation direction of the processing chamber (9) must be reversed includes determining the presence of one or a combination of the following conditions of the clothes dryer (1; 201) requiring the rotation direction of the processing chamber (9) to be reversed during the drying cycle: load imbalance; the humidity (M) of the clothes reaches a predetermined value; the humidity (M) inside the processing chamber (9) reaches a predetermined value; the rotation direction of the drying air circulation fan (28) is reversed.
8. The method according to any one of claims 1 to 4, characterized in that, Step a) of shutting off the compressor (52) is performed before or simultaneously with step b) of reversing the rotation direction of the processing chamber (9), and step c) of turning on the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9).
9. The method according to claim 8, characterized in that, Step c) of turning on the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9) has begun.
10. The method according to claim 8, characterized in that, Step c) of turning on the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9) is completed.
11. The method according to any one of claims 1 to 4, characterized in that, Step a) of shutting off the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9), and step c) of turning on the compressor (52) is performed after step a) of shutting off the compressor (52).
12. The method according to claim 11, characterized in that, Step a) of shutting off the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9) begins.
13. The method according to claim 11, characterized in that, Step a) of shutting off the compressor (52) is performed after step b) of reversing the rotation direction of the processing chamber (9) is completed.
14. The method according to claim 11, characterized in that, The step a) of shutting off the compressor (52) is performed within a first delay time (DT1) after the step b) of reversing the rotation direction of the processing chamber (9) has started or ended.
15. The method according to any one of claims 1 to 4, characterized in that, Step b) of reversing the rotation direction of the processing chamber (9) is performed after step c) of turning on the compressor (52), and step a) of turning off the compressor (52) is performed before step c) of turning on the compressor (52).
16. The method according to claim 15, characterized in that, Step b) of reversing the rotation direction of the processing chamber (9) is performed within a second delay time (DT2) after step c) of turning on the compressor (52).
17. The method according to claim 1 or claim 2, characterized in that, The clothes dryer (201) includes at least one compressor cooling fan (60), and the method includes the following steps: d) Detect the operating temperature (To) of the clothes dryer (1; 201); e) If the operating temperature (To) of the detected clothes dryer (1; 201) is higher than the turn-on threshold temperature (Fan_Ton), then the cooling fan (60) is turned on. f) If the detected operating temperature (To) of the clothes dryer (1; 201) is lower than the shutdown threshold temperature (Fan_Toff), then the cooling fan (60) is turned off.
18. A clothes dryer (1; 201) equipped with a heat pump system (50), said clothes dryer (1; 201) comprising: - Control unit (UC1); - Processing chamber (9), in which clothing can be placed for drying with a stream of dry air, the processing chamber (9) being adapted to rotate; - A heat pump system (50) including a compressor (52), a first heat exchanger (54) for cooling the refrigerant and heating the airflow, an expansion device (58) and a second heat exchanger (56) for heating the refrigerant. - At least one passive switching device (70), which is independent of the control unit (UC1) and is adapted to cut off the power supplied to the compressor (52) when one or more predetermined operating parameter thresholds are exceeded; - At least one active switching device (72), which is controllable by the control unit (UC1) for selectively turning the compressor (52) on and off. The control unit (UC1) is characterized in that it is configured to control the rotation of the compressor (52) and the processing chamber (9) according to the method of any one of claims 1 to 17.
19. The clothes dryer (1; 201) according to claim 18, characterized in that, The clothes dryer further includes at least one temperature sensor (80) and / or at least one humidity sensor.