AU2011253568A1

AU2011253568A1 - Laundry dryer with environmental temperature sensor

Info

Publication number: AU2011253568A1
Application number: AU2011253568A
Authority: AU
Inventors: Jurgen Kubler; Andre Widmer
Original assignee: V-Zug AG
Current assignee: V-Zug AG
Priority date: 2010-11-22
Filing date: 2011-11-18
Publication date: 2012-06-07
Anticipated expiration: 2031-11-18
Also published as: CN102560990B; PL2333149T3; DK2333149T3; CN102560990A; SI2333149T1; EP2333149B1; EP2333149A1; AU2011253568B2

Abstract

Abstract A temperature sensor (20) is provided in a laundry dryer, by means of which the environmental tem 5 perature can be measured. The environmental temperature can, e.g., be used to better control the cooling of a heat pump (2, 3, 5, 6) of the device, to more accurately estimate the process duration, to more reliably determine a degree of contamination of the fluff filter (12), or to 10 determine various parameters of the drying process. (Fig. 1) Drum Evaporator Condenser - 9 additio 21 nalheat A -0,exchan- - compressor ger * ~ 7/' ' u.................................... .. .......... 22 Tu control unit _______ _ Fig. 1

Description

Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Laundry dryer with environmental temperature sensor The following statement is a full description of this invention, including the best method of performing it known to me/us: P/00/011 Field of the invention 5 The invention relates to a laundry dryer with a drum for receiving the laundry to be dried, with a processing air circuit for drying the laundry in the drum and with a control unit. The invention further relates to a method for operating such a laundry dryer. 10 Background EP 2 006 437 describes a laundry dryer where laundry can be dried in a drum. Processing air is fed 15 through the drum in a processing air circuit. A heat pump is provided for drying and heating the processing air. The device further comprises a cooling fan in order to cool a part of the heat pump with environmental air and thereby to carry off excess heat from the device. The de 20 vice is adapted to operate the cooling fan in a manner dependent from the temperature of the fluid in the heat pump. Summary of the invention 25 It is an object of the invention to provide a device and a method of this type which can be well adapted to the current operating parameters. This object is achieved by the laundry dryer and the method according to the independent claims. 30 Accordingly the control unit of the device is adapted to determine the environmental temperature by means of a temperature sensor and, depending on the envi ronmental temperature, to control the drying process and/or a display of the device. 35 There are various possibilities to implement the invention, some of which are mentioned in the follow ing as well as in the detailed description below. These SU/ig P10611 0AUO0 1 A 11 I 1I 2 various possibilities can be used alternatively or in combination. If the laundry dryer has a heat pump adapted to dry and heat the processing air in the processing air 5 circuit, the knowledge of the environmental temperature can be used for a better control of the heat pump. In particular cooling means can be provided in order to cool at least part of the processing air circuit and/or of the heat pump by means of environmental air, as it is de 10 scribed in EP 2 006 437 or EP 1 156 149. The cooling means can be operated in dependence of the environmental temperature, in particular by operating them in a stronger manner or for longer periods at higher environ mental temperatures than at lower environmental tempera 15 tures. A knowledge of the environmental temperature can also be used for more reliably detecting the contami nation state of the fluff filter of the device. Conven tionally, the process duration of the drying process, 20 e.g. the time required for the water content of the laun dry or the processing air to fall below given threshold, is measured for this purpose: A long process duration is indicative of a higher degree of contamination. However, a long process duration can also be caused by a high en 25 vironmental temperature. Other methods determine the count or frequency of the overheating cycles of the com pressor of the heat pump during a drying process: This count increases when the fluff filter loses permeability. Also in this case, however, the count can increase be 30 cause the environmental temperature is high without that the fluff filter is particularly strongly contaminated. Therefore a measurement of the environmental temperature allows a more reliable detection of fluff filter contami nation in both cases. 35 If the laundry dryer has a display for dis playing the expected process duration of the drying proc ess, a knowledge of the environmental temperature can be SU/ig P10611OAUO0 1411 2011 3 used to more accurately estimate this process duration because the process duration typically increases with in creasing environmental temperature. A knowledge of the environmental temperature 5 can also be useful for other applications, such as for a calculation of an estimated energy consumption, for the determination of an optimum process temperature, or for the determination of the duration of individual process ing steps. 10 Brief description of the drawing Further embodiments, advantages and applica 15 tions of the invention are described in the dependant claims as well as in the following description, which makes reference to the figure. The figure shows a block diagram of the most important components of a laundry dryer. 20 Preferred embodiments Design of the device 25 The device of Fig. 1 comprises a drum 1 for receiving the laundry to be dried. A processing air cir cuit is provided (which is shown in solid lines in Fig. 1), in which heated processing air is fed through drum 1 and a fluff filter 12, whereupon it is cooled down, then 30 again heated up and fed back to drum 1. By cooling the processing air down, the same is dried in known manner. A fan 10 is used for pumping the processing air. Further, a heat pump circuit is provided 35 (with the path of the fluid conveyed by the heat pump circuit being shown in dotted lines in Fig. 1). The fluid is fed by means of a compressor 2 to a condenser 3, from SU/ig P106110AUOO IA 11 )AI 1 4 there to an additional heat exchanger 4, then through an extension valve 5, e.g. a capillary or a proper expansion valve, to an evaporator 6 and finally through an optional heater 9 back to compressor 2. The evaporator is used to 5 cool down the processing air and to dry it, while the condenser 3 is used to heat the processing air back up, such that it can receive new water. As can be seen from Fig. 1, a cooling fan 7 is provided, which serves to cool at least part of the 10 heat pump and/or of the processing air circuit by means of environmental air. In the embodiment shown in Fig. 1 the cooling fan blows environmental air through addi tional heat exchanger 4 in order to cool the same. Cooling fan 7 and additional heat exchanger 4 15 serve to carry off heat from the heat pump circuit and therefore from the whole system and to transfer this heat to the environmental air. Advantageously the amount of the carried off heat is controlled in dependence of the temperature of the heat pump circuit (and/or in depend 20 ence of the temperature in the processing air circuit), e.g. by operating the cooling fan 7 with increasing aver age power when the temperature increases and with de creasing average power when the temperature decreases. This function and operation of the additional heat ex 25 changer are described in detail in EP 1 884 586 and EP 2 006 437. However, as described below, the control of the cooling fan 7 is also dependent on the environmental tem perature. Further the device of Fig. 1 comprises sev 30 eral temperature sensors, such as: - A first temperature sensor 20 measures the environmental temperature Tu of the device. The term "en vironmental temperature" is understood to designate the temperature of the room in which the laundry dryer is lo 35 cated, or a temperature close (e.g. within less than 2 *C) to this room temperature. The purpose and design of the temperature 20 are described in more detail below. SU/ig P10611 0AUO0 1A11 9M11 5 - A second temperature sensor 21 measures the temperature of the fluid in the heat pump between expan sion valve 5 and evaporator 6. - A third temperature 22 measures the tem 5 perature of the fluid of the heat pump between evaporator 6 and compressor 2. In the present context only first temperature sensor 20 is necessary, while the other temperature sen sors are optional. 10 A control unit 8 of the device processes the signals from the different temperature sensors and from any further sensors, and it controls the device dependent on the measured signals and the input from the user. For receiving user input, the device has an operating console 15 15. Further, control unit 8 can operate a display 16, which is e.g. used to display operating parameters and/or an expected process duration of the drying process to the user. 20 Applications of the environmental temperature Tu The device is substantially operated in the manner described in EP 1 884 586 or EP 2 006 437. A knowledge of the temperature Tu, however, allows various 25 improvements, e.g. relating to efficiency, reliability and user information. Some examples are described in the following in more detail. a) Controlling the cooling 30 As mentioned, cooling fan 7 carries off heat from the system by means of environmental air. Its effi ciency depends on the environmental temperature Tu. Therefore control unit 8 advantageously operates cooling fan 7 depending on the environmental temperature Tu, and 35 in particular it operates cooling fan 7 with higher aver age speed and/or in longer periods for a higher environ mental temperature Tul than it does for a lower environ SU/ig P106110AUOO 1A II A11 6 mental temperature Tu2 < Tul. For this purpose it is e.g. possible to modify the table in paragraph 31 of EP 1 884 586 to depend on environmental temperature Tu, by setting the values in the left column of the table to be 1 or 20C 5 lower if the environmental temperature is above 300C. A control scheme of this type can also be used if the cooling fan 7 does not cool the heat pump, but (by means of an air-air-heat exchanger) the air in the processing air circuit directly. 10 In the examples above the cooling means are formed by cooling fan 7, which blows environmental air against a heat exchanger, by means of which the heat pump fluid and/or the processing air can be cooled. In a fur ther embodiment the cooling means can also be formed by a 15 controllable opening in the processing air circuit, which can be partially or fully opened by means of control unit 8 in order to replace part of the processing air in the processing air circuit by environmental air, as it is de scribed in EP 1 156 149. In this manner heat can be car 20 ried off from the system as well. Advantageously the opening is controlled as a function of the environmental temperature Tu in such a manner, that, for a high envi ronmental temperature Tul, a stronger air exchange takes place than for a low environmental temperature Tu2 < Tul. 25 b) Detection of the fluff filter contamina tion A knowledge of the environmental temperature Tu can also be used to detect a contamination of fluff 30 filter 12 in a more reliable manner. It has been known that an increasing contami nation of the fluff filter leads, on the one hand, to a temperature rise in the processing air circuit and in the heat pump and, on the other hand, to an increase of the 35 process duration, i.e. the duration required for reaching a given drying quality. By measuring at least one of these quantities, i.e. (a) a temperature parameter de SUig P10611 0AUO0 1A 11 ')A11 7 pending on the temperature in the processing air circuit or in the heat pump and/or (b) the process duration, the degree of contamination of the fluff filter can be deter mined. However, this temperature parameter as well as 5 this process duration increase also if the environmental temperature Tu increases. Therefore a more accurate esti mate of the degree of contamination of the fluff filter can be obtained by taking the environmental temperature into a count. 10 In other words, the degree of contamination of fluff filter 12 is therefore advantageously determined dependent on (i.e. by using) at least the following pa rameters: - A process duration of the drying process 15 and/or a temperature parameter depending on the tempera ture in the processing air circuit and/or in the heat pump of the laundry dryer, and - The environmental temperature Tu. The process duration is an especially suited 20 parameter if this duration is defined based on the humid ity present in the laundry or the processing air. For this purpose drum 1 can e.g. be provided with suitable sensors for measuring the electrical conductivity of the laundry. 25 The temperature parameter mentioned above can e.g. be the temperature at a location in the processing air circuit or in the heat pump. In a further embodiment of a heat pump laun dry dryer, the temperature parameter can also be the 30 count of overheating cycles of the heat pump of the de vice during a drying process. For this purpose the heat pump is provided with a temperature sensor whose signal is compared to a maximum allowable value. If this maximum allowable value is exceeded, control unit 8 switches off 35 compressor 2 of the heat pump until the temperature value falls below an allowable threshold value (= overheating cycle). Thereafter compressor 2 can be switched on again SU/ig P10611 OAUOO I A I Ifl n1I 8 if required. The number of such overheating cycles in creases with increasing contamination of fluff filter 12, but also with increasing environmental temperature. For example, at an environmental temperature Tu below 25'C a 5 critical contamination of the fluff filter 12 can be de tected if, during a drying process, at least four over heating cycles are detected. At an environmental tempera ture Tu between 25*C and 30*C a critical contamination is detected if at least six overheating cycles occur, at Tu 10 > 30'C at least eight overheating cycles are required. The result of the determination of the fluff filter contamination can, e.g., be displayed on display 16, e.g. as a request to clean fluff filter 12. 15 c) Estimating process duration A knowledge of the environmental temperature Tu can also be used to estimate a probable process dura tion, e.g. in order to display the same on display 16. As it has been mentioned above it is basi 20 cally known to display the expected process duration of a drying process in a laundry dryer. Corresponding methods are known to the skilled person. However, since the proc ess duration increases with increasing environmental tem perature Tu, more accurate predictions can be made by 25 taking the environmental temperature Tu into account when determining the process duration. Therefore, control unit 8 is advantageously designed to calculate the estimated process duration as function of environmental temperature Tu. For this purpose control unit 8 can e.g. comprise a 30 table with correction factors depending on environmental temperature Tu. The conventionally calculated process du ration is to be multiplied with the correction factor at tributed to the current environmental temperature. The correction factors can, e.g., be determined by calibra 35 tion measurements of the device manufacturer. d) Other applications SU/ig P10611OAUOO 1A 11 )A11 9 As already mentioned, a knowledge of the en vironmental temperature Tu can, in addition or alterna tively, be used for other purposes, such as for calculat ing an estimated energy consumption, for determining an 5 optimum process temperature, or for determining a process duration of individual processing steps. For example the environmental temperature Tu can be used in order to decide if and how long the device is to be heated at beginning of a drying process. Such 10 heating can be carried out by means of heater 9. A knowledge of the environmental temperature can also be used to set a final drying degree of the laundry. The term "final drying degree of the laundry" designates the degree of dryness (i.e. a humidity con 15 tent) at which the drying process is stopped. The subjec tive sense of humidity varies as a function of environ mental temperature because a varying amount of humidity condenses on the hands when touching the laundry and a varying degree of humidity (e.g. caused by sweating) is 20 already present. Therefore users feel humidity or dryness differently depending on environmental temperature. For this reason control unit 8 can advantageously be designed to determine the final degree of dryness, at which the process is stopped, as a function of environmental tem 25 perature. Further, a knowledge of the environmental temperature can also be used to set a post-processing du ration. The condensation efficiency of the dryer varies as a function of environmental temperature such that a 30 post-process duration, attributed to each program, may be too long or too short. For this purpose, control unit 8 is advantageously designed to set the post-processing du ration as a function of environmental temperature. The term "post-processing duration" is to be understood as 35 the duration of time during which the laundry is left at rest after the end of a drying program and before the dryer indicates to the use) that the process is finished. SU/ig P10611 OAUOO I A 11 'In II 10 Measurement of the environmental temperature The environmental temperature can be measured 5 by means of a temperature sensor 20 which is in good thermal contact with the environment, e.g. by being mounted in thermal contact with an exterior wall of the dryer. In another embodiment temperature sensor 20 10 can be arranged in an intake-region of cooling fan 7, i.e. in a region where cooling fan 7 sucks in fresh envi ronmental air into the device. Temperature sensor 20 can also be arranged directly on control unit 8, i.e. on a printed circuit 15 board of control unit 8. In a further embodiment temperature sensor 20 can also be arranged at the processing air circuit and/or at the heat pump, and it can, e.g., be formed by one of the temperature sensors 21 or 22. In this case control 20 unit 8 is adapted to measure the environmental tempera ture Tu by means of the temperature sensor in a period where the dryer is at rest, i.e. in an interval between two drying processes. Advantageously the time since the proceeding drying process is sufficiently large (in par 25 ticular at least one hour, e.g. several hours), such that the dryer is in a thermal equilibrium with its environ ment. A measurement is, however, also possible at an ear lier time after a drying process if the environmental temperature is estimated from the current temperature at 30 the temperature sensor as well as from the cooling rate. In such an embodiment it is therefore possi ble to measure with a single temperature sensor (a) the environmental temperature between drying processes and (b) a process temperature during a drying process (e.g. 35 the temperature of the heat pump or of the processing air circuit). SUlig P10611 0AUO0 1A1112111 11 While the above describes advantageous em bodiments of the invention, it is to be clearly under stood that the invention is not limited thereto and can also be carried out in different manner within the scope 5 of the following claims. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. SUig P10611OAUOO 14 11 2011

Claims

1. A laundry dryer comprising a drum (1) for receiving laundry to be dried, 5 a processing air circuit for drying the laun dry in the drum (1), a control unit (8), and a temperature sensor (20) for measuring an environmental temperature, 10 wherein the control unit (8) is adapted to determine the environmental temperature by means of the temperature sensor (20) and to control a drying process and/or a display (16) as a function of the environmental temperature. 15

2. The laundry dryer of claim 1 further com prising a heat pump (2, 3, 5, 6) adapted to dry and heat processing air in the processing air circuit and cooling means for cooling at least part of 20 the processing air circuit and/or of the heat pump (2, 3, 5, 6) by means of environmental air, wherein the control unit (8) is adapted to control the cooling means as a function of the environ mental temperature, and in particular to operate the 25 cooling means in a stronger and/or longer manner at a higher environmental temperature than at a lower environ mental temperature.

3. The laundry dryer of claim 2 wherein the cooling means comprises a cooling fan (7) for cooling at 30 least part of the processing air circuit and/or the heat pump (2, 3, 5, 6) by means of environmental air.

4. The laundry drying of claim 3 further com prising a heat exchanger (4) cooled by said cooling fan (7). 35

5. The laundry dryer of any of the claims 3 or 4 wherein the temperature sensor (20) is arranged in an intake-region of the cooling fan (7). SU/ig P10611 0AUO0 1A 11 'A 11 13

6. The laundry dryer of any of the claims 1 to 4 wherein the temperature sensor (20) is in thermal contact with an exterior wall of the laundry dryer.

7. The laundry dryer of any of the proceeding 5 claims wherein the temperature sensor (20) is arranged at the processing air circuit and/or at a heat pump (2, 3, 5, 6) of the laundry dryer, and wherein the control unit (8) is adapted - to determine the environmental temperature 10 by means of the temperature sensor (20) in an interval between drying processes of the laundry dryer, and - to determine a process temperature by means of the temperature sensor (20) during a drying process. 15

8. The laundry dryer of any of the proceeding claims wherein a fluff filter (12) is arranged in the processing air circuit, wherein the control unit (8) is adapted to determine a degree of contamination of the fluff filter (12) by using at least the following parame 20 ters: - a process duration of the drying process and/or a temperature parameter depending on a temperature in the processing air circuit and/or in a heat pump (2, 3, 5, 6) of the laundry dryer, and 25 - the environmental temperature.

9. The laundry dryer of claim 8 wherein the temperature parameter is a temperature in the processing air circuit and/or in a heat pump (2, 3, 5, 6) of the laundry dryer. 30

10. The laundry dryer of claim 8 wherein the temperature parameter is a count of overheating cycles of a heat pump (2, 3, 5, 6) of the laundry dryer during a drying process.

11. The laundry dryer of any of the proceed 35 ing claims wherein the laundry dryer comprises a display (16) for displaying an expected process duration of the drying process and wherein the control unit (8) is SU/ig P10611OAUOO 1411 011 14 adapted to calculate the expected drying process duration as a function of the environmental temperature.

12. The laundry dryer of any of the proceed ing claims wherein the temperature sensor (20) is ar 5 ranged on the control unit (8).

13. A method for operating a laundry dryer of any of the proceeding claims wherein the environmental temperature of the laundry dryer is measured by means of the temperature sensor (20). 10

14. The method of claim 13 wherein the envi ronmental temperature is measured by means of the tem perature sensor (20) in an interval between two drying processes, and wherein, during a drying process, a proc 15 ess temperature is measured by means of the temperature sensor (20).

15. The method of claim 14, wherein a tem perature of the processing air and/or a temperature in a heat pump (2, 3, 5, 6) of the laundry dryer is measured 20 by means of the temperature sensor (20) during a drying process.

16. The method of any claims 14 or 15 wherein the environmental temperature is measured by means of the temperature sensor (20) when the laundry dryer is in a 25 thermal equilibrium with its environment.

17. The method of any of the claims 13 to 16 wherein a fluff filter (12) is arranged in the processing air circuit, wherein a degree of contamination of the fluff filter (12) is determined by using at least the 30 following parameters: a process duration of the drying process and/or a temperature parameter depending on the tempera ture in the processing air circuit and/or in a heat pump (2, 3, 5, 6) of the laundry dryer, and 35 the environmental temperature.

18. The method of any of the claims 13 to 17 wherein the control unit (8) sets a post-processing dura SU/ig P10611 0AUO0 1A 11 In 1 15 tion and/or a final drying degree of the laundry as a function of the environmental temperature. SU/ig P1061 IOAUOO IA 1 I ')A1 1