Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F58/00—Domestic laundry dryers
  • D06F58/32—Control of operations performed in domestic laundry dryers 
  • D06F58/34—Control of operations performed in domestic laundry dryers  characterised by the purpose or target of the control
  • D06F58/50—Responding to irregular working conditions, e.g. malfunctioning of blowers
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
  • D06F2103/28—Air properties
  • D06F2103/30—Pressure
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
  • D06F2103/42—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers related to filters or pumps
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
  • D06F2103/58—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers related to condensation, e.g. condensate water level
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
  • D06F2105/58—Indications or alarms to the control system or to the user
  • D06F2105/60—Audible signals
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
  • D06F2105/62—Stopping or disabling machine operation
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F25/00—Washing machines with receptacles, e.g. perforated, having a rotary movement, e.g. oscillatory movement, the receptacle serving both for washing and for centrifugally separating water from the laundry and having further drying means, e.g. using hot air 
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
  • D06F58/00—Domestic laundry dryers
  • D06F58/20—General details of domestic laundry dryers 
  • D06F58/24—Condensing arrangements

Definitions

• the present invention relates to a method for controlling operating parameters in a clothes dryer or washing/drying machine, as well as to a clothes dryer or washing/drying machine using said method.
• the clothes dryer or washing/drying machine of the present invention is of the condensation type, in accordance with the preamble of the first claim.
• Machines of this kind are per se known and typically comprise a drum containing clothes which are dried by an air flow generated by a fan and heated by an electric resistance.
• the hot air jet flows through the clothes in the drum, thus subtracting moisture from them, and goes through a filter for lint removal and then enters a heat exchanger in which, through the effect of thermal exchange with colder environmental air, it is cooled down and condenses, thereby yielding water that flows into a collecting well located in the lower portion of the machine; from there, the water is conveyed by a pump into a removable tray usually arranged in the upper portion of the machine in a position easily accessible to a user, who can then periodically remove and empty said tray.
• the clothes drying degree in order to avoid unnecessary long drying processes, the well and tray filling levels, in order to avoid any unwanted stopping of the machine, and sometimes also the filter condition.
• a typical example of such clothes dryers is described in European patent EP 481561 to Whirlpool International B.V.; in this case, the clothes drying degree is evaluated by checking the variation of the quantity of extracted water over time; to this end, two different types of solutions may be employed: direct ones, wherein the variation of the quantity of water in the collecting well is measured as the pump is operating (by using a dynamometer, or a capacitor, or a resistor, or a float-type electromechanical system), and indirect ones, which measure the variation of the quantities involved in the pump that conveys the water from the well to the tray (change in the current drawn by the pump, variation of pump rpm, variation of the revolution speed of an impeller in the water duct).
• the pump that drains the well and fills the tray is turned on cyclically at time intervals set by a timer, so that the water quantity variation is measured at predetermined time intervals.
• this solution however involves a certain number of drawbacks: first of all, the pump is turned on regardless of the well filling level; hence the volume of the well must be greater than the maximum volume of the water extracted between two successive pump activations in order to prevent water from overflowing from the well.
• this solution does not allow to evaluate other operating parameters of the machine such as, for example, the cleanliness of the air filter (if present); for this purpose, the user is usually recommended to inspect the filter at predetermined time intervals.
• the present invention aims at solving this and other problems through a method for controlling operating parameters in a clothes dryer or washing/drying machine according to the first claim.
• the idea at the basis of the present invention is to control a certain number of operating parameters of the machine by measuring only one quantity, i.e. by measuring only the pressure of the fluid in the well; to this end, the well is equipped with a pressure sensor which measures any variation of pressure on the well bottom, and hence the level of the fluid in which it is immersed, whether it is water (when there is water in the well) or air (when the well is empty).
• Fig. 1 is a diagrammatic view of a clothes dryer according to the present invention
• Fig. 2 is a general diagram that illustrates the operation of the pressure sensor used in the clothes dryer according to the invention
• Fig. 3 is a sectional view of the condensed water collecting well equipped with the pressure sensor of the clothes dryer of Fig. 1;
• Fig. 4 diagrammatically shows a linear pressure switch included in the aforementioned pressure sensor.
• a condensation-type clothes dryer or washing/drying machine 1 which comprises a frame 2 that houses a drum 3 containing clothes to be dried (not shown); said drum 3 is accessible from the outside through a door
• Drum 3 is supplied with air heated by electric resistance 5 and circulated by fan 6; the air is blown around and through the clothes in drum 3, thus heating them and subtracting moisture therefrom; when exiting drum 3, the damp air goes through filter 7 and reaches exchanger 8, where it condenses; the condensed water is then collected in well 9, while the air flows on to resistance 5 to start a new cycle.
• tray 12 (usually at ambient temperature) conveyed by fan 10.
• the water in well 9 is conveyed by pump 11 into tray 12, where it is collected; tray 12 is a removable one and can therefore be removed to be emptied.
• machine 1 may be equipped with additional components (especially when it is a washing/drying machine), which have been omitted herein for simplicity's sake.
• a pressure sensor 13 which measures the pressure (or pressure variations) of the fluid in the well, whether the latter is empty or full of water.
• sensor 13 is a bell-type sensor, as will be further explained below; it outputs a frequency-modulated voltage signal to a control unit 14 of pump 11.
• Pump 11 is controlled by control unit 14, which is inputted the data detected by pressure sensor 13: when there is no water in the well (or at most only a small quantity of water on the bottom thereof), pump 11 is off and sensor 13, which is not submerged, is subjected to a pressure of approximately 0.1 MPa (atmospheric pressure), referred to as P atm in Fig. 2.
• P atm atmospheric pressure
• the pressure sensor detects pressure values only, and sends them in the form of readable data to control unit 14, which then compares such data with preset threshold values (Pi, P 2 , P 3 , P 4 ) and turns on or off both pump 11 and machine 1 accordingly, as will be described later on.
• preset threshold values Pi, P 2 , P 3 , P 4
• the pressure sensor 13 detects a pressure P atm again, it means that the well has become empty again and that the desired quantity of water has been drained into tray 12; at this point pump 11 is stopped.
• the quantity of water pumped each time into tray 12 is substantially constant, just because the activation of pump 11 is controlled as a function of a threshold pressure value Pi, corresponding to a certain water level in well 9; this did not happen in prior-art machines, wherein the pump was controlled by a timer.
• a threshold pressure value Pi corresponding to a certain water level in well 9
• the speed at which the latter sucks water from well 9 is nonetheless much higher than the speed at which the well is filled; therefore, this may only cause a very small approximation error in the calculation of the quantity of water delivered to the tray.
• Tray 12 has a capacity of about 5 dm 3 ; it follows that several activations of the pump are required (approx. 15 to 25 activations, depending on the quantity of water pumped at each activation) in order to reach the maximum filling condition of tray 12.
• the quantity of water contained in the tray can be known at any time with good approximation by counting the number of times that pump 11 is turned on, since during each activation period substantially the same quantity of water is delivered from well 9 to tray 12, and consequently it is possible to generate an alarm signal when a certain water volume in the tray is reached (corresponding to a certain number of activations of pump 11); to this end, control unit 14 is equipped with a simple counter for counting the number of pump activations; when the tray is removed, the pump activation counter is reset; for this purpose, the machine may for example be provided with a simple switch adapted to notify the control unit that the tray has been removed from the machine frame. Thanks to the large capacity of the tray, the clothes drying cycle normally ends before the tray is completely filled with water, so that the user is only
• the drying cycle may be continued by using the volume of well 9 for collecting the excess water coming from the tray before stopping the drying cycle: to this end, well 9 has a total volume of, for example, approximately 1.5 dm 3 ; when tray 12 is full, the water level in the well rises, until sensor 13 detects a second pressure threshold P 2 in Fig. 2, substantially corresponding to the moment at which well 9 is also full of water; in this condition, therefore, both tray 12 and well 9 are using their maximum capacity; hence, the drying cycle is stopped and the user is warned that it is necessary to empty tray 12.
• the sensor comprises a bell 20 whose open lower edge 21 is close to the bottom of well 9; at its upper end, bell 20 communicates with a linear pressure switch 25 through a tube 22, preferably a hosepipe.
• bell 20 is secured to a horizontal septum 26 which de facto is the cover of the well; this septum is also used as a support for pump 11 that delivers condensed water from well 9 to upper tray 12 of the clothes dryer.
• a closed well 9 like the one shown by way of explanatory but not limiting example in Fig. 3 is employed, the condensate enters well 9 through a hole 77 obtained in one of the well walls (preferably the back wall, i.e. the one facing the rear of machine 1).
• Linear pressure switch 25 is a per se known transducer device which comprises a diaphragm 30 whose deformations, due to pressure variations which will be further discussed below, determine a linear movement of a ferromagnetic element 31 , thereby altering the magnetic field of a coil 32 associated therewith and inducing a corresponding voltage signal.
• Said signal is then processed in a per se known modulated form by an electronic circuit 33 associated with the coil, and is subsequently sent to control unit 14; in Fig. 4, the dashed-dotted line outlines of housing 35 of pressure switch 25, wherein the various aforementioned components are arranged.
• Linear pressure switches like the one described above are commercially available in Italy from ITW Metalflex, Invensys and Bitron; of course, pressure switches of different types may be used as well, so long as that they allow to detect pressure as explained below.
• the water level within bell 20 changes with the water level in well 9 (in Fig. 3 the surface of the water in the bell is indicated through a dashed line); as a consequence, this causes a variation of the pressure of the air contained inside the bell, which is transmitted through tube 22 to linear pressure switch 25.
• control unit 14 detects such pressure variations and sends a corresponding modulated voltage signal of the PWM type (Pulse Width Modulation) to control unit 14, which operates as already explained above. Otherwise, the output signal generated by linear pressure switch 25 and sent to control unit 14 is a frequency-modulated signal, since an oscillator circuit known in the art is associated with linear pressure switch 25.
• PWM Pulse Width Modulation
• filter 7 when filter 7 is clogged there is a pressure drop (below the reference value P atm ) in the air circuit portion downstream of the filter and upstream of fan 6, which is due to the fact that, as fan 6 is sucking air in order to blow it into the drum, a load loss occurs at clogged filter 7; well 9 is located (with reference to the direction of the air flow within the circuit) just downstream of filter 7 and upstream of fan 6, i.e. in the circuit portion where said pressure drop occurs. When it is not submerged (e.g.
• pressure sensor 13 immediately after well 9 has been drained), pressure sensor 13 is subjected to the air pressure at the well itself, and therefore it can detect any pressure drops indicating that the filter has become clogged; it is also possible to generate an alarm, for example, as soon as a third threshold value P 3 (obviously lower than P atm ) of Fig. 2 is reached, in order to warn the user that filter 7 is clogged and should be replaced or cleaned.
• P 3 previously lower than P atm
• pressure value P atm detected in the well may be measured when machine 1 is started for the first time (i.e. when filter 7 is absolutely clean) and then stored, for example, in a non-volatile memory unit included in control unit 14.
• all pressure values detected when pressure sensor 13 is not submerged can be compared with the value stored when the machine was first started, for the purpose of evaluating the filter clogging degree.
• This option is particularly interesting in that it allows to calibrate the filter clogging degree evaluation directly with reference to the specific characteristics of every single machine type: in fact, as can be intuitively understood, (small) pressure drops may be detected in the well area when clothes are loaded into the drum even if the filter is clean, which can thus be taken into account by measuring the air pressure in the well when the machine is started for the first time and by comparing each subsequent reading with that value; moreover, this option simplifies the filter checking operation when the same system is installed in two different machines in which the air circuit has different aerodynamic characteristics, because it allows that same system to automatically learn pressure value P a t m -
• the well pressure measurement may be carried out by using a pressure sensor which provides either an absolute reading (i.e. which detects the absolute well pressure value) or a relative reading (i.e. which detects pressure variations).
• a pressure sensor which provides either an absolute reading (i.e. which detects the absolute well pressure value) or a relative reading (i.e. which detects pressure variations).
• pressure sensor 13 may either be inserted in well 9 or be external thereto and

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Control Of Washing Machine And Dryer (AREA)
• Detail Structures Of Washing Machines And Dryers (AREA)
• Drying Of Solid Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 2008
  • 2008-02-29 IT IT000153A patent/ITTO20080153A1/it unknown
  • 2008-12-23 PL PL08872899T patent/PL2250312T3/pl unknown
  • 2008-12-23 AT AT08872899T patent/ATE542949T1/de active
  • 2008-12-23 ES ES08872899T patent/ES2381322T3/es active Active
  • 2008-12-23 EP EP08872899A patent/EP2250312B1/fr not_active Not-in-force
  • 2008-12-23 WO PCT/IB2008/003617 patent/WO2009106926A1/fr not_active Ceased

Non-Patent Citations (1)

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