ES2340427T3 - IMPROVEMENTS IN A CLOTHING DRYING MACHINE AND A CORRESPONDING CLOTHING DRYING METHOD. - Google Patents

Abstract

A method is disclosed for drying clothes in a clothes drying machine of the so-called tumbler type provided with a rotating drum, wherein, during the drying cycle, the rotation speed of the drum is variable from a first pre-defined speed value (V1) to a sequence of successive speeds, each one of which has a respective discrete and different value, wherein the values of such successive speeds are progressively decreasing. The first rpm or rotational speed value is adapted to cause the drum to rotate so that the clothes with a high moisture content is adequately tumbled, i.e. lifted and allowed to fall inside the drum, and is thus higher than the rpm or rotational speed value at which the clothes tend to substantially roll up into a clot on the bottom of the drum. During at least one of said successive rotational speeds of the drum, the respective rotational speed undergoes at least one temporary reduction to at least a lower speed value for a respective short period of time.

Description

Improvements in a clothes dryer machine and in a corresponding clothes drying method.

The present invention relates to a method improved clothes drying and an improved clothes drying machine  corresponding, preferably a tumble dryer of the type intended for use in homes, adapted to perform cycles of drying in which the drying process is carried out causing The rotation speed of the drum is adjusted according to a simplified function that takes into account the newly estimated value, but not measured, of the moisture content of the clothes being worn manipulating

The invention can also be applied to machines clothes dryers of both the condenser type and the type of escape, in which adaptations both related to the construction as related to the method, when these are in Particularly necessary for different trend patterns followed by the moisture content of the clothes inside the drum depending on the type of machine involved that must be properly taken into account, they are well within the capabilities of all subject matter experts and therefore easily conceivable, Implementable and verifiable by them.

The fact must first be emphasized here that, when a drying cycle is performed in a dryer machine of clothes, the clothes that are being introduced into the drum have a moisture content that is initially quite high and that then gradually decreases as the clothes dry. This practically means that the overall weight of the load of clothes, that is, the weight of the clothes including the content of residual moisture thereof tends to decrease progressively from A pretty sensitive way.

Therefore, this particular behavior of the load to dry has a marked effect on the alteration of rotational speeds of the drum to a fairly sensitive degree during the drying cycle. In particular, in the initial phases of the drying process the load to dry, because it is soaked of water, that is to say that it has a high moisture content, it is very heavy therefore, when it rises from the bottom of the drum, weighs much larger on clothes lifts provided in the drum, so that said load does last term that slows down the rotation speed of the drum, so that the drum, although it is usually considered as powered by constant speed, it is spun just really so that supplies a constant pair.

Therefore, due to this reduction in actual rotation speed of the drum, the load of clothes inside said drum tends to stop rising following the movement of the drum, while, rather, falls on the bottom of it, in Where it tends to remain.

In these circumstances, the widely known curl effect in which - as is symbolically shown in figure 1 - clothes tend to roll up forming a chipboard. This curl effect - as it is will mention you here in what follows to mean exactly this particular phenomenon - it is widely known to all subject matter experts and therefore does not require any explanation more.

It is in all cases a phenomenon that causes the general capabilities of performing a drying of a tumble dryer suffer very serious inconveniences - and again widely known as such in the art - mainly in terms of a significantly longer drying time, a greater energy consumption and an impediment to smooth progress of own drying process, since - how can it really be appreciated  easily - the clothes located inside the chipboard that is formed of this way on the bottom of the drum is practically not accessible to the flow of hot drying air blown into the drum and through it for that purpose, with the result definitive that - at the conclusion of the drying process - said load of clothes is generally presented as being still compacted with itself or seriously wrinkled and folded and, in any case, showing a completely inadequate uniformity in the effect of dried

This curl effect tends to occur particularly when you are handling loads of clothes that include items as wide as bedclothes, bath towels and similar, where the probability of rolling clothes forming an agglomerate is increased by the large size of the article, which is wrapped around the others, or which include even sheets or other similar pieces of clothing that are sized large enough to spontaneously tend to squirm.

With a view to preventing such an effect from occurring clothing curls have been developed and are being made really drying programs that require you to invest alternatively the direction of rotation of the drum. For other In part, these programs also include phases that require that the heating element used to heat the drying air be disconnected during the short periods of time in which reverses the direction of rotation of the drum, doing so, by of course, the duration of one's own is significantly lengthened drying cycle

In addition, it should be noted that the parties components used to develop such a connection function and disconnection of the heating element are inevitably subject to marked wear very fast due to high rates of power that are being handled and ruled.

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On the other hand, during the final phases of a drying cycle the load of clothes that is drying becomes, of course, much lighter and this makes, reciprocally, that decrease the resistance to lifting your own clothes and, as result, favors a corresponding increase in the speed of drum rotation, given the constancy previously remembered in the torque output of the drive motor. As a result, the Rotation speed of the drum increases correspondingly, and this phenomenon makes the clothes contained in the drum distribute more or less evenly against and along the wall cylindrical drum.

Therefore, if such rotation speed of drum increases to an excessive degree, referred to the humidity level In the end, another particular effect tends to occur - again widely known as such in the art -. Specifically, this effect depends on the fact that the centrifugal force at which the load of clothes is subjected it becomes precisely too much large, so that the half-dried clothes for now, that is, a lot less wet, it tends to be distributed under a force always growing along the cylindrical wall of the drum, "sticking" like that against her.

Such a phenomenon also has an adverse effect, since that the clothes that are being thus distributed, that is, sticking with this way against the peripheral wall of the drum, let practically being reached directly by the air flow hot that is blowing through the drum so that cross the center of it following an axial direction.

With a view to at least partially obviating this unwanted effect, European patent publication EP 1 103 648 B1 describes a clothes dryer machine with a rotating drum intended to contain the clothes you want to dry, where it is given teaching that the drum rotation speed is adjusted continuously to have the drum spinning at a speed that decreases as the drying cycle progresses and, in In particular, it is inversely proportional to the moisture content Instant drying clothes.

However, such a solution is far from being the optimal, since the load of clothes being handled is they can really present humidity conditions that cannot be simply put in no mutual relationship, that is, no keep a clear relationship with the cycle time or, therefore, with the moisture still contained in the clothes on a basis of instant to instant.

As a result, the single progressive reduction and rigidly controlled in the speed of rotation of the drum is far from being effective to ensure that they are actually eliminated automatically and effectively the winding effect mentioned above of clothing during the initial period of the drying cycle and the "stuck" problem during the final period of the same cycle.

JP 05337292 describes a dryer in which, based on output signals from a sensor temperature, a microcomputer performs impulse control by a PWM modulation circuit (width modulation of pulse) and an inverter circuit for a drum motor in order to change drum rotation within a rotation range to high speed decided beforehand until a drying process be advanced to reach the second half of drying.

Therefore, it would be desirable, and constitutes really a main object of the present invention, to provide  a method of drying clothes and a clothes drying machine of the type of turning, that is, using a rotating drum, which is provided with means that are adapted to take due account the actual moisture content in clothing and, therefore, is adapted to work from time to time at a rotation speed  such as the drum as this is necessary with a view to eliminating or less significantly reduce the risk of loading clothes roll up forming a chipboard at the bottom of the drum and - reciprocally - distribute and stick against the wall cylindrical drum, thus avoiding phenomena that would harm Definitely the general performance of the machine.

According to the present invention, these objectives, together with others that will be described later, they are reached in a clothes drying method and a clothes dryer machine corresponding that incorporate the characteristics mentioned in the attached claims, wherein the features and advantages of the present invention will be more readily understood by the description given below by way of non-limiting example with reference to the accompanying drawings, in which:

Figure 1A is a symbolic view showing the improvement, on the situation shown in figure 1 referred to the prior art, in the initial distribution of clothes in the drum of a clothes dryer according to the present invention, obtained with a method of drying clothes according to the present invention;

Figure 2A is a symbolic view showing the improvement, on the situation shown in figure 2 referred to the prior art, in the final distribution of the clothes in the drum of a clothes dryer according to the present invention, obtained with a method of drying clothes according to the present invention;

Figure 3 is a diagrammatic symbolic view of the drum rotation speeds adjusted throughout the drying cycle when using a method of drying clothes according to the present invention;

Figure 4 is a diagrammatic symbolic view of the drum rotation speeds adjusted throughout the drying cycle when using an improved first embodiment of the method of drying clothes according to the present invention;

Figure 5 is an enlarged view of a portion - referred to a limited period of time - from the diagram of the drum rotation speed according to another improved embodiment of the method of drying clothes according to the present invention; Y

Figure 6 is a symbolic representation of a complete drying cycle performed according to the improved embodiment of the drying method of the invention shown in Figure 5.

With particular reference to Figure 3, a clothes drying method according to the present invention is based on the fact that the drum of the clothes dryer machine is induced to rotate at a certain discrete number of rotation speeds different that have to be predefined and that are activated, that is, are adjusted, depending on the particular moment or phase by which The drying cycle is happening every time. Therefore, the value of such predefined rotation speeds of the drum must be selected so as to ensure that - with a high probability with reference to a very common type of load to dry - the clothes are distributed evenly inside the drum because it is turned in such a way that it is prevented from remaining, that is to say roll up and agglomerate, on the bottom of the drum and make it launched by the centrifugal force so that it sticks against the wall cylindrical drum side, thus eliminating uncertainty introduced by, and inherent to, machines and drying methods of prior art clothing exemplified by the publication of European patent cited above No. 1 103 648 B1, as has been explained above.

To eliminate such uncertainty, it is subdivided in this way. the drying cycle in a certain number of subcycles C1, C2, C3 ..., where during each of these subcycles it is adjusted and maintained the speed of rotation of the drum in a respective value constant V_ {c1}, V_ {c2}, V_ {c3} ... that has been predefined and is different for each of said subcycles (figure 3).

All these subcycles are activated in moments predefined throughout the drying cycle and have a duration predefined However, it should be noted especially in this point that these predefined moments throughout a cycle of drying are not necessarily moments that are merely selected or must occur at predefined time intervals one with respect to other, but rather are moments in which some conditions Specified individuals enter into the load to dry, such as described in more detail below.

In addition, in each of these different sayings subcycles the respective drum rotation speed is maintained  at a lower value than the speed used in the subcycle above, so that the effect is also obtained in this case cited above of a drum rotation speed substantially decreasing in some way as the cycle of dried

With the present invention are obtained practically a double result and advantage, that is:

to)

the control means used to adjust and control speed Drum rotation are much simpler and more reliable;

b)

be eliminates uncertainty, which is normally derived from the possibility that the rotation speed of the drum can be inadequate at certain times in view of the actual conditions of the load to dry, that is, for example, may be too much high for a load to dry that is being handled at a higher speed than required or expected (in which case the clothes would tend to stick against the drum wall), or, just like this it can occur during the final stages of the drying cycle, it can decrease inversely to an excessively low value for a load to dry that, on the contrary, is still too wet (in which case the clothes would tend to roll up again forming a agglomerated on the bottom of the drum).

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Although it is true - at least theoretically - that the same can continue to occur in a drying cycle of the type described and disclosed herein, the present invention, not However, it is effective in providing the possibility of avoid such uncertainty by setting these constant values V_ {c1}, V_ {c2}, V_ {c3} ... of the drum rotation speed of such way to ensure that - on a statistical basis - the majority of the loads to dry with a high initial moisture content be turned in all cases, at the beginning of the cycle, at a rotation speed V_ {c1} of the drum that is effective for prevent clothing from agglomerating on the bottom of the drum (it is say, at a sufficiently high rotation speed), such as This is shown schematically in Figure 1A.

In addition, in the final portion of the drying cycle the rotation speed V_ {c3} at which it is induced to rotate the drum during subcycle C3, can be maintained at a value that is low enough to ensure that - when the Most types of loads to dry - clothes that are drying is prevented from sticking against the cylindrical side wall of drum due to centrifugal force, as this is shown schematically in figure 2A.

Figure 3 illustrates, by way of example, the way in which the three subcycles C1, C2, C3, in which it has divided the drying cycle in this case, they are associated with respective rotation speeds V_ {c1}, V_ {c2} and V_ {c3}, where, of course, the actual values of such speeds will be properly adapted and calibrated in each case so that it optimally accommodate the particular machine (diameter of the drum, height and number of clothes lifts in the drum, and similar) in which they are to be implemented, based on exhaustive experiments to be carried out for this purpose, being in fact all subject matter experts fully aware of that for each type of machine, that is, each machine design, the need arises for them to experience, find and implement rotation speeds that finally allow the desired results.

And it is exactly in the course of such experiments where it has been found that, even when the speed of selected rotation for each subcycle really becomes the correct, it is in any case impossible for the clothes to load drying out is completely prevented from adopting a provision substantially stable inside the drum, even though it is not I really hit the drum wall.

Of course, this phenomenon is such that will impair the overall performance of both the dryer machine as of the drying process that is being carried out, since it is generally known that the ideal condition for a process of drying requires constant stirring and stirring of the load at dry and, alternatively, arrange it in front of the direction of flow of the drying air, which moves in a direction from back to front or - although more rarely - in the opposite direction.

Therefore, so that the load to dry an improvement has been experimentally identified advantageous in the way in which the drying method is performed according to the present invention: with reference to figure 4, such improvement resides in making the instantaneous rotation speed of the drum be reduce at predetermined instants and for periods of time T_ {1 (1)}, T_ {1 (2)}, T_ {1 (3)} very short

At the end of each of these short periods of time the drum rotation speed resumes again until the initial value of it or it is decelerated even more for an additional short period of time.

At the end of this short period of time (or periods, depending on the case), the rotation speed of the drum is automatically returned to its initial value.

The favorable effect that is derived in this way lies in the fact that the sudden change in the speed of Rotation of the drum makes the clothes contained inside the drum experience an increased agitation effect, since - if regularly distribute clothes to the cylindrical side wall of the drum (but not sticking against it), just as this has to be thus with the present invention - the sharp deceleration in the rotation speed causes the clothes to fall again temporarily on the bottom or at least towards the center of the drum.

In this case, it is generally known that reinforces, even to a considerable extent, the effect of heat exchange between hot drying air and clothes contained in the load to be dried.

When the drum is restored afterwards carrying it at the initial rotation speed thereof, the load to dry it tends, of course, to reorganize itself by adopting a provision that it is geometrically, but not materially or physically, similar to the original, in the sense that the parties originally more outside of the load to dry now become the most interiors, and vice versa: hence the effect of enhanced agitation noted above.

In addition, it can easily be seen that such effect is amplified even more if they are enabled every time two of such short periods of speed reduction previously indicated one after another and these are made to respective reduced speeds D1 and D2 compared to speed initial precedent constant V1.

Figure 5 provides a simple Schematic and easy to follow representation of this process, in where the way in which during the C1 subcycle is in fact exemplified they are determined, that is, they are made to occur, certain reductions of speed, resulting in reduced speeds they have values of D1 (in relation to the original speed V1) and D2 (in relation to the preceding speed V1-D1), respectively.

At the end of the second step of reducing speed D2 the drum rotation speed resumes - in the instants I_ {1}, I_ {2}, I_ {3}, ... - up to the value original V1 of it.

Of course, this procedure can be carried out. also carried out in the same manner during the other C2 subcycles, C3, etc.

Figure 6 illustrates a simple schematization of such procedure; however, for reasons of more simply, a detailed description of the process involved, since this is totally obvious and obvious to subject matter experts

In this context, it should be noted only that, since the drum is induced to rotate at speeds that are progressively lower, meaning that they decrease in a sequence during the various subcycles C1, C2, C3, even the speeds resulting endings V_ {k1}, V_ {k2}, V_ {k3} of said short films periods of deceleration, that is, of speed reduction, in which reduces the value of the rotation speed of the drum in a defined amount D1 and D2, respectively, with relation to the value of the speed at which it is performed regularly each of such subcycles that include such short periods, will, of course, correspondingly become progressively lower.

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In any case, the present invention provides another advantageous improvement: in fact, the instant selected to start the subcycles earlier mentioned C1, C2, C3 ... within the drying cycle that is being performing can be made independent of the length of the interval of preset time since the beginning of the cycle of drying, as it has been considered to occur up to this point, to do it, instead, depending on the real level of humidity reached in clothes.

To this end, a humidity sensor is connected - of a way widely known as such in the art - to control means used to govern the speed of rotation of the drum and the operation of such means is programmed so that, after activation of the first C1 subcycle, the second C2 subcycle begins only when it has been perceived that a predefined moisture content has been reached in the clothes, in whose moment said predefined moisture content should be, by course, low enough to ensure that the respective speed V_ {c2}, at which it will be rotated now the drum, be effective to allow the clothes in the load to drying is properly distributed in the central region of the drum, that is, without rolling up or crushing again on the bottom of the drum

Of course, you can also follow the same procedure in subsequent phases, that is, subcycles; in other words, when it is perceived that the level of moisture in the clothes has further decreased to another value adequately more low, then the subsequent subcycle C3 starts and the drum is induced to rotate at the respective speed V_ {c3}, and thus successively.

It could easily be objected at this point that the process described above is ultimately quite similar to that described in EP 1 103 648 B1 cited above; however, such objection will appear to be virtually unfounded if it is only considered the pure and simple fact that in the process according to the method of the invention, in all cases the result of fully preventing - or at least quite a degree considerable - that the clothes are rolled up or agglomerated on the bottom of the drum and, on the other hand, be distributed along the wall cylindrical side of the drum and stick against it, as this it is only secured by causing the drum to be induced to rotate at speeds dependent on given humidity levels reached in clothing that, however, is only perceived, evaluated or estimates when you actually go through the subcycles individual.

The substantial difference in respect to to the description of the aforementioned patent resides in the fact that although moisture content is measured in a way continue in such description, automatic control of a speed of rotation that is inversely proportional to the humidity level measured instantaneous does not alone ensure that such speed adjusted is adequate to prevent the clothing contained in the drum is rolled up and agglomerate on the bottom of the drum and also distribute along the wall of said drum and stick against she.

In other words, the fact of associating a inversely proportional way of rotation speed snapshot of the drum to the measured instantaneous moisture content in clothes it is not in itself such as to ensure with total reliability that the load to be dried is handled in an optimal way throughout the drying cycle.

Reciprocally, during a drying cycle performed in accordance with the method of the invention described previously, a kind of "points of Verification "for moisture measurement during the entire  of the same cycle, which allow knowledge to be obtained more precise of the real tendency of the humidity level in function of time and that - based on this - is adjusted from time to time the drum rotation speed more precisely for really optimize the way the cycle is performed dried

Claims (9)

1. Method for drying clothes in a clothes dryer machine of the so-called type of turner provided with a rotating drum, in which the rotation speed of the drum is variable during the drying cycle, said method requiring that the drying cycle be subdivided in a plurality of successive subcycles (C1, C2, C3 ...), where the speed of rotation of the drum in each of these subcycles is adjusted to a respective different and constant value (V_ {c1}, V_ {c2} , V_ {c3} ...) and it is maintained at this value, where the value of the velocity in each of said successive subcycles is lower than the value of the velocity in the preceding subcycle and where for at least one (C1) of said subcycles (C1, C2, C3 ...) the respective drum rotation speed experiences at least a temporary reduction to a lower value (D1) for a respective short period of time (T_ {1 ( 1)}, T_ {1 (2)}, T_ {1 (3)}), characterized in that said reduction periods are expected Temporal velocity ion (D1, D2) occurs in a continuous sequence, that is, one directly after the other, and because, after the last of said periods of speed reduction, the same velocity is resumed up to said constant velocity value initial (V_ {c1}, V_ {c2}, V_ {c3}) corresponding to the respective subcycle of said subcycles (C1, C2, C3 ...). 2. Method according to claim 1, characterized in that the first value (V_ {c1}) of the rotation speed of the drum is a value that is adapted to make said drum rotate so as to ensure that the clothes still very wet are capable of being lifted and falling back into the drum when it passes substantially through the inner central region of the same drum, said value being higher than the value of the speed at which said clothes will tend to substantially roll up forming a chipboard on the bottom of the drum. drum. 3. Method according to claim 1 or 2, characterized in that the rotation speed (V_3) of the drum in the last (C3) of said subcycles (C1, C2, C3 ...) is reduced to a value such that the clothing contained in the drum is prevented from being stably arranged, that is to say that it adheres against the inner peripheral surface of the drum, so that said clothing is capable of being lifted and falling back into the drum as it substantially passes through the inner central region of said drum. Method according to claim 1, characterized in that, after said temporary reduction of the rotation speed to a lower value (D1), the drum is again induced to rotate at the preceding rotation speed. Method according to claim 1, characterized in that said successive rotation speeds (V_ {c1}, V_ {c2}, V_ {c3}) of the drum are activated at predetermined instants during a defined drying cycle. Method according to claim 1 or 5, characterized in that said successive rotation speeds (V_ {c1}, V_ {c2}, V_ {c3} ...) of the drum are activated for periods of time having a predetermined duration. Method according to claim 1 or 5, characterized in that said successive rotation speeds (V_ {c1}, V_ {c2}, V_ {c3} ...) of the drum are activated depending on the actual moisture content in the clothes It is drying up. 8. Clothes dryer machine provided with a rotating drum adapted to contain the clothes to be dried, an air circulation system adapted to circulate a flow of hot air through said drum and control means to control the operation of the various actuator and functional devices, characterized in that it is adapted to operate according to the method according to any one of claims 1 to 6 above. 9. Clothes drying machine according to the preamble of claim 8 and also provided with means adapted to detect the level of moisture still remaining in the clothes, characterized in that it is adapted to operate according to the method according to claim 7.