Patent Description:
Traditional laundry treating appliances, for example washing machines, washer-driers, tumble driers, typically comprise a cabinet containing a rotatable drum wherein the laundry to be treated (i.e. washed and/or dried) can be loaded.

An operating fluid (e.g., depending on the kind of laundry treating appliance and on the treating process to be applied, water, water mixed with a washing/rinsing additive, air), is circulated through the drum by a circulating system (comprising, for example pumps, valves, fans, etc., depending on the kind of fluid to be circulated).

In some known laundry treating appliances, the operating fluid is heated and/or cooled/dehumidified by a heat pump system, typically comprising a compressor, an expansion valve, two heat exchangers (one operating as a condenser, and the other as an evaporator), and conduits fluidly connecting such elements in a closed circuit.

A heat pump system has an improved energy efficiency with respect to traditional heating systems using an electrical heater as heat source.

Some refrigerant flows through the compressor, the condenser, the expansion valve and the evaporator, and through the conduits connecting these to one another.

The refrigerant releases heat to the operating fluid by means of the condenser, and extracts heat and humidity from the operating fluid by means of the evaporator. The compressor converts electromechanical power to thermal power by compressing the refrigerant in the refrigerant circuit Currently, the refrigerants mainly used in heat pump systems of known laundry treating appliances are hydrofluorocarbon (HFC) refrigerants, in particular the ones known as R134a and R407C. Unfortunately, these refrigerants have a high Global Warming Potential (GWP), so alternative refrigerants start to be more and more used in different industries.

Possible alternative refrigerants used for replacing hydrofluorocarbon (HFC) refrigerants in heat pump systems of laundry treating appliances are hydrocarbons refrigerants, such as propane (R290) and propylene (R1270).

These alternative refrigerants have a negligible impact on GWP and their thermo-physical properties makes them very suitable for the typical working conditions of heat pump systems of laundry treating appliances, in particular tumble driers and washer-driers.

The downside of these alternative refrigerants is that they are flammable, and therefore, for limiting possible risks, regulations (e.g. the IEC <NUM>-<NUM>-<NUM> standard) limit the amount of refrigerant that can be charged in the heat pump system to <NUM> (grams).

Inside the heat pump system, when the compressor is switched ON, most of the refrigerant can be found inside the condenser, since in this heat exchanger the refrigerant is at high pressure and, for a portion thereof, in liquid state, so with a very high density.

The evaporator, on the contrary, works at low pressure, and the refrigerant contained therein is mainly a liquid-vapour mixture and a superheated vapour, so its density is quite low. It has been observed that limiting to <NUM> the refrigerant charge could negatively affect the performances of the heat pump system, in particular its energy efficiency.

There is the need, therefore, to reduce the volume of the components of the heat exchangers wherein the refrigerant flows, so as to limit the refrigerant charge required by the system. On the other hand, it's important not reducing too much the external surface area, so as to keep a good heat exchange performance.

A known kind of heat exchanger, widely used in heat pump systems of laundry treating appliances, comprises a plurality of fins, typically made of aluminum and having a rectangular plane, stacked in spaced and parallel planes; the fins comprise a plurality of through-holes wherein a plurality straight pipes, made of copper or aluminum, parallel one another and perpendicular to the fins, are fitted, with their lateral surface into close contact with the border of the through-holes, so as to obtain an effective heat-exchange.

The straight pipes are connected in twos, at one end, by a curved pipe, to define as a whole a single duct wherein the refrigerant flows; this single duct has an inlet portion and an outlet portion protruding from the stack of fins, and connectable to the rest of the heat pump system circuit. During the functioning of the heat pump system, the operating fluid flows through the gaps between the fins, exchanging heat with the latter, and therefore with the refrigerant flowing in the pipes, which are thermally connected to the fins.

The fins used for producing such heat exchangers are typically produced and sold with standardized dimensions, and with a fixed number of through-holes; the producers of laundry treating appliances using such a kind of heat exchangers, in order to keep reduced the production costs, typically purchase the available fins having external dimensions (i.e. length and width) suitable for their appliances, stack them in spaced and parallel planes, and insert in all the through-holes the same number of straight pipes; typically the pipes are fastened to the through-holes by radially expanding such pipes by suitable tools. Then, the straight pipes are connected in twos, at one end, by a curved pipe, to define as a whole the single duct wherein the refrigerant flows.

Since the external dimensions of the fins and the number of through-holes is fixed, the freedom of design is very small. In particular, in order to reduce the overall volume of the single duct wherein the refrigerant flows, there is the possibility to reduce the number of stacked fins, and therefore the length of the straight pipes composing the single duct; unfortunately, reducing the number of fins reduces also the overall thermal exchange surface of the heat exchanger, which reduces the energy efficiency of the heat pump system.

<CIT> discloses a heat exchanger, in particular for a heat pump dryer, having at least one tube bent in a meandering shape for the passage of a first medium to be cooled or heated; between the tube there are lamellar layers for the passage of a second medium to be heated or cooled, wherein the layers are connected to one another via layer connecting pieces; recesses are provided, in which partial cross-sections of the respective tube sections of the tube are accommodated. <CIT> discloses a heat pump designed for a household appliance, in particular laundry treatment appliance, comprising a rotary compressor, a condenser, a restrictor, and an evaporator, wherein the condenser is of an expanded tube- and-fin type with the tubes having an outer diameter of less than <NUM> and wherein the roller has a height-to-radius ratio of <NUM> to <NUM>.

<CIT> discloses a clothes treatment apparatus, including a drum rotatably provided within a cabinet to accommodate washing and drying objects; and a heat pump including an evaporator, a compressor, a condenser, and an expansion valve, through which refrigerant is circulated, to provide heat to air discharged from the drum and circulated to the drum, wherein the heat pump further includes an internal heat exchanger configured to exchange heat between refrigerant discharged from the condenser and refrigerant passing through the evaporator.

The aim of the present invention is therefore obtaining a laundry treating appliance using a heat pump system, having a reduced Global Warming Potential (GWP) and an improved efficiency, and at the same time keeping reduced the production costs.

Within this aim, a further object of the invention is obtaining a laundry treating appliance fulfilling the safety regulations related to the refrigerant of the heat pump system, without reducing the overall energy efficiency, and and at the same time keeping reduced the production costs. Applicant has found that, by leaving empty (i.e. not inserting pipes therein) two or more through-holes of the fins of a heat exchanger of the heat pump system, it is possible reducing the overall internal volume of the single duct of the heat exchanger wherein the refrigerant flows without reducing the length of the single pipes composing such a single duct nor the number of fins, and therefore without reducing the overall thermal exchange surface, also using standard fins available in the market having a prefixed number of through-holes, and so without using customized fins which could increase the production costs.

This inventive solution allows using in the heat pump system a flammable refrigerant, like for example propane (R290) or propylene (R1270), which have a very low Global Warming Potential (GWP), but that needs to be used in small quantities, and therefore requires a reduced volume of the single duct of the heat exchanger wherein the refrigerant flows.

In particular, above aim is solved by a laundry treating appliance comprising:.

Advantageously, the four or more through-holes of any fin of the plurality of fins are respectively aligned with the four or more through-holes of the rest of the plurality of fins.

In an advantageous embodiment, the stacked fins comprise perimeter edges defining as a whole an envelope surface (i.e. a surface that is tangent to the perimeter edges of all the stacked fins) comprising at least a plane portion, and wherein the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion, or to define at least one first row perpendicular to the plane portion and at least one second row perpendicular to the first row.

In a preferred embodiment, the stacked fins comprise perimeter edges defining as a whole an envelope surface comprising at least a plane portion, and wherein the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion and at least one second row perpendicular to the first row, and wherein the at least two through-holes of the four or more through-holes not housing any of the metallic pipes belong to a same second row.

More preferably, in the same second row, between at least two through-holes not housing any of the metallic pipes there is at least one of the through-holes housing one of the metallic pipes; this advantageous embodiment ensures that the distribution of the metallic pipes with respect to the fins is quite uniform, and therefore that the heat distribution within the heat exchanger is quite uniform.

In a further advantageous embodiment, at least two through-holes of the four or more through-holes not housing any of the metallic pipes belong to a same first row.

Preferably, in this case in this same first row, between the at least two through-holes not housing any of the metallic pipes there is at least one of the through-holes housing one of the metallic pipes; also this advantageous embodiment ensures that the distribution of the metallic pipes with respect to the fins is quite uniform, and therefore that the heat distribution within the heat exchanger is quite uniform. In a further advantageous embodiment, the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion and at least one second row perpendicular to the first row, and the fins comprise at least two second rows, and at least two through-holes of the four or more through-holes not housing any of the metallic pipes belong to two contiguous second rows.

In a further advantageous embodiment, the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion, wherein the fins comprise at least two perpendicular rows, and at least two through-holes of the four or more through-holes not housing any of the metallic pipes belong to two contiguous perpendicular rows.

It is underlined that stating that two rows are contiguous means that there aren't other rows positioned between such two rows.

In another advantageous embodiment, the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion, and wherein all the through-holes of the at least one first row do not house any of the metallic pipes.

In a further advantageous embodiment, the four or more through-holes of each of the fins are positioned on the respective fin to define at least one first row perpendicular to the plane portion and at least one second row perpendicular to the first row, and wherein all the through-holes of the at least one first row and/or of the at least one second row do not house any of the metallic pipes.

Further preferably, the single duct comprises an inlet portion and an outlet portion configured for allowing said flammable refrigerant respectively to enter/exit said single duct.

More preferably, the inlet portion and the outlet portion protrude both from a same terminal fin of the plurality of fins.

Preferably, the flammable refrigerant is or comprises a hydrocarbon.

More preferably, the flammable refrigerant is or comprises propane (R290) or propylene (R1270).

In a preferred embodiment, the fins are made of metal.

More preferably, the fins and/or the metallic pipes are made of, or comprise, aluminum or aluminum alloy, or copper, or copper alloy.

In an advantageous embodiment, the laundry treating appliance is a tumble drier or washer-drier, and the operating fluid is air.

In another advantageous embodiment, the laundry treating appliance is a laundry washing machine, and the operating fluid is water, or water mixed with a washing/rinsing agent. Other advantages and features of a laundry treating appliance according to the present invention will be clear from the following detailed description, provided only as a not limitative example, in which:.

In the figures, same parts are indicated with the same reference numbers.

Advantageously, the laundry treating appliance <NUM> illustrated in <FIG> is a tumble drier of the "horizontal axis type"; it is however clear that the invention can be applied, without any substantial modification, also to tumble driers of the vertical axis" type, and to washing machines and washer driers, both of the "horizontal axis" and of the "vertical axis" type.

The laundry treating appliance (being it a tumble drier <NUM>, or a washing machine or washer-drier, not illustrated) comprises a cabinet <NUM>, or housing, preferably parallelepiped, configured to be positioned on a horizontal surface <NUM>, for example the floor of a building, preferably by suitable feet <NUM>, one or more of which can have, advantageously, an adjustable height, so as to adapt to a possible not perfect planarity of the horizontal surface <NUM>.

Advantageously, in the frontal wall 20a of the cabinet <NUM> an access opening, not illustrated, is preferably obtained, advantageously selectively closable by a loading/unloading door <NUM>, preferably hinged to the frontal wall 20a.

The laundry treating appliance (being it a tumble drier <NUM>, or a washing machine or washer-drier) comprises a drum <NUM> rotatably housed within the cabinet <NUM>, in which the laundry, not illustrated, can be loaded.

If the laundry treating appliance is a washing machine or a washer-drier, both not illustrated, the cabinet <NUM> also houses a washing tub, not illustrated, preferably suspended to the cabinet through springs and dumpers, also not illustrated, in which the drum <NUM> is rotatably contained.

The laundry treating appliance <NUM> comprises a circulating system <NUM> configured for circulating an operating fluid through the drum <NUM>.

It is underlined that the circulating system <NUM> can define a closed circuit for the operating fluid (i.e. the operating fluid remains within the closed circuit during the laundry treating process, and the same fluid, opportunely treated, passed repeatedly through the drum <NUM>), or it can define an opened circuit for the operating fluid (i.e. the operating fluid is loaded within the laundry treating appliance <NUM> at a certain point of the laundry treating process, and it is drained from the laundry treating appliance <NUM> at another point of the laundry treating process).

In the advantageous embodiment in which the laundry treating appliance <NUM> is a tumble drier, like the advantageous example of <FIG>, or a washer drier, not illustrated, the operating fluid is or comprises air (represented by arrows <NUM>), and the circulating system preferably comprises an air circuit <NUM> and one or more fans <NUM> configured for circulating such air <NUM> through the drum <NUM> and the air circuit <NUM>.

If the laundry treating appliance is a tumble drier <NUM>, it can also advantageously comprise a lint filter <NUM>, arranged in the air circuit <NUM> for trapping lint or fluff released from the laundry.

If the laundry treating appliance is a washing machine or a washer drier, both not illustrated, the operating fluid is or comprises water, or water mixed with a washing/rinsing additive, and the circulating system preferably comprises a water inlet circuit, not illustrated, adapted to feed water into the tub, also not illustrated, and a drain circuit, also not illustrated, adapted for draining washing/rinsing liquid from the machine.

The laundry treating appliance <NUM> advantageously comprises a heat pump system <NUM>, configured for heating the operating fluid, for example, in case of a tumble drier, the air <NUM>. Advantageously, the heat pump system <NUM> can also be configured for cooling and dehumidifying the operating fluid.

Preferably, the heat pump system <NUM> comprises a compressor, not illustrated, an expansion valve, also not illustrated, two heat exchangers 70a, 70b (one operating as a condenser, and the other as an evaporator), and conduits, not illustrated, fluidly connecting such elements in a closed circuit.

A flammable refrigerant flows through the compressor, the condenser 70a, the expansion valve and the evaporator 70b, and through the conduits connecting these to one another.

The flammable refrigerant releases heat to the operating fluid by means of the condenser 70a and extracts heat and humidity from the operating fluid by means of the evaporator 70b. The compressor converts electromechanical power to thermal power by compressing the flammable refrigerant in the refrigerant circuit.

The flammable refrigerant is or comprises a hydrocarbon, preferably propane (R290) or propylene (R1270). Advantageously, the heat exchangers, for example the condenser 70a and/or the evaporator 70b, comprise a plurality of metallic pipes <NUM> (called also simply pipes) wherein the flammable refrigerant flows, and a plurality of fins <NUM> (advantageously metallic), stacked spaced and parallel to one another, each provided with four or more through-holes <NUM> suitable for housing one of the metallic pipes <NUM>. Advantageously, the through-holes <NUM> of any fin <NUM> are respectively aligned with the through-holes <NUM> of the rest of the fins <NUM>.

Advantageously, the perimeter edges <NUM> of the stacked fins <NUM> define as a whole an envelope surface, illustrated in figures and <NUM> with a dotted line numbered <NUM>, comprising at least a plane portion <NUM>.

Preferably, the fins <NUM> have a rectangular or square plan, in which case the envelope surface <NUM> comprises four plane portions, corresponding to the four sides of the rectangle or square.

Preferably, the width of the fins <NUM> is comprised between <NUM> and <NUM>, more preferably between <NUM> and <NUM>. Preferably, the height of the fins <NUM> is comprised between <NUM> and <NUM>, more preferably between <NUM> and <NUM>. Preferably, the overall length of the stacked fins <NUM> is comprise between <NUM> and <NUM>, more preferably between <NUM> and <NUM>.

Advantageously, the fins <NUM> are made of, or comprise, aluminum or aluminum alloy, or copper, or copper alloy.

Advantageously, the more metallic pipes <NUM> are made of, or comprise, aluminum or aluminum alloy, or copper or copper alloy.

The metallic pipes <NUM> comprise two or more straight pipes <NUM>, parallel one another and perpendicular to the fins <NUM>, each one of the two or more straight pipes <NUM> being housed in one of the through-holes <NUM> of the fins <NUM>.

The straight pipes <NUM> are fitted, with their lateral surface into close contact with the border of the respective through-holes <NUM>, so as to obtain an effective heat-exchange between them; this can be obtained by radially expanding such straight pipes <NUM> by suitable tools, not illustrated.

The two or more straight pipes <NUM> are connected in twos, at one end thereof, by a curved pipe <NUM>, to define as a whole a single duct <NUM> wherein the flammable refrigerant flows.

Such a single duct <NUM> advantageously comprises an inlet portion <NUM> and an outlet portion <NUM>, configured for allowing the flammable refrigerant respectively to enter/exit the single duct; advantageously, the inlet portion <NUM> and the outlet portion <NUM> are fluidly connected or connectable to the other elements of the heat pump system <NUM>, so as to allow circulation of the flammable refrigerant through the respective heat exchanger 70a or 70b.

Advantageously, like in the examples of attached figures, the inlet portion <NUM> and an outlet portion <NUM> protrude both from a same terminal fin <NUM> of the plurality of fins <NUM>, which simplifies the connection of the single duct <NUM> to the other conduits of the heat pump system <NUM>.

Advantageously, at least two through-holes <NUM> of the four or more through-holes <NUM> of each fin <NUM> houses one of the metallic pipes <NUM>.

Advantageously, at least two through-holes <NUM> of the four or more through-holes <NUM> of each fin <NUM> do not house any of the metallic pipes <NUM> (or in other words they are not crossed by any metallic pipe <NUM>, or are free, or empty, from metallic pipes <NUM>).

In this way, the number of metallic pipes <NUM>, and therefore the overall internal volume of the single duct <NUM> composed of such metallic pipes <NUM>, wherein the flammable refrigerant flows, is reduced, while the number of fins <NUM>, and therefore the overall length of their stack, can be relatively high, so as to obtain a desired overall thermal exchange surface.

In an advantageous embodiment, four or more through-holes <NUM> of each fin <NUM> are positioned on the respective fin <NUM> to define at least one first row <NUM> perpendicular to the plane portion <NUM> of the envelope surface <NUM> and/or at least one second row <NUM> perpendicular to the first rows <NUM>.

For example, in case four through-holes <NUM>, they can be all aligned along to a single first row <NUM>, or they can be all aligned along a single second row <NUM>, or they can be positioned, as illustrated for example in <FIG>, each at a vertex of a rectangle or square, so as to define, as a whole, two first rows <NUM> and two second rows <NUM>.

In advantageous embodiments, like for example the ones illustrated in <FIG>, <FIG> and <FIG>, at least two through-holes of the four or more through-holes <NUM> not housing any of the pipes <NUM> belong to a same second row <NUM>.

In an advantageous embodiment, like for example the one illustrated in <FIG>, in a same second row <NUM>, between at least two through-holes <NUM> not housing any metallic pipes <NUM> there is at least one through-hole <NUM> housing one metallic pipes <NUM>.

In advantageous embodiments, like for example the one illustrated in <FIG>, at least two through-holes <NUM> of the four or more through-holes <NUM> not housing any metallic pipe <NUM> belong to a same first row <NUM>.

In a preferred embodiment, like for example the one illustrated in <FIG>, in a same first row <NUM>, between two through-holes <NUM> not housing any metallic pipes <NUM> there is at least one through-hole <NUM> housing one metallic pipe <NUM>. Preferably, the fins <NUM> comprise at least two second rows <NUM>, and, like for example ion the advantageous embodiments of <FIG> and <FIG>, at least two through-holes <NUM> not housing any metallic pipe <NUM> belong to two contiguous second rows <NUM>. In a further advantageous embodiment, the fins <NUM> comprise at least two of first rows <NUM>, and, like for example in the advantageous embodiments of <FIG> and <FIG>, at least two through-holes <NUM> not housing any metallic pipe <NUM> belong to two contiguous first rows <NUM>.

In a further advantageous embodiment, not illustrated, all the through-holes <NUM> of a first row <NUM> and/or of one second row <NUM> do not house any of metallic pipe <NUM>.

Anyway, different positionings of the at least two through-holes <NUM> are possible.

Claim 1:
A laundry treating appliance (<NUM>) comprising:
- a cabinet (<NUM>);
- a drum (<NUM>), rotatably housed within said cabinet (<NUM>), in which laundry can be loaded;
- a heat pump system (<NUM>), using one or more flammable refrigerants, configured for exchanging heat with an operating fluid (<NUM>);
- a circulating system (<NUM>) configured for circulating said operating fluid (<NUM>) through said drum (<NUM>);
wherein said heat pump system (<NUM>) comprises a heat exchanger (70a, 70b) comprising:
- a plurality of metallic pipes (<NUM>) wherein said flammable refrigerant flows;
- a plurality of fins (<NUM>), stacked, spaced and parallel to one another, each provided with four or more substantially circular through-holes (<NUM>) suitable for housing one of said metallic pipes (<NUM>) and having a closed perimeter,
wherein said straight pipes (<NUM>) are radially expanded so as to fit with their lateral surface into close contact with the border of said respective through-hole (<NUM>), in such a way to obtain an effective heat-exchange between them,
wherein each of at least two through-holes (<NUM>) of said four or more through-holes (<NUM>) of each one of said fins (<NUM>) houses one of said metallic pipes (<NUM>),
wherein said metallic pipes (<NUM>) comprise two or more straight pipes (<NUM>), parallel one another and perpendicular to said fins (<NUM>), each one of said two or more straight pipes (<NUM>) being housed in one of said four or more through-holes (<NUM>) of said fins (<NUM>), said two or more straight pipes (<NUM>) being connected in twos, at one end, by a curved pipe (<NUM>), to define as a whole a single duct (<NUM>) wherein said flammable refrigerant flows,
characterized in that
at least two through-holes (<NUM>) of said four or more through-holes (<NUM>) of each one of said fins (<NUM>) do not house any of said metallic pipes (<NUM>).