EP2631352A1

EP2631352A1 - Rotary-drum laundry dryer

Info

Publication number: EP2631352A1
Application number: EP12157171.5A
Authority: EP
Inventors: Marco Costantin; Marco Santarossa; Alessandro Vian
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2012-02-27
Filing date: 2012-02-27
Publication date: 2013-08-28
Anticipated expiration: 2032-02-27
Also published as: WO2013127656A1; EP2631352B1

Abstract

Rotary-drum laundry dryer (1) comprising an outer casing (2) having a front wall (2a) and a rear wall (2b), a substantially cylindrical, sleeve-shaped rotatable drum (3) which is structured for housing the laundry to be dried and is fixed in axially rotating manner inside the casing (2), and a hot-air generator (6) structured to circulate a stream of hot air through the rotatable drum (3); said rotatable drum (3) comprising a substantially cylindrical, tubular body (3) having its front rim (3f) coupled in axially rotating manner to the front wall (2a) of the casing (2) and its rear rim (3r) coupled in substantially airtight and axially rotating manner to the rear wall (2b) of the casing (2) with the interposition of a rear circular sealing gasket (10); the rotary-drum laundry dryer (1) being characterized in that the rear wall (2b) of the casing (2) comprises: a substantially vertically-oriented supporting bulkhead (12), and a lid or cover (13) which is made of plastic material and is fixed in substantially airtight manner to the supporting bulkhead (12) so as to form, together with said supporting bulkhead (12), an inner cavity (15) which is fluidly connected to the hot-air generator (6) so as to receive said stream of hot air; the lid or cover (13) being furthermore shaped so that the peripheral border (12a) of the lid or cover completely surrounds the rear rim (3r) of the tubular body (3), and a central portion (13c) of the lid or cover (13) being permeable to air so that the stream of hot air is allowed to cross the lid or cover (13) and flow from the inside of the tubular body (3) to the inner cavity (15) or vice versa; the rear wall (2b) of the casing (2) moreover comprising a substantially cylindrical gasket-supporting collar (16) which has a nominal diameter greater than that of the rear rim (3r) of the tubular body (3), is realized in one piece with said lid or cover (13) and is arranged on the lid or cover (13) so as to be substantially coaxial to the rear rim (3r) of said tubular body (3).

Description

The present invention relates to a rotary-drum laundry dryer.
In particular, the present invention relates to a rotary-drum home laundry dryer to which the following description refers purely by way of example without implying any loss of generality.
As is known, rotary-drum home laundry dryers currently on the market generally comprise: a substantially parallelepiped-shaped, outer boxlike casing structured for resting on the floor; a substantially cylindrical rotatable drum which is structured for housing the laundry to be dried and is housed in axially rotating manner inside the casing to rotate about an horizontally-oriented longitudinal reference axis, directly facing a laundry loading/unloading opening formed in the front wall of the casing; a porthole door hinged to the front wall of the casing to rotate to and from a closing position in which the door rests completely against the front wall of the casing to close the laundry loading/unloading opening and airtight seal the rotatable drum; an electrically-powered motor assembly which is housed inside the casing and is structured for driving into rotation the rotatable drum about its longitudinal reference axis; an open-circuit or closed-circuit, hot-air generator which is housed inside the casing and is structured to circulate inside the rotatable drum a stream of hot air which has a very low moisture content and flows through the rotatable drum and over the laundry inside the drum to dry the laundry; and an electronic central control unit which controls both the motor assembly and the hot-air generator to perform, on command, one of the user-selectable drying cycles stored in the same central control unit.
In most of the rotary-drum home laundry dryers currently on the market, the rotatable drum furthermore consists in a substantially cylindrical, rigid tubular body which extends substantially horizontally inside the boxlike casing, aligned to the laundry loading/unloading opening, and is structured for resting on a number of idle supporting rollers which are arranged at the two axial ends of the tubular body parallel to the drum longitudinal reference axis, and may be fixed to the appliance casing in free revolving manner so as to allow the tubular body to rotate about its horizontally-oriented longitudinal reference axis.
The front rim of the tubular body surrounds the laundry loading/unloading opening and is coupled in axially rotating manner to the front wall of the boxlike casing; whereas the rear rim of the tubular body abuts against the rear wall of the boxlike casing and is coupled in axially rotating manner directly to said rear wall.
The stream of hot air produced by the hot-air generator usually enters into the tubular body via an intake air-vent realized in the rear wall of the boxlike casing, within the perimeter of the rear rim of the tubular body, flows inside the tubular body for the entire length of the latter, and finally comes out of the tubular body via an escape air-vent usually realized on the annular frame that delimits the laundry loading/unloading opening on the front wall of the casing.
To avoid air leakages from the two axial ends of the tubular body, a first circular sealing gasket is generally interposed between the front rim of the tubular body and the front wall of the casing, whereas a second circular sealing gasket is generally interposed between the rear rim of the tubular body and the rear wall of the appliance casing.
In most of the rotary-drum home laundry dryers currently on market, the first circular sealing gasket is usually recessed into a circular groove realized on the front wall of the casing and is firmly fixed to the bottom of the groove so as to remain stationary when the rotatable drum rotates about its longitudinal reference axis. The second circular sealing gasket instead is usually fixed to a cylindrical supporting collar which in turn is generally clinched to the rear wall of the boxlike casing coaxial to the rear rim of the tubular body. Alike the first circular sealing gasket, the second circular sealing gasket is firmly fixed to the inner surface of the cylindrical supporting collar so as to remain stationary when the rotatable drum rotates about its longitudinal reference axis.
Since the back of the rotatable drum consists in the rear wall of the boxlike casing and remains stationary during rotation of the rotatable drum, most of the laundry dryers referred above are also provided with an anti-entangling nose that protrudes from the rear wall of the casing roughly at centre of the rear rim of the tubular body, and extends inside the tubular body substantially parallel to the drum longitudinal reference axis. This nose is shaped/dimensioned so to prevent, when the drum rotates, the laundry from entangling on the rear wall of the casing and block the hot-air intake vent located on said wall.
Aim of the present invention is to simplify the structure of the rear wall of the boxlike casing so as to significantly reduce the appliance production costs, and simplifying the laundry dryer assembling procedure.
In compliance with the above aims, according to the present invention there is provided a rotary-drum laundry dryer comprising an outer casing having a front wall and a rear wall, a rotatable drum which is structured for housing the laundry to be dried and is fixed in axially rotating manner inside the casing, and a hot-air generator structured to circulate a stream of hot air through the rotatable drum; said rotatable drum comprising a substantially cylindrical, tubular body having its front rim coupled in axially rotating manner to a front bulkhead and its rear rim coupled in substantially airtight and axially rotating manner to the rear wall of the casing with the interposition of a rear circular sealing gasket; the rotary-drum laundry dryer being characterized in that the rear wall of the casing comprises:

a substantially vertically-oriented supporting bulkhead;
a lid or cover which is made of plastic material and is fixed to the supporting bulkhead so as to form, together with said supporting bulkhead, an inner cavity which is fluidly connected to the hot-air generator so as to receive said stream of hot air; a central portion of the lid or cover being permeable to air so that the stream of hot air is allowed to cross the lid or cover and freely flow from the inside of the tubular body to the inner cavity or vice versa; and
a substantially cylindrical gasket-supporting collar which has a nominal diameter greater than that of the rear rim of the tubular body, is realized in one piece with said lid or cover and is arranged on the lid or cover so as to be substantially coaxial to the rear rim of the tubular body for completely surrounding the rear rim of the tubular body;

Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said gasket-supporting collar is realized in one piece with said lid or cover via an injection molding process.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said lid or cover is fixed to the inner face of the supporting bulkhead in substantially airtight manner.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized by also comprising an anti-entangling nose which protrudes from the lid or cover, extends inside the tubular body and is properly shaped/dimensioned so as to prevent, when the tubular body rotates, the entangling of the damp laundry located into the rotatable drum.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said anti-entangling nose is realized in one piece with said lid or cover and said gasket-supporting collar.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said anti-entangling nose consist in a substantially ogival-shaped bulge or recess which projects from the lid or cover, on the opposite side of supporting bulkhead, and extends inside the tubular body.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said lid or cover is substantially circular in shape, has an outer diameter greater than that of the rear rim of the tubular body, and is fixed to the supporting bulkhead substantially coaxial to the longitudinal axis of the tubular body.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the peripheral border of the lid or cover is furthermore L-bent upwards so as to form said cylindrical gasket-supporting collar.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said lid or cover is substantially dish- or basin-shaped and it is fixed to the inner face of the supporting bulkhead with its concavity directly facing the supporting bulkhead, so as to form, together with the gasket-supporting collar, a substantially circular-shaped annular seat or groove which is shaped/dimensioned to house the rear circular sealing gasket.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the supporting bulkhead is provided with a substantially sink-shaped bulge or recess which is aligned/faced to a rear mouth of the tubular body delimited by said rear rim, projects outwards of the casing and communicates with the hot-air generator; the lid or cover being fixed to the supporting bulkhead immediately above said outwards-projecting bulge or recess, and being shaped/dimensioned to completely cover and close said outwards-projecting bulge or recess to form the inner cavity of the rear wall of the casing.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the outwards-projecting, sink-shaped bulge or recess is substantially circular in shape and has an outer diameter lower than that of the rear circular sealing gasket and of the rear rim of tubular body, so as to be located inside the perimeter of the rear rim of the tubular body.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the lid or cover is firmly fixed to the supporting bulkhead with the interposition of an additional annular sealing gasket.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said lid or cover is firmly fixed to the supporting bulkhead by means of a number of fixing members, such as anchoring screws, rivets or the like, that engage in sequence the supporting bulkhead and the lid or cover.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said fixing members are angularly spaced along the peripheral border of the lid or cover, outside of the additional annular sealing gasket.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the gasket-supporting collar is provided with a number of anchoring seats which are spaced along the perimeter of the same collar, and each of which is structured to receive a respective anchoring screw, rivet or other fixing member.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the supporting bulkhead is made of metal material.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that the hot-air generator comprises a heat-pump assembly structured for continuously cooling and then heating the air circulating inside the rotatable drum.
Preferably, though not necessarily, the rotary-drum laundry dryer is furthermore characterized in that said substantially cylindrical-shaped, tubular body is structured for resting on a number of idle supporting rollers which are arranged approximately at the two axial ends of the tubular body, and may be preferably fitted/fixed to the casing in free revolving manner. so as to allow the tubular body to freely rotate about its longitudinal reference axis inside the casing.
A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figures 1 and 2 are two perspective views, with parts removed for clarity, of a rotary-drum laundry dryer realized in accordance with the teachings of the present invention;
Figure 3 is a section view of the Figure 1 laundry dryer with parts removed for clarity;
Figure 4 is a partly-exploded perspective view of the rear wall of the

Figure 1 laundry dryer with parts removed for clarity.
With reference to Figures 1, 2 and 3, reference number 1 indicates as a whole a rotary-drum laundry dryer which comprises: a preferably, though not necessarily, parallelepiped-shaped, outer boxlike casing 2 structured for resting on the floor; a substantially cylindrical, rotatable drum 3 structured for housing the laundry to be dried, and which is fixed in axially rotating manner inside the outer casing 2, directly facing a laundry loading/unloading pass-through opening formed in a preferably substantially vertically-oriented, front wall 2a of casing 2; and a porthole door 4 hinged to the front wall 2a of casing 2 so to be able to rotate about a preferably, though not necessarily, vertically-oriented reference axis, to and from a closing position in which door 4 rests completely against the front wall 2a to close the laundry loading/unloading opening and substantially airtight seal the rotatable drum 3.
Inside the boxlike casing 2, the laundry dryer 1 additionally comprises an electrically-powered motor assembly (not shown) structured for driving into rotation the rotatable drum 3 about its longitudinal reference axis; an open-circuit or closed-circuit, hot-air generator 6 which is structured to circulate through the rotatable drum 3 a stream of hot air having a low moisture level, and which flows over and dries the laundry located inside the drum 3; and an electronic central control unit (not shown) which controls both the electrically-powered motor assembly and the hot-air generator 6 to perform, on command, one of the user-selectable drying cycles preferably, though not necessarily, stored in the same central control unit.
With reference to Figure 3, in particular the rotatable drum 3 preferably consists in a substantially cylindrical-shaped, tubular body 3 which extends inside the boxlike casing 2 coaxial to a preferably substantially horizontally-oriented, longitudinal reference axis L while remaining substantially aligned to the laundry loading/unloading opening on the front wall 2a of casing 2. The tubular body 3 is furthemore preferably structured for resting on a number of idle supporting rollers 8 which are arranged approximately at the two axial ends of tubular body 3 substantially parallel to the reference axis L, and are preferably fitted/fixed to the boxlike casing 2 in free revolving manner so as to allow the tubular body 3 to rotate about its longitudinal reference axis L inside the boxlike casing 2. The substantially cylindrical-shaped, tubular body 3 is preferably made of metal material.
The circular front rim 3f of tubular body 3 surrounds the laundry loading/unloading opening realized on front wall 2a of the boxlike casing 2 and is coupled in substantially airtight and axially rotating manner to a front panel or bulkhead 12 on the front wall 2a, preferably with the interposition of a first circular sealing gasket 9. The circular rear rim 3r of tubular body 3 instead abuts against a preferably substantially vertically-oriented, rear wall 2b of casing 2 and is coupled in substantially airtight and axially rotating manner directly to said rear wall 2b with the interposition of a second circular sealing gasket 10.
In the example shown, the circular sealing gasket 9 is preferably, though not necessarily, stationary recessed into a circular groove or seat realized on the periphery of a front panel or bulkhead 11 preferably comprising a substantially funnel-shaped coupling element, and which is preferably associated to the front wall 2a of casing 2 so as to surround the laundry loading/ unloading opening of the same front wall 2a. The substantially funnel-shaped coupling element of front bulkhead 11 is furthermore preferably shaped/structured so as to directly connect the laundry loading/unloading opening of front wall 2a to the front rim 3f of tubular body 3, and the front rim 3f of tubular body 3 abuts directly against said front circular sealing gasket 9.
The second circular sealing gasket 10 is instead firmly fixed to the rear wall 2b of the boxlike casing 2.
With reference to Figure 3, the stream of hot air produced by the hot-air generator 6 preferably enters into the tubular body 3 through the mouth delimited by the rear rim 3r of tubular body 3, flows inside tubular body 3 for the entire length of the latter, and comes out of tubular body 3 through the mouth delimited by the front rim 3a, or vice versa.
In other words, the stream of hot air produced by the hot-air generator 6 preferably enters into tubular body 3 through an intake air-vent located in the rear wall 2b of casing 2, within the perimeter of the rear rim 3r of tubular body 3, and comes out of tubular body 3 through an escape air-vent preferably located either on the porthole door 4 that selectively closes the laundry loading/unloading opening of front wall 2a or directly on the front wall 2a.
In the example shown, the stream of hot air produced by hot-air generator 6 preferably comes out of tubular body 3 through an escape air-vent incorporated in the front bulkhead 11 that delimits/surrounds the laundry loading/unloading opening on front wall 2a.
With reference to Figures 3 and 4, the intake air-vent of hot-air generator 6 is instead incorporated into the rear wall 2b of boxlike casing 2.
Furthermore, the rear wall 2b of boxlike casing 2 preferably comprises a vertically-oriented supporting panel or bulkhead 12 which is preferably made of metal material and is preferably provided with a substantially sink-shaped bulge or recess 12a which, in turn, is aligned/faced to the rear mouth of tubular body 3 delimited by rear rim 3r, projects outwards of boxlike casing 2 and is in fluid communication with the hot-air generator 6 so as to receive the stream of hot air produced by the hot-air generator 6.
In the example shown, the sink-shaped bulge or recess 12a is preferably substantially circular in shape and preferably projects outwards of the boxlike casing 2 while remaining substantially coaxial to the longitudinal axis L of the tubular body 3. Furthermore the sink-shaped bulge or recess 12a has an outer diameter preferably lower than that of the circular sealing gasket 10 and of the rear rim 3r of tubular body 3, so as to be located inside the perimeter of the rear rim 3r of tubular body 3. The sink-shaped bulge or recess 12a is furthermore preferably deep-drawn directly on the supporting bulkhead 12.
The rear wall 2b of boxlike casing 2 additionally comprises a lid or cover 13 which is firmly fixed to the inner face of the supporting bulkhead 12 above the outwards-projecting bulge or recess 12a of the same bulkhead 12 (i.e. it is aligned/faced to the rear mouth of tubular body 3 delimited by rear rim 3r), is properly shaped/dimensioned to completely cover the outwards-projecting bulge or recess 12a of bulkhead 12, and is coupled in substantially airtight manner to the supporting bulkhead 12, preferably with the interposition of an annular sealing gasket 14 surrounding the perimeter of bulge or recess 12a, so as to form/delimit, together with the supporting bulkhead 12, a inner cavity 15 which is preferably substantially circular-shaped and is aligned to the rear mouth of tubular body 3 delimited by rear rim 3r, and is fluidly connected to the hot-air generator 6 so as to receive the stream of hot air produced by the hot-air generator 6.
In the example shown, the inner cavity 15 is preferably arranged inside the rear wall 2b of boxlike casing 2 substantially coaxial to the longitudinal reference axis L of tubular body 3.
With reference to Figures 3 and 4, the lid or cover 13 of rear wall 2b is furthermore preferably suitably shaped/dimensioned so that its peripheral border 13a completely surrounds/circumscribes the rear rim 3r of tubular body 3; and the rear wall 2b of casing 2 additionally comprises a substantially cylindrical gasket-supporting collar 16 which is preferably realized in one piece with the lid or cover 13, preferably has a nominal diameter greater than that of the rear rim 3r of tubular body 3, and is preferably arranged on the lid or cover 13 so as to be substantially coaxial to the longitudinal axis L of tubular body 3 when the lid or cover 13 is fixed in place on the supporting bulkhead 12, i.e. so as to be substantially coaxial to the rear rim 3r of tubular body 3 and surround/circumscribe the rear rim 3r of tubular body 3.
The lid or cover 13 and the gasket-supporting collar 16 are furthermore preferably made of plastic material and are realized in one piece to one another preferably via an injection molding process.
The circular sealing gasket 10 is encircled and fitted/recessed into the gasket-supporting collar 16 preferably in substantially airtight manner, and is suitably shaped/dimensioned so as to permanently come in abutment against the rear rim 3r of tubular body 3 without interruption all around the perimeter of the latter, so as to avoid any air leakage between the rear rim 3r of tubular body 3 and the lid or cover 13.
In the example shown, in particular, the circular sealing gasket 10 is preferably fixed, and/or force-fitted into and/or glued to the gasket-supporting collar 16. Preferably, though not necessarily, the circular sealing gasket 10 is furthermore suitably shaped/dimensioned so as to also abuts against the beneath-located lid or cover 13 without interruption all around the perimeter of the gasket, so as to avoid any air leakage between the circular sealing gasket 10 and the lid or cover 13.
In addition to the above, with reference to Figures 3 and 4, a central portion 13c of the lid or cover 13 faced to the inside of tubular body 3 is furthermore properly perforated, or at any rate structured to be permeable to air, so that the stream of hot air produced by the hot-air generator 6 is allowed to cross the lid or cover 13 and flow from the inside of tubular body 3 to the inner cavity 15 or vice versa.
In the example shown, the lid or cover 13 is preferably substantially circular in shape, preferably has an outer diameter greater than that of rear rim 3r of tubular body 3, and is preferably firmly fixed in substantially airtight manner to the supporting bulkhead 12 substantially coaxial to the longitudinal axis L of tubular body 3, so as to form/delimit, together with the supporting bulkhead 12, a preferably substantially circular-shaped, inner cavity 15 which is arranged inside the rear wall 2b of boxlike casing 2 substantially coaxial to the longitudinal reference axis L of tubular body 3. The peripheral border 13a of the preferably substantially circular-shaped lid or cover 13 is furthermore y L-bent upwards so as to form the cylindrical gasket-supporting collar 16.
Furthermore, the perforated, or at any rate permeable to air, central portion 13c of the lid or cover 13 is preferably substantially circular in shape and is arranged at the centre of the substantially circular-shaped lid or cover 13 so as to be located coaxial to the longitudinal reference axis L of tubular body 3.
With reference to Figures 3 and 4, the lid or cover 13 is furthermore preferably firmly fixed to the supporting bulkhead 12 by means of a number of fixing members, such as anchoring screws, rivets or the like, that preferably engage in sequence the supporting bulkhead 12 and the lid or cover 13 and are preferably angularly spaced along the peripheral border 13a of the lid or cover 13, preferably outside of the annular sealing gasket 14.
In the example shown, the preferably substantially circular-shaped lid or cover 13 is preferably firmly fixed to the supporting bulkhead 12 by means of a number of anchoring screws 17 which are angularly spaced along the circular-shaped peripheral border 13a of the lid or cover 13, i.e. along the gasket-supporting collar 16. Each anchoring screw 17 is furthermore preferably structured so to engage in sequence the supporting bulkhead 12 and the gasket-supporting collar 16.
Furthermore, with reference to Figure 4, the gasket-supporting collar 16 is preferably provided with a number of anchoring seats 17a which are preferably evenly spaced along the perimeter of said collar, and each of which is structured to receive a respective pass-through anchoring screw 17.
In addition to the above, with reference to Figures 3 and 4, the lid or cover 13 is furthermore preferably substantially dish- or basin-shaped and is preferably firmly fixed to the inner face of the supporting panel or bulkhead 12 with its concavity directly facing the bottom of the outwards-projecting bulge or recess 12a of the same bulkhead 12, so as to form, together with the gasket-supporting collar 16, a substantially circular-shaped annular seat or groove 10a which is arranged coaxial to the rear mouth of tubular body 3 and is suitably shaped/dimensioned to house the rear circular sealing gasket 10. Moreover the preferably substantially dish- or basin-shaped lid or cover 13 is shaped/structured so as to form, inside the rear wall 2b of the boxlike casing 2, a preferably substantially circular, lenticular-shaped inner cavity 15 which is crossed by the hot air circulating trough the tubular body 3.
With reference to Figures 3 and 4, the rotary-drum laundry dryer 1 preferably, though not necessarily, also comprises a laundry anti-entangling nose 19 which protrudes from the lid or cover 13 and extends inside the tubular body 3 preferably while remaining substantially coaxial to the longitudinal reference axis L of tubular body 3, and is properly shaped/dimensioned so as to prevent, when tubular body 3 rotates, the entangling of the damp laundry located into the rotatable drum 3. The anti-entangling nose 19 is furthermore preferably substantially frustoconical in shape.
In the example shown, the anti-entangling nose 19 is preferably realized in one piece with the lid or cover 13 and the gasket-supporting collar 16 and preferably, though not necessarily, consists in a preferably substantially ogival-shaped bulge or recess which projects from the center of the lid or cover 13, on the opposite side of supporting bulkhead 12, and extends inside tubular body 3 while remaining substantially coaxial to the longitudinal reference axis L of tubular body 3. Furthermore the ogival-shaped bulge or recess realized at the center of the lid or cover 13 is preferably, though not necessarily, substantially in the shape of a cone.
Alike the gasket-supporting collar 16, the anti-entangling nose 19 is preferably realized in one piece with the lid or cover 13 and the gasket-supporting collar 16 via an injection molding process.
With reference to Figure 3, the hot-air generator 6 of laundry dryer 1 preferably, though not necessarily, consists in a closed-circuit, hot-air generator 6 which is structured for gradually drawing air from rotatable drum 3; cooling down the air arriving from rotatable drum 3 so to extract and retain the surplus moisture in the air drawn from rotatable drum 3; heating the dehumidified air to a predetermined temperature normally higher than the temperature of the air drawn out from rotatable drum 3; and feeding the heated, dehumidified air back into the rotatable drum 3, where it flows over, the laundry inside the drum to rapidly dry said laundry.
In other words, with reference to Figure 3, hot-air generator 6 provides for continually dehumidifying and heating the air circulating inside rotatable drum 3 to rapidly dry the laundry located inside the drum 3, and preferably basically comprises:

an air recirculating conduit 21 having its two ends fluidly connected to the rotatable drum 3 on opposite sides of the latter;
an electrically-powered centrifugal fan 22 or other type of air circulating pump, which is located along the air recirculating conduit 21 to produce, inside the latter, an airflow f which flows in closed loop through the air recirculating conduit 21 and the rotatable drum 3;
air cooling means 23 which are located along the air recirculating conduit 21 preferably, thought not necessarily, downstream of the aforesaid air centrifugal fan 22, and are structured to cool the moist air arriving from rotatable drum 3 so as to cause the condensation of the surplus moisture inside the airflow f; and
air heating means 24 which are located along the air recirculating conduit 21, downstream of the air cooling means 23, and which are structured for heating the dehumidified airflow f arriving from the air cooling means 23 and directed back to rotatable drum 3, so that the airflow f directed back into rotatable drum 3 is heated to a temperature preferably, though not necessarily, higher than or equal to that of the moist air flowing out of rotatable drum 3.

A first end of the air recirculating conduit 21 communicates with, i.e. is fluidly connected to, the inside of the inner cavity 15 of rear wall 2b preferably via a pass-trough opening 12b realized on the bottom of the sink-shaped bulge or recess 12a of supporting bulkhead 12; whereas a second end of the air recirculating conduit 21 directly communicates with, i.e. is fluidly connected to, the inside of tubular body 3 via a second pass-trough opening realized in the funnel-shaped coupling element of front bulkhead 11 that delimits/surrounds the laundry loading/unloading opening of front wall 2a. Thus the airflow f flowing through the air recirculating conduit 21 is forced to circulate in sequence through inner cavity 15 and tubular body 3 or vice versa, before returning back into the air recirculating conduit 21.
In the example shown, hot-air generator 6 is preferably provided with a heat-pump assembly structured for continuously cooling and then heating the air circulating inside the air recirculating conduit 21 and the rotatable drum 3. This heat-pump assembly comprises a first air/refrigerant heat exchanger, traditionally referred to as the "evaporator" of the heat-pump circuit, which is located inside the air recirculating conduit 21, preferably downstream of the centrifugal fan 22, and is structured to remove/absorb heat from the airflow arriving from rotatable drum 3 thus forming the air cooling means 23 of hot-air generator 6; and a second air/refrigerant heat exchanger, traditionally referred to as the "condenser" of the heat-pump circuit, which is located inside the air recirculating conduit 21, downstream of the first air/refrigerant heat exchanger 23, and is structured to release heat to the airflow arriving from the first air/refrigerant heat exchanger thus forming the air heating means 24 of hot-air generator 6.
As an alternative, the air heating means 24 of hot-air generator 6 may comprise a resistor located inside the air recirculating conduit 21, preferably downstream of the centrifugal fan 22, whereas the air cooling means 23 of hot-air generator 6 may comprise an air/air heat exchanger that uses the external air to cool down the airflow arriving from rotatable drum 3.
General operation of the rotary-drum home laundry drier 1 is clearly inferable from the above description, with no further explanation required.
The advantages connected to the particular structure of the rear wall 2b of the boxlike casing 2 are large in number. First of all, a lid or cover 13 made in plastic material and shaped so as to form/incorporate the gasket-supporting collar 16 and optionally also the anti-entangling nose 19, allow to significantly reduce the appliance production costs. Furthermore the one-piece structure greatly simplifies the assembly of the rear wall 2b of the boxlike casing 2.
Clearly, changes may be made to the rotary-drum home laundry drier 1 as described herein without, however, departing from the scope of the present invention.
For example, in a less sophisticated non-shown embodiment the laundry anti-entangling nose 19 may consist of a completely separated, substantially ogival-shaped rigid element which is still preferably made of plastic material, and is rigidly attached to the center of the lid or cover 13 preferably, though not necessarily, via one or more fixing members, such as anchoring screws, rivets or the like, that preferably engage in sequence the body of the lid or cover 13 and the coupling base or socket of said ogival-shaped rigid element.
According to a further non-shown alternative embodiment, the supporting bulkhead 12 of rear wall 2b may be made of plastic material and preferably may be realized via an injection molding process.
According to a still further non-shown alternative embodiment, the supporting bulkhead 12 of rear wall 2b may lack the sink-shaped bulge or recess 12a. In which case , the substantially dish- or basin-shaped lid or cover 13 is firmly fixed to the supporting bulkhead 12 with its concavity directly facing the supporting bulkhead 12, so as to form, inside the rear wall 2b of the boxlike casing 2, a substantially lenticular-shaped inner cavity 15 which is crossed by the hot air circulating trough the tubular body 3.

Claims

Rotary-drum laundry dryer (1) comprising an outer casing (2) having a front wall (2a) and a rear wall (2b), a rotatable drum (3) which is structured for housing the laundry to be dried and is fixed in axially rotating manner inside the casing (2), and a hot-air generator (6) structured to circulate a stream of hot air through the rotatable drum (3); said rotatable drum (3) comprising a substantially cylindrical, tubular body (3) having its front rim (3f) coupled in axially rotating manner to a front bulkhead (11) and its rear rim (3r) coupled in substantially airtight and axially rotating manner to the rear wall (2b) of the casing (2) with the interposition of a rear circular sealing gasket (10);
the rotary-drum laundry dryer (1) being characterized in that the rear wall (2b) of the casing (2) comprises:
- a substantially vertically-oriented supporting bulkhead (12);

- a lid or cover (13) which is made of plastic material and is fixed to the supporting bulkhead (12) so as to form, together with said supporting bulkhead (12), an inner cavity (15) which is fluidly connected to the hot-air generator (6) so as to receive said stream of hot air; a central portion (13c) of the lid or cover (13) being permeable to air so that the stream of hot air is allowed to cross the lid or cover (13) and flow from the inside of the tubular body (3) to the inner cavity (15) or vice versa; and

- a substantially cylindrical gasket-supporting collar (16) which has a nominal diameter greater than that of the rear rim (3r) of the tubular body (3), is realized in one piece with said lid or cover (13) and is arranged on the lid or cover (13) so as to be substantially coaxial to the rear rim (3r) of the tubular body (3);
the rear circular sealing gasket (10) being encircled and firmly fitted into the gasket-supporting collar (16).
Rotary-drum laundry dryer according to Claim 1, characterized in that said gasket-supporting collar (16) is realized in one piece with said lid or cover (13) via an injection molding process.
Rotary-drum laundry dryer according to Claim 1 or 2, characterized by said lid or cover (13) is fixed to the inner face of the supporting bulkhead (12) in substantially airtight manner.
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized by also comprising an anti-entangling nose (19) which protrudes from the lid or cover (13), extends inside the tubular body (3) and is properly shaped/dimensioned so as to prevent, when the tubular body (3) rotates, the entangling of the damp laundry located into the rotatable drum (3).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that said lid or cover (13) is substantially circular in shape, has an outer diameter greater than that of the rear rim (3r) of the tubular body (3), and is fixed to the supporting bulkhead (12) substantially coaxial to the longitudinal axis (L) of the tubular body.
Rotary-drum laundry dryer according to Claim 5, characterized in that the peripheral border (13a) of the lid or cover (13) is furthermore L-bent upwards so as to form said cylindrical gasket-supporting collar (16).
Rotary-drum laundry dryer according to Claim 5 or 6, characterized in that said lid or cover (13) is substantially dish- or basin-shaped and it is fixed to the inner face of the supporting bulkhead (12) with its concavity directly facing the supporting bulkhead (12), so as to form, together with the gasket-supporting collar (16), a substantially circular-shaped annular seat or groove (10a) which is shaped/dimensioned to house the rear circular sealing gasket (10).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that the supporting bulkhead (12) is provided with a substantially sink-shaped bulge or recess (12a) which is aligned/faced to a rear mouth of the tubular body (3) delimited by said rear rim (3r), projects outwards of the casing (2) and communicates with the hot-air generator (6); the lid or cover (13) being fixed to the supporting bulkhead (12) above said outwards-projecting bulge or recess (12a), and being shaped/dimensioned to cover said outwards-projecting bulge or recess (12a) to form the inner cavity (15) of the rear wall (2b) of the casing (2).
Rotary-drum laundry dryer according to Claim 8, characterized in that the outwards-projecting, sink-shaped bulge or recess (12a) is substantially circular in shape and has an outer diameter lower than that of the rear circular sealing gasket (10) and of the rear rim (3r) of tubular body (3), so as to be located inside the perimeter of the rear rim (3r) of the tubular body (3).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that the lid or cover (13) is firmly fixed to the supporting bulkhead (12) with the interposition of an additional annular sealing gasket (14).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that said lid or cover (13) is firmly fixed to the supporting bulkhead (12) by means of a number of fixing members (17) that engage in sequence the supporting bulkhead (12) and the lid or cover (13).
Rotary-drum laundry dryer according to Claim 11, characterized in that the gasket-supporting collar (16) is provided with a number of anchoring seats (17a) which are spaced along the perimeter of the same collar, and each of which is structured to receive a respective fixing member (17).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that the supporting bulkhead (12) is made of metal material.
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that the hot-air generator (6) comprises a heat-pump assembly (23, 24) structured for continuously cooling and then heating the air circulating inside the rotatable drum (3).
Rotary-drum laundry dryer according to any one of the foregoing claims, characterized in that said substantially cylindrical-shaped, tubular body (3) is structured for resting on a number of idle supporting rollers (8) which are arranged approximately at the two axial ends of the tubular body (3), so as to allow the tubular body (3) to freely rotate about its longitudinal reference axis (L) inside the casing (2).