DOMESTIC CLOTHES DRYER AND METHOD FOR DRIVING SUCH DRYERS

Abstract

A domestic clothes dryer includes a rotating drum that defines a drying chamber, an air inlet upstream the drum, and a lifter coupled to the drum. The lifter is in communication with the air inlet for distributing air inside the drum through a plurality of openings. The air inlet includes a shaped air plenum chamber facing a lower portion of a rear perforated wall of the drum and capable of delivering air to said lifter and/or directly to the drum through the rear perforated wall.

Claims

1. A clothes dryer comprising: a rotating drum having a rear perforated wall and a side wall, wherein the rear perforated wall and the side wall at least partially define a drying chamber; a lifter extending over at least a portion of a first surface of the rear perforated wall, the lifter extending over at least a portion of the side wall, the lifter having a base portion coupled to the rear perforated wall to define an inner chamber therebetween, the lifter having a plurality of openings to convey air from inside the lifter into the rotating drum; and a shaped air plenum chamber that delivers air through the rear perforated wall into the base portion of the lifter when the lifter is in a first pre-determined position relative to the shaped air plenum chamber, wherein the shaped air plenum chamber delivers air through the rear perforated wall directly into the rotating drum in a region that is circumferentially adjacent to the base portion of the lifter when the lifter is in the first pre-determined position relative to the shaped air plenum chamber.

2. The clothes dryer of claim 1, wherein the base portion of the lifter defines a first surface area through which air is received from the rear perforated wall.

3. The clothes dryer of claim 2, wherein the shaped air plenum chamber comprises a second surface area through which air is delivered to the rear perforated wall, and wherein the second surface area is greater than the first surface area.

4. The clothes dryer of claim 1, wherein the shaped air plenum chamber delivers air through the rear perforated wall directly into the rotating drum when the lifter is in a second pre-determined position relative to the shaped air plenum chamber.

5. The clothes dryer of claim 1, wherein the shaped air plenum faces a second surface of the rear perforated wall of the rotating drum.

6. The clothes dryer of claim 5, wherein the first surface of the rear perforated wall and the second surface of the rear perforated wall are on opposing sides of the rear perforated wall.

7. The clothes dryer of claim 1, wherein the shaped air plenum chamber faces a lower portion of the rear perforated wall.

8. The clothes dryer of claim 7, wherein an upper edge of the shaped air plenum chamber is positioned below a center of the drying chamber.

9. The clothes dryer of claim 1, wherein the side wall extends from the rear perforated wall.

10. The clothes dryer of claim 9, wherein the side wall defines a circumference of the rotating drum.

11. The clothes dryer of claim 1, wherein the drying chamber is further defined by a door that is movable between an open position and a closed position.

12. The clothes dryer of claim 1, further comprising: an air inlet upstream of the rotating drum, wherein air is delivered from the air inlet to the shaped air plenum chamber.

13. The clothes dryer of claim 1, wherein the base portion has a triangular sector shape.

14. A clothes dryer comprising: a rotating drum having a rear perforated wall and a side wall, wherein the side wall extends from the rear perforated wall, wherein the side wall defines a circumference of the rotating drum, and wherein the rear perforated wall and the side wall at least partially define a drying chamber; a lifter extending over at least a portion of a first surface of the rear perforated wall, the lifter extending over at least a portion of the side wall, the lifter having a base portion coupled to the rear perforated wall to define an inner chamber therebetween, the lifter having a plurality of openings to convey air from inside the lifter into the rotating drum, wherein the base portion of the lifter defines a first surface area through which air is received from the rear perforated wall; and a shaped air plenum chamber that faces a second surface of the rear perforated wall, wherein the shaped air plenum chamber comprises a second surface area through which air is delivered to the rear perforated wall, wherein the second surface area is greater than the first surface area, wherein the shaped air plenum chamber delivers air through the rear perforated wall into the base portion of the lifter when the lifter is in a first pre-determined position relative to the shaped air plenum chamber, and wherein the shaped air plenum chamber delivers air through the rear perforated wall directly into the rotating drum in a region that is circumferentially adjacent to the base portion of the lifter when the lifter is in the first pre-determined position relative to the shaped air plenum chamber.

15. The clothes dryer of claim 14, wherein the shaped air plenum chamber delivers air through the rear perforated wall directly into the rotating drum when the lifter is in a second pre-determined position relative to the shaped air plenum chamber.

16. The clothes dryer of claim 14, wherein the first surface of the rear perforated wall and the second surface of the rear perforated wall are on opposing sides of the rear perforated wall.

17. The clothes dryer of claim 14, wherein the base portion has a triangular sector shape.

18. The clothes dryer of claim 14, wherein the shaped air plenum chamber faces a lower portion of the rear perforated wall.

19. The clothes dryer of claim 18, wherein an upper edge of the shaped air plenum chamber is positioned below a center of the drying chamber.

20. The clothes dryer of claim 14, further comprising: an air inlet upstream of the rotating drum, wherein air is delivered from the air inlet to the shaped air plenum chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Further advantages and features of this disclosure will be clear from the following detailed description, with reference to the attached drawings, in which:

[0010] FIG. 1 is an isometric view of an example clothes tumble dryer;

[0011] FIG. 2 is an isometric enlarged view of the inside of the drum of FIG. 1;

[0012] FIG. 3 is an isometric view of the rear of the drum of FIGS. 1 and 2;

[0013] FIG. 4 is a partial cross-sectional view of a detail of FIG. 2;

[0014] FIG. 5 is a front view of the perforated rear wall of the drum where the shape of the distributor is shown in solid and dotted line; and

[0015] FIG. 6 is a schematic view of how a clothes dryer according to this disclosure works.

DETAILED DESCRIPTION

[0016] With reference to FIG. 1, an example tumble dryer 10 includes a cabinet 12 having an upper wall 12a, a front wall 12b provided with a hingedly mounted door 14, side walls 12c and a rear wall 12d. Inside the cabinet 12 a rotating drum 16 is mounted which is actuated by an electric motor (not shown) and which defines a drying chamber 17. The drum 16 includes at least one lifter 18 having a plurality of holes 20 for air passage. The lifter 18 may be hollow. The lifter 18 includes a rear base portion 18a covers a portion of a rear perforated wall 16a of the drum in order to convey air entering through the perforated wall 17a towards the holes 20 of the lifter 18. The rear base portion 18a may have a triangular or circular sector shape. The base portion 18a defines with the facing portion of the rear wall 16a of the drum 16 a sort of inner chamber 19 (see FIG. 4) which covers an arc ranging preferably from 60° to 100° and which communicates with the portion of the lifter 18 fixed to the side wall of the drum 16. The clothes dryer 10 may also have a dispensing system for dispensing treating chemistries into the drum 16, and including a reservoir 22 that is closed by a cover 24. The clothes dryer 10 is also provided with a controller 26 that may receive input from a user through a user interface 28 for selecting a cycle of operation.

[0017] The clothes dryer 10 also includes an air inlet channel 30 (see FIG. 6) and an outlet channel 32, a heating system (not shown) that heats air entering the drum (e.g. by means of resistors, heat exchangers, etc.), and a blower (not shown) that makes air flowing across the drum 16.

[0018] The drum outlet 32, where a removable filter 33 for removing fluff or lint is placed, can be eventually connected to the drum inlet 30 thus realizing a closed loop system in which heat exchangers, resistors, heat pump, etc. control the condensation and heating process. As an alternative the drum outlet 32 can be connected to an air vent.

[0019] The lifter 18 functions not only to increase the heat exchange efficiency between air and clothes and improve the evenness of the drying result by means of clothes redistribution during the whole cycle, but also to improved the efficiency of hot air distribution.

[0020] A common drawback of known dryers is that when the load size increases to almost fill the drum volume, the efficiency of the lifter in redistributing the load within the drum is decreased thus leading to the risk of damaging the clothes that are positioned in the rear end of the dryer (where temperatures are higher) and reducing the evenness of drying results.

[0021] With a lifter design that allows not only the hot air to flow through the lifter 18 but also by means of a distribution of air through the lifter 18 only during a certain degree of rotation of the drum 16, the temperature gradient in the drum 16 is reduced and the evenness of drying is increased, reducing also the risk of clothes damaging.

[0022] The above controlled distribution is carried out by means of a shaped fixed distributor 34 which forms an air inlet plenum chamber upstream of the drum 16. The shape of the distributor 34 (FIG. 5) does not necessarily correspond to the circular sector shape of the base portion 18a of the lifter 18, but need not extend higher than the lower half of the drum 16. In FIG. 5, two shapes are shown (in dotted and solid lines) which have worked well in tests carried out by the applicants. Such shapes maximize the air flow either through the lifter 18 (when this latter is in the lower positions during rotation) and through clothes adjacent the lifter.

[0023] In other examples, the enhanced lifter design can be combined with a dedicated cycle design, able to stop tumbling when the lifter 18 is located in a position that minimizes the temperature gradient. This approach can furthermore increase the above mentioned advantages and can provide also energy saving benefits due to reduced motor usage. One or more lifters of the type disclosed above can also be used together with one or more typical lifters that do not match the above description. Due to the fact that the lifter 18 is physically connected to the drum 16, during tumbling it changes its position with respect to the air inlet 34 thus leading to a variable air mass flow rate in the lifter 18 and in the drum 16. This is clearly shown in FIG. 6 where arrows A show the air flow through the lifter 18 (when this latter is placed in the lower position inside the drum 16), and arrows B show the air flow through the rear wall 16a of the drum 16 when the lifter 18 is in a position not matching the air distributor 34. This alternating air flow path in the drum 16 creates the conditions for a variable heat flux as well that improves the evenness of drying the fabric care.

[0024] The examples disclosed herein can improve significantly also the drying and fabric care performances with delicate cycles. As described above, aiming to reduce the mechanical action on this type of loads, the tumbling is often reduced or even avoided; this solution has the negative result of increasing the temperature gradient thus leading to the already discussed drawbacks. If the proposed lifter design is used, the machine can be designed to stop tumbling (for the whole cycle or only for part of it, also e.g., using a PWM approach) in a way that the air can flow through the lifter 18 to provide a means to optimize heat flux for these type of loads using appropriate design of the lifter. In some examples, the drum 16 is in a position where the lifter 18 lays on the bottom of the drum 16, thus having the clothes laying on it. The method used to stop the drum 16 in the correct position is well known in the art and it can be easily transferred from the known solutions for top loader washer for having the door in upwards location to facilitate loading and unloading of the drum.

[0025] Moreover, since air can flow through the lifter 18, the latter can be designed to host a cartridge containing a fragrance or some other chemical additives to improve quality of drying that can be released in the drum 16.

[0026] In some examples, the lifter 18 is used with a drum 16 having an air inlet and outlet port on opposite sides thus enabling fine optimization of heat fluxes. Nevertheless the examples disclosed herein can be applied to those drums in which inlet and outlet air connections are located on the same side (with a dedicated air collector similar to air distributor 34). In these examples the lifter 18 can be used to convey hot inlet air towards the opposite side of the drum 16, therefore improving significantly the heat flux distribution in the longitudinal direction.

[0027] FIG. 4 shows a detail of the air distributor 34 which is made preferably by a shaped metal or plastic sheet 35. In order to increase the efficiency, a sealing means (not shown) can be interposed between the edge of the shaped sheet 35 forming the distributor 34 and the rear wall 16a of the drum 16.