[0001] This invention relates to tumble driers.
[0002] It is known to provide heat exchangers to enable moisture to be removed from the
air flow through the drum, a fan re-circulating air through a path which includes
the drum and the heat exchanger. It is also known for such heat exchangers to be removable
from the front of the drier, because the air flow through them picks up fibres from
the load in the drum and from any filters provided, and such heat exchangers therefore
tend to become clogged. Removal enables such heat exchangers to be cleaned. In some
arrangements, one motor is provided to drive the drum and another is provided to drive
the fan. In another arrangement (US-A-3032887), one motor drives both the drum and
the fan for recirculating air. A second fan is provided for blowing air through the
heat exchanger comprising tubes arranged at the front and running from side to side
of the drier, the fan being driven by a pulley and belt. The size of the cabinet of
the tumble drier is dictated by certain standard dimensions, and the packaging of
the various items often causes problems.
[0003] According to the invention, the heat exchanger tubes are arranged substantially at
right angles to the front of the drier, and the second fan is also arranged on a shaft
of the motor, the motor shafts being parallel to the tubes and spaced therefrom in
a direction from side to side of the drier.
[0004] The use of the drum motor for shaft-driving both fans and the arrangement of the
motor and fans side-by-side with the heat exchanger tubes arranged substantially at
right angles to the front of the drier produces a particularly compact arrangement
with a relatively small opening in the front of the drier for withdrawal of the heat
exchanger for cleaning purposes, as well as eliminating the need for a belt and pulley
to drive the second fan.
[0005] A tumble drier constructed in accordance with the invention will now be described
by way of example with reference to the accompanying drawings, in which:-
Figure 1 is a schematic perspective view of the tumble drier;
Figure 2 is a top plan view of the tumble drier, but with components down to and including
the drum not shown;
Figure 3 is a side view of the tumble drier with a duct omitted for clarity;
Figure 4 is a front view of the tumble drier;
Figure 5 is an enlarged view of a fan and housing for re-circulating air flow; and
Figure 6 is a schematic perspective view of the condensate container.
[0006] The tumble drier comprises a rotatable drum 1 housed in a cabinet 2, the drum being
mounted on a bearing 3 at the front of the machine and a bearing (not shown) at the
rear of the machine. A load is inserted into the tub through a door 4. The drum 1
is rotated by a motor 5 by a drive belt 6. The load is dried by means of an air flow
heated by a heating element (not shown) in duct 7, which air flow circulates through
the drum and through a condenser in the form of a heat exchanger indicated generally
by the reference numeral 8 in a closed loop (see arrows 9 to 12). The heat exchanger
is cooled by a flow of atmospheric air (arrows 13, 14). Condensed moisture is collected
in container 15.
[0007] The layout of the motor and fans for producing the air flows will now be described.
The motor 5 has output shafts at each end. As well as driving the drum belt 6, the
forward shaft 16 drives a fan 17 in a housing 18 in order to impel air through the
drum. The rear shaft 19 drives a fan 20 in a housing 21 in order to impel atmospheric
cooling air through the heat exchanger. The co-axially arranged motor and fans lie
laterally with respect to the heat exchanger 8.
[0008] Referring to figure 5, the fan 17 consists of a rotatable fan wheel i.e. a wheel
bearing curved blades 22 which is rotatable in a volute housing i.e. the outer periphery
of the housing is in the shape of a scroll so that the clearance between the fan and
the housing gradually increases towards the outlet 23, which is tangential to the
fan wheel. The inlet is axially into the centre of the fan wheel. Such a fan has a
high efficiency, i.e. a high air throughput, when the fan is rotated in the direction
of the arrow, but a low throughput when the fan is rotated in the opposite direction.
The fan 20 and its housing are identical to the fan 17 and its housing.
[0009] The heat exchanger 8 consists of a number of flat tubes 24 (through which the re-circulating
air passes) which run longitudinally along the heat exchanger. At the front and rear
ends the tubes are set into plastics panels 25, 26, which block the spaces between
the tubes, and top and bottom panel 27, 28 have offset slots in then (the top one
being shown at 38) for feeding the cooling air across the condenser tubes.
[0010] The heat exchanger 38 is housed in a chamber 30, with which the housing 18 communicates
for the inlet to the heat exchanger (arrow 9). The re-circulating air flow is driven
by the fan 17 through the tubes 24 and leaves the rear end 31 of the chamber (arrow
10), and enters the duct 7 which contains the heating element. The now heated re-circulating
air enters the rear of the drum through a slot 32 and, after flowing through the drum,
passes along a tapering duct 33 (arrow 12) and enters the fan housing 17 axially through
an aperture 34. The heated and moist air is driven into the chamber 30 again. The
front panel 35 of the chamber 30 can be opened (and a similar panel on the front of
the cabinet 2 may be opened) in order to enable the heat exchanger 8 to be withdrawn
longitudinally from the cabinet 14. Particles of fibre and of lint filters (not shown)
will be entrained in the re-circulating air flow, and the heat exchanger should be
periodically removed and cleaned to prevent it becoming clogged.
[0011] The cooling of the heat exchanger is effected by the fan 20. Cooling ambient air
(arrow 13) from the atmosphere is drawn axially through inlet 35a into aperture 36
in the fan housing 21 and enters chamber 30 through slot 37 in the underside of the
chamber. The air passes over the heat exchanger tubes 24 and leaves the chamber through
slot 38 (arrow 14), which is offset relative to the slot 37 in order to cause turbulence
in the cooling air flow and therefore promote better heat transfer. The air which
has now been heated re-enters the atmosphere.
[0012] The side-by-side arrangement of the heat exchanger 8 on the one hand and the motor
5 and co-axial fans 17 and 20 on the other hand permits: the use of a single motor
for the drum and two fans; an axial air entry into both fan housings; and accessibility
of the heat exchanger from the front of the machine.
[0013] An electronic circuit is provided for periodically reversing the direction of rotation
of the motor. Instead of providing equal periods of forward and reverse rotation as
hitherto, the motor rotates the drums and fan in a repetitive cycle consisting of
a forward rotation of five minutes and a reverse rotation of half a minute. In this
way, the fans are operating in an efficient manner for around 90% of the time and
in an inefficient manner only for around 10% of the time. Overall the air flow through
the drum is effective for drying even though the air flow is subject to the impedance
created by the condenser and the ducting of the re-circulating loop. Equally, the
short reversal is effective for preventing tangling of the clothes, in the same way
as equal length reversals were hitherto.
[0014] The use of unequal forward and reverse times permits the use of high efficiency fans
but without the need for individual drive motors.
[0015] Referring to figure 3, the moisture from the re-circulating air leaving the drum
condenses and runs from drains 39, 40 to the pump 40a (figure 1) which is powered
by its own electric motor, and which pumps the liquid to a container 15. Referring
to figure 6, the container is withdrawn by the user periodically to empty it and has
means to prevent it being over filled.
[0016] Thus, container 15, when fully inserted, rests on spring-loaded pressure pad 42.
An operating lever 43 pivoted at 44 passes through a slot 45 in support panel 46.
One end rests on the upper surface of the container 15. The other end rests on a further
lever 47 which, when depressed, operates a switch 48 which switches on the pump motor
and the main motor as well.
[0017] When the container 41 becomes filled to a predetermined level, the weight is such
that the pressure pad 42 is depressed by a predetermined amount. In turn, the end
of the lever resting on the container is depressed and the other end raised, so that
the switch 48 operates. The user then withdraws the container and empties it, and
the switch remains in the off position. Only when the empty container has been re-inserted
will the levers set the switch to the position in which the machine can re-start.
[0018] Various modifications may of course be made to the embodiment described without departing
from the scope of the invention. Thus, although the motor 5 is a two pole capacitor
start and run induction motor, instead it could be a relay start motor, or indeed
a four pole motor could be used. Equally, different forward and reverse periods in
the reversing cycle of the motor are possible: thus, the ratio of forward to reverse
for each cylinder could be from 5:1 to 20:1, and the cycle time could be between three
minutes and ten minutes. Also, the points of entry to and exit from the heat exchanger
could be changed. If desired the heat exchanges could be water cooled instead of air
cooled.
1. A tumble drier which comprises a rotatable drum (1), a first fan (17) for producing
an air flow through the drum, a heat exchanger (8) comprising a plurality of tubes
(24) through which air flow through the drum passes in use before being re-circulated
to the drum and which is removable through an opening in the front of the drier, the
first fan being arranged on a shaft (16) of a motor (5) for rotating the drum, a second
fan (20) being provided for passing cooling air from the atmosphere through the heat
exchanger (8), the second fan also being driven by the motor (5), characterised in
that the heat exchanger tubes are arranged substantially at right angles to the front
of the drier, and in that the second fan is also arranged on a shaft of the motor,
the motor shafts being parallel to the tubes and spaced therefrom in a direction from
side to side of the drier.
2. A tumble drier as claimed in claim 1, in which the motor (5) is arranged between the
two fans (17, 20).
3. A tumble drier as claimed in claim 1 or claim 2, in which an inlet (37) for the cooling
air is spaced along the length of the tubes relative to, and beneath, an outlet (38)
for the cooling air, so that the cooling air passes along the length of the tubes
as well as upwardly past the heat exchanger tubes.
1. Taumeltrockner mit einer rotierbaren Trommel (1), einem ersten Gebläse (17) für die
Erzeugung eines Luftstromes durch die Trommel und einem Wärmetauscher (8), welcher
eine Mehrzahl an Röhren beinhaltet, durch die im Betrieb Luft strömt und wieder in
die Trommel zurückgeführt wird und welcher durch eine Öffnung an der Vorderseite des
Trockners entnommen werden kann, wobei das erste Gebläse auf einer Welle (16) eines
Motors (5), de die Trommel antreibt, angeordnet und im zweiten Gebläse (20) vorgesehen
ist für die Versorgung des Wärmetauschers mit Außenluft zu Kühlzwecken, und das ebenfalls
durch den Motor (5) angetrieben wird,
dadurch gekennzeichnet,
daß die Röhren des Wärmetauschers im wesentlichen im rechten Winkel zu der Vorderseite
des Trockners angeordnet sind, und daß das zweite Gebläse ebenfalls auf einer Welle
des Motors angeordnet ist, wobei die Wellen des Motors parallel zu den Röhren verlaufen
und in einer Richtung von einer Seite des Trockners zur anderen beabstandet sind.
2. Taumeltrockner nach Anspruch 1,
dadurch gekennzeichnet,
daß der Motor (5) zwischen den beiden Gebläsen (17, 20) angeordnet ist.
3. Taumeltrockner nach Anspruch 1 oder 2,
dadurch gekennzeichnet,
daß ein Einlaß (37) für die Kühlluft längs der Röhren relativ zum darüberliegenden
Auslaß der Kühlluft so beabstandet ist, daß die Kühlluft sowohl längs der Röhren als
auch nach oben an den Röhren des Wärmetauschers vorbeiströmt.
1. Séchoir à tambour, qui comprend un tambour rotatif (1), un premier ventilateur (17)
destiné à engendrer un flux d'air à travers le tambour, un échangeur de chaleur (8),
comprenant une pluralité de tubes (24) dans lesquels le flux d'air qui traverse le
tambour passe en utilisation avant d'être recyclé vers le tambour, et qui peut être
extrait à travers une ouverture pratiquée dans la face avant du séchoir, le premier
ventilateur étant agencé sur un arbre (16) d'un moteur (5) servant à raire tourner
le tambour, un second ventilateur (20) étant prévu pour faire passer de l'air de refroidissement
pris sur l'atmosphère à travers l'échangeur de chaleur (8), le second ventilateur
étant aussi entraîné par le moteur (5), caractérisé en ce que les tubes de l'échangeur
de chaleur sont disposés sensiblement perpendiculairement à la face avant du séchoir
et en ce que le second ventilateur est lui aussi monté sur un arbre du moteur, les
arbres du moteur étant parallèles aux tubes et espacés de ces tubes dans le sens allant
d'un côté à l'autre du séchoir.
2. Séchoir à tambour selon la revendication 1, dans lequel le moteur (5) est disposé
entre les deux ventilateurs (17, 20).
3. Séchoir à tambour selon la revendication 1 ou la revendication 2, dans lequel une
entrée (37) pour l'air de refroidissement est espacée, selon la longueur des tubes,
par rapport à une sortie (38) de l'air de refroidissement, et placée au-dessous de
cette sortie, de sorte que l'air de refroidissement s'écoule selon la longueur des
tubes aussi bien que de bas en haut au droit des tubes de l'échangeur.