Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention concerns an automa-t.ic dishwasher Eittecl
with at least one heat sensor suitab:Le to show the temperature
of the operating liquid contained i.n the machine.
As is known, dishwashers are fitted with means of control
and command for the various workiny parts; in particu].ar,
such means are ab:Le to cause -the water let into -the wash tub
to be heated and to show the same's -tem~?erature, e.~. for the
purpose of switching OFF the heat when the water reaches the
temperature as previously set.
In modern dishwashers the means of con-trol and command
are normally made up of electronic devices, and the water
temperature is revealed by a-t least one heat sensor housed in
the machine's wash tub; e.g. in the vicini-ty of the
collection well, in a position in which it is substantially
submerged in the water beiny controlled. The heat sensor is
of the hermetically encapsulated type in order to ensure the
necessary electrical insulation. This makes it relat:ively
expensive. Moreover, the mass o:E the capsule can bri'ng about
delays in the response time of the sensor which, under certain
COllCI:it:i.OllS, Cclll the:re.l.o:l-e p.r.ove to be :Lmp:l^ecise.
In add:ition, since the temperatu:re sensor's electrical
connections to the associ.ated means of the machine's control
and command must be placecl outside the wash tub, the latter
must have a hole allowing the sensor's placement inside it and
such openiny must be hermetically sealed. The temperature
sensor's installation thus proves to be qui.te complex in that
it requires specific processiny arran~ements and the use of a
means to effect a hydraulic seal.
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The intention is tha-t a ~ishwasher be furnished with a
simple and reliable wa-ter-temperature sensor tha-t can be
installed in operating position in a similarly simple and
rapid manner.
In the invention, the characteristics of the attached
claims are deemed to have been achieved in a dishwasher with a
water-temperature sensor that incorporates them.
The characteristics and advantages of the invention will
become more evident from the following description, given
merely as a non-limiting example. Such description makes
reference to the only figure attached, which shows a partial
cross section of a preferred construction form of wash tub as
per the invention.
With reference to the figure, the dishwasher is equipped
mainly with a wash tub (1) whose bottom has a water-collection
well (2), preferably made out of plastic.
In the usual manner, the wel] (2) communicates wlth the
remaining part of the wash tub (1) through a filter ~3) having
a substantially truncated-cone portion (~L) and a substantially
cylindrical central portion (5).
A motorized pump assembly ls i.nstalled i.n the bottom of
the well (2). It can be made substantially as described in
~S-A-~L 799 855. In particular, such pump assembly consists of
a centrifugal circulation pump (6) and a discharge pump (7) of
the centrifugal type. The rotors of` the pumps (6,7) are
splined to the drivesha~t (~) of a reversible electric motor
(9) to be driven alternatively when the shaft (8) rotates in
one or the other direction. In the familiar manner, the
discharye pump (7) is suitable to force to the drain (not
shown) the water suc]ced from the bottom of -the well (2), while
the circulation pump (6) has an axial aspiration section (10)
placed in the vicinity o:E the bottom cf -the well (2), by means
of which it draws water to convey to its own force duct (ll)
duriny the machine's washing cycle. ~ore precisely, the
circulation pump's force duct (11) is suitable to feed at
least one rotor (not shown for the sake of simplicity) placed
above the filter (3) and suitable -to spray the dishes to be
washed. The dishwasher includes, in additlon, at least one
heatinc~ element, or similar (12), to heat the water (which may
have deteryent added) that collects in the well (2). The
element (12) should preferably be installed on the bottom of
the wash tub (1), above the filter (3).
In a familiar manner, the machine's main workiny parts,
such as the motor (9) and the heating element (12), must be
understood to be commanded by a programmed timer (not shown),
preferably o:f electronic type, includiny for examplela
Motorola 680~ or 6805 microprocessor. In par-ticular, a
control and command device (:L3) suitable -to provi.de power a-t
mains (1~) voltaye in a proyrammed manner to the heatincJ
element (12) uncler the control of at least one temperature
sensor (15), is represented schematically in the figure. The
control and command device (13) is suitable for example to
feed the element (12) duri.ny the heat:incJ cycle established by
the timer, in order for the water collected in the well (2) to
reach the temperature as previously set, revealed by the
temperature sensor (15). As a:Lready slated, the timer and the
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control and command device (13) can he o~ any known type. In
any case they are not a part of this invention.
According to one aspect of t.he invention, the sensor (15)
is placed on the outside of the wash tub (1) where it is
placed in heat-exchange relationship with the water contained
in the tub through the same's wall.
More precisely, in the well (2), a part (16) protruding
inward and molded to form a cavi-ty (17) communicating only
with the outside of the well is made, preferably all in one
piece. The sensor (15) is inserted in-to the cavity (17), in
which i-t is preferably immersed in a heat-conducting paste, or
similar, not shown for the sake of simplicity.
The mechanical fasteniny of the sensor (15) can be
ensured by a cable support frame (21) traversed by the
sensor's electric terminals (18). The frame (21) is
pre~erably forced into the cavity (17) of the molded portion
(16) and is fitted with a st..rrup (1~) fastened by a bol-t (20)
to a blind threaded hole (22) made on the outside o~l the well
(2).
In any case, the placement of the sensor (15) outside the
well (2) ensures total hydraulic (and el.ectri.cal in the
preferred case in which the well ~2) is made out of plastic)
isolation/insulation from the water whose temperature it is to
reveal. Advantayeously therefore, the heat sensor (15) does
not require any encapsulatioll, but may be an aspecific
elementary sensor, there~ore reli.able and cheap, such as for
example the Siemens K~Y 6 temperature sensor.
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It appears evident -to a technician in this field that the
molded portion (16) and the threaded hole (22) can easily be
formed during the usual molding cycle of the entire well (2)
and allow sure and rapid assembly of -the temperature sensor
(15) without the need to use anything to effect a hydraulic
seal.
Obviously, the operational precision of the sensor (15)
presupposes that it have a good heat-exchange relationship,
through the wa]ls of the molded ~art (~6), with the water
whose temperature it is to reveal. For the purpose, the
molded part (16) should be made with thin walls (e.g. with
maximum thickness of 1.5 mm), in order not to lead to any
substantial dynamic delay in the temperature sensor's (15)
response times. Moreover, the molded part (16) should
preferably be put in the bottom of the well (2) in an area
adjacent to the circulation pump's (6) intake (10), i.e. in an
area where sufficient wa-ter flow i.s always present duriny the
heating cycle. I
Of course the described clishwasher can unclercJo numerous
modifications without oversteppiny the scope of the invention
as defined in the attached claims.
