FIELD OF THE INVENTION
The present invention concerns a heating device such as
a fireplace, a heater or similar, of the type suitable to be fed with at least two
different types of fuel, such as for example pellets and wood, into which the comburent
air is introduced into a combustion chamber only due to the natural drawing force.
The device according to the invention comprises a system
to regulate and divide the flow, in order to introduce air into the combustion chamber
in quantities functional to the different combustion requirements of the different
fuels and also to the different quantities of fuel loaded.
BACKGROUND OF THE INVENTION
The state of the art includes fireplaces or heaters which
can function alternately and/or conjointly with two types of fuel of different types,
for example with pellets, that is, chips of pressed wood residue, and with wood.
This solution is particularly appreciated since it is possible
to automate the feed with pellets by means of timed loading devices, which considerably
increases the operating autonomy of the heating device and reduces the need for
the user to intervene.
Conventional heating devices comprise a combustion chamber
where the means to contain the two fuels are arranged, normally consisting of braziers
and/or supporting grills.
Comburent air is introduced into the combustion chamber
in order to actuate and maintain combustion.
Conventional devices provide to use at least a fan, which
can be driven and powered in regulatable fashion, and is actuated at least when
the combustion uses pellets. In fact, pellets require a greater quantity of comburent
air with respect to wood, and above all they require a variation in the delivery
of air according to the quantity of pellets loaded, which is normally variable during
Using a fan entails a first disadvantage in that, in the
event of a sudden electricity failure, the comburent air needed for optimum combustion
suddenly fails; this consequently causes an excess of unburnt particles to be emitted,
which are dangerous for the environment. Moreover, the presence of the fan entails
an increase in the costs and consumption of the device. Furthermore, the regulation
of the fan may be imprecise and not correctly adapted to the loading dynamics of
EP-A-985.883 and EP-A-1.134.497 disclose heating appliances
able to be fed with two different kind of fuels.
US-A-4,387,700 discloses a stove having an automatic device
for reduction of the flow to its combustion chamber.
This document shows the features as defined in the preamble
of claim 1.
These documents do not disclose a heating device able to
vary the supply of the air sent to the combustion chamber according to the kind
of fuel to use.
The present Applicant has devised and embodied this invention
to overcome the shortcomings of the state of the art and to obtain further advantages.
SUMMARY OF THE INVENTION
The present invention is set forth and characterized essentially
in the main claim, while the dependent claims describe other characteristics of
The purpose of the invention is to achieve a heating device
such as a fireplace, a heater or similar, of the type with at least double fuel,
such as for example pellets and wood, in which the comburent air is introduced into
a combustion chamber due only to the natural drawing force and in regulatable fashion
as the type of fuel used and the quantity of fuel loaded vary.
In accordance with this purpose a heating device of the
type indicated above comprises at least a combustion chamber in which means to support
and contain a first and second fuel are arranged.
According to a characteristic of the invention, the device
comprises means to regulate and divide the introduction of comburent air, cooperating
with at least an inlet aperture; the means allow the air to be introduced in regulatable
quantities into the combustion chamber due to the natural drawing force alone.
The regulation means are able to selectively send a variable
and controlled quantity of comburent air towards the first fuel or towards the second
fuel. The regulation means comprise means to divide the flow able to be selectively
located in pre-determined positions in order to close the at least one inlet aperture
for the comburent air into the combustion chamber in a variable, but calibrated
and controllable fashion.
In one embodiment of the invention, at least one position
of the flow divisor means is adopted when there is a first fuel present, and at
least a second position, different from the first, is adopted when there is a second
In a preferential embodiment, said at least one aperture
comprises a first and second aperture made on a front wall of the frame of the heating
device and communicates with the combustion chamber so as to selectively convey
the air towards the first and/or second fuel. In this embodiment, the flow divisor
means comprise a movable shutter able to be arranged in a plurality of pre-determined
positions, variable with respect to said inlet apertures, to vary the delivery of
comburent air introduced into the combustion chamber.
The shutter is associated with actuation means, of a manual
type such as a lever, a knob or similar, by which a user, actuating them from outside,
can move the shutter to a pre-determined position.
The heating device according to the invention also comprises
means for the automatic loading of the first fuel into the containing means.
The invention provides that a control unit receives input
signals relating to the position of the divisor means and automatically conditions
the drive of said automatic loading means according to the delivery of air introduced.
In another embodiment, it is the quantity of fuel introduced which automatically
conditions the position of the flow divisor means.
According to another variant, the device comprises temperature
sensor means, able to send relative signals to said control unit in order to drive
the flow divisor means in relation to the temperature detected, for example, in
the combustion chamber and/or in the fume discharge conduit.
According to another variant, the device comprises means
to analyze the fumes which send relative signals to the control unit to drive the
flow divisor means in relation to the higher or lower content of unburnt substances
in the discharge fumes.
According to a further variant, the device comprises optical
sensor means associated to the combustion chamber and oriented at least towards
the flame. The optical sensor means are able to detect at least the presence or
not of the flame, and one or more feature of the flame such as its height, its prevailing
colour, its prevailing contour, the luminosity emitted or other, and to send some
input signals to the control unit according to this detection. On the basis of the
optical detection of some features of the flame, the control unit is arranged to
drive the flow divisor means so as to vary the amount of air introduced in the combustion
chamber; for example, if the optical means detect that the flame is smaller than
a pre-set value, or its luminosity is lesser than a defined value, the control unit
will drive the flow divisor means so as, for example, to increase the amount of
the air to the combustion chamber and restore the correct conditions of combustion
of the flame.
With the device according to the invention it is possible
to regulate - manually, from outside, and without using a regulatable delivery fan
- the introduction of comburent air into a combustion chamber both according to
the type of fuel used, and also the quantity of fuel present, and also the quantity
of heat desired.
Moreover, the regulation of the flow can be automated by
means of a driven actuator and hence correlated both to the quantity of fuel automatically
introduced and also to the temperature reached and also to the composition of the
fumes and further to the features of the flame burning in the combustion chamber.
Another advantage of the present invention is that, since
the device functions with a natural drawing force of the comburent air, in the event
of a sudden black-out, it guarantees that combustion is maintained, without causing
dangerous emissions into the environment.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other advantages of the present invention will
be apparent from the following description of a preferential form of embodiment,
given as a non-restrictive example, with reference to the attached drawings wherein:
DETAILED DESCRIPTION OF A PREFERENTIAL EMBODIMENT
- fig. 1 is a front view of the heating device according to the present invention;
- fig. 2 is a lateral section of the device in fig. 1;
- figs. 3 to 7 show the different operating positions which a flow regulation
means of the device in fig. 1 can assume;
- fig. 8 is a front view of a flow regulation means from figs. 3-7.
With reference to figs. 1 and 2, a heating device according
to the invention is represented by a heater 10 of the multiple feed type, fed by
pellets 11 and wood (not shown in the drawings), and consists of a frame comprising
a box-like structure 12, inside which a combustion chamber 14 is made.
In the upper zone of the box-like structure 12 there is
a container 16 for the pellets 11 connected to a programmable feed member consisting
of a screw, not shown in the drawings, driven by a motor-reduction unit 20 and provided
with a timer unit 21. By means of the screw the pellet 11 is taken from the container
16 and discharged, through a feed conduit 18, into a brazier 15 arranged in the
combustion chamber 14.
The box-like structure 12 comprises a front wall 19 in
the lower zone of which there are apertures 22 and 24 communicating with the outside
and with the combustion chamber 14; the air is conveyed through the apertures 22
and 24 for the combustion of the wood and pellets 11.
The size of the first 22 and the second aperture 24 is
designed so that an optimized flow of comburent air can be sent for the combustion
respectively of the wood and pellets 11. To be more exact, the first aperture 22
has a size designed for an optimum combustion when functioning with wood, while
the second aperture 24, which can be shuttered as will be described hereafter, is
designed for an optimum combustion when functioning with pellets 11.
The brazier 15 has through holes 15b on the bottom to allow
the air to pass and the ash to be removed. The comburent air, both for combustion
of pellets 11 and for combustion of wood, is introduced thanks to the natural drawing
force, due to the depression created inside the combustion chamber 14 after the
combustion fumes have been discharged through an outlet conduit 17.
The heater 10 also comprises means to divide the flow of
comburent air (figs. 3 to 8), consisting of a shutter 30 sliding in cooperation
with the two apertures 22 and 24. The shutter 30 is associated with a drive lever
26 inserted in a front grill 29 and connected to the shutter 30 by an arm 27. In
the shutter 30 there is also a first window 31a and a second window 31b, of a size
mating respectively with the first aperture 22 and the second aperture 24. The shutter
30 can slide in front of or behind the inlet apertures 22 and 24, along a pair of
guides 32 (figs. 2 and 8), arranged opposite each other respectively above and below
the apertures 22 and 24.
The lever 26 can be selectively moved to a plurality of
pre-determined positions A, B, C, D and E, which each correspond to a different
closed condition of the apertures 22 and 24 for the introduction of comburent air
with variable delivery. In this case, the position of the drive lever 26 can be
detected by a sensor 41 associated with a regulation device 40 which, according
to the delivery of air introduced, conditions the drive of the timer unit 21 of
the motor-reduction unit 20, to automatically vary the speed and loading times of
the pellet 11 into the combustion chamber 14, according to the quantity of air introduced.
The heating device according to the invention functions
as follows. In the examples shown here the shutter 30 slides in front of the inlet
apertures 22 and 24, but it is completely analogous and equivalent if the shutter
30 slides behind said apertures 22 and 24.
When the lever 26 is in a first position A, the shutter
30 is completely displaced to the right (fig. 3) and completely closes the second
aperture 24, while the first window 31a coincides with the first aperture 22, to
allow the comburent air to be introduced into the combustion chamber 14. This position
is adopted when the device 10 is functioning mainly with wood, and the air introduced
only through the aperture 22 corresponds to the quantity needed to obtain optimum
By moving the regulation lever 26 completely to the left
to position B, as shown in fig. 4, the shutter 30 closes the first aperture 22,
while the second window 31b is arranged completely in correspondence with the second
aperture 24, so as to obtain a maximum flow of comburent air towards the brazier
15 containing the pellets 11. This position, which determines the introduction of
air only through the second aperture 24, is actuated when the device 10 is functioning
mainly with pellets 11.
The sensor 41 detects the position B of the lever 26, corresponding
to the maximum flow of comburent air, and conditions the speed of the screw to load
the pellets 11 into the brazier 15 in a quantity correlated and proportional to
the flow of air, in order to optimize the combustion conditions.
On the contrary, by positioning the regulation lever in
the intermediate positions, respectively C and D, the shutter 30 closes about 1/3
(fig. 5) and 2/3 (fig. 6) of the second aperture 24 to obtain lesser quantities
of comburent air introduced to the brazier 15.
In correspondence with the positions C and D, the sensor
41 also detects the position of the lever 26 and, by means of the device 40, sends
a command signal to regulate the speed of the screw in order to load a quantity
of pellets 11 which is correlated and proportional to the flow of air introduced
into the combustion chamber 14.
On the contrary, by moving the shutter 30 into the position
E, both the aperture 22 and the aperture 24 are partly opened. In this position
E the heater 10 is regulated for the simultaneous combustion of wood and pellets
The heating device 10 comprises, in an upper zone of the
combustion chamber 14, a plurality of holes 51 to introduce a flow of air, which
achieves the so-called secondary combustion of the substances which have not been
burnt during primary combustion. According to a variant of the invention, a door
50 is mechanically connected, by means of an articulated arm (not shown here), directly
to the lever 26, to selectively close said holes 51.
When the regulation lever 26 is in position A, or E, corresponding
to the introduction of air for the combustion of wood, the door 50 is opened to
introduce air to the upper part of the combustion chamber 14 and to achieve secondary
combustion. On the contrary, when the drive lever 26 is in any of positions B, C
or D, wherein combustion is regulated for burning pellets 11, the door 50 is closed
so as to prevent the circulation of air in the upper part of the combustion chamber
14 and to concentrate said circulation on the level of the brazier 15, to optimize
the post-combustion of the pellets 11.
In a variant not shown here, for example, the device may
comprise at least a temperature sensor and/or a sensor to analyse the composition
of the fumes and/or an optical sensor to detect at least a feature of the flame
burning in the combustion chamber. The above sensors are connected to a processing
unit which is able, from the signals sent by the sensors, to obtain information
about the characteristic of the combustion and to drive automatically the movement
of the shutter 30 to regulate accordingly the amount of the air introduced in the
combustion chamber 14.