U.S. patent application number 10/570858 was filed with the patent office on 2006-12-28 for system for controlling the delivery of a fuel gas to a burner apparatus.
Invention is credited to Massimo Giacomelli.
Application Number | 20060292505 10/570858 |
Document ID | / |
Family ID | 34259991 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060292505 |
Kind Code |
A1 |
Giacomelli; Massimo |
December 28, 2006 |
System for controlling the delivery of a fuel gas to a burner
apparatus
Abstract
A system for controlling the delivery of a fuel gas to a burner
apparatus includes a gas-delivery duct extending between an inlet
opening and an outlet opening, a pressure-regulator device
including a servo-valve in the duct, having a closure member with
diaphragm control, the diaphragm being subjected, on one side, to
the pressure regulated by the pressure-regulator device and, on the
other side, to a calibration pressure established in a calibration
chamber of the regulator device, as well as a calibration spring
provided in the calibration chamber and acting on the diaphragm.
The system also includes a delivery-pressure modulator unit
including a modulation valve with a valve seat disposed in the duct
downstream of the pressure-regulator device and cooperating with a
respective closure member operatively connected to an actuator
device arranged for the modulation control of the delivery
pressure, as well as a flow communication device between the
calibration chamber of the pressure-regulator device and the
modulator unit, for bringing into the calibration chamber a
pressure signal that is correlated proportionally with the
gas-delivery pressure so that the pressure regulated by the
pressure-regulator device is in turn correlated with the pressure
signal.
Inventors: |
Giacomelli; Massimo;
(Mirano, IT) |
Correspondence
Address: |
RATNERPRESTIA
P O BOX 980
VALLEY FORGE
PA
19482-0980
US
|
Family ID: |
34259991 |
Appl. No.: |
10/570858 |
Filed: |
September 8, 2003 |
PCT Filed: |
September 8, 2003 |
PCT NO: |
PCT/IT03/00533 |
371 Date: |
March 7, 2006 |
Current U.S.
Class: |
431/12 |
Current CPC
Class: |
F23N 1/007 20130101;
F23N 2235/20 20200101; F23N 2225/06 20200101; F23N 2235/16
20200101; F23N 1/022 20130101; F23N 2235/18 20200101; F23N 1/005
20130101 |
Class at
Publication: |
431/012 |
International
Class: |
F23N 1/02 20060101
F23N001/02 |
Claims
1. A system for controlling the delivery of a fuel gas to a burner
apparatus comprising: a gas-delivery duct extending between an
inlet opening and an outlet opening, a pressure-regulator device
including a servo-valve in the duct, having a closure member with
diaphragm control, the diaphragm being subjected, on one side, to
the pressure regulated by the pressure-regulator device and, on the
other side, to a calibration pressure established in a calibration
chamber of the pressure-regulator device, a calibration spring
being provided in the calibration chamber and acting on the
diaphragms, a delivery-pressure modulator unit including a
modulation valve with a valve seat disposed in the duct downstream
of the pressure-regulator device and cooperating with a respective
closure member operatively connected to actuator means arranged for
the modulation control of the delivery pressure, and a flow
communication means between the calibration chamber of the
pressure-regulator device and the modulator unit, for bringing into
the calibration chamber a pressure signal that is correlated
proportionally with the gas-delivery pressure so that the pressure
regulated by the pressure-regulator device is in turn correlated
with the said pressure signal.
2. The system according to claim 1 in which the calibration chamber
is in flow communication with the delivery duct downstream of the
modulator unit by means of a connecting duct, and the pressure
signal corresponds to the gas-delivery pressure obtained by means
of the modulation valve.
3. The system according to claim 1 in which the pressure signal
brought to the calibration chamber of the pressure-regulator device
is indicative of the air-output pressure of a fan associated with
an air-gas mixer in which the output air-flow of the fan is mixed
with the gas-flow delivered by means of the modulation unit at the
delivery pressure.
4. The system according to claim 1 in which the modulation valve is
of a proportional type with a finite number of modulation
levels.
5. The system according to claim 4 in which the actuator means
associated with the closure member of the modulation valve comprise
a control rod the axial movement of which relative to the
corresponding valve seat is controlled by drive means of the
stepping type.
6. The system according to claim 5 in which the modulator unit
comprises drive transmission means suitable for converting the
rotary movement of the drive means into a translational movement of
the operating rod of the closure member of the modulation
valve.
7. A system according to claim 3 in which the flow communication
means comprise a connecting duct between the calibration chamber of
the pressure-regulator device and a casing portion of the fan which
casing portion is defined in the region of the outlet of the fan,
upstream of the air-gas mixing region of the air-gas mixer.
8. The system according to claim 3 in which the fan is of a
modulating type and its output pressure can be modulated
selectively between a minimum and a maximum pressure value.
9. The system according to claim 7 comprising a differential
pressure sensor provided with detection terminals which are
arranged, respectively, in said connecting duct and in a section of
the gas-delivery duct upstream of the air-gas mixing region of the
air-gas mixer.
10. The system according to claim 9 comprising electronic board
control means arranged to process, in dependence on the pressure
signal detected by said differential pressure sensory, a control
signal for controlling said actuator means so that the delivery
pressure is modulated in order to keep the pressure differential at
a suitable value such as to ensure that the ratio between the air
flow-rate and the gas flow-rate remains constant.
11. The system according to claim 2 in which the modulation valve
is of a proportional type with a finite number of modulation
levels.
12. The system according to claim 3 in which the modulation valve
is of a proportional type with a finite number of modulation
levels.
13. The system according to claim 7 in which the fan is of the
modulating type and its output pressure can be modulated
selectively between a minimum and a maximum pressure valve.
Description
[0001] This application is a U.S. National Phase Application of PCT
International Application PCT/IT2003/000533.
TECHNICAL FIELD
[0002] The present invention relates to a system for controlling
the delivery of a fuel gas to a burner apparatus.
TECHNOLOGICAL BACKGROUND
[0003] The invention relates particularly to the field of systems
for controlling the delivery of gas to burners of heating apparatus
in general, the flame of which is intended for the direct heating
of the environment rather than of an intermediate fluid circulating
in a system with a boiler.
[0004] Apparatus of this type, like all systems using a gas burner,
usually has a system for controlling the delivery of the gas-flow
to the burner so as to regulate its delivery pressure and/or the
flow-rate of gas delivered, in controlled manner. These systems are
therefore typically directed towards a multifunctional control of
the gas-flow delivered to the burner and at the same time have to
ensure the functions of regulation and safety shutoff of the
gas-way in addition to that of modulation of the pressure (or of
the flow-rate delivered) in relation to predetermined
parameters.
[0005] It is known in this field to provide systems which have a
pressure regulator for keeping the pressure downstream of the
regulator constant irrespective of the gas-supply pressure, and a
modulator unit with a delivery-pressure modulation valve, disposed
downstream of the regulator. In this case, the modulation valve
operates between a pressure upstream of the modulator, which is
equal to the pressure regulated by the pressure regulator, and a
pressure downstream of the modulator, which is equal to the
delivery pressure of the gas-flow towards the burner.
[0006] In systems of the above-mentioned type, for a preselected
calibration, the pressure regulated by the pressure regulator is
substantially constant as the gas-delivery pressure varies, thus
defining a predetermined degree of resolution of the modulation,
"resolution" being understood as the index of the so-called
"discretization" (i.e. rendering discrete) of the delivery pressure
that can be achieved by a modulation valve with a finite number of
levels, such as the valves which are typically used in these
applications.
BRIEF DESCRIPTION OF THE INVENTION
[0007] A main object of the present invention is to provide a
system for controlling the delivery of a fuel gas to a burner
apparatus in which, for given parameters of the system, the
resolution is improved, with an amplification of the level of
"discretization" of the delivery pressure such as to permit a more
precise and reliable modulation of the pressure (flow-rate).
[0008] The foregoing and other objects are achieved by the
invention by means of a system for controlling the delivery of a
fuel gas to a burner apparatus. The system includes a gas-delivery
duct extending between an inlet opening and an outlet opening, and
a pressure-regulator device including a servo-valve in the duct,
having a closure member with a diaphragm control. The diaphragm
being subjected, on one side, to the pressure regulated by the
pressure-regulator device and, on the other side, to a calibration
pressure established in a calibration chamber of the
pressure-regulator device. A calibration spring is provided in the
calibration chamber and acts on the diaphragm. The system also
includes a delivery-pressure modulator unit including a modulation
valve with a valve seat disposed in the duct downstream of the
pressure-regulator device and cooperating with a respective closure
member operatively connected to actuator means arranged for the
modulation control of the delivery pressure, and a flow
communication means between the calibration chamber of the
pressure-regulator device and the modulator unit, for bringing into
the calibration chamber a pressure signal that is correlated
proportionally with the gas-delivery pressure so that the pressure
regulated by the pressure-regulator device is in turn correlated
with the pressure signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The characteristics and the advantages of the invention will
become clearer from the following detailed description of two
preferred embodiments thereof which are described by way of a
non-limiting example with reference to the appended drawings, in
which:
[0010] FIG. 1 is a schematic view showing a first embodiment of the
control system according to the invention, in longitudinal
section,
[0011] FIG. 2 is a view corresponding to FIG. 1 of a second
embodiment of the system according to the invention, and
[0012] FIG. 3 is a graph representative of the system according to
the invention.
PREFERRED METHOD OF IMPLEMENTING THE INVENTION
[0013] In the above-noted drawings, a main duct for the transfer of
fuel gas (hereinafter referred to simply as gas) from a delivery
element to a burner apparatus (neither of which is shown) is
indicated by the numeral 1. The duct 1 extends between a gas-inlet
opening 2 and an opening 3 for the outlet of the gas towards the
burner. The supply pressure and the delivery pressure of the gas
are indicated Pi and Pu, respectively.
[0014] The body of a pressure-regulator device, generally indicated
4, is formed in the duct 1; the device 4 includes a servo-valve
defining a valve seat 5 cooperating with a closure member, shown
schematically at 6, the control rod 6a of which is connected
rigidly to a diaphragm 7 for operating the rod 6a.
[0015] The diaphragm 7 is subjected, on one side, to the pressure
which is regulated by the regulator device 4 and which is indicated
Pr and, on the other side, to a pressure established in a
calibration chamber 8 of the regulator. As will be described in
detail below, the pressure acting on the diaphragm in the chamber
is defined partly by the resilient load exerted by a calibration
spring 9 housed in the chamber 8. The resilient load acting on the
diaphragm 7 is adjustable by means of an adjustment screw 10. The
pressure exerted on the diaphragm 7 by the spring 9 is referred to
below as Pt.
[0016] The system according to the invention also has a unit,
generally indicated 11, for modulating the delivery pressure Pu;
the unit 11 is provided in the duct 1, downstream of the pressure
regulator 4. The modulator unit comprises a modulation valve with a
valve seat 12 cooperating with a closure member 13 which is
operatively connected to actuator means for the modulation control
of the delivery pressure Pu.
[0017] The closure member 13 has a control rod 13a the axial
movement of which relative to the valve seat 12 is brought about by
drive means, shown schematically and indicated as 14[,] (for
example, of the stepping type), in a manner such that the
regulation of the closure member 13 is of the proportional type
with a finite number of modulation levels. Transmission means are
provided between the drive means 14 and the rod 13a and comprise,
for example, a male-and-female screw coupling arranged for
converting the rotary movement of the drive means into the
translational movement of the rod.
[0018] The above-mentioned modulation valve may be of the type
described in the Applicant's Italian patent application No. PD
2001A000240, the description of which is therefore included herein
by reference for any further characteristic not expressly
mentioned.
[0019] An electronic board, schematically indicated 15, carries a
respective circuit assembly arranged for controlling the actuator
means and consequently for controlling the modulation function
performed by the modulator unit.
[0020] It should be noted that, immediately upstream of the valve
seat 12, the pressure is equal to the regulated pressure Pr,
whereas in a portion, indicated 16, immediately downstream of the
valve seat, the gas pressure is equal to the delivery pressure
Pu.
[0021] According to the invention, the control system has a duct 17
which puts the calibration chamber 8 into flow communication with
the portion 16 of the delivery duct 1 downstream of the modulation
valve. The connection is such that the delivery-pressure signal Pu
is brought into the calibration chamber 8 so that the pressure to
which the diaphragm 7 is subjected in the chamber is the sum of the
calibration pressure and of the delivery pressure Pu. As a result
of the balancing of the pressures on the sides of the diaphragm 7,
the pressure Pr regulated by the regulator is consequently equal to
the sum of the contributions of the pressures Pt and Pu
(Pr=Pt+Pu).
[0022] If the ratio between the pressures downstream and upstream
of the modulator, which ratio defines the pressure gain of the
system in open circuit (that is, the result that can be achieved at
the output of the system without the connection of the duct 17), is
indicated G (G=Pu/Pr), then according to the control system of the
invention, the quantity Pu varies in accordance with the following
law: Pu=Pt(1/G-1).
[0023] As a result, as Pu decreases, the gain G decreases,
permitting an increase in the resolution R, where R=1(dPu/dX), in
which R is linked with the movement of the closure member 13 of the
modulator unit along its own principal axis X, and is inversely
proportional to Pu. In particular, if the closure member 13 of the
modulator unit 11 is operated by a linear actuator of any type
having levels (with a preselected number of "steps"), then
R=1/(dPu/dStep).
[0024] FIG. 3 shows a graph with "Pu" on the ordinate and the
levels (steps) on the abscissa, in which curve A (solid line)
represents the system in open circuit, without the connection of
the duct 17, and curve B (broken line) represents the system
according to the invention.
[0025] With particular reference to FIG. 2, a second embodiment of
the system according to the invention, in which details similar to
those of the previous embodiment are indicated by the same
reference numerals, provides for the modulator unit 11 to be
associated with an air-gas mixer device 18 in order to obtain a
combustible mixture to be transferred to the burner. More
particularly, the air-flow sent into the mixer 18 is generated by a
fan 19 the output of which is directed into a mixing region, for
example, formed with a Venturi duct into which the gas delivered by
the modulator unit 11 at the pressure Pu is injected.
[0026] The system has a duct 20 for putting the calibration chamber
8 of the pressure regulator into flow communication with a casing
portion 21 of the fan 19 defined in the region of the outlet of the
fan 19, upstream of the air-gas mixing region, in which the output
pressure of the fan, indicated Pv, is present.
[0027] As a result, the pressure Pr regulated by the regulator 4 is
equal, in this case, to the sum of the contributions of the
calibration pressure and of the fan output pressure (Pr=Pt+Pv).
Since the pressure Pv is correlated proportionally with the
gas-delivery pressure Pu, in this embodiment also, the resolution
of the degree of "discretization" is consequently variable in
dependence on the gas-delivery pressure Pu (or, correspondingly, on
the air-output pressure Pv).
[0028] An electronic board for controlling the motor-driven
actuator of the modulator unit 11 is indicated 22 and a
differential pressure sensor is indicated 23; the pressure value
detected by the pressure sensor 23 is sent to the electronic board
22. The pressure sensor 23 is provided with detection terminals
which are arranged, respectively, in the air duct 20 and in the
gas-delivery duct, in a section of the gas-delivery duct upstream
of the air-gas mixing region (FIG. 2). The gas pressure is
modulated by operation of the actuator 11, by means of the signal
processed by the electronic board 22, in dependence on the pressure
signal detected by the sensor 23, in order to keep the pressure
differential at a suitable value such as to ensure that the ratio
between the air flow-rate and the gas flow-rate remains
constant.
[0029] For some applications, a flow sensor may be selected as the
sensor 23, in particular for applications in which the pressure
differential tends to adopt values close to zero.
[0030] The invention thus achieves the objects proposed, affording
the advantages mentioned above over known solutions.
* * * * *