U.S. patent application number 11/719573 was filed with the patent office on 2009-09-24 for burner for a heater device with improved fuel supply.
Invention is credited to Michael Pohner, Jan Steffens, Steffen Weber, Friedrich Widemann.
Application Number | 20090239184 11/719573 |
Document ID | / |
Family ID | 35985443 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090239184 |
Kind Code |
A1 |
Pohner; Michael ; et
al. |
September 24, 2009 |
BURNER FOR A HEATER DEVICE WITH IMPROVED FUEL SUPPLY
Abstract
A burner for a heater, especially for use in motor vehicles,
with a burner nozzle (12) for supplying and atomizing of fuel,
which has a fuel needle (14) for supplying fuel to the burner (10)
and a combustion air supply (16) for supplying combustion air to
the burner, and a starting zone (18) in which ignition of the fuel
to start the burner takes place. It is provided that, by choosing
the inside diameter of the fuel needle (14) the exit speed of the
fuel is predetermined such that, during the starting phase of the
burner (10), fuel in essentially unatomized form reaches the
starting zone (18).
Inventors: |
Pohner; Michael; (Munchen,
DE) ; Widemann; Friedrich; (Munchen, DE) ;
Weber; Steffen; (Anklam, DE) ; Steffens; Jan;
(Isenwang, DE) |
Correspondence
Address: |
ROBERTS MLOTKOWSKI SAFRAN & COLE, P.C.;Intellectual Property Department
P.O. Box 10064
MCLEAN
VA
22102-8064
US
|
Family ID: |
35985443 |
Appl. No.: |
11/719573 |
Filed: |
November 16, 2005 |
PCT Filed: |
November 16, 2005 |
PCT NO: |
PCT/DE05/02060 |
371 Date: |
May 1, 2009 |
Current U.S.
Class: |
431/171 |
Current CPC
Class: |
F23D 2900/11401
20130101; F23D 9/00 20130101; F23D 11/24 20130101; F23D 11/406
20130101; F23D 11/408 20130101 |
Class at
Publication: |
431/171 |
International
Class: |
F23M 9/06 20060101
F23M009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 17, 2004 |
DE |
10 2004 055 437.4 |
Claims
1-14. (canceled)
15. Burner for a heater for use in motor vehicles, comprising: a
combustion chamber a burner nozzle for supplying and atomizing of
fuel having a fuel needle for supplying fuel to the combustion
chamber and a combustion air supply for supplying combustion air to
the combustion chamber, and a starting zone in which ignition of
the fuel to start the burner takes place, wherein the inside
diameter of the fuel needle produces a predetermined exit speed of
the fuel such that, during a starting phase of the burner, fuel in
essentially unatomized form reaches the starting zone.
16. Burner as claimed in claim 15, wherein the inside diameter of
the fuel needle is between 0.5 mm and 0.7 mm.
17. Burner as claimed in claim 15, wherein the inside diameter of
the fuel needle is about 0.6 mm.
18. Burner as claimed in claim 15, wherein the starting zone is a
starting chamber into which an ignition element projects.
19. Burner as claimed in claim 15, further comprising a heat shield
having a generally centrally located passage therethrough that is
surrounded by a ring openings in the heat shield; wherein: the heat
shield is located between the burner nozzle and the combustion
chamber, the combustion air supply comprises a primary air supply
directed from the burner nozzle through the passage in the heat
shield and a secondary air supply directed to the combustion
chamber through said openings in the heat shield, and said openings
are provided with air guide elements.
20. Burner as claimed in claim 19, wherein the air guide elements
are formed by tabs which are integral with the heat shield and
which project toward the combustion chamber.
21. Burner as claimed in claim 20, wherein the tabs are made at
different angles relative to at least one of the radius and surface
of the heat shield.
22. Burner as claimed in claim 21, wherein the tabs are formed of
groups of tabs, the tabs of each group being of essentially the
same angle relative to said at least one of the radius and surface
of the heat shield.
23. Burner as claimed in claim 19, wherein: the combustion chamber
has a burnout zone and secondary air is supplied to the burnout
zone with a higher angular momentum than secondary air which is
supplied to the starting zone.
24. Burner as claimed in claim 19, wherein the heat shield has an
opening for routing and ignition element through.
25. Burner as claimed in claim 15, wherein: the combustion chamber
is essentially axially symmetrical, there is a baffle plate in the
combustion chamber, and wherein the baffle plate has a defined
curvature in a downstream axial direction into the combustion
chamber.
26. Burner as claimed in claim 23, further comprising a baffle
plate in the combustion chamber, the baffle plate having a defined
curvature there in a direction toward the burnout zone.
27. Burner as claimed in claim 26, wherein an outer periphery of
the baffle plate defines a plane and wherein a ratio between a
maximum axial distance of a portion of the baffle plate from this
plane and the diameter of the baffle plate is between 0.07 and
0.21.
28. Burner as claimed in claim 27, wherein the ratio between the
maximum axial distance of the baffle plate from said plane and the
diameter of the baffle plate is about 0.14.
29. Burner as claimed in claim 25, wherein an outer periphery of
the baffle plate defines a plane and wherein a ratio between a
maximum axial distance of a portion of the baffle plate from this
plane and the diameter of the baffle plate is between 0.07 and
0.21.
30. Burner as claimed in claim 29, wherein the ratio between the
maximum axial distance of the baffle plate from said plane and the
diameter of the baffle plate is about 0.14.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The invention relates to a burner for a heater, especially
for use in motor vehicles, with a burner nozzle for supply and
atomization of fuel, which has a fuel needle for supplying fuel to
the burner and a combustion air supply for supplying combustion air
to the burner, and a starting zone in which ignition of the fuel to
start the burner takes place.
[0003] 2. Description of Related Art
[0004] Burners of the initially mentioned type, which are also
called atomization burners or spray burners, are used especially in
auxiliary heaters and engine independent heaters for motor
vehicles.
[0005] There are numerous requirements for these burners,
especially with respect to reliable and largely emission-free
starting behavior and stable combustion operation. Furthermore, an
effort is made to build heaters which can be used in different
installation positions.
[0006] With respect to starting behavior, various operating
parameters must be matched to one another. On the one hand, it is
necessary during burner starting to make available a relatively
rich fuel-air mixture in the starting zone, and on the other hand,
however, providing a sufficient amount of primary combustion air is
necessary to ensure transport of fuel from the fuel needle to the
starting zone.
[0007] The requirement of allowing different installation positions
of the heater is associated with problems relating to starting
behavior. In order to be specifically able to transport fuel into
the starting zone with little primary air supply, in the past,
orienting the fuel needle with the outlet opening pointed down had
to be tolerated; this resulted in the entire burner having to be
mounted in the vertical installation position.
[0008] To ensure stable combustion operation of the burner,
likewise, mutually contradictory requirements must be satisfied. On
the one hand, good intermixing of the fuel and air is always
required, and on the other hand, in the core region of the flame,
especially during the starting phase, it is undesirable to cause
overly high air proportions and overly high swirling.
SUMMARY OF THE INVENTION
[0009] The object of the invention is to overcome the described
problems of the prior art at least in part and especially to enable
reliable and low-emission starting behavior with little dense smoke
in different installation positions.
[0010] This object is achieved by the exit speed of the fuel being
predetermined by choosing the inside diameter of the fuel needle
such that, during the starting phase of the burner, fuel in
essentially unatomized form reaches the starting zone.
[0011] The invention is based on a generic burner in that, by
choosing the inside diameter of the fuel needle, the exit speed of
the fuel is predetermined such that, during the starting phase of
the burner, fuel in essentially unatomized form reaches the
starting zone. By reducing the inside diameter of the fuel needle
as compared to fuel needles in the heaters of the prior art, at the
same fuel delivery volume, the exit speed of the fuel is increased.
In this way, for any installation position, it is possible for the
fuel jet to reach the starting zone from the exit opening of the
fuel needle. In particular, for a small primary air amount, for
which the supplied primary air should have only little angular
momentum, an essentially unatomized fuel jet can reach the starting
zone. Consequently, the burner starts reliably and formation of
dense smoke during starting is distinctly reduced.
[0012] It is preferred that the inside diameter of the fuel needle
be between 0.5 mm and 0.7 mm. Compared to exit speeds for fuel
needles of the prior art in which the inside diameter is in the
region of 0.8 mm, the exit speed for inside diameters between 0.5
mm and 0.7 mm can be almost doubled or even more than doubled.
[0013] It is especially preferred that the inside diameter of the
fuel needle is roughly 0.6 mm. At this inside diameter, in full
load operation, i.e., at a fuel mass flow of 0.5 kg/h, exit speeds
of more than 0.6 m/s are possible, while for an inside diameter of
0.8 mm, the exit speed is in the region of 0.35 m/s. The exit speed
in partial load operation rises accordingly, i.e., for a fuel mass
flow of 0.2 kg/h, from roughly 0.14 m/s to roughly 0.25 nm/s. For a
corresponding choice of construction properties or of operating
parameters, the goal of an essentially unatomized jet which reaches
the starting zone when the heater is being started can be achieved
even with an otherwise conventional fuel needle with an inside
diameter of roughly 0.8 mm.
[0014] It is useful for the starting zone to be made as a starting
chamber into which an ignition element projects. The wall of the
combustion chamber can surround the ignition element in this way.
During starting operation, the "ballistic" fuel jet can then wet
the ignition element and the combustion chamber wall with fuel so
that the combustion chamber wall and adjacent components, after
being heated, are used as wall vaporizers.
[0015] According to one especially preferred embodiment of this
invention, it is provided that, in addition to the primary air
which is supplied from the burner nozzle through a heat shield
located between the burner nozzle and the combustion chamber,
secondary air can be supplied to the combustion chamber through
openings provided in the heat shield, and that the openings are
provided with air guide elements. A heat shield is fundamentally
useful to shield the nozzle and the fuel supply against the heat
energy present in the combustion chamber. Furthermore, secondary
air is supplied to the combustion space via the heat shield. By the
openings for secondary air supply being provided with air guide
elements, this secondary air can be supplied in a controlled manner
so that combustion operation, both with respect to starting
operation and also for continuous operation, can be influenced in a
specific manner.
[0016] It is useful for the air guide elements to be formed by tabs
which are made integrally with the heat shield and which project in
the direction of the combustion chamber. This heat shield can be
easily produced, for example, by the tabs being formed with a
v-shaped punching tool and being bent out of the plane of the heat
shield after or with the punching process.
[0017] The invention is also usefully developed in that the tabs
are made at different angles to the surface of the heat shield
and/or to the radius of the heat shield. If the tabs extend almost
perpendicularly to the radius of the heat shield, this delivers
strong angular momentum, while tabs with a smaller angle relative
to the radius deliver smaller angular momentum. Tabs which assume a
small angle to the surface of the heat shield produce air flows
which have a large radial component and a small axial component,
while for tabs with large angles relative to the surface of the
heat shield, the axial component dominates. In this way, it is
possible to route secondary air with low angular momentum into the
core region of flame formation. Thus, on the one hand, the air
required for combustion is supplied; but there is no excess angular
momentum which would adversely affect stabilization of the flame.
In particular, the secondary air can be divided depending on the
alignment of the individual air guide elements.
[0018] According to another embodiment, it is provided that the
tabs are grouped at essentially identical angles relative to the
surface of the heat shield and/or to the radius of the heat shield.
Defined flow states in the combustion chamber are formed by the
collective alignment of the tabs.
[0019] The invention is also usefully executed such that the burner
has a burnout zone and that the secondary air which is supplied to
the burnout zone has higher angular momentum than the secondary air
which is supplied to the starting zone. High angular momentum is
desired in the burnout zone. In particular, a radially inside
swirled backflow region improves the burnout and provides for the
combustion chamber volume being effectively used.
[0020] Furthermore, it is provided that the heat shield has an
opening for routing the ignition element through.
[0021] In one especially preferred embodiment of the invention, it
is also provided that the combustion chamber is essentially axially
symmetrical, that there is a baffle plate in the combustion
chamber, and that the baffle plate has a given curvature in the
axial direction. Due to the curvature of the baffle plate, there is
a defined shaping of the baffle plate which is independent of
temperature. For the baffle plates of the prior art which are made
flat, this is, among others, not the case since, depending on the
temperature, spontaneous changes of shape can occur which can
adversely affect the combustion behavior of the burner.
[0022] It is preferred that there is a curvature in the direction
of the burnout zone. In this way, a sufficient space in the region
of the starting chamber is made available. Furthermore, it has been
found that the curvature in the direction of the burnout zone does
not have an adverse effect on the flow behavior in this zone. In
particular, the pronounced swirled backflow region is maintained in
the radially inner region of the burnout zone.
[0023] According to one preferred embodiment of the invention, it
is provided that the outer periphery of the baffle plate defines a
plane and that the ratio between the maximum axial distance of the
baffle plate from this plane and the diameter of the baffle plate
is between 0.07 and 0.21.
[0024] The most heavily arched point of the baffle plate is
preferably essentially in the center of the arrangement with
respect to the radial coordinate. From the plane which is defined
by the outer periphery of the baffle plate, this point has an axial
distance which is defined by the indicated ratio to the
diameter.
[0025] In this connection, it is especially preferred that the
ratio between the maximum axial distance of the baffle plate from
the plane and the diameter of the baffle plate is roughly 0.14. For
example the round diameter of baffle plate is roughly 40 mm, while
the curvature has a value of roughly 5.7 mm.
[0026] The invention is based on the finding that the novel fuel
supply with a fuel needle with a reduced exit cross section,
especially in combination with the novel heat shield and the novel
baffle plate, can greatly improve the operating behavior of a
burner. This relates especially to the starting behavior, the
stability of burner operation and possibilities with respect to the
installation position of the burner in the motor vehicle.
[0027] The invention is explained by way of example with reference
to the accompanying drawings using preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a sectional view of the burner in accordance with
the invention;
[0029] FIG. 2 is a perspective of a burner flange with the heat
shield inserted into it; and
[0030] FIG. 3 is a perspective of the heat shield.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In the following description of preferred embodiments of the
invention, the same reference numbers label the same or comparable
components.
[0032] FIG. 1 shows a sectional view of the burner in accordance
with the invention. The burner 10 in accordance with the invention
has a nozzle 12 which is securely joined to the heat shield 24. The
heat shield 24 together with a burner tube 40 which is connected to
the heat shield 24 defines a combustion chamber 22. The combustion
chamber tube 40 is surrounded by an outer pipe 42 which forms the
burner flange. A flame tube 38 is attached to this outer pipe 42.
The connections between the heat shield 24 and the combustion
chamber tube 40 or between the combustion chamber tube 40, the
outer pipe 42 and the flame tube 38 are generally welded
connections. On the fuel nozzle 12, there is a fuel supply 50 which
has a metal pipe 52 for supplying of fuel and a fuel needle 14 for
injection of fuel into the combustion chamber 22. Furthermore, in
the region of the fuel nozzle 16, there are channels for supplying
of primary combustion air into the fuel nozzle 20 which flows past
the fuel needle 14 in order to then flow along the radially
widening air guide of the fuel nozzle 12 in the direction of the
combustion chamber, and finally, into the combustion chamber 22.
The radial widening of the air guide achieves improved atomization
due to the Venturi effect. Within the combustion chamber 22, there
is also a baffle plate 36 which has an advantageous curvature. This
curvature in the direction of the burnout zone 32 is advantageous
since, in this way, heat-induced spontaneous changes in the shape
of the baffle plate 36 are prevented. By curving the baffle plate
36 in the direction of the burnout zone 32, moreover, a sufficient
space is available for accommodating the starting chamber 18. The
wall which defines the starting chamber 18 is welded to the baffle
plate 36.
[0033] FIG. 2 shows a perspective view of a burner flange with the
heat shield inserted into it, and FIG. 3 shows a perspective view
of heat shield 24. Furthermore, reference is likewise made below to
burner components as shown in FIG. 1. The heat shield 24 has a
central opening 48 through which the fuel-air mixture which has
been delivered from the nozzle 12 enters the combustion chamber.
Furthermore, there is a laterally arranged opening 34 through which
the ignition element 20 is routed. On the heat shield 24, there are
attachment pins 44, 46 to which the nozzle 12 is attached. The heat
shield 24 also has a host of openings 26 through which secondary
air can enter the combustion chamber 22. On the side of the heat
shield 24 facing the combustion chamber 22, there are triangular
air guide elements 28, 30. The air guide elements 28, 30 cause
division of the secondary air based on the different angles
relative to the radius of the heat shield 24.
[0034] A first group of air guide elements 28 are aligned at a
large angle with respect to the radius of the heat shield 24, i.e.,
their alignment is essentially or almost tangential. Based on this
alignment, the secondary air passing through the corresponding
openings 26, with an exit flow direction indicated by the arrow,
will overflow into the burnout zone 32 past the baffle plate 36
with a high angular momentum. This air which is provided with high
angular momentum flows in the radially outlying region of the
burnout zone 32 into the posterior region of the combustion chamber
22, i.e., into the region of the combustion chamber 22 which faces
away from the heat shield 24, and then, with high swirling back in
the central region in the direction of the baffle plate 36.
Consequently advantageous mixing of the gaseous components in the
burnout zone 32 occurs.
[0035] Another group of air guide elements 30 are aligned at a
smaller angle relative to the radius of the heat shield 24 and also
have a smaller angle relative to the surface of the heat shield 24
than the air guide elements 28. Consequently, these air guide
elements 30 route the secondary air with an exit flow direction,
indicated by another arrow, into the core region of the flame with
low angular momentum; this especially benefits stable combustion
chamber behavior.
[0036] Thus a novel spray burner is achieved which is improved with
respect to the possible installation positions, the starting
behavior and the behavior in continuous operation. Furthermore,
problems with respect to the temperature-induced changes of the
shape of the baffle plate are avoided.
[0037] The features of the invention disclosed in the above
specification, the drawings and the claims can be important to the
implementation of the invention both individually and also in any
combination.
* * * * *