U.S. patent application number 14/110241 was filed with the patent office on 2014-07-10 for evaporator burner for a mobile heating device.
This patent application is currently assigned to Webasto SE. The applicant listed for this patent is Webasto SE. Invention is credited to Steffen Weber.
Application Number | 20140193759 14/110241 |
Document ID | / |
Family ID | 46026593 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140193759 |
Kind Code |
A1 |
Weber; Steffen |
July 10, 2014 |
Evaporator burner for a mobile heating device
Abstract
An evaporator burner for a mobile heating device is provided,
with: a combustion chamber surrounding a combustion space for
converting fuel with combustion air; an evaporator receiving
portion for receiving an evaporator body for evaporating liquid
fuel, the evaporator receiving portion being arranged at a rear
side of the combustion space; a burner cap which closes the
combustion space at the rear side of the evaporator receiving
portion and which is connected to the combustion chamber; and a
fuel pipe for supplying fuel to the evaporator body, the fuel pipe
opening into the evaporator receiving portion. The fuel pipe is
thermally coupled to the burner cap and the burner cap is provided
with an air heat exchanger for cooling the burner cap over which
supplied combustion air is guidable during operation.
Inventors: |
Weber; Steffen;
(Brandenburg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Webasto SE |
Stockdorf/Gauting |
|
DE |
|
|
Assignee: |
Webasto SE
Stockdorf/Gauting
DE
|
Family ID: |
46026593 |
Appl. No.: |
14/110241 |
Filed: |
April 5, 2012 |
PCT Filed: |
April 5, 2012 |
PCT NO: |
PCT/DE2012/100093 |
371 Date: |
January 6, 2014 |
Current U.S.
Class: |
431/314 ;
431/328 |
Current CPC
Class: |
F23D 14/145 20130101;
F23D 3/40 20130101; F23D 3/22 20130101; F23D 2900/21002 20130101;
F23D 11/443 20130101; F23D 2900/00016 20130101; F23C 7/06
20130101 |
Class at
Publication: |
431/314 ;
431/328 |
International
Class: |
F23D 3/22 20060101
F23D003/22; F23D 14/14 20060101 F23D014/14; F23D 3/40 20060101
F23D003/40 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2011 |
DE |
10 2011 050 025.1 |
Claims
1. An evaporator burner for a mobile heating device, comprising: a
combustion chamber surrounding a combustion space for converting
fuel with combustion air; an evaporator receiving portion for
receiving an evaporator body for evaporating liquid fuel, the
evaporator receiving portion being arranged at a rear side of the
combustion space; a burner cap which closes the combustion space at
the rear side of the evaporator receiving portion and which is
connected to the combustion chamber; and a fuel pipe for supplying
fuel to the evaporator body, the fuel pipe opening into the
evaporator receiving portion; wherein the fuel pipe is thermally
coupled to the burner cap and the burner cap is provided with an
air heat exchanger for cooling the burner cap over which supplied
combustion air is guidable during operation.
2. The evaporator burner according to claim 1, wherein the burner
cap is connected to the combustion chamber only via one
substantially line-shaped junction.
3. The evaporator burner according to claim 1, wherein the air heat
exchanger comprises a plurality of heat exchanger fins.
4. The evaporator burner according to claim 1, wherein the air heat
exchanger is arranged in the combustion air supply upstream of the
combustion space.
5. The evaporator burner according to claim 1, wherein the burner
cap is made from aluminum or from an aluminum alloy.
6. The evaporator burner according to claim 1, wherein the burner
cap and the evaporator receiving portion are formed as separate
components.
7. The evaporator burner according to claim 6, wherein the burner
cap and the evaporator receiving portion are arranged spatially
spaced from each other.
8. The evaporator burner according to claim 1, wherein the
combustion chamber comprises a plurality of holes for supply of
combustion air into the combustion space.
Description
[0001] The present invention relates to an evaporator burner for a
mobile heating device.
[0002] Mobile heating devices are known which can e.g. be used as
vehicle heating devices for heating a vehicle. In vehicle
applications, such mobile heating devices are e.g. employed as
supplementary heaters capable of providing additional heat when the
propulsion engine of the vehicle is running or as parking heaters
capable of providing heat for heating purposes both when the
propulsion engine is running and when the propulsion engine is
turned off.
[0003] In the present context, the term "mobile heating device"
means a heating device which is designed and correspondingly
adapted for use in mobile applications. This means in particular
that it is transportable (e.g. fixedly mounted in a vehicle or only
placed there for transport) and not exclusively adapted for
permanent stationary use, as would be the case for heating of a
building. The mobile heating device can be fixedly installed in a
vehicle (land vehicle, boat, etc.), in particular in a land
vehicle. In particular, it can be adapted for heating a vehicle
interior, such as of a land vehicle, a water vehicle or an air
plane, and a partly open room as can be found in boats, in
particular yachts. The mobile heating device can also temporarily
be used stationary, such as e.g. in big tents, containers (e.g.
containers for building sites), and the like. According to a
preferred further development, the mobile heating device is adapted
as a parking heater or a supplementary heater for a land vehicle,
such as e.g. a mobile home, a recreational vehicle, a bus, a
passenger car, etc.
[0004] In mobile heating devices comprising an evaporator burner,
often liquid fuel which can e.g. be the fuel also used for a
combustion engine of the vehicle, such as benzine, diesel or
ethanol, is fed via a fuel pipe to an evaporator body consisting of
a porous, absorbent material. The fuel is evaporated on the
evaporator body. The fuel is intermixed with combustion air which
is also supplied and converted in an exothermal reaction thereby
generating heat. Usually, the evaporator burners are not operated
continuously but instead--depending on the required heating
power--are relatively often switched on and off again. During
turning off, usually first the fuel supply is terminated by
switching off a fuel conveying pump and combustion air is at first
still supplied in order to enable as much as possible residue-free
and clean burning out. As a consequence of this, during the time of
burning out when a high temperature still exists in the combustion
chamber of the burner, a stationary amount of fuel is present in
the fuel pipe. If a relatively good thermal connection exists
between the combustion space and the fuel pipe, a high thermal load
can act on a stationary amount of fuel in the fuel pipe in
particular in the time period immediately after stopping the fuel
supply. As a consequence of this, e.g. polymerization of fuel
components can take place in the fuel pipe which can result in
deposits in the fuel pipe which are not soluble in the unaltered
fuel. These deposits can lead to an increase in flow resistance in
the fuel pipe and ultimately to plugging of the fuel supply.
[0005] It is the object of the present invention to provide an
improved evaporator burner for a mobile heating device with which
in particular the risk of plugging in the fuel pipe is reduced.
[0006] The object is solved by an evaporator burner for a mobile
heating device according to claim 1. Further developments are
specified in the dependent claims.
[0007] The evaporator burner comprises: a combustion chamber
surrounding a combustion space for converting fuel with combustion
air; an evaporator receiving portion for receiving an evaporator
body for evaporating liquid fuel, the evaporator receiving portion
being arranged at a rear side of the combustion space; a burner cap
which closes the combustion space at the rear side of the
evaporator receiving portion and which is connected to the
combustion chamber; and a fuel pipe for supplying fuel to the
evaporator body, the fuel pipe opening into the evaporator
receiving portion. The fuel pipe is thermally coupled to the burner
cap and the burner cap is provided with an air heat exchanger for
cooling the burner cap over which supplied combustion air is
guidable during operation.
[0008] By the thermal coupling of the fuel pipe to the burner cap,
efficient heat removal from the fuel pipe to the burner cap can
take place, thus the fuel pipe can be cooled. At the same time, the
burner cap can efficiently be maintained on a relatively low
temperature level by heat transfer to supplied combustion air via
the air heat exchanger. Since the burner cap is used as a heat sink
for the fuel pipe, an additional heat sink for the fuel pipe formed
as a separate component can be dispensed with. This allows a
cost-efficient and compact realization. Since an undesirably high
temperature rise in the region of the fuel pipe can be prevented,
the risk of plugging in the fuel pipe is reduced. The air heat
exchanger can e.g. be formed as a separate element or can also be
formed in one piece with the burner cap from the material of the
burner cap.
[0009] According to one development, the burner cap is connected to
the combustion chamber only via one substantially line-shaped
junction. In this case, the heat conduction from the combustion
chamber to the burner cap is suppressed since the line-shaped
junction allows for at most weak heat conduction towards the burner
cap. Thus, the burner cap can reliably be held on a relatively low
temperature level and forms a reliable heat sink for the fuel pipe.
It is however also possible to realize the burner cap thermally
insulated from the burner chamber and other hot components in
another manner.
[0010] According to one development, the air heat exchanger
comprises a plurality of heat exchanger fins. In this case, good
heat transfer to the supplied combustion air is achieved by a large
surface such that heat can efficiently be removed from the burner
cap. The heat exchanger fins can comprise different shapes.
[0011] According to one development, the air heat exchanger is
arranged in the combustion air supply upstream of the combustion
space. The air heat exchanger can in particular be arranged
directly upstream of the combustion space to achieve a particularly
compact construction. By the arrangement upstream of the combustion
space, the combustion air can be pre-heated through this heat
transfer before entry into the combustion space.
[0012] According to one development, the burner cap is made from
aluminum or from an aluminum alloy. In comparison to a realization
in which the burner cap is e.g. formed from stainless steel, due to
the high heat conductivity of aluminum or aluminum alloys efficient
heat distribution and heat removal is provided for in the burner
cap in this realization such that the heat to be removed is
efficiently removed to the air heat exchanger.
[0013] According to one development, the burner cap and the
evaporator receiving portion are formed as separate components. In
this case, also undesired high heat transfer from the evaporator
receiving portion into the burner cap can be prevented such that
the burner cap can be maintained on a low temperature as a heat
sink. If the burner cap and the evaporator receiving portion are
arranged spatially spaced from each other, undesired heat input
from the evaporator receiving portion into the burner cap can be
prevented in a particularly reliable manner.
[0014] According to one development, the combustion chamber
comprises a plurality of holes for supply of combustion air into
the combustion space.
[0015] Further advantages and developments will become apparent
from the following description of an embodiment with reference to
the FIGURE.
[0016] FIG. 1 is a schematic illustration of an evaporator burner
for a mobile heating device in the region of an evaporator
receiving portion and of a burner cap.
[0017] In the following, an embodiment is described with reference
to FIG. 1. In FIG. 1, a region of an evaporator receiving portion 2
and of a burner cap 8 of an evaporator burner 1 for a mobile
heating device is schematically depicted. In the illustration of
FIG. 1, a schematic sectional illustration in a plane containing a
main axis Z of the evaporator burner 1 is shown. The evaporator
burner 1 can e.g. comprise substantially rotational symmetry with
respect to the main axis Z. The evaporator burner 1 can e.g. be
formed for a vehicle heating device, in particular a supplemental
heater or a parking heater. The evaporator burner 1 is in
particular formed to convert a mixture of evaporated fuel and
combustion air in a combustion space 4 thereby generating heat. The
generated heat is transferred to a medium to be heated in a heat
exchanger (not shown). The medium to be heated can e.g. be formed
by air or by a cooling liquid. In the schematic illustration of
FIG. 1, in particular the heat exchanger, the discharge line for
the hot combustion exhaust gases, the combustion air conveying
device (e.g. a blower) which is also provided, the fuel conveying
device (e.g. a metering pump), the control unit for controlling the
evaporator burner 1, etc. are not depicted. These components are
well known and described in detail in the prior art.
[0018] The evaporator burner 1 comprises an evaporator receiving
portion 2 in which a porous, absorbent evaporator body 5 is
arranged. In the embodiment, the evaporator receiving portion 2
comprises a substantially cup-shaped shape with a hole in the
bottom. The evaporator body 5 is accommodated in the cup-shaped
depression of the evaporator receiving portion 2 and can in
particular be fixedly held therein, e.g. by welding, soldering,
clamping or making use of a suitable securing element. The
evaporator body 5 can e.g. in particular be formed by a non-woven
fabric of metal fibers or by a plurality of layers of non-woven
fabric of metal fibers.
[0019] A fuel pipe 6 for supplying fuel to the evaporator body 5 is
provided. The fuel pipe 6 opens into the evaporator receiving
portion 2 and is connected to a fuel conveying device (not shown)
by which fuel can be conveyed through the fuel pipe 6 in a
predetermined amount, as schematically depicted by an arrow B. The
fuel pipe 6 is fixedly connected to the evaporator receiving
portion 2, e.g. by welding or soldering.
[0020] The combustion space 4 is circumferentially bordered by a
combustion chamber 7 which can e.g. be formed by a substantially
cylindrical component made of temperature resistant steel. The
combustion chamber 7 is provided with a plurality of holes 7a via
which the combustion air can be supplied to the combustion space 4,
as schematically illustrated by branching arrows in FIG. 1.
[0021] Further, a burner cap 8 is provided which closes the
combustion space 4 at the rear side of the evaporator receiving
portion 2. The burner cap 8 is made from aluminum or from an
aluminum alloy and can e.g. be produced in a die casting process.
The burner cap 8 also comprises a substantially cup-like shape and
is arranged such that a surrounding side wall reaches around the
evaporator receiving portion 2. The burner cap 8 and the evaporator
receiving portion 2 are formed as separate components which are
arranged spatially spaced from each other. In a bottom region of
the burner cap 8, a through-hole is provided through which the fuel
pipe 6 passes. The combustion chamber 7 is fixedly connected to the
burner cap 8 such that the combustion space 4 is closed at the rear
side. In the embodiment, the combustion chamber 7 is connected to
the burner cap 8 only via a substantially line-shaped junction. In
the embodiment, the circumferential side wall of the burner cap 8
comprises a circumferential narrow protruding rib 8a to which the
combustion chamber 7 is fixed in a substantially line-shaped way.
The combustion chamber 7 can be fixed to the protruding rib 8a by
e.g. welding, soldering or caulking. Due to the connection of the
combustion chamber 7 to the burner cap 8 only via the protruding
rib 8a, heat transfer from the combustion chamber 7 to the burner
cap 8 via heat conduction is suppressed or strongly reduced,
respectively, so that the protruding rib 8a serves as thermal
insulation for the burner cap 8.
[0022] The fuel pipe 6 is thermally coupled to the burner cap 8
such that heat transfer from the fuel pipe 6 to the burner cap 8
can take place. In the depicted embodiment, the fuel pipe 6
comprises a circumferential projection 6a via which the fuel pipe 6
is heat-conductively connected to the burner cap 8. The connection
can e.g. be realized by soldering or welding. Instead of a
circumferential projection 6a, the heat pipe 6 can also be
heat-conductively connected to the burner cap 8 in another manner.
For example, a heat-conductive element, such as a heat-conductive
pad, can also be provided between the fuel pipe 6 and the burner
cap 8 for heat exchange.
[0023] The burner cap 8 is provided with an air heat exchanger 8b
for cooling or heat removal, respectively, from the burner cap 8.
The air heat exchanger 8b comprises a plurality of heat exchanger
fins (preferably a multitude of heat exchanger fins) which are
distributed over the outer circumference of the burner cap 8. The
heat exchanger fins project into the flow of combustion air in a
combustion air supply upstream of the combustion space 4. In
operation, the supplied combustion air flows around the heat
exchanger fins, as schematically depicted by arrows L in FIG. 1,
such that combustion air is fed over the air heat exchanger 8b and
that the burner cap 8 is cooled in this way. The air heat exchanger
8b can e.g. be formed in one piece with the burner cap 8 from the
material of the burner cap 8 or can also be heat-conductively
coupled to the burner cap 8 as a separate component. E.g. the air
heat exchanger 8b can be formed by heat exchanger fins molded on
the outer wall of the burner cap 8.
[0024] Due to the described realization, in the embodiment the fuel
pipe 6 is thermally coupled to the burner cap 8 such that the
burner cap 8 serves as a heat sink for the fuel pipe 6. Due to the
construction out of aluminum or an aluminum alloy, the burner cap 8
comprises high heat conductivity and the heat is efficiently
conducted to the air heat exchanger 8b at which it is transferred
to the supplied combustion air. Further, in this way the
temperature of the burner cap 8 is maintained as low as possible
during operation such that thermal insulation of the burner cap 8
from hot components is provided. This is e.g. achieved in that the
combustion chamber 7 is connected to the burner cap 8 only through
a substantially line-shaped junction and not through a plane-shaped
contact area.
[0025] Since the burner cap 8 efficiently serves as a heat sink for
the fuel pipe 6 in the described manner, conglutination or plugging
of fuel in the fuel pipe 6 due to an undesired large heat input can
reliably be prevented without requiring a separate heat sink as a
separate additional component.
[0026] Although this is not illustrated in FIG. 1 and was not
explicitly described, the combustion space 4 is surrounded in known
manner by a heat exchanger for transferring the heat which is set
free to a medium to be heated, such as air or a fluid. Further, a
casing is provided in a manner per se known in which the evaporator
burner is accommodated and which provides appropriate air
conductance for the combustion air supply.
* * * * *