Central heating for motor vehicles and such mobile units

With a fluid fuel driven standard heating for motor vehicles, whose combustion chambers are equipped as vaporizer burners, a heater plug with open heater coils up to now would be installed in the usual way. What is disadvantageous for the operation, particularly in the starting, is the voltage dependence of such a heater plug. Also, with time an increasing carbonization would be established. According to the invention the vaporizing of the liquid fuel occurs under a seal by the use of a rod heater plug. The ignition can--independent of voltage--occur with the help of a spark plug (high voltage electrode). In a construction design the vaporizer is developed as a heat pipe, in which the rod heater plug is arranged.

FIELD OF THE INVENTION 
The invention generally concerns central heating for motor vehicles and 
more particularly concerns a vaporizer burner for liquid fuel. 
BACKGROUND OF THE INVENTION 
There are different types of outside or standard heating for motor 
vehicles, airplanes and other mobile units. In regard to the special 
development of the burners one distinguishes for example between rotating 
distribution burners, spray gun burners, and vaporizer burners. The 
present invention relates to the last named type. 
In this type a vaporizer burner is arranged inside a somewhat concentric 
shell combustion chamber for blowing combustion air axially or 
tangentially into the combustion chamber. In the combustion chamber the 
vaporizer is situated such that it is mostly radial in relation to the 
combustion chamber. In the usual convention this heating consists of a 
heater plug with an exposed lying heater coil within a cylindrical body, 
in which for example with a fiber packing provided at a circumferential 
area, fuel will be lead. Through the insertion of the heater plug the fuel 
vaporizes, as it reaches the heating temperature for ignition. 
It has been observed that the starting of the operation of such a standard 
heater with a vaporizer burner experiences difficulties under certain 
circumstances. The reason being that the obtained temperature from the 
heater plug depends very heavily on the respective operating voltage at 
the given time. As is well known, the operating voltage in a motor vehicle 
is subject to considerable deviation (independent of loading conditions 
and independent of other loads of the board battery), so that the start of 
the burning activity is dependent on the working voltage that is directly 
at disposal. 
Further it is established, that after a certain amount of time of operation 
a carbonization of the heater plug takes place, whereby the operation at 
the starting process is even more unstable. The carbonization is fed back 
on it, so that the air and fuel reaches the heater plug. 
SUMMARY AND OBJECTS OF THE INVENTION 
It is an object of the invention to create a central heating arrangement 
for motor vehicles and the like, by which a reliable start of the burner 
operation is guaranteed. 
According to the invention, a rod heater plug is provided in the fuel 
evaporator or vaporizer, and for the starting of the burner, a high 
voltage electrode is arranged in the vicinity of the vaporizer. 
Preferably the rod heater plug is so arranged that the vaporizing process 
is sealed from the air. 
According to the invention, it is possible to do this without having heater 
plugs with open heater coils which had normally been utilized. The 
ignition occurs with the help of a spark plug (high voltage electrode). 
Thereby the starting process of the burner of the heating will be voltage 
independent. The temperature on the vaporizer thereby lies stable over a 
value around 300 degrees Celcius. 
In a further development of the invention, it is provided that the 
vaporizer is arranged approximately on the longitudinal center axis of the 
combustion chamber having a tangential air supply. Basically the 
combustion air blower can be axially arranged so that the combustion air 
will be blown into the combustion chamber in substantial axial symmetry. 
In this case, the vaporizer is arranged radially in relation to the 
combustion chamber. In the preferred development of the invention the 
delivery of the combustion air nevertheless occurs tangentially, while the 
vaporizer is axially arranged. This allows a compact construction of the 
entire central heating. 
In a variant of the invention, the vaporizer is provided with a perforated 
cylinder body, (for example, formed of metal or ceramics) with a filter 
liner or an inserted fiber packing, while the heater plug is arranged 
concentrically in the cylinder body. In another variant, the vaporizer is 
formed with a heat pipe, which the rod heater plug surrounds. Heat pipes 
are generally known. However, the heat pipe cooperating with the other 
features of the invention provides a heat transference, without outer 
influence, from the side of lower temperature to the side of higher 
temperature. This capacity is utilized by the invention. The fuel delivery 
occurs on the side of lower temperature, while on the other side of the 
heat pipe the vapor outlet leads to the combustion chamber. The rod heater 
plug is practically shut off from the air supply. The vaporized fuel 
arrives in the combustion chamber with a sufficiently high temperature. 
Also in this variant a tangential air supply is preferable provided for. 
Out of the above described advantages, from which the avoidance of an open 
heating coil is prominent, the possibility will in favorable ways be 
opened by the invention for flame control to be achieved with the help of 
a high voltage electrode. In addition to this, a voltage produced will be 
measured on the high voltage electrode through the ionization in the area 
of the electrode that varies with the intensity of the flame. 
A further object of the invention is to provide a heating arrangement which 
is dependable, safe, simple in design, rugged in construction and 
economical to manufacture. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its uses, reference 
is made to the accompanying drawings and descriptive matter in which 
preferred embodiments of the invention are illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, in particular, the invention embodied therein 
comprises a central heating unit for a vehicle or the like, including a 
vaporizer burner, generally designated 2 (22 in FIG. 2) which vaporizer 
burner is adapted for use with liquid fuel. The burner arrangement is 
included with a rod heating plug 6 positioned within the vaporizer burner 
unit. A high voltage electrode means 8 is provided positioned adjacent the 
vaporizer burner 2 for starting the vaporizer burner. 
FIG. 1 shows in a simplified representation a section of a vaporizer burner 
of a heating unit for a motor vehicle. The arrangement includes a middle 
section of a casing 1, in which one of an electromotor driven combustion 
air blowers is preferably flanged laterally to provide a tangential 
combustion air lead. On the right side in FIG. 1, a flame pipe is situated 
that is not represented here, that is surrounded by a heat exchanger. 
Concentrically to the longitudinal axis of the cylindrical casing 1, the 
vaporizer 2 is held in the casing. The vaporizer 2 encloses a cylindrical 
cup shaped body 3 consisting of metal, along whose inner walls a fuel 
evaporator means 4, preferably a fiber packing is arranged. In the 
remaining interior the rod heater plug 6 is situated, that will be held on 
the left side of the casing and is attached by an adapted cable to a 
voltage source. 
A fuel line 5 empties tangentially into the cylindrical body 3. 
Radially, with respect to the cylinder body 3, a high voltage electrode 8 
is arranged that is held on the casing from a support 7, that receives a 
high voltage ignition impulse for the starting of the burners. In the 
combustion chamber 9 a flame itself develops, that warms up the mentioned 
(but not represented in the diagram) heat exchanger for a heated fluid 
carrier or the like. 
For the starting of the vaporizer burner a fuel meter pump that is not 
represented here will be set into motion, so that fuel will be provided 
over the fuel line 5 into the vaporizer. There the fuel spreads itself 
into the fiber packing 4, whereby the vaporizing occurs, sealed from the 
air, by an inserted rod heater plug 6. 
By way of example, with the insertion of the fuel meter pump the combustion 
air blower simultaneously will be inserted, so that the vaporized fuel 
will be sufficiently mixed with combustion air in combustion chamber 9. 
After a certain time an ignition impulse will be given on the high voltage 
electrode 8, so that the mixture will be ignited. 
After the reaching of the operation temperature the rod heater plug 6 will 
be disconnected and the vaporizer remains in thermal equilibrium. 
The fuel delivery will be shut off for a time, disconnection of the burner 
while the combustion air blower can run for an additional period of time, 
in order to burn out the rest of the fuel out of the vaporizer, while the 
rod heater plug can also still be inserted during this smoldering time. 
In a stationary operation, flame control must occur in or on the burner. In 
the arrangement represented in FIG. 1 the flame control happens with the 
help of the high voltage electrode 8, over which the amount of ionization 
of the gases in the area of the high voltage electrode can be determined 
with the help of a voltage meter. FIG. 2 shows a variant of the invention 
that is especially preferred. In FIG. 2, the same sections as in FIG. 1 
are furnished, with appropriate reference marks. The vaporizer 22 is 
formed of a heat pipe 23. The heat pipe 23 has an interior in which the 
rod heater plug 6 is arranged, adjacent an intermediate positioned sieve 
24. A fuel line 25 leads into the area of the outer end of the rod heater 
plug. 
In the area of the combustion chamber the vaporizer possesses a vapor 
outlet 30 on the front of the rod heater plug 6. The steam outlet is a 
flat chamber with more radial openings along to the combustion chamber. 
The effect of the heat pipe 23 is such that the heat energy will be 
transported from left to right in FIG. 2, (that is, towards the warmer 
side). Thereby vaporized fuel is conversed out of the area around rod 
heater plug 6 to the vapor outlet chamber 30, and from there into the 
combustion chamber, in which the vapor will be mixed preferably 
tangentially, with injected combustion air. The ignition here still occurs 
over a high voltage electrode 8 that also makes a precise flame possible. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles.