Heater having a casing with an integrally cast mounting space for control components

A heater, in particular a vehicle auxiliary heater, of the type which operates with a liquid heat exchange medium and which is tied, for example, into the coolant circuit of a motor vehicle. In this heater, a mounting space for a control device is formed on a jacket-like outer casing, preferably a formation cast integrally as part of the outer casing. In this mounting space, circuit boards and printed circuit cards of the control device and sensor elements are mounted. Heat produced by semiconductor power components of the control device is removed to the surroundings by wall surfaces, in particular side walls, of the mounting space to which they are mounted. An electric connection device is provided that connects the inputs and outputs of the control device to the respective operational parts to be controlled and/or to the vehicle. This electric connection device includes a plug-like base, which preferably is formed of plastic, in which suitable electric conductor parts and contact parts, by which the control device is connected to operational parts to be controlled, are inserted. The control device and/or the electric connection device are designed so that parts projecting on the heater are avoided and a compact design of a heater is achieved.

BACKGROUND OF THE INVENTION 
The invention relates to a heater, in particular a vehicle auxiliary 
heater, which operates with a liquid heat exchange medium that flows 
through a space between a heat exchanger and a jacket-like outer casing, 
and having a control device with inputs and outputs for the essential 
operational parts, such as a combustion air fan, ignition device, flame 
monitor, circulating device for the heat exchange medium, solenoid valve 
in the fuel feed device or the like. 
Heaters or vehicle heaters, which operate with a gaseous heat exchange 
medium, such as air, are known for example from U.S. Pat. No. 3,989,029, 
U.S. Pat. No. 3,989,030, and from German Pat. No. 24 53 202. In these 
heaters, a space projecting above the outer profile of a jacket-like outer 
casing of the heater is provided that can be closed by a cover. In this 
space, which is connected to the induction side of the combustion air fan, 
there is mounted, among other things, an ignition device, such as a spark 
plug or the like, and this space can receive a control unit or a control 
device diagrammatically outlined in these patents. These control units or 
control devices of standard construction have a tightly closed casing The 
inputs and outputs of the control unit or control device are made through 
the casing and are accessible to produce the necessary electric 
connections with the aid of plug-in contacts and electric lines, which are 
then connected to the respective operational parts to be controlled, such 
as a combustion air fan, ignition device, flame monitor, or the like. For 
this purpose, in most cases, individual lines mounted in insulating tubing 
are necessary, and during connection, mix-ups can occur among the 
individual lines to be connected. Furthermore, this manner of connection 
is also expensive and time consuming, so that assembly of electric 
devices, as a whole, is more complicated. Such electric connections, made 
with the aid of plug-in parts and lines, have a tendency to result in 
so-called loose contacts, in which a poor electric connection is present, 
so that disruptions in the control of the heater by the control device can 
occur. 
An approach to solving the problems associated with formation of the 
necessary electrical connections, so that the assembly process will not be 
so time consuming and subject to incorrect terminal connections, is 
presented in copending, commonly assigned, U.S. patent application Ser. 
No. 276,667, filed Nov. 28, 1988. In this application, arrangements for 
providing an electrical connection device for components of heaters are 
disclosed whereby block-shaped plug parts are molded on the lines coming 
from the respective components, and the block-shaped plug parts are 
grouped into a unit upon which a cap having complementary plug parts is 
placed so as to hold the group of plug parts together as a unit upon the 
outer surface of the heater casing. While such devices as disclosed in 
this copending application are effective and beneficial, they provide no 
means for accommodating the mounting of circuit boards, sensors, a control 
unit, or the like. 
SUMMARY OF THE INVENTION 
In view of the foregoing, a primary object of the invention is to provide a 
heater, in particular a vehicle auxiliary heater, of the initially 
mentioned type in which the difficulties described above are overcome, and 
in particular, which enables assembly of the control device and the 
electric connection device connected thereto to be simplified, so that 
disruptive influences due to poor electric connections are also prevented. 
According to a preferred embodiment of the invention, a heater, in 
particular a vehicle auxiliary heater, of the type which operates with a 
heat exchange medium that flows through a space between a heat exchanger 
and a jacket-like outer casing, and which has a control device with inputs 
and outputs for the essential operations parts, such as a combustion air 
fan, ignition device, flame monitor, circulating device for the heat 
exchange medium, solenoid valve in the fuel feed device, and the like, is 
provided with a mounting space for the control device that is formed 
directly on the jacket-like outer casing for mounting circuit boards and 
sensor elements of the control device. 
Therefore, in this heater according to the invention, a control device that 
is mounted in a separate casing of its own need not be provided. Instead, 
the boards that contain the circuits of the control device and the sensor 
elements are mounted directly in the mounting space formed by the 
jacket-like outer casing, so that the control device is integrated into 
the heater and is physically connected directly to the heater. This 
simplifies the assembly of such a heater, since line connections from the 
control device to the heater are eliminated and, in addition, no separate 
place to mount the control device, such as a control unit, is needed, but 
rather the heater forms a compact unit together with the control device. 
Thus, installation costs for installation in a vehicle can also be 
lowered. 
To prevent operational disruptions of the control device that can be caused 
by heat produced by semiconductor power components of the control device, 
the semiconductor power components of the control device are preferably in 
direct heat exchange contact with a wall of the mounting space so that the 
wall of the mounting space is used as a heat sink to remove the heat lost 
by these semiconductor power components. In this way, the inner space in 
which the boards of the control device, etc., are mounted, will not heat 
up during operation of the control device, but rather these electronic 
semiconductor power components are actually cooled. Suitably, the 
semiconductor power components are mounted on side walls of the mounting 
space that stand up from the outer surface of the jacket-like outer 
casing, so that an unimpeded removal of the heat loss of the semiconductor 
power components is possible. 
According to another advantageous embodiment of the invention, the sensor 
elements of the control device, such as a temperature sensor for the heat 
exchange medium, a temperature safety device or the like, are mounted in 
the bottom of the mounting space formed by the jacket-like outer casing. 
In this way, by the special arrangement of the sensor elements, the 
structural construction outlay for their arrangement is simplified and, in 
addition, relatively long line connections to these sensor elements can be 
eliminated. Thus, a compact design of the heater with control device and 
sensors is achieved. Also, the operational reliability is improved by 
this, since the causes of malfunctions that can occur inevitably in 
connection with the line connections and/or plug-in connections are 
avoided. 
To be able to perform a check of the control device in the mounting space, 
if need be, without having to take apart all its parts, for easy access, 
the topside of the mounting space is preferably tightly closed by a 
removable cover. For repair and/or service, the cover can then be removed 
and the parts of the control device can be checked with respect to their 
operational capacity. By tightly closing the cover, surrounding influences 
are prevented from having disadvantageous effects on the operational 
capacity of the control device. 
According to an advantageous feature according to the invention, the 
mounting space for the control device is integrally cast with the 
jacket-like outer casing, so that it is made as one piece with it. In this 
way, no extra steps need to be taken into consideration for providing the 
mounting space since it is taken care of, already, during production of 
the jacket-like outer casing. 
Suitably the inputs and outputs of the control device are combined on one 
side of the mounting space, so that the electric connections to be 
connected to the control device can be configured in a simplified way. In 
this way, installation mistakes during installation of the boards of the 
control device can also be avoided. 
According to another essential aspect according to the invention, a heater 
of this generic type is distinguished in that an electric connection 
device is provided that connects the inputs and outputs of the control 
device to the respective operational parts to be controlled and/or to the 
vehicle. With this design of the heater, the line connections are combined 
with the aid of the electric connection device to reduce the number of 
individual connection lines and the difficulties appearing with them. The 
assembly expense is also reduced and connection mistakes, in particular 
because of mix-ups, can effectively be prevented. 
Preferably, the connection device has a plug-like base that contains 
suitable electric conductor parts and contact parts. These electric 
conductor parts and contact parts, preferably, produce a direct connection 
of inputs and outputs of the control device to the operational parts to be 
controlled, so that plug-in connections susceptible to malfunctions can be 
avoided. Further, the contact closing of the heater with the vehicle and 
the contact closing with the respective essential operational parts of the 
heater and with the control device can be produced in one step using line 
connection paths that are as short as possible and considerably less 
sensitive to disruptions. 
Preferably, the electric conductor parts and contact parts are made of 
metal parts and are inserted in the plug-like base of the electric 
connection device, which, preferably, consists of plastic. 
If need be, to have easy and quick access to the electric conductor parts 
and contact parts, especially for checking, the electric connection device 
is made in two parts, and a tightly sealing removable cover is fastened on 
the plug-like base. In this way, the electric contacts in the electric 
connection device are easily accessible, for example for measuring 
purposes, without having to take the electric connections apart. Further, 
the electric connection elements in the electric connection device 
according to the invention are mounted so as to be effectively protected 
from mechanical effects and negative influences from surrounding 
conditions. In this way, the operational reliability of such a heater can 
be increased considerably. 
According to another advantageous aspect of the preferred embodiment of the 
invention, the electric connection device is mounted, viewed in the axial 
direction of the heater, next to the mounting space for the control device 
and, preferably, the electric connection device is immediately adjacent to 
this mounting space. With such an embodiment, a direct contact closing of 
the inputs and outputs of the control device can be produced by the 
electric conductor parts and contact parts without using individual line 
connections. The connection of the electric connection device leading to 
the vehicle comes from the electric connection device at a central point. 
The electric connection device according to the invention can also form a 
direct plug-in connection with operational parts, such as the ignition 
device and/or the flame monitor. Thus, in this case also, line connections 
susceptible to disruptions can be avoided. Simultaneously, in this way the 
cover-like base of the electric connection device is fixed on a 
predetermined point on the jacket-like outer casing. 
According to another suitable feature according to the invention, the 
electric connection device simultaneously seals an access opening leading 
to the combustion chamber of the heater. Thus, at the same time as the 
electric connection is made with the aid of the electric connection 
device, an access opening to the combustion chamber needed for assembly 
and maintenance purposes is also sealed. 
Further, according to the invention, the electric connection device can be 
designed so that fuses, optionally a back-up fuse and/or electric 
components such as a relay to control external devices, such as a vehicle 
fan or the like, can be mounted. Thus, previously necessary additional 
devices to control external devices can be eliminated, and they are 
combined in the electric connection device in a clear way. 
These and further objects, features and advantages of the present invention 
will become more obvious from the following description when taken in 
connection with the accompanying drawings which show, for purposes of 
illustration only, a single embodiment in accordance with the present 
invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the Figures of the drawings, the same or similar parts are provided with 
the same reference symbols. 
In FIGS. 1 to 3, the heater is designated overall by numberal 1. As an 
example, a vehicle auxiliary heater is shown that operates with a liquid 
exchange medium. Such a heater is, for example, tied into the coolant 
circuit of a motor vehicle. The liquid heat exchange medium flows through 
a space 2 that is formed between a heat exchanger 3 and a jacket-like 
outer casing 4. Heater 1 also has a diagrammatically represented burner 5, 
that projects into a combustion chamber 7 formed by a combustion tube 6. 
The intakes and outputs for the liquid exchange medium are not shown. 
As can be seen, especially from FIG. 2, on the outside of the jacket-like 
outer casing 4 there is formed a mounting space 8, which is, 
advantageously, integrally cast as one part with jacket-like outer casing 
4. The mounting space 8 is bounded by a bottom wall 9 and side walls 10, 
that run essentially perpendicular to bottom wall 9. A control device, 
designated overall by numeral 11 is mounted in mounting space 8. Control 
device 11 includes one or more boards which can be made as printed circuit 
cards and/or which can be equipped with suitable electrical or electronic 
components, as can be seen, especially from FIGS. 1 and 3. Further, the 
control device 11 includes a sensor system comprised of several sensor 
elements 12, 13 that are illustrated in FIGS. 1 and 2 especially by 
cutting out one of the boards of control device 11. Here, for example, a 
temperature sensor 12 for the heat exchange medium flowing in space 2 and 
a temperature safety device 13 are involved. 
The sensor elements 12, 13 are mounted on bottom wall 9 of mounting space 
8. In FIGS. 1 and 2, as an example, a semiconductor power component 14 is 
represented that generates heat (i.e., experiences heat loss) during 
operation. Of course, control device 11 can also include still other 
semiconductor power components. This semiconductor power component 14 is 
mounted on a side wall 10 of mounting space 8 and is in direct 
heat-conducting contact with this side wall 10 (FIG. 1). In this way, the 
heat loss of semiconductor power component 14 can be effectively removed 
and transferred to the surroundings to prevent a heating up of mounting 
space 8 during operation of heater 1 and control device 11. 
The mounting space 8, bounded by side walls 10 and bottom wall 9, is closed 
on top by a cover 15 which, with the interposition of a seal 16, is 
supported on side walls 10 of mounting space 8 and, for example, is 
solidly connected to bottom wall 9 of mounting space 8 by at least one 
screw 17. Thus, control device 11 is mounted in a manner that is 
effectively protected from surrounding influences and, also, from 
externally acting mechanical stresses. By loosening screw 17, cover 15 can 
be removed so that there is direct access to control device 11, if need 
be, for example to eliminate malfunctions. 
As can also be seen from FIGS. 1 and 2, inputs and outputs 18 of control 
device 11 are suitably formed on one side of one of the side walls 10 of 
mounting space 8, so that the necessary electric connections can be 
combined, concentrated, on one side of mounting space 8. 
In connection with FIGS. 2 and 3 of the drawing, further details of an 
electric connection device designated overall by 20 are explained. This 
electric connection device 20 connects inputs and outputs 18 of control 
device 11 to the respective operational parts to be controlled, such as an 
ignition device 21, a flame monitor device 22, a combustion air fan (not 
shown), a solenoid valve for the fuel supply device of heater 1 (also not 
shown), and a circulating pump for the liquid heat exchange medium of 
heater 1 (not shown), etc.. Simultaneously, electric connection device 20 
provides a connection to external devices to be controlled and to the 
vehicle, when heater 1 is installed in a vehicle. 
The electric connection device 20 has a plug-like base 23, which is 
suitably produced of plastic and which, for example, produces a direct 
plug-in contact with ignition device 21 and flame monitor device 22. To 
produce the line connection between the inputs and outputs 18 of the 
control device 11, electric conductor parts and contact parts 24, 
preferably made of metal, are inserted into the plug-like base 23. As can 
be seen especially from FIG. 3, these electric conductor parts and contact 
parts 24 directly contact inputs and outputs 18 of the control device and 
produce the necessary electric connections to the essential operational 
parts to be controlled. It can be further seen from FIG. 3 that electric 
conductor parts and contact parts 24, starting from the inputs and outputs 
18 of control device 11, lead directly to connection parts 25, which are 
suitably made as plug-in connections and to which, advantageously, 
complementary connection parts of a combustion air fan, a solenoid valve, 
a circulating pump or the like can be attached. 
As can be seen diagrammatically from FIG. 2, a cable 26 runs from the 
electric connection device 20. The cable 26 produces an electrical 
connection with the vehicle and/or external devices, such as a vehicle fan 
or the like. The individual electric lines needed for this purpose are 
combined into cable 26. 
In the embodiment of electric connection device 20 explained above, the 
object of simplifying the electrical connections of control device 11 to 
the respective operational parts to be controlled, i.e., to achieve such 
connections in such a way so that as few as possible individual lines are 
susceptible to disruptions. The connections are made in the electric 
connection device 20, mainly, with the aid of electric conductor parts and 
contact parts 24. 
Viewed in the axial direction of heater 1, electric connection device 20 is 
next to mounting space 8 for control device 11 and, preferably, it is 
immediately adjacent to this mounting space 8. In this way, the line 
connection paths are as short as possible and a space-saving and compact 
arrangement of the control device 11 and electric connection device 20 is 
achieved on heater 1. 
Plug-like base 23 seals, in the installed state, an access opening 27 (FIG. 
2) which is open toward combustion chamber 7 and which is used in case of 
servicing and during assembly. That is, parts of burner 11 and other 
devices can be installed or removed through access opening 27 during 
assembly and for servicing. Thus, plug-like base 23 of electric connection 
device 20 is able to serve an additional function as a closure for access 
opening 27. 
Toward the top, plug-like base 23, in which electric conductor parts and 
contact parts 24 are inserted, is closed with the aid of a cover 28, and 
between plug-like base 23 and cover 28 there is mounted a seal 29 to 
guarantee a tight sealing relative to the surroundings. In this way, also, 
the parts of electric connection device 20 are effectively protected from 
mechanical damage. Cover 28 is suitably fastened, with the aid of two 
screws 30, to the jacket-like outer casing 4. When cover 28 is removed 
after loosening screws 30, electric conductor parts and contact parts 24 
in plug-like base 23 are accessible so that checks and/or replacements for 
maintenance purposes can be performed. 
Optionally, plug-like base 23 can merely hold (i.e., store) fuses 31 and 
back-up fuses and/or components, such as, for example, a relay 32 that is 
used to control an external device, such as a vehicle fan (not shown). 
However, these external components can, instead, be connected electrically 
in electric connection device 20, thereby avoiding the use of individual 
lines, as previously customary, for these components. 
Of course, the parts of electric connection device 20 or of control device 
11 can also be provided separately from one another in a heater 1. This 
means that electric connection device 20 can also be designed in the way 
represented if control device 11 is designed, made, or mounted in a way 
other than that of the example represented, and vice versa. However, a 
heater configuration that is especially favorable, from the standpoint of 
compactness, is obtained if the control device 11 and electric connection 
device 20 are made to interact, in a combined way, according to the 
illustrated embodiment. 
While we have shown and described a single embodiment in accordance with 
the present invention, it is understood that the same is not limited 
thereto, but is susceptible of numerous changes and modifications as known 
to those skilled in the art, and we, therefore, do not wish to be limited 
to the details shown and described herein, but intend to cover all such 
changes and modifications as are encompassed by the scope of the appended 
claims.