Abstract:
A combustion chamber assembly, especially for a vehicle heater, includes a combustion chamber housing ( 12 ) with a housing wall ( 16 ) surrounding a combustion chamber. At least one ignition element opening ( 28 ) is provided in the area of the housing wall ( 16 ) and an ignition element ( 30 ) is fixed in a fastening area ( 44 ) in at least one ignition element opening ( 28 ). The at least one ignition element opening ( 28 ) is designed with a circular wedge inner profile ( 54 ) and the fastening area of the ignition element fastened in this opening is designed with a circular wedge outer profile and fasteningly meshes with the circular wedge inner profile ( 54 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2010 043 222.9 filed Nov. 2, 2010, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to a combustion chamber assembly, especially a vehicle heater, comprising a combustion chamber housing with a housing wall surrounding a combustion chamber, wherein at least one ignition element opening is provided in the area of the housing wall and an ignition element with a fastening area is fixed in at least one ignition element opening. 
     BACKGROUND OF THE INVENTION 
     Such a combustion chamber assembly, known from DE 10 2005 055 642 A1, is shown in  FIG. 1 . The combustion chamber assembly  110  comprises a combustion chamber housing  112  with a housing wall  116  surrounding a combustion chamber  114 . This housing wall  116  comprises an approximately cylindrically shaped circumferential wall  118  and a bottom wall. The circumferential wall  118  and the bottom wall  120  may be provided as an integrally designed, pot-shaped component, but they may also be provided as separate areas or assemblies and connected to one another. 
     An ignition element mounting attachment  122  is provided at the circumferential wall  118 . This mounting attachment  122  is open in the area of a first end  124  towards the combustion chamber  114  formed in the combustion chamber housing  112 . At an end  126  of the mounting attachment  122 , away from the circumferential wall  118 , the ignition element mounting attachment  122  carries an ignition element  130  extending in the ignition element opening  128  formed in the ignition element mounting attachment  122 , for example, a glow plug. 
     The inner surface of the circumferential wall  118  and also the inner surface of the ignition element mounting attachment  122  are lined with a porous evaporator medium  132  and  134 , respectively. The porous evaporator medium  134  of the ignition element mounting attachment  122  and the porous evaporator medium  132  of the circumferential wall  118  are in connection with one another in the area of an opening  136 , in the area of which the ignition element opening  128  of the ignition element mounting attachment  120  is open towards the combustion chamber  114 . A fuel feed line  138  feeds liquid fuel in the area of the ignition element mounting attachment  122  into the porous evaporator medium  134  provided there. The liquid fuel is distributed in the inner volume area of this porous evaporator medium  134  under capillary delivery action and also under the force of gravity and it also enters the porous evaporator medium  132 . Fuel can be discharged for combustion with combustion air at the surfaces of the porous evaporator media  132 ,  134 , which surfaces are exposed to the ignition element opening  128  or to the combustion chamber  114 . To feed this combustion air, a combustion air feed opening  140 , opposite which, for example, a passage opening  142  may be located in the porous evaporator medium  134 , is provided, for example, in the ignition element mounting attachment  122 . A plurality of such openings  140  and  142 , respectively, may, of course, also be provided here. It is also possible to provide additional combustion air inlet openings in the housing wall, i.e., in the circumferential wall  118  and/or bottom wall  120 . 
     In an end area located at the end  126  of the ignition element mounting attachment  122 , the ignition element  130  has a fastening area  144 . This is fixed in the ignition element mounting attachment  122  or at the end  126  thereof, for example, by a screw connection. Starting from the fastening area  144 , an ignition area  146  extends in the ignition element opening  128  stretched out long in the ignition element mounting attachment  122 . An electric connection line  148 , via which the electric current necessary for exciting a glow coil, which is provided in the ignition area  146  and is indicated in  FIG. 1 , can be fed, extends from the fastening area  144  outside the ignition element mounting attachment  122 . 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a combustion chamber assembly, especially for a vehicle heater, in which stable fastening of at least one ignition element at a combustion chamber housing is nevertheless achieved despite a simplified design. 
     This object is accomplished according to the present invention by a combustion chamber assembly, especially for a vehicle heater, comprising a combustion chamber housing with a housing wall surrounding a combustion chamber, wherein at least one ignition element opening is provided in the area of the housing wall and an ignition element with a fastening area is fixed in at least one ignition element opening. 
     Provisions are made, furthermore, for at least one ignition element opening to be designed with a circular wedge inner profile and the fastening area of the ignition element fastened in this ignition element opening is designed with a circular wedge outer profile and it fasteningly meshes with the circular wedge inner profile. 
     The fastening of at least one ignition element in an ignition element opening is achieved in the design by the cooperation of two complementary circular wedge profiles. These can be manufactured in a markedly simpler manner than, for example, threaded formations. However, based on the self-locking fastening action of such circular wedge profiles, stable fixation is guaranteed, which also cannot be detached by vibrations. It is nevertheless possible to detach the two circular wedge profiles meshing with one another in a fastening manner by acting on them by means of a tool, for example, in order to perform maintenance or to replace a defective ignition element. 
     At least one ignition element opening, especially an ignition element opening in the area of which an ignition element is fastened, may be provided in the area of a circumferential wall of the housing wall. 
     To create favorable ignition conditions comparatively rapidly especially during a start phase, i.e., at the beginning of the combustion, provisions are made, furthermore, for providing an ignition element mounting attachment open towards the combustion chamber at the housing wall and for an ignition element opening to be formed in at least one ignition element mounting attachment. 
     It is advantageous in respect to the ignition conditions, on the one hand, and the easiest possible embodiment, on the other hand, if the at least one ignition element mounting attachment is designed with a circular wedge inner profile at least in its end area located away from the housing wall. 
     It is advantageous, especially during the start phase of the combustion, if the combustion air necessary for the combustion is introduced in an area close to the ignition element. Provisions may, furthermore, be made for this for forming at least one combustion air inlet opening between a circular wedge inner profile and a circular wedge outer profile that fasteningly meshes with same. Consequently, the openings present in the fastened state in the complementary circular wedge profiles that fasteningly mesh with one another are also used according to the present invention to introduce combustion air at the same time. Thus, it is not necessary to seal openings by additional constructional measures. 
     The present invention pertains, furthermore, to an ignition element, which can be used, for example, in the combustion chamber assembly according to the present invention, comprising a fastening area and an ignition area, wherein a circular wedge outer profile is provided at the fastening area. 
     The design may be such that the fastening area forms an end area of the ignition element and the ignition area extends beginning from the fastening area. 
     Furthermore, the present invention pertains to a vehicle heater, comprising a combustion chamber assembly according to the present invention and/or at least one ignition element according to the present invention. 
     The present invention will be described below in detail with reference to the figures attached. 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a sectional view of a combustion chamber assembly with an ignition element; 
         FIG. 2  is a perspective view of a combustion chamber assembly or of a combustion chamber housing therefor; 
         FIG. 3  is a perspective view of an ignition element for the combustion chamber assembly shown in  FIG. 2 ; and 
         FIG. 4  is a view of the ignition element shown in  FIG. 3  in direction of view IV in  FIG. 3  in connection with a section of an ignition element mounting attachment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular,  FIG. 2  shows a combustion chamber assembly  10  designed according to the present invention or a housing  12  therefor. The housing wall  16  with the circumferential wall  18  and with the bottom wall  20  is recognized, at which blade-like combustion air guiding elements  50  are provided in the exemplary embodiment being shown to generate an active flow admission in the combustion air to be introduced into the combustion chamber not recognizable in  FIG. 2 . 
     Furthermore, the ignition element mounting attachment  22 , which extends approximately tangentially from the circumferential wall  18  and which is open at its end  26  located in front of the circumferential wall  18  is seen. A lateral connecting branch  52  branches off from the ignition element mounting attachment  22 . The fuel feed line  138  shown in  FIG. 1  in the state of the art may open into this connecting branch  52 . 
     The internal structure of the combustion chamber housing  12  in  FIG. 2  may correspond to the internal structure of the combustion chamber housing  12  that is described above with reference to  FIG. 1 , so that reference is made to the descriptions given above. 
     The ignition element mounting opening  28  of the ignition element mounting attachment  22 , which said mounting opening can be recognized in  FIG. 2 , is provided with a circular wedge inner profile  54  in the area of end  26 . This inner profile  54  comprises a plurality of ramp areas  56 , which extend in an approximately circular pattern around a central longitudinal axis L 1 , and which pass over into one another at respective step areas  58  to provide the circular wedge inner profile. Such a ramp area can be characterized, for example, in that its distance of a surface to the central longitudinal axis L 1  decreases, for example, continuously beginning from the abrupt or stepped distance reduction generated at a respective step area  58  until an abrupt or stepped reduction of the distance to the central longitudinal axis L 1  occurs again at the step area  58  following next in the circumferential direction. 
       FIG. 3  shows an ignition element  30  to be mounted in the ignition element mounting attachment  22 . This ignition element  30  comprises a fastening area generally designated by  44  and an ignition area  46 , which extends in the ignition element mounting opening  28  along the ignition element mounting attachment  22 , and in which, for example, an electrically excitable glow coil may be provided. A contact terminal area  62  may be provided for the electrical contacting on the side of the fastening area  44 , which said side is the opposite side relative to the ignition area  46 . Fastening area  44  is provided with a circular wedge outer profile  64  complementary to the circular wedge inner profile  54 . This circular wedge outer profile  64  also comprises a plurality of ramp areas  66 , three in the example being shown, which pass over into each other in respective step areas  68 . The circular wedge outer profile  64  with its ramp areas  66  extends approximately circularly around a central longitudinal axis L 2  of the ignition element  30  here as well, which said central longitudinal axis essentially coincides with the central longitudinal axis L 1  thereof in a state in which the ignition element  60  is mounted in the ignition element mounting attachment  22 . The ramp areas  66  are also characterized in this circular wedge outer profile, for example, in that, beginning from an abrupt or stepped increase in the distance of an outer surface to the central longitudinal direction L 2 , this distance will then decrease, for example, continuously in the circumferential direction until an abrupt or stepped increase in the distance of the outer circumferential surface occurs again at the step area  68  following next in the circumferential direction. 
     Due to the complementary design of the two circular wedge profiles  54 ,  64 , which pertains to both the dimensioning and the number of respective ramp and step areas, it is possible to push these two circular wedge profiles  54 ,  64  into one another in the direction of the central longitudinal axis L 1 , and the ignition area  46  will then dip into the ignition element mounting attachment  22 . If the two circular wedge profiles  54 ,  64  are aligned with one another in the axial direction as well, the ignition element  30  is rotated in the ignition element mounting opening  28 , namely, counterclockwise in the view in  FIGS. 2 and 3 , by a tool acting, for example, at a hexagonally designed tool action formation  70 . This causes the step areas  58 ,  68 , which are at first still located very close opposite each other in the pushed-in state, to move away from each other and to wedge the ramp areas  54 ,  64 , which are located radially opposite each other in relation to one another. The state recognizable in  FIG. 4  is now generated, in which openings  72  are formed between step areas  58 ,  68  located directly opposite each other in the circumferential direction and the ramp areas  56 ,  66  starting from and adjoining same. These openings are open towards both the inner volume area of the ignition element mounting attachment  22  and the ignition element mounting opening  28 , i.e., they are also open towards the outside. These openings  72 , which are likewise distributed uniformly over the circumference especially in case of the uniform circumferential distribution of the ramp areas and of the step areas at the two circular wedge profiles, make possible the entry of combustion air into the ignition element mounting attachment, doing so in a uniformly distributed manner over the circumference around the central longitudinal axis L 1 . It can thus become unnecessary to provide additional openings in the ignition element mounting attachment  22  itself, which would have to be prepared, for example, by drilling. 
     Consequently, locking of an ignition element at a combustion chamber housing, at an ignition element mounting attachment thereof in the example being shown, is generated in the design according to the present invention in a simple manner in terms of design by circular wedge profiles that can be brought into a self-locking wedged action with one another by rotating an ignition element. This makes it unnecessary to insert a thread into the ignition element mounting attachment or the combustion chamber housing. The circular wedge inner profile at the ignition element mounting attachment can be formed integrally during the manufacture of the combustion chamber housing, for example, in a casting or diecasting process. Based on the self-locking locking, there is actually no risk of detachment of the ignition element. It is necessary for this to act on the ignition element with a corresponding tool and to detach same. This also simplifies the process of replacing, e.g., a defective ignition element. 
     It shall be pointed out that the principles of the present invention may, of course, also be applied if the ignition element opening is not provided in an ignition element mounting attachment but, for example, directly in the circumferential wall or the bottom wall of the combustion chamber housing. A circular wedge inner profile could be provided there as well in an opening, for example, one formed in a casting operation. It shall also be pointed out that a combustion chamber housing as it is shown in  FIG. 2  may, of course, also have more than one ignition element mounting attachment, for example, two or more ignition element mounting attachments, which may now have, if desired, the same design, i.e., they all may be provided with the circular wedge inner profile. 
     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.