WO2002001111A1 - Sheathed-element glow plug for a self-igniting internal combustion engine - Google Patents

Abstract

The invention relates to a sheathed-element glow plug for a self-igniting internal combustion engine. The glow plug (1) has a threaded section (3) for connecting said plug (1) to a cylinder head (20). A first sealing element (31) is located at the combustion chamber end of the threaded section (3) and a second sealing element (41, 41`, 41``) is located at the end of the threaded section (3) that lies opposite the combustion chamber. The first sealing element (31) and the second sealing element (41, 41`, 41``) ensure the sealing of the intermediate gap (27) between the internal wall of a continuous bore (22) of the cylinder head and the external wall of the threaded section.

Description

Glow pencil candle for a self-igniting internal combustion engine

State of the art

The invention is based on a glow plug for a self-igniting internal combustion engine according to the type of the first independent claim. Such a glow plug is already known, the glow plug being arranged in a completely through bore in the cylinder head. The glow plug has a housing with a thread, the glow plug being fastened in the bore by means of the thread. The known glow plug has a sealing seat on the combustion chamber end of the housing.

The invention is also based on a system comprising a glow plug and a cylinder head according to the features of the second independent claim, the glow plug being arranged in a completely through bore in the cylinder head. The glow plug has a housing with a thread, the glow plug being fastened in the bore by means of the thread. A sealing seat is arranged at the combustion chamber end of the housing.

The invention is also based on a method for arranging a glow pencil candle in a through Cylinder head completely through bore according to the genus of the third independent claim. It is known to arrange the glow plug into the hole which is completely through the cylinder head, the glow plug being screwed into the hole.

Advantages of the invention

The glow plug according to the invention with the features of the first independent claim has the advantage that no moisture penetrates into the area of the thread with which the glow plug is screwed into the bore. This ensures that glow plugs can be removed without damaging the thread, the cylinder head or the glow plug. An exchange of glow plugs is possible at any time.

Advantageous further developments and improvements of the glow plug candle specified in the first independent claim are possible through the measures listed in the subclaims. It is particularly advantageous and cost-effective to manufacture the first sealing element as a tapered section of the housing. It is also advantageous that a silicone, lacquer and epoxy resin layer is introduced at the end of the first section of the bore remote from the combustion chamber, which layer ensures simple sealing of the bore. It is furthermore advantageous to provide a shaped element at the end of the first section of the bore remote from the combustion chamber, which element consists in particular of a plastic or a metallic material. Such a shaped element is available inexpensively. It is particularly advantageous to design such a shaped element as an O-ring or hose ring, which are particularly inexpensive. The sealing element can be placed particularly advantageously if one also in an outer wall of the glow plug is introduced in the radial direction with respect to the axis of the bore open groove which receives the sealing element attached to the end of the housing remote from the combustion chamber. A displacement of this sealing element during the operation of the internal combustion engine is thus advantageously prevented.

The system according to the invention consisting of a cylinder head and a glow plug with the features of the first independent claim has the advantage that no moisture penetrates into the area of the thread with which the glow plug is screwed into the bore.

The measures listed in the subclaims make advantageous developments and improvements of the system specified in the second independent claim possible from a cylinder head and a glow plug. It is particularly advantageous at the end of the bore remote from the combustion chamber, an expansion which is either cylindrical or conical, into which the sealing element is arranged at the end of the housing remote from the combustion chamber. Simple placement of the sealing element is thus possible. The sealing element can likewise advantageously be arranged in a groove which is open in the radial direction with respect to the axis of the bore and is located at the end of the bore remote from the combustion chamber.

The method according to the invention for arranging a glow plug in a bore completely through a cylinder head with the features of the third independent claim has the advantage over the prior art that only a single additional method step is necessary to prevent moisture from penetrating into the area of the thread to prevent that the glow plug is screwed into the bore of the cylinder head. It is also advantageous that the Installation of the glow plug in the cylinder head has already taken place or has just taken place, so that the sealing element is advantageously optimally adapted to the respective geometries.

The measures listed in the subclaim further improve the method specified in the third independent claim. It is particularly advantageous to use silicone, lacquer or epoxy resin layers, which are advantageously available for this method, when applying or injecting the sealing element during or after the arrangement of the glow plug in the bore.

Further advantages of the method according to the invention for arranging a glow plug in a bore that is completely through a cylinder head, the glow plug and the system comprising a cylinder head and a glow plug can be seen from the following description of exemplary embodiments.

drawing

Embodiments of the invention are shown in the drawings and explained in more detail in the following description. Show it

FIG. 1 shows schematically a glow pencil candle in a view from the side,

FIG. 2a shows a system according to the invention of a cylinder head and a glow pencil candle schematically in cross section,

FIG. 2b shows a section of a system according to the invention of a cylinder head and a glow plug, schematically in cross section, 3 shows a further exemplary embodiment of a system according to the invention comprising a cylinder head and a glow pin candle, schematically in cross section, and FIG. 4 shows a further exemplary embodiment of a system according to the invention comprising a cylinder head and a glow pin candle, likewise schematically in cross section.

Description of the embodiments

Figure 1 shows a glow pencil candle schematically in a view from the side. The glow plug 1 has a metallic housing 3, in the axially extending bore of which a heating element 5 is arranged. The heating element 5 protrudes from the metallic housing 3 at the end on the combustion chamber side. At the end of the metallic housing 3 remote from the combustion chamber, a connection element 7 is arranged. The housing 3, which has the shape of a hollow cylinder, has a sealing seat 31, a thread 33 and a hexagon 35. The sealing seat 31 is designed as a conical, tapering section of the housing 3.

A glow plug 1 is screwed into a through bore of the cylinder head by means of the thread 33 such that the tip of the heating element 5 projects into a combustion chamber of an internal combustion engine. Via a connection connected to the connection element 7, the glow plug 1 is supplied with electrical energy which, at least during the starting phase of the internal combustion engine, causes the tip of the heating element facing the combustion chamber to glow. This heats the combustion chamber and ensures reliable ignition of the fuel / air mixture.

FIG. 2a shows a schematic cross section through a system according to the invention comprising a cylinder head and a glow plug, the glow plug not being cut, but is shown analogously to Figure 1. The cylinder head 20 has a through bore 22 into which the glow plug 1 is arranged. In a preferred embodiment, the glow plug is screwed into the bore 22 by means of the thread 33 of the metallic housing 3, since a section of the bore 22 also contains a thread. The glow plug 1 is screwed into the bore 22 such that the sealing seat 31 of the metallic housing 3 of the glow plug rests on a conically changing cross-section of the bore 22. As already described, the glow plug 1 is arranged in the bore of the cylinder head 20 such that the tip of the heating element 5 projects into the combustion chamber 23. A sealing element 41 is arranged at the combustion chamber end 24 of the bore 22 or at the combustion chamber end of the housing 3 of the glow plug 1, so that the interior 27 of the bore 22 is sealed off from the exterior space 45. This ensures that no moisture can penetrate from the outside space 45 into the area of the thread 33 of the glow plug and thus the glow plug can be removed at any time. The sealing seat 31 and the sealing element 41 ensure that the intermediate space 27 between the inner wall of the through bore 22 and the outer wall of the housing 3 is sealed. The sealing takes place against the outer space 45 and the combustion space 23.

In a preferred exemplary embodiment, the sealing element 41 is designed as a silicone, lacquer or epoxy resin layer. In a further preferred exemplary embodiment, the sealing element is formed by a shaped element which consists of a plastic or a metallic material. A plastic can preferably be an elastomer material. In a further exemplary embodiment, the sealing element 41 is preferably as O-ring or hose ring formed. Such elements are available inexpensively.

A further exemplary embodiment of the system according to the invention comprising a cylinder head 20 and a glow plug 1 is shown schematically in cross section in FIG. 2b. The end 24 of the bore 22 remote from the combustion chamber is shown by the cylinder head 20, in which the glow plug 1 is arranged. The end 24 of the bore 22 remote from the combustion chamber is advantageously designed with a conically tapering cross section which widens in the direction of the outside space 45. The conically extending cross-section of the bore 22 at the end 24 remote from the combustion chamber serves to accommodate the sealing element 41. An arrangement of the sealing element 41 at the correct location is thus ensured.

In a further preferred exemplary embodiment, the cross-section widening at the end 24 of the bore 22 remote from the combustion chamber is designed such that the cross-sectional widening or widening is not conical but rather step-shaped.

In Figure 3, another embodiment of a system according to the invention of a cylinder head 20 and a glow plug 1 is shown schematically in cross section. Here, a further region 25 adjoins the bore 22 which is completely continuous through the cylinder head, which passes into the bore 22 in steps and has a significantly larger cross section than the bore 22. Such a region 25 serves to sink the end of the glow plug 1 away from the combustion chamber into the cylinder head. FIG. 3 also shows that there is a step-like cross-sectional widening at the end 24 of the bore 22 remote from the combustion chamber. Furthermore, a groove 26, hereinafter referred to as first groove 26, is provided at the end 24 remote from the combustion chamber, which is open in the radial direction with respect to the axis of the bore and which receives the sealing element 41. This ensures a precisely predetermined arrangement of the sealing element 41 ^genau , the sealing element 41 being secured against slipping even during operation of the internal combustion engine.

In a further preferred exemplary embodiment, which is shown in FIG. 4, instead of in the side wall of the bore in the side wall of the metallic housing 3 of the glow plug 1, a groove 37 is provided, in which the sealing element 41 ^{, Λ is} arranged. The groove 37, hereinafter referred to as the second groove 37, lies opposite the end 24 of the bore 22 of the cylinder head 20 remote from the combustion chamber and is open in the radial direction with respect to the longitudinal axis of the glow plug. The sealing element 41 ^{, Λ} is thus arranged at a specific, predetermined location on the end 24 of the bore 22 remote from the combustion chamber and is also stationary during the operation of the internal combustion engine.

If the glow plug 1 is now arranged in a bore 22 passing through the cylinder head 20, in a first exemplary embodiment the sealing element 41, 41 ^λ or 41 ^{Λ is} first arranged on the end 24 remote from the combustion chamber before the glow plug 1 with the thread 33 into the bore 22 is screwed in. In this case, the sealing element 41, 41 or 41 ^{, λ} is preferably arranged in a manner described above on the bore at the end 24 of the first section 22 remote from the combustion chamber. In a further preferred exemplary embodiment, the sealing element 41 ^λ or 41 is inserted into the first groove 26 in the inner wall of the bore 22 or the second groove 37 in the outer wall of the housing 3 before the glow plug 1 is screwed in. In a further preferred exemplary embodiment, in order to arrange the glow plug in a bore 22 which passes through the cylinder head 20, the glow plug 1 with the thread 33 is first screwed into the bore 22 and then the sealing element 41 is applied or injected onto the end 24 of the bore 22 remote from the combustion chamber. This application or injection of a sealing compound takes place over the entire circumference of the glow plug 1, so that the inner space 27 between the inner wall of the bore 22 and the outer wall of the housing 3 is completely sealed off from the outer space 45.

By at the combustion chamber-distant end 24 of the housing 3 arranged sealing element 41, 41, 41 ^Λ and arranged at the combustion chamber end of the housing sealing member 31, the interior 27 may be of the housing 3 are effectively sealed between the inner wall of the bore 22 and the outer wall, so that no moisture can penetrate. It is therefore possible at any time to replace glow plugs without damaging the glow plug, the bore or the thread.

Claims

Expectations 1. glow plug for a self-igniting internal combustion engine, the glow plug (1) having a threaded part (3) which is provided for connecting the glow plug (1) to a cylinder head (20), a first at an end of the threaded part (3) on the combustion chamber side Sealing element (31) is arranged and a second sealing element (41, 41 41 ^Λ ) is arranged on an end of the housing (3) remote from the combustion chamber, the first sealing element (31) and the second sealing element (41, 41 41 ^, ) for sealing the Gap (27) between the inner wall of a through hole (22) of the cylinder head (20) and the outer wall of the threaded part (3). 2. Gluhstiftkerze according to claim 1, characterized in that a conical section of the threaded part (3) forms the first sealing element (31). 3. Gluhstiftkerze according to claim 1, characterized in that a silicone, paint or epoxy resin layer forms the second sealing element (41, 41 41 ^{, λ} ). 4. Gluhstiftkerze according to claim 1, characterized in that a shaped element made of a plastic, in particular an elastomer material, or a metallic material forms the sealing element (41, 41 ^Λ , 41 ^Λ> ). 5. Gluhstiftkerze according to claim 4, characterized in that an O-ring or a hose ring forms the shaped element. 6. Gluhstiftkerze according to claim 1, characterized in that the second sealing element (41, 41 41 ^X ) is arranged in a second, open in the radial direction groove (37) in the outer wall of the threaded part (3). 7. System of a glow plug and a cylinder head, the glow plug (1) in a completely through bore (22) of the cylinder head (20) is arranged, the glow plug (1) having a threaded part (3), which is designed to connect the glow plug (1) to a cylinder head (20), with a first sealing element (1) on an end of the threaded part (3) on the combustion chamber side. 31) and a second sealing element (41, 41 ^Λ , 41) is arranged on an end of the housing (3) remote from the combustion chamber, the first sealing element (31) and the second sealing element (41, 41 41 ^, ) for sealing the intermediate space (27) is formed between the inner wall of the through bore (22) and the outer wall of the threaded part (3). 8. System according to claim 7, characterized in that the second sealing element (41, 41 ^Λ , 41 ^λΛ ) is arranged in a first, open in the radial direction groove (26) in the inner wall of the through hole (22). 9. System according to claim 7, characterized in that the second sealing element (41, 41 41 ^N ) is arranged in a conical or step-shaped widening of the through bore (22). 10. A method for arranging a glow plug (1) in a bore (22) which is completely through a cylinder head (20), the glow plug having a metallic housing (3), characterized in that that during or after the arrangement of the glow plug (1) in the through hole (22) at the combustion chamber end (24) of the metallic housing (3) a sealing element (41, 41 ^Λ , 41 ^Λ ) is applied or injected, which seals the space ( 27) between the inner wall of the through bore (22) and the outer wall of the housing (3) from the outer space (45). 11. The method according to claim 10, characterized in that a silicone, lacquer or epoxy resin layer is applied or injected as the sealing element (41, 41, 41 ^Λ ).