Title of Invention

PENCIL-TYPE HEATER PLUG FOR AN INTERNAL COMBUSTION ENGINE

Abstract There is a pencil-type heater plug for an internal combustion engine, with a metalli.c housing (3) which has a longitudinal axis (2) and with a coaxially fUiming connecting bolt (5), an annular sealing element (13) being arranged between the metallic housing (3) and the connecting bolt (5). The sealing element (13) seals off the interior of the metallic housing (3) from the exterior. The sealing element (13) has in each case at least two sealing edges (15, 16 and 15', 16') which come to bear on the inner surface (4) of the metallic housing and on the outer surface (6) of the connecting bolt, respectively.
Full Text

The invention relates to a pencil-type heater plug for an internal combustion engine. A pencil-type heater plug for an internal combustion engine is already known, having a metallic housing and a coaxially running connecting bolt, the interior of the metallic housing being sealed off from the exterior by means of a sealing element. A sealing element of this type is designed, according to the prior art, as an O-ring or as a tubular ring.
Advantages of the invention
By contrast, the advantage of the pencil-type heater plug according to the invention, is that, when a reduction in the pretension in the region of the sealing element occurs due to high temperatures, additional safety is achieved.
Accordingly the present invention provides a pencil-type heater plug for an internal combustion engine, with a metallic housing and with a coaxially running connecting bolt, there being arranged between the metallic housing and the connecting bolt an annular sealing element which seals off the interior of the metallic housing from the exterior, characterized in that the sealing element comes to bear in each case with at least two sealing edges on the inner surface of the metallic housing and on the outer surface of the connecting bolt.
An advantageous development and improvement of the article specified in the main
claim is possible as a result of the measures listed in the subclaims. It is particularly
advantageous that, to form two sealing edges, the sealing element has, in cross
section, first circular regions which are arranged one above the other in pairs. A
sealing element of this type makes it possible to have a linear seal and good adaptation
of the shape of the sealing element to the space between the connecting bolt and the
housing of the pencil-type heater plug. It is advantageous, furthermore, to configure
the cross section of the sealing element in such a way that the latter has two
rectangular regions arranged one above the other. A seal of this kind ensures large-
area sealing by means of two sealing

edges lying one above the other. It is advantageous, at the same time, to round off the corners of the rectangular regions, since material of the seal can thereby be saved. A further saving of material and simpler production can advantageously be achieved by the cross section of the sealing element being formed from two second circular regions arranged one above the other.
Drawing
Exemplary embodiments of the invention are illustrated
in the drawing and are explained in more detail in the
following description. In the drawing,
Figure 1 shows a pencil-type heater plug according to
the invention in longitudinal section, and
Figures 2 to 5 show various embodiments of a sealing
element of a pencil-type heater plug according to the
invention in cross section.
Description of the exemplary embodiments
Figure 1 illustrates a pencil-type heater plug according to the invention diagrammatically in longitudinal section. The pencil-type heater plug has a metallic housing 3 which is radially symmetrical and which possesses a longitudinal axis 2. Arranged coaxially in the metallic housing 3, at the end remote from the combustion space, is a connecting bolt 5 which is connected on the combustion-space side to a heater pencil 7. This heater pencil 7 is likewise arranged coaxially in the metallic housing 3. A pencil-type heater plug of this kind is arranged in an internal combustion engine in such a way that that end of the heater pencil 7 which is on the combustion-space side projects into the combustion space. With the aid of electrical current which arrives at the heater pencil 7 via the connecting bolt 5, that end of the heater pencil 7 which is on the combustion-space side is

heated, so that the necessary temperature for igniting a fuel mixture is reached in the combustion space. The heater pencil illustrated has, furthermore, an insulating disc 9, the connecting bolt 5 being led through the insulating disc 9. The insulating disc 9 is arranged at that end of the metallic housing 3 which is remote from the combustion space, between the metallic housing 3 and the connecting bolt 5, in such a way that the metallic housing 3 and the connecting bolt 5 are electrically insulated from one another. The insulating disc 9 is fixed in position by means of a round nut 11 led over the connecting bolt. At that end of the insulating disc 9 which is on the combustion-space side, the space between the connecting bolt and the metallic housing has located in it a sealing element 13 which is of annular design and which extends over the entire circumference of the connecting bolt. The sealing element 13 seals off the interior of the metallic housing 3 from the exterior. The sealing element 13 has two sealing edges which are arranged one above the other in the direction of the longitudinal axis 2 and which come to bear on the outer surface 6 of the connecting bolt. Furthermore, the sealing element 13 has at least two sealing edges which are arranged one above the other in the direction of the longitudinal axis 2 and which come to bear on the inner surface 4 of the housing. The at least two sealing edges of the sealing element 13 which are arranged one above the other in the direction of the longitudinal axis 2 ensure that, at high temperatures at which the pretension of the components on which the sealing element 13 comes to bear decreases, additional safety is achieved.
An embodiment of a sealing element of a pencil-type heater plug according to the invention is illustrated diagrammatically in cross section in- Figure 2. The cross section of the sealing element 13 has four first circular regions 18 which are arranged next to one

another in pairs. Moreover, the pairs of the first circular regions 18 are arranged one above the other in the direction of the longitudinal axis 2. Thus, a sealing edge is formed on each first circular region 18, specifically, on the pair of first circular regions 18 which is at the top in the drawing, in each case a first sealing edge 15, 15', and, on the pair which is at the bottom in the drawing, in each case a second sealing edge 16, 16' . In this case, the inner sealing edges of the sealing element 15' and 16' come to bear on the outer surface 6 of the connecting bolt 5, and the outer sealing edges 15 and 16 come to bear on the inner surface 4 of the metallic housing 3. Thus, the formation of two sealing edges lying one above the other in the direction of the longitudinal axis 2 is ensured by the sealing element 13, in cross section by four circular regions 18, [lacuna] that double safety for the seal is achieved even when the pretension of the components surrounding the sealing element 13 is reduced as a consequence of temperature.
A further exemplary embodiment of a sealing element 13 of a pencil-type heater plug according to the invention is illustrated diagrammatically in cross section in Figure 3. The cross section of the sealing element 13 is designed, here, in such a way that two rectangular regions 20 are arranged one above the other in the direction of the longitudinal axis. At the same time, in a preferred exemplary embodiment, the corners of the rectangular regions may be rounded off. By virtue of the design of the sealing element 13, as shown in Figure 3, larger-area sealing is achieved by means of each sealing edge 15 and 16. The arrangement of the rectangular regions 20 one above the other ensures that there are two sealing edges which afford additional safety in the event of a reduction in pretension as a consequence of temperature.
In the combination of the exemplary embodiments

illustrated in Figures 2 and 3, the sealing element 13 may be produced in the way illustrated in Figure 4. In Figure 4, once again, the cross section of a sealing element of a pencil-type heater plug according to the invention is illustrated diagrammatically. In this case, two first circular regions 18 are arranged next to one another and above these two first circular regions 18 is arranged a rectangular region 20. In a preferred exemplary embodiment, the corners of the rectangular region 20 are rounded off. A combination of a linear and a large-area seal can thus be achieved. The sealing element 13 may also be designed in such a way that the two first circular regions 18 are arranged above the rectangular region 20.
Figure 5 illustrates a further exemplary embodiment of a sealing element 13 of a pencil-type heater plug according to the invention diagrammatically in cross section. In this case, two second circular regions 2 3 are arranged one above the other in the direction of the longitudinal axis. Every second circular region 23 has laterally, on the inside (given the reference symbols 15' and 16') and on the outside (given the reference symbols 15 and 16) , sealing edges which make it possible to seal off the interior of the metallic housing 3 in relation to the exterior. In this case, the inner sealing edges 15' and 16' come to bear on the outer surface 6 of the connecting bolt 5 and the outer sealing edges 15 and 16 come to bear on the inner surface 4 of the metallic housing 3. The sealing element 13, designed as illustrated in Figure 5, has, in a particularly simple embodiment, two sealing edges on the inside and on the outside, which are arranged one above the other in the direction of the longitudinal axis 2 and which afford additional safety in the event of a reduction in pretension as a consequence of temperature.
In a further preferred exemplary embodiment, the

sealing element 13 may also be designed in such a way that it have [sic] more than two sealing edges which lie one above the other in the direction of the longitudinal axis and which in each case come to bear on the inner surface 4 of the metallic housing 3 and on the outer surface 6 of the connecting bolt 5. A sealing element of this kind may have, in addition to the cross-sectional regions described with reference to Figures 2 to 5, further pairs of first circular regions 18 or rectangular regions 20 or second circular regions 23 which are arranged, in the direction of the longitudinal axis 2, above or below the cross-sectional regions illustrated in Figures 2 to 5.
In a further preferred exemplary embodiment, the sealing element 13 may also be designed in such a way that, as illustrated in Figure 6, the at least two sealing edges 15, 16 and 15', 16' lying one above the other are displaced in relation to one another in [sic] perpendicularly to the direction of the longitudinal axis 2. This means that th'e sealing edge 15 is displaced outwards in relation to the sealing edge 16, with respect to the direction perpendicular to the longitudinal axis 2. The sealing edge 15' is similarly displaced inwards in relation to the sealing edge 16' . However, the sealing edges 15 and 16 or 15' and 16' are still arranged one above the other. This is achieved in that the rectangular region 20 which forms the sealing edges 15 and 15' has a greater extent in the direction perpendicular to the longitudinal axis than the rectangular region which forms the sealing edges 16 and 16' . Thus, the rectangular region 20 which forms the sealing edges 15 and 15' has a larger area than the rectangular region 20 which forms the sealing edges 16 and 16'. A formation of sealing edges 15 and 16 or 15' and 16' displaced in relation to one another perpendicularly to the longitudinal axis may also be achieved in a similar way with first and second circular regions or with a combination of rectangular

regions and of first or second circular regions.



WE CLAIM :
1. Pencil-type heater plug for an internal combustion engine, with a metallic
housing (3) and with a coaxially running connecting bolt (5), there being arranged
between the metallic housing (3) and the connecting bolt (5) an annular sealing
element (13) which seals off the interior of the metallic housing (3) from the exterior,
characterized in that the sealing element (13) comes to bear in each case with at least
two sealing edges (15, 16 and 15', 16') on the inner surface (4) of the metallic housing
and on the outer surface (6) of the connecting bolt.
2. Pencil-type heater plug as claimed in claim 1, wherein, to form the at least two sealing edges (15, 16 and 15', 16'), the sealing element (13) has, in cross section, at least four first circular regions (18) arranged one above the other in pairs in the direction of a longitudinal axis (2) of the metallic housing.
3. Pencil-type heater plug as claimed in claim 1, wherein, to form the at least two sealing edges (15, 16 and 15', 16'), the sealing element (13) has, in cross section, at least two rectangular regions (20) arranged one above the other in the direction of a longitudinal axis (2) of the metallic housing.
4. Pencil-type heater plug as claimed in claim 1, wherein, to form the at least two sealing edges (15, 16 and 15', 16'), the sealing element (13) has, in cross section, at least two first circular regions (18) arranged next to one another in pairs and at least one rectangular region (20), the at least two first circular regions (18) arranged next to one another in pairs and the at least one rectangular region (20) being arranged one above the other in the direction of a longitudinal axis (2) of the metallic housing.

5. Pencil-type heater plug as claimed in claim 3 or 4, wherein the rectangular
regions (20) have rounded-off corners.
6. Pencil-type heater plug as claimed in claim 1, wherein, to form the at least
two sealing edges (15, 16 and 15', 16'), the sealing element (13) has, in cross section,
at least two second circular regions (23) arranged one above the other in the direction
of a longitudinal axis (2) of the metallic housing.
7. Pencil-type heater plug for an internal combustion engine, substantially as
hereinabove described and illustrated with reference to the accompanying drawings.


Documents:

in-pct-2002-che-1455-abstract.pdf

in-pct-2002-che-1455-claims duplicate.pdf

in-pct-2002-che-1455-claims original.pdf

in-pct-2002-che-1455-correspondance others.pdf

in-pct-2002-che-1455-correspondance po.pdf

in-pct-2002-che-1455-description complete duplicate.pdf

in-pct-2002-che-1455-description complete original.pdf

in-pct-2002-che-1455-drawings.pdf

in-pct-2002-che-1455-form 1.pdf

in-pct-2002-che-1455-form 26.pdf

in-pct-2002-che-1455-form 3.pdf

in-pct-2002-che-1455-form 5.pdf

in-pct-2002-che-1455-other documents.pdf

in-pct-2002-che-1455-pct.pdf


Patent Number 205898
Indian Patent Application Number IN/PCT/2002/1455/CHE
PG Journal Number 26/2007
Publication Date 29-Jun-2007
Grant Date 12-Apr-2007
Date of Filing 13-Sep-2002
Name of Patentee ROBERT BOSCH GMBH
Applicant Address Postfach 30 02 20 70442 Stuttgart
Inventors:
# Inventor's Name Inventor's Address
1 CARBON, Steffen Dorothea-Schlegel-Weg 8 73614 Schorndorf
2 KERN, Christoph Wilhelmstrasse 5 71546 Aspach
PCT International Classification Number F23Q7/00
PCT International Application Number PCT/DE2001/000198
PCT International Filing date 2001-01-18
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 100 12 266.3 2000-03-14 Germany