U.S. patent application number 13/069043 was filed with the patent office on 2011-10-06 for glow plug.
Invention is credited to Martin Allgaier, Martin ELLER.
Application Number | 20110240627 13/069043 |
Document ID | / |
Family ID | 44649965 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110240627 |
Kind Code |
A1 |
ELLER; Martin ; et
al. |
October 6, 2011 |
GLOW PLUG
Abstract
The invention relates to a glow plug comprising a housing, a
glow pencil projecting from the housing, and a supply line which is
enclosed by the housing and connected to the glow pencil. According
to the invention, it is provided that at least one section of the
supply line is formed as a flexible metal tube.
Inventors: |
ELLER; Martin; (Ludwigsburg,
DE) ; Allgaier; Martin; (Ludwigsburg, DE) |
Family ID: |
44649965 |
Appl. No.: |
13/069043 |
Filed: |
March 22, 2011 |
Current U.S.
Class: |
219/267 |
Current CPC
Class: |
F23Q 7/001 20130101 |
Class at
Publication: |
219/267 |
International
Class: |
F23Q 7/22 20060101
F23Q007/22 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2010 |
DE |
10 2010 013 333.7 |
Claims
1. A glow plug, comprising: a housing; a glow pencil projecting
from the housing; and a supply line for connecting the glow pencil
to a voltage source, the supply line being enclosed by the housing
and connected to the glow pencil, wherein at least one section of
the supply line is formed as a flexible metal tube.
2. The glow plug according to claim 1, wherein the flexible metal
tube is comprised of wires.
3. The glow plug according to claim 1, wherein the glow pencil
projects into the flexible tube.
4. The glow plug according to claim 1, wherein the flexible tube is
soldered to the glow pencil.
5. The glow plug according to claim 1, wherein the flexible tube,
at an end facing away from the glow pencil, is connected to a
connecting element.
6. The glow plug according to claim 5, wherein the connecting
element is enclosed by a plastic body.
7. The glow plug according to claim 6, wherein the plastic body is
held non-rotatably in the housing by a form closure.
8. The glow plug according to claim 6, wherein the connecting
element is held non-rotatably in the plastic body by a form
closure.
9. The glow plug according to claim 1, wherein the glow pencil is a
ceramic glow pencil.
10. The glow plug according to claim 1, wherein the flexible metal
tube is enclosed by an insulating tube.
11. The glow plug according to claim 1, wherein the flexible metal
tube bridges a gap between the glow pencil and a connecting
element.
12. The glow plug according to claim 1, wherein the housing is
electrically connected to the glow pencil for providing a ground
connection.
Description
[0001] The present invention aims at showing a way how the
production a glow plug can be simplified.
SUMMARY OF THE INVENTION
[0002] In a glow plug according to the invention, at least one
section of the supply line is formed as a flexible metal tube. This
allows implementing a length compensation element between the glow
pencil and an electrical connection of the glow plug in a
cost-effective manner. A flexible metal tube is able to adjust
flexibly to the length to be bridged and can, therefore, compensate
production-related length differences or changes in length the
occurrence of which during operation is caused by thermal
expansion. For this reason, a flexible metal tube can be used to
replace the contact springs that are usually used as length
compensation element and to simplify production. Furthermore, a
flexible metal tube can be attached to a glow pencil with little
effort by inserting one end of the glow pencil into the flexible
metal tube and soldering it to the latter. In addition, the
flexible metal tube can be easily attached to a connecting element,
for example, by inserting the flexible metal tube into a drilled
hole of a connecting element and crimping it there, said connecting
element being used to connect the glow plug to a voltage
source.
[0003] Preferably, the flexible metal tube consists of wires, more
particularly of metal wires which are interlaced or interwoven with
each other. Flexible tubes consisting of interwoven or interlaced
metal wires are, sometimes, referred to as metal fabric tubes. It
is, for example, also possible to use wrapped tubes in the stead of
metal fabric tubes, said wrapped tubes normally being produced by
wrapping metal foil up onto a mandrel.
[0004] An advantageous further development of the invention
provides that, at its end facing away from the glow pencil, the
flexible tube is connected to a connecting element. Preferably, the
flexible tube is crimped to the connecting element but it can, for
example, also be soldered or welded to the connecting element.
[0005] Another advantageous further development of the invention
provides that the connecting element is enclosed by a plastic body
which electrically insulates the connecting element against the
housing. The plastic body can be injection-molded around the
connecting element in a cost-effective manner.
[0006] Preferably, the connecting element is held non-rotatably in
the plastic body by a form closure. To achieve this, the connecting
element can have projections and/or recesses at an enclosed
section, said projections and/or recesses causing a form closure
with the plastic body. It is particularly advantageous to interlock
the plastic body with the connecting element.
[0007] Preferably, the plastic body is held non-rotatably in the
housing by a form closure. The plastic body can, advantageously, be
pressed into the housing. Since the housing has one or more
projections, more particularly projections that extend in
longitudinal direction, on its inner side, a form closure can also
be generated during pressing-in in addition to a force closure.
Most preferably, the plastic body is interlocked with the
housing.
[0008] Preferably, a glow plug according to the invention has a
ceramic glow pencil, but it can also have a glow pencil that is
made of metal, more particularly of steel. The advantage of a
simple length compensation by means of a flexible metal tube is of
particular importance for ceramic glow pencils because the latter
are breakable.
[0009] In a glow plug according to the invention, the advantage of
a simple length compensation can already be utilized if the
flexible metal tube forms only a section of the electrical supply
line running to the glow pencil. It is, however, preferred that the
flexible metal tube forms the supply line between the glow pencil
and a connecting element at the rear end of the glow plug,
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Further details and advantages of the invention will be
illustrated by means of an exemplary embodiment with reference
being made to the accompanying drawings. In the drawings,
[0011] FIG. 1 is a partially sectional view of an exemplary
embodiment of a glow plug according to the invention; and
[0012] FIG. 2 is an exploded view of the glow plug.
DETAILED DESCRIPTION
[0013] The glow plug shown in FIGS. 1 and 2 comprises a housing 1
with a thread 9 and an external polygon 10, preferably an external
hexagon. A ceramic glow pencil 2 projects from the forward end of
the housing. The glow plug can be connected to a voltage source via
a connecting element 3 which, in the illustrated exemplary
embodiment, projects from the rear end of the housing 1. Ground
connection is achieved via the housing 1.
[0014] The glow pencil 2 is electrically connected to the
connecting element 3 via a supply line which is enclosed by the
housing 1. A special feature of the glow plug shown is that at
least one section of this supply line is formed as a flexible metal
tube 4. The flexible metal tube 4 consists of wires that are
interlaced with each other for which reason it is bendable, with
the result that it can act as a length compensation element between
the glow pencil 2 and the connecting element 3 for compensating
production tolerances or for compensating thermally caused changes
in length.
[0015] The glow pencil 2 is tapered at its rear end and projects
into the flexible metal tube 4 with the tapering section. The
flexible metal tube 4 is soldered to the glow pencil 2, for
example, by means of a solder wrap 5.
[0016] The end of the flexible metal tube 4 that is facing away
from the glow pencil 2 can be connected to a section of the supply
line, for example, by crimping or soldering. Preferably, the
flexible metal tube is inserted into a drilled hole of the
connecting element 3 and is crimped there. However, it is also
possible to push the flexible metal tube onto an appropriately
shaped section of the supply line, for example, a pin-shaped end of
the connecting element 3.
[0017] The flexible metal tube 4 is enclosed by an electrical
insulation 6. The electrical insulation 6 can, for example, be
wrapped around the flexible metal tube 4 as a foil. Preferably, the
insulation 6 is an insulating tube which encloses the flexible
metal tube 4.
[0018] The connecting element 3 is enclosed by a plastic body 7
which is pressed into the housing 1. The plastic body 7 was
produced by injection-molding around the connecting element 3. The
section of the connecting element 3, which is enclosed by the
plastic body 7, has elevations and recesses on its outside, said
elevations and recesses not being shown. The connecting element 3
is, therefore, held non-rotatably in the plastic body 7 by a form
closure. The outer contour of the connecting element 3, which is
enclosed by the plastic body 7, can, for example, be formed as a
series of tooth grooves extending in longitudinal direction, with
the result that the plastic body is interlocked with the connecting
element 3.
[0019] The plastic body 7 can be held non-rotatably in the housing
1 by a similar form closure. To achieve this, fins or other
elevations extending in longitudinal direction are provided on the
inner side of the housing 1, said fins or other elevations cutting
into the plastic body 7 while the latter is being pressed in and
producing a non-rotatable form closure.
[0020] The plastic body 7 is flanged into the housing 1. Therein, a
flange edge 8 of the housing 1 engages around the plastic body
7.
REFERENCE NUMBERS
[0021] 1 Housing [0022] 2 Glow pencil [0023] 3 Connecting element
[0024] 4 Flexible metal tube [0025] 5 Solder wrap [0026] 6
Insulation [0027] 7 Plastic body [0028] 8 Flange edge [0029] 9
Thread [0030] 10 External polygon
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