JPH1073252A - Sheath type glow plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a manufacturing cost inexpensive by a method wherein a connecting unit, having air-tight and heat resistant properties, is constituted of only one seal member. SOLUTION: A ceramic disc 13, exerted as an insulating seal member, closes a glow tube 10 at the opposite side end of a combustion chamber while connection between the glow tube 10 and the ceramic disc 13, exerted as the seal member, as well as connection between a connecting device 12 and the ceramic disc 13, exerted as the seal member, are effected employing friction welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheathed glow plug, which is provided with a glow tube embedded in a metal tubular casing, closed on the combustion chamber side, and filled with insulating powder. The present invention relates to a type in which an electric connection device protruding into a glow tube is arranged in a casing.

[0002]

2. Description of the Related Art In known sheathed-type glow plugs of this type, the casing of the glow plug is provided with a connection device for glow current and a glow tube fixed to the casing. , Closed on the side opposite the casing. In the part of the glow tube that acts as a glow pin, a wire spiral device is provided, which is embedded in an insulating material. The wire helix-shaped device is connected on the one hand to the connection device and on the other hand to the ground via the closed bottom of the glow tube, so that the glow current is transferred from the connection device to the wire helix-shaped device. Through the glow tube and then through the casing to ground. Usually in this case an insulating ring is inserted between the glow tube wall and the connecting device or connecting pin, which ring is
After the hammering process, which brings the glow tube into its final shape and seals the insulating material, it takes on the sealing function.

[0003] Further, a second sealing member is located between the connecting pin and the casing.

[0004]

The object of the invention is therefore to improve a sheath-type glow plug of the type mentioned at the outset, in order to achieve a gas-tight and heat-resistant joint with only one sealing element, and thus to a further improvement. An object of the present invention is to provide a sheath type glow plug whose manufacturing cost is low.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, according to the present invention, a ceramic disk serving as an insulating sealing member closes a glow tube at an end opposite to a combustion chamber. The connection between the glow tube and the ceramic disk acting as a sealing member, and the coupling between the connecting device and the ceramic disk acting as a sealing member are performed by friction welding. I did it.

[0006]

The sheath type glow plug constructed as in the present invention has the following advantages over known ones. Thus, in the sheathed glow plug according to the invention, an airtight and heat-resistant joint is obtained by using only one ceramic disk which is connected to the glow tube and the connecting pin by means of friction welding. And the second
Can be omitted, which is particularly advantageous in terms of cost.

[0007] Further advantageous embodiments of the sheathed-type glow plug according to the invention are described in the dependent claims. Better bonding can be achieved, for example, if an even thinner aluminum disk is provided between the ceramic disk and the glow tube or between the ceramic disk and the connecting pins. The use of aluminum discs in this way has the advantage that both materials bond better during friction welding.

Furthermore, the use of ceramics solves the problem of high temperature loading due to the heat generated by other units in the vehicle, such as, for example, a turbocharger, or the sheathed glow plug itself. The 100% sealing of the joint produced using friction welding guarantees a long service life of the sheathed glow plug. Finally, by reducing the sealing by the sealing ring, which was conventionally required two, to one sealing member, the geometry of the casing is simplified and the number of members is reduced, which is likewise to reduce costs. Useful.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a glow tube 1 in a basic arrangement.
FIG. 4 is a cross-sectional view showing a sheath-type glow plug including a pin 0, a connection pin 12, and a ceramic disk 13; Connection pin 12
Is divided into a portion 12a inside the glow tube and a portion 12b located outside the glow tube. In this case, the connecting pin portion 12a in the glow tube has a larger diameter than the connecting pin portion 12b located outside the glow tube. The ceramic disk 13 has a through hole 14 in the center, and the connection pin 12 extends through the through hole 14. In this case, the diameter of the through hole 14 is smaller than the outer diameter of the connecting pin portion 12a located inside the glow tube and larger than the outer diameter of the connecting pin portion 12b located outside the glow tube. The connection between the glow tube 10, the ceramic disk 13 and the connection pin 12a is performed by friction welding.

FIG. 2 shows one configuration of the coupling type for sealing the glow tube as in FIG. 1, in which the same members as those in FIG. 1 are denoted by the same reference numerals. . In this configuration shown in FIG. 2, a cutout is provided on the side of the ceramic disk 13 facing the glow tube, and an aluminum layer 15 is provided in this cutout. In this case, the aluminum layer 15 is provided in the form of a disk on a ceramic disk by vapor deposition (aufdampfen).
be able to.

Both disc-shaped aluminum layers have the shape of a substantially circular ring, the inner disc having an outer diameter somewhat larger than the outer diameter of the connecting pin 12a. ing. Also, the outer disk has an inner diameter somewhat smaller than the inner diameter of the glow tube 10. This dimensioning results in the ceramic disc having aluminum in the resulting friction weld joint, which results in a better joint between the glow tube and the ceramic or the connecting pin and the ceramic. Will be squeezed. The aluminum layer has previously been placed on the ceramic disc 13
Is advantageously provided. In this case, the aluminum layer may be provided by vapor deposition or an aluminum disk may be mounted. The thickness of the aluminum layer is advantageously between 0.2 and 0.5 mm. Both disks must not be in contact. Otherwise, the insulation of the connecting pins with respect to the glow tube is not guaranteed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a principle configuration of a glow tube connection pin and a ceramic disk.

FIG. 2 shows a second configuration with an additional aluminum disk.

[Explanation of symbols]

10 glow tube, 12 connection pin, 12a, 12b
Part, 13 ceramic disk, 14 through hole,
15 Aluminum layer

Claims (3)

[Claims] 1. A sheath-type glow plug, comprising a glow tube embedded in a metal tubular casing, closed on the combustion chamber side, and filled with an insulating powder. In the type in which the electrical connection device protruding into the glow tube is arranged, a ceramic disk (13) acting as an insulating sealing member places the glow tube (10) on the side opposite to the combustion chamber. Closed at the end of the glow tube (10)
And a ceramic disk (13) acting as a sealing member
And a connection between the connecting device (12) and the ceramic disk (13) acting as a sealing member is performed by friction welding. . 2. The connecting device comprises two parts of different diameters, namely a part inside the glow tube (12a) and a part outside the glow tube (12b), which is located outside the glow tube. The connecting part (12b) has a smaller diameter than the diameter of the part (12a) in the glow tube, so that the connection device has a step and is connected to a ceramic disk acting as a sealing member. 2. The sheathed glow plug according to claim 1, wherein the step is performed at a step of the connection device. 3. The ceramic disk (13) is provided with an aluminum layer, the aluminum layer being used to connect the ceramic disk and the glow tube, which act as a sealing member, to the ceramic disk and the connecting device. The sheath-type glow plug according to claim 1, wherein the sheath-type glow plug is disposed in a region where the portion exists.