EP3204693A1

EP3204693A1 - Heating element for an electrically heatable sheathed glow plug, comprising an axially pressed heating insert, and associated manufacturing method

Info

Publication number: EP3204693A1
Application number: EP15775109.0A
Authority: EP
Inventors: Bruno CERON NICOLAT
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-10-07
Filing date: 2015-09-11
Publication date: 2017-08-16
Also published as: CN106796030A; CN106796030B; WO2016055233A1; DE102014220235A1

Abstract

The invention relates to a heating element (1) for an electrically heatable sheathed glow plug, comprising a glow tube (11) and a heating insert (12) which is disposed in the glow tube (11) and includes at least one coil (121) and an insulating powder (122) that is pressed together with the coil; the heating insert (12) is an axially pressed part. The invention further relates to a method for manufacturing a heating element (1) for an electrically heatable sheathed glow plug.

Description

Radiator for an electrically heated glow plug with axially pressed

Heating insert, and associated manufacturing process

PRIOR ART The invention relates to a radiator for an electrically heatable glow plug or glow plug, and more particularly to a glow plug radiator with a heating insert provided therein, wherein the heating insert consists of at least one helix and insulating powder acting as an electrical resistance element. Furthermore, the invention relates to a production method of such a radiator according to the invention for an electrically heatable

Glow plug.

Known glow plugs currently come not only as a cold-start aid in a chamber of an internal combustion engine, such as a pre-vortex or combustion chamber of a luftverdichtenden, self-igniting diesel engine

Application, but also in other applications, such as fuel heaters in a common-rail injection system of a flexible-fuel propulsion system, as a cold start aid when starting kerosene-powered gas turbines and oil heaters, or the like. As a cold-start aid in known motor vehicles with diesel engines, which have a higher efficiency compared to gasoline-powered internal combustion engines, they specifically support the starting process at a

Cold start, as in this problem-free auto-ignition of the injected diesel fuel is usually not possible. Even after the start, it often makes sense to provide a heat source in the form of glow plugs to improve a cold run of the engine and its exhaust emissions, with different fuel qualities can reduce the ignitability of the compressed air / diesel mixture. In contrast, in modern motor vehicles with alternative drive systems, such as

Motor vehicles with flexible-fuel drives, that is, drive systems with Gasoline, the alcohols methanol and ethanol and any mixtures of these three fuels can be operated at low temperatures, igniting the ignition of the fuel, with a heating of the

Fuel in the respective common rail injection system by a

Glow plug is beneficial.

In order to counteract the above problems, usually located in the combustion chambers of a diesel engine or in the common rail injection system of flexible-fuel motor vehicles in each case at least one electrically heatable glow plug, also called GLP (from the English term "glow plug"), By means of which the diesel engine is preheated in the starting phase or the alcohol fuel is heated during operation of the flexible fuel drive system, the glow plugs used usually have a helix acting as an electrical resistance element, which consists either of two interconnected helical parts of different materials consists, that is, from a heating coil and a control coil connected to this, or consists of a single coil, a so-called Monowendel, which combines the properties of a control and a heating coil in a single coil.

An example of a glow plug with a heating filament portion 91 1 and control coil portion 912 existing helix 91, as shown in Figure 8, is known for example from Bosch as a so-called Duratherm-Chromium glow plug. The glow plug 9 shown therein consists of the coil 91, which is disposed within a metal glow tube 92, wherein the

Glow tube 92 is held in a housing 93. The helix 91 is embedded within the glow tube 92 in electrically insulating but heat-conductive filling powder 94. One end of the helix 91, that is, one end of the helix

Heizwendelabschnitts 91 1, is connected to the inside of an exposed tip of the glow tube 92, wherein the glow tube 92 may also be referred to as glow plug or heating pin. The other end of the coil 91, that is, an end of the control coil portion 912 is connected to a terminal bolt 95, wherein the connection of the connecting bolt 95 with the coil 91 the

Plus contact of the glow plug 9 represents. The negative contact of the coil 91 is via the glow tube 92 and on via the housing 93 to the engine block educated. The connecting bolt 95 is held opposite the glow tube 92 by an electrically insulating glow tube seal 96 and with respect to the housing 93 with an electrically insulating housing seal 97. Further, a round plug 98 is arranged at the free end of the connecting bolt 93 for electrically contacting the positive contact of the coil 91, wherein a

Insulating washer 99 is provided for electrical insulation between round plug 98 and housing 93. The helix 91, the glow tube 92, the insulating powder 94, the terminal bolt 95 and the glow tube seal 96 thereby constitute a so-called radiator of the glow plug, also referred to as a heater or glow plug.

In the previously described conventional construction of a metal glow plug 9 ("m-GLP"), the coil 91 is first inserted into the glow tube 92, connected thereto, for example, by welding, then the glow tube 92 with the thermally conductive and electrically insulating

Filling powder 94 filled, sealed and by a so-called

Round kneading processes processed to a certain extent. The rotary kneading is performed mainly for compressing the interior of the glow tube 92 to ensure good heat conduction from the coil 91 to the outer surface of the glow tube 92. In the taking place by the swaging

Compression process, however, the helix 91 is heavily deformed. When using highly ductile metals or metal alloys, such as iron or nickel alloys, for the helix 91, however, the

Helix wire diameter increase and the original round cross section of the helix 91 is correspondingly oval. In the case of a hard and rather ductile

Material for the coil 91, such as refractory metals such as tungsten and molybdenum, the deformation is even more pronounced by the rotary kneading, although the coil wire diameter hardly changes, but the coil 91 is bent along its wire axis. The rotary kneading, that is, the resulting deformation of the spiral wire can be too short

Windings of the coil 91, short circuits between glow tube 92 and coil 91, damage to the helical wire in the form of cracks, and the like lead. In any case, thereby worsen the electrical properties of the coil 91 and consequently the function and quality of the glow plug 9 considerably. Disclosure of the invention

To solve the above-described problem of the prior art, a radiator for an electrically heated glow plug with the

Characteristics of claim 1, a glow plug with the features of claim 4 and a corresponding manufacturing method with the

Characteristics of claim 5 proposed. Advantageous developments of the invention are characterized by the features of the dependent claims.

More specifically, it is an aspect of the present invention to provide a radiator of an electrically heatable glow plug having a glow tube and arranged in the glow tube heating insert, which consists of at least one coil, also referred to as incandescent, and a thus pressed insulating powder, wherein the Heating insert is an axially pressed component. An axially pressed component, also referred to as an axially pressed component, is to be understood as a component made up of different components which are connected to one another by means of at least one pressing tool by means of a pressing or compacting operation carried out in the axial direction of the pressed component such that the pressed component retains its component retains final shape and how a brittle material can be handled. Such a pressing tool usually consists of two

Press punches, also called press punches, which are to be pressed

Apply components with a compressive force, usually holding a mold to be pressed components. Under certain circumstances, the mold can also be part of an assembly in which the final pressed component is to remain inserted. The resulting heating insert, which consists of at least the helix and the compacted insulating powder after pressing, can also be referred to as a helix compact powder composite.

The glow tube is in the radiator according to the invention usually a one-sided closed, tubular member which may be formed either as a separate part, which may be held in a housing of the glow plug may, or sometimes may be formed as part of the housing of the glow plug.

The glow tube may consist of a corresponding metal, preferably of a high temperature metal alloy such as a

Nickel alloy. The helix as an internal heating conductor is in

Embedded insulating powder, wherein the helix is either a so-called

Einstoffwendel or Monowendel is that combines the heating and regulating function, or is a so-called two-substance coil, which consists of at least two interconnected coil parts made of different materials, that is, a heating coil and connected to this control coil. For the materials of a two-material coil usually come as

Standard helix material ferrous alloys, for example CoFe8, or nickel alloys are used in conjunction with Heizleiterlegierungen such as the iron alloy CrAI 25 5 with 70% iron content. When

Rule coil material may alternatively be used molybdenum or tungsten. The positive pole is formed by a first end of the helix, and the negative pole takes place by a connection of the second end of the helix with the glow tube, which is connected via the preferably metallic housing of the glow plug with the engine block as a ground connection. It can still be a receiving part between the glow tube and the

Be provided housing the glow plug. With respect to the insulating powder, it is preferable that the insulating powder of the heating body of the present invention has a thermal expansion coefficient at least similar to that of the material of the surrounding coil in size and temperature characteristics. As is known, inter alia, from DE 27 46 595 A1, when using molybdenum or tungsten as a helical material, the insulating powder may preferably consist of magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), silicon nitride, boron nitride, silicon carbide or aluminum nitride.

According to a preferred embodiment of the radiator according to the invention, the heating insert may further comprise a powder compact, which is arranged in an inner cavity of the coil, that is, in the surrounding by the preferably helical coil cavity or

Spiral core around which wind the turns of the coil, wherein Preferably, the insulating powder and the powder compact consist of different powder materials or wherein the insulating powder and the powder compact consist of the same powder material with different particle sizes. It can be used as a material alumina inside the coil and

Magnesium oxide in the remaining cavities such as between the

Turns of the helix and between helix and glow tube are used. An advantage is to provide a worse heat conduction to the inside than to the outside and thus to achieve a significantly improved heating speed and power consumption of the glow plug. A powder compact is understood to mean a component pressed from powder, which can then be handled as a powder composite in the form of a single component. This has the advantage in the present invention that a powder compact can be inserted into the helix and then pressed together with the helix and the insulating powder during the pressing process, without the powder of the powder compact mixed with the insulating powder before pressing.

According to a preferred embodiment of the radiator according to the invention, the helix of the heating element is electrically connected to the glow tube. More specifically, the coil of the heating insert, at least partially from the

Heating insert is exposed and the negative pole or negative contact of the coil forms, with an inner side of the glow tube to the closed, exposed from the housing end materially connected, preferably by welding or soldering. When pressing the heating insert in the glow tube, the helix can be materially connected to the glow tube before pressing the heating element.

According to another aspect of the present invention, there is further provided a glow plug having such a heater. As further components of such a glow plug with the

heater according to the invention, this, as already known from the above-mentioned prior art, including a housing, electrically insulating housing seals that isolate the terminal bolt relative to the housing, a round plug, which at the exposed end of the

Connecting bolt is provided, and have an insulating, the electrical insulation between round plug and housing is provided. In the glow plug, the connection bolt may be in electrical contact with a second end of the coil, which is opposite to the first end of the coil connected to the glow tube and forms the plus pole or positive contact of the coil, for example by screwing on, press-fitting or a similar method , It is also conceivable to provide an electrically conductive compression component between the coil and the connecting bolt, which facilitates an electrical connection between these components.

According to a further aspect of the present invention, a method is provided for producing a heating element of an electrically heatable glow plug, in particular for producing a heating element as described above, the method according to the invention comprising the following steps in this order:

a step of forming a coil so as to have a predetermined shape after a subsequent step of axially pressing, that is, a shape having at least a certain spiral diameter and with certain intervals between the individual turns;

a step of providing and centering at least the helix using a centering aid;

a step of providing a coil surrounding the coil

insulating powder;

a step of axially pressing at least the coil and the insulating powder into a heating insert;

a step of filling a part of an inner space of the glow tube, which is not occupied by the heating element, with filling material;

a step of inserting a terminal bolt into the glow tube and establishing an electrical connection between terminal bolt and coil, preferably by press-fitting, caulking, magnet forming, screwing, welding or soldering; and

a step of sealing the interior of the glow tube with a sealing element. In other words, in the method according to the invention, as a first step, the helix must be shaped in such a way that after being pressed together with the helix

Insulating powder is compressed to a previously designed shape with one or more spiral diameters of the turns and certain distances between the individual turns, a so-called spiral design. Here, a single-material or two-material coil with heating and control coil made of different materials can be used as a helix. In the step of axially pressing the filament and the insulating powder to the heating insert is accordingly the helix together with the electrically insulating

Insulating powder is pressed or compressed into a composite, wherein the heating insert is an axially pressed component, also referred to as axially compressed component. This is to be understood as meaning a component made up of different components which are connected to each other by a component pressed in the axial direction

executed pressing or compacting process by means of at least one

Pressing tool are connected so that the pressed component retains its final shape and how a brittle material can be handled. Such a pressing tool usually consists of at least one plunger, also called a punch, which is to be pressed

Components can act on a compressive force, either the glow tube itself or a counter-mold or a counter punch together with a mold holding the components to be pressed and thereby generates a back pressure. The plunger can have a smooth pressing surface. According to a preferred development of the method according to the invention, the step of providing at least the helix and an insulating powder surrounding it may further comprise a powder compact arranged in the interior of the helix, that is in the cavity or helix surrounding the helical helix, preferably the helix Insulating powder and the powder compact consist of different powder materials or wherein the insulating powder and the powder compact consist of the same powder material with different particle sizes. Under a

Powder compact is a powder pressed and possibly hardened

Component to understand that can then be handled as a powder composite in the form of a single component. This has at the present Invention the advantage that a powder compact can be inserted into the coil and then in the step of pressing together with the coil and the insulating powder can be pressed to the heating insert without the powder of the powder compact mixed with the insulating powder before pressing.

According to a preferred embodiment of the method according to the invention, the step of axially pressing at least the helix and the

Insulating powder performed to the heating element in the glow tube. The centering aid is removed from the glow tube before the step of axial pressing. More specifically, before being pressed, the helix and the insulating powder are inside the one-side closed glow tube and are then pressed into the glow tube and compressed into the heating element, the helix being electrically connected to the glow tube prior to pressing, preferably by welding or brazing. In this case, the axial pressing by a

Plunger take place, which has either a smooth pressure-exerting side or face or wherein the pressure-exerting side of the plunger preferably has a recess or notch in which a first end of the coil is received, namely the end of the coil forming the positive contact, the later brought into contact with the terminal bolt. However, the pressure-exerting end of the plunger may also have a tapered outer diameter, then in the step of axial pressing, the pressure-exerting end of the plunger is surrounded by the first end of the coil, so that in the step of the axial

Pressing no axial pressing pressure is exerted on the first end of the helix. This means that the first end of the helix has a helix diameter that allows the pressure-exerting end of the helix to be turned

Retains plunger within the windings of the first end of the helix. In this case, since the second end of the helix has a smaller helix diameter, only pressure is applied to the helix in a step of axial pressing

Portion of the coil having the smaller coil diameter, and the portion of the coil with a larger coil diameter undergoes no axial pressing force and remains in its preformed shape, while the other portion of the coil is pressed and compressed. According to an alternative preferred development of the method according to the invention, the step of axially pressing at least the helix and the insulating powder to the heating insert is carried out independently of the glow tube separately in a pressing device which consists of at least a plunger, a counterpressure punch and a die, preferably a cylindrical die , The steps of providing and centering at least the helix using the centering aid, providing the insulating powder surrounding the helix, and axially pressing at least the helix and surrounding insulating powder into the heating insert in the pressing device can be carried out. After these steps, the finished pressed heating insert is inserted into the glow tube and the coil is electrically connected to the glow tube, preferably by a cohesive bonding method such as welding or soldering. Then, the method of the present invention is provided with the step of filling a part of an inner space of the glow tube with filler, the step of inserting a terminal bolt into the glow tube and establishing electrical connection between terminal bolt and coil, and the step of sealing the inner space of the glow tube with a sealing member continued.

According to a further preferred embodiment of the method according to the invention, the pressure-exerting side of the plunger may have a recess or notch in which a first end of the coil is received, namely the end of the coil which forms the positive contact, which in connection with the terminal bolt in connection is brought. Additionally or alternatively, the pressure exerting side of the

Counterpressure plunger have a recess or notch in which the other end of the coil is received, namely the end of the coil, which is materially connected to an inner side of the glow tube at its closed, exposed from the housing end, preferably by welding or soldering.

When using a pressing device with plunger,

Counterpressure punch and die can be the helix prior to the step of axial pressing and during the filling of the insulating powder in the mold held centered in the die by a centering member so that the insulating powder is evenly distributed around the helix. More precisely, the helix is inserted centrally in the mold by means of the centering component acting as a centering aid. The centering component can be a

Centering sleeve or the like. Subsequently, the insulating powder is poured into the remaining cavity of the mold and shaking the whole, so that the insulating powder is evenly distributed. Thereafter, the centering member is removed and additional insulating powder is added until the coil is completely covered by the insulating powder, and then shaken once more, so that the entire insulating powder in the mold uniformly distributed before pressing. The centering aid is thus removed from the mold prior to the step of axial pressing. Finally, the contents of the mold with a plunger to the heating insert axially, ie in the direction of

Longitudinal axis of the mold pressed. The pressed-in coil compact powder composite is then removed from the mold and inserted into the glow tube and connected thereto, after which the connecting bolt is inserted into the housing and connected to the free first end of the coil. Preferably, prior to the step of pressing, the second end of the coil to be connected to the glow tube may be a removable material, a so-called placeholder, preferably made of plastic foam or a similar spongy material, such as polyamide,

Polyurethane, etc. as polymers or Ni alloys in the case of metals, to keep this end of the coil free from insulating powder during the axial pressing step. After pressing, the spacer is removed from the second end of the coil and this is connected to the glow tube, for example by welding or soldering. The contacting of the other, first end of the coil with the connecting bolt is done by caulking, magnetic forming, screwing, press-fitting, welding or a similar method.

Advantages of the invention

With the radiator according to the invention for a glow plug or with the manufacturing method according to the invention, the heat conduction of helix to the glow tube surface can be secured and it can on the Reduction of the finished composite glow tube by means of rotary swaging dispensed with or at least significantly reduced. Thus, the heat conduction is secured by helix or the Heizwendelabschnitt the coil to the glow tube, with a considerable saving of Komprimierschritten the finished composite glow tube is achieved by avoiding the swirling. The production of the radiator without swaging the coil is less damaged or left completely intact, which significantly improves both the reproducibility of the process and the robustness of the glow plug.

The present invention thus provides a radiator for a glow plug and a related manufacturing method that significantly reduces the undesirable deformation of the coil of the radiator during the rotary swaging of the glow tube or even completely avoids. This is done by an axial compression of coil and electrically insulating but thermally conductive insulating powder to a compressed heating element before or after its installation in the glow tube, wherein the heating insert is electrically conductive in the axial direction and electrically insulating in the radial direction.

Brief description of the drawings

Figure 1 shows a radiator for a glow plug according to a first

preferred embodiment of the invention in a cutaway cross-sectional view;

Figure 2 shows a radiator for a glow plug according to a second preferred embodiment of the invention in a cutaway cross-sectional view;

Figure 3 shows a radiator for a glow plug according to a third

preferred embodiment of the invention in a cutaway cross-sectional view; FIG. 4 shows successive steps of a manufacturing method of the radiator for a glow plug according to the first preferred embodiment shown in FIG. 1 in a cross-sectional view;

FIG. 5 shows an extract of successive steps of a

Production method of the radiator shown in Figure 2 for a glow plug according to the second preferred embodiment in a cross-sectional view;

FIG. 6 shows an extract of successive steps of a

Manufacturing process of the radiator shown in Figure 3 for a glow plug according to the third preferred embodiment in a cross-sectional view;

Figure 7 shows an extract of successive steps of an alternative

Production method of the radiator shown in Figure 2 for a glow plug according to the second preferred embodiment in a cross-sectional view; and

Figure 8 shows a glow plug according to the prior art in a

Cross-sectional view.

Embodiments of the invention

1 shows a radiator 1 according to the invention for a glow plug according to a first preferred embodiment, in which for reasons of clarity components such as a housing and

Insulating components and connecting elements have been omitted. The radiator 1 shown in Figure 1 has a metal glow tube 11, a heating insert 12 disposed therein, which is disposed inside a closed end 112 of the glow tube 11, and a connection bolt 13 which communicates via a contact element 14 with the heating element 12. The heating element 12 and the connecting bolt 13 are from the side of an open end 111 of the Inserted glow tube 11 in this, which is arranged opposite to the closed end 112 of the glow tube 11.

The heating insert 12 consists of a compressed composite of a coil 121 and an insulating powder 122. A first end 1211 of the coil 121, which is arranged opposite to the closed end 112 of the glow tube 11, establishes the connection of the heating insert 12 with the contact element 14. A second end 1212 of the coil 121 is in electrical connection with the closed end 112 of the glow tube 11, wherein the second end 1212 of the coil 121 with the closed end 112 of the glow tube 11 cohesively in

Connection is, for example, by the second end 1212 of the coil 121 is welded to the inside of the glow tube 11 at the closed end 112, or by the second end 1212 of the coil 121 is connected through the closed end 112 with this material fit.

The part of the connecting bolt 13, which is located within the glow tube 11, and the contact element 14, in the form of an electrically conductive and elastically deformable body such as in the form of a metal spring, a

Graphite tablet or the like are surrounded by an electrically insulating filling material 15, such as a ceramic powder, a sintered ceramic, a ceramic foam or the like, wherein the

Filler material 15 is held by an annular insulating sealing element 16 in the glow tube 11. The filling material 15 is filled through the open end 111 of the glow tube 11. Instead of the filling material 15 may alternatively also

Be provided empty space.

Similar to Figure 1, Figure 2 shows a radiator 1 'according to the invention for a glow plug according to a second preferred embodiment, in which for reasons of clarity components such as a housing and insulating components and connecting elements have been omitted.

The illustrated in Figure 2 part of the radiator 1 'according to the invention has a metal glow tube 11', a heating insert 12 'disposed therein, which is disposed inside a closed end 112' of the glow tube 11 ', and a connection bolt 13', which is connected to the heating element 12 'communicates. The heating element 12 'and the connecting bolt 13' are inserted from the side of an open end 111 'of the glow tube 11' in this, which is arranged opposite to the closed end 112 'of the glow tube 11'.

The heating insert 12 'consists of a compressed composite of a coil 121' and an insulating powder 122 '. A first end 1211 'of the coil 121' opposite to the closed end 112 'of the glow tube 11'

is arranged, the connection of the heating element 12 'with the

Connecting bolt 13 'forth. A second end 1211 'of the coil 121' in this case differs from the embodiment shown in FIG. 1 from a coil section projecting from the heating element 12 'in the direction of the connecting bolt 13', which protrudes into a recess 131 'of the connecting bolt 13' and with the latter Ground is materially connected, the

Recess 131 'in which the filament 121' facing the end of the

Connection bolt 13 'is provided. The second end 1212 'of the coil 121' is similar to the embodiment shown in FIG

closed end 112 'of the glow tube 11' in electrical connection, for example by the second end 1212 'of the coil 121' with the inside of the glow tube 11 'at its closed end 112' is welded, or by the second end 1212 'of the coil 121' through the closed end 112 'is continuously connected to this cohesively.

The part of the connecting bolt 13 ', which is located within the glow tube 11', as well as the projecting from the heating element 12 'end 1211' of the coil 121 'are surrounded by an electrically insulating filler 15', such as

Example, a ceramic powder, a sintered ceramic, a ceramic foam or the like, wherein the filling material 15 'is held by an annular insulating sealing member 16' in the glow tube 11 '. The filling material 15 'is filled through the open end 111' of the glow tube 11 '. Instead of

Filling material 15 'may alternatively be provided empty space.

Similar to Figures 1 and 2, Figure 3 shows a radiator according to the invention 1 "for a glow plug according to a third preferred embodiment, in which for reasons of clarity components such as a housing and insulating components and connecting elements have been omitted. The heating element 1 "according to the invention shown in FIG. 3 shows a metal glow tube 11", a heating insert 12 "arranged inside a closed end 112" of the glow tube 11 ", and a connection bolt 13" connected to the heating element 12 ". The heating insert 12 "and the connecting bolt 13" are inserted from the side of an open end 111 "of the glow tube 11", which is arranged opposite to the closed end 112 "of the glow tube 11" Third preferred embodiment, unlike the previously described embodiments has a varying diameter and consists of the open end 111 "of the glow tube

11 "towards the closed end 112" of the glow tube 11 "of a first portion IIA" of larger diameter and a second portion IIB "of smaller diameter, wherein a transition between the first

Section IIA "and the second section IIB" is gradually tapered. This results in the interior of the glow tube 11 "a funnel shape, which is closer to the closed end 112" of the glow tube 11 "out.

The heating insert 12 "consists of a compressed composite of a coil 121" and an insulating powder 122 ". A first end 1211" of the coil 121 "opposite to the closed end 112" of the glow tube 11 "constitutes the connection of the heating insert 12 "with the

The first end 1211 "of the coil 121", which communicates with the connecting bolt 13 ", in this case consists, unlike in the preceding embodiments, of a heating element protruding from the heating insert 12" in the direction of the connecting bolt 13 " has an extended shape with enlarged inner diameter, so one

Winding shape, in which the distance between the individual turns and their spiral diameter is greater than that in the insulating powder 122 "arranged part of the coil 121". The first end 1211 "of the coil 121 'is partially wrapped around the connecting bolt 13" and connected to this materially. A second end 1212 "helix 121" is in electrical communication with the closed end 112 "of the glow tube 11" similar to the previous embodiments, for example by the second end 1212 "of the helix 121" with the inside of the glow tube 11 "at the end thereof 111 "is welded, or by the second end 1212" the helix 121 " through the closed end 112 "is connected to this materially bonded.

The part of the connecting bolt 13 "located inside the glow tube 11" and the first end 1211 "of the coil 121" protruding from the heating element 12 "are surrounded by an electrically insulating filling material 15", such as a ceramic powder, a sintered ceramic a ceramic foam or the like, wherein the filling material 15 "is held in the glow tube 11" by an annular insulating sealing member 16 "." The filling material 15 "protrudes with a portion 151" into one in the heating insert

12 "pressed in cavities 1221", more precisely in a in the insulating powder 122 "pressed in cavities 1221" inside. The resulting overlap of Isolierpulver 122 "and filling material 15", ie the part 151 "of the filling material 15 ', which is in the voids 1221" is within the funnel generated by the glow tube 11 "funnel, ie in the region of the transition from the first section IIA "in the second section IIB" of the glow tube 11 ". Instead of the filling material 15 "may also be provided empty space.

FIG. 4 shows a sequence of individual steps (a) to (f) involving a

Manufacturing method of the one shown in Figure 1 and described above

Radiator 1 represent. In the first step (a), the preformed helix 121 is first inserted into the glow tube 11 and connected at its second end 1212 to the closed end 112 of the glow tube 11, for example by the second end 1212 of the helix 121 with the inside of the glow tube 11 welded at its closed end 112. The first end 1211 of the helix 121 is held centrally by a centering aid 2 in the glow tube 11, which is inserted into the glow tube 11. In the subsequent step (b), the insulating powder 122 is filled in the glow tube 11, while the first end 1211 of the coil 121 is further held by a centering aid 2 in the center of the glow tube 11, so that the

Insulating powder 122 evenly distributed around the coil 121 around and this completely covered. Subsequently, in a step (c) the centering aid 2 is removed from the glow tube 11 and a plunger 3 is inserted into the glow tube 11, which comes into contact with the composite of coil 121 and insulating powder 122. The coil 121 still has its preformed shape in this state Output length LI on. By the plunger 3 and the glow tube 11, a force F is exerted on both sides of the helix insulating powder composite. The glow tube 11 is preferably held in a (not shown) holder or the like in order to provide a counter force against the force exerted by the plunger 3 force. By the exercise of

Compressive force F from both sides of the helix insulating powder composite is compressed from step (c) to step (d) of the spiral insulating powder composite and to the desired heating insert 12 in the form of a composite of helix 121 and compacted or compressed insulating powder 122, So pressed into a spiral compact powder composite. This process of compacting the

Composite of helix 121 and insulating powder 122 to the heating element 12 in the form of helical Kompaktpulver- composite is referred to as the step of axial pressing. In this case, the coil 121 after compression by the plunger 3 has a reduced overall length L2, which is smaller than the

Initial length LI is. The plunger 3 is then removed from the glow tube 11 leaving the newly manufactured heater insert 12 in the glow tube 11, see step (e). Subsequently, the contact element 14 and the

Connection bolt 13 inserted into the glow tube 11, wherein the contact element 14 makes electrical contact between the first end 1211 of the coil 121 and the connecting bolt 13. Furthermore, the remaining space in the

Glow tube 11 filled with the filler 15 in the form of a ceramic powder, which completely surrounds the contact element 14 and arranged in the glow tube 11 of the connecting bolt 13. The interior of the glow tube 11 is further sealed by the sealing element 16.

FIG. 5 shows a modified form of the step sequence shown in FIG. 4, in which steps (c), (d) and (f) are to be replaced by steps (c '), (d') and (f), and FIGS thus constitute a manufacturing method of the radiator 1 'shown in FIG. 2 and described above. The remaining steps are identical to the respective steps of the method illustrated in FIG. A significant difference in the method shown in Figure 5 can be found in the nature of the plunger 3 'and the first end 1211' of the coil 121 '. As can be seen in step (c '), the plunger 3' on its pressure-exerting side or end face has a recess 31 'in which the first end 1211' of the coil 121 'is received in the axial pressing becomes. This makes it possible that the coil 121 'by the plunger 3' with the insulating powder 122 'compressed and thereby the initial length LI is reduced to the reduced overall length L2. The moreover protruding helical portion in the form of the first end 1211 'of the helix 121' is thereby not compressed in the step of axial pressing and remains in its

Original shape. After removal of the plunger 3 'from the glow tube 11', the heating insert 12 'produced by the axial pressing remains in the glow tube 11'. Subsequently, the connecting bolt 13 'is inserted into the glow tube 11' and an electrical contact between the first end 1211 'of the coil 121' and the connecting bolt 13 'produced. The protruding first end 1211 'of the coil 121' is in a recess 131 '

received, which is provided in the terminal bolt 13 'in its end face, which faces the closed end 112' of the glow tube 11 '. Furthermore, the remaining space in the glow tube 11 'filled with the filler 15' in the form of a ceramic powder, which arranged in the glow tube 11 'part of the

Connecting bolt 13 'and the protruding first end 1211' of the coil 121 'completely surrounds. The interior of the glow tube 11 'is further sealed by the sealing element 16'. FIG. 6 shows a further modified form of that shown in FIG

Step sequence in which steps (c), (d) and (f) are to be replaced by the steps (c "), (d") and (f ") and thus a manufacturing method of the shown in Figure 3 and above described radiator 1 "represent. The remaining steps are identical to the respective steps of the method illustrated in FIG. In the further modified in the shown in Figure 6

Form the heating element 12 "before pressing also in the form of the coil 121" and the insulating powder 122 "loosely in the glow tube 11", wherein the second end 1212 "the coil 121" already with the closed end 112 "of the glow tube 11" cohesively in electrical connection. At step (c "), a plunger 3" is again inserted into the glow tube 11 ', with the first end 1211 "of the coil 121" being so large

Spiral diameter has that, although it is held by a centering 2 "in the center of the glow tube 11", the plunger 3 "but through the spiral turns within it is arranged and with its pressure-exerting end face on the Isolierpulver 122" rests. The plunger 3 "indicates its pressure-exerting end to a tapered outer diameter, which thereby has a conical shape. The initial length LI of the rest of the coil 121 "is located inside the insulating powder 122", so it is completely surrounded by this. By means of the force application with the force F by the plunger 3 "that is the rest of the coil 121" surrounding

Insulating powder 122 "compressed and thus reduces its overall length to L2, the coil 121" correspondingly compressed. Due to the conical shape of the pressure-exerting end of the plunger 3 "is a corresponding

Counter-mold in the insulating powder 122 "pressed so that it spreads upward around the plunger 3" around, so that the resulting voids 1221 "is pressed into the insulating powder 122", see step (d ").

The centering aid 2 "remains in the glow tube 11" during the axial pressing step to keep the first end 1211 "of the coil 121" centered and thereby center the plunger 3 "

Insulation powder 122 "thus extends over the second portion IIB" of smaller diameter of the glow tube 11 "and over the transition between the first portion IIA" and the second portion IIB ", which gradually tapers, see Figure 3. The first end 1211" As a result, the coil 121 "experiences no axial pressing force and retains its original shape. After removal of the plunger 3" from the glow tube 11 ", the heating insert 12" produced by the axial pressing remains in the glow tube 11 ".

Subsequently, the terminal bolt 13 "is inserted into the glow tube 11" and protrudes at least partially into the first end 1211 "of the coil 121", with the terminal bolt 13 'coming into contact therewith, whereby an electrical contact between the first end 1211 "of the Furthermore, the remaining space in the glow tube 11 "including the voids 1221" is filled up with the filling material 15 "in the form of a ceramic powder which surrounds the part of the connecting bolt 13" arranged in the glow tube 11 ". and the protruding first end 1211 "completely surrounds the coil 121". The filling material 15 "protrudes with a portion 151" into the cavity 12 "pressed in the heating insert 12", more precisely into the cavities 1221 "pressed into the insulating powder 122. The interior of the glow tube 11 "is further sealed by the sealing element 16". FIG. 7 shows an alternative method with the steps (B), (C), (D), (E) and (F), in which a heating body 1 'is produced, as already known from FIG. In this case, a pressing device 4 'is used, which consists of a pressure punch 41', a counter punch 42 'and a die 43'. The mold 43 'may have a one-piece shape, but may also have a two- or multi-part shape. The first end 1211 'of the coil 121' is held by a centering aid 2 'in the center in the mold 43', more precisely in a through hole 431 'of the mold 43', as can be seen in step (B). Further, the second end 1212 'of the coil 121' in a

Recess 421 'is included, which is provided in the pressure-exerting end face of the counterpressure plunger 42'. The insulating powder 122 'is in the

Press mold 43 'filled while the first end 1211' of the coil 121 'is further held by the centering aid 2' in the middle in the mold 43 ', so that the insulating powder 122' evenly distributed around the coil 121 'around and covered as completely as possible , Subsequently, in a step (C), the centering aid 2 'is removed from the die 43' and the pressure punch 41 'inserted into the die 43', so that the coil 121 'together with the

Insulating powder 122 'between the plunger 41' and the counter-pressure piston 42 'in the through hole 431' of the die 43 'is held.

The first end 1211 'of the coil 121' is received in a recess 411 'of the plunger 41'. Subsequently, a pressure force F on the plunger 41 'and a pressing force F on the

Counter punch 42 'applied and the coil 121' together with the

Isolierpulver 122 'to the heating element 12' axially pressed, so that the

Total length of coil 121 'is compressed from LI to L2, see step (D). The first end 1211 'and the second end 1212' of the coil 121 'are not further compressed by their placement in the recesses 411' and 421 '. The first end 1211 'and the second end 1212' of the coil 121 'may each be surrounded by a removable plastic foam to keep them free of insulating powder 122' during the axial pressing step. In step (E), the heating element 12 'can be removed from the pressing device 4' and the plastic foam can be removed so that the two ends 121 1 'and 1212' of the coil 121 'are free of insulating powder 122' the heating insert 12 'protrude. Subsequently, the heating insert 12 'is inserted into the glow tube 11' in step (F) and the second end 1212 'of the coil 121' is integrally connected to the closed end 112 'of the glow tube 11' so that they are in electrical connection with one another.

Subsequently, the connection bolt 13 'is inserted into the glow tube 11' and establishes an electrical contact between the first end 1211 'of the coil 121' and the connection bolt 13 '.

The protruding first end 1211 'of the coil 121' is in the

Recess 131 'is included, which is provided in the terminal bolt 13' in its end face, which to the closed end 112 'of

Glow tube 11 'has. Furthermore, the remaining space is filled in the glow tube 11 'with the filler 15' in the form of a ceramic powder, which in the glow tube 11 'arranged part of the connecting bolt 13' and the

projecting first end 1211 'of the coil 121' completely surrounds. The interior of the glow tube 11 'is further sealed by the sealing element 16'.

The technical features of the embodiments described above, both the radiator of the glow plug and its

Manufacturing process are not described on the respective

Embodiment limited and are correspondingly interchangeable.

Claims

claims

1. Radiator (1, 1 ', 1 ") for an electrically heatable glow plug, with a glow tube (11, 1, 11"), and

a heating insert (12; 12 '; 12 ") arranged in the glow tube (11; 11'; 11"), the at least one coil (121; 12; 121 ") and an insulating powder (122; 122 '; 122") pressed therewith; ) having,

wherein the heating element (12; 12 ', 12 ") is an axially pressed component.

2. Radiator (1, 1 ', 1' ') according to claim 1, wherein the heating insert (12, 12';

12 ") further comprises a powder compact arranged in an internal cavity of the coil (121; 121 '; 121"), preferably wherein the insulating powder (122; 122'; 122 ") and the powder compact are made

or wherein the insulating powder (122, 122 ', 122 ") and the powder compact are made of the same powder material having different grain sizes.

3. Radiator (1, 1 ', 1' ') according to claim 1 or 2, wherein the coil (121;

121 '; 121 ") of the heating insert (12; 12 '; 12") is electrically connected to the glow tube (11; 11'; 11 "), preferably by welding or soldering.

4. Electrically heatable glow plug with a radiator (1, 1 ', 1 ") according to one of the preceding claims, which preferably further comprises a housing for receiving the radiator (1, 1', 1"), at least one electrically insulating housing seal for isolating between a terminal bolt (13, 13 ', 13 ") and the housing, a circular connector and an insulating disc, which is provided for electrical insulation between the circular connector and the housing. Method for producing a radiator (1; 1 ', 1 ") for an electrically heatable glow plug, in particular a radiator (1; 1';1") according to one of Claims 1 to 3, comprising the following steps:

Forming at least part of a coil (121; 121 '; 121 ") such that it has a predetermined shape after a subsequent step of axially pressing;

Providing and centering at least the helix (121; 121 '; 121 ") using a centering aid (2; 2");

Providing an insulating powder (122; 122 '; 122 ") surrounding the coil (121; 121'; 121");

Axially pressing at least the coil (121, 121 ', 121 ") and the surrounding insulating powder (122, 122', 122") into a heating insert

(12; 12 '; 12 ");

Filling a part of an inner space of the glow tube (11; 11 '; 11 ") which is not occupied by the heating insert (12; 12'; 12") with filling material (15; 15 '; 15 ");

Inserting a connecting bolt (13; 13 '; 13 ") into the glow tube (11; 11'; 11") and establishing an electrical connection between connecting bolts (13; 13 '; 13 ") and helix (121; 121'; 121"). ); and

Sealing the interior of the glow tube (11; 11 '; 11 ") with a sealing element (16; 16'; 16").

The method of claim 4, wherein the step of axially compressing at least the coil (121; 121 '; 121 ") and the insulating powder (122; 122'; 122") to the heating insert (12; 12 '; 12 ") in the glow tube (11; 11 '; 11 "), wherein the coil (121; 121'; 121") is electrically connected to the glow tube (11) prior to the step of axial pressing, preferably by welding or brazing.

Method according to claim 5, wherein the axial pressing takes place in the glow tube (11; 11 '; 11 ") by a pressure ram (3; 3'; 3"), preferably wherein

the pressure-exerting side of the plunger (3 ') a

Recess (31 ') in which a first end (1211') of the coil (121 ') is received, or the pressure-exerting end of the plunger (3 ") has a tapered outside diameter and in the step of axial pressing is surrounded by a first end (1211") of the coil (121 ") such that the first end (1211") of the coil (121 ") in the step of axial pressing no axial pressing pressure is applied.

The method of claim 5, wherein the step of axially pressing at least the coil (121 ') and the insulating powder (122') to the heating element (12 ') is performed in a pressing device (4') comprising at least one plunger (41 '). ), a counter punch (42 ') and a die (43').

The method of claim 8, wherein the steps of providing and centering at least the coil (121 ') using the centering aid (2), providing the insulating powder (122') surrounding the coil (121 '), and axially compressing at least the coil (121 ') and the surrounding insulating powder (122') to the

Heating insert (12 ') in the pressing device (4') is performed.

The method of claim 8 or 9, wherein the pressure-exerting side of the plunger (41 ') has a recess (411') in which a first end (1211 ') of the coil (121') is received, and / or wherein the pressure-exerting side the counterpressure punch (42 ') has a recess (421') in which the second end (1212 ') of the coil (121') is received.

Method according to one of claims 8 to 10, wherein at least the second end (1212 ') of the helix (121') is surrounded with a removable material, preferably plastic foam, in order to keep it free of insulating powder (122 ') during the axial pressing step. to keep.

Method according to one of claims 5 to 11, wherein the centering aid (2) is removed prior to the step of axial pressing.