JP2017527769A - Glow pin plug - Google Patents

Abstract

An electrically heated glow pin plug for cold start assistance of an auto-ignition internal combustion engine such as a diesel engine is proposed.
A housing (2), a protective tube (3) coupled to the housing (2), a positive electrode (41) and a negative electrode (42) are provided, and are held inside the protective tube (3). A ceramic heating element (4) and a conductive connecting bolt (41) electrically connected to the positive electrode (41) of the ceramic heating element (4) via a conductive contact element (6) 5) an electrically heated glow pin plug (1) comprising a conductive contact element (6) which is compressible, a connecting bolt (5) and a positive pole of a ceramic heating element (4) ( 41), and at least the positive electrode (41) of the ceramic heating element (4), and if necessary, the contact element (6) is also located outside the housing (2). It is provided inside the protective tube (3).
[Selection] Figure 1

Description

  The present invention relates to a glow plug or glow pin plug, more precisely to a ceramic glow pin plug for installation in a chamber of an internal combustion engine, for example in the front chamber, vortex chamber or combustion chamber of an air compression / auto ignition diesel engine. .

  In modern automobiles and other applications, diesel engines with higher efficiency are widely used compared to gasoline-driven internal combustion engines. However, in many cases, diesel engines require cold start assistance during the start-up step, since the cold start of the diesel engine usually does not allow smooth auto ignition of the injected diesel fuel. Even after starting, a glow pin plug may be used to improve the cold operation of the engine and its displacement. Furthermore, different fuel qualities can reduce the combustibility of the compressed air / diesel mixture.

  To accommodate the above effects, inside the combustion space of a diesel engine, it is used to pre-glow the diesel engine at the start stage, also called GLP (derived from the English term “glow plug”), usually At least one electrically heated glow pin plug is located in each case. Glow pin plugs may also include metal or ceramic heating elements, also called glow pins. Further, the above glow pin plug is used in a wide range as a cold start aid at the start of a gas turbine driven by kerosene and oil heating. In known glow pin plugs with ceramic glow pins, the glow pins are usually made of an electrically insulated ceramic material into which a highly conductive power line and an internal heat conductor may be embedded. .

  A ceramic glow pin, also called a ceramic pin, is fixed in a protective tube and is hermetically pressed into the glow pin plug housing. The electrical contact of the positive pole of the ceramic pin, usually provided by a thermal conductor contact provided at the end of the ceramic pin, is made by a connecting bolt that is coupled to the positive pole of the ceramic ceramic pin via a wire. The electrical contact of the negative electrode of the ceramic pin, that is, the ground connection with the engine block, is formed through the protective tube of the ceramic pin and the housing. In the known glow pin plug, wiring connection between the connection bolt and the positive pole of the ceramic pin is usually performed by brazing. As an alternative, the connection between the connecting bolt and the positive pole may also be made by a crimped or brazed metal sleeve. However, the connection using brazed wires or inserted metal sleeves requires a certain amount of stability, which is usually done by inserting powder into a protective tube and then compression molding, which is a laborious production. Leads to a process.

  For the purpose of simplifying the contact between the connecting bolt and the positive electrode, for example, as shown in the schematic cross-sectional view of FIG. 3, the same contact in the glow pin plug 9 is surrounded by a compressible element. Are known. Here, the glow pin plug 9 comprises in principle a connection bolt 91, a heating element in the form of a ceramic pin 92, a rigid metal housing 93 and a plastic sleeve 94. Here, the plus contact of the ceramic pin 92 is performed by the connecting bolt 91 via the graphite pellet 95 used as a contact element having elasticity, and the plus contact of the ceramic pin 92, the graphite pellet 95 and the graphite pellet are in contact with each other. The end of the connecting bolt 91 is disposed inside the housing 93 having the rigidity of the glow pin plug 9, that is, inside the hollow of the housing 93 of the glow pin plug 9. Here, the ceramic pin 92 is typically made of a material that is more brittle than the metal housing 93, and as a result, acts on the ceramic pin 92 from the side, for example, exceeding the rigidity of the ceramic pin, under conditions of excessive loading on the ceramic pin 92. The action of force can usually lead to breakage of the ceramic pin 92.

  In particular, the known wiring contact in the glow pin plug described above requires, as a result, a time-consuming manufacturing method that requires brazing to be performed more frequently, so that the assembly of the glow pin plug becomes difficult. Expensive. Further, in the known modification of the contact of the glow pin plug using the graphite pellet 95, as can be read from Patent Document 1 described above, the ceramic is passed through the graphite pellet 95 by the connecting bolt 91 inside the housing 93 having rigidity. A highly rigid structure of the glow pin plug 9 provided with the contact of the pin 92 is obtained. When the glow pin plug 9 is attached to the cylinder head of the internal combustion engine, due to the structure having the above rigidity, for example, the end portion of the ceramic pin 92 in an open position is suspended on the other edge portion of the cylinder head. When installed, a bending force is applied to the ceramic pin 92 by inadvertent operation, and the ceramic pin 92 does not bend, but rather easily breaks in the metal housing 93 due to its brittleness and rigidity. It may result in falling into the combustion space. Thus, the necessary removal and re-installation of the cylinder head due to the removal of the broken part of the ceramic pin 92 from the cylinder head results in a significant delay in the installation time, and also inconvenient additional costs associated with this. Bring.

German Patent Application No. 10339641

  According to the invention, an electrically heated glow pin plug with the technical features of claim 1 is preferably proposed for cold start assistance of an auto-ignition internal combustion engine, for example a diesel engine. Advantageous modifications of the invention are characterized by the technical features of the dependent claims.

  Accordingly, the present invention provides a housing, also referred to as a plug housing, a protective tube coupled to the housing, a ceramic heating element held within the protective tube, comprising a positive electrode and a negative electrode, And an electrically heated glow pin plug according to the present invention comprising a conductive connecting bolt electrically connected to the positive pole of the heating element via the contact element. The protective tube is usually a tubular part that can be formed as an independent part or sometimes as a part of the housing of the glow pin plug. Furthermore, the conductive contact element is compressible and elastic and is arranged between the connecting bolt and the positive pole of the ceramic heating element, at least the positive pole of the ceramic heating element is external to the housing in the protective tube. It arrange | positions so that it may be located in. In the solution according to the invention, as a result, the contact of the positive pole from the housing area is shifted into a part of the protective tube outside the housing. Preferably, the conductive contact element is also arranged to be located outside the housing in the protective tube.

  The ceramic heating element of the glow pin plug of the present invention is also referred to as a glow pin or ceramic pin, where, as is known from the prior art discussed above, in principle there is a highly conductive power line therein. It is made of an electrically insulated ceramic material, such as silicon nitride, which can be embedded with a heat conductor disposed on the inside, and the heating function and the control function are used together in the heat conductor. The positive pole is formed by the end of the heat conductor exposed at the end held by the rest of the glow pin plug of the ceramic heating element, the negative pole is preferably a glow pin plug formed from metal The outer shell of the heating element coupled to the engine block as a ground connection and the heat conductor are connected via the protective tube and the housing. The ceramic heating element is used for contact of the heat conductor, as is already known from the prior art, with the end projecting towards the inside of the combustion space of the internal combustion engine, usually as a positive pole in the heating element And an end portion forming a positive pole surface. That is, in the glow pin plug of the present invention, the positive electrode of the ceramic heating element located at the end provided inside the protective tube of the ceramic heating element and the conductive contact element in direct contact therewith are both The glow pin plug is disposed inside the protective tube so as to be positioned outside the housing in the longitudinal direction (axial direction). According to the modified form of the glow pin plug of the present invention, the end connected to the conductive contact element of the conductive connecting bolt may be disposed inside the housing. As an alternative to this, this end may be arranged inside the protective tube so as to be outside the housing, as well as the positive pole and the conductive contact element of the ceramic heating element.

  More precisely, when assembling the glow pin plug of the present invention, it is certain that a part of the protective tube is arranged inside the housing, that is, inside the hollow space where at least one of the inside of the glow pin plug housing is open. However, at least the positive pole of the heating element made of ceramic, and the conductive contact element connected to the ceramic heating element are not arranged inside the hollow space of the housing. And therefore located outside the housing of the glow pin plug. As an alternative to this, the protective tube may be fixed on the housing so that no part of the protective tube is arranged inside the housing, but instead the protective tube may form a kind of extension of the housing.

  Due to the positive position of the ceramic heating element outside the housing inside the protective tube and, if necessary, the special arrangement of conductive contact elements, the “short” ceramic heating element is inside the protective tube but outside the housing. Held in this way under the condition of excessive loading of the ceramic heating element by the action of forces from the side to the ceramic heating element, without breaking the ceramic heating element, here the ceramic heating A so-called “flexible design” of the glow pin plug is created, in which a protective tube having a strength significantly lower than that of the element makes it possible to counteract the action of force by plastic deformation. Since the conductive contact element remains flexible after compression or decompression, the flexible contact between the connecting bolt and the positive pole of the ceramic heating element is a compressible contact element. Created using In this way, the orientation of the ceramic heating element, usually coaxial with the connection bolt, is allowed to vary, i.e. the angle at which the longitudinal axis of the ceramic heating element is greater than 180 ° relative to the longitudinal axis of the connection bolt It is allowed that the contact between the positive pole of the ceramic heating element and the connecting bolt is not interrupted. As a result, electrical contact of the ceramic heating element by the connecting bolt and further heating of the ceramic heating element after bending the protective tube together with the ceramic heating element are possible. Here, the end portion disposed inside the protective tube of the ceramic heating element including the positive electrode may have a truncated cone shape. As an alternative to this, the above-mentioned rear end of the ceramic heating element, in which the positive pole contact surface is located, comprises a front face at an angle of 90 ° with the longitudinal axis of the ceramic heating element, or A cylindrical protrusion may be arranged on the front surface as a protruding positive electrode contact surface.

  According to another preferred variant of the glow pin plug according to the invention, at least the positive pole of the heating element made of ceramic and the part located outside the protective tube housing in which the conductive contact element is arranged are protected. It may have a lower resistance torque than the portion located inside the housing of the tube. The above may be realized by a wall thickness that is equal to or less than that of the portion of the protective tube located outside the housing compared to the portion of the protective tube located inside the housing. Here, the portion located inside the housing of the protective tube preferably has a wall thickness of 0.88 to 1.4 mm, more preferably 0.93 mm, where the portion located outside the housing of the protective tube is The wall thickness is preferably 0.5 to 0.8 mm, more preferably 0.55 mm. Further, the protective tube of the glow pin plug of the present invention may be made of a ductile material, preferably a ferritic or martensitic corrosion resistant steel. Here, the strength of the protective tube does not exceed the strength of the ceramic heating element even if the protective tube is deformed under the condition of bending load acting on the ceramic heating element. The electrical connection between the positive electrode and the connecting bolt is selected to be maintained by the conductive contact element. In order to ensure the above, it is preferred that the conductive contact element is coupled to the positive electrode without utilizing the properties of the material. Here, the conductive contact element may be coupled to the positive pole, preferably by an interference fit, and more preferably, the conductive contact element is connected to the positive pole of the ceramic heating element and the ceramic inside the housing. It may be coupled by being fitted between the corresponding ends of the connecting bolts oriented and positioned towards the heating element made of metal. The conductive contact element may be pre-loaded by connecting bolts accordingly. Furthermore, preloading of the conductive contact elements or connecting bolts is maintained by appropriate measures in the area of the protective tube or housing, but a variety of solutions are possible.

  The glow pin plug of the present invention may further include a cover part. The cover component may be a sealing that holds the ceramic powder inside the protective tube and closes the hollow space of the housing in order to prevent dust and moisture from entering. In addition or as an alternative, the cover part may also be implemented in the form of an electrically insulated sheath that further electrically insulates and mechanically supports the connecting bolt relative to the housing. .

  The conductive contact element of the glow pin plug of the present invention has conductive properties. According to a preferred variant of the glow pin plug according to the invention, the conductive contact elements are all in solid form, for example conductive powders such as metal powder, in particular silver powder, graphite powder or conductive ceramic powder. It may be made of a powder or a porous sintered body preferably made of the same material. As an alternative or in addition to this, the conductive contact element may have a pellet shape. Furthermore, the conductive contact element may consist of a rolled and / or press-formed metal web, which is preferably metal wool and the metal is not oxidized. Examples of the above metals are copper, bronze, brass, steel, stainless steel, silver or nickel. Metal webs that are more oxidizable but coated with a coating such as silver or nickel are also used. As an alternative or in addition to this, the electrically conductive contact element may preferably consist of a graphite-based elastic material. Here, graphite is preferably used as the material of the conductive contact element. However, alternatively or additionally, other suitable conductive materials can be used.

  According to another preferred variant of the glow pin plug according to the invention, preferably between the connecting bolt inside the protective tube and the protective tube, preferably the positive pole of the connecting bolt, the conductive contact element and the ceramic heating element An insulating sheath that electrically insulates the protective tube from the protective tube may be provided. Here, the insulating sheath is preferably made of a plastic such as polyimide (PI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), or from a fluoroelastomer, silicon elastomer or glass wool having high temperature resistance. Become.

  The glow pin plug implemented in accordance with the present invention, compared to the prior art described above, for the use of a flexible, conductive contact element, for the contact between the connecting bolt and the ceramic heating element of the glow pin plug No electric wires are used, which has the advantage that the brazing of the electric wires between the parts mentioned above is unnecessary and thus the whole manufacturing process is cheaper. Furthermore, in the known glow pin plug, as explained above, in the situation of the action of an external mechanical force, a ceramic heating element usually joined by brazing or other means and its negative contact area or Disassembly or breakage between the positive contact area may occur. By using a compressible, flexible and conductive contact element that is bonded to the positive pole face of the ceramic heating element without exploiting the properties of the material, the ceramic heating element and the negative or positive contact area The effect of a direct force on the contact surface between the two can be prevented or at least mitigated, so that contact loss due to delamination between the aforementioned regions of the ceramic heating element does not occur. In addition, the solution of the present invention with the contact disposed outside the positive pole housing of the ceramic heating element breaks down the ceramic heating element due to bending forces that may act on itself. Can be mitigated or completely avoided. According to the present invention, the above contact of the positive electrode of the ceramic heating element with the flexible contact element is associated with the above “flexible design” for a new overall solution.

  Other advantages and preferred embodiments of the present invention will be apparent from the following description of the drawings.

1 is a schematic cross-sectional view of a glow pin plug according to a preferred embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a front portion of the glow pin plug of FIG. 1 according to an enlarged view. 1 is a schematic cross-sectional view of a glow pin plug with a flexible contact element according to the prior art. FIG.

  FIG. 1 is a schematic sectional view of a glow pin plug 1 according to a preferred embodiment of the present invention, and FIG. 2 is a schematic sectional view of a front portion of the glow pin plug 1 according to the present invention shown in FIG. .

  The glow pin plug 1 of the present invention is a ceramic heating element or housing comprising a housing 2, a protective tube 3 coupled to the housing 2, a positive electrode 41 also called a positive contact region and a negative electrode 42 also called a negative contact region 42. It consists of a glow pin 4, a conductive connecting bolt 5 and a conductive contact element 6 in the form of a graphite pellet. The ceramic heating element 4 having the positive electrode 41 and the negative electrode 42, the contact element 6, and the end 51 of the connecting bolt 5 that is electrically connected to the contact element 6 are as follows: In order to avoid a short circuit between 41 and the negative electrode 42, the contact element 6 and the end 51 of the connecting bolt 5 are disposed inside the insulating sheath 7 that electrically insulates the protective tube 3. The other end 52 of the connecting bolt 5 arranged in a direction away from the ceramic heating element 4, that is, more precisely the contact area 53 for electrical contact of the connecting bolt 5, In addition, a round plug 81 that is in electrical contact with the contact area 53 is inserted, as is known from prior art glow pin plugs. Further, an insulating disk 82 and a seal 83 made of a non-conductive material, preferably plastic, are disposed between the round plug 81 and the housing 2 or the connecting bolt 5.

  In a preferred embodiment, the protective tube 3 has a cylindrical shape that has a tapered structure toward the combustion space where the wall thickness decreases toward the combustion space. A part of the protective tube 3 with a thicker wall thickness is now press-fitted inside the housing 2 and is selectively welded to it in order to achieve a secure connection between the housing 2 and the protective tube 3 Or brazed. As an alternative to this, the protective tube 3 may be welded inside the housing 2. In the transition region between the housing 2 and the protective tube 3, in FIG. 2, a dotted line indicating the transition between these components is provided. In the preferred embodiment as shown in FIGS. 1 and 2, the inside of the protective tube 3 is clamped and fixed between the positive electrode 41 of the ceramic heating element 4 and the end 51 of the connecting bolt 5. The contact element 6 arranged in a state is located outside the housing 2 in terms of the overall construction, ie below the dotted line in FIG. 2, and therefore in the part of the protective tube 3, 0.88 to 1.4 mm, more To be precise, compared to the portion of the protective tube 3 having a wall thickness of 0.93 mm located inside the housing 2, the tapered diameter and 0.5 to 0.8 mm, more precisely 0.55 mm. It has a thin wall thickness.

  In order to maintain as much continuous contact as possible between the positive pole 41 and the connecting bolt 5, more precisely, the positive pole 41 and the end 51 of the connecting bolt 5, the contact element 6 is under pressure. There must be, and in a preferred embodiment the contact element 6 is elastic for the purposes described above. In attaching the glow pin plug 1 of the present invention, since the connection bolt 5 is press-fitted into the protective tube 3, the contact element 6 is preloaded. 1 and 2 can be caused by such an arrangement of the contact element 6 outside the housing 2 in the protective tube 3, for example by inadvertent installation of the glow pin plug 1 in a diesel engine. The compressive force acting on the ceramic heating element 4 or the protective tube 3 can be stopped by plastic deformation without breaking or wearing the protective tube 3. For this purpose, the protective tube 3 is a ductile material whose strength and geometric structure is adjusted so as to exceed its yield strength only under the condition of a lateral load on the heating element 4, but not to exceed the bending strength of the ceramic material. Therefore, it consists of a material such as a ferritic or martensitic corrosion resistant steel. In this way, the protective tube 3 is bent to receive the bending force acting from the outside, and the contact element 6 which can also be elastic for this purpose follows the position change caused by the bending and the shape change caused by the bending. And maintaining the electrical contact between the end 51 of the connecting bolt 5 can be realized. In this way, an electrical connection in the glow pin plug 1 can be ensured even under bending conditions due to improper use.

  As an example of the field of use of the glow pin plug configured as described above, and another field of use of the protective tube arrangement described above, as an example, to a fuel heater such as an ethanol heater in a flex start device or the like The use of can also be conceived.

DESCRIPTION OF SYMBOLS 1 Glow pin plug 2 Housing 3 Protection tube 4 Heating element 5 Connection bolt 6 Contact element 7 Insulation sheath 9 Glow pin plug 41 Positive pole 42 Negative pole 51 End part 52 End part 53 Contact area 81 Round plug 82 Insulating disk 83 Seal 91 Connection bolt 92 Ceramic pin 93 Housing 95 Graphite pellet

Claims (12)

  A housing (2), a protective tube (3) coupled to the housing (2), a positive electrode (41) and a negative electrode (42), and made of ceramic held inside the protective tube (3) Heating element (4) and a conductive connection bolt (5) electrically connected to the positive electrode (41) of the ceramic heating element (4) via a conductive contact element (6) The conductive contact element (6) is compressible and is arranged between the connecting bolt (5) and the positive pole (41) of the ceramic heating element (4). In the electrically heated glow pin plug (1), at least the positive electrode (41) of the ceramic heating element (4) is disposed outside the housing (2) in the protective tube (3). Glow pin plug characterized by that.   The positive electrode (41) and the contact element (6) of the ceramic heating element (4) are arranged outside the housing (2) in the protective tube (3). A glow pin plug (1) according to claim 1.   The end (51) connected to the conductive contact element (6) of the conductive connection bolt (5) is arranged inside the housing (2). Glow pin plug (1).   At least the positive electrode (41) of the ceramic heating element (4) and the conductive contact element (6) are located outside the housing (2) of the protective tube (3) disposed therein. Glow pin plug (1) according to any one of the preceding claims, wherein the part has a lower resistance torque than the part of the protective tube (3) located inside the housing (2).   Glow pin plug (1) according to any one of the preceding claims, wherein the protective tube (3) is made of a ductile material, preferably a ferritic or martensitic corrosion resistant steel.   The conductive contact element (6) is coupled to the positive electrode (41) of the ceramic heating element (4) without utilizing the properties of the material, and the conductive contact element (6) Glow pin plug (1) according to any one of the preceding claims, which is connected to the positive pole (41) of the ceramic heating element (4), preferably by an interference fit.   Glow pin plug (1) according to any one of the preceding claims, wherein the conductive contact element (6) consists of a conductive powder or a porous sintered body.   Glow pin plug (1) according to any one of the preceding claims, wherein the conductive contact element (6) has a pellet shape.   Glow pin plug (1) according to any one of the preceding claims, wherein the conductive contact element (6) consists of a rolled and / or pressed metal web, which is preferably metal wool. .   Glow pin plug (1) according to any one of the preceding claims, wherein the conductive contact element (6) is preferably made of a graphite-based elastic material.   Glow pin plug (1) according to any one of the preceding claims, wherein the conductive contact element (6) is preloaded by the connecting bolt (5).   Preferably, the connection bolt (5), the conductive contact element (6) and the ceramic are provided between the connection bolt (5) and the protection tube (3) inside the protection tube (3). The insulation sheath (7) according to any one of the preceding claims, wherein an insulating sheath (7) is provided for electrically insulating the positive electrode (41) of the heating element (4) from the protective tube (3). Glow pin plug (1).

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