Glow plug

Abstract

The invention relates to a glow plug comprising a housing, a ceramic pencil-type glow element which projects from the housing with a first end and is arranged inside the housing with a second end, a feed line which is arranged in the housing and leads to the pencil-type glow element, and a sleeve-type element which surrounds a section of the pencil-type glow element projecting from the housing. The invention is characterized in that the pencil-type glow element has a section surrounded by the housing which section tapers towards the second end, the pencil-type glow element is encircled by a contact element in the housing, which contact element has a section that narrows towards the second end of the pencil-type glow element, said narrowing section encircling at least a subsection of the tapered section of the pencil-type glow element. The invention further relates to a method for producing said glow plug.

Claims

1. A glow plug, comprising: a housing; a ceramic glow pencil having a first end projecting from the housing and a second end disposed in the housing, the ceramic glow pencil comprising an inner conductor and an outer conductor; a feed line arranged in the housing and leading to the ceramic glow pencil; and a steel sleeve enclosing a first section of the ceramic glow pencil projecting from the housing; wherein the ceramic glow pencil comprises a second section that is surrounded by the housing and tapered towards the second end; and a contact element disposed in the housing and around the second section of the ceramic glow pencil where the ceramic glow pencil projects through the contact element, wherein the contact element includes a narrowing section configured to surround the tapering of the second section of the ceramic glow pencil forming an electrical connection between the contact element and the second section of the ceramic glow pencil, and wherein an annular space between the contact element and the tapered second section comprises an increasing gap between the contact element and the second section of the ceramic glow pencil when moving away from electrical connection, where the annular space is configured to act as a buffer to accept a braze or a solder; and wherein the contact element is made from steel, wherein the steel of the sleeve is a different material in comparison to the steel of the contact element.

2. The glow plug according to claim 1 wherein the contact element is brazed or soldered to the ceramic glow pencil at the annular space.

3. The glow plug according to claim 1 wherein the contact element abuts to the sleeve.

4. The glow plug according to claim 1 wherein the contact element and the sleeve overlap each other.

5. The glow plug according to claim 1 wherein the feed line is surrounded by a second sleeve in the housing.

6. The glow plug according to claim 5, wherein the contact element abuts to the second sleeve.

7. The glow plug according to claim 5 wherein a vibration damper is arranged between the second sleeve and the housing.

8. The glow plug according to claim 1 wherein the sleeve is connected to the housing via a sealing element.

9. The glow plug according to claim 1 wherein the sleeve and the contact element are manufactured from different materials.

10. The glow plug according to claim 1 wherein the contact element comprises at least one cylindrical inner surface which is arranged adjacent to the narrowing section.

11. The glow plug according to claim 1 wherein the ceramic glow pencil is press-fitted into the sleeve.

12. The glow plug according to claim 1, wherein the contact element is welded to the sleeve.

13. The glow plug according to claim 1, further comprising a ceramic isolator, wherein the ceramic isolator is arranged between the inner conductor and the outer conductor.

14. A glow plug, comprising: a housing; a ceramic glow pencil having a first end projecting from the housing and a tapered section disposed in the housing, where the tapered section narrows towards a second end of the ceramic glow pencil, where the ceramic glow pencil comprises an inner conductor, a ceramic isolator and an outer conductor, wherein the ceramic isolator is arranged between the inner conductor and the outer conductor; a sleeve enclosing a first section of the ceramic glow pencil projecting from the housing; and a contact element disposed in the housing and around the tapered section where the tapered section projects through the contact element, the contact element including a narrowing section configured to surround and abut the tapered section of the ceramic glow pencil forming an electrical connection between the contact element and the tapered section of the ceramic glow pencil, wherein an annular space between the contact element and the tapered section adjacent to the narrowing section comprises an increasing gap between the contact element and the tapered section of the ceramic glow pencil when moving away from the electrical connection, where the annular space is configured to act as a buffer to accept a braze or a solder; wherein the contact element is welded to the sleeve.

15. The glow plug according to claim 14, wherein the contact element and the sleeve are made from steel, wherein the steel of the sleeve is a different material in comparison to the steel of the contact element.

16. A glow plug, comprising: a housing; a ceramic glow pencil having a first tapered end projecting from the housing and a second tapered end disposed in the housing, where the tapering of the first tapered end narrows towards the first end and where the tapering of the second tapered end narrows towards the second end, where the ceramic glow pencil comprises an inner conductor connected to an outer conductor; a metallic sleeve around the first tapered end where the first tapered end projects through the sleeve and the sleeve is configured to be adjacent to the tapering of the first tapered end; and a contact element that is made from steel and disposed in the housing and around the second tapered end where the second tapered end projects through the contact element, the contact element including a narrowing section configured to surround and abut the second tapered end forming an electrical connection between the contact element and the second tapered end of the ceramic glow pencil; wherein the sleeve and the contact element are separately manufactured and are made of different metallic materials; and wherein the sleeve and the contact element are configured to abut each other and are welded together when formed as the glow plug.

17. The glow plug according to claim 16, further comprising an annular space between the contact element and the second tapered end adjacent to the narrowing section where the annular space comprises an increasing gap between the contact element and the second tapered end of the ceramic glow pencil when moving away from the electrical connection, where the annular space is configured to act as a buffer to accept a braze or a solder.

18. The glow plug according to claim 17, including a braze or solder in the at least one circumferentially continuous annular space.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention will be illustrated in more detail by means of the drawings. Therein, components that are equal and corresponding to each other are provided with corresponding reference symbols. In the drawings,

(2) FIG. 1 is a sectional view of a ceramic pressure measuring glow plug;

(3) FIG. 2 shows heater or glow pencil variants;

(4) FIG. 3 shows contact ring variants;

(5) FIG. 4 shows inner pole head variants;

(6) FIG. 5 shows sleeve variants;

(7) FIG. 6 shows extension variants;

(8) FIG. 7 shows a heater or glow pencil variant with contact ring and inner pole head;

(9) FIG. 8 shows a heater or glow pencil variant with contact ring and inner pole head;

(10) FIG. 9 shows a heater or glow pencil variant with contact ring and inner pole head;

(11) FIG. 10 shows a heater or glow pencil variant with contact ring and inner pole head;

(12) FIG. 11 shows a heater or glow pencil variant with contact ring and inner pole head;

(13) FIG. 12 shows a heater or glow pencil variant with contact ring and inner pole head;

(14) FIG. 13 shows a heater or glow pencil variant with contact ring and inner pole head;

(15) FIG. 14 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(16) FIG. 15 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(17) FIG. 16 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(18) FIG. 17 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(19) FIG. 18 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(20) FIG. 19 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(21) FIG. 20 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(22) FIG. 21 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(23) FIG. 22 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(24) FIG. 23 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(25) FIG. 24 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(26) FIG. 25 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(27) FIG. 26 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(28) FIG. 27 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(29) FIG. 28 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(30) FIG. 29 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(31) FIG. 30 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(32) FIG. 31 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(33) FIG. 32 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(34) FIG. 33 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(35) FIG. 34 shows a heater or glow pencil variant with contact ring and inner pole head and sleeve;

(36) FIG. 35 shows a glow pencil with contact ring, inner pole head, sleeve, feed line, and glow current connection;

(37) FIG. 36 shows a glow pencil with contact ring, inner pole head, sleeve, feed line, and glow current connection;

(38) FIG. 37 shows a glow pencil with contact ring, inner pole head, sleeve, feed line, glow current connection, and extension;

(39) FIG. 38 shows a glow pencil with contact ring, inner pole head, sleeve, feed line, glow current connection, and extension;

(40) FIG. 39 is a sectional view of a further exemplary embodiment of a ceramic glow plug;

(41) FIG. 40 is a sectional view of a further exemplary embodiment of a ceramic glow plug; and

(42) FIG. 41 presents the various variants according to categories.

DETAILED DESCRIPTION

(43) FIG. 1 shows an exemplary embodiment of a glow plug according to the invention with a ceramic glow pencil I which, surrounded by a sleeve V, projects from a housing that consists of an upper housing body part X and a lower housing body part XII. The glow pencil I has an inner conductor, an outer conductor and an isolator therebetween. The glow pencil tapers towards its end arranged in the housing, preferably in a conical form. For the purpose of electrically contacting the inner conductor of the glow pencil, this end is inserted into an inner pole contact head III that is connected to a feed line IV and to which the glow pencil I is soldered.

(44) The outer conductor of the glow pencil is electrically contacted via a contact element II which, in the exemplary embodiment illustrated, is formed as a ring. The contact ring II is brazed or soldered to the glow pencil I and has a narrowing section which, in the exemplary embodiment illustrated, has a conical interior surface, and comprises a partial section (in the following connecting cone) of the conically tapering section of the glow pencil.

(45) There are two annular spaces between the contact element II and the glow pencil I, which are provided as buffers 7, 8 for receiving excessive brazing or soldering material. However, these annular spaces are, in part, filled with brazing or soldering material and, starting from one end of the contact element II, narrow towards the other end of the contact element.

(46) At one of its ends, the ceramic glow pencil I of FIG. 1 has the glow tip 1 of the ceramic glow pencil, said glow tip 1 being connected to the connecting cone 3 of the ceramic glow pencil via the feed line of the ceramic glow pencil, said connecting cone 3 being particularly shown in FIG. 2a. Said connecting cone 3 of the ceramic glow pencil is divided into a connecting cone or connecting cone section 4 for the contact ring II on the ceramic glow pencil, the isolator region 5 on the connecting cone of the ceramic glow pencil and the connecting cone or connecting cone section 6 for the inner pole head III on the ceramic glow pencil.

(47) The connecting cone 4 for the contact ring II on the ceramic glow pencil represents the outer contact; the connecting cone 6 for the inner pole head III on the ceramic pencil represents the inner contact. The contact ring II is seated on the connecting cone 4 for the contact ring II on the ceramic glow pencil; the inner pole head III is seated on the connecting cone 6 for the inner pole head on the ceramic pencil. The feed line IV which is connected to the inner pole head III is inserted into the latter.

(48) The sleeve V which, preferably, consists of a high temperature resistant metal, such as, for example, Inconel, and a further sleeve intended as extension VI are welded to the contact ring II. Therein, the sleeve V and the extension VI are positioned in relation to each other and are arranged such that they each overlap the contact ring II. The glow current connection VII is attached to the feed line IV, with the glow current connection VII, in turn, being connected to the sensor element with plug connection VIII. The sensor element VIII is a pressure sensor, with the result that the glow plug can be used to measure the pressure in the combustion chamber of an engine. A vibration damper, i.e., the damping ring IX, is mounted to the extension VI. For the purpose of positioning the damping ring IX, the further sleeve VI has a section 17 with reduced outside diameter.

(49) The upper body part X was mounted above this entity (heater rod) and connected to the sensor element VIII. A sealing element XI, for example, a bellows, is attached to the upper body part X and to the sleeve V. The sealing element XI seals the two parts against each other and radially holds them in position. The lower body part XII is attached to the upper body part X and completes the whole thing.

(50) The glow current connection VII comprises a welding hole 19 in the joint region 18 of the glow current connection, with the welding energy on the surface of the feed line IV being directed into said welding hole 19. In this manner, the material of the glow current connection VII is secondarily melted-on by the molten mass of the feed line IV instead of being boiled away.

(51) A wrap consisting of an active brazing or soldering material wetting the ceramics is pushed into position in the cone region of the inner pole head III. The ceramic glow pencil is introduced and pressed into this pair of parts. This combination is placed into a precisely manufactured apparatus. An apparatus guides and presses the two components to be brazed or soldered into position in relation to each other from above.

(52) For the purpose of the brazing or soldering operation, the immediate environment of the components is hermetically sealed, for example, by means of a glass casing which is put over the apparatus, wherein a gripper serves as a cover. Argon is circulated into the cavity from below, and the argon escapes through small openings (1 mm hole in the cover, or labyrinth around the grippers) at high speed. After a defined precirculation time has elapsed, the inner pole head is heated until the solder has wetted the two components. In order to obtain uniform heating of the ceramic pencil, a heating casing made of temperature-resistant steel, for example, Inconel can be placed around the glow pencil and also heated in the process. In the next work step, a comparable procedure is followed for the component that has been made and the contact ring II. To achieve this, a suitable brazing or soldering wrap is also positioned into the contacting ring II, the combination is pressed together and is circulated around with argon, heated and brazed or soldered.

(53) The glow pencil thus contacted is a multiple-use part. If mechanically supplemented in an appropriate manner, it can be used as a glow plug in pre-combustion chambers, flame glow plugs and engine-independent air heating systems. If provided with a protective sleeve for the ceramic pencil as a safeguard against coking and an inner pole extension, it can be supplemented to form a ceramic glow plug for high-speed self-igniting engines or, along with a feed line IV and an extension VI, installed to form a heater rod for a pressure measuring glow plug. To achieve this, the sleeve V and the extension VI are clamped into an apparatus. The contacted glow pencil is inserted so that, when the sleeve and the extension are positioned, it will be positioned therebetween. The apparatus now positions the sleeve and the extension in exact relation to the axis and presses the components into each other. Thus guided, the components are laser-welded to each other while being turned. The heater rod that is obtained is straight and, along with a sensor element with plug connection, damping ring, upper body part, bellows, and lower body part, is assembled, e.g., to form a CPSG in known manner.

(54) FIG. 2 discloses three different heater or glow pencil variants. In essence, variant Ia has a cylindrical design. Variant Ib comprises a turned-on tip. Variant Ic shows a conical heater tip.

(55) FIG. 3 shows four different contact ring variants IIa, IIb, IIc and IId. The illustrated contact rings II each have a narrowing section which, preferably, has a conical form.

(56) A cylindrical section can be arranged adjacent to one side or both sides of the narrowing section, for example, in order to create an annular space as buffer for brazing or soldering material.

(57) FIG. 4 discloses five variants of inner pole heads IIIa, IIIb, IIIc, IIId, and IIIe. FIG. 5 shows seven different sleeve shapes Va, Vb, Vc, Vd, Ve, Vf, and Vg. FIG. 6 discloses extension variants VIa, VIb, VIc, VId and Vie.

(58) FIG. 7 shows a cylindrical glow pencil I without sleeve, with a contact ring IIb and a brazed or soldered-on inner pole head III. FIG. 8 shows a cylindrical glow pencil without sleeve, with a further exemplary embodiment of a contact ring IIc and an inner pole head III. FIG. 9 shows a cylindrical glow pencil without sleeve, with a contact ring IId and an inner pole head III and a solder buffer on the shaft of the inner pole head 10. FIG. 10 shows a heater or glow pencil variant with a contact ring II and an inner pole head III, wherein the glow pencil comprises a tip which is reduced in its diameter and has a so-called turned-on design. Further variants of FIGS. 10 to 34 are illustrated in FIG. 41.

(59) FIGS. 8, 9, 10, 14, 18, 22, 26, 29, and 32 show butt-welding examples of laser welding for attaching the sleeve V.

(60) FIG. 35 shows the example of FIG. 23 with connected feed line in the form of a pencil as well as a glow current connection, with a hole for laser welding in the illustrated instance. FIG. 36 shows the example of FIG. 23, wherein the feed line IV is designed in the form of a cable which is arranged at the glow current connection VII that is arranged as sleeve.

(61) FIG. 37 shows the example of FIG. 23 with connected feed line in the form of a cable, wherein the glow current connection is configured with a collar, to allow future molding in the sensor housing and extending as a simple tube section with reduction/drawing-in 17.

(62) FIG. 38 shows the apparatus of FIG. 37, however, with an extension as tube section with turned-on section 17 and a hole for producing the joint region 16. FIG. 39 shows a glow plug which comprises the following elements: ceramic glow pencil contact ring II, inner pole head III, feed line IV, sleeve V, glow current connection VII, as well as an upper body part X configured as housing and a lower body part XII. A bellows-type seal is arranged between the housing and the sleeve V. A hexagon bolt 20 which is provided for assembly in the cylinder head is arranged at the end of the glow plug that is arranged opposite from the glow pencil I, wherein said hexagon bolt 20 can be used to turn the glow plug into the cylinder head by means of the thread 21 that is arranged on the lateral area of said hexagon bolt.

(63) FIG. 39 shows schematically a further exemplary embodiment of a glow plug according to the invention with a somewhat simpler construction. While in the embodiment shown in FIG. 1 the contact element II is connected on one side to the sleeve V and on the other side to a further sleeve VI, the further sleeve is absent in the exemplary embodiment of FIG. 39.

(64) A further difference relates to the configuration of the first end of the glow pen I and of the sleeve V. The glow pin is rounded at its first end and is cylindrical therefrom up to the tapered portion at the second end. The sleeve V lies against the glow plug I only on part of its length. A ring gap is formed between a portion of the sleeve V adjacent to the contact element II and the glow pin.

(65) The housing part X has an external thread 21 and a hexagon 20 for screwing into a motor. Otherwise, this exemplary embodiment corresponds to the exemplary embodiment shown in FIG. 1, for which reason reference is made to the statements made there.

(66) FIG. 40 shows schematically a further exemplary embodiment of a ceramic glow plug in a longitudinal section. The essential difference to the exemplary embodiment explained above with reference to FIG. 39 is that a one-part housing X is used. The sleeve V is pressed into the housing X. It is also possible to weld the sleeve V with the housing X.

(67) The exemplary embodiment illustrated in FIG. 40 has the advantage of a simplified construction. However, the sleeve V is practically no longer movable relative to the housing X, so that this glow plug cannot be used as a pressure measuring glow plug. In the exemplary embodiment shown in FIG. 39, the glow pin together with the sleeve V attached to it can, however, be pushed into the housing X more or less far against a restoring force as a function of the combustion chamber so that the position of the glow plug I relative to the housing X a pressure measurement is possible.

REFERENCE SYMBOLS

(68) I Ceramic glow pencil II Contact ring III Inner pole head IV Feed line V Sleeve VI Extension VII Glow current connection VIII Sensor element with plug connection IX Damping ring X Upper body part XI Bellows XII Lower body part 1 Glow tip of the ceramic glow pencil 2 Feed line of the ceramic glow pencil 3 Connecting cone of the ceramic glow pencil 4 Connecting cone for the contact ring on the ceramic glow pencil 5 Isolator region at the connecting cone of the ceramic glow pencil 6 Connecting cone for the inner pole head on the ceramic glow pencil 7 Buffer for solder or brazing material on the cone of the contact ring 8 Buffer for solder or brazing material on the shaft of the contact ring 9 Buffer for solder or brazing material on the cone of the inner pole head 10 Buffer for solder or brazing material on the shaft of the inner pole head 11 Jointing hole for feed line at the inner pole head 12 Narrowed diameter at the sleeve 13 Tapered wall thickness at the sleeve 14 Original wall thickness of the sleeve 15 Joint region at the sleeve to the contact ring 16 Joint region at the extension to the contact ring 17 Guide region for damping ring at the extension 18 Joint region at the glow current connection 19 Welding hole at the glow current connection 20 Hexagon bolt 21 Thread