JP2015004506A - Sheath type glow plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheath type glow plug for an internal combustion engine, capable of being easily and inexpensively manufactured by simplifying electric contact connection of a plug, and dispensing with insulating filler powder.SOLUTION: A sheath type glow plug for an internal combustion engine includes a housing 1 and a ceramics heater plug 2, a connection pin 4 is disposed in the housing 1, and a second electric contact connecting part 6 of the heater plug 2 is connected to the housing 1 through a supporting pipe 3. The connection pin 4 and a first electric contact connecting part 7 of the ceramics heater plug 2 are electrically connected through a sleeve 8.

Description

  The present invention relates to a sheath type glow plug for an internal combustion engine.

  According to the prior art, sheathed glow plugs with ceramic heater plugs are already known. Patent Document 1 discloses a sheath-type glow plug including a ceramic heater plug and a connection pin, and electrical contact connection between the connection pin and the ceramic heater plug is performed via a conductive wire. . In this case, the conductive wire is embedded in the insulating powder in order to avoid a short circuit due to the contact of the conductive wire with the housing.

European Patent Publication No. 1707883

  On the other hand, the sheath-type glow plug of the present invention having the features of claim 1 is a simplified contact connection of a ceramic glow plug that can be manufactured easily and inexpensively without the insulating filler powder. Provides the advantage of enabling Furthermore, the sheathed glow plug according to the present invention is more robust against thermal and mechanical stresses. This is because the sleeve provides a more robust connection than the conductive wire. The robust and rigid connection between the connecting pins eliminates the need to fill the sheathed glow plug with insulating powder, which eliminates at least one process step during manufacture and thus significantly reduces costs. In some cases, the manufacturing process is accelerated.

  By means of the dependent claims, preferred embodiments and improvements of the sheath-type glow plug according to the independent claims are possible.

  According to a first preferred embodiment, the sleeve has a correction element that allows the axial length between the connection pin and the first electrical contact connection of the ceramic heater plug to be corrected. Correction is possible.

  It is particularly preferred if the correction element of the sleeve is configured as a corrugated tube or if the entire sleeve is configured as a corrugated tube. The corrugated tube allows axial length correction in a simple and inexpensive manner, while at the same time the corrugated tube provides sufficiently high rigidity to support the housing or at least partially disposed within the housing Contact with the pipe is obtained, and thus short-circuiting is reliably avoided.

  Optionally, it is preferred if the correction element has a spring acting in the axial direction. Such a spring compensates for the change in length between the connecting pin and the ceramic heater plug based on the thermal load, and also the mechanical load due to, for example, engine vibration or combustion pressure waves.

  According to another preferred embodiment, a push-in deformed portion is formed in the ceramic heater plug, and a molded portion of the support pipe is engaged in the push-in deformed portion. In addition to the friction-coupled connection, the indented deformation section additionally provides a shape-coupled connection between the support pipe and the ceramic heater plug, thereby providing an improved and reliable contact connection. It is particularly preferable that the indentation deformed portion is formed at the second electrical contact connection portion of the ceramic heater plug. This is because this provides an at least partially shape-coupled contact connection between the ceramic heater plug and the support pipe.

  Similarly, preferably, a second indentation deformed portion is formed in the ceramic heater plug, and a molded portion of the sleeve is engaged in the second indentation deformed portion. Also in this case, it is particularly preferable if the second push-in deforming portion overlaps with the contact connection portion, that is, in this case, the first contact connection portion. Also in this place, the second push-in deformation provides an at least partly shape-coupled connection in addition to the friction-coupled connection, whereby the contact connection is overall more robust and better. .

  Further, preferably, a push-in deformed portion is formed in the connection pin, and a concave portion of the sleeve is engaged in the push-in deformed portion. With this further third indentation, the contact connection is improved not only at the ceramic heater plug but also at the connection pin.

  In addition, it is preferable if an insulating element is arranged between the support pipe and the sleeve. This insulation element reduces the risk of deformation of the sleeve or the support pipe, since the entire composite member consisting of the support pipe and the sleeve has a significantly higher rigidity. In this case, it is particularly preferable that the support pipe is formed with a fourth indentation deforming portion, and the fourth indentation deforming portion is disposed at a height position of the third indentation deforming portion in the connection pin. Thereby, the insulating element is fixed in a shape-coupled manner by the third push-in deformation part and the fourth push-in deformation part.

  Embodiments of the invention are illustrated in the drawings and are described in detail below.

It is sectional drawing of the sheath type glow plug by this invention provided with the ceramic heater plug.

  Preferred embodiments described in the characterizing portion of the present invention and other claims will be described in detail below with reference to the embodiments shown in the drawings.

  FIG. 1 shows a section on the combustion chamber side of a sheath type glow plug according to the present invention. The sheath-type glow plug has a housing 1 in which connection pins 4 for electrical contact connection are arranged. The sheath-type glow plug further includes a ceramic heater plug 2, and the heater plug 2 is disposed concentrically with respect to the connection pin 4 on an extension line of the central axis 15 of the sheath-type glow plug 20. In this case, the tip 22 of the ceramic heater plug 2 on the combustion chamber side protrudes from the housing 1. A support pipe 3 is arranged between the housing 1 and the ceramic heater plug 2, and the support pipe 3 is a friction coupling (constraint by friction) type, a shape coupling (constraint by shape) and / or a material coupling (material). Are connected to the housing 1 and the ceramic heater plug 2. The connection pin 4 has a pushing deformation portion 12 at an independent end on the side facing the ceramic glow plug 2, and this pushing deformation portion 12 is hereinafter referred to as a third pushing deformation portion 12. The ceramic heater plug 2 has a pressing deformation portion 10 at an end portion facing the connection pin 4, and the pressing deformation portion 10 is hereinafter referred to as a second pressing deformation portion 10. The ceramic heater plug 2 further has an indentation deforming portion 9, and the indentation deforming portion 9 is closer to the front end portion 22 on the combustion chamber side than the second indentation deforming portion 10 along the ceramic heater plug 2. Placed in position. A sleeve 8 is disposed between the connection pin 4 and the ceramic heater plug 2, and the sleeve 8 is fixed to the connection pin 4 and the ceramic heater plug 2. For this purpose, the end portion of the sleeve 8 facing the connection pin 4 is engaged in the third push-in deforming portion 12, and the end portion facing the ceramic heater plug 2 is pushed in the second push-in portion. The deformable portion 10 is engaged. Furthermore, the sleeve 8 is configured to be spring-elastic in the axial direction, so that longitudinal changes due to thermal expansion can be corrected in the axial direction, that is, along the central axis of the sheath-type glow plug. In this case, the sleeve 8 has sufficient rigidity to correct the axial displacement that may occur or to correct the lateral force between the connecting pin 4 and the ceramic heater plug 2 that is generated by the combustion pressure. And has sufficient rigidity to reliably avoid contact with the housing 1 or the support pipe 3. Therefore, it is not necessary to fill the housing 1 with the insulating powder.

  The ceramic heater plug 2 is surrounded by a metal support pipe 3 and forms a negative electrode of the sheath type glow plug together with the housing 1. An electrical contact connection point 6 for electrical contact connection with the negative electrode is provided on the outer periphery of the ceramic heater plug 2, and this electrical contact connection point 6 is located in the push-in deformation part 9. ing. In this case, the pushing deformation portion 9 is configured as an annular recess provided in the ceramic heater plug 2.

  In order to make an electrical contact connection with the positive electrode, a contact connection point 7 is formed on the cylindrical projection 5 of the ceramic heater plug 2, and this contact connection point 7 is referred to as a first contact connection point 7. The The first contact connection point 7 is located in the second push-in deformation part 10.

  The electrical contact connection between the ceramic heater plug 2 and the negative electrode is made through the support pipe 3. In this case, the second electrical contact connection portion 6 is conductively connected to the support pipe 3, and the support pipe 3 Is electrically connected to the housing 1. In a preferred form, the support pipe 3 has a forming part in the region of the second electrical contact connection 6 which engages in the indentation deformation part 9 of the ceramic heater plug 2. Preferably, the support pipe 3 is pushed into the push-in deformation part 9 of the ceramic heater plug 2 in this region, whereby a shape-coupled connection is obtained.

  The first contact connection portion 7 is formed on a cylindrical protrusion 5 of the ceramic heater plug 2, and the cylindrical protrusion 5 is located in a region protruding beyond the end of the housing 1. It has a smaller diameter than the plug 2. With such a configuration, a radial distance between the first contact connection portion 7 and the inner wall of the support pipe 3 is ensured. In this case, the first contact connection portion 7 is formed in a push-in deformed portion configured as an annular recess on the outer peripheral surface of the ceramic heater plug 2, similarly to the second contact connection portion 6.

  In order to electrically connect the first contact connection point 7 to the connection pin, the axially spring-elastic sleeve 8 is configured, for example, in the shape of a corrugated tube. For example, the sleeve 8 is pushed into the second push-in deformed portion 10 by an annular recess, thereby at least partly connecting the shape of the sleeve 8 and the ceramic heater plug 2. By realizing the connection, it is fixed to the cylindrical protrusion 5 of the ceramic heater plug 2 by the end section on the heater plug side. The connection pin 4 has a third indentation deformable portion 12 at the end on the side facing the ceramic heater plug 2. The sleeve 8 is a recess, and is pushed into a third push-in deforming portion 12 configured as an annular recess, for example. In order to electrically insulate the positive electrode, an insulating element 11, for example in the form of an insulating ring, is arranged between the support pipe 3 and the sleeve 8 in the region of the connection pin 4. Since the insulating element 11 reliably cuts off the electrical connection between the sleeve 8 and the support pipe 3, no current flows along this connection. In this case, the insulating element 11 is elastically deformable or plastically deformable in a suitable manner and may be glued to the support pipe and / or sleeve in order to obtain a good fixation. The support pipe 3 has an end section on the side of the connection pin that is fitted on the insulating element 11, and in this case, the support pipe 3 is formed with a fourth indentation deformation portion 13, and this fourth indentation deformation The part 13 presses the insulating element 11 against the sleeve 8. The composite consisting of the support pipe 3, the insulating element 11 and the sleeve 8 results in a sufficiently stiff member that forms a substantially axially rigid connection between the connection pin 4 and the support pipe 3.

  Alternatively, the sleeve 8 may have a different shape than the corrugated tube, which is configured in a spring-elastic manner beyond the elasticity of the material in the axial direction. Therefore, the sleeve 8 has, for example, a spring element incorporated in the sleeve 8 between the engaging portion of the sleeve 8 in the third pushing deformation portion 12 and the engaging portion of the sleeve 8 in the second pushing deformation portion 10. You can do it.

  Further, the single or plural indentation deforming portions 9, 10, 12, 13 may be omitted, and fixing at the contact connection portion may be performed by material coupling and / or friction coupling. In addition, it is also possible to provide an insulating material in the sleeve 8 between the connection pin 4 and the ceramic heater plug 2 in order to avoid an electrical short when the sleeve 8 is bent.

  Even if the proposed structure does not necessarily require insulating powder in the housing 1, as an additional safety measure, insulating powder can be used in the housing 1, in particular between the support pipe 3 and the sleeve 8 and / or the support pipe 3. The area between the housing 1 and the housing 1 can be filled.

DESCRIPTION OF SYMBOLS 1 Housing 2 Ceramic heater plug 3 Support pipe 4 Connection pin 5 Projection part 6 2nd electrical contact connection part 7 1st contact connection part 8 Sleeve 9 Pushing deformation part 10 2nd pushing deformation part 11 Insulating element 12 1st 3 indentation deformation part 13 4th indentation deformation part 15 central axis 20 sheath type glow plug 22 tip part

Claims (12)

A sheath type glow plug for an internal combustion engine, comprising a housing (1) and a ceramic heater plug (2), wherein a connecting pin (4) is disposed in the housing (1), and the ceramics The heater plug (2) has a first electrical contact connection location (7) and a second electrical contact connection location (6), and the second plug of the ceramic heater plug (2). In the type in which the electrical contact connection (6) is connected to the housing (1) of the sheath-type glow plug via a support pipe (3),
The connection pin (4) and the first electrical contact connection point (7) of the ceramic heater plug (2) are electrically connected via a sleeve (8). A sheathed glow plug.   The sheath-type glow plug according to claim 1, characterized in that the sleeve (8) is fixed to the connection pin (4) and the ceramic heater plug (2).   The sleeve (8) has a correction element, by which the connection pin (4) and the first electrical contact connection point (7) of the ceramic heater plug (2) are connected. The sheath-type glow plug according to claim 1 or 2, characterized in that the axial length can be corrected between them.   The sheath-type glow plug according to claim 3, characterized in that the correction element in the sleeve (8) is configured as a corrugated tube.   The sheath type glow plug according to claim 3, wherein the correction element has a spring acting in an axial direction.   The sheath-type glow plug according to claim 1 or 2, characterized in that the entire sleeve (8) is configured as a corrugated tube.   A pushing deformation part (9) is formed in the ceramic heater plug (2), particularly in the second electrical contact connection point (6), and the support pipe (3) is formed in the pushing deformation part (9). The sheath-shaped glow plug according to any one of claims 1 to 6, wherein the molded portion is engaged.   The ceramic heater plug (2), in particular, the first electrical contact connection point (7) is formed with a second indentation deformed portion (10), and the second indented deformable portion (10) The sheath-type glow plug according to any one of claims 1 to 7, wherein a molded portion of the sleeve (8) is engaged with the sheath-type glow plug.   The connection pin (4) is formed with a third pushing deformation portion (12), and the concave portion of the sleeve (8) is engaged in the third pushing deformation portion (12). The sheath-type glow plug according to any one of claims 1 to 8.   10. An insulating element (11), in particular an insulating ring, is arranged between the support pipe (3) and the sleeve (8), according to any one of the preceding claims. Sheath type glow plug.   The support pipe (3) is formed with a fourth indentation deforming portion (13), and the fourth indentation deforming portion (13) is higher than the third indentation deforming portion (12) in the connection pin. The insulating element (11) is fixed in a shape-coupled manner by the third pushing deformation part (12) and the fourth pushing deformation part (13). The sheath-type glow plug according to claim 9 or 10.   12. The sheath-type glow plug according to any one of claims 6 to 11, characterized in that one or more of said indented deformation parts (9, 10, 12, 13) are configured as annular recesses.

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