EP3152494A1

EP3152494A1 - Pre-heating glow plug for heat engine

Info

Publication number: EP3152494A1
Application number: EP15730075.7A
Authority: EP
Inventors: Jean-Marc Couffignal
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-06-06
Filing date: 2015-05-28
Publication date: 2017-04-12
Also published as: WO2015185436A9; CN106415130A; FR3022012A1; FR3022012B1; WO2015185436A1

Abstract

The invention relates to a pre-heating and post-heating glow plug comprising: a conductive metal sleeve (130) fixed around the rear of the heating cartridge (110), a metal fitting (150) provided with a thread (151) and a tool grip (152) on the outside thereof, a tubular body (140) made of a plastic material arranged over the central electrode (120), forming a tapered cylinder shape (142) with the insertion of sliding cups (170), and projecting beyond the rear of the fitting. A connector (160) is engaged over the central electrode (120) and welded in order to secure same.

Description

15 061818

Field of the invention

The present invention relates to a spark plug pre ^¬ heating or post-heating for a diesel engine com ^¬ taking a heating element connected via a central electrode to a connector through the body of the candle provided with a screw thread and a tool socket for tightening the spark plug in the engine.

State of the art

In general, such a glow plug is shown in schematic sectional view in FIG. 6. This glow plug consists of a heating cartridge 210 connected to a central electrode 220 and housed in a tubular body 230 traversed by a central electrode 220. At the rear of the tubular body 230, the spark plug comprises a primary connector 260.

The tubular body 230 connected to the cartridge 210 by an assembly zone 230 comprises at its front end a centering and sealing cone 231 to provide support and sealing of the spark plug relative to the engine block.

The tubular body continues with a smooth central portion 233 and near the rear end, the thread 234 makes it possible to screw the spark plug in the engine block by the tool catch 235 which has, for example, a six-sided shape.

Internally, the tubular body 230 traversed by the central electrode 220 comprises near the rear end an internal cone 236 and at the outer surfaces, a countersink 237. A seal 240 is housed around the electrode 220 at internal cone level 236. An electrical insulation washer 250 is placed in the countersink 237.

The connector 260 installed at the rear of the body 230 on the central electrode 220 by the crimping 262 on the knurling 223 of the rear end of the central electrode 220. The connector is applied by its front face 261 against the washer 250 electrical insulation not to come into contact with the rear portion of the tubular body 230, that is to say the part with the tool socket 235. This electric insulation washer 250 is in turn based on a part at the bottom of the worm 237 of the tubular body 230 and secondly on the seal

FIRELIGHT OF REM PLACEM ENT (RULE 26) 240 which seals with the inner cone 236 of the tubular body 230 and the central electrode 220.

The inside of the tubular body 230 around the electrode: central 220 is empty and without any contact between them.

The inside of the heating cartridge 210 is filled with an insulating powder compacted on the connection system with the central electrode 220 at its front portion 221. The heating circuit itself is not shown here.

This glow plug or post-heating has a disadvantage of being composed of a relatively large number of elements and in particular numerous tubular bodies depending on the engines to which the candles are intended.

Purpose of the invention

The present invention aims to develop preheating or post-heating bougies of simple constitution consisting of a reduced number of parts, to reduce the management of the stock and lead to more economical candles.

Description and advantages of the invention

For this purpose, the subject of the invention is a preheating plug of the type defined above,

characterized in that it comprises: a conductive metal bushing fixed around the rear of the heating cartridge, to rely on the motor, a metal coupling, externally provided with a thread and a tool socket for to be screwed into the engine, a tubular body of plastics material, overmolded by injection on the electrode between the sleeve and the cartridge forming at the rear a cylindrical reduction on which is fitted the connection applied to the front thrust against the shoulder formed by the cylindrical reduction and protruding from the rear of the coupling, a connector fitted on the central and solid electrode of the latter to bear against the edge of the electrical insulating reduction protruding from the coupling .

Advantageously, the tubular body is overmolded by injection on the central electrode between the front part of the glow plug and the rear part.

FIRE ILLE DE REM PLACEMENT (RULE 26) The glow plug (which is also used as a post-heating plug) reduces the number of parts consti ^¬ killing the spark plug and in particular the stock of tubular body which is imposed by the diversity of engines to which is applied the candle.

The constituent elements of the candle such as the ^car¬¬ heated key, the socket, the connector and the primary connector are suitable elements for all forms of candles depending on the applications. Only the length of the central electrode varies with the length of the spark plug.

In addition, the metal tubular body, anterior now formed by a tubular body of plastic or composite material, in particular injected under molded pressure allows a significant reduction in the overall cost of the glow plug.

These various modifications do not reduce the performance of the glow plug.

According to an advantageous characteristic the conductive metal sleeve protrudes from the rear of the heating cartridge and forms a gap, a chamber surrounding the front end of the central electrode, the tubular body arriving at its front end in this chamber.

According to another advantageous characteristic the shoulder of the reduction of the composite tubular body and the front of the rear connection are separated by at least one sliding cup disengaging the screwing movement of the connection of the candle and the composite tubular body.

This sliding cup disengages the torque applied to the connection used for screwing and the front end of the spark plug.

According to a particularly advantageous characteristic in this context, the shoulder of the reduction and the front edge of the connector have a conical homologous shape as well as the interposed sliding cup.

According to another advantageous characteristic, the central electrode has a roughened surface for fastening the injected material of the tubular body.

FIRE ILLE DE REM PLACEMENT (RULE 26) The subject of the invention is also a method for ^producing a glow plug (or post-heating plug) as defined above. According to this method, a preheating glow cartridge is provided with a central electrode,

- is installed on the heating element a tubular sleeve secured in the rear region of the heating cartridge and leaving an annular space beyond the back of the heating cartridge ^¬ turn of the center electrode, installing the assembly formed by the heating cartridge provided with its socket in an injection mold having the shape of the outline to be given to the glow plug, the mold being closed on the socket and on the back of the central electrode, a material is injected into the mold for forming the tubular body filling the annular volume between the sleeve and the central electrode, around the central electrode and forming the cylindrical reduction before the rear end of the central electrode, after demolding the candle blank preheating is put in place or sliding cups and the connection on the reduction of the composite body by pressing against the shoulder, and leaving the reductio n cylindrical from the back of the connector, we connect the connector on the end of the central electrode by applying the connector against the free side rear end of the sleeve and the connector is fixed to the central electrode to block the assembly thus realized.

According to an advantageous characteristic, the primary connector and the central electrode are secured by methods of welding or crimping the connector on the central electrode or else any other type of connection, for example by electromagnetic pulse assembly.

Finally, the method, characterized in that one realizes a range of glow plugs with the same heating cartridge, the same socket, the same rear connection and the same connector but the length of the central electrode and that of the body is modified tubular according to the geometrical data of the engine receiving the glow plug.

FEUI LLE OF REM PLACEM ENT (RULE 26) The method of manufacturing the glow plug or post-heating has the advantage of simplification of manufacture by removing the diversity of tubular bodies replaced by a tubular body adaptable to all lengths of preheating plugs required.

According to an advantageous characteristic, the body tubu lar ^¬ is made of PA66 is to say, highly filled with carbon or glass fibers.

Advantageously, the tubular body is housed in the cylindrical hole of the cylinder head with a very small diametral clearance so that even under the effect of the axial pressure exerted on the tubular body, unlike a tubular body of metal, this It can flambé and the wall of the hole of the cylinder head retains this buckling and retains the glow plug according to the invention, an alignment sufficient to operate in good conditions.

To avoid the shear that can cause tightening torques or loosening and the destruction of the tubular body, the friction is minimized between the conical surface of the shoulder of the tubular body and the connection through the cups, especially steel, interposed and allowing to slide. The surface of the cup or cups, of low roughness facilitate the sliding in rotation of the elements in contact and minimizes any slippage of the conical surface of the shoulder of the tubular body and consequently also reduces to a minimum the torque received by this tubular body.

drawings

The present invention will now be described in more detail with reference to an embodiment of a preheating plug and its method of manufacture shown schematically in the accompanying drawings in which:

FIG. 1 is a view in partial axial section of a glow plug according to the invention,

FIG. 2 is a view in axial section of a base assembly of the heating cartridge and of the central electrode according to the invention,

FEUI LLE OF REM PLACEM ENT (RULE 26) FIG. 3 is a view of the glow plug with its overmolded tubular body but without the connection, the cups and the connector,

FIG. 4 is a sectional view of the coupling,

FIG. 5 is a sectional view of the connector,

Figure 6 is a sectional view of a glow plug: known.

Description of Embodiments of the Invention

By convention and to simplify the description of the glow plug and its manufacturing process, the candle has an axis xx which is an axis of rotation symmetry and the front end AV of the candle is the one located on the side of the chamber combustion engine, the rear end being that of the electrical connection by the connector of the customer, that is to say, in general the manufacturer.

According to Figure 1 the glow plug 100 for a heat engine consists of a heating cartridge 1 10 connected by a central electrode 120 to a connector 160 through the body of the candle constituted by a sleeve 130, followed by a body tubular 140 of plastic material receiving at the rear one or more cups and a connector 150. The rear end is provided with a connector 160.

The ceramic or metallic heating cartridge (indifferently metal or ceramic heater) 1 10 is not detailed. It comprises an electrically conductive filament, heated on the one hand, to the ground via the socket 130 and on the other hand to the positive pole of the power supply source by the central electrode 120 and the connector 160.

The socket 130 is an electroconductive metal sleeve having at the front end a conical portion 131 to serve as a support for the motor (engine block) performing in addition to this mechanical support also the electrical contact between the heating cartridge 110 and the mass of the network power. For this, the heating cartridge 1 10 externally has a contact corresponding to one end of the heating filament. This contact is connected to the socket 130 by its physical contact with the socket 130.

FEUI LLE OF REM PLACEM ENT (RULE 26) According to the embodiment shown, the sleeve 130 protrudes from the rear end of the heating cartridge 1 10 thus forming an annular chamber 132 around the front end 121 of the central electrode 120 connected to the heating cartridge 1 10.

The body of the candle holder a fitting 150 provided OUTSIDE ^¬ quently with a thread 151 and a tool outlet 152, for example a hexagon, for screwing into the engine cylinder head. The frustoconical front portion 131 of the sleeve is spaced from the thread 151 depending on the characteristics of the engine block which. receives the glow plug.

A tubular body 140 of non-conductive plastic material is engaged between the annular chamber 132 of the sleeve 130 and the connection 150, which is also metallic. The tubular body 140 has a front end 141 coming into the chamber 132 of the socket. This end continues with the tubular main part of the body 140 whose sec ^¬ tion is preferably circular corresponding to the circular section of the sleeve 130. At the rear, the tubular body 140 continues with a reduction 142 of reduced diameter for The separating and sliding cups 170 are interposed between the shoulder 143 of the tubular body 140 and the front surface 153 of the connector 150 to prevent the screwing movement from causing the front part of the spark plug. The surface 143 of the shoulder of the tubular body 140 of frustoconical shape, as well as the front end 153 of the connector 150 and also where the separation and sliding cups 170 are interposed between the shoulder 143 of the tubular body 140 and the front surface 153 of the connector 150 to prevent the screwing movement from causing the front part of the candle. The surface 143 of the shoulder of the tubular body 140 of frustoconical shape, as well as the front end 153 of the connector 150 and also where the separation cups 170. The tubular body 140 is preferably attached to the central electrode 120 whose outer surface 122 is roughened, for example by knurling. This rough surface extends only over the portion in contact with the tubular body 140, the rear end 123 of the central electrode 120 is smooth and perfect.

FIRE ILLE DE REM PLACEMENT (RULE 26) cylindrical to receive the two mold half to ensure sealing during injection pressure plastic.

FIG. 1 shows that the cylindrical reduction 142 of the tubular body 140 protrudes from the rear surface 154 of the fitting 150 'over a length 144 to thereby create an electrical isolation space between the metal connector 150 and the primary connector 160 which avoids / saves any other means of additional electrical insulation. This figure 1 shows again that the plastic overmolding also avoids / saves the seal.

FIGS. 2 to 5 make it possible to describe a preferred method for manufacturing the glow plug 100 according to FIG.

Initially, (FIG. 2) after having made separately the heating cartridge 110 and fixed thereto the central electrode 120 of appropriate length, depending on the glow plug to be produced, it is installed on the back of the cartridge 110, the socket 130 by making electrical contact with the heating cartridge 1 10 for grounding.

Next (FIG. 3), the tubular body 140 having the cylindrical shape or appropriate form of revolution is produced in an injection mold. The tubular body 140 is made of plastic. During the injection, the fluid mass enters the chamber 132 formed by the sleeve 130 and at the rear the injection mold has a shape corresponding to the sleeve 142 to be made to receive the connection 150, that is to say , a cylindrical reduction 142 as a function of the inside diameter of the coupling 150 to be received. Closing the half-molds on the outer cylindrical surface 133 of the sleeve 130 and on the cylindrical surface of the rear end 123 of the electrode seals during injection.

The shoulder 143 formed between the tubular body 140 in its main part and its cylindrical reduction 142 is preferably conical.

The coupling 150 is shown in section in FIG. 4 shows its frustoconical front face 153 allowing it to rest centrally on the separation cup (s) 170 and the rear of the tubular body 140 around its cylindrical reduction 142.

FEUI LLE OF REM PLACEM ENT (RULE 26) According to FIG. 6, the conductive metal primary connector 160 is provided with a through passage 161 with the diameter of the central electrode 120 or at least its end 123 which does not have to be roughened.

The connector 160 has a front face 162 to bear against the end 124 of the cylindrical reduction and externally a mooring collar 163. This mooring flange 163 delimits the outer surface 164 of the primary connector 160 which receives the connector manufacturer specific to each engine manufacturer and each type of engine. This manufacturer connector is not represented.

After assembly of the coupling 150 on the sleeve 142, preferably with the interposition of one or more separating washers 170, the primary connector 160 is put in place by tightening the assembly and finally blocking it by the welding 180 of the end 164 of the central electrode 120 to the connector 160 preferably by a laser beam in the axis xx of the candle through the rear opening 161a that leaves the through passage 161. Thus does not deform the outer surface 164 which receives the connector manufacturer.

The glow plug or post-heat 100 is then complete.

The method of producing the glow plug can be stated as follows:

a heating cartridge 110 of glow plug 100 is made with central electrode 120,

on the heating cartridge 110 is installed a tubular sleeve 130 fixed in the rear region of the heating cartridge 110 and leaving an annular volume 132 beyond the rear of the heating cartridge 1 10 around the central electrode 120, it is installed the assembly formed by the heating cartridge 110 provided with its sleeve 130 in an injection mold having the shape of the outline to be given to the glow plug, the mold being closed on the sleeve 130 and on the rear end 123 of the central electrode 120,

FIRELIGHT OF REM PLACEM ENT (RULE 26) injecting a material into the mold to form the body tabu ^¬ lar 140 filling the annular volume between the sleeve 130 and the center electrode 120, around the center electrode and forming the cylindrical reduction 142 before the rear end 123 of the central electrode 120,

after demolding the preheating plug blank is placed the cups 170 followed by the coupling 150 on the reduction of the composite body by pressing against the shoulder, 143, and leaving behind the rear end 144 the cylindrical reduction (142) of the back 154 of the fitting 150,

the connector 160 is connected to the end 123 of the central electrode 120 by applying the connector 160 against the free side of the sleeve 142 and the connector 160 is fixed to the central electrode 120 to block the assembly thus produced.

In particular :

one or more sliding cups 170 are interposed between the shoulder 143 of the tubular body 140 and the front 153 of the fitting 150.

The mounting of the glow plug or post-heating in the cylinder head of the engine, the body 140 is put in compression by the screwing of the connector 150 and the support of the centering cone 131 in the cylinder head.

The method described above has the advantage of always using the same basic elements whatever the dimensions of the glow plug to achieve. These basic elements are the heating cartridge 1 10 with the sleeve 130 and the central electrode 120 as well as the connection 150 and the primary connector 160. The only modification of one type of candle to another will be the length of the central electrode 120.

Then, with such elements the method described above will apply in injection molds of length adapted to the length of the tubular body 140 to achieve.

LIGHT OF INVESTMENT REMINDER (RULE 26) NOMENCLATURE

100 Glow plug or post-heat according to the invention

110 Heating cartridge (ceramic or metallic)

120 Central electrode

121 Front end of the center electrode

122 rough outer surface

123 Rear end of the center electrode

124 Welding end of the center electrode

130 Bushing

131 Centering cone

132 Annular chamber

133 Outside cylindrical surface

140 Tubular body

141 Front end of the tubular body

142 Cylindrical reduction

143 Shoulder

144 Exceeding

150 Connection

151 Threading

152 Tool socket

153 Front end

154 Rear end

160 Connector

161 Hole opening or crossing

161a Rear end through hole

162 Front support surface

163 Clamp connector manufacturer

164 Outside surface primary connector

170 Separation cups

180 Welding

200 Glow plug or post-heat according to the state of the art

210 Heating cartridge

FIRE ILLE DE REM PLACEMENT (RULE 26) EP2015 / 061818

12

220 Central electrode

221 Front end of the center electrode

222 Central part of the central electrode

223 Knurling the rear end of the center electrode

230 Tubular body

231 Centering and sealing cone

232 Hot-cartridge assembly area

233 Smooth central part of the tubular body

234 Threading of the tubular body

235 Tubular body tool socket

236 Internal cone

237 Lamage

240 Gasket

250 Electric insulation washer

260 Connector

261 Front of the connector

262 Crimping the connector

263 Customer Connector Hanging Collar

264 Cylinder of contact

XX Main axis of the candle 200 according to the state of the art

AV Engine side combustion chamber

AR Connector side manufacturer

SUBSTITUTE SHEET (RULE 26)

Claims

R E V E N D I C A T IO N S

1 °) Preheating spark plug for a heat engine comprising:

- a heating cartridge connected by a central electrode to a connector through the body of the spark plug provided with a screw thread and a tool socket for tightening the spark plug in the engine, glow plug characterized in that she understands :

a conductive metal bushing (130) fixed around the rear of the heating cartridge (110), for resting on the motor,

- a metal connector (150), externally provided with a thread (151) and a tool socket (152) to be screwed into the engine

a tubular body (140) of plastic material molded by injection onto the central electrode (120) and connected to the socket (130) and the cartridge (1 10)

forming at the rear a cylindrical reduction (142) on which is fitted the connection (150) applied forward thrust against the shoulder (143) formed by the cylindrical reduction (142) and protruding (144). from the back of fitting 150,

- A connector (160) fitted on the central electrode and solid thereof to bear against the edge of the reduction (142, 144) protruding from the connector (150).

2 °) Candle according to claim 1,

characterized in that

the conductive metal sleeve (130) protrudes from the back of the heating cartridge (110) and forms a chamber (132) surrounding the front end (121) of the central electrode (120), the tubular body (140) arriving by its front end (141) in this chamber (132). 3 °) Candle according to claim 1,

characterized in that

the tubular body (140) is molded by injection onto the central electrode (120) 4 °) Candle according to claim 1,

FIRE ILLE DE REM PLACEMENT (RULE 26) characterized in that

the shoulder (143) of the reduction of the tubular body (140) and the front (153) of the connector (150) are separated by at least one cup-glis ^¬ ment (170) detaching the screwing movement of the coupling of candle and the tubular body (140).

5 °) Candle according to Claim 4,

characterized in that

the shoulder (143) of the reduction (142) and the leading edge (153) of the fitting (150) have a conical homologous shape as well as the sliding cup (170) interposed.

6 °) Candle according to claim 3,

characterized in that

the central electrode (120) has a roughened surface for hooking the injected material of the tubular body (140).

7 °) A method of producing a glow plug according to claims 1 to 4,

characterized in that

a heater cartridge (110) for a glow plug (100) provided with a central electrode (120) is produced,

a tubular socket (130) fixed in the rear region of the heating cartridge (1 10) is installed on the heating cartridge (1 10) and leaving an annular space (132) beyond the rear of the heating cartridge (1). 10) around the central electrode (120), is installed the assembly formed by the heating cartridge (1 10) provided with its sleeve (130) in an injection mold having the shape of the outline to give the candle of preheating, the mold being closed on the sleeve (130) and on the back of the central electrode (120),

injecting a plastic material into the mold to form the tubular body (140) filling the annular space between the socket (130) and the center electrode (120) around the electrode

FEUI LLE OF REM PLACEM ENT (RULE 26) central and forming the cylindrical reduction (142) before the rear end 123 of the central electrode 120,

after demolding the preheating plug blank, the fitting (150) is placed on the reduction of the tubular body by pressing it against the shoulder, and leaving the cylindrical reduction (142) over its length (144). from the back (154) of the fitting (150),

the connector (160) is connected to the end (123) of the central electrode by applying the connector (160) against the free side of the sleeve (142) and the connector (160) is fixed to the central electrode (120). ) to block the assembly thus produced.

8 °) Method according to claim 7,

characterized in that

one or more sliding cups (170) are interposed between the shoulder (143) of the tubular body (140) and the front (153) of the fitting (150).

Method according to Claim 7,

characterized in that

the central electrode (120) is welded (180) to the connector (160).

10 °) Method according to the claim,

characterized in that

a range of glow plugs (100) are made with the same heat cartridge (110), the same socket (130), the same rear connector (150) and the same connector (160) but the length of the electrode is modified central (120) and that of the tubular body (140) according to the geometrical data of the engine receiving the glow plug (100).

FEUI LLE OF REM PLACEM ENT (RULE 26)