DE102012215338A1 - Starter for starting combustion engine of vehicle, has switch comprising contact elements that are in contact with switching bridge, and pyroelectric conductor material with electrical resistance in specific range at room temperature - Google Patents

Abstract

The starter (1) has an initiator relay (6) for transferring a starter pinion (2) between a disengaged position and an engaged position. An electric drive motor (5) drives the starter pinion, and a switch (11) comprises a switching bridge (13) and two housing fixed contact elements (16) that are in contact with the switching bridge. A part of the switch or a line section is connected with the contact elements made of pyroelectric conductor material. The pyroelectric conductor material has electrical resistance in range from 0.5 - 50 milliohms at room temperature.

Description

The invention relates to a starting device for an internal combustion engine according to the preamble of claim 1.

State of the art

In the DE 10 2007 036 789 A1 there is described an engine starting device having a starter pinion axially displaceable between a disengaged position and an advanced engaged position in which the starter pinion engages a ring gear of the internal combustion engine. The axial feed movement of the starter pinion is generated by means of an electromagnetic starter relay whose armature actuates a switch for switching on an electric drive motor which drives the starter pinion.

To compensate for temperature fluctuations associated with a change in the electrical resistance of the field winding of the starter relay, a thermistor element with a negative temperature coefficient is integrated into the circuit of the field winding, which has a high resistance at low temperatures and lower resistance at higher temperatures. The temperature-increasing resistance of the relay winding can be compensated.

A comparable execution is also from the DE 41 22 252 A1 as well as from the DE 41 06 247 C1 known.

Furthermore, it is known from the prior art, in the circuit of the electric drive motor to integrate a thermistor resistance with a negative temperature coefficient, which, for example, in the GB 2 292 645 A or the US 6,570,359 B2 is described. From the DE 10 2009 029 226 A1 is the use of a thermistor material in the switching element of a starter motor known. For further state of the art is still on the DE 195 09 365 A1 and the DE 197 34 410 A1 directed.

Disclosure of the invention

The invention has for its object to perform with simple measures a starting device for an internal combustion engine so that the electrical system is relieved, especially at low temperatures.

This object is achieved with the features of claim 1. The dependent claims indicate expedient developments.

The starting device according to the invention is used for starting internal combustion engines and has a starter pinion and an electromagnetic starter relay, which transfers the starter pinion between a disengaged position and an engagement position in which the starter pinion is in engagement with a ring gear of the internal combustion engine. For driving the starter pinion, an electric drive motor is provided, which is turned on by means of a switch, wherein the switch is actuated by a movement of the starter relay. The switch has a switching bridge, which is brought to turn on the drive motor in contact with two contact elements of the switch, which are arranged in the circuit of the electric drive motor. Once the switching bridge of the switch is in contact with the two contact elements, the circuit is closed and the electric drive motor is started, whereby the starter pinion is rotated and the internal combustion engine is started.

At least one component of the switch - ie the switching bridge or a contact element - or a line section connected to a contact element consists of a thermistor material (NTC - Negative Temperature Coefficient) or is provided with a Heißleitwerkstoff, for example coated.

Thermistor materials (NTC - Negative Temperature Coefficient) have due to the negative temperature coefficient in the cold state, which prevails in particular at the beginning of the starting phase, a higher electrical resistance than at higher temperatures. The thermistor material thus acts at the beginning of the starting phase as a series resistor for limiting the short-circuit current, whereby a voltage dip in the electrical system of the vehicle and a concomitant impairment of other peripherals that are supplied via the electrical system, or at least mitigated. Also, current flashovers on the commutation of the electric drive motor can be avoided, which otherwise lead to increased wear of the commutation.

The thermistor material of the invention has at room temperature a relatively low electrical resistance in the range between 0.5 mOhm and 50 mOhm. The thermistor material can basically assume all values in the stated range of values or in a restricted value range between 1 mOhm and 20 mOhm.

Thermistor materials with this compared to the prior art low electrical resistance have the advantage that on the one hand, the resistance is sufficiently high to start in the To effectively limit short circuit current. On the other hand, the electrical resistance decreases with increasing heating, so that during operation the power drop at the thermistor resistance is low.

The thermistor material is located in the circuit of the starter motor in one or more components of the switch, which is switched on or off by the starter relay. The thermistor material is embodied either as a coating of a component of the switch or as a volume element which consists of the thermistor material and is either integrated in a component of the switch or connected to the component. In principle, it is also possible for a line section, which is connected to a contact element of the switch, to consist in sections of thermistor material. The thermistor material is thus located directly in or on the switch, which is actuated by the starter relay.

Considered, for example, a coating of the switching bridge, which is actuated by a lifting armature of the starter relay and pressed against the contact elements to close the electrical circuit of the starter motor. Instead of a coating of thermistor material, the switching bridge may also be wholly or partly made of a thermistor material.

Furthermore, it is possible to provide the contact elements, at least on the face side, where the contact is made with the switching bridge, with a thermistor coating or to arrange a volume element made of semiconductor material on the contact element or to integrate it into the contact element. In principle, it is sufficient to provide a thermistor material only on or in one of the contact elements; According to a further embodiment, however, it is provided that a coating or a volume element of thermistor material is arranged on both contact elements.

Intermetallic, thermoelectric materials having a specific electrical resistance in the range between 0.1 to 10 ohm.cm and a thermal conductivity which is preferably less than 20 W / mK, in particular less than 10 W / mK at room temperature, for example Heusler and Halbheusler compounds , Skutterudites, magnesium silicides, higher manganese silicides or bismuth telluride.

Also suitable as thermistor materials are oxide materials which advantageously have a specific electrical resistance of between 0.1 .OMEGA.cm to 10 .OMEGA.cm at room temperature. The oxide materials are preferably a glass ceramic, for example an iron-containing glass ceramic. Also suitable are other oxide materials such as reduced TiO ₂ , Li-doped NiO, spinels, perovskites, for example Mn-based perovskites (La _1-x Sr _x MnO _{3 + δ} ), Cr-based perovskites (La _1-x Ca _x CrO _{3 + δ} ) or Cu-based perovskites (La _1-x Sr _x CuO _2.5-δ ). As iron-containing glasses or glass-ceramics, for example, 16Na ₂ O / 10CaO / (74-y) SiO ₂ / yFe ₂ O ₃ or (60-x) P ₂ O ₅ / (20-x) V ₂ O ₅ / 20Fe ₂ O ₃ are used.

In the case of a coating, the thermistor material can be applied by enameling on the component of the switch. In principle, however, other coating methods are also suitable, for example sol-gel methods, plasma spraying (powder and suspension), high-speed flame spraying (powder and suspension), powder spraying and sintering, screen printing and sintering, paste spraying and sintering, dipcoating and sintering, physical vapor deposition, Chemical Vapor Deposition, Aerosol Deposition etc. The thermistor material on the component of the switch expediently has an electrical series resistor in the range between 0.5 mΩ and 50 mΩ. The layer thickness applied by way of the coating method is preferably in the range 0.1 μm to 500 μm.

It may also be expedient to apply the thermistor material in the form of a resistance field to the component of the switch, for example to the switching bridge, wherein the resistance field covers only a portion based on the connection between the two contact elements, which is bridged by the switching bridge. Preferably, each contact element is associated with a resistance field of thermistor material, wherein the two resistance fields are not connected to each other, so that the current flows with closed contacts on each resistance field and the intermediate portion of the switching bridge. At cold temperatures at the beginning of the starting process, the series resistance in the thermistor material in the resistance field is high, which limits the short-circuit current. As the current flows, the resistance fields heat up so that the series resistance is significantly reduced and the current flow is not or at least substantially hindered.

According to a further advantageous embodiment, the armature of the starter relay adjusts the movable part of the switch. The longitudinal axis of the armature and the longitudinal axis of the switch extend coaxially, wherein the switch is expediently displaced rigidly from the armature of the starter relay in the direction of the contact position. The switch is further preferably subjected to a force by a spring element in the external contact position, so that against the force of the spring element, the switch must be adjusted by the armature in the direction of contact position. The anchor goes back into the Starting position back, the switch is moved by the spring element from the contact position to the external contact position. It is possible both a fixed coupling between the armature and the switch and a loose concern of the switch on the front side of the armature or a component connected to the armature. The spring element is advantageously arranged on the side facing away from the armature and is supported on a portion of the starter relay housing.

Further advantages and expedient embodiments can be taken from the further claims, the description of the figures and the drawings. Show it:

1 in a schematic representation of a starting device for an internal combustion engine with a starter relay for axially adjusting a starter pinion and an electric drive motor for driving the starter pinion, wherein the drive motor is turned on by a switch which is adjusted by the armature of the starter relay,

2 a section through the starter relay,

3 a switch for switching on the electric drive motor, the switch being integrated in the starter relay,

4 a plan view of the front side of the switch according to 3 ,

In the figures, the same components are provided with the same reference numerals.

In the 1 illustrated starting device 1 for starting an internal combustion engine has a starter pinion 2 on, which engages with a sprocket 3 to bring the internal combustion engine. The starter pinion 2 is on a wave 4 axially displaceable between a disengaged position and the engaged position with the sprocket 3 to move. The wave 4 is powered by an electric drive motor 5 driven, the starter pinion 2 is on the wave 4 mounted axially displaceable, but rotatably with the shaft 4 coupled.

The axial feed movement of the starter pinion 2 is using a starter relay 6 accomplished, which is designed as an electromagnetic actuator and an axially displaceable armature 7 in a relay housing, wherein the armature 7 via an engaging lever 8th kinematically with the starter pinion 2 is coupled. The starter relay 6 has coils that pass over a power line 9 be energized, whereupon the anchor 7 against the force of a spring element acting on it 12 is adjusted and the engagement lever 8th the adjusting movement on the starter pinion 2 transfers. By switching off the starter relay 6 becomes the anchor 7 by the force of the spring element 12 adjusted to the starting position, accordingly also reaches the engagement lever 8th in a recessed position, which is the starter pinion 2 allows to return from the engaged position to the disengaged position.

The adjusting movement of the anchor 7 of the starter relay 6 is also used to turn on or off the electric drive motor 5 used. The drive motor 5 is via a power line 10 energized, in which there is a switch 11 which is integrated in the starter relay housing. The desk 11 has a jumper 13 and a switching axis 14 on, coaxial with the anchor 7 arranged and mounted axially displaceably in the starter relay housing. Furthermore, the switch 11 via a spring element 15 supported on the starter relay housing. The spring element 15 is on the anchor 7 opposite side on the switch 11 , The switching bridge 13 consists of an electrically conductive material to allow current flow in the contact position.

The switching bridge 13 is in contact with two contact elements when the switch is closed 16 in the circuit of the drive motor 5 , When the starter relay is actuated 6 becomes the anchor 7 adjusted, wherein the adjusting movement of the armature via the switching axis 14 on the switching bridge 13 against the force of the spring element 15 is transferred, causing the jumper 13 is adjusted from the external contact position into the contact position, in which a contact with the two contact elements 16 is made. Then the circuit is closed, the drive motor 5 is started. Once the starter relay 6 is switched off, the anchor passes 7 to the starting position, causing the switch 11 by the force of the spring element 15 is opened again.

As the sectional view according to 2 refer to the starter relay 6 in the starter relay housing 17 energizable coils 18 which generate a magnetic field which is the anchor 7 axially adjusted. The switching axis 14 is axially displaceable in the starter relay housing 17 stored and is by the spring element 15 in the non-contact position of the movable part of the switch 11 with force. Also the contact elements 16 , which are located in the circuit of the drive motor, are in the starter relay housing 17 integrated.

In the 3 and 4 is the moving part of the switch 11 each shown in individual representation. The switching bridge 13 is plate-shaped and extends transversely to the switching axis 14 , The spring element 15 rests on the switching bridge 13 on the switching axis 14 away from the side. The switching bridge 13 consists of an electrically conductive material to allow current flow in the contact position.

On the surface of the switching bridge 13 is at the positions which are in contact with contact with the contact elements 16 lie, one resistance field each 19 applied in the form of a coating of a thermistor material. The NTC (Negative Temperature Coefficient) has a higher electrical resistance at low temperatures than at higher temperatures.

By switching on the starter relay 6 becomes the anchor 7 through that in the coils 18 resulting magnetic field in the starter relay housing 17 pulled in, whereupon the switching axis 14 from the anchor 7 or one with the anchor 7 connected component against the force of the spring element 15 is moved from the external contact position to the contact position, in which the two resistance fields 19 at the jumper 13 touching the end faces of the contact elements 16 issue. The current flowing at the moment of contact making short-circuit current is due to the increased series resistance in the resistance fields 19 reduced. The flow of current heats the material of the resistance fields 19 made of thermistor material, so that the electrical resistance decreases and a largely unimpeded current flow is ensured by the electric drive motor, which can thus deliver its desired power for driving the starter pinion.

The resistance fields 19 are by way of the coating process on top of the switching bridge 13 applied. As a thermistor material for the resistance fields 19 For example, an oxide material such as a glass ceramic is considered. The coating takes place by means of a suitable coating method, for example by enameling.

The two resistance fields 19 are located on opposite sides relative to the spring element 15 and are not connected. When the contact is closed, the current thus flows through the resistance fields 19 and the intermediate section of the contact bridge 13 ,

Additionally or alternatively to a coating of the switching bridge 13 with a thermistor material NTC can be arranged in the housing fixedly arranged contact elements 16 of the switch 11 a volume element 20 be integrated from thermistor material. The volume elements 20 extend over the entire cross-section of the contact elements and are completely in the contact elements 16 integrated, so that the electric current inevitably over the volume elements 20 From thermistor material flows. This also achieves the effect that at low temperatures to limit the inrush current there is a high electrical resistance and, with increasing temperatures prevailing in normal operation, the resistance in the thermistor material drops significantly, so that only little or virtually no power loss occurs in the thermistor material ,

Optionally, only in one of the contact elements 16 a volume element 20 integrated from thermistor material. The volume element 20 can also be on one of the two end faces of the contact element 16 be arranged or, according to another embodiment, in a line section, with the contact element 16 connected is.

The thermistor material has both in the version as a coating on the switching bridge 13 as well as in the version as a volume element 20 At room temperature, an electrical resistance in the range between 0.5 mOhm and 50 mOhm.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007036789 A1 [0002]
• DE 4122252 A1 [0004]
• DE 4106247 C1 [0004]
• GB 2292645 A [0005]
• US 6570359 B2 [0005]
• DE 102009029226 A1 [0005]
• DE 19509365 A1 [0005]
• DE 19734410 A1 [0005]

Claims (13)

Starting device for an internal combustion engine, with a starter pinion ( 2 ) and a starter relay ( 6 ) for transferring the starter pinion ( 2 ) between a disengaged position and an engagement position in which the starter pinion ( 2 ) with a sprocket ( 3 ) of the internal combustion engine is engaged with an electric drive motor ( 5 ) for driving the starter pinion ( 2 ), with a switch ( 11 ), which during a movement of the starter relay ( 6 ) and the drive motor ( 5 ), whereby the switch ( 11 ) a jumper ( 13 ) and two fixed contact elements ( 16 ) and to turn on the drive motor ( 5 ) the jumper ( 13 ) in contact with the contact elements ( 16 ), wherein at least one component of the switch ( 11 ) or one with a contact element ( 16 ) connected line section ( 19 ) consists of a thermistor material or is provided with a thermistor material, characterized in that the thermistor material at room temperature has an electrical resistance in the range between 0.5 mOhm and 50 mOhm. Starting device according to claim 1, characterized in that in or adjacent to both contact elements ( 16 ) in each case a lying in the flow of current line section ( 19 ) is arranged from a thermistor material. Starting device according to claim 1 or 2, characterized in that the thermistor material is in the form of a coating which is applied to a component of the switch ( 11 ) is applied. Starting device according to claim 3, characterized in that the coating on the switching bridge ( 13 ) is applied. Starting device according to claim 3 or 4, characterized in that the coating has a layer thickness in the range 0.1 microns to 500 microns. Starting device according to one of claims 3 to 5, characterized in that the thermistor material as an enamel layer by melting or without temperature treatment as a layer produced via an aerosol deposition on the component ( 13 ) of the switch ( 11 ) is applied. Starting device according to one of claims 1 to 6, characterized in that the thermistor material in the form of a volume element ( 20 ) present in a component ( 16 ) of the switch ( 11 ) or with a component of the switch ( 11 ) connected is. Starting device according to claim 7, characterized in that the volume element ( 20 ) of thermistor material in the contact element ( 16 ) is integrated. Starting device according to claim 7 or 8, characterized in that the ( 20 ) Volume element of thermistor material the contact element ( 16 ) upstream and / or downstream. Starting device according to one of claims 7 to 9, characterized in that the volume element ( 20 ) is arranged of thermistor material outside of the starter relay housing. Starting device according to one of claims 1 to 10, characterized in that the thermistor material is an oxide material, preferably a glass ceramic, a perovskite or a spinel. Starting device according to one of claims 1 to 11, characterized in that the thermistor material is an intermetallic compound, such as a Heusler and Halbheuslerverbindung, a skutterudite, a silicide or a telluride. Starting device according to one of claims 1 to 12, characterized in that the armature ( 7 ) of the starter relay ( 6 ) the switch ( 11 ), wherein the longitudinal axis of the armature ( 7 ) coaxial with the longitudinal axis of the switch ( 11 ) runs.

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