EP3819494A1 - Magnetic switch for a starter - Google Patents

Abstract

The invention relates to a magnetic switch (6), in particular a starter relay, for a starting device (1) of an internal combustion engine (100), which has a connecting bolt (16) for a main current path of the starting device (1), and wherein an NTC resistance element ( 30) is introduced, the NTC resistance element (30) being arranged in a housing (20) of the magnetic switch and electrically connected between two parts (16.1, 16.2) of the connecting bolt (16), as well as such a starting device.

Description

The present invention relates to a magnetic switch, in particular a starter relay, for a starting device of an internal combustion engine and a starting device with such a magnetic switch.

State of the art

Internal combustion engines in motor vehicles can be started by means of an electrical machine, for example in the form of a starter. Since an electrical machine causes a high flow of current ("short-circuit current") precisely when it is starting up, voltage drops in the vehicle's electrical system can occur.

From the DE 103 17 466 A1 and the DE 10 2012 215 338 A1 Starting devices for internal combustion engines are known in which an NTC resistor is provided in the circuit of the starter or its electrical machine in order to reduce such voltage drops to a certain extent as a function of a temperature.

From the DE 41 06 247 C1 , the DE 41 22 252 A1 and the DE 10 2007 036 789 A1 Starting devices for internal combustion engines are known in which an NTC resistor is provided in the circuit of the relay, which is used to engage the starter, in order to limit the starting current in the relay.

Disclosure of the invention

According to the invention, a magnetic switch for a starting device and a starting device with the features of the independent claims are proposed. Advantageous refinements are the subject matter of the subclaims and the description below.

The invention is based on a magnetic switch, in particular a starter relay, for a starting device or a starter of an internal combustion engine, which has a connecting bolt for a main current path of the starting device. This can in particular be the connection to the vehicle battery (terminal 30) or the connection to the starter motor (terminal 45). Typically, the magnetic switch has a further connection bolt for the main current path, a winding that can be energized, a magnet armature and a contact bridge, the magnet switch being set up to move the magnet armature by energizing the winding and to contact the two connection bolts via the contact bridge in order to do so to close the main current path electrically. Typically, the magnet armature - when used with a starting device or a starter - is coupled to a starter pinion via a fork lever or in some other way in order to mesh it with a ring gear of an internal combustion engine.

A further winding can also be provided, the two windings then being able to include, in particular, a pull-in winding and a holding winding, both of which can optionally be energized separately. The pull-in winding, possibly also together with the holding winding, serves to move and engage the starter pinion. By means of the holding winding alone, the starter pinion can then possibly be held in the engaged state, for which less force is required than for engaging.

A main current path is to be understood as such a current path within the starting device which is used to energize the electrical machine (starter motor) of the starting device and sometimes has a very high current flow. An NTC resistance element is incorporated in this main current path, i.e. an NTC resistance element forms part of the main current path or the current for or through the electrical machine must flow via the connection bolt (or via both connection bolts) and via the NTC resistance element.

An NTC resistor or NTC resistor element, also known as an NTC thermistor, is a resistor or resistor element, which - in contrast to conventional conductors like most metals - has a lower electrical resistance with increasing temperature. The abbreviation NTC stands for "Negative Temperature Coefficient". NTC resistors are mostly semiconductor materials, some compound semiconductors and various metallic alloys. An NTC resistor can be produced, for example, by film casting or powder sintering. Examples include neodymium, gadolinium, lanthanum, strontium and iron oxide, individually or as a combination of several of these materials, as materials for NTC resistors. In particular, NTC resistors are in the form of ceramics and can, for example, have a cuboid shape.

Such an NTC resistance element in the main current path can thus counteract temperature-dependent effects. At low temperatures, due to the PTC effect of the winding (PTC stands for "Positive Temperature Coefficient"), a high current is present in the electrical machine when it is energized, which can lead to an undesirable voltage drop. This is compensated for by the NTC resistor element. A high resistance in the winding is also compensated for at high temperatures, since the ohmic resistance of the NTC resistance element is then low.

A common integration of such an NTC resistance element takes place via a separate housing for the NTC resistance element, which then has to be attached to the magnetic switch or its housing, for example by means of screws, possibly also using insulation elements and busbars or the like.

According to the invention it is now provided that the NTC resistance element is arranged in a housing of the magnetic switch and is also connected electrically between two parts of the connecting bolt. It has been found that sufficient functional reliability and a sufficient service life of the NTC resistor element can be achieved in this way, at least at the same level as with conventional attachment. In contrast, however, there are significant advantages with regard to the components required and thus also the cost. For example, no additional housing and no fastening means such as screws and no insulation elements or busbars are necessary.

In order to provide the NTC resistance element between two parts of the connecting bolt, a connecting bolt that is usually used can be divided into two, in particular viewed in the longitudinal direction. Both parts of the connecting bolt can then be introduced, for example screwed, separately into the housing cover, for example. The NTC resistance element can then be connected electrically in a suitable manner between the two parts of the connecting bolt.

The NTC resistance element is preferably arranged in a housing cover of the housing (i.e. the housing cover forms part of the housing of the magnetic switch). This allows a particularly simple installation of the NTC resistance element, since the housing cover is initially present separately and is only connected to the rest of the housing at one end of the assembly of the magnetic switch. In this case, the connection bolts are provided in the housing cover, which are used to connect the main circuit of the starter or its electrical machine and, in this respect, can in particular also be connected by means of the switching bridge in order to close the main circuit.

A preferred possibility of electrically connecting the NTC resistance element between the two parts of the connecting bolt is to arrange the NTC resistance element geometrically between the two parts of the connecting bolt. For this purpose, the NTC resistance element can in particular be mechanically braced and / or clamped between the two parts of the connecting bolt. In this case, it is conceivable, for example, that part of the connecting bolt is first completely introduced, for example screwed, into the housing or the housing cover. The NTC resistor element can then be introduced into the housing or the housing cover and brought into contact with the part of the connecting bolt that has already been introduced.

It is also conceivable here that the NTC resistance element (with a suitable design) is screwed to the housing or the housing cover. The other part of the connecting bolt can then be introduced into the housing or the housing cover or screwed to it, the NTC resistor element being braced between the two parts. It goes without saying that - in particular depending on the shape of the NTC resistor element - other possibilities are also conceivable for arranging the NTC resistor element (geometrically) between the two parts of the connecting bolt.

A further, particularly preferred possibility of electrically connecting the NTC resistance element between the two parts of the connecting bolt is for the NTC element to be at least indirectly against a spring element, in particular a spring, which can be acted upon with a force by means of the magnet armature. It is useful here if an insulation element is provided which is arranged between the NTC element or a supply line for this and the spring element. Such a spring element or such a spring can in particular be a so-called contact return spring for the contact bridge already mentioned above for establishing a contact in the main circuit.

Thus, the NTC resistance element is not or not necessarily arranged between the two parts of the connecting bolt; rather, suitable busbars or lines can be provided between each part of the connecting bolt and the NTC resistance element. A particular advantage of this arrangement is that when the winding of the magnetic switch is energized, the contact bridge presses against the contact return spring and this then presses against the NTC resistance element. It can thus be achieved that when the NTC resistor element is in use, or at least to a large extent, it is pressed against the housing or the housing cover. This has a positive effect on the contact resistance of the NTC resistor element and also prevents breakage.

The invention also relates to a starting device, in particular a starter, for an internal combustion engine of a motor vehicle, with an electrical machine which is set up to start the internal combustion engine, with an inventive one Magnetic switch, and with a starter pinion that can be rotated by means of the electric machine, the starter pinion being adjustable between two different positions by means of the magnetic switch, and the connecting bolt of the magnetic switch being or being provided in the main current path of the starting device.

With regard to the advantages and further preferred refinements, in order to avoid repetitions, reference is made to the statements on the magnetic switch, which apply accordingly here.

Further advantages and embodiments of the invention emerge from the description and the accompanying drawing.

The invention is shown schematically in the drawing using exemplary embodiments and is described below with reference to the drawing.

Brief description of the drawings

Figure 1

shows schematically a starting device for an internal combustion engine with a magnetic switch.

Figures 2 to 4

schematically show magnetic switches according to the invention in various preferred embodiments in a sectional view.

Embodiment (s) of the invention

In Figure 1 a starting device or a starter 1 for an internal combustion engine 100 with a magnetic switch 6 is shown schematically. The starting device 1 is used to start the internal combustion engine 100 and has a starter pinion 2 which is to be brought into engagement with a ring gear 3 of the internal combustion engine. The starter pinion 2 is axially displaceable on a shaft 4 between a disengaged position and the engaged position with the ring gear 3 - or generally two different positions - but is coupled to the shaft 4 in a rotationally fixed manner. The shaft 4 is driven by an electric machine or an electric drive motor 5 as a starter motor.

An axial advance movement of the starter pinion 2 takes place by means of the magnetic switch or starter relay 6, which is designed as an electromagnetic actuator and has an axially displaceable magnet armature 7 in a housing or relay housing 20, with the magnet armature 7 kinematically via a fork or engagement lever 8 the starter pinion 2 is coupled. The armature 6 has only indicated windings 18, 19, which can be energized via a power line 9, whereupon the armature 7 is adjusted against the force of a spring element 12 acting on it and the engagement lever 8 transmits the actuating movement to the starter pinion 2.

When the magnet switch 6 is switched off, the magnet armature 7 is moved into the starting position by the force of the spring element 12, and accordingly the engagement lever 8 also moves into a set-back position, which allows the starter pinion 2 to move back from the engaged position to the disengaged position.

The actuating movement of the armature 7 of the magnetic switch 6 is also used to switch the electric drive motor 5 on or off. The electric drive motor 5 is energized via a power line 10 in which a switch 11 is located, which is integrated in the housing of the magnetic switch 6.

The switch 11 has a contact bridge or switching bridge 13 and a switching axis 14, which is arranged coaxially to the magnet armature 7 and is axially displaceable in the housing. In addition, the switch 11 is supported on the housing 20 via a spring element 15. The spring element 15 is located on the switch 11 on the side facing away from the armature 7. The switching bridge 13 consists of an electrically conductive material in order to enable a current to flow in the contact position.

When the switch is closed, the switching bridge 13 is in contact with two contact elements 16 in the circuit of the drive motor 5, the contact elements, as will be seen later, generally being designed as connecting bolts. When the magnet switch 6 is actuated, the magnet armature 7 is adjusted, the adjusting movement of the magnet armature being transmitted via the switching axis 14 to the switching bridge 13 against the force of the spring element 15, whereby the switching bridge 13 is moved from the out of contact position into the contact position in which a Contact with the two contact elements 16 is made. The circuit is then closed and the drive motor 5 is started. As soon as the starter relay 6 is switched off, the armature 7 moves into the starting position, whereby the switch 11 is opened again by the force of the spring element 15. The current path with the power line 10, the contact elements 16, the contact bridge 13 and the electric drive motor 5 is also referred to as the main current path.

In Figure 2 an inventive magnetic switch 6 is shown in a preferred embodiment in a sectional view. The magnetic switch 6 can be the in Figure 1 act only roughly schematically shown magnetic switch.

As can be seen, the magnetic switch 6 in the housing 20 has windings 18 and 19 which can be energized and which generate a magnetic field which moves the magnet armature 7 axially. For example, the winding 18 can be a pull-in winding and the winding 19 can be a holding winding. The switching axis 14 is mounted axially displaceably in the housing 20 and is acted upon by force by the spring element 15 into the non-contact position of the movable part of the switch 11. The contact elements 16 - designed as connecting bolts - which are located in the main current path are also integrated or arranged in the housing 20, in particular a housing cover 21 as part of the housing 20.

One of the two connecting bolts 16 is divided into two parts 16.1 and 16.2, which are spatially separated from one another. Geometrically between these two parts 16.1 and 16.2, an NTC resistance element 30 is now arranged, which is electrically interconnected in this way, clamped between these two parts 16.1 and 16.2. For this purpose, the two parts 16.1 and 16.2 can, for example, be threaded in the housing 20 or the housing cover 21 be screwed. The housing cover 21 consists in particular of an electrically insulating material.

The NTC resistance element 30, which can in particular be a flat or plate-shaped element, lies flat against the corresponding ends or contact areas of the parts 16.1 and 16.2. In this way, the NTC resistance element 30 is provided in the main current path and can limit voltage drops. In addition, simple and safe assembly is also achieved.

In Figure 3 a magnetic switch 6 'according to the invention is shown in a further preferred embodiment in a sectional view. The magnetic switch 6 'basically corresponds to the magnetic switch 6 according to FIG Figure 2 so that reference can also be made to the explanations there.

In contrast to the embodiment according to Figure 2 However, the resistance element 30 is now designed, for example, in the form of a pin and arranged in an elongated direction, so that a bracing of the NTC resistance element is achieved through corresponding formations or blind holes in the ends of the parts 16.1 and 16.2. This also allows simple and safe assembly.

In Figure 4 a magnetic switch 6 "according to the invention is shown in a further preferred embodiment in a sectional view. The magnetic switch 6" basically corresponds to the magnetic switch 6 according to FIG Figure 2 so that reference can also be made to the explanations there.

In contrast to the embodiment according to Figure 2 however, the resistance element 30 is not arranged geometrically between the two parts 16.1 and 16.2 here. Rather, it is arranged, so to speak, as an extension of the switching axis 14 and thereby (indirectly) clamped between the spring element 15 and the housing cover 21. Two conductors or busbars 31 and 32 are provided, between which the NTC resistor element is geometrically arranged and which are each (electrically) connected to one of the two parts 16.1 and 16.2.

In this way, not only is simple and safe assembly achieved, but when the magnetic switch 6 ″ is actuated, the electrical contact between the conductors 31 and 32 and the NTC resistance element 30 is improved due to the spring force then acting.

In addition, an insulation element 35 can be arranged between the line 32, which here serves as a feed line for the NTC resistance element 30, and the spring element. This can prevent the spring element 15 or other components in contact with it from being subjected to tension.

Claims (8)

Magnetic switch (6, 6 ', 6 "), in particular starter relay, for a starting device (1) of an internal combustion engine (100), which has a connecting bolt (16) for a main current path of the starting device (1), and wherein an NTC Resistance element (30) is introduced,
wherein the NTC resistance element (30) is arranged in a housing (20) of the magnetic switch and is electrically connected between two parts (16.1, 16.2) of the connecting bolt (16). Magnetic switch (6, 6 ', 6 ") according to Claim 1, the NTC resistance element (30) being arranged in a housing cover (21) of the housing. Magnetic switch (6, 6 ') according to Claim 1 or 2, the NTC resistance element (30) being arranged geometrically between the two parts (16.1, 16.2) of the connecting bolt. Magnetic switch (6, 6 ', 6') according to Claim 3, the NTC resistance element (30) being mechanically braced and / or clamped between the two parts of the connecting bolt (16.1, 16.2). Magnetic switch (6 ") according to Claim 1 or 2, the NTC resistance element (30) resting at least indirectly on a spring element (15) which can be acted upon by a force by means of a magnet armature (7). Magnetic switch (6 ") according to Claim 5, with an insulation element (35) which is arranged between the NTC resistance element or a supply line (32) and the spring element (15). Magnetic switch (6, 6 ', 6 ") according to one of the preceding claims, with a further connecting bolt (16) for the main current path, an energizable winding (18, 19), a magnet armature (7) and a contact bridge (13), wherein the Magnetic switch is set up to move the armature (7) by energizing the winding (18, 19) and to contact the two connecting bolts (16) via the contact bridge (13) in order to electrically close the main current path. Starting device (1), in particular starter, for an internal combustion engine (100) of a motor vehicle, with an electrical machine (5) which is set up to start the internal combustion engine, with a magnetic switch (6, 6 ', 6 ") according to one of the preceding claims , and with a starter pinion (2) which can be rotated by means of the electrical machine (5), the starter pinion (2) being adjustable between two different positions by means of the magnetic switch (6, 6 ', 6 "), and the connecting bolt ( 16) of the magnetic switch is in the main current path of the starting device (1).

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