EP1883751A2

EP1883751A2 - Starting device for internal combustion engines in motor vehicles

Info

Publication number: EP1883751A2
Application number: EP06755069A
Authority: EP
Inventors: Karl-Otto Schmidt; Sven Hartmann; Klaus Heyers; Thomas Botzenhard; Walter Gerschwitz; Birgit Kuettner; Steffi Grellscheid; Apostolos Tsakiris
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-05-09
Filing date: 2006-05-08
Publication date: 2008-02-06
Also published as: CN101258322A; WO2006120180A3; US20090020091A1; BRPI0608793A2; WO2006120180A2; DE102005021227A1; JP2009500550A

Abstract

The invention relates to a starter device (10) for internal combustion engines (15) in motor vehicles with a controller (19), a starter relay (12), a starter pinion (13) and a starter motor (11), whereby on each start/stop process in the stop phase (first step) the starter relay engages the starter pinion in the toothed ring (14) of the engine and in the start phase (second step) the engine is turned over by the starter motor. According to the invention, the starter pinion (13) may be engaged as quietly as possible for a subsequent starting process on switching off the engine (10) and held in position until starting, whereby, in the first step of the starting process, the armature (28) of the starter relay (12) is withdrawn with reduced force to a position with open switch contact (18) and held there until the start of the second step, whereupon the armature (28) closes the switch contact (18) of the starter motor with full force.

Description

Starting device for internal combustion engines in motor vehicles

The invention relates to a starting device for internal combustion engines in motor vehicles according to the preamble of claim 1 with a starter relay according to the preamble of claim 5.

State of the art

Internal combustion engines of motor vehicles are usually started via a starter relay of a starter motor, the starter relay first spurs a pinion of the starter motor in a ring gear of the engine and finally connects the starter motor with the accumulator battery of the vehicle for cranking the engine with a switching contact. It is also known to equip motor vehicles with a so-called start-stop system. This ensures that at a longer stop, for example, at red traffic light phase, the internal combustion engine is automatically switched off. When driving on, an automatic restart of the internal combustion engine to continue the journey. The detection of the stop state, for example, by detecting the speed of the drive wheels and possibly one Selector lever position. The recognition of the start state can be done for example by pressing an accelerator pedal.

The automatic start-stop system offers the advantage of saving fuel and reducing fuel consumption

Environmental impact during the stop state. Unfavorable, however, is that before each new startup first a meshing of the pinion of the starter motor must be made in the ring gear of the flywheel of the engine. This is a greater mechanical stress on the pinion and the ring gear when meshing the pinion and when starting by a high spin is connected. This is especially the case with a so-called tooth-to-tooth position, because then the pinion is engaged with full rotational acceleration of the starter motor in the toothed ring of the machine. In addition, there is a time delay on each restart because the pinion must first mesh with the ring gear before the machine is actually started.

From EP 08 48 159 Al is also known to bring the starter pinion already at the beginning of a stop state of the machine in the Einspurstellung, then turn on the starter motor immediately with full force at the beginning of the start state. In this way, the time for cranking the internal combustion engine can be significantly reduced. In addition, the inrush current of the starter motor can be limited by electronic means. The engagement of the starter relay is carried out with relatively high dynamics to a in all operating conditions

To ensure functional safety. In particular, the relay winding is designed such that even at the upper limit temperature, a sufficiently high flux and pull-in force is ensured. In general, therefore, the starter relay is operated with too high energy to an increased noise emission leads. Thus, the early meshing of the pinion at a standstill of the machine leads to a clearly audible clicking noise as soon as the engagement relays and pulls the starter pinion axially against the ring gear or when engaging rotating against a tooth flank of the ring gear. This is irritating and unpleasant for the driver. However, the requirements of the starter relay with respect to a gentle, low-noise meshing on the one hand and the achievement of a high contact pressure to turn on the starter motor on the other hand are directed against each other and not sufficiently covered by the previously known starter relay. Although it is known to control the meshing of the starter pinion by means of an actuator and the starter motor starting independently of each other via two switching elements of a starting device. However, this leads to increased space and cost.

With the present solution is sought at a start-stop system, the starter relay such that at the beginning of a stop phase, the noise during Einspurvorgang greatly reduced and at the beginning of the start phase of the switching contact of the relay to turn on the starter motor with sufficient contact pressure is closed.

Advantages of the invention

The starting device according to the invention with the characterizing features of claim 1 has the advantage that the starter relay via a first path section with low dynamics and decreasing retraction force by the two-stage operation of the starter relay initially with the start of the stop phase for so-called pre-insertion of the starter pinion with open switching contact into the ring gear of the machine with a strongly reduced noise. Only at the beginning of the start phase is the switching contact of the starter relay in the last path section now closed with full dynamics and thus the starter motor is switched on. As a result, a separate control of the starter relay and the starter motor on space and costly semiconductor switch is also avoided. Another advantage is that a gentle engagement of the starter pinion wear on the mechanical parts can be greatly reduced.

The measures listed in the dependent claims expedient refinements and developments of the features specified in claim 1.

Thus, in a simple manner to achieve a reduced relay dynamics in the first stage of the excitation current of the relay winding of a control unit via a switching element from an initial value to the holding current, preferably stepped, reduced. The starter pinion now latches in the ring gear during the stop phase of the machine. With the start of the start phase, the excitation current of the starter relay in the second stage is then increased to a value required for the required contact pressure of the switching contact.

In an expedient development of the invention, the starter relay for stopping the armature after the meshing of the starter pinion in the stop phase is designed such that the magnetic force generated by the holding current in the first path portion of the armature greater than the force of the biased armature return spring, but less than the force another effective in the last path portion of the armature, preferably biased return spring. The biasing force of the further return spring is in expedient manner adjusted so that the anchor is able to overcome them only with increased energization of the starter relay for the last path section. In addition, it can be expedient with entrechendem extra effort that the starter motor in the first stage of a startup process for screwing the starter pinion in the ring gear of the machine via a further switching element of the control unit is directly controlled.

In order to track the starter pinion as gently and quietly as possible in the ring gear of the machine in the stop phase of the motor vehicle, the magnetic circuit of the starter relay is designed such that in a spring-loaded path range of the armature before the closing of the switching contact the change in the armature almost proportional to magnetic flux passes. For this purpose, the magnetic circuit is designed in such an advantageous manner that the armature of the starter relay in its rear path portion with a small radial air gap concentrically via a magnetic core of the

Relay intervenes. Conveniently, the armature is provided on its front, the magnetic core facing end side with an axially projecting collar which engages in the rear path portion of the armature via the front end of the magnetic core.

In order to keep the starter pinion in a reliable manner in the Einspurstellung and the switching contact of the starter relay in the open state during a stop phase of the vehicle, it is proposed in a further development of the invention that the armature of the starter relay at the end of the first path section on the further return spring can support. This results in a spring characteristic for the starter relay, which after the first path section of the armature upon reaching the prestressed further return spring has a stage which is overcome only with the full energization of the starter relay for the second path portion of the armature. Conveniently forms a contact restoring spring of the starter relay, the further return spring, which is actuated by a switching rod from the anchor.

Alternatively, it is also possible for a possible immediate start of the machine to advance the switching contact already in the first path portion of the armature until just before closing and to hold there by the biased further return spring during the stop phase. For this case, a contact pressure spring of the starter relay can be advantageously used as a further return spring, wherein already in the first stage, the switching rod carrying the switching contact is advanced to its support on the contact pressure spring.

drawing

The invention will be explained in more detail below by way of example with reference to FIGS. Show it:

Figure 1 is a schematic representation of the starting device for internal combustion engines in a general embodiment of the

Invention,

FIG. 2 shows a first exemplary embodiment

Longitudinal section through a starter relay of the starting device of Figure 1, Figure 3 shows different path-force characteristics of

Starter relay according to Figure 2,

FIG. 4 shows a time diagram with the essential variables for a start-stop sequence,

Figure 5 shows a schematic representation of the Starting device (a) at rest, (b) in Einspurzustand and (c) in the start state.

Figure 6 shows in a further embodiment, a modified starter relay in longitudinal section, Figure 7 shows the path-force characteristics of the starter relay according to Figure 6 and

Figure 8 shows a schematic representation of the starting device a) in the idle state b) in Einspurzustand and c) in the start state.

Description of the embodiments

FIG. 1 shows, in a schematic representation, a starter device according to the invention designated for 10 for internal combustion engines in motor vehicles. It essentially comprises a starter motor 11, a starter relay 12 and a starter pinion 13 for axial meshing in a ring gear 14 of an internal combustion engine 15 and a control unit 19. The starter relay 12 has a relay winding 16, a plunger 17 and a switching contact 18 for switching the main current for the starter motor 11. The control unit 19 supplies the relay winding 16 via a transistor Tri. Separately, the starter motor 11 is directly controlled by a further transistor Tr2 via a terminal K145 from the control unit 19. The two

Transistors Tri and Tr2 are on the input side via the terminal B + at the positive pole of the on-board voltage of the motor vehicle, not shown, or at the positive pole of a rechargeable battery of the vehicle. The transistors Tri and Tr2 are controlled separately at their control terminals via a microprocessor μP, which in turn can be controlled on the input side via a control bus 20 by an engine control unit 21. The engine control unit 21 can be activated via an ignition lock 22 and also detects various signals via an input bus 23 Driving condition of the motor vehicle, such as a clutch operation, a brake operation, the position of a gear selector lever, the engine and the wheel speed and the like. In addition, the microprocessor of the control unit 19 is connected to a temperature sensor T, which detects the temperature of the starting device 10.

The starting device 10 is activated during the driving operation of a vehicle by the engine control unit 21, in which the internal combustion engine is switched off from there at the beginning of a stop phase of the vehicle, for example by detecting the rotational speed at the front wheels of the vehicle. This is first triggered via the control bus 20 of the control unit 19 in a first stage Einspurvorgang the starter pinion 13 in the ring gear 14 of the machine 15 by a dosed excitation current is applied to the starter relay 12 via the transistor Tri. About the plunger 17, the starter pinion 13 is now advanced axially via an engagement lever 24 for meshing in the ring gear 14. In addition, the starter motor 11 is driven metered by the control unit 19 via the transistor Tr2 via the motor terminal K145, in order to turn the starter pinion 13 gently into the next tooth gap on the ring gear 14 in a tooth-on-tooth position. The starter pinion 13 now spurs completely silent in the ring gear 14 of the machine 15 and is held by the starter relay 12 in this position. The switching contact 18 remains in the open position. Only when, for example, by pressing the accelerator pedal, the driver's start request is detected by a corresponding signal of the engine control unit 21 to the control unit 19, the starter relay 12 is driven in a second stage for starting the engine 15 via the transistor Tri with increased current and thereby the switching contact 18 closed with full force. Thus, the starter motor 11 via the switching contact 18 of the starter relay 12 to the Terminal B + of the accumulator battery, not shown switched and the engine 15 is turned on immediately with full force.

FIG. 2 shows the first embodiment

Starter relay 12 of Figure 1 in its structural design in longitudinal section. The starter relay 12 has a relay winding 16 which is mounted on a support body 25 on a magnetic core 26. The relay winding 16 is inserted in a metallic housing 27, in the front, open end of the magnetic core 26 is received. At the bottom of the housing 27, an armature 28 of the relay is axially guided in an opening, which dips into the relay winding 16. In a central bore of the armature 28 of the plunger 17 is fixed, whose head-side end has a so-called paddle 29 for receiving the engaging lever 24 (Figure 1). In a through hole of the magnetic core 26, a shift rod 30 is guided by means of an insulating sleeve 31, wherein the front end of the shift rod with a distance a from the end of the plunger 17 is opposite. At the rear end of the shift rod 30, a contact bridge 18 a is received axially displaceable, which cooperates with two mating contacts 18 mounted in a switch cover 32. The contact bridge 18a is supported in its illustrated rest position via a Isolierstoffkappe 33 on the magnetic core 26 from. Contact bridge 18a and mating contacts 18b thus form the switching contact 18 of the contact relay, which is enclosed by the mounted on the end face of the housing 27 switch cover 32.

In an axial recess 34 of the armature 28, an armature return spring 35 is arranged, which is supported on the one hand at the bottom of the recess 34 and on the other hand on the magnetic core 26 of the relay. Furthermore, in a known manner in the switch cover 32, a contact return spring 36, which is supported on the one hand at the bottom of the switch cover 32 and on the other hand on a fixed to the right end of the shift rod 30 support plate 37. A contact pressure spring 38 is located in an axial recess 39 on the right side of the magnetic core 26. This spring 38 is supported on the one hand on the Isolierstoffkappe 33 on the contact bridge 18a and on the other hand on the insulating sleeve 31 on the shift rod 30 from. All three springs are biased, the more biased contact return spring 36 holds the contact bridge 18a against the bias of the contact pressure spring 38 is pressed into the rest position shown.

In order to be able to track the starter pinion 13 as quietly as possible into the ring gear 14 of the machine 15 at the beginning of a stop phase of the vehicle, the magnetic circuit of the starter relay 12 is designed in such a way that a path change is achieved in a middle path range of the armature path s, which is almost proportional to the change in the magnetic flux of the relay winding 16 runs. For this purpose, the armature 28 engages concentrically in its last path range s _o with small radial air gap over the magnetic core 26, in which the armature 28 is provided on its front, the magnetic core 26 facing end face with an axially projecting collar 41, which over the last Wegbereich s _{o of} the armature 28 is inserted into a recess 42 mounted on the circumference of the magnetic core 26, which is opposite to the collar 41 of the armature 28.

Figure 3 shows a more detailed explanation of the operation of different characteristics of the starter relay 12, wherein on the way s of the armature 28 on the one hand, the spring characteristic of the starter relay 12 as restoring force Pr and on the other hand, the force characteristics of the starter relay at different magnetic fluxes HO to H3 are shown. The Restoring force Pr is directed against the magnetic force of the relay.

Starting from the idle state of the armature 28 according to FIG. 2, first the pretension of the armature return spring 35 has to be overcome. By an axial advance of the armature 28 while only the armature return spring 35 is first compressed to position Sl by about 6mm, the spring force initially low and linear increases. In this position now engages the plunger 17 on the engagement lever 24 (Figure 1) and now spurting with some friction, the starter pinion 13 so far that it is able to einzuspuren in the ring gear 14 of the internal combustion engine 15. The armature 28 of the starter relay 12 moves to position S2. In this position, the anchor has the distance a between the

Tappet 17 and the shift rod 28 overcome and now presses on the shift rod 30 against the biased contact return spring 36, which forms a further return spring for the armature 28. Another anchor movement can only take place again, although the bias of the

Contact return spring 36 is achieved with the force Pl. With a steeper increase in force, the contact bridge 18a is then advanced by about 2 mm from the position S2 to the mating contacts 18b, thereby further tensioning the contact return spring 36. In position S3 now closes the switch contact 18 to turn on the starter motor 11. Thereafter, until the stop of the armature 28 on the magnetic core 26, the contact pressure spring 38 for the so-called burnup reserve of the switching contact 18 with the force P2 stretched further.

The four force characteristics of the magnetic flux of the armature on the armature stroke s are almost parallel to each other, the characteristic of the largest flooding H3 by a corresponding design of the relay winding 16 and is selected by a corresponding current through the transistor Tri of the control unit 19 so that it is well above the entire armature stroke s above the spring characteristic Pr of the relay. Due to the design of the starter relay 12 with the over the Rezess 42 of the magnetic core 25 cross collar 41 of the armature 28 is achieved in a middle path range A, which is approximately between the positions Sl and S2, a nearly horizontal course of the curves HO to H3. This makes it possible, in this path range of the armature for the magnetic flux ΔH almost proportional

Path change ΔS of the armature 28 to achieve. As a result, the magnetic flux can be reduced to the characteristic curve Ho with the appropriate dosage of the exciting current in the first stage of the so-called pre-tracking, so that the starter pinion 13 in the first path section SaI of the armature 28 is meshed with minimal noise into the ring gear 14 up to the position S2. By the prestressed contact return spring 38 is also ensured that the armature 28 is held during a stop phase of the vehicle with open switch contact 18 in the position S2. Only with the appearance of a start signal, the flow of the relay is now raised to the characteristic H3 via the control unit 19 and the switching contact 18 is then at the beginning of the second stage on the second path section Sa2 of the armature 28 with high dynamics and full power to turn on the starter motor 11 closed.

FIG. 4 shows the various signal curves of the starting device according to the invention during a stop and start phase. It is on the upper time axis ta the

Engine speed n of the internal combustion engine shown, including on the time axis tb an engagement signal Se for pre-tracking the starter pinion, including on the time axis tc is a start signal Sst and on the time axis td, the current waveform Ir in the relay winding of the starter relay, underneath, on the time axis te, a drive-in signal Sd for the starter motor for screwing in the starter pinion into the ring gear is shown and on the lower time axis tf the profile of the motor current Im is shown on the starter motor.

The description of a stop and start phase will be explained in greater detail with reference to FIG. 4 in conjunction with FIGS. 1 to 3 and FIG. In this case, in Figure 5, the starting device in a schematic representation in their

Rest position according to a) shown in its Einspurstellung according to b) and in their starting position according to c).

If the vehicle is stopped during driving, for example, in front of a traffic light system at a red phase of the traffic light, the engine control unit 21 recognizes according to Figure 1 via a sensor, the standstill of the driven wheels of the vehicle. If, in addition, the clutch is actuated and the idling speed of the internal combustion engine nθ is detected, the engine control unit 21 switches off the internal combustion engine at time tθ (FIG. 4). The speed signal now drops, for example, within one second to the speed 0. When the engine is stopped by the engine control unit when reaching the stop speed n _st at time tl the stop phase of the machine 15 is detected and an engagement signal Se via the control bus 20 to the control unit 19 laid. At this time, according to Figure 5a), the starter relay 12 is still in the rest position and the starter pinion 13 is still on the engaging lever 24 with the ring gear 14 of the machine 15 disengaged. Immediately thereafter, at time t2, the transistor Tri is controlled by the microprocessor μP in such a way that the relay winding 16 is initially charged with a relatively high relay current Ir in order to move the armature mass against the restoring force of the pretensioned armature return spring 35 to set in motion. The course of the magnetic force Pm of the starter relay 12 shown in bold in FIG. 3 initially follows the flow characteristic curve H2. The starter pinion 13 is thereby advanced by the relay armature 28 after a free travel of the plunger 17 via the engaging lever 24 initially to the ring gear 14. At time t3, the relay current Ir is now lowered by the control unit 19 via the transistor Tri by one stage. As a result, the magnetic force Pm is reduced by dropping according to FIG. 3 to the flow-through characteristic Hl. However, since this magnetic force is still significantly higher than the restoring force Pr of the armature return spring 35, the armature 28 is retracted even further into the relay winding 16. At about the same time, the microprocessor μP of the transistor Tr2 of the control unit 19 is controlled so far conductive that now the starter motor 11 is supplied via the transistor Tr2 with low current Im. As a result, the starter pinion 13 is rotated gently and immediately axially via the engagement lever in the ring gear 14 axially eingespurt. At time t4, the relay current Ir is now lowered by one more stage.

Accordingly, the magnetic force Pm of the starter relay 12 drops from the flooding characteristic Hl to the flooding characteristic HO. With this magnetic force now the armature 28 is retracted to the position S2, where it is supported with the plunger 17 on the shift rod 30 which is loaded with the bias of the contact return spring 36. In this position, the starter relay 12 stops, as long as the stop phase of the internal combustion engine persists. FIG. 5b) shows the starting device in this so-called pre-insertion position. The switching contact 18 is still in the open state. The transistor Tr2 of the control unit 19 is now locked again and the starter motor 11 is de-energized again. If the traffic light system now switches back to a green phase, the driver merely has to actuate the accelerator pedal so that the engine control unit 21 then issues a start signal to the control unit 19 at the time t5. From the microprocessor, the transistor Tri is now fully conductive and controlled

Relay winding 16 of the starter relay 12 is now acted upon by the full excitation current Ir. As a result, the magnetic force Pm, according to FIG. 3, jumps from the throughflow characteristic curve HO to the characteristic curve H3, thereby clearly exceeding the restoring force Pr of the springs 35, 36 and 38 of FIG

Starter relay 12. The armature 28 is now retracted with full force to the stop on the magnetic core 26. Thus, in the second path section Sa2 (FIG. 3), the contact bridge 18a is pressed over the shift rod 30 onto the mating contacts 18b and finally the required contact pressure is generated via the contact pressure spring 38. Now, the starter motor 11 is placed on the positive potential of the accumulator battery, so that the starter motor 11 now with full force on the Einspurritzel 13, the engine 15 can rotate. In Figure 5c) is this so-called start phase of

Starting device shown, via the engaging lever 24, the Einspurritzel 13 is held spring-loaded in the Einspurstellung. At time t6, the relay current Ir can be lowered by the control unit 19 via the transistor Tri to the so-called holding current Ih, since this is sufficient to generate a lying above the spring characteristic Pr of the starter relay 12 magnetic force Pm. As soon as the internal combustion engine goes into self-running, the speed increases sharply by the operation of the accelerator pedal. When idling speed n ₀ is reached, the transistor Tri is thus blocked at time t7 via control unit 19. The relay is de-energized and by the restoring forces of the springs 35, 36 and 38, the armature 28 is now pushed back into the rest position. In this case, the switching contact 18 is opened and the Einspurritzel 13 off the sprocket 14 of the internal combustion engine 15 ausgepurt. The current of the starter motor 11 is interrupted thereby stopping the starter motor. The starting device thus returns to its rest position according to FIG. 5a) and remains there until the internal combustion engine 15 is stopped again for a stop phase and then the previously described meshing and starting operation is run through.

In the first embodiment of Figure 2 to 5, the contact return spring 36 of the starter relay 12 as a further

Return spring for the armature 38 is used, which holds the starter pinion 13 in the Einspurstellung in the stop phase, wherein the switching contact 18 of the starter relay 12 remains in its rest position in the open position due to the biasing force of the contact return spring 36. Only at the beginning of the start phase, the switching contact 18 is closed at full force in the second stage of the starter relay 12 by the current in the relay winding 16 is increased to a value required for the required contact pressure of the switching contact 18.

Figure 6 shows in a further embodiment, a starter relay 12 in cross-section, the constructive structure substantially corresponds to the starter relay 12 of Figure 2 and whose parts are provided with the same reference numerals. Notwithstanding the first embodiment, the starter relay of Figure 6, a smaller distance a 'between the plunger 17 of the armature 28 and the shift rod 30 of the switching contact 18 is provided. In addition, there the contact pressure spring 38 is supported on an annular disc 40 which rests in the idle state of the relay at the bottom of the recess 39 of the magnetic core 26 and which is received on the shift rod 30 axially displaceable. The Isolierstoffhülse 31 of the shift rod 30 terminates at a distance b below the annular disc 40. Due to these structural changes also a change in the spring restoring force of the starter relay 12 on the armature stroke s.

The operation of the relay according to Figure 6 will now be explained in more detail with reference to Figures 7 and 8. Figure 7 shows on the way s of the armature 28 on the one hand, the spring characteristic of the starter relay 12 as restoring force Pr and on the other hand, the force characteristics of the starter relay at different magnetic fluxes HO to H3. Figure 8 shows similar to Figure 5, the starting device in a schematic

Representation in the rest position according to a), in the Einspurstellung according to b) and in the starting position according to c).

Starting from the idle state of the armature 28 according to Figure 6 and Figure 8 a), the bias of the first

Armature return spring 35 are overcome. By an axial advance of the armature then the armature return spring 35 is compressed to position Sl by about 4mm, the spring force initially low and linear increases. In this position, according to Figure 1 via the engaging lever 24, the starter pinion 13 vorgespurt and light energization of the starter motor 11, it is meshed with the ring gear 14 of the engine 15. In this case, the armature 28 of the starter relay 12 initially moves to position Sl 'in Figure 7, where now the plunger 17 of the armature 28 strikes the shift rod 30, which is held with the biasing force of the contact return spring 36 in this position with a force Pl. Up to this position, the exciter current is now gradually reduced by reducing the flooding from the characteristic H2 to HO. The magnetic force Pm generated by the flooding HO is in contrast to the first embodiment greater than the biasing force of the contact return spring 36, so that now the armature is moved beyond the position Sl 'out to the position S2. In this position now pushes the insulating sleeve 31 of the shift rod 30 against the annular disc 40, on which the prestressed contact pressure spring 38 is supported. By the stroke of the armature 28 from the position Sl 'to position S2 is further the contact bridge 18a of the shift rod 30 to a position just before touching the

Mating contacts 18b advanced. Due to the flooding HO, the magnetic force is now so low that the armature 28 is held in this position during the entire stop phase of the vehicle.

A further armature movement can only take place again if the pretensioning force of the contact pressure spring 38 with the value P2 is also overcome. This happens at the beginning of the start phase, when the relay flooded to the characteristic H3 by the full current supply of the relay winding

16 is raised. As a result, the contact bridge 18a is finally advanced from the position S2 with a steeper force increase up to the mating contacts 18b, and finally also until the stop of the armature 28 on the magnetic core 26, the contact pressure spring 38 is further tensioned for the required contact pressure.

In this embodiment, the contact pressure spring 38 for the armature 28 forms a further return spring with which the starting device is held in the Einspurstellung the starter pinion with the switch contact 18 open. Since in this embodiment, the switching contact 18 is already raised during the stop phase until shortly before closing, resulting in the start-up phase almost instantaneous turning of the machine by an immediate closing of the

Switching contact 38 for full energization of the starter motor 11th

The invention is not limited to the described embodiments, since the Start device in many details can be modified. It is thus possible, for example, to control the starter relay 12 and / or the starter motor 11 in a clocked manner during the so-called pre-insertion as well as in the holding phase. In this case, the transistors Tri and Tr2 are preferably controlled with a changed duty cycle via the microprocessor μP in order to limit the switching losses. In addition, in this way, via the temperature sensor T of the control unit 19, the current of the starter relay 12 and of the starter motor 11 can be temperature-dependently optimized to the respectively required force. Furthermore, it is possible, with a dashed lines shown in Figure 4, extended starting signal Sd to drive the starter motor 11 longer to rotate after screwing the starter pinion 13 in the ring gear 14 of the engine 15 this to a compression position, which also on the time axis ta the engine speed n is indicated by dashed lines. Thereby, the starting operation of the internal combustion engine 15 can be further accelerated. Essential to the invention is the dynamic behavior of the starter relay 12 by the control of the relay current through the control unit 19 in combination with a suitable spring design of the starter relay 12 to divide the feed and switching operation of the relay in two stages such that in the first stage a linear , Low-noise engagement of the starter pinion 13 is ensured for a soft Voreinspuren in the ring gear 14 of the internal combustion engine 15. The design of the magnetic circuit takes place in such a way that the required for the flooding of the relay current remains as small as possible. In addition, in the holding position of the relay for the time of Voreinspurens the remaining air gap of the magnetic circuit - and thus the contact distance of the switching bridge 18a to the mating contacts 18b- to minimize. Only in the second stage, the magnetic flux of the Relay increased such that the Kontaktrückstell- and Kontaktandruckfeder 36 and 38 are bridged and the switch contact 18 is closed to switch the main current for the starter motor 11.

For the activated with the beginning of the second stage of the starter relay 12 further return spring 38 Although the contact restoring spring or the contact pressure spring for the switching contact 18 of the relay is used in the embodiments. However, the further return spring can just as well be arranged as a separate return spring, for example concentric to the armature return spring so that it is acted upon by the armature 28 with a correspondingly large magnetic force only at the beginning of the second stage. The different springs of the relay are in each case

Trap to match such that a stepped spring characteristic Pr shown in Figure 3 and 7, respectively. It is also possible to realize a more or less pronounced gradation of the spring characteristic at the beginning of the second stage of the starter relay 12.

In a further modification of the starting device, it is also possible to turn on the relay winding 16 of the starter relay 12 in the second stage of a startup at time t5 in Figure 4 via a control relay SH -in the same way as for a cold start of the engine directly from the engine control unit 21 this is indicated by dashed lines in Figure 1.

Claims

claims

1. Starting device (10) for motor vehicles with a control unit (19) and with a starter relay (12) for meshing a starter pinion (13) in a ring gear (14) of an internal combustion engine (15), and with a starter pinion driving starter motor (11) in which the starter relay has a relay winding (16) and a Hauptström the starter motor switching switching contact (18), in each of which during a start-stop process during the stop phase in a first stage (SaI) the starter pinion meshes with the ring gear and during the start-up phase in a second stage (Sa2) the internal combustion engine is turned off by the starter motor, characterized in that in the first stage (SaI) with the pre-tracking of the starter pinion (13) of the armature (28) of the starter relay (12) reduced force up to a position (S2) with still open switching contact (18) advanced and held there until the beginning of the second stage (Sa2) of the switch contact (18) with full Kr aft closes.

2. Starting device according to claim 1, characterized in that the control unit (19) in the first stage (SaI) the

Current (Ir) in the relay winding (16) via a switching element (Tri) from an initial value to a holding current, preferably stepped, and reduced in the second stage (Sa2) the current (Ir) to one for the required contact pressure of the switching contact ( 18) required value increased.

3. Starting device according to claim 2, characterized in that the by the holding current in the first path portion (SaI) of the armature (28) generated magnetic force (Pm) larger is than the force of the biased armature return spring (35), but less than the force of another, in the last path section (Sa2) effective, preferably biased return spring (36, 38).

4. Starting device according to claim 3, characterized in that the biasing force of the further return spring (36, 38) only with increased energization of the starter relay (12) for the last path portion (Sa2) of the armature (28) is overcome.

5. starter relay for a starting device according to claim 1, characterized in that the magnetic circuit of the starter relay (12) in a spring-loaded path range (A) of the armature (28) before the closing of the switching contact

(18) is designed for a magnetic flux (ΔH) almost proportional path change (ΔS) of the armature (28).

6. starter relay according to claim 5, characterized in that the armature (28) concentrically in its rear path portion (Sa2) with a small radial air gap via a magnetic core (26) of the starter relay (12) engages.

7. starter relay according to claim 6, characterized in that the armature (28) on its the magnetic core (26) facing the end face with an axially projecting collar (41) is provided in the rear path section (Sa2) of the armature (28) over the front end of the magnetic core (26) engages.

8. starter relay for a starting device according to claim 3, characterized in that the armature (28) of the starter relay (12) at the end of the first stage on the further return spring (38) is supported.

9. starter relay according to claim 8, characterized in that a contact return spring (36) of the starter relay (12) forms the further return spring which is to be actuated via a switching rod (30) from the armature (28).

10. Starter relay according to claim 8 or 9, characterized in that the switching contact (18) already in the first path section (SaI) of the armature (28) to advance shortly before closing and there by the biased, further return spring (36) during the stop Phase is to hold.

11. Starter relay according to claim 10, characterized in that a contact pressure spring (36) of the starter relay (12) forms the further return spring.

12. A starter relay according to claim 11, characterized in that already in the first stage (SaI) the switching contact (18) carrying the shift rod (30) is advanceable up to its support on the contact pressure spring (36).