EP1493919A2 - Starter for an internal combustion engine - Google Patents

Abstract

The drive unit includes components (42, 50) sliding axially relative to each other and coupled together. When the starter pinion is braked between the gear ring and the frictional forces acting on it, an engagement spring is further preloaded. Because the engagement unit mass is reduced, the pinion is very rapidly accelerated into mesh with the ring gear on tooth/gap alignment.

Description

The invention relates to a starter for an internal combustion engine according to Preamble of claim 1.

State of the art

As electric starter for cranking internal combustion engines often used so-called Schraubtrieb starter. Such a Screwdriver starter has an electric starter motor, whose drive shaft with a displaceable in the direction of its longitudinal axis Output shaft is in operative connection. The drive shaft is at a remote end of the starter motor with a coarse thread provided on the rotatable and displaceable Mitnehmerschaft the output shaft is arranged. This entrainment of the Output shaft is over a freewheel with a pinion having Shank connected. By switching on the starter motor is the Output shaft with the Mitnehmerschaft, the freewheel and the pinion shaft so vorgespurt that the pinion into a gear wheel of the internal combustion engine meshes. This gear is normally locked connected to a crankshaft of the internal combustion engine and is typical formed as external teeth on a flywheel.

A working according to the so-called brake screwdriving principle Starter is known from DE 100 16 706 A1. This well-known starter motor has a pole tube, which when energized the motor performs a pivoting movement about the motor axis. With this Pivoting movement of the pole tube is a braking mechanism in Gear set, which has a braking torque on the driving force of the Output shaft exerts. This braking torque causes the Mitnehmerschaft over the coarse thread of the drive shaft of the engine is driven so that the pinion of the starter in the sprocket the internal combustion engine einspurt.

A generic Schraubtrieb starter for cranking a Internal combustion engine is known from WO 03/008798 A1. In this known starter is a feed of an output shaft for Traces of a pinion in the ring gear of an internal combustion engine by means of a pole tube arranged on the stator of the starter motor causes, when energized the starter motor pivotal movement around the motor axle experiences. There are facilities provided which the pivoting movement of the pole tube directly into a Convert axial movement acting on the output shaft.

Advantages of the invention

A starter for an internal combustion engine according to the present invention has a starter motor and a drivable by this Drive shaft and one in operative connection with the drive shaft, displaceable in the direction of its longitudinal axis output shaft on, which with a pinion shaft with a in a sprocket the Internal combustion engine engageable pinion is coupled. A feed the output shaft for meshing the pinion in the sprocket can in particular by means of a provided on the starter of the starter motor Elements take place when energizing the starter motor undergoes a pivoting movement about the motor axis. These Pivoting movement is by means of a mounted on the drive shaft, around this rotatable and axially in the feed direction against a spring force supported disc in a force acting on the pinion shaft axial movement implemented.

Alternatively, however, there are other ways to apply the axial feed force on the output shaft. According to the invention is provided that the driver unit at least out two radially in the direction of rotation coupled to each other and axially against each other consists of sliding elements.

Due to the two-part design of the driver unit, the be reduced to accelerating mass when starting. If the starter pinion due to its inertia and frictional forces between Sprocket and starter pinion faces is braked, Nevertheless, the Einspurfeder can be further biased. By The lower mass of the track unit may end up with the pinion Einspurbewegung very quickly at a tooth gap position in the Sprocket to be accelerated.

The spring force can act in particular on a drive plate, coupled with a threaded sleeve and axially displaceable on this is. The threaded sleeve is preferably on the drive shaft stored and with this by means of a steep thread form-fitting coupled. Preferably, the threaded sleeve and the driver by means of a positive connection in the direction of rotation with each other coupled. This positive connection can, for example, in the form an external toothing on the threaded sleeve and a corresponding thereto Internal teeth on the drive plate exist.

The external teeth of the threaded sleeve and the internal teeth the drive plate can be used in particular as a degree gear teeth be formed, for example. As triangular gears or the like.

The threaded sleeve can in an advantageous embodiment of a lighter material than steel, for example. Plastic or a composite material be made. In this way their can be accelerated Mass be reduced significantly.

Preferably, the pinion shaft via the threaded sleeve is indirectly supported, so that the pinion shaft a defined storage and thus has a perfect concentricity.

Further advantageous embodiments of the invention will become apparent the rest, mentioned in the dependent claims features.

drawings

Figur 1

einen schematischen Längsschnitt eines erfindungsgemäßen Starters in einer ersten Variante,

Figur 2

einen schematischen Halbschnitt eines Teils des Starters gemäß Figur 1,

Figur 3

einen perspektivischen Teilschnitt des Starters in einer modifizierten Variante,

Figur 4

eine Mitnehmerscheibe sowie eine damit koppelbare Gewindehülse des Starters,

Figur 5

die Mitnehmerscheibe gemäß Figur 4 in einer gedrehten Ansicht und

Figur 6

die Gewindehülse gemäß Figur 4 in vergrößerter Perspektivdarstellung.

The invention will be explained in more detail in preferred embodiments with reference to the accompanying drawings. Showing:

FIG. 1

3 shows a schematic longitudinal section of a starter according to the invention in a first variant,

FIG. 2

1 is a schematic half section of a part of the starter according to FIG. 1,

FIG. 3

a perspective partial section of the starter in a modified variant,

FIG. 4

a drive plate and a thus coupled threaded sleeve of the starter,

FIG. 5

the drive plate according to Figure 4 in a rotated view and

FIG. 6

the threaded sleeve according to Figure 4 in an enlarged perspective view.

Description of the embodiments

The illustrated in Figure 1 as a longitudinal section starter 10 has a two-part housing, wherein a first housing part 12 a Starter motor 11 surrounds and a second housing part 14, the drive bearing (not shown) of the starter. The starter motor 11 includes in known manner a stator 16 and a rotatable therein mounted rotor 18. The stator 16 has a pole tube 20 and therein arranged, designed as permanent magnets stator poles 22. The pole tube 20 forms the magnetic return for the stator poles 22, which are arranged concentrically around the rotor 18 around. The rotor 18 has a motor shaft 24 which is provided with a laminated core rotatably connected. In not shown grooves of the laminated core one or more rotor windings are introduced.

The emerging from the starter motor 11 motor shaft 24 is connected to a Transmission, preferably a planetary gear 26 coupled. The motor shaft 24 drives a sun gear 28, and the sun gear 28 meshes with planetary gears 30 and 32, which in turn roll off a ring gear 34. The ring gear 34 is connected to an intermediate bearing 36 connected. The planet gears 30 and 32 are from a Planet carrier 38 held. The intermediate storage 36 is stationary and rotatably disposed in the second housing part 14 of the starter 10. Of the Planet carrier 38 is rotationally fixed, e.g. integral with a drive shaft 40 connected.

On the drive shaft 40, a threaded sleeve 42 is set. The drive shaft 40 and the coaxial with this arranged threaded sleeve 42 are coupled via a coarse thread 44 with each other. That is, at one Inner lateral surface of the threaded sleeve 42 and at a portion an outer circumferential surface of the drive shaft 40 is one each Steep thread toothing applied. This the drive shaft 40th and the threaded sleeve 42 connecting coarse thread 44th represents a so-called Einspurgetriebe. The threaded sleeve 42nd has an outer toothing at a portion of its outer periphery 46, in which an internal toothing 48 of a drive plate 50 engages. The drive plate 50 goes into an outer ring 52 of a freewheel 54 via.

The outer ring 52 of the freewheel 54 drives via not shown Clamping an inner ring 56, which with a pinion shaft 58th connected is. At his from the second housing part 14 of the starter 10 pointed end is the pinion shaft 58 with a pinion 60 provided with spur toothing. The pinion shaft 58 experiences upon rotation of the motor shaft 24 by the helical thread 44 running Einspurgetriebe between the drive shaft 40 and the output shaft 43 a feed, so that the pinion 60 in a sprocket 62 einspurt an internal combustion engine, not shown. Of the Einspurvorgang and the Ausspurvorgang will be in the following described in more detail.

The drive shaft 40 is within the threaded sleeve 42, drive plate 50 with freewheel 54 and pinion shaft 58 formed output shaft 43 rotatably mounted (not shown). Furthermore, it is the output shaft 43 preferably in the second housing part 14th via at least one bearing (not shown) about its longitudinal axis rotatably mounted.

The pole tube 20 of the starter motor 11 is about the axis of rotation of the motor shaft 24 pivotable at a certain angle (about 10 ° to 30 °) stored. On the pole tube 20 are one or more - for example three arms 64 extending into the second housing part 14, in which the transmission is for driving the output shaft 43, extend into it. Each arm 64 of the pole tube 20 is through a Recess 66 on the outer circumference of the second housing part 14th rotatably arranged intermediate bearing 36 out. Every recess 66 on the intermediate bearing 36 or on a brush holder 83 has two Stops 68 and 70 on which the pivoting movement of the pole tube Limit 20 around the motor axis. A recess 66 on Intermediate bearing 36 with its two stops 68 and 70 and a guided therein arm 64 of the pole tube 20 shows the perspective Representation of a section of the starter 10 in the figure 3.

As soon as the starter motor is energized, acts on the pole tube 20 due of prevailing between the rotor 18 and stator 16 electromagnetic Forces a torque, causing the pole tube 20 in a certain direction, e.g. clockwise around the motor axis is turned. It is a spring element not shown in the drawing provided, which this torque of the pole tube 20th counteracts. The spring element can eg. At the intermediate storage 36th be installed. The height of the torque acting on the pole tube 20 depends on the strength of the current flowing through the rotor winding Power off.

On the threaded sleeve 42 of the output shaft 43 is a substantially radially projecting disc 72 mounted so that they are around the Axle of the threaded sleeve 42 of the output shaft is rotatable. Against one axial displacement against the feed direction of the threaded sleeve 42, the disc 72 is secured. This is done, for example, by means of an on the threaded sleeve 42 patch retaining ring 74, on which the disc 72 is present. The retaining ring 74 is by means of a locking ring 76th against an axial displacement against the feed direction of the Output shaft 43 secured.

With a rotation of the pole tube 20 and the disc 72 is rotated and simultaneously displaced in the axial direction, as shown Figure 3 is explained in more detail.

On the freewheel 54 facing side of the disc 72 is a Support ring 78 placed on the threaded sleeve 42, of a on the outer ring 52 of the freewheel 54 supporting spring 80 against the Disk 72 is pressed. This spring is due to its function when meshing the pinion 60 in the ring gear 62 below designated as Einspurfeder 80. Between the disc 72 and the second housing part 14, a further spring 82 is inserted, which as the Einspurfeder 80 a pressure on the disc 72 and thus on the output shaft 43 against the feed direction of the output shaft 43 exercises. This second spring is hereinafter referred to as Ausspurfeder 82 indicates because they are out of the pinion 60 from the ring gear 62 supported. The aforementioned single track or Traction forces can also be used with other spring elements attached to others Positions in the starter 10 are arranged as shown in the figures, be applied. For example. can the spur of the 82 too between the pinion shaft 58 of the axially displaceable output shaft 43 and the pinion end of the axially fixed drive shaft 40th be used as in the alternative variant accordingly Figures 2 and 3 is shown.

Figure 2 illustrates in a semi-longitudinal section, the arrangement of central assembly for transmitting the rotational movement of the starter motor 11 on the pinion shaft 58 and the generation of the Traces of the pinion 60 in the ring gear 62 necessary feed movement. Clearly recognizable here is in particular the coarse thread 44 of the drive shaft 40, via which a rotary and feed movement on the threaded sleeve 42 is transferable. For this has the threaded sleeve 42 on its inner circumference with a coarse thread 44 of the drive shaft 40 corresponding coarse thread on. On the outer circumference is at the starter motor 11 facing Side of the threaded sleeve 42 an external toothing 46 is provided, with the corresponding internal teeth 48 of the drive plate 50 corresponds. Thus, threaded sleeve 42 and drive plate 50 independently from each other in the axial direction against each other be moved.

However, the teeth 46, 48 always ensure a positive fit Rotary connection for transmitting the necessary torque on the output shaft 43 and the pinion shaft 58. Further is arranged in the outer ring 52 of the drive plate 50 freewheel 54 recognizable, for a torque transmission in only one Direction ensures and the pinion shaft 58 in the opposite Turn the direction of rotation freely. This can ensure that an already running internal combustion engine does not cause damage of the starter 10 can lead, but that of the pinion shaft 58 freely rotate with still meshed in the ring gear 62 pinion 60 can. In the illustration of Figure 2 shown is also the axial Power transmission from the disc 72 via the Einspurfeder 80 on the drive plate 50 illustrates.

FIG. 3 shows a perspective partial sectional view of the assembly corresponding to Figure 2, in particular, the rotation the disc 72 by means of engaging in second recesses 84 Arms 64 is illustrated. A slimmer end section each Arms 64 has chamfers, which by sliding on the stops 86 and 88 of each second recess 84 for a axial feed of the disc 72 can provide in Einspurrichtung. With an axial feed of the disc 72 is on the Einspurfeder 80 exerted an axial force on the drive plate 50, the in turn on the freewheel 54 the pinion shaft 58 with the thereto End-mounted pinion 60 in Einspurrichtung, i. in the direction to the ring gear (not shown) of the internal combustion engine shifts.

In the variant of the insertion device shown in FIG the Ausspureder 82 disposed within the pinion shaft 58 and is supported between a stop disc 90 at the axial end of the Pinion 60 and a radial support collar 92 of the threaded sleeve 42nd from. The spring force of the Ausspurfeder 82 is thus the spring force of Einspurfeder the 80 opposite and ensures a trace of the Pinion 60, as soon as the axial force component through the axially displaced Disc 72 is eliminated. This is the case when the starter motor 11 is no longer energized, the pole tube 20 in its initial position turns back and the arms 64 again in one of the arrow directions Swing back.

The explained with reference to Figures 1 to 3 way to apply the axial feed force on the output shaft provides only one of several possible variants. This variant is thus not restrictive to understand. The axial force component can optionally also by means of a separately operable by the drive motor Actuator done, for example. By means of an electromagnet, the via suitable actuating arms causes a feed of the output shaft.

Reference to the figures 4 to 6, an exemplary embodiment of Threaded sleeve 42 and the engaged therewith drive plate 50 illustrates. Figure 4 illustrates in particular the axial Displacement of the provided with the external teeth 46 threaded sleeve 42 in the axial direction in the with the internal teeth 48th provided drive plate 50. The teeth are shown in the Embodiment designed as a straight toothing.

With reference to Figure 5, the design of the outer ring 52 of the drive plate 50 for receiving freewheel pawls or rollers (not shown) of the freewheel clarifies.

Figure 6 illustrates the design of the threaded sleeve 42, the at the the support collar 92 side facing away from the toothed outer circumference a recess 94 for receiving the locking ring 76 to the axial Fixing the retaining ring 74 and the disc 72 has. One to External teeth 46 directed stop surface 96 on the support collar 92nd at the same time forms an axial stop, the displaceability the threaded sleeve 42 is limited against the drive plate 50.

The drive plate 50 can in particular be extruded from a metal become. The threaded sleeve 42 may, for example. Metal or consist of a suitable composite material.

When energizing the starter motor 11, the disc 72 is in shifted axial direction, which also the pinion shaft 58 in the direction is moved to the ring gear 62. This axial movement of the pinion shaft 58 is determined by the inertia of the Einspureinheit and a sliding of the threaded sleeve 42 via the coarse thread 44 due the rotational movement of the motor shaft 24 is supported. Support takes place at the beginning of the Einspurvorgangs only in weak Extent.

During toe-in it can happen that the teeth of the Ritzel 60 not in the tooth flanks of the ring gear, but that the tooth tips touch and it by frictional forces initially does not come to a meshing. This will be a Equilibrium state reached between the effective Polrohrmoment and the counteracting moment due to the Spring force of the single lane of the 80. For smaller starters 10, like them especially for smaller internal combustion engines, the pole tube torque may be too weak to handle the Einspurfeder 80 further to compress and the Einspureinheit (output shaft 43) with full biasing force of the Einspurfeder 80 against To press the tooth flanks of the ring gear 62 and the pinion 60th at a tooth gap position with appropriate acceleration in to push the teeth of the ring gear 62.

The two-part driver according to the invention, consisting of threaded sleeve 42 and drive plate 50 allows it now in an advantageous Way to further compress the lane of the 80, when a tooth-on-tooth position of the pinion 60 on the Toothed ring 62 prevents complete meshing first. Due to the friction between the end faces of the pinion 60 and the Sprocket 62, the rotational movement of the starter pinion 60 first braked.

The already rotating starter motor 11 provides through the coarse thread for an axial displacement of the threaded sleeve 42 in a rectilinear Form fit axially within the drive plate 50, whereby at the same time the Einspurfeder 80 are biased further can. If a tooth gap is subsequently found, then the Einspurfeder 80 the starter pinion 60 in the ring gear 62 into it. Due to the additional frictional torque between the tooth flanks within the possible bolting path the entire pick-up unit by the rotating starter motor 11 via the coarse thread 44 screwed into the ring gear 62, even if already the maximum Displacement of the disc 72 and thus the threaded sleeve 42 against the drive plate 50 is reached.

At the end of the Schraubwegs relaxed the Einspurfeder 80 and the entire pick-up unit is fully inserted into the stop Tooth gap of the ring gear 62 pressed. Due to that due to Braking torque of the engine braked starter pinion 60 and the sliding under the drive plate 50 through threaded sleeve 42 is on the coarse thread 44, a reverse rotation of the Pinion shaft 58 allows, which can also lead to an unfavorable tooth-on-tooth position can be canceled, to enable a successful meshing process.

The division according to the invention of the Einspureinheit allows a reduction in the acceleration of the starter motor 11 to be accelerated Mass, allowing the pinion 60 as possible when cranking quickly accelerated to the next tooth gap of the ring gear 62 is turned on and the internal combustion engine successfully can be. A sufficiently high biasing force of the Einspurfeder 80 and a small mass to be accelerated can by a Separation and axial displacement with simultaneous radial Positive connection of Einspureinheit in a threaded sleeve and a drive plate be achieved. In addition, with this constructive Embodiment introduced when energizing the starter motor 11 Rotational movement of the pole tube 20 can be used to at a Tooth-on-tooth position to further bias the Einspurfeder 80.

By the separation of the inching unit according to the invention can the mass to be accelerated can be reduced. The each other sliding parts threaded sleeve 42 and drive plate 50th are in so-called. Free-launching starters inside the starter housing and are thus secured against ingress of dirt. If the starter motor 11 is already rotating, the starter pinion 60 but on Reason for its inertia and friction between sprocket and starter pinion faces is braked, can now the starter motor 11 via the coarse thread 44 of the drive shaft 40 and the threaded sleeve 42 move this axially further against the drive plate 50 and biasing the lashing spring 80 further therewith. The now lower Mass of the Einauge unit can at the end of the screw very accelerated quickly in toothed position in the ring gear 62 become.

By eliminating a Mitnehmerschafts the driver can be very be built flat and in an advantageous manner, for example, in one operation be pressed together with the internal toothing 48. The subsequent machining effort for final shaping is relatively low. A broaching process can be omitted, since the drive plate 50 has no coarse thread more, because this was displaced into the threaded sleeve 42.

The threaded sleeve 42 may depending on the strength requirements Steel, made of plastic or of a composite material become.

Claims (12)

Starter for an internal combustion engine, comprising a starter motor (11), a drive shaft (40) drivable therefrom and an output shaft (43), which is operatively connected to the drive shaft (40) and displaceable in the direction of its longitudinal axis, with a pinion shaft (58) coupled to a sprocket (62) of the internal combustion engine pinion (60) is coupled, wherein a feed of the output shaft (43) for meshing the pinion (60) in the ring gear (62) in particular by means of a feed on the output shaft (43) mounted , To this rotatable and axially supported in the feed direction against a spring force washer (72), the feed in a on the pinion shaft (58) acting axial movement is implemented, wherein the spring force between a driver unit mounted on the drive shaft (40) and with this is positively coupled by means of a coarse thread (44), and the disc (72) acts, characterized in that the driver unit zumi ndest from two radially in the direction of rotation coupled to each other and axially against each other displaceable elements (42, 50). Starter according to claim 1, characterized in that the driver unit comprises a threaded sleeve (42) and a drive disc (50) couplable therewith. Starter according to claim 2, characterized in that the spring force between the disc (72) and the driver disc (50) acts, which is coupled to the threaded sleeve (42) radially positive fit and axially displaceable against them. Starter according to claim 2 or 3, characterized in that the threaded sleeve (42) mounted on the drive shaft (40) and with this by means of a coarse thread (44) is positively coupled. Starter according to one of claims 2 to 4, characterized in that the threaded sleeve (42) and the drive plate (50) are coupled together by means of a positive connection in the rotational direction. Starter according to claim 5, characterized in that the threaded sleeve (42) has an external toothing (46) and the driver disc (50) has a corresponding internal toothing (48). Starter according to claim 6, characterized in that the external toothing (46) of the threaded sleeve (42) and the internal toothing (48) of the driver disc (50) are each formed as a straight toothing. Starter according to claim 6 or 7, characterized in that the teeth are formed as triangular teeth. Starter according to one of the preceding claims, characterized in that the threaded sleeve (42) is made of plastic. Starter according to one of the preceding claims, characterized in that the threaded sleeve (42) is made of composite material. Starter according to one of the preceding claims, characterized in that the drive plate (50) via a freewheel (54) with the pinion shaft (58) is coupled. Starter according to one of the preceding claims, characterized in that the pinion shaft (58) via the threaded sleeve (42) is indirectly supported.

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