DE102015214810A1 - Starting device for an internal combustion engine - Google Patents

Abstract

A starting device for an internal combustion engine has in the transmission path from the motor shaft of the drive motor to the shaft of the starter pinion on a stop ring-shaft connection, wherein the stop ring is made of a shape memory material.

Description

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

State of the art

Are known starting devices for internal combustion engines, for example from the DE 10 2010 041 797 A1 , which are equipped with a starter pinion axially adjustable on a drive shaft, which is adjustable by means of a starter relay between a retracted disengagement position and an axially advanced engagement position with a ring gear of the internal combustion engine. In the engaged position, the starter pinion is driven by an electric starter motor whose drive motion is translated via a planetary gear. The axial feed motion generated by the starter relay is transmitted to a driver of a one-way clutch, which is integrally connected to a pinion shaft of the starter pinion. The driver sits on the drive shaft and is coupled via a coarse thread with the drive shaft. In the axial feed movement of the driver is adjusted along the helical thread, so that driver and starter pinion perform a rotational movement, which facilitates the meshing in the ring gear. The axial feed movement of the starter pinion is limited by a stop ring, which sits axially fixed on the drive shaft.

Disclosure of the invention

The starting device according to the invention for an internal combustion engine has a starter pinion, which is on a drive shaft axially between a disengaged position and an engagement position with a ring gear of the internal combustion engine adjustable and driven by an electric drive motor. The starting device is also equipped with a stop ring-shaft connection, which is in the transmission path from the motor shaft of the electric drive motor to a starter pinion bearing shaft. The stop ring is formed as a closed ring and made of a shape memory material. In its axial nominal position on the shaft, the stop ring is in a stable material phase.

This design has the advantage that the closed ring sits securely on the shaft even at high speeds and, in contrast to open stop rings no risk of radial expansion due to centrifugal forces, so that despite the high speeds a secure connection between the stop ring and the shaft is guaranteed. This eliminates a widening protection, which is required for open rings to prevent radial expansion and the stop ring radially engages. Accordingly, in the starting device according to the invention when using the stop ring-shaft connection reduces the required number of components.

The axially fixed position of the stop ring on the shaft is achieved in that the formed as a closed ring stop ring radially contracts due to its properties, which go back to the production of a shape memory tool in its axial nominal position and a high radial clamping force on the shaft exercises. The stop ring of the shape memory material has at least one stable material phase, optionally two stable material phases, wherein the stop ring is in its axial desired position on the shaft in a stable material phase. This has the effect on the one hand that the stop ring permanently retains its stable phase in the desired position and accordingly the clamping force exerted by the stop ring on the shaft remains permanently high. In every stable material phase, the stop ring is in a defined geometric position.

On the other hand, the transition to the stable material phase during assembly is achieved either automatically or with simple means. With the achievement of the stable material phase can be accompanied by a high radial clamping force, which securely holds the stop ring in its axial nominal position on the shaft. In the stable material phase, which occupies the stop ring in the axial desired position on the shaft, the stop ring against a non-stable material phase has a reduced inner diameter to ensure the desired high radial clamping force on the shaft.

The stop ring can be expanded prior to assembly and pushed in the expanded state on the shaft until it reaches the axial nominal position, then the stop ring is transferred to its stable material phase with reduced diameter. This embodiment is particularly suitable for stop rings made of a shape memory material with two stable material phases, wherein the stop ring is also in the radially expanded state during pushing in a stable material phase. This is maintained until reaching the axial nominal position, in which the stop ring is transferred to the second stable material phase with reduced diameter. The transfer takes place, for example, by heating the stop ring, for example by means of hot air.

According to an alternative advantageous embodiment, the stop ring is in unexpanded Condition pushed onto the shaft and radially expanded during sliding. In this case, a pseudoelastic effect of the shape memory material is exploited, in which the stop ring can be elastically expanded in a strong degree compared to another material. With the achievement of the axial nominal position, in which the respective shaft portion preferably has a reduced outer diameter, the stop ring goes over its stable material phase with reduced diameter. The transition to the stable material phase is preferably carried out automatically and without external intervention.

In an expedient embodiment, the shaft section on the shaft on which the stop ring assumes its axial setpoint position has a reduced outside diameter relative to adjacent shaft sections. The respective shaft section is designed, for example, as a circumferential groove on the shaft for receiving the stop ring. It is also possible that the shaft portion of the axial nominal position is limited only on one side by a circumferential wall, which for example represents the end face of a conical enlargement on the shaft, which must overcome the stop ring when pushed onto the shaft.

If the shaft portion of the axial nominal position does not have a reduced outer diameter, the connection between stop ring and shaft takes place solely by high clamping forces, which the stop ring exerts radially on the shaft due to its stable material phase. To increase the friction, if appropriate, the shaft surface can be roughened in the region of the shaft section of the axial nominal position.

According to an advantageous embodiment, the shaft has a groove for receiving the stop ring. The groove is achieved during assembly either in the pre-widened state of the stop ring or an expansion during the sliding onto the shaft, then the stop ring is transferred automatically or by external action in its stable material phase with reduced diameter. The groove has the advantage that the stop ring is accommodated axially positively in both directions on the shaft. In addition, the stop ring exerts a radial clamping force on the shaft.

As a shape memory material, various materials come into consideration, for example, a shape memory alloy, for example, a nickel-titanium alloy (NiTi). But there are also other shape memory materials or alloys into consideration, such as copper-zinc, copper-zinc-aluminum, copper-zinc-nickel or iron-nickel-aluminum.

As a shape memory material also a production of the stop ring of a bimetal is possible, which also has one, preferably two stable material phases.

According to a further expedient embodiment, the stop ring serves to axially limit the movement of the starter pinion in the starting device. The stop ring is, according to a first advantageous embodiment, placed on a pinion shaft and limits the axial movement of the spring-loaded starter pinion on the pinion shaft. The pinion shaft, including the pinion shaft axially adjustable and spring-loaded starter pinion is moved axially between the disengaged position and the engaged position. The relative axial movement of the starter pinion on the pinion shaft cushions a shock in the case of a tooth-on-tooth position between the starter pinion and the ring gear of the internal combustion engine. The starter pinion is pressed by the spring element acting on it axially against the stop ring on the pinion shaft and can axially dodge in a tooth-on-tooth position with the ring gear against the force of the spring element.

According to a further expedient embodiment, the shaft which receives the stop ring, the drive shaft which is driven to rotate by the drive motor. The starter pinion is, optionally including pinion shaft, axially adjusted on the drive shaft from the disengaged position to the engaged position with the ring gear of the internal combustion engine; this axial advancing movement is limited by the stop ring on the drive shaft.

In the front side of the starter pinion, according to a further advantageous embodiment, an axial receiving groove can be introduced, with which the starter pinion engages over the stop ring in the engaged position. This allows an axially space-saving design of the starting device, since the starter pinion is indeed limited by the stop ring in the axial movement, but due to the overlapping no additional space for the stop ring is required. Advantageously, concludes in the stop position, the end face of the starter pinion with the end face of the pinion shaft, so that on the one hand a sufficient axial travel of the starter pinion on the pinion shaft for compensation in the case of a tooth-on-tooth position is given and on the other hand, no additional space for arranging the stop ring on the pinion shaft is required.

According to yet another expedient embodiment, the shaft of the stop ring-shaft connection is the motor shaft of the electric drive motor. About the stop ring, the motor shaft is axially in the housing of Drive motor fixed. The fixation takes place in particular in the region of a bearing of the motor shaft in the housing, so that this camp performs the function of a fixed bearing. The axial fixing of the motor shaft of the drive motor may additionally or alternatively be provided for limiting the axial adjusting movement of the starter pinion on the shaft - the pinion shaft and / or the drive shaft.

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

1 a starting device for an internal combustion engine with a starter pinion, which is axially adjustable via a starter relay and is driven in rotation by an electric drive motor,

2 a top view of a stop ring, which consists of a shape memory material and is seated on a pinion shaft in the starting device,

3 the stop ring in side view,

4 a section along a pinion shaft with a seated starter pinion whose relative axial movement relative to the pinion shaft is limited by a stop ring of a shape memory material.

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

In the 1 illustrated starting device 1 for an internal combustion engine has a starter pinion 2 on, that for starting the internal combustion engine 4 in engagement with a sprocket 3 the internal combustion engine is brought. The starter pinion 2 is on a drive shaft 5 As shown by the double arrow mounted axially displaceable, wherein the starter pinion 2 for example, via a coarse thread with the drive shaft 5 connected is. The starter pinion 2 is between a retracted non-functional position and an advanced engagement position with the sprocket 3 the internal combustion engine 4 via a starter relay 6 adjusted, which is formed electromagnetically and a Bestrombare relay winding 7 as well as a lifting anchor 8th includes, when energized the relay winding 7 is pulled into this axially. The lifting anchor 8th is via an engaging lever 9 kinematically with the starter pinion 2 coupled, so that the axial adjustment movement of the lifting armature 8th between a rest position and an adjustment position in a corresponding axial adjusting movement of the starter pinion 2 between the non-functional position and the engaged position is used.

The rotating drive movement on the drive shaft 5 or the starter pinion 2 is powered by an electric drive motor 11 generated by a planetary gear 12 with the drive shaft 5 is coupled. Upon actuation of the electric drive motor 11 becomes the drive shaft 5 and with it the starter pinion 2 set in rotation. Between the planetary gear 12 and the drive shaft 5 a freewheel device can be arranged to decouple the starter pinion from the drive motor after the start of the internal combustion engine.

The starting device 1 is a control unit 10 assigned via which the functions of the starter relay 6 and the drive motor 11 to be controlled.

In an axial adjusting movement of the lifting armature 8th upon actuation of the starter relay 6 When reaching the adjustment position by a kinematic coupling of the switching element with the actuating movement of the lifting armature 8th the electric current for the starter motor 11 turned on, so that the starter motor 11 sets in motion and the wave 5 as well as the starter pinion 2 rotating drives.

In the 2 and 3 is a stop ring 13 shown in accordance with 4 on a pinion shaft 14 is arranged and to limit the axial relative movement of the starter pinion 2 on the pinion shaft 14 serves. The pinion shaft 14 sits on the drive shaft 5 ( 1 ) and is connected via a coarse thread with the drive shaft. During a feed movement of the pinion shaft 14 generated by the starter relay 6 , guides the pinion shaft 14 due to the coupling via the coarse thread with the drive shaft from a relative rotational movement to the drive shaft and thereby facilitates the meshing in the ring gear of the internal combustion engine.

The starter pinion 2 is held axially displaceable relative to a collar of the pinion shaft and is of a spring element 15 against the stop ring 13 energized, located on the collar of the pinion shaft 14 located adjacent to its end face. In the pinion shaft 14 a groove is introduced, which is adjacent to the front side and in the stop ring 13 is used.

In the advancing movement of pinion shaft 14 including starter pinion 2 towards the ring gear of the engine, the starter pinion 2 in the case of a tooth-on-tooth position with the ring gear against the force of the spring element 15 from its stop position on the stop ring 13 flinch. After meshing is the starter pinion 2 by the spring element 15 axially again against the stop ring 13 pressed.

The stop ring 13 is made of a shape memory material, for example of a nickel-titanium alloy (NiTi) and has at least one, preferably two stable material phases, in which the inner diameter of the stop ring 13 different. For mounting the stop ring 13 on the pinion shaft 14 First, the stop ring 13 radially expanded and in the expanded state, which advantageously represents a stable material phase, until reaching the axial nominal position in the region of the groove on the pinion shaft 14 postponed. The inner diameter of the stop ring 13 has in the expanded state advantageously an excess over the outer diameter of the pinion shaft 14 on, allowing the sliding of the stop ring 13 on the pinion shaft 14 force-free.

After reaching the axial nominal position of the stop ring is transferred to its second stable material phase, in which the stop ring has a reduced inner diameter. The shrinking process when transferring to the second stable material phase is achieved, for example, in that the stop ring 13 is heated, for example by means of hot air. In the second stable material phase is the inner diameter of the stop ring 13 reduced, in particular so far reduced that a radial clamping force on the bottom of the receiving groove on the pinion shaft 14 is exercised. In addition, there is a positive reception in both axial directions due to the limitation by the groove walls.

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 102010041797 A1 [0002]

Claims (10)

Starting device for an internal combustion engine, with a starter pinion ( 2 ) mounted on a drive shaft axially between a disengaged position and an engagement position with a sprocket ( 23 ) of the internal combustion engine ( 4 ) adjustable and by a drive motor ( 11 ) is drivable with a stop ring-shaft connection in the transmission path from the motor shaft of the drive motor ( 11 ) to a starter pinion ( 2 ) carrying wave ( 14 ), characterized in that the stop ring ( 13 ) is formed as a closed ring and is made of a shape memory material, wherein the stop ring ( 13 ) in its axial nominal position on the shaft ( 14 ) is in a stable material phase. Starting device according to claim 1, characterized in that in the shaft ( 14 ) a groove for receiving the stop ring ( 13 ) is introduced. Starting device according to claim 1 or 2, characterized in that the stop ring ( 13 ) is made of a shape memory alloy, such as a nickel-titanium alloy (NiTi). Starting device according to one of claims 1 to 3, characterized in that the stop ring ( 13 ) the stop ring-shaft connection an axial movement of the starter pinion ( 2 ) limited. Starting device according to claim 4, characterized in that the shaft of the stop ring-shaft connection a pinion shaft ( 14 ) and the stop ring ( 13 ) the axial movement of the spring-loaded starter pinion ( 2 ) on the pinion shaft ( 14 ) limited. Starting device according to claim 4 or 5, characterized in that in the end face of the starter pinion ( 2 ) is introduced an axial receiving groove with which the starter pinion ( 2 ) the stop ring ( 13 ) engages in the engaged position. Starting device according to claim 6, characterized in that in the stop position, the end face of the starter pinion ( 2 ) with the end face of the pinion shaft ( 14 ) completes. Starting device according to one of claims 1 to 7, characterized in that the shaft of the stop ring-shaft connection is the motor shaft of the drive motor and the stop ring ( 13 ) The motor shaft axially fixed in the housing of the drive motor. Method for fastening a stop ring ( 13 ) on a wave ( 14 ) in a starting device ( 1 ) according to one of claims 1 to 8, wherein the stop ring ( 13 ) on the shaft ( 14 ) and after reaching the axial nominal position on the shaft ( 14 ) for shrinking the diameter of the stop ring ( 13 ) is heated. Method for fastening a stop ring ( 13 ) on a wave ( 14 ) in a starting device ( 1 ) according to one of claims 1 to 8, wherein the stop ring ( 13 ) when pushed onto the shaft ( 14 ) is expanded and returns to a stable output diameter after reaching the axial target position.

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