Transmitter for a synchronising assembly of a manual transmission and a method for producing a transmitter

A transmitter for a synchronizing assembly of a manual transmission has a transmitter disk and at least one clutch disk which is arranged on a side surface of the transmitter disk. The clutch disk and the transmitter disk are fixedly connected together by local welding points. A method for producing a transmitter for a synchronizing assembly of a manual transmission consists of providing a clutch disk and a transmitter disk. Then, the clutch disk and the transmitter disk are fastened together by means of projection welding. Finally, the thus formed assembly is hardened.

The invention relates to a transmitter for a synchronising assembly of a manual transmission, having a transmitter disk and at least one clutch disk which is arranged on a side surface of the transmitter disk. The invention also relates to a method for producing a transmitter for a synchronising assembly of a manual transmission.

BACKGROUND OF THE INVENTION

A synchronising assembly of a manual transmission, as used in particular in motor vehicles, is used, in general terms, to establish a rotationally-fixed connection between a transmission shaft and a gear wheel or toothed wheel arranged on the transmission shaft as an idler wheel. In a first step of the gear-shifting process, the synchronising assembly ensures that the rotational speed of the gear wheel to be shifted matches the rotational speed of the transmission shaft. In a second step, a rotationally-fixed connection is established between the transmission shaft and the gear wheel. The corresponding gear is then shifted.

A widely used type of synchronising assembly is known under the name “BorgWarner synchronisation”. This synchronising assembly uses a shift collar which is arranged on a synchronising body in a rotationally-fixed but axially displaceable manner, said body being connected to the transmission shaft for conjoint rotation therewith. The shift collar can be displaced from an initial position in the axial direction to a gear wheel. A synchronising ring is initially activated hereby which synchronises the rotational speed of the gear wheel with the rotational speed of the transmission shaft. As soon as this process is complete, the shift collar can be further displaced in the axial direction until it establishes a rotationally-fixed connection with the corresponding gear wheel.

As an alternative to this type of synchronising assembly, a type which uses the transmitter mentioned in the introduction is known. An example of this can be seen in DE 10 2010 036 278 A1. In general terms, the transmitter combines the synchronising body and the shift collar in one component which is mounted so as not to rotate relative to the transmission shaft and can be displaced in the axial direction. If the transmitter is displaced in the axial direction from a neutral position, a synchronising ring (or even an assembly consisting of a plurality of synchronising rings) is initially activated, whereby the rotational speed of the corresponding gear wheel is synchronised with the rotational speed of the transmission shaft. In a second step, the transmitter can then be interconnected, whereby a rotationally-fixed connection is established between the transmission shaft and the corresponding gear wheel.

The object of the invention is to provide a transmitter which can be produced at low cost.

BRIEF DESCRIPTION OF THE INVENTION

In order to achieve this object, a transmitter is provided which has a transmitter disk and at least one clutch disk which is arranged on a side surface of the transmitter disk. The clutch disk and the transmitter disk are fixedly connected together by local welding points. These can be produced quickly, reliably and at low cost, for example by resistance welding. Since the torque is transmitted from the transmission toothed wheels to the transmission shaft substantially directly via the clutch disks and not via the transmitter disk, the welding points are also not subjected to any particularly high loads.

Projections are preferably provided which form the welding points. This ensures that the welding points are produced precisely at the desired positions.

In accordance with a preferred embodiment, spacers are provided, on which the projections are formed, in particular on the transmitter disk. The spacers allow a pressure piece to be arranged in the transmitter disk, the dimensions of which pressure piece are larger in the axial direction than the thickness of the transmitter disk. This allows in particular a comparatively robust compression spring to be arranged in the transmitter disk.

In order to achieve the above-mentioned object, a method for producing a transmitter for a synchronising assembly of a manual transmission is also provided in accordance with the invention, said method comprising the following steps: initially, a clutch disk and a transmitter disk are provided. Then, the clutch disk and the transmitter disk are fastened together by means of projection welding. Then, the thus formed assembly is hardened. This sequence of welding and hardening ensures that the material has, during welding, the optimum properties therefor.

The assembly can either be freely hardened, i.e. hardened and quenched or it is also possible for the assembly to be hardened on a mandrel which, for example, engages into an internal toothed arrangement of the clutch disk and thus limits the distortion due to hardening at that location.

In accordance with a preferred embodiment, provision is made that the transmitter disk is provided with at least one recess, and that after the assembly is hardened a pressure piece is mounted in the recess. The pressure piece can be inserted into the recess allocated thereto in an extremely simple manner in mechanical terms, wherein it is optionally guided between the clutch disks.

In accordance with a preferred embodiment of the invention, provision is made that the pressure piece is clipped into the recess. This ensures that the pressure piece remains in the recess allocated thereto after being assembled without any further aids.

In accordance with a preferred embodiment of the invention, provision is made that the pressure piece is provided with a base part and a guide part, wherein the base part is located between two clutch disks which are arranged on sides of the transmitter disk facing away from each other, and that the guide part is guided in the axial direction between edges of the recess which are opposite one another in the circumferential direction. This design produces a particularly precise guidance of the pressure piece in the recess, whereby the shifting behaviour is optimised.

Advantageous embodiments of the invention are apparent from the dependent claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1schematically shows a synchronising assembly which comprises two transmission toothed wheels1,2which can each be connected to a transmission shaft3for conjoint rotation therewith depending upon the shifted gear. For this purpose, a transmitter10is provided which can be adjusted in the axial direction relative to the transmission shaft3.

Where the terms “axial” or “radial” are used hereinafter, they refer to the rotational axis of the transmission shaft3and of the transmitter10.

The basic design of the synchronising assembly is explained hereinafter with reference toFIGS. 1 to 5, whilst details will be explained further hereinafter with reference toFIGS. 6 to 22.

The transmitter10comprises a transmitter disk12which is provided with a clutch disk14on each of its two side surfaces. Each clutch disk14comprises, on its radially inner circumference, a transmission shaft toothed arrangement16and, on its radially outer circumference, a clutch toothed arrangement18(see in particularFIG. 2).

The transmission shaft toothed arrangements16of the clutch disks14are accommodated on an external toothed arrangement20of a transmitter sleeve22in a rotationally-fixed but axially displaceable manner. In turn, the transmitter sleeve22is arranged on the transmission shaft3in a rotationally-fixed manner. For this purpose, the transmitter sleeve22can be provided with an internal toothed arrangement24(see in particularFIGS. 3 to 5).

The clutch toothed arrangement18of each clutch disk14is provided so as to co-operate with a gear wheel clutch toothed arrangement26allocated thereto and provided on the transmission toothed wheels1,2. In the illustrated exemplified embodiment, each gear wheel clutch toothed arrangement26is provided on the inner surface of a friction ring28which is provided on its outer side with a slightly conical friction surface30. Each friction ring28is connected, e.g. welded or soldered, to the transmission toothed wheel1,2allocated thereto for conjoint rotation therewith.

Arranged on the transmitter disk12are two synchronising rings32which lie one on either side of the transmitter disk12and are provided so as to co-operate with the friction surfaces30of the friction rings28. For this purpose, the synchronising rings32are provided with a friction lining34on their inner surface.

The synchronising rings32are basically connected to the transmitter disk12for conjoint rotation therewith but they can also rotate relative thereto about a small angular range. Furthermore, the synchronising rings32are attached in the axial direction to the transmitter disk12but they can also be adjusted to a certain extent in the axial direction starting from a centre or initial position.

Each synchronising ring32is provided with three different types of lugs which extend through allocated openings, recesses or apertures in the transmitter disk, or at least extend into same: connecting lugs36,37, stop lugs38and locking lugs40.

The connecting lugs36,37are used to mechanically connect the two synchronising rings32to each other in the axial direction. For this purpose, each synchronising ring32has a connecting lug36which has a wide head at its free end and transitions into the synchronising ring-side section of the connecting lug36via a narrower neck.

Each connecting lug37has an aperture which has a larger section adapted to the dimensions of the head of the connecting lug36and a narrower section adapted to the dimensions of the neck of the connecting tug36.

The connecting lugs36,37extend, when engaged with each other, through two openings42, allocated thereto, in the transmitter disk. The width of the openings42in the circumferential direction is greater than the width of the connecting lugs36,37in the circumferential direction.

The stop lugs38have a constant width and extend into apertures44which are likewise provided in the transmitter disk12. The width of the apertures44in the circumferential direction is slightly greater than the width of the stop lugs38in the circumferential direction.

The locking lugs40each extend into a recess46in the transmitter disk12. The mutually facing ends of the locking lugs40in the initial position are located opposite each other and centrally within the recess46(see in particularFIG. 4).

Each locking lug40comprises, in proximity to its free end, two locking surfaces48which face away from each other and extend in an inclined manner relative to the extension direction of the locking lugs40. In this case, the locking surfaces48form, with an extension of the outer edges of the locking lugs40, an angle in the order of magnitude of 60°.

The locking surfaces48co-operate with the edges50of the corresponding recess46, which edges are opposite each other and extend in parallel with each other, and, more specifically, the locking surfaces each co-operate with a bevel52which is provided on the corresponding edge. The orientation of the bevels52corresponds to the orientation of the locking surfaces48so that these can lie flat against each other.

The locking lugs40comprise, on the radially inner side of each of their free ends, a centring bevel54(see in particularFIG. 4), on which an outwardly directed pressure surface56of a pressure piece58engages.

Each pressure piece58comprises a guide part60which is held between the edges50of the corresponding recess46in the axial direction, a base part62which is arranged on the radially inner end of the recess46, and a compression spring64which exerts a force upon the guide part60and the base part62, said force intending to move the guide part60away from the base part62.

As can be seen in particular inFIG. 2, the transmitter comprises four locking lugs40per synchronising ring32, which lugs are evenly spaced apart from each other in the circumferential direction, and two connecting lugs36,37which lie diametrically opposite one another, and two stop lugs38which lie diametrically opposite one another. The diameter defined by the two connecting lugs36,37is perpendicular to the diameter defined by the two stop lugs38. In other words: the connecting lugs and the stop lugs are arranged so as to be staggered with respect to one another by an angle of 90°.

The process of shifting a gear and synchronising the rotational speeds of the transmission shaft and of the transmission toothed wheel to be shifted is basically performed in the same manner as described in DE 10 2010 036 278 A1: if a gear is to be shifted, the transmitter disk12is displaced in the axial direction by means of an actuating device (not shown herein). The two synchronising rings32connected together are entrained in the axial direction because the pressure surfaces56of the pressure pieces58mounted on the transmitter disk12lie between the two V-shaped centring bevels54and the spring force provided by the compression springs64produces sufficient friction.

As soon as the synchronising ring32comes into engagement with the friction surface30, allocated to the transmission toothed wheel to be shifted, the synchronising ring (assuming a difference in rotational speed between the transmission toothed wheel and the transmission shaft) is entrained in the circumferential direction until one of the outer edges of each of the two stop lugs38comes to lie against the edge of the corresponding aperture44in each case. The position of the synchronising rings is hereby defined in the circumferential direction.

If, in this state, the transmitter disk12is further displaced in the axial direction, it is displaced axially relative to the synchronising rings32because the active synchronising ring32is supported in the axial direction on the friction surface30of the transmission toothed wheel to be shifted. By way of this axial displacement of the transmitter disk12relative to the synchronising ring32, one of the bevels52at the edge of each recess46comes to lie against one of the locking surfaces48on each of the locking lugs40, and in particular the ones which have been moved towards each other owing to the relative movement between the synchronising rings32and the transmitter disk12.

The transmitter disk12can only then be further adjusted in the axial direction if the synchronising rings32can, via the mutually co-operating locking surfaces48of the synchronising rings and bevels52of the transmitter disk, be rotated back in the circumferential direction to the extent that the locking surfaces48no longer lie against the bevels52but rather the outer edges of the locking lugs40extending in the axial direction slide along the edges50of the recesses46. However, it is only possible to re-adjust the synchronising ring32in the circumferential direction (expressed simply) when the rotational speeds of the transmission toothed wheel to be shifted and the transmission shaft match one another. Specifically: the synchronising ring32can then be unlocked if the unlocking moment (reverse torque), resulting from the shifting force and the locking geometry (bevel angle and coefficient of friction) is greater than the synchronising moment on the friction surface of the synchronising ring.

If the rotational speeds of the transmission toothed wheel and the transmission shaft match one another, the synchronising rings32are rotated slightly in the circumferential direction (owing to the effect of the bevels52on the locking surfaces48), and therefore the transmitter disk12can be further shifted in the axial direction. The guide parts60of the pressure pieces58yield radially inwards because they are adjusted inwardly by the centring bevels54.

The transmitter disk12is adjusted in the axial direction to the extent that the clutch toothed arrangement18of the clutch disk14located at the front in the adjusting direction engages into the corresponding gear wheel clutch toothed arrangement26. As a result, a rotationally-fixed connection is established from the transmission shaft3, via the transmitter sleeve22, the transmission shaft toothed arrangement16, the clutch disk14, the clutch toothed arrangements18and the gear wheel clutch toothed arrangement26, to the corresponding transmission toothed wheel.

The design of the pressure pieces58and their attachment in the recesses46of the transmitter disk12will be explained hereinafter with reference toFIGS. 6 to 17.

The guide part60of each pressure piece58consists of synthetic material and is formed in particular as an injection moulded part. It comprises a cross-bar70(see in particularFIGS. 9, 10 and 12), wherein two latching arms72extend in parallel with each other in the same direction from the ends of the cross-bar which face away from each other. The cross-bar70is provided with the pressure surface56on the side opposite the latching arms72. This pressure surface is slightly curved, wherein the radius of curvature which determines the curvature in the circumferential direction is on a central plane M on the side towards which the two latching arms72also extend (see the indicated radius r inFIG. 12). The radius r approximately corresponds to the radius on which the locking lugs40lie.

The outer edges of the latching arms72facing away from each other are each provided with a guide contour74which is formed by guide surfaces76arranged in a V-shape (seeFIG. 7a). The apexes of the two V-shaped guide contours74are rounded and the two apexes face each other. In other words: the guide contours74are formed as grooves along the outer edges of the latching arms72.

Designs other than the V-shape can also be used in the region of the contact between the latching arms72and the transmitter disk. Examples are shown inFIGS. 7bto7e.

InFIG. 7b, the edge of the transmitter disk12is concave on the side thereof facing the corresponding latching arm72, and specifically has a rectangular groove (as seen in cross-section). A complementarily convex outer edge of the corresponding latching arm72engages into said groove.

InFIG. 7c, the edge of the transmitter disk12is likewise concave on the side thereof facing the corresponding latching arm72, and specifically is formed as a depression with a curved bottom (as seen in cross-section). A complementarily convex outer edge of the corresponding latching arm72engages into said depression.

InFIG. 7d, the edge of the transmitter disk12is convex on the side thereof facing the corresponding latching arm72, and specifically has a rectangular protrusion (as seen in cross-section). Said protrusion is accommodated in a complementary groove having a rectangular cross-section in the outer edge of the corresponding latching arm72.

InFIG. 7e, the edge of the transmitter disk12is likewise convex on the side thereof facing the corresponding latching arm72, and specifically is formed as a protrusion with a curved end face (as seen in cross-section). Said protrusion is accommodated in a complementary convex depression in the outer edge of the corresponding latching arm72.

Formed on each of the mutually facing inner edges of the latching arms72are two V-shaped sliding guide surfaces78(see in particularFIG. 11). The apex of the V-shaped contour is also rounded in this case and the apexes fie opposite one another. The two V-shaped contours on the inner side and outer side of the latching arms72are thus oriented in the same direction. However, the angles are different. Whilst the guide surfaces76together form an angle of less than 90°, the sliding guide surfaces78together form an angle of greater than 90° (likewise as measured on the “inner side” of the V-shaped contour). The crown angle for the guide contour74is in the order of magnitude of 60° whilst the crown angle for the sliding guide contour formed by the sliding guide surfaces78is in the order of magnitude of 120°.

The two latching arms72are each provided with a latching configuration80on their inner side on the free end, said configuration being in the form of a bead or protrusion (see in particularFIG. 12).

The base part62(see in particularFIGS. 9 and 14 to 17) comprises a planar bottom part82, from which two post-like protrusions84extend, which protrusions together form a spring bearing for the compression spring64. A circular depression86is provided in this case between the two protrusions84and is used to receive an and of the compression spring64. However, the depression is not absolutely necessary.

The two protrusions84are curved on their mutually facing inner sides, wherein the radius of curvature is adapted to the outer diameter of the compression spring64. The outer surfaces, facing away from each other, of the protrusions84are provided with sliding guide surfaces88which are inclined in the same manner as the sliding guide surfaces78on the guide part60. The sliding guide surfaces78of the guide part60form, together with the sliding guide surfaces88of the base part62, a sliding guide, along which the guide part60is guided and received thereon so as to be displaceable relative to the base part62.

Each of the sliding guide surfaces88of the protrusions84of the base part62is provided with a latching configuration90which likewise is in the form of a bead or protrusion. The latching configuration90is arranged, as seen starting from the bottom part82, in the order of magnitude of a third of the height of the protrusions84.

The smaller end faces, facing away from each other, of the bottom part82of the base part62are each formed as clip-in ends92. For this purpose, small, bead-like protrusions are provided on the end faces.

Each pressure piece58forms a pre-assembled unit (seeFIG. 9). This unit consists of the base part62, the guide part60and the compression spring64.

In order to assemble a pressure piece, the compression spring64is inserted between the two protrusions84. Then, the guide part60is placed on the base part62such that the latching configurations80of the latching arms72latch behind the latching configurations90of the protrusions84(see the state inFIG. 9). In this state, the compression spring64is slightly biassed. However, it is not able to separate the guide part60from the base part62because its spring force is lower than the holding force of the form-fitting coupling of the latching configurations80and90.

The pressure pieces58are inserted into the recesses46of the transmitter disk12such that the guide surfaces76co-operate with the bevels52on the edges50of the recesses46(see in particularFIG. 7). The guide parts60are hereby accommodated in the recesses46so as to be displaceable in the radial direction, but are reliably held therein in the axial direction.

Insertion of the pressure pieces58into the recesses46is facilitated by insertion contours53which are attached to the edges50on the radially inner side (see in particularFIG. 6).

Upon assembly of the pressure pieces58in the recesses46of the transmitter disk12, the clip-in ends92of the base parts62engage into a suitably formed holding section47on the radially inner end of each recess46(see in particularFIG. 6). As a result, the pressure pieces58are pre-assembled in the transmitter disk12(see alsoFIG. 8).

If the synchronising rings32are mounted on the transmitter disk12, the pressure surfaces56of the pressure pieces58adjoin the two mutually facing centring bevels54of the locking lugs40(seeFIGS. 4 and 6). Since the pressure surfaces56are curved in the circumferential direction, a line contact is produced.

When the transmitter disk12is mounted on the transmitter sleeve22, the base part62lies on the outer toothed arrangement20of the transmitter sleeve22(seeFIG. 6) and therefore the base part62is supported in the radial direction. Therefore, if the guide part60is adjusted inwardly in the radial direction (in an interconnected position of the transmitter disk12) and thus the compression spring64is biassed to a greater extent than in the initial state, the base part62also cannot be pushed inwards out of the holding section47.

The manner in which the clutch disks14are fastened to the side surfaces of the transmitter disk12will be described hereinafter with reference toFIGS. 18 to 22.

The two clutch disks14are welded to the transmitter disk12, and in particular by projection welding (i.e. resistance welding at predetermined points).

Each clutch disk14is fastened to the transmitter disk12at four welding points100evenly spaced apart from each other in the circumferential direction. These are defined by material protrusions102which are produced alternately in opposite directions by plastic deformation of the material of the transmitter disk12, and in particular in a direction perpendicular to the plane which is defined by the transmitter disk (perpendicular to the plane of the drawing ofFIG. 18and in the direction of the arrow P inFIG. 19). A depression104is thereby formed on the side opposite the material protrusion102.

The material protrusions102which subsequently form the welding points100are formed on spacers106which are likewise formed by plastic deformation of the material of the transmitter disk12. The spacers106are produced in that the transmitter disk12is provided with an embossed portion108(see in particularFIG. 19) on the opposite side.

As can be seen inFIG. 18, the spacers106and the embossed portions108are each arranged in pairs in the same sequence between adjacent recesses46for the pressure pieces58.

The spacer106ensures that a distance a is provided in each case between the transmitter disk12and the clutch disks14(see for exampleFIG. 22). The distance a allows a compression spring64to be used which has a diameter greater than the thickness of the transmitter disk12. A spring having a higher spring constant can hereby be used.

FIG. 19illustrates the spacers106in a state in which the transmitter disk12is produced as a blank. The material protrusions102are provided in this state.

In order to connect the transmitter disk12to the two clutch disks14, these are arranged and oriented on the two side surfaces of the transmitter disk12. Then, they are fastened to one another by projection welding or resistance welding, wherein the material protrusions102melt on the spacers106so that the clutch disks14lie flat on the spacers106. This can be seen on the one hand inFIG. 22and on the other hand inFIG. 20in which the spacers106are shown without the material protrusions102. Welding points100remain in place of the material protrusions102, wherein the clutch disks14are materially bonded to the transmitter disk12at said welding points.

After the clutch disks14have been welded to the transmitter disk12, the thus formed assembly is hardened. This can occur in that the assembly is heated and then quickly cooled.

Depending upon the distortion due to hardening which is to be expected and can be tolerated, the assembly can either be freely hardened or even hardened on a mandrel, the outer contour of which corresponds precisely to the transmission shaft toothed arrangement16of the clutch disks14; it is hereby ensured that the transmission shaft toothed arrangements16have a desired contour even after hardening.

After hardening, the pressure pieces58can be mounted in the recesses46where the base parts62latch into the holding sections47.