WO2019207038A1

WO2019207038A1 - Park lock system for a vehicle driveline

Info

Publication number: WO2019207038A1
Application number: PCT/EP2019/060603
Authority: WO
Inventors: Roel VERPOORTEN; Philip Patrick Lydia VANDEPUT
Original assignee: Punch Powertrain NV
Current assignee: Punch Powertrain NV
Priority date: 2018-04-26
Filing date: 2019-04-25
Publication date: 2019-10-31
Anticipated expiration: 2020-10-26
Also published as: CN112105832B; BE1026240A1; CN112105832A; BE1026240B1

Abstract

A park lock system (10) for a vehicle driveline (12), comprising a driveline gear wheel (14) and a lock gear part (22) having a plurality of spaced apart lock gear part teeth (24) and an alignment tooth (38). The lock gear is axially movable from a lock position to a release position. The lock gear part (22) is also tangentially moveable arranged and biased by biasing means in an initial position. A tip of the alignment tooth is tangentially offset relative to the tips of the lock gear part teeth (24) and protrudes beyond the lock gear part teeth towards the gear wheel (14) so that proper and shock free engagement between the lock gear part teeth (24) and the gear wheel teeth (16) is always guaranteed.

Description

Park lock system for a vehicle driveline

FIELD

The invention relates to a park lock system for a vehicle driveline.

BACKGROUND

Park lock systems are used to immobilize a vehicle when the vehicle is parked and not in use. These systems lock wheels of the vehicle so that they can not rotate and the vehicle remains in a standstill. This is true both for manual and automatic transmission. In a vehicle with a manual transmission the engine can be used to immobilize the vehicle whilst parking by putting the transmission into one of the drive gears. But even so auxiliary devices are wanted to immobilize the vehicle. The most common is the hand brake.

With an automatic transmission it is not possible to use the engine to immobilize the vehicle. In a vehicle with an automatic transmission, due to the construction of the commonly used fluid coupling, there is no directly fixed mechanical coupling between the engine and the wheels. Also for a dual-clutch transmission there is no direct mechanical coupling between the engine and the wheels. In both cases a park lock system is then a way to immobilize the vehicle.

Park lock systems are commonly integrated into transmissions and/or other vehicle driveline components and are used to immobilize and secure a rotatable part of a vehicle driveline. For this, park lock systems are known which couple to a part of the transmission itself, e.g. a transmission gear, or to another gear wheel, which is coupled for common rotation to the transmission. An example of such a known system is US 3,990,541 (US’541). US’541 discloses a park-lock mechanism for a transmission wherein a pivotable latch is engagable with a gear in a vehicle transmission, thus securing the gear in a non-rotatable position when the vehicle is parked.

The pivotable latch includes two lugs which are spaced apart at a distance different from one or a multiple of the pitch distance of the teeth of the gear which the latch engages for locking to secure against rotation. In this way the mechanism of this invention assures that the latch by means of one of the two lugs thereof, will always and immediately be set in the latching and secure position when desired, and the gear need not be rotated to a certain position to achieve the latching described.

Another example of such a known system is US 2016/0097443 Al (US’443). In US’443 a differential case is rotatably mounted in a driveline component housing. The differential case is provided with a plurality of gear teeth that extend circumferentially about the differential case and which are engaged by a drive pinion for rotating the differential case within the driveline component housing. For the park lock function, the differential case is provided with a plurality of first face teeth. The driveline component housing is provided with a plurality of first radial teeth. An annular lock element comprises a plurality of second radial teeth that are in engagement with the first radial teeth. The annular lock element also comprises second face teeth which in engage with the first face teeth in a first axial position of the annual lock element, which forms a lock position. Thus, the differential case is rotatably locked with respect to the driveline component housing.

The annular lock element is axially slidably mounted and can be slid to a second axial position in which the second face teeth of the annular element are disengaged from the first face teeth so that the differential case is rotatable within the driveline component housing.

The solutions of the know systems have problems of there own. In US’541 only one tooth (lug) is used for engagement, resulting in a need for a rather high engagement force due to the small contact surface. A problem of US 2016/0097443 is that the when the tops of the first face teeth are opposite the tops of the second face teeth, the annular element cannot be slid into the first axial position and the thus the lock position cannot be realized. It is only after some rotation of the differential case, i.e. for a vehicle after some movement of the vehicle that the annular element can be brought into the first axial position so as to realize the lock function which in many cases may lead to a shock load and undesired movement.

SUMMARY OF THE INVENTION

An object of the invention is to provide a park lock system for a vehicle driveline with an improved locking mechanism.

To that end, the invention provides a park lock system for a vehicle driveline according to claim 1.

More particular, the park lock system according to the invention comprises a gear wheel that is coupled to a rotatable member of the driveline, the gear wheel comprising a plurality of circumferentially spaced apart gear wheel teeth, which are aligned along a gear wheel teeth circle having a gear wheel circle radius, a lock gear part, comprising a plurality of spaced apart lock gear part teeth, wherein tips of the lock gear part teeth are spaced apart at a lock gear part teeth pitch. The lock gear part is moveably arranged along a first axis so as to be moveable towards and away form the gear wheel. The lock gear part has a lock position in which the lock gear part teeth engage the gear wheel teeth so that rotation of the gear wheel is blocked, and the lock gear part has a release position in which the lock gear part is moved away from the gear wheel so that the lock gear part teeth are disengaged from the gear wheel teeth so that the gear wheel is rotatable. The lock gear part is moveable arranged along a part of a circular line having a radius that is substantially equal to the gear wheel circle radius. The lock gear part comprises an alignment tooth having a tip which is tangentially offset of with respect to lock gear part teeth tips. The alignment tooth has a protruding position wherein the tip of the alignment tooth is protruding beyond the tips of the lock gear part teeth towards the gear wheel.

The lock gear part may be movable in two directions along the part of the circular line.

The lock gear part may comprise an annular body, and the lock gear part teeth may be spaced apart along a full circle.

The park lock system may comprise biasing means which are configured for biasing the lock gear part in an initial position and which allow movement of the lock gear part along the part of the circular line.

The biasing means may comprise at least one biasing spring pushing the lock gear part into the initial position, wherein the at least one biasing spring allows the lock gear part to move in a direction along the part of the circular line.

The alignment tooth may be movable with respect to the lock gear part teeth in a direction substantially parallel to the first axis.

The alignment tooth may be movable between an alignment position wherein the tip of the alignment tooth is aligned with the tips of the lock gear part teeth in an addendum plane of the lock gear part teeth, and the protruding position.

The park lock system may further comprise an alignment tooth spring which pushes the alignment tooth into the protruding position.

The alignment tooth spring may be provided in the lock gear part.

The alignment tooth may advantageously have a profile different from the profile of the lock gear part teeth.

Furthermore, the alignment tooth may have a non- symmetrical profile.

The park lock system may further comprise an actuator assembly which, when actuated, pushes the lock gear part into the lock position. The actuator assembly may comprise a pressing block of which an outer surface pushes directly on an outer surface of the lock gear part, a self-locking trapezoidal spindle, and an actuator connected to the self locking trapezoidal spindle, configured to rotate the self-locking trapezoidal spindle. The self-locking trapezoidal spindle may be rotatably connected with a treaded hole in the pressing block. When the self-locking trapezoidal spindle rotates in a first direction it pushes the pressing block towards and onto the lock gear part, so that the pressing block pushes the lock gear part from the release position to the lock position. When the trapezoidal spindle rotates in a direction opposite the first direction it pulls the pressing block away from the lock gear part.

Instead or additionally, the actuator assembly may comprise at least one pull spring pulling the lock gear part in the direction of the release position.

The at least one pull spring may also constitute the biasing means which are configured for biasing the lock gear part in an initial position and which allow movement of the lock gear part along the part of the circular line.

The lock gear part teeth may be rounded off and/or chamfered.

The lock gear part may be mounted in a lock gear part chamber bounded by a lock gear part housing. Preferably the lock gear part housing may be integral to a clutch or transmission housing of a vehicle.

A movement of the lock gear part along the part of the circular line may be bounded by a wall of the lock gear part housing.

The invention further provides a vehicle, comprising a park lock system according to the invention.

When the lock gear part is moved towards the gear wheel the lock gear part teeth and the gear wheel teeth will engage. An advantage of the invention is that multiple teeth are used for engagement, resulting in less rotational force or torque per teeth as opposed to using only one teeth or lug. Only when the tips of the lock gear part teeth are aligned exactly in the middle between the tips of the gear wheel teeth the lock gear part can reach its lock position without the need for relative displacement in a tangential direction along the gear wheel teeth circle. When this alignment does not occur, the lock gear part teeth and gear wheel teeth will engage before the lock gear part reaches its lock position and thereby force the lock gear part in a tangential position in which the tips of the lock gear part are aligned exactly in the middle between the tips of the gear wheel teeth. By virtue of the tangentially movable lock gear part, the gear wheel does not have to rotate during engagement. This has the advantage that the vehicle driveline does not rotate. Because the gear wheel can stop in any given, arbitrary position, there is a chance that the tips of the lock gear part teeth and gear wheel teeth are aligned directly opposite to each other. In that case, moving the lock gear part along the first axis from the release position towards the gear wheel would amount to pushing the tips of both set of teeth onto each other. Such situation may prevent an effective park lock engagement.

Alternatively, one set of teeth may give way, resulting in a movement of either or both the gear wheel and/or lock gear part and consequently in a sudden and rapid movement of the lock gear part towards its lock position accompanied with a resulting shock load. The presence of the alignment tooth in combination with the tangentially movable lock gear part solves this unwanted movement and ensures an effective park lock engagement in all situations.

The present invention will be further elucidated with reference to figures of exemplary embodiments. The embodiments may be combined or may be applied separately from each other.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows a perspective side view of a transmission of a vehicle driveline with mounted thereupon an embodiment of the park lock system; Fig. 2 shows a top view of the transmission of Fig. 1;

Fig. 3 is a perspective side view of the park lock system of Fig. 2 along the direction of the arrows A and A’ shown in Fig. 2;

Fig. 4 shows a cut away view of the of the park lock system along line A- A’.;

Fig. 5 shows an enlarged detail of the cut away view of Fig. 4; and

Fig. 6. shows a bottom view of the park lock system according to the embodiment of Fig. 3, with the gear wheel removed;

Fig. 7 shows a perspective top/side view an example of the lock gear part and the pressing block according to the invention mounted on the gear wheel;

Fig. 8 shows an exploded top/side view of the lock gear part, the pressing block and the gear wheel of Fig. 7;

Fig. 9 shows an exploded bottom/ side view of the lock gear part, the pressing block and the gear wheel of Fig. 7.

DETAILED DESCRIPTION OF THE FIGURES

In this application similar or corresponding features are denoted by similar or corresponding reference signs. The description of the various embodiments is not limited to the examples shown in the figures and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiments, but are included to elucidate the embodiments by referring to the example shown in the figures.

In the most general terms, the invention relates to a park lock system 10 for a vehicle driveline 12 comprising a gear wheel 14 that is coupled to a rotatable member of the driveline 12, the gear wheel

comprising a plurality of circumferentially spaced apart gear wheel teeth 16, which are aligned along a gear wheel teeth circle 18 having a gear wheel circle radius 20, and a lock gear part 22, comprising a plurality of spaced apart lock gear part teeth 24, wherein tips of the lock gear part teeth 24 are spaced apart at a lock gear part teeth pitch. The lock gear part 22 is moveably arranged along a first axis 26 so as to be moveable towards and away form the gear wheel 14. The lock gear part 22 has a lock position in which the lock gear part teeth 24 engage the gear wheel teeth 16 so that rotation of the gear wheel 14 is blocked, and the lock gear part 22 has a release position in which the lock gear part 22 is moved away from the gear wheel 14 so that the lock gear part teeth 24 are disengaged from the gear wheel teeth 16 so that the gear wheel 14 is rotatable. The lock gear part 22 is moveable arranged along a part of a circular line 30 having a radius 32 that is substantially equal to the gear wheel circle radius 20. The lock gear part 22 further comprises an alignment tooth 38 having a tip which is tangentially offset with respect to the lock gear part teeth tips. The alignment tooth 38 has a protruding position wherein the tip of the alignment tooth 38 is protruding beyond the tips of the lock gear part teeth 24 towards the gear wheel 14. It is clear that the above also covers embodiments in which the lock gear part 22 comprises more than one alignment tooth 38.

When a driver parks a vehicle, it is usually preferred that it does not move until the driver returns. If the vehicle is for instance on a slope, gravity will cause the vehicle wanting to move, causing the wheels to rotate and consequently the driveline 12 to rotate also. The idea of the park lock system 10 is to prevent this unwanted movement. The park lock system 10 operates by means of engagement of the lock gear part 22 with the gear wheel 14, or more specifically, by means of engagement of the lock gear part teeth 24 with the gear wheel teeth 16. The gear wheel 14 is part of or connected to the vehicle driveline 12. The driveline component for which the park lock system 10 is intended can be e.g. a differential assembly or a shaft assembly of the vehicle. In other words, the gear wheel 14 may be part of or can be connected to e.g. a differential assembly or a shaft assembly of the vehicle. But it is also possible to use other components of the vehicle driveline 12.

An advantage of the invention is that multiple teeth are used for engagement, resulting in less force or torque per teeth as opposed to using only one teeth or lug. Engagement of the teeth 16, 24 should of course preferably only been made when the vehicle is at a complete standstill. Only then will the gear wheel 14 not be rotating. Engaging the lock gear part teeth 24 with the gear wheel teeth 16 of a still rotating gear wheel 14 would risk damaging the park lock system 10 or even the vehicle driveline 12 all together.

When the lock gear part 22 is moved towards the gear wheel 14, the lock gear part teeth 24 and the gear wheel teeth 16 will engage. Only when the tips of the lock gear part teeth 24 are aligned exactly in the middle between the tips of the gear wheel teeth 16 , the lock gear part 22 can reach its lock position without the need for relative displacement in a tangential direction along the gear wheel teeth circle 18. When this alignment does not occur, which will be more often than not, the lock gear part teeth 24 and gear wheel teeth 16 engage before the lock gear part 22 reaches its lock position and thereby force the lock gear part 22 in a tangential position in which the tips of the lock gear part 22 are aligned exactly in the middle between the tips of the gear wheel teeth 16. By virtue of the tangentially movable lock gear part 22, the gear wheel 14 does not have to rotate. If the lock gear part 22 would not be tangentially movable, engagement of the lock gear part teeth 24 with the gear wheel teeth 16 would result in a rotation of the gear wheel 14. This rotation is not desirable, because this would mean a rotation of the vehicle driveline 12 and a movement of the vehicle.

Because the gear wheel 14 can stop in any given, arbitrary position, there is a chance that the tips of the lock gear part teeth 24 and gear wheel teeth 16 are aligned directly opposite to each other. In that case, moving the lock gear part 22 along the first axis 26 from the release position towards the gear wheel 16 would amount to pushing the tips of both set of teeth 16, 24 onto each other, making the engagement unstable. This may prevent that the lock gear part 22 reaches its lock position so that no park lock is achieved. Alternatively, one set of teeth 16, 24 may give way, resulting in a movement of either or both the gear wheel 16 and/or lock gear part 22 and consequently in a sudden and rapid movement of the lock gear part 22 towards its lock position accompanied with a resulting shock load. This would be an uncontrolled and unwanted movement, which could potentially be damaging for both the park lock system 10 and the vehicle driveline 12. The presence of the alignment tooth 38 counteracts this unwanted movement. This alignment tooth 38 protrudes beyond the tips of the lock gear part teeth 24 towards the gear wheel teeth 16. This protrusion can be e.g. about 1 to 5 mm, preferably about 2,25 mm.

The working of the alignment tooth 38 is as follows. There are three possibilities concerning the alignment of the lock gear part teeth 24 with respect to the gear wheel teeth 16.

The first possible alignment of the lock gear part teeth 24 with respect to the gear wheel teeth 16 is that the tips of the lock gear part teeth 24 are aligned with the middle of the spaces between gear wheel teeth 16. In this alignment the sets of teeth 16, 24 will engage and no use will be made of the alignment tooth 24, nor will the movement of the lock gear part 22 along the part of the circular line 30 be needed.

The second possible alignment of the lock gear part teeth 24 with respect to the gear wheel teeth 16 is that the tips of the lock gear part teeth 24 are neither aligned with the middle of the spaces between gear wheel teeth 16, nor are they aligned directly opposite to the tips of the gear wheel teeth 16. In this alignment the tips of the lock gear part teeth 24 will engage side faces of the gear wheel teeth 16, wherein this interaction will push the lock gear part 22 in a tangential direction along the part of the circular line 30. The third possible alignment of the lock gear part teeth 24 with respect to the gear wheel teeth 16 is that the tips of the lock gear part teeth 24 are aligned directly opposite to the tips of the gear wheel teeth 16. In this alignment, because the tip of the alignment tooth 38 is tangentially offset with respect to the tips of the lock gear part teeth 24, the tip of the alignment tooth 38 will not be directly opposite to a tip of one of the gear wheel teeth 16. During engagement of the lock gear part 22 and the gear wheel 14, the protruding alignment tooth 38 will make contact with one tooth of the gear wheel teeth 16, before the rest of the lock gear part teeth 24 will make contact with the gear wheel teeth 16. A side face of the tooth of the gear wheel teeth 16 will push the alignment tooth 38 in a tangential direction along the part of the circular line 30. In doing so it will also push the lock gear part 22 in that tangential direction along the part of the circular line 30. Therefore the interaction between the protruding alignment tooth 38 and the gear wheel teeth 24 will move the lock gear part 22 so that the tips of the sets of teeth 16, 24 will not be aligned directly opposite to each other anymore. When subsequently the lock gear part teeth 24 will engage with the gear wheel teeth 16. The lock gear part teeth 24 will engage side faces of the gear wheel teeth 16, wherein the interaction will push the lock gear part 22 even more along the tangential direction. The tangential movement of the lock gear part 22 along the part of the circular line 30 may, for example, be guided by the configuration of a lock gear part chamber 28 in which the lock gear part 22 may be mounted. The tangentially moveable lock gear part 22 and the alignment tooth 38 work together for a controlled engagement of the lock gear part 22 with the gear wheel 14. The alignment tooth 38 will bias the lock gear part 22 in a position beneficial for

engagement before the rest of the lock gear part teeth 24 engage with the gear wheel teeth 16.

The above described invention has several advantages. One advantage is, as mentioned before, that multiple teeth are used for engagement, resulting in less rotational force or torque per teeth as opposed to using only one teeth or lug. Another advantage is that the use of the alignment tooth allows for a controlled engagement of the lock gear part 22 with the gear wheel 14, irrespective of the position of the gear wheel 14 with respect to the lock gear part 22.

In an embodiment of the invention the lock gear part 22 is movable in two directions along the part of the circular line 30.

The movement of the lock gear part 22 is preferably in the direction which needs the least amount of travel to reach the needed alignment of the lock gear part teeth 24 and gear wheel teeth 16. When the lock gear part teeth 24 engage the gear wheel teeth 16, the lock gear part teeth 24 will engage side faces of the gear wheel teeth 16. Due to the arbitrary alignment of the gear wheel 14 with respect to the lock gear part 22, this engagement can be at one side face or at an other side face of the gear wheel teeth 16. This means that the gear wheel 14 can push the lock gear part 22 in one direction, when the lock gear part teeth 24 engage at one side face of the gear wheel teeth 16, or the gear wheel 14 can push the lock gear part 22 in an other direction, when the lock gear part teeth 24 engage at another side face of the gear wheel teeth 16.

In an embodiment of the invention the lock gear part 22 comprises an annular body, and the lock gear part teeth 24 are spaced apart along a full circle.

The lock gear part 22 may comprise a partial circle part or a full circle part or annular body. The movement of the lock gear part 22 along the part of the circular line 30 then amounts to rotating the lock gear part 22 along the part of the circular line 30. This rotation is around an axis, which preferably coincides with the first axis 26. An example of lock gear part 22 which comprises a partial circle part is shown in the example of figures 1-5. An example of lock gear part 22 which comprises a full circle part is shown in the example of figure 7-9. In an embodiment of the invention the park lock system 10 further comprises biasing means 34 which are configured for biasing the lock gear part 22 in an initial position and which allow movement of the lock gear part 22 along the part of the circular line 30.

These biasing means 34 urge the lock gear part 22 in the initial position. But when engagement of the lock gear part teeth 24 and gear wheel teeth 16 results in a movement of the lock gear part 22, the biasing means 34 will allow the movement of the tangentially moveable lock gear part 22 in a direction along the part of the circular line 30. This movement may be in two directions along the part of the circular line 30, preferably in the direction which, starting from the initial position, needs the least amount of travel to reach the needed alignment of the lock gear part teeth 24 and gear wheel teeth 16

In an embodiment of the invention the biasing means comprises at least one biasing spring 34 pushing the lock gear part 22 into the initial position, wherein the at least one biasing spring 34 allows the lock gear part 22 to move in a direction along the part of the circular line 30.

When the biasing means comprises at least one biasing spring 34 this at least one biasing spring 34 will center the lock gear part 22 in the initial position when the sets of teeth 16, 24 are not engaged. The spring constant of the at least one biasing spring 34 will have to be small enough so that the resulting spring force due to the deviation, or biasing, of the lock gear part 22 with respect to the initial, or rest, position, is smaller than the static, rotational friction of the gear wheel 14 and the thereupon coupled driveline 12. Only then will the gear wheel 14 push the lock gear part 22 sideways during engagement. The biasing spring 34 can be e.g. a leaf spring or a helical spring. In Figure 4 a leaf spring is shown in combination with a partial lock gear part 22 and in Figure 8 a helical spring is shown in combination with a full circle lock gear part 22. But these combinations are not limiting, it is also possible to use a leaf spring with a full circle lock gear part 22 and to use a helical spring with a partial lock gear part 22.

In an embodiment of the invention the alignment tooth 38 is movable with respect to the lock gear part teeth 24 in a direction

substantially parallel to the first axis 26. The alignment tooth 38 may be movable between an alignment position wherein the tip of the alignment tooth 38 is aligned with the tips of the lock gear part teeth 22 in an addendum plane 40 of the lock gear part teeth 24, and the protruding position.

Because the alignment tooth 38 protrudes beyond the other lock gear part teeth 24, it may be constructed bigger than the other lock gear part teeth 24. In order to enable a good engagement between the lock gear part teeth 24 and the gear wheel teeth 16, this extra size has to be accounted for. This can for instance be done by making a height of the lock gear part teeth 24 smaller than a height of gaps between the gear wheel teeth 16 in such a way that also the bigger alignment tooth 38 will fit in the gap between two gear wheel teeth 16. Another solution is to make the alignment tooth 38 moveable with respect to the lock gear part teeth 24 in a direction substantially parallel to the first axis 26. In that way the tip of the alignment tooth 38 can be aligned with the tips op the lock gear part teeth 22 in the addendum plane 40 during engagement of the two sets of teeth 16, 24, the alignment tooth 38 thus not having any extra height to be accounted for.

In a further embodiment of the invention the park lock system 10 may further comprise an alignment tooth spring 42 which pushes the alignment tooth 38 into the protruding position. The alignment tooth spring 42 may be provided in the lock gear part 22.

When the lock gear part 22 is in the release position the alignment tooth spring 42 pushes the alignment tooth 38 into the protruding position. During engagement of the lock gear part 22 with the gear wheel 14, the gear wheel 14 will push the protruding alignment tooth 38 against the push of the alignment tooth spring 42 into the alignment position. The spring constant of the alignment tooth spring 42 should be chosen carefully. It should be high enough to let the gear wheel teeth 16 push the alignment tooth 38 and thus the entire lock gear part 22 in the tangential direction along the part of the circular line 30 during engagement of the lock gear part 22 with the gear wheel 14. On the other hand, the spring constant should be low enough that the alignment tooth 38 will be pushed inwardly during engagement of the lock gear part 22 with the gear wheel 16, and not exert unwanted forces on the gear wheel 16 resulting in a unwanted rotation of the latter. When using at least one biasing spring 34 as biasing means, the spring constant of the alignment tooth spring 42 and the spring constant of the at least one biasing spring 34 will have to be balanced with the static, rotation friction of the lock gear 22.

In an embodiment of the invention the alignment tooth 38 has a profile different from the profile of the rest of the lock gear part teeth 24. This may be e.g. a non-symmetrical profile.

In order for the tip of the alignment tooth 38 to be offset in the tangential direction with respect to the tips of the lock gear part teeth, the alignment tooth 38 could have exactly the same configuration as the lock gear part teeth 24, but simply be tangentially offset. Another possibility for the alignment tooth 38, in order for the tip of the alignment tooth 38 to be offset with respect to the tips of the lock gear part teeth, is to have an alignment tooth with a profile different from the profile of the lock gear part teeth 24. This may be e.g. a non-symmetrical profile. In this way the gaps on either side of the alignment tooth 38 can remain substantially the same, making engagement with the gear wheel teeth 16 less complicated.

In an embodiment of the invention, the park lock system 10 may further comprise an actuator assembly 46 which, when actuated, pushes the lock gear part 22 into the lock position. In a further elaboration of that embodiment, the actuator assembly 46 may comprise a pressing block 51 of which an outer surface pushes directly on an outer surface of the lock gear part 22, a self-locking

trapezoidal spindle 48, and an actuator 50 connected to the self-locking trapezoidal spindle 48. The actuator 50 may be configured to rotate the self locking trapezoidal spindle 48. The self-locking trapezoidal spindle 48 is rotatably connected with a trapezoidal treaded hole in the pressing block 51. When the self-locking trapezoidal spindle 48 rotates in a first direction it pushes the pressing block 51 towards and onto the lock gear part 22, so that the pressing block 51 pushes the lock gear part 22 from the release position to the lock position. When the trapezoidal spindle 48 rotates in a direction opposite the first direction, it pulls the pressing block 51 away from the lock gear part 22.

The pressing block 51 may, for example, engage an outer surface of the lock gear part 22 that is opposite the lock gear part teeth 24. In the lock position, the pressing block 51 pushes against the lock gear part 22.

By using a self-locking trapezoidal spindle 48 axial forces exerted on the spindle 48 by the pressing block 51, will not result in rotation of the spindle. This means that the actuator can be used to rotate the spindle 48, and thus translate the pressing block 51 into a desired position, at which position the pressing block 51 will remain without needing the actuator 50 to exert force on the spindle. Only when the actuator 50 rotates the self locking trapezoidal spindle 48 this will result in a translation of the pressing block 51 in a direction along the first axis 26.

The pressing block 51 is not moveable in a direction parallel to the circular line 30, whereas the lock gear part 22 is moveable along the circular line 30. This means that, when the pressing block 51 not moveable in a direction parallel to the circular line 30, the lock gear part 22 needs to be able to move with respect to the pressing block 51 in that direction. This can, for instance, be done by arranging the lock gear part 22 to slide against the pressing block 51. This of course means that the biasing means 34 will have to allow the lock gear part 22 to slide against the pressing block 51. This also means that the biasing means 34 must be strong enough to overcome friction between the lock gear part 22 and the pressing block 51 when the lock gear part 22 has not yet reached the lock position.

Of course the actuator assembly 46 must only push the lock gear part 22 into the lock position, when the vehicle is at a standstill. Only then will the vehicle driveline 12 and thus the gear wheel 14 be standing still, making engagement of the lock gear part teeth 24 and gear wheel teeth 16 possible without risking damage to the park lock system 10. This can be implemented electronically by making sure the actuator only makes the sets of teeth 16, 24 engage at a standstill of the vehicle driveline 12. In an automatic gearing vehicle which is equipped with a shift by wire system, this can be easily implemented since the rotation of the driveline is already electronically measured and known.

In a further elaboration of the actuator assembly it may comprise at least one pull spring 44 pulling the lock gear part 22 in the direction of the release position.

In this embodiment, the movement of the lock gear part 22 along the first axis 26 is possible by collaboration of the pull spring 44 and the actuator assembly 46. The former pulling the lock gear part 22 into the release position, the latter pushing the lock gear part 22 into the lock position. It is of course also possible to devise the actuator assembly 46 such that it can also pull the lock gear part 22 into the release position, rendering the pull spring 44 superfluous.

In an embodiment of the invention the at least one pull spring 44 also constitutes the biasing means which are configured for biasing the lock gear part 22 in an initial position and which allow movement of the lock gear part 22 along the part of the circular line 30. Combining multiple functions of the park lock system 10 within a single part, provides a simple and elegant design. Less parts means the park lock system 10 will be easier and cheaper to build.

In an embodiment of the invention the lock gear part teeth 24 are rounded off and/or are chamfered.

In order to facilitate the engagement between the lock gear part teeth 24 and the gear wheel teeth 16 the profile of the lock gear part teeth 24 can be adapted. The same applies of course also to the gear wheel teeth 16.

In an embodiment of the invention the lock gear part 22 may be mounted in a lock gear part chamber 28 bounded by a lock gear part housing 54. This lock gear part housing 54 may be integral to a clutch or transmission housing 56 of a vehicle.

The park lock system 10 can be implemented as a device with its own lock gear part housing 54. This housing can than be mounted upon any suitable position near the vehicle driveline 12 so that the lock gear part 22 can engage the gear wheel 14. The park lock system 10 can also be

implemented as a device without its own separate lock gear part housing 54, but instead be placed within and be made part of a clutch or transmission housing 56 of a vehicle.

In a further elaboration of this embodiment of the invention, the movement of the lock gear part 22 along the part of the circular line 30 may be limited by a wall of the lock gear part housing 54.

When the lock gear part 22 and the gear wheel 14 are engaged, the lock gear part 22 prevents movement of the gear wheel 14. In this

embodiment the movement of the lock gear part 22 is bounded by a wall of the lock gear part housing 54. This means that the gear wheel 14 can move the lock gear part 22 until the lock gear part 22 hits the wall of the lock gear part housing 54. Further movement is than not possible. Another option to prevent movement of the lock gear part 22 is shown in the example of figures 7-9. There the lock gear part 22 is provided with cams 58 which are each positioned in an associated cam chamber 60 in the pressing block 51. In that example, the helical biasing springs 34 are engaging the cams 58 and the side walls of the cam chambers 60.

Another aspect of the invention provides a vehicle, comprising a park lock system 10 according to the invention.

The various embodiments which are described above may be used implemented independently from one another and may be combined with one another in various ways. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments nor do they limit the claims. The reference numbers are solely used to clarify.

Legend

10 - park lock system

12 - vehicle driveline

14 - gear wheel

16 - gear wheel teeth

18 - gear wheel teeth circle

20 - gear wheel circle radius

22 - lock gear part

24 - lock gear part teeth

26 - first axis

28 - lock gear part chamber

30— circular line

32 - radius (of the circular line)

34 - biasing spring

38 - alignment tooth

40 - addendum plane (of the lock gear part teeth) 42 - alignment tooth spring

44— pull spring

46 - actuator assembly

48 - self-locking trapezoidal spindle

50 - actuator

51 - pressing block

54— lock gear part housing

56 - transmission housing

58 - cam

60— cam chamber

Claims

1. A park lock system (10) for a vehicle driveline (12), comprising:

a gear wheel (14) that is coupled to a rotatable member of the driveline (12), the gear wheel comprising a plurality of circumferentially spaced apart gear wheel teeth (16), which are aligned along a gear wheel teeth circle (18) having a gear wheel circle radius (20); and

a lock gear part (22), comprising a plurality of spaced apart lock gear part teeth (24), wherein tips of the lock gear part teeth (24) are spaced apart at a lock gear part teeth pitch,

wherein the lock gear part (22) is moveably arranged along a first axis (26) so as to be moveable towards and away form the gear wheel (14), wherein the lock gear part (22) has a lock position in which the lock gear part teeth (24) engage the gear wheel teeth (16) so that rotation of the gear wheel (14) is blocked,

wherein the lock gear part (22) has a release position in which the lock gear part (22) is moved away from the gear wheel (14) so that the lock gear part teeth (24) are disengaged from the gear wheel teeth (16) so that the gear wheel (14) is rotatable,

wherein the lock gear part (22) is moveable arranged along a part of a circular line (30) having a radius (32) that is substantially equal to the gear wheel circle radius (20),

wherein the lock gear part (22) further comprises an alignment tooth (38) having a tip which is tangentially offset of with respect to lock gear part teeth tips, and

wherein the alignment tooth (38) has a protruding position wherein the tip of the alignment tooth (38) is protruding beyond the tips of the lock gear part teeth (24) towards the gear wheel (14).

2. The park lock system according claim 1, wherein the lock gear part (22) is movable in two directions along the part of the circular line (30).

3. The park lock system according to claim 1 or 2, wherein the lock gear part (22) comprises an annular body, and wherein the lock gear part teeth (24) are spaced apart along a full circle.

4. The park lock system according to any one of the previous claims, further comprising biasing means (34) which are configured for biasing the lock gear part (22) in an initial position and which allow movement of the lock gear part (22) along the part of the circular line (30).

5. The park lock system according to claim 4, wherein the biasing means (34) comprises at least one biasing spring (34) pushing the lock gear part (22) into the initial position, and wherein the at least one biasing spring (34) allows the lock gear part (22) to move in a direction along the part of the circular line (30).

6. The park lock system according any one of the previous claims, wherein the alignment tooth (38) is movable with respect to the lock gear part teeth (24) in a direction substantially parallel to the first axis (26).

7. The park lock system according to claim 6, wherein the alignment tooth (38) is movable between an alignment position wherein the tip of the alignment tooth (38) is aligned with the tips of the lock gear part teeth (22) in an addendum plane (40) of the lock gear part teeth (24), and the protruding position.

8. The park lock system according to claim 7, wherein the park lock system (10) further comprises an alignment tooth spring (42) which pushes the alignment tooth (38) into the protruding position.

9. The park lock system according to claim 8, wherein the alignment tooth spring (42) is provided in the lock gear part (22).

10. The park lock system according to any one of the previous claims, wherein the alignment tooth (38) has a profile different from the profile of the lock gear part teeth (24).

11. The park lock system according to any one of the previous claims, wherein the alignment tooth (38) has a non- symmetrical profile.

12. The park lock system according to any one of the previous claims, further comprising:

an actuator assembly (46) which, when actuated, pushes the lock gear part (22) into the lock position.

13. The park lock system according to claim 12, wherein the actuator assembly (46) comprises:

a pressing block (51) of which an outer surface pushes directly on an outer surface of the lock gear part (22);

a self-locking trapezoidal spindle (48);

- an actuator (50) connected to the self-locking trapezoidal spindle

(48) and configured to rotate the self-locking trapezoidal spindle (48);

wherein the self-locking trapezoidal spindle (48) is rotatably connected with a trapezoidal treaded hole in the pressing block (51),

wherein the self-locking trapezoidal spindle (48) rotating in a first direction pushes the pressing block (51) towards and onto the lock gear part (22), so that the pressing block (51) pushes the lock gear part (22) from the release position to the lock position, and

wherein the trapezoidal spindle (48) rotating in a direction opposite the first direction pulls the pressing block (51) away from the lock gear part (22).

14. The park lock system according to claim 12 or 13, wherein the actuator assembly comprises:

at least one pull spring (44) pulling the lock gear part (22) in the direction of the release position.

15. The park lock system according to claim 14, and at least dependent on claim 4, wherein the at least one pull spring (44) also constitutes the biasing means which are configured for biasing the lock gear part (22) in an initial position and which allow movement of the lock gear part (22) along the part of the circular line (30).

16. The park lock system according to any one of the previous claims, wherein the lock gear part teeth (24) are rounded off.

17. The park lock system according to any one of the previous claims, wherein the lock gear part teeth (24) are chamfered.

18. The park lock system according to any one of the previous claims, wherein the lock gear part (22) is mounted in a lock gear part chamber (28) bounded by a lock gear part housing (54).

19. The park lock system according to claim 18, wherein the movement of the lock gear part (22) along the part of the circular line (30) is limited by a wall of the lock gear part housing (54).

20. The park lock system according to claim 18 or 19, wherein the lock gear part housing (54) is integral to a clutch or transmission housing (56) of a vehicle.

21. A vehicle, comprising a park lock system (10) according to any one of the previous claims.