FR3059386A1 - MOTOR VEHICLE WHEEL BLOCK SYSTEM INCORPORATING A PARKING LOCK FUNCTION - Google Patents

Abstract

A crimped wheel locking system (100) comprising a locking finger (200, 250) rotatably hinged to a housing, and an actuating means (300, 350, 211, 231, 261), the finger being, when the system is controlled to engage a locking position, introduced by the actuating means into a slot of the wheel and forced against it by a feedback, the actuating means comprising a movable roller holder (300) in rotation with respect to the casing, acting on the finger, to evolve towards the locking position via a first roller (211, 261), the counter-reaction being provided by a second roller (211, 261) of the d actuation.

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

LOCKING SYSTEM FOR SLOTTED WHEEL FOR A MOTOR VEHICLE INCORPORATING A PARKING LOCK FUNCTION.

FR 3 059 386 - A1 (5 /) Locking system for castellated wheel (100) comprising a locking finger (200, 250) articulated in rotation on a casing, and an actuating means (300, 350, 211, 231, 261), the finger being, when the system is controlled to engage a locking position, introduced by the actuating means into a slot of the wheel and constrained against the latter by a feedback, the means of actuation comprising a roller carrier (300) movable in rotation relative to the casing, acting on the finger, to move towards the locking position by means of a first roller (211, 261), the counter-reaction being provided by a second roller (211,261) of the actuating means.

LOCKING SYSTEM FOR SLOTTED WHEEL FOR A MOTOR VEHICLE INCORPORATING A PARKING LOCK FUNCTION The invention relates to the field of traction power transmission for a motor vehicle, and relates to a locking system in the stationary position of the transmission components, for parking the vehicle, including on a sloping area.

We know parking locks used to block the drive shafts by intervening at the gearbox. They are used when the vehicle is parked. The gearboxes concerned are automatic gearboxes or robotised double clutch gearboxes on vehicles with thermal engines. Gearboxes for electrically powered vehicles can also be fitted with similar parking locks. The parking lock is an internal control of the gearbox or gearbox.

Parking locks generally use a single locking finger, actuated when the driver engages the gearshift lever in position P, for parking. The actuation is carried out by means of a spring-loaded roller carriage system making it possible, by pressing against a reinforced zone of the gearbox casing or of the reduction gear, to constrain the locking finger in a slot of a castellated wheel fixedly mounted on a drive shaft.

The carriage comprises rollers interposed between the finger and the gearbox housing. These rollers reduce friction between the finger and the carriage, and between the carriage and the casing during the transition between the locked position and the unlocked position. On the other hand they are used, in the locking position, to transmit resistance or feedback, from the housing to the finger, preventing the latter from leaving the slot despite a possible force imposed on the shaft and the wheel to niche. The feedback is transmitted by crushing one roller on the other, between the finger and the housing.

FR2967226 describes a parking lock system using such a carriage with two rollers, controlled in translation.

We are faced with the problem of finding alternatives to existing devices, which are reliable in the face of the large forces which may appear on the shaft and the toothed wheel, which have different control kinematics, and which can be used with flexibility. , especially in terms of space.

For this, a blocking system is proposed for a castellated wheel, comprising a blocking finger articulated around an axis of rotation of the finger on a casing of the system, and an actuation means, the finger being, when the system is controlled to engage a locking position, introduced by the actuating means into a wheel slot and constrained against said wheel by a feedback opposing rotational forces on the wheel, the means d actuation comprising a roller carrier movable relative to the casing, acting on the finger, to make it switch from the unlocking position to the locking position, by means of a first rolling roller carried by the roller carrier , arranged parallel to the axis of rotation of the finger and rolling on a cam of the finger, the feedback being provided by means of the first roller and a second rolling roller carried by the roller holder s parallel to the first roller and pressing, in the locking position, on the first roller to transmit the feedback, the second roller rolling on a piece of feedback providing, in the locking position, the feedback, the first and second rollers being coupled with one another in rotation, so as to facilitate the passage from the unlocking position to the locking position.

The system is remarkable in that the roller carrier is movable relative to the housing in rotation about an axis of rotation of the roller carrier parallel to the axis of rotation of the finger, the first and second rollers being arranged symmetrically with respect to the axis of rotation of the roller carrier and the cam and the feedback part respectively supplying the first and second rollers, when approaching the locking position, forces having a symmetry axial around the axis of rotation of the roller holder, and an intermediate roller being mounted around said axis of rotation of the roller holder so that the second roller presses, in the locked position, on the first roller via of the intermediate roller and that the first and second rollers are coupled with each other in rotation so that a rotation of the first roller causes a rotation of the second roller in the same direction.

The activation of the system to the locking position being done by rotation, it is first of all possible to place the mechanism in gearboxes or reducers having a constrained geometry not allowing to install a control in translation. In addition, it is possible to propose several multiplications of the control action by varying the length of a lever used to control the rotation. There is therefore flexibility in the implementation and handling of the system.

Optional features can be envisaged, and offer advantages as follows:

- The first and second rollers are arranged between two parallel flat flanges constituting a body of the roller holder;

- The actuating means comprises a lever and a spring for changing the roller carrier from the unlocking position to the locking position by damping any resistance to the engagement of the locking fingers in the slots of the wheel;

- said finger being a first finger, the feedback part is a second locking finger of the transmission system articulated in rotation on the casing of the transmission system around an axis of rotation of the second parallel or coincident finger with the axis of rotation of the first finger; This makes it possible to reduce the stresses on the castellated wheel which makes it possible to reduce the size of the parts; This also eliminates the machining constraints of the gearbox casings;

- the first and second fingers are symmetrical to one another with respect to a plane of symmetry of the shaft, the axis of rotation) of the roller carrier being included in said plane of symmetry;

- the first finger is articulated in rotation with respect to the casing around the axis of rotation of the second finger which constitutes an axis of rotation common to the two fingers;

- The system comprises a pin spring mounted on the common axis of rotation for, when the transmission system is controlled to release the transmission, move the locking fingers apart from each other so as to move them apart of the wheel;

- The first and the second locking finger have shapes which are respectively complementary to diametrically opposite slots of the wheel.

The invention also relates to a traction power transmission system comprising a power transmission shaft, a notched wheel fixedly mounted on said shaft and a notched wheel locking system as presented above for, by acting on the stepped wheel, lock or unlock the power transmission system.

The invention also relates to a motor vehicle comprising a traction power transmission system according to the invention and comprising a parking lock control controlling the evolution of the system from the locking position to the unlocking position in acting on the actuating means.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, made with reference to the appended drawings given solely by way of example illustrating a embodiment of the invention and in which:

- Figure 1 is a view of an embodiment prior to the invention;

- Figures 2 and 3 are views of an embodiment of the invention in a configuration in which the transmission is free (unlocking position);

- Figures 4 and 5 are views of the same embodiment of the invention in a configuration in which the transmission is being blocked;

- Figures 6 and 7 are views of the same embodiment of the invention in a configuration in which the transmission is blocked for parking (locked position).

Figure 1 shows a parking lock device prior to the invention. This is part of a traction power transmission system for a motor vehicle.

A square wheel 10 is shown. It carries on its circumference a regular succession of teeth and slots. It is mounted on a traction power transmission shaft, for example a secondary gearbox shaft (not shown). A locking finger 20 is articulated in rotation with respect to the mechanism casing, here the gearbox casing (not shown), via an axis 25 parallel to the transmission shaft. The locking finger 20 comprises a lug 21 which is dimensioned to be introduced into a crenel of the wheel 10. The lug 21 is positioned between the center of the wheel 10 and a resistance piece 40 secured and fixed vis-à-vis of the casing, on the face of the finger 20 facing the rouelO. A part 45 enables the resistance part and the pin 25 to be fixed to the mechanism housing.

A roller carrier carriage 30 is mounted movable in translation with respect to the casing, and is maneuvered using a spring rod 35. The carriage 30 moves in the space between the resistance part 40 and the face of the finger 20 opposite the lug 21, between two positions, one remote from the axis 25 corresponding to an unlocking of the parking lock, and the other closer to the axis 25 and corresponding to the locking.

During its movement from the unlocking position to the locking position, the carriage exerts a cam effect on the finger, by means of its face opposite the lug 21, causing the finger to pivot on the axis 25 and the lug to be inserted in a slot of the wheel 10. Two rollers (not shown) fixed in translation with respect to the carriage 30 facilitate this movement, for example one in contact with the resistance piece 40 and the other in contact with the finger 20.

Once in the locked position, the carriage 30 transmits a force from the wheel and the finger to the resistance piece 40, and the latter is opposed, by means of the rollers which press one on the other at the exit of the pin of the slot, even in the event of a strong effort on the drive shaft, for example when the vehicle is parked on a slope.

A pin spring 27 is disposed on the finger 30, around the axis 25, to exert a restoring force and keep the finger away from the wheel 10 once the finger released by the reverse movement of the carriage 30 , from the locking position to the unlocking position.

The carriage 30, the spring rod 35 and the rollers constitute an actuating means for the transmission system and more specifically for the parking lock device. The control of the transmission system is likely to set in motion this actuating means to release the transmission to allow the vehicle to set in motion or, on the contrary, engage a locking position corresponding to the parking lock.

Figures 2 and 3 show an embodiment of the invention, in a configuration in which the transmission is unlocked. The same device is shown in Figures 4 and 5 in a configuration in which the transmission is being blocked, and Figures 6 and 7 show a configuration in which the transmission is blocked.

A stepped wheel 100 is shown. It again bears on its circumference a regular succession of teeth and slots. It is always mounted on a power transmission shaft, for example a secondary gearbox shaft (not shown). A first locking finger 200 is articulated in rotation with respect to the mechanism housing, here the gearbox housing (not shown), via an axis 205 parallel to the transmission shaft. The locking finger 200 comprises a lug 201 which is dimensioned to be introduced into a slot of the wheel 100. A second locking finger 250 is articulated in rotation with respect to the casing, via in the present embodiment the same axis 205 as the first finger 200. The locking finger 250 comprises a lug 251 which is dimensioned to be introduced into a slot in the wheel 100. The first finger 200 and the second finger 250 respectively comprise a branch 210 and a branch 260 which are placed so that, when the lugs 201 and 251 move away from one another by relative rotation of the fingers 200 and 250 around the common axis 205, move towards one another. More precisely, the shape retained for each of the fingers to obtain this effect is that of a triangle between the lug 201 (respectively 251), the axis 205 and the distal part of the branch 210 (respectively 260), with an angle obtuse at the level of the axis 205, the distal part of the branch 210 (respectively 260) being in the same half-space with respect to the plane consisting of the axis of the transmission shaft and the axis 205 as the lug 201 (respectively 261), the fingers 200 and 250 being able to be installed symmetrically with respect to said plane and the distal parts of the branches 210 and 260 then forming a jaw around said plane of symmetry which s' opens when the lugs 201 and 251 approach each other and closes when they move away from each other. In addition, the fingers 200 and 250 are dimensioned so that the lugs 201 and 251 cooperate with the wheel 100 by fitting into slots diametrically opposite from the latter.

A roller holder 300 is mounted movable in rotation vis-à-vis the housing, and is operated using a spring lever 350. It is movable in rotation about an axis 354 coplanar and parallel with the axis of the driveshaft and the axis 205, mounted on the housing. The roller carrier 300 consists of a roller carrier body and the rollers 211 and 261. The roller carrier body has a straight cylindrical shape whose base end is parallel to the plane orthogonal to the shaft transmission and its axis of rotation 354, and has a generally oblong shape. It consists of two plane flanges parallel to each other between which the rollers 211 and 261 are mounted, perpendicular to the plane of the flanges. The flanges are also perpendicular to the axis 354.

The axis 354 carries an intermediate roller 231 on its periphery, mounted perpendicular to the flanges and which is in contact with the rollers 211 and 261. The intermediate roller 231 constitutes a single intermediate roller.

The mechanism is oiled, and friction is limited.

The intermediate roller 231 is nevertheless driven in movement by the roller 211 by friction (friction) and transmits the drive received to the roller 261. Conversely, the intermediate roller 231 is also driven in movement by friction (friction) by the roller 261 and transmits the drive received to the roller 211. These movements are such that a roller 211 or 261 is not blocked, since it is coupled in rotation with the roller 211 or 261 opposite. The rollers 211 and 261 rotate in the same direction, and the roller 231 rotates in the opposite direction.

The roller carrier 300 follows a rotational movement in the space between the branch 210 and the branch 260, between two arrangements, one in which the direction of its length is distant from the axis 205 corresponding to a locking the parking lock (Figures 6 and 7), and the other in which the direction of its length is closer to the axis 25 and corresponding to the unlocking (Figures 2 and 3).

More specifically, in the embodiment presented, the roller holder 300 admits its axis of rotation 354 as an axis of symmetry, and in its arrangement in which the direction of its length is distant from the axis 205, its two ends in the direction of its length define with axis 205 an equilateral triangle.

In the embodiment shown, the axis 354 is fixed relative to the casing of the transmission system.

Each of the locking fingers 200 and 250 is articulated in rotation about an axis parallel to the transmission shaft (here a single axis which is the axis 205), and the roller holder 300 does not movement parallel to the shaft 100 between the locked position and the unlocked position. Thus, there is a compact mechanism, limited to a short section of the drive shaft on which the parking lock is brought to act.

During its movement from the unlocking position (Figures 2 and 3) to the locking position (Figures 6 and 7), the roller holder 300 exerts a cam effect (respectively a first and a second cam effect ) on the fingers 200 and 250, by means of protuberances carried by their branches 210 and 260 constituting cams 210a and 260a. The cam effects cause the locking fingers 200 and 250 to pivot around the axis 205 and the lugs 201 and 251 to seek to fit into a slot in the wheel 100.

The rollers 211 and 261 parallel to each other and fixed in translation with respect to the body of the roller holder 300 facilitate this movement by allowing rolling of the elements in contact, one at contact of the cam 210a of the branch 210 and the other in contact with the cam 260a of the branch 260.

The branches 210 and 260 have rolling surfaces on the cams 210a and 260a in contact with the roller carrier 300 which facilitate the first and second cam effects simultaneously on each of the fingers. In the case of a roller carrier which admits as its axis of symmetry its axis of rotation 354, the surfaces of the branches 210 and 260 in contact with the roller carrier 300 and the cams 210a and 260a tend to admit, in the direction of the position locking, the axis 354 as the axis of symmetry, which facilitates the simultaneous cam effects on each of the fingers, symmetrically around the axis of rotation.

Once in the locked position, the rollers 211, 231 and 261 transmit a force from the wheel and from the finger 200 to the finger 250, and this force is opposed, by means of the rollers 211, 231 and 261 at the outlet of the lug 201 of the slot in which it is inserted, even in the event of strong force on the drive shaft, for example when the vehicle is parked on a slope. Simultaneously, the rollers 211, 231 and 261 transmit a force from the wheel and from the finger 250 to the finger 200, and this force is opposed, via the rollers 211, 231 and 261 to the output of the lug 251 of the slot in which it is inserted, even in the event of strong force on the drive shaft. Since the transmitted forces can be significant in view of the resistance of the parts, it is useful for the cams 210a and 260a to have perfect or almost perfect symmetry in relation to the axis of rotation 354 near the locking position. that if this symmetry is not respected, or if a roller gets stuck (which requires an asymmetry of the efforts), the resulting effort is collected by the axis 354. But the risk of jamming is limited by the fact that the rollers 211 and 261 are coupled in rotation via the intermediate roller 231.

Thus, the first and second locking fingers 200 and 250 are forced against the wheel 100 by a first and a second feedback against opposing rotational forces on the shaft, provided by (or via) respectively the second and the first locking fingers 200, 250 by means of a movable element, in this case the rollers 211 and 261 of the roller holder 300, acting on the locking fingers 200 and 250 by cam effect to move them from the unlocked position to the locked position.

The roller carrier 300 and the lever 350 constitute an actuating means for the transmission system and more specifically for the parking lock device. As mentioned in relation to the prior system, the control of the transmission system is capable of setting in motion this actuating means to release the transmission to allow the vehicle to set in motion or on the contrary engage a locking position corresponding to the locking bolt car park.

In the system locking position, the locking fingers 200 and 250 are each constrained against the wheel 100 by a first and a second counter-reactions opposing rotational forces on the shaft, provided by respectively l 'other locking finger via the rollers. More precisely, the forces are transmitted from one finger to the roller (211 or 261) with which it is in contact, then to the intermediate roller 231, then to the other roller (211 and 261) and to the other finger, the elements pressing on each other on a plane of efforts extending from one finger to the other, between a flange of the roller holder to the other flange, and passing through the central axes of the three rollers and of the axis 354.

The lever 350 is, in the embodiment shown, essentially a flat plate carrying a pin spring 351 and articulated in rotation with respect to the casing around the axis 354. The plane of the lever 350 is positioned perpendicular to the axes of the two rollers 211 and 261. It is connected to the body of the roller holder 300 by a finger 302 projecting from a lateral flange thereof. The finger 302 is inserted into a hole made in the material of the plate of the lever 350, which ends with stops 355 and 353. The pin spring 351 is placed between the finger 302 on which it is supported on the side of the stop 353 and a grip on the lever 350. It exerts a restoring force to bring the lever 350 and the roller carrier 300 into rotation, around the axis 354.

From the unlocking position of the system (Figures 2 and 3), an action on the lever 350 in rotation in a positive direction chosen by convention causes a drive of the spring 351 by the lever 350 on which it is engaged , the spring 351 possibly storing energy, then the support of the spring 351 on the finger 302.

Pressing on finger 302 more or less rapidly causes the movement of the roller carrier 300. The displacement of the roller carrier 300 immediately involves the displacement of the rollers 211 and 261 which force the opening of the jaw formed by the branches 210 and 260 of fingers 200 and 250.

More specifically, in the absence of resistance to the insertion of the lugs 201 and 251 in slots of the wheel 100, the roller holder 300 immediately moves and immediately rotates the locking fingers, without the energy stored in the pin spring 351 is strong.

Conversely, if there is resistance to the insertion of the lugs 201 and 251 into slots of the wheel 100, the roller carrier 300 moves more slowly, energy being temporarily stored in the pin spring 351. The rotational adjustment of the power transmission shaft finally allows the pins to fit into a slot and to release the stored energy.

From the locked position of the system (Figures 6 and 7), an action in rotation in opposite direction (negative direction) on the lever 350 causes the displacement of the roller carriers 300 by pressing the stop 355 on the finger 302. The displacement of the rollers 211 and 261 immediately authorizes the closing of the jaw formed by the branches 210 and 260 of the fingers 200 and 250. This is favored by a pin spring 207.

And a pin spring 207 placed around the axis 205 and attached to both the finger 200 and the finger 205 tends to separate the lugs 201 and 251 from each other and to bring the branches 210 and 260 from one another by exerting a restoring force which keeps the fingers 201 and 251 away from the wheel 100 once the fingers are released by the movement of the roller carrier 300, from the locking position to the position of unlocking. The jaw closes around the axis 354.

As can be seen in Figures 2 and 3, the rotational travel of the roller carrier 300 between its two arrangements is long enough that the jaw exceeds the rollers 211 and 261 and closes only on the axis 354. In addition, the axis 354 has a sufficiently small diameter to allow the lugs 201 and 251 to be released from the wheel 100.

Alternatively, there could be additional intermediate rollers between the intermediate roller 231 and the rollers 211 and 261, in an even total number, so that with the intermediate roller 231 and the rollers 211 and 261, the number of rollers arranged in series is odd. These rollers, excluding the end rollers 211 and 261 constitute a system of intermediate rolling rollers having an axial symmetry about the axis. The end rollers 211 and 261, although coupled in rotation with each other, rotate in the same direction, thanks to the system of intermediate rollers.

Alternatively, the two locking fingers 200 and 250 can be articulated in rotation around two separate axes, both parallel to the transmission shaft.

In general, the two fingers can be identical and interchangeable, but they can also be different. Each finger forms a feedback piece for the other finger.

According to an alternative, the directions of movement of the lever 350 for unlocking and locking can be interchanged. In this case, cams 210a and 210b should be adapted if necessary. They are already adapted in the embodiment presented in the figures.

The invention extends to a single finger system, using a first roller for the action by cam effect on the finger, by the roller holder, and a second roller for interaction with a second part. of the mechanism resting on the casing, and providing a feedback (called a feedback piece).

The feedback part can be, as we have seen, a second finger blocking the shaft and placed in opposition with the first, the roller carrier being movable in strict rotation as we have seen. The feedback is then provided, both by the housing via the axis on which the second finger is mounted in rotation, that is to say here the axis 205, and by the toothed wheel. 100 (and therefore the power transmission shaft) which forces the second finger against the rollers. The feedback is provided by means of a moving part, namely the second finger, but retained by the axis 205 and therefore the casing, and also by the toothed wheel 100.

The feedback piece, carrying the cam which opposes the locking finger, can be a resistance piece of the system, fixed with respect to the casing, for example a resistance sheet fixed to the casing to resist forces on the drive shaft in the locked position. The roller carrier is movable in rotation about an axis with respect to the casing and the first and second rolling rollers are always arranged symmetrically around the axis and are coupled in rotation one with the another by means of an intermediate roller mounted on the axis, the forces being exerted symmetrically with respect to said axis, according to an axial symmetry. For this, the resistance piece is a cylindrical surface resistance sheet, constituting a fraction of a cylinder of revolution with an axis coincident with the axis of rotation of the roller carrier. The cylindrical surface offers the forces exerted, with those provided by the finger cam, symmetrically with respect to the axis on the rollers of the roller holder. The finger can be articulated with respect to the casing as in FIG. 1, for example. The feedback is provided by the casing, without mobile intermediary like a second finger.

The invention is implemented in a motor vehicle comprising a traction power transmission system and comprising a parking lock control controlling the evolution of this system from the locking position to the unlocking position and acting on lever 350. This can be modified so as to modify the reduction in the control action. This can be done by changing the length of the lever.

Claims (10)

1. Locking system for a stepped wheel (100), comprising a locking finger (200, 250) articulated around an axis of rotation of the finger (205) on a casing of the system, and an actuating means ( 300, 350, 211, 231, 261), the finger (200, 250) being, when the system is controlled to engage a locking position, introduced by the actuating means (300, 350, 211, 231, 261) in a wheel slot (100) and constrained against said wheel (100) by a counteraction opposing rotational forces on the wheel, the actuating means (300, 350, 211, 231, 261) comprising a roller carrier (300) movable relative to the housing, acting on the finger (200, 250), to cause it to switch from the unlocking position to the locking position, by means of a first roller (211 , 261) carried by the roller carrier (300), disposed parallel to the axis of rotation of the finger (205) and rolling on a cam (210a, 260a) of the doi gt (200, 250), the feedback being supplied to the finger via the first roller (211, 261) and a second roller (211,261) carried by the roller holder (300) parallel to the first roller (211, 261) and pressing, in the locked position, on the first roller (211, 261) to transmit the feedback, the second roller (211,261) rolling on a piece of feedback (210a, 260a ) providing, in the locked position, the feedback to the second roller (211, 261), the first and second rollers (211, 261) being coupled with one another in rotation, so as to facilitate passage from the unlocking position to the locking position, characterized in that the roller carrier (300) is movable relative to the housing in rotation about an axis of rotation of the roller carrier (354) parallel to the axis of rotation of the finger (205), the first and second rollers (211, 261) being arranged in a s ymetric with respect to the axis of rotation of the roller carrier (354) and the cam (210a, 260a) and the feedback part (210, 260a) supplying the first and second rollers (211, 261) respectively, approaching the locking position, forces having an axial symmetry about the axis of rotation of the roller carrier (354), and an intermediate roller (231) being mounted around said axis of rotation of the roller carrier (354) so that the second roller (211, 261) bears, in the locked position, on the first roller (211, 261) via the intermediate roller (231) and that the first and second rollers (211,261) are coupled with one another in rotation so that a rotation of the first roller (211, 261) causes a rotation of the second roller (211,261) in the same direction. 2. Locking system according to claim 1, characterized in that the first and second rollers (211, 261) are arranged between two parallel flat flanges constituting a body of the roller holder (300). 3. Locking system according to claim 1 or claim 2, characterized in that the actuating means (300, 350, 211, 231, 261) comprises a lever (350) and a spring (351) for changing the roller carriers (300) from the unlocking position to the locking position by absorbing any resistance to the engagement of the locking fingers in the slots of the wheel (100). 4. Locking system according to one of claims 1 to 3, characterized in that said finger (200, 250) being a first finger, the feedback piece (210a, 260a) is a second locking finger (200 , 250) of the transmission system articulated in rotation on the casing of the locking system around an axis of rotation (205) of the second finger parallel or coincident with the axis of rotation of the first finger (200, 250). 5. Locking system according to claim 4, characterized in that the first and second fingers (200, 250) are symmetrical to each other with respect to a plane of symmetry of the shaft, the axis of rotation (354) of the roller carrier (300) being included in said plane of symmetry. 6. Locking system according to claim 4 or claim 5, characterized in that the first finger (200, 250) is articulated in rotation with respect to the casing around the axis of rotation of the second finger (205) which constitutes a common axis of rotation (205) for the two fingers. 7. Blocking system according to claim 6, characterized in that it comprises a hairpin spring (207) mounted on the common axis of rotation (205) for, when the blocking system is controlled to release the transmission, move aside the locking fingers (200, 250) from each other so as to separate them from the wheel (100). 8. Locking system according to one of claims 4 to 7, characterized in that the first and the second locking finger (200, 250) have shapes which are respectively complementary to diametrically opposite slots of the wheel (100) . 9. Traction power transmission system comprising a power transmission shaft, a notched wheel fixedly mounted on said shaft and a notched wheel locking system according to one of claims 1 to 8 for, by acting on the castle wheel, lock or unlock the system 5 power transmission. 10. Motor vehicle comprising a traction power transmission system according to claim 9 and comprising a parking lock control controlling the evolution of said transmission system from the locking position to the unlocking position by acting on the means 10 actuation (300, 350, 211,231,261). 1/4 ο 250 250 250