Locking mechanism

Abstract

The invention relates to a locking mechanism (1) of a vehicle and comprises: a housing (2); a pawl (3) comprising a locking finger (4) adapted to be engaged in a locking recess, an actuator (7) which moves a movable carriage (8) with a first and second roller (9, 10), a guide rail (11) fixed to the housing, the guide rail forming a fixing wall (12) and a guide wall (13), the first roller being placed in contact with the second roller and the pawl, the second roller being placed in contact with the guide wall, the guide rail being fixed to the housing by a fixing means (16), the guide rail and the fixing means cooperating in such a way that the fixing wall is retained on the housing while being able to be moved relative to this same fixing means. Figure for abstract: Fig. 1

Description

Title of the invention: Locking mechanism

[0001] The present invention relates to a locking mechanism for locking the rotation of a shaft of a transmission chain of a mobility device, such as a motor vehicle for example.

[0002] Locking mechanisms are used, for example, as a parking brake to secure a stationary motor vehicle. In such a case, they make it possible to lock a drive shaft of the motor vehicle in rotation. Such locking mechanisms are used in particular in motor vehicles with automatic transmission, in hybrid vehicles or in electric vehicles. The locking mechanism is intended in particular to immobilize a vehicle, for example a car, in a parked state.

[0003] When the locking mechanism is actuated, its components are likely to be subjected to significant forces. Thus, the components of the locking mechanism must be able to absorb significant forces in order to ensure the reliability of the locking.

[0004] Locking mechanisms are known comprising a movable pawl equipped with a locking finger and pivotally mounted on a transmission casing between a released position and a locking position in which the locking finger is inserted into a locking recess rotationally fixed to the transmission shaft to be locked. The locking mechanism further comprises a linear actuator which moves a movable carriage which is guided in translation on the transmission casing by means of a guide rail. The movable carriage comprises a first roller which cooperates with a cam surface of the movable pawl so that a translational movement of the movable carriage causes the movable pawl to pivot. The movable carriage also comprises a second roller arranged between the first roller and the guide rail. The guide rail is a stamped sheet metal part.It comprises, on the one hand, a fixing wall which is fixed by means of fixing members, such as screws, against a corresponding wall of the transmission casing and on the other hand, a guide wall against which the second roller of the movable carriage rolls and which extends in a plane which is substantially perpendicular to another plane in which the fixing wall extends. The guide wall is placed in support, attached to another corresponding wall of the transmission casing. Each roller has an axis of rotation which is arranged substantially perpendicular to the fixing wall.

[0005] However, due to the manufacturing tolerances required for the part bending procedure, geometric defects in the part may exist. The angle formed between the fixing wall and the guide wall is therefore likely to vary around 90°. In Furthermore, such a guide rail tends to deform under various mechanical stresses. In particular, a lack of parallelism may occur between the guide wall and the wall of the transmission housing against which the guide wall is pressed. This results in a lack of parallelism between the two axes of rotation of the two rollers. All the forces risk being concentrated in one part of the second roller instead of being distributed over its entire height. The rollers may become stuck in relation to the others and not perform their function correctly.

[0006] However, it is important to ensure precise positioning of the guide wall of the guide rail relative to the pawl in order, on the one hand, to guarantee the reliability of the locking and, on the other hand, to prevent excessive forces from passing through the locking mechanism and thus being likely to damage it.

[0007] Thus, it is necessary to provide a locking mechanism which is reliable, economical, easy to implement and supports high loads.

[0008] An idea underlying the invention is a locking mechanism intended to lock a shaft of a vehicle in rotation.

[0009] An idea underlying the invention is a blocking mechanism which makes it possible to solve one or more technical problems of the prior art, for example the aforementioned problems.

[0010] The invention relates to a locking mechanism intended to lock in rotation a transmission shaft of a mobility device equipped with at least one locking recess, the locking mechanism comprising: - a movable pawl comprising a locking finger, the movable pawl being pivotally mounted in a plane about a pivot axis X on a transmission casing between a locking position in which the locking finger is engaged in the locking recess and a released position in which the locking finger is disengaged from said locking recess, the movable pawl comprising a cam surface, - a linear actuator which moves a movable carriage, the movable carriage comprising a first roller and a second roller, - a guide rail fixed to the transmission housing, the mobile carriage being guided by the guide rail, - the guide rail forming a fixing wall and a guide wall attached against a corresponding wall of the transmission housing, the fixing wall and the guide wall being positioned orthogonally to each other, - the first roller is placed with a first axis of rotation arranged perpendicularly to the fixing wall while being placed in contact with the second roller and the movable pawl, - the second roller is placed with a second axis of rotation arranged perpendicularly to the fixing wall while being placed in contact with the guide wall, - the guide rail being mounted fixed to the transmission casing by a fixing means, the guide rail and the fixing means cooperating with each other in such a way that the fixing wall is retained on the transmission casing while being able to be moved relative to this same fixing means.

[0011] Thanks to these characteristics, the guide rail is held to the transmission casing while leaving a clearance which makes it possible to compensate for the geometry defect of the part. By this fixing according to the invention, it is the operating force by the movable ratchet which causes the second roller to be pressed rather than the screw as in the prior art.

[0012] Due to the clearance existing between the fixing wall and the fixing means on the one hand and between the fixing wall and the transmission casing on the other hand, the position of the guide wall of the guide rail can be permanently adjusted to the corresponding wall of the casing while remaining constantly attached to the same wall of the transmission casing. This guarantees that the first roller and the second roller will cooperate as much as possible with their respective axis of rotation Y1, Y2 parallel to each other. This ensures that the forces exerted by the movable pawl will be distributed as uniformly as possible along the rollers and the guide wall.

[0013] According to one embodiment of the invention, the fixing wall is fixed to the transmission housing with a predefined clearance between the fixing means and the transmission housing. The clearance is predefined such that the fixing wall can be moved in space in order to allow adjustment of the guide wall by translation parallel to the corresponding wall of the transmission housing.

[0014] According to one embodiment of the invention, the guide rail is fixed to the transmission casing in such a way that the guide wall can be moved against the corresponding wall of the casing without becoming detached from this same wall, unlike the fixing wall which can be detached from the corresponding wall of the casing.

[0015] According to one embodiment, the fixing wall of the guide rail has a thickness of between 1.5 mm and 3.5 mm; preferably between 2.5 and 3 mm.

[0016] Thanks to these characteristics, when the movable carriage is in relative motion with respect to the guide rail, the friction forces between the movable carriage and the guide rail are reduced. Thus, the movement of the movable carriage is ensured without wear of the movable carriage or the guide rail.

[0017] According to one embodiment of the invention, the fixing means is formed by a shouldered screw having a screw head, a shouldered portion and a rod, the rod being intended to be driven into the transmission casing, the shouldered portion being intended to be positioned above the transmission casing, a length of the shouldered portion between the screw head and the transmission housing being greater than a thickness of the fixing wall of the guide rail. The length of the shouldered portion is measured along an elongation axis of the shouldered screw. The thickness of the fixing wall is measured along an axis parallel to the elongation axis of the shouldered screw.

[0018] According to one embodiment of the invention, the shouldered screw is inserted through an orifice formed in a thickness of the fixing wall, the orifice having a first diameter greater than a second diameter of the shouldered portion of the screw and less than a third diameter of the screw head. Thus, the guide wall cannot be completely detached from the casing because it is retained by the screw head which prevents it from being removed from the transmission casing.

[0019] According to another embodiment; the orifice may also be oblong in shape. Such a shape allows less freedom of movement in a direction parallel to the direction of movement of the carriage, and greater in a perpendicular direction.

[0020] According to one embodiment of the invention, the guide rail is formed in one piece from a folded strip of metal material.

[0021] The invention also relates to a transmission system comprising a shaft equipped with at least one locking recess and a locking mechanism as defined previously.

[0022] According to one embodiment, the shaft comprises a wheel having the at least one locking recess. For example, the wheel is a ratchet wheel.

[0023] According to one embodiment, the wheel comprises 1 to 12 locking recesses.

[0024] According to one embodiment, the plurality of recesses are regularly spaced apart. from each other.

[0025] The invention further relates to a motor vehicle comprising a transmission system as defined above.

[0026] The invention further relates to a gearbox comprising a transmission casing enclosing the locking mechanism as previously described.

[0027] The invention further relates to a transmission system comprising a shaft equipped with at least one locking recess and a locking mechanism as previously described.

[0028] The invention further relates to a motor vehicle comprising a gearbox as previously described.

[0029] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only for illustrative purposes but in no way limit the invention.

[0030] [Fig.l] [Fig.l] is a perspective view of a locking mechanism according to one embodiment;

[0031] [Fig.2A] and [Fig.2B] Figures 2A and 2B illustrate a schematic sectional view of a portion of a locking mechanism according to one embodiment;

[0032] [Fig.3] [Fig.3] illustrates a guide rail in perspective according to the embodiment of [Fig.l].

[0033] [Fig.l] illustrates a locking mechanism 1 for locking a transmission shaft of a vehicle in rotation according to one embodiment of the invention. The locking mechanism 1 is mounted on a transmission housing 2 and comprises a movable pawl 3 comprising a locking finger 4. The movable pawl 3 is pivotally mounted in a plane about a pivot axis X on the transmission housing 2 between a locking position in which the locking finger 4 is engaged in a locking recess 5 and a released position in which the locking finger 4 is disengaged from said locking recess 5. The movable pawl 3 comprises a cam surface 6. The locking mechanism 1 also comprises a linear actuator 7 which moves a movable carriage 8. The movable carriage 8 comprises a first roller 9 and a second roller 10. A guide rail 11 is connected to the transmission housing 2.The movable carriage 8 is guided by the guide rail 11.

[0034] Figures 2A and 2B, the guide rail 11 forms a fixing wall 12 and a guide wall 13. The fixing wall 12 and the guide wall 13 are attached to a corresponding wall 14, 15 of the transmission casing 2. The fixing wall 12 and the guide wall 13 each extend in a plane, perpendicular to each other. The first roller 9 is placed with a first axis of rotation Y1 arranged substantially perpendicular to the fixing wall 12 while being placed in contact with the second roller 10 and the movable pawl 3. The second roller 10 is placed with a first axis of rotation Y2 arranged substantially perpendicular to the fixing wall 12 while being placed in contact with the guide wall 13.

[0035] Figures 2A and 2B, the guide rail 11 is mounted fixed to the transmission casing 2 by means of a shouldered screw 16. The shouldered screw 16 has a screw head 17, a shouldered portion 18 and a rod 19. The rod 19 is driven into the transmission casing 2. The shouldered portion 18 is positioned above the transmission casing 2. The shouldered portion 18 has a length L1, measured along an elongation axis Z of the shouldered screw 16, between the screw head 17 and the transmission casing 2. This length L1 is greater than a thickness E of the fixing wall 12 of the guide rail 11. The thickness E of the fixing wall 12 is measured along an axis parallel to the elongation axis Z of the shouldered screw 16. The elongation axis Z, the rotation axes Y1 and Y2 are approximately parallel to each other.

[0036] The shouldered screw 16 is inserted through an orifice 20 formed in the thickness E of the fixing wall 12. The orifice 20 has a diameter DI greater than a diameter D2 of the shouldered portion 18 of the shouldered screw 16 and less than a diameter D3 of the screw head 17. Thus, the fixing wall 12 is held to the transmission casing 2 by the screw head 17. In another example, the orifice could be oblong in shape (not shown).

[0037] [Fig. 3], the guide rail 1 has a side wall 21 as well as a first longitudinal wall 22 opposite and distant from a second longitudinal wall 23. The second longitudinal wall 23 corresponds to the guide wall 13 as previously described.

[0038] The second longitudinal wall 23, 13 of the guide rail 11 is configured in such a way as to be in contact with the corresponding wall 15 formed by the transmission casing 2, figures 1, 2A and 2B.

[0039] Furthermore, the side wall 21 comprises a notch 25 intended to allow the passage of the linear actuator 7 which is illustrated in [Fig.l]. The notch 25 has a “U” shape.

[0040] The first longitudinal wall 22 of the guide rail 11 has an opening 26 allowing contact between the movable carriage 8 located in the guide rail 11, and the movable pawl 3 located at the opening 26.

[0041] The side wall 21 of the guide rail 11 is a non-return stop for the movable carriage 8 so that the movable carriage 8 is retained in translation in the transmission casing 2, by the guide rail 11.

[0042] The guide rail 11 serves to guide the movable carriage 8 and provides that it only performs the translational movement necessary to actuate the locking finger 4 in the locking recess 5 so that the locking mechanism 1 is in a locking position. The locking position allows, for example, the parking of a motor vehicle.

[0043] The guide rail 11 is manufactured for example from a strip of metal material which is on the one hand cut in order to form the notch 25 then folded three times in the lengthwise direction in order to form said walls which compose it. The metal strip has a rectangular shape before being folded. The metal strip before folding may also comprise a notch intended to form the notch 25 of the guide rail.

[0044] [Fig.l], the movable pawl 3 is of elongated shape and has a first end 31 and a second end 32 distant from the first end 31.

[0045] The first end 31 allows the movable pawl 3 to be fixed to the transmission casing 2 while allowing the rotational movement of said movable pawl 3.

[0046] The second end 32 is located at the opening 26 of the guide rail 11. The second end 32 comprises the cam surface 6 located on a first lateral face of the movable pawl 3, towards the inside of the transmission casing 2. The second end 32 further comprises the locking finger 4 projecting in the opposite direction to the guide rail 11 from a second lateral face of the movable pawl 3. The locking finger 4 is intended, when the locking mechanism is engaged, to be inserted into the locking recess 5. The locking recess 5 is for example located on a ratchet wheel 33 which is capable of receiving said locking finger 4, as illustrated in [Fig.l] and which is fixed in rotation with a transmission shaft 34 to be blocked in rotation.

[0047] The movable pawl 3 further comprises a torsion spring 35. The torsion spring 35 is wound at the first end 31 of the movable pawl 3. The torsion spring 35 comprises a first end portion 36 which bears against a bearing surface of the transmission casing and a second end portion 37 which bears against the second lateral face of the movable pawl 3. The torsion spring 35 is arranged to exert a return force on the movable pawl 3 in order to return it to the released position. The linear actuator 7, partially shown in [Fig.l], which is fixed to the transmission casing 2 comprises a rod 38 capable of being moved in a direction orthogonal to the axes of rotation Y1 and Y2.

[0048] The rod 38 extends through the notch 25 of the guide rail 11 into an internal space of the guide rail 11. The rod 38 is fixed to the movable carriage 8 located in the guide rail 11.

[0049] In cases where the movable carriage 8 is returned backwards by the movable pawl 3 during the dynamic phase, the movable carriage 8 comes into abutment against the side wall 21 of the guide rail 11, which thus forms a non-return stop for the movable carriage 8. The movable carriage 8 is in this case sent against the movable pawl 3 by a return force exerted by a compression spring 39 which surrounds the rod 38 and which has a first end fixed to the body of the actuator 7 and a second end fixed to the movable carriage 8. This effect can occur for example when attempting to engage at too high a speed. Beyond a threshold speed, for example between 3 km / h and 5 km / h, the movable pawl 3 rebounds to prevent engagement, the movable carriage 8 is then returned to the stop.

[0050] The second roller 10 of the movable carriage 8 is capable of being moved along the second longitudinal wall 23, 13 of the guide rail 11. The movable carriage 8 further comprises a cam follower formed by the first roller 9 which is in contact with the cam surface 6 of the movable pawl 3 and capable of being moved along this cam surface 6.

[0051] The mobile carriage 8 further comprises a lug 40 located at the second end 32 of the mobile pawl 3. The lug 40 is intended to retain the mobile pawl 3 in the plane P.

[0052] To move the movable pawl 3 into the locking position, the rod 38 of the linear actuator 7 is moved through the notch 25 of the guide rail 11, thereby moving the movable carriage 8 in a longitudinal direction. The movable carriage 8 is moved from the side wall 21 of the guide rail 11 in the opposite direction. The movement of the movable carriage 8 causes the second roller 10 to move along the second longitudinal wall 23, 13 of the guide rail 11 and the first roller 9 to move along the cam surface 6 of the movable pawl 3. The cam surface 6 has a slope and the movable carriage 8 therefore exerts, via its movement, pressure in the direction of the cam surface 6 of the movable pawl 3. This pressure causes the second end 32 of the movable pawl 3 to rotate in the direction of the locking recess 5 so that the locking finger 4 engages in the locking recess 5 in order to lock the ratchet wheel 33.

[0053] The ratchet wheel 33 has a plurality of recesses 5 regularly spaced from one another, all around the ratchet wheel 33. Each recess 5 of the plurality of recesses has dimensions allowing it to receive the locking finger 4 of the movable pawl 3.

[0054] To move the locking mechanism from the locked position to the released position, the rod 38 is moved so as to move the movable carriage 3 towards the side wall 21 until it abuts against the side wall 21 of the guide rail 11. The locking finger 4 is released from the locking recess 5 present on the ratchet wheel 33 which releases said ratchet wheel 33 and thus allows rotation of the transmission shaft 34.

[0055] The use of the verb “comporter”, “comprendre” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0056] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. Gearbox comprising a transmission housing (2) and a locking mechanism (1) enclosed in the transmission housing, the locking mechanism being intended to lock in rotation a transmission shaft of a mobility device equipped with at least one locking recess (5), the locking mechanism comprising: - a movable pawl (3) comprising a locking finger (4), the movable pawl being pivotally mounted in a plane about a pivot axis X on the transmission housing (2) between a locking position in which the locking finger is engaged in the locking recess and a released position in which the locking finger is disengaged from said locking recess, the movable pawl comprising a cam surface (6), - a linear actuator (7) which moves a movable carriage (8), the movable carriage comprising a first roller (9) and a second roller (10),- a guide rail (11) fixed to the transmission casing, the movable carriage being guided by the guide rail, - the guide rail forming a fixing wall (12) and a guide wall (13) attached to a corresponding wall (14, 15) of the transmission casing, the fixing wall and the guide wall being positioned orthogonally to each other, - the first roller is placed with a first axis of rotation (Yl) arranged perpendicular to the fixing wall while being placed in contact with the second roller and the movable pawl, - the second roller is placed with a second axis of rotation (Y2) arranged perpendicular to the fixing wall while being placed in contact with the guide wall, - the guide rail being mounted fixed to the transmission casing by a fixing means (16),the guide rail and the fixing means cooperating with each other in such a way that the fixing wall is retained on the transmission housing while being able to be moved relative to this same fixing means.,

2. Gearbox according to claim 1, in which the means for fixing the locking mechanism is formed by a shouldered screw (16) having a screw head (17), a shouldered portion (18) and a rod (19), the rod being intended to be driven into the transmission housing, the shouldered portion being intended to be positioned above the transmission housing. transmission, a length (L) of the shouldered portion being greater than a thickness (E) of the fixing wall of the guide rail.

3. A gearbox according to claim 2, wherein the shouldered screw of the locking mechanism is inserted through an orifice (20) formed in the thickness of the fixing wall, the orifice having a first diameter (D1) greater than a second diameter (D2) of the shouldered portion of the screw and less than a third diameter (D3) of the head of

4. screw. A gearbox according to claim 2, wherein the shouldered screw of the locking mechanism is inserted through an orifice formed in the thickness of the fixing wall, the orifice being oblong in shape.

5. Gearbox according to one of claims 1 to 4, wherein the guide rail of the locking mechanism is formed in one piece from a folded strip of metal material.

6. A transmission system comprising a shaft equipped with at least one locking recess and a gearbox locking mechanism according to any one of claims 1 to 5.

7. Motor vehicle comprising a gearbox according to one of claims 1 to 5.

8. A motor vehicle comprising a transmission system according to claim 6.

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