Parking brake lock incorporating a shape-memory material

Abstract

The invention relates to a parking brake locker (60) for a wheel of a motorized road vehicle. The brake locker (60) includes a latch (62) that is movable between a locked position when the parking brake is engaged and / or a released position. The brake locker (60) includes an actuating material (66a) that is configured to cause the latch (62) to move between the unlocked position and the locked position by deforming the actuating material (66a) during a temperature change in the actuating material (66a). (Fig. 5)

Description

Title of the invention: PARKING BRAKE LOCK COMPRISING A SHAPE MEMORY MATERIAL Technical field of the invention

[0001] The invention relates to the braking of a motorized road vehicle, such as a car or a van. More specifically, the invention concerns locking a parking brake of a vehicle wheel in the engaged and / or released position. Prior art

[0002] Motorized road vehicles such as automobiles have parking brakes, each of which includes a locking mechanism to lock the parking brake in the engaged position. The brake locking mechanism described in [Fig. 3] of US Patent 7,828,124 B2 includes a linear actuator comprising a solenoid and a latch that pivots under the action of the linear actuator.

[0003] There is a risk of failure of the linear actuator incorporating the solenoid. Furthermore, the linear actuator is generally heavy and bulky in order to be sufficiently reliable. However, the space within a parking brake for housing a locking mechanism is often limited, which makes the parking brake more complex to manufacture. Description of the invention

[0004] The invention aims to overcome all or part of the drawbacks of the prior art. In this regard, the invention relates to a parking brake lock for a wheel of a motorized road vehicle. The brake lock comprises a latch that is movable between a position in which the brake is not locked and a position in which it is locked, the parking brake being in the engaged position when the latch is in the locked position and / or the parking brake being in the released position when the latch is in the locked position.

[0005] According to the invention, the blocker comprises an actuating material which is configured to induce the movement of the latch between the position of no latch blockage and the position of latch blockage, by deformation of the actuating material during a temperature variation of the actuating material.

[0006] Thanks to the blocker as claimed, the safety of the motor vehicle is improved by allowing reliable locking and / or unlocking of the parking brake for a wheel of the vehicle, while limiting the mass and the bulk of the parking brake while still having a parking brake that is relatively simple to manufacture.

[0007] In particular, the safety of the parking brake is improved due to the increased reliability of the blocker comprising the actuation material compared to a blocker comprising a linear solenoid actuator and known from the prior art.

[0008] The blocker incorporating the actuation material is lighter and more compact than a blocker comprising a linear solenoid actuator known in the prior art. Furthermore, the actuation material can be arranged spatially more easily than a linear solenoid actuator in a parking brake.

[0009] The parking brake is in particular simpler to manufacture with a blocker comprising the actuation material than with a blocker comprising a linear solenoid actuator, for example due to the greater freedom of spatial arrangement of the actuation material and the simplicity of the actuation material compared to a linear solenoid actuator.

[0010] According to one embodiment, the actuation material is a shape-memory material. Preferably, the shape-memory material comprises a metallic shape-memory material such as a nickel-titanium alloy. Preferably, the shape-memory material is a double-acting shape-memory material.

[0011] According to another embodiment, the actuating material is configured to be heated to deform from a second position in which the latch is in the unblocked position to a first position in which the latch is in the blocked position. Preferably, the actuating material is configured to be heated to a temperature above a threshold temperature of 120°C at which the actuating material deforms from the second position to the first position.

[0012] According to one embodiment, the actuating material is electrically conductive and has a non-zero electrical resistance. The actuating material is configured to be heated by passing an electric current through it, causing it to deform between the second and first positions. Preferably, the brake lock includes a brake lock monitoring device comprising a voltage measuring tool and / or a current measuring tool for measuring the current through the actuating material.

[0013] According to another embodiment, the blocker comprises a first elastic element which is configured to urge the latch towards the blocking position or towards the position of no blockage. The first elastic element includes the actuating material. Preferably, the first elastic element includes a return spring, such as a spiral spring or a leaf spring.

[0014] According to one embodiment, the locking device includes a second elastic element configured to elastically force the latch towards the unblocked position or towards the blocked position in the opposite direction to that of the first elastic element. Preferably, the second elastic element is configured to force the latch with a second elastic force greater than that of the first elastic force exerted by the first elastic element, assuming no temperature change in the first elastic element. Preferably, the second elastic element includes a return spring, such as a helical spring or a leaf spring.

[0015] According to another embodiment, the locking device includes a latch retainer comprising a tooth and a recess, the retainer being configured to hold the latch in the locked position when the tooth engages the recess by means of a form cooperation. Preferably, the locking device is configured to release the latch from its retention by the retainer by driving a transmission element, in particular by electromechanical drive from a parking brake motor assembly.

[0016] According to one embodiment, the blocker includes a stop configured to stop the latch in the position of no blockage.

[0017] According to another embodiment, the latch is a pivoting lever between the unblocked position and the blocked position. The stop is configured to limit the rotation of the latch and to stop the latch in the unblocked position.

[0018] The invention also relates to a parking brake for braking a wheel of a motorized road vehicle, comprising a brake blocker as defined above.

[0019] According to one embodiment, the brake is an electromechanical brake comprising a drive assembly including a geared motor and a screw-nut drive device. Preferably, the screw-nut drive device is reversible.

[0020] According to another embodiment, the parking brake is a disc brake. Preferably, the disc brake is a disc brake with a floating caliper.

[0021] The invention also relates to a parking braking method using a parking brake as defined above. The parking braking method comprises parking the brake on one wheel of the motorized road vehicle. The parking braking method includes a temperature variation of the actuation material, in particular by heating, to deform the actuation material towards the first position so that the latch is in the locking position, locking the parking brake in the engaged position. Brief description of the figures

[0022] The present invention will be better understood upon reading the description of non-limiting examples of embodiments, with reference to the accompanying figures, which illustrate: • [Fig.1]: a schematic representation partially in longitudinal section of a disc brake which includes a parking brake locker according to a first embodiment of the invention; • [Fig.2]: a partial schematic cross-sectional and front-view representation of the disc brake which includes a parking brake locker according to the first embodiment of the invention; • [Fig.3]: a schematic perspective representation of a drum brake which includes a parking brake blocker according to a second embodiment of the invention; • [Fig.4]: the operation of a blocker according to the first embodiment or the second embodiment in the position of no blockage in the position of the parking brake being released; • [Fig.5]: the operation of a blocker according to the first embodiment or the second embodiment in the blocking position in the engaged position of the parking brake; • [Fig.6]: a method of braking a parking brake according to the first embodiment or according to the second embodiment. Detailed description of at least one embodiment

[0023] For clarity, identical elements are identified by identical reference signs from one figure to another.

[0024] Figures 1 and 3 each represent a parking brake 2 for a wheel of a motor vehicle, for example, a car or a van. The motor vehicle preferably comprises four wheels and a parking brake 2 on each non-steering wheel and / or on each non-drive wheel of the vehicle. The parking brake 2 is configured to brake the wheel when the parking brake 2 is in the engaged position. The parking brake 2 is configured to allow the wheel to rotate when the parking brake 2 is in the disengaged position. The parking brake 2 is also, for example, an emergency brake and / or a service brake for the motor vehicle.

[0025] With joint reference to [Fig. 1] and [Fig. 3], the parking brake 2 is an electromechanical brake comprising a motor assembly 10, 20. The motor assembly 10, 20 includes a geared motor 14, 24 and a device drive 12, 22. In each of the embodiments shown, the motorization assembly 10 is reversible. The drive device 12, 22 is, for example, a screw-nut drive device.

[0026] Figure 1 shows a parking brake 2, which is a disc brake 4. In the embodiment shown, the disc brake 4 is a floating caliper disc brake. The disc brake 4 comprises a floating caliper 40, a yoke 41, brake shoes 42, a disc 43, a piston 11, and a motor assembly 10. When the disc brake 4 is also a hydraulic service brake, it also includes a hydraulic chamber 47. The disc brake 4 is configured to brake the corresponding wheel by friction of the brake shoes 42 on the disc 43, which is rigidly attached to the wheel.

[0027] The drive assembly 10 comprises the screw-nut drive device 12 and a geared motor 14. The drive assembly 10 is configured to drive the piston 11 in translation towards the disc 43 along a longitudinal direction Yl-Yl of the disc brake. The screw-nut drive device 12 includes a screw 13 and a nut 15 which is configured to mechanically engage the screw 13. One of the screw 13 and nut 15 is a driving element which is movable in rotation and fixed in translation relative to the longitudinal direction Yl-Yl of the disc brake, the other of the screw 13 and nut 15 is the driven element which is movable in translation and fixed in rotation relative to the longitudinal direction Yl-Yl of the disc brake. The screw-nut drive device 12 is configured to drive the piston 11 towards the disc 43.The screw-nut drive device 12 is reversible and operates, for example, by friction, ball bearing, or roller bearing. The geared motor 14 comprises an electric motor and a gearbox that is driven by the electric motor. The gearbox includes transmission elements 18, such as a gear wheel, which is visible in [Fig. 2] and [Fig. 4]; it is configured to drive the screw-nut drive device 12. The gearbox is reversible.

[0028] With reference to [Fig.2] and [Fig.3], the parking brake 2 includes a brake blocker 60 which is configured to block the parking brake 2 in the engaged position and / or in the released position.

[0029] With more specific reference to [Fig. 2], the locking device 60 is configured to prevent rotation about the longitudinal axis Yl-Yl of the brake of a toothed wheel which is a transmission element 18 of a geared motor 14 which is closer to the electric motor than to the output of the geared motor. The locking device 60 notably locks the parking brake 2 in the engaged position.

[0030] Figure 3 represents a parking brake 2, which is a drum brake 3. The drum brake 3 comprises a drum (not shown), a plate 30, a first segment 32, a second segment 33, a motor assembly 20, and advantageously a backlash compensation link 37. When the drum brake 3 is also a hydraulic service brake, the drum brake 3 also includes a wheel cylinder 36. The drum brake 3 is configured to brake the corresponding wheel by friction of the segment linings 35 against the drum.

[0031] The plate 30 is centered around a drum brake rotation axis Y2-Y2, which is a longitudinal axle axis of the motor vehicle. The backlash compensator 37 is configured to compensate for wear generated by the friction of the linings 35 against the drum.

[0032] The drive assembly 20 comprises the screw-nut drive device 22 and a geared motor 24. The drive assembly 20 is configured to drive the segments 32, 33 against the drum during parking braking. The screw-nut drive device 22 is configured to drive at least one of the two pushers 21 of the drive assembly 10 in translation towards one of the corresponding segments 32, 33 when driven by the geared motor 24. The screw-nut drive device 22 is reversible. The geared motor 24 comprises an electric motor and a gearbox which is driven by the electric motor. The gearbox includes transmission elements 18 such as a gear which is visible in [Fig. 4], and is configured to drive the screw-nut drive device 22 when driven by the electric motor. The reducer is reversible.

[0033] In each of the embodiments shown and with joint reference to Figures 2 to 5, the parking brake lock 60 is configured to lock the parking brake 2 in the engaged position of the parking brake 2. The brake lock 60 comprises a latch 62, a first elastic element 66, a second elastic element 68, a stop 67, a retaining member 70, an electrical supply member 69 and a monitoring member 50. The brake lock 60 is in particular configured to block the drive of a transmission element 18 of the drive assembly 10, 20 when the latch 62 is in the locked position.

[0034] The latch 62 is movable between a locked position when the parking brake 2 is engaged and a non-locking position when the parking brake 2 is disengaged. The latch 62 forms, for example, a lever that is rotatable about a pivot point 61. The latch 62 is configured to pivot between the non-locking position and the locked position. The non-locking position is also called the unlocked position of the latch 62. The latch 62 is configured to lock the parking brake 2 in the engaged position when the latch 62 is in the locked position. The latch 62 is configured to release the parking brake 2 when it is in the non-locking position, so that the parking brake 2 can move from the engaged position to the disengaged position and vice versa.

[0035] The brake lock 60 is specifically configured to block the drive of a transmission element 18 of the drive assembly 10 when the latch 62 is in the locked position. The transmission element 18 is a transmission element of the geared motor 14, 24 and / or a transmission element 18 of the drive device 12, 22. The transmission element 18 is, for example, a gear that is blocked from rotating when the latch 62 is in the locked position.

[0036] The first elastic element 66 comprises a return spring, preferably a helical spring, a leaf spring, or a torsion spring. The first elastic element 66 comprises an actuating material 66a that is deformable between a first position P1 and a second position P2 by a temperature change in the actuating material 66a. The first elastic element 66 is configured to force the latch 62 towards the locked position or towards the unlocked position. In each of the embodiments shown, the first elastic element 66 is configured to elastically force the latch 62 towards the locked position, particularly in the absence of a temperature change in the actuating material 66a.The first elastic element 66 is configured to force the latch 62 towards the locking position by deforming the actuating material 66a between the second position P2 and the first position PI during a sufficient temperature variation of the actuating material 66a.

[0037] The actuating material 66a is configured to deform mechanically between a second position P2 and a first position PI when the temperature of the actuating material 66a varies with respect to a threshold temperature value TL. In particular, the actuating material 66a is configured to deform mechanically from the second position P2, in which the latch 62 is in the unblocked position, to the first position PI, in which the latch 62 is in the blocked position, and vice versa, with respect to the temperature variation. The actuating material 66a is, for example, a shape-memory material that is configured to deform from the second position P2 to the first position PI when the temperature of the actuating material 66a increases above the threshold temperature value Tl, which is, for example, equal to 120°C.The actuation material 66a is preferably a double-acting shape-memory material in which the first position PI is a stable position of the actuation material 66a and in which the second position P2 is a stable position of the actuation material 66a. The actuation material 66a is in particular a metallic shape-memory material. The metallic shape-memory material is, for example, an alloy comprising nickel and titanium.

[0038] In each of the embodiments shown, the actuation material 66a is configured to elongate upon a temperature increase above from a temperature threshold value Tl towards the first position PI of the actuating material 66a. The actuating material 66a is configured to retract, upon a temperature decrease below the temperature threshold value Tl, towards the second position P2 of the actuating material 66a. The actuating material 66a is specifically configured to force the latch 62 towards the locking position by exerting a deformation force that has an intensity greater than the intensity of a second elastic force of the second elastic element 68 when the actuating material 66a is deformed from the second position P2 to the first position PI by a temperature change.

[0039] The actuation material 66a is electrically conductive and exhibits a non-zero first electrical resistance, unlike a superconductor, for example. The actuation material 66a is configured to be heated by passing an electric current through it, causing it to deform between the second position P2 and the first position PL.

[0040] The parking brake 2 includes a power supply element 69 for the actuating material 66a. The power supply element 69 is configured to heat the actuating material 66a above the threshold temperature value Tl by passing an electric current through the actuating material 66a. The power supply element 69 is configured to supply the actuating material 66a electrically, preferably from a geared motor 14, 24 of the parking brake 2 and / or from the vehicle battery.

[0041] The second elastic element 68 comprises a return spring, preferably a helical spring or a leaf spring. The second elastic element 68 is configured to elastically load the latch 62 towards the unblocked position or towards the blocked position in a direction opposite to that of the first elastic element 66. In the embodiment shown, the second elastic element 68 is configured to elastically load the latch 62 towards the unblocked position. In particular, the second elastic element 68 is configured to load the latch 62 with a second elastic force that has a greater intensity than the first elastic force exerted by the first elastic element 66 in the absence of temperature variation of the actuating material 66a.

[0042] The monitoring element 50 of the blocker includes a voltage measuring tool and / or a current measuring tool for the actuating material 66a. The monitoring element 50 is configured to detect electrical power passing through the blocker 60, which may or may not deform the actuating material 66a by heating. The monitoring element 50 is configured to monitor the operation of the brake blocker 60, by detecting in particular any risk of untimely blocking of the blocker 60.

[0043] The stop 67 is configured to stop the latch 62 in the unblocked position, particularly when the actuating material 66a is in the second position P2. In each embodiment shown, the latch 62 is a lever, and the stop 67 is a rotation stop configured to limit the rotation of the latch 62 by stopping its rotation in the unblocked position.

[0044] More generally, the second elastic element 68 and the stop 67 together form a retaining member which is configured to maintain the latch 62 in the position of no blockage in the absence of temperature variation of the actuating material 66a.

[0045] The retaining member 70 of the latch is configured to retain the latch 62 in the locked position, particularly when the actuating material 66a is in the first position PL. The retaining member 70 comprises a tooth 63 and a recess 71. The tooth 63 is configured to engage the recess 71 by form cooperation to lock a transmission element 18 of the parking brake 2. In each of the embodiments shown, the transmission element 18, which is intended to be locked, comprises the recess 71 and the latch 62 includes the tooth 63. The recess 71 is a notch, in particular between two teeth of a gear.

[0046] The blocker 60 is configured to release the latch 62 from a retention in the locked position by the retaining member 70 by driving the transmission element 18. In each of the embodiments shown, the latch 62 is released from the retaining member 70 by electromechanical drive of the transmission assembly 18 by actuation of the motorization assembly 10, 20.

[0047] With reference to [Fig. 4], the latch 62 of the brake lock 60 is in the unblocked position. The actuating material 66a is in the second position. The latch 62 is forced towards the unblocked position by the second elastic element 68 along the longitudinal direction X2-X2 of the second elastic element. The stiffness of the second elastic element 68 is greater than that of the first elastic element 66, which tends to elastically force the latch 62 in the opposite direction. The first elastic element 66 and the second elastic element 68 are, for example, each helical springs made of metallic material.

[0048] The latch 62 is stopped in the non-blocking position by the stop 67. The retaining member 70 has released the latch 62. The tooth 63 of the latch 62 is mechanically disengaged from the recess 71 of the transmission element 18. The monitoring member 50 does not detect any power passing through the actuating material 66a, in particular no current passing through the actuating material 66a and no voltage across the terminals of the actuating material 66a.

[0049] With reference to [Fig. 5], the latch 62 of the brake blocker 60 is in the locked position. The actuating material 66a is in the first position PI. The latch 62 is forced towards the locked position by the actuating material 66a along the longitudinal direction Xl-Xl of the first elastic element. The force exerted by the actuating material 66a and the elastic force of the first elastic element 66 are greater than the force exerted by the elastic element 68 on the latch 62 when the temperature of the actuating material 66a is above the threshold temperature value TL. The first elastic element 66 and the second elastic element 68 are, for example, each helical springs made of metallic material.

[0050] The latch 62 is held in the locked position by the retaining member 70. The tooth 63 of the latch 62 mechanically engages the recess 71 of the transmission element 18. The stop 67 has ceased to hold the latch 62 in the unlocked position. The monitoring member 50 detects power flowing through the actuating material 66a when the actuating material 66a is heated, in particular a current flowing through the actuating material 66a and / or a voltage across the terminals of the actuating material 66a.

[0051] Figure 6 illustrates the parking braking method 100, which is implemented by a parking brake 2 according to the invention, such as the disc brake 4 shown in Figure 1 or the drum brake 3 shown in Figure 3. The parking braking method 100 comprises a parking brake 101 of the vehicle, implementing the geared motor 14, 24, in particular of at least one wheel of the vehicle. The parking brake 101 preferably comprises the application of each of the vehicle's parking brakes 2.

[0052] The parking braking method 100 includes a temperature variation 103 of the actuating material 66a of at least one blocker 60 and preferably of each brake blocker 60, in particular heating the actuating material 66a above the threshold temperature value Tl, to deform the actuating material 66a from the second position P2 to the first position PI and for the latch 62 to move from the position of no blockage to the blockage position.

[0053] The braking method 100 includes locking 105 the parking brake 2 in the engaged position. The actuating material 66a is in the first position P1 and the latch 62 is in the locked position. The retaining member 70 holds the latch in the locked position, even when the actuating material 66a cools and tends to deform, returning to the second position P2.

[0054] The parking braking procedure 100 includes the release 107 of the parking brake 2 and the loosening of the parking brake 2. The release of the brake Parking 2 includes the release of the latch 62 by the retaining member 70 from the locked position. The transmission element 18 is driven, in particular in rotation, by electromechanical drive, in particular directly or indirectly by the geared motor 14, 24 of the drive assembly 10, 20, to release the latch 62. The latch 62 moves from the locked position to the unlocked position, in particular by pivoting.

[0055] Thanks to the blocker 60, the safety of the motor vehicle is improved by allowing a reliable locking of the parking brake 2 and / or unlocking of a parking brake 2 for a wheel of the vehicle, while limiting the mass and size of the parking brake 2 and while having a parking brake 2 that is relatively simple to manufacture.

[0056] In particular, the safety of the parking brake 2 is notably improved due to the increased reliability of the blocker 60 comprising the actuation material 66 compared to a blocker comprising a linear solenoid actuator and known from the prior art.

[0057] The blocker 60 comprising the actuation material 66 is lighter and more compact than a blocker 1 comprising a linear solenoid actuator and known in the prior art. Furthermore, the actuation material 66 can be arranged spatially more easily than a linear solenoid actuator in a parking brake 2.

[0058] The parking brake 2 is in particular simpler to manufacture with a blocker 60 comprising the actuation material 66 than with a blocker comprising a linear solenoid actuator, for example due to the greater freedom of spatial arrangement of the actuation material 66 and the simplicity of the actuation material 66 compared to a linear solenoid actuator.

[0059] When the transmission element 18 is a transmission element of the geared motor reducer 14, 24 which is closer to an input of the reducer than to an output of the reducer, the torque which is likely to be exerted on the latch 62 is limited.

[0060] Of course, various modifications can be made by a person skilled in the art to the invention which has just been described without going out of the scope of the disclosure of the invention.

[0061] Alternatively, vehicle 1 comprises three wheels such as a bicycle or more than four wheels such as a truck.

[0062] Alternatively, the disc brake 4 is a disc brake with a fixed caliper or with multiple discs. Alternatively, the parking brake 2 is a drum brake and a disc brake, for example a "drum-in-hat" type brake.

[0063] Alternatively, the service brakes are separate from the parking brakes 2.

[0064] In addition or alternatively, the screw-nut drive device 12 of the parking brake is irreversible. In addition or alternatively, the drive assembly 10, 20 includes a ball in a "bail in ramp" type drive device which includes the blocker 60, also known as a ball on ramp system.

[0065] Alternatively, the brake lock 60 is configured to lock the parking brake 2 in the released position when the latch 62 is in the locked position. In addition, or alternatively, the brake lock 60 is configured to lock the parking brake 2 in the engaged position and to lock the parking brake in the released position.

[0066] Alternatively, when the parking brake 2 is a drum brake 3, the self-adjusting link 37 includes the brake lock 60. The brake lock 60 is then configured, for example, to lock a transmission element 18 of the self-adjusting link 37, such as a gear.

[0067] Alternatively, when the parking brake 2 is a drum brake 3, the parking brake 2 is devoid of a play-compensating billet 37.

[0068] Alternatively, the latch 62 is movable in translation along the longitudinal direction XI-XI of the first elastic element 66 when the latch 62 moves between the position of no blocking and the blocking position.

[0069] In addition or alternatively, the first elastic element 66 includes elastic washers such as Belleville washers.

[0070] Alternatively, a wire comprises the actuation material 66a, the length of the wire being modified during a temperature variation of the actuation material 66a to deform the actuation material 66a between the second position and the first position.

[0071] Alternatively, the actuation material 66a is a non-metallic shape memory material such as a polymer or a ceramic, provided that the shape memory material remains compatible with use in a parking brake 2.

[0072] In addition or alternatively, the shape memory material is a single-effect shape memory material which has a single stable position of the shape memory material which is the first position PI of the actuation material 66a.

[0073] In addition or alternatively, the actuation material 66a is configured to retract when the temperature rises above the threshold temperature value Tl, preferably towards the first position PI of the actuation material 66a.

[0074] In addition or alternatively, the actuation material 66a is configured to elongate when the temperature decreases below the threshold temperature value Tl, preferably towards the second position P2 of the actuation material 66a.

[0075] In addition or alternatively, the actuation material 66a is electrically insulating.

[0076] In addition or alternatively, the parking brake 2 includes a component of heating near the actuation material 66a to heat the material

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] actuation 66a, in addition to or instead of the electrical supply member 69 of the actuation material 66a. In addition or as an alternative, the second elastic element 68 includes elastic washers such as Belleville washers. In addition, or alternatively, the second elastic element 68 includes an actuating material that is deformable by temperature variation, for example, a shape-memory material. The actuating material of the second elastic element 68 serves, for example, to release the latch 62 when the latch 62 is held in the unblocked position by the retaining member 70. The monitoring device 50 is configured for example to indirectly monitor the actuating material 66a when the power supply device 69 is a heating device which is located near the actuating material 66a. In addition or alternatively, the latch 62 is configured to move axially and the stop 67 is an axial stop for the latch 62. In addition or as an alternative, the blocker 60 includes a stop to stop the latch 62 in the position of no blockage, for example an axial stop and / or a rotation stop. In addition or alternatively, the latch 62 includes the recess 71 and the transmission element 18 includes the tooth 63, the retaining member 70 being configured to retain the latch 62 by cooperation of form between the tooth 63 and the recess 71. LIST OF DIGITAL REFERENCES 2 Parking brake 3 Drum brake 4 Disc brake 10 Motor assembly 11 Piston 12 Screw-nut drive unit 13 Screw 14 Gearmotor 15 Nut 18 Transmission element 20 Drum brake motor assembly 21 Pushrod 22 Screw-nut transmission device 24 Gearmotor 30 Plate 32 First segment 33 Second segment 35 Brake lining 36 Wheel cylinder 37 Backlash compensating link 40 Floating caliper 41 Clevis 42 Shoe 43 Disc 47 Hydraulic chamber 50 Locking device monitoring element 60 Locking device 61 Pivot point 62 Latch 63 Tooth 66 First elastic element 66a Actuation material 67 Stop 68 Second elastic element 69 Power supply element 70 Retaining element 71 Recess PI First stable position P2 Second stable position Tl First temperature threshold value Yl-Yl Longitudinal direction of the disc brake Y2-Y2 Direction of drum rotation XL-XL Longitudinal direction of the first elastic element X2-X2 Longitudinal direction of the second elastic element 100 Parking brake procedure 101 Parking brake 103 Temperature variation and deformation of the actuating material by moving the latch towards the locking position 105 Latch locking 107 Parking brake release by releasing the latch which moves towards the unlocked position

Claims

Demands

1. Parking brake (2) locker (60) for a motor vehicle wheel, comprising a latch (62) that is movable between a non-locking position and a locking position, the parking brake (2) being in the engaged position when the latch (62) is in the locking position and / or the parking brake (2) being in the released position when the latch (62) is in the locking position, characterized in that the brake locker (60) comprises an actuating material (66a) that is configured to induce the movement of the latch (62) between the non-locking position and the locking position by deformation of the actuating material (66a) during a temperature variation of the actuating material (66a).

2. Brake blocker (60) according to the preceding claim, wherein the actuation material (66a) is a shape memory material, the shape memory material preferably comprising a metallic shape memory material such as an alloy comprising nickel and titanium, and / or the shape memory material preferably being a double-acting shape memory material.

3. Brake blocker (60) according to any one of the preceding claims, wherein the actuating material (66a) is configured to be heated, preferably to a temperature above 120°C, to deform from a second position (P2) in which the latch (62) is in the no-blocking position to a first position (PI) in which the latch (62) is in the blocking position.

4. Brake locker (60) according to the preceding claim, wherein the actuating material (66a) is electrically conductive and the actuating material (66a) has a first non-zero electrical resistance, the actuating material (66a) being configured to be heated by passing an electric current through the actuating material (66a) to deform between the second position (P2) and the first position (PI), the brake locker (60) preferably comprising a brake locker monitoring element (50) comprising a voltage measuring tool and / or a current measuring tool through the actuating material (66a).

5. Brake locker (60) according to any one of the preceding claims, wherein the brake locker (60) comprises a first elastic element (66) which is configured to strain the latch (62) towards the locking position or towards the non-locking position, the first elastic element (66) comprising the actuating material (66a), the first elastic element (66) preferably comprising a return spring, such as a helical spring and / or a leaf spring.

6. Brake locker (60) according to the preceding claim, wherein the brake locker (60) comprises a second elastic element (68) which is configured to elastically stress the latch (62) towards the no-lock position or towards the lock position in a direction opposite to that of the first elastic element (66), the second elastic element (68) in particular being configured to stress the latch (62) with a second elastic force which has an intensity greater than that of a first elastic force which is exerted by the first elastic element (66) in the absence of temperature variation of the first elastic element (66), the second elastic element (68) preferably comprising a return spring, such as a helical spring and / or a leaf spring.

7. Brake locker (60) according to any one of the preceding claims, wherein the brake locker (60) comprises a latch retainer (70) comprising a tooth (63) and a recess (71), the retainer (70) being configured to retain the latch (62) in the locking position when the tooth (63) engages the recess (71) by form cooperation, the brake locker (60) preferably being configured to release the latch (62) from a retainer by the retainer (70) by driving a transmission element (18), in particular by electromechanical drive by a parking brake drive assembly (10).

8. Brake locker (60) according to any one of the preceding claims, wherein the latch (62) is a pivoting lever between the non-locking position and the locking position, the brake locker (60) comprising a stop (67) configured to limit a rotation of the latch (62) and to stop the latch (62) in the non-locking position.

9. Parking brake (2) for a motor vehicle wheel, comprising a brake blocker (60) according to any one of the previous claims, wherein the parking brake (2) is an electromechanical brake which includes a motorization assembly (10, 20) which comprises a geared motor (14) and a screw-nut drive device (12, 22), and / or wherein the parking brake (2) is a disc brake (4), the screw-nut drive device (12, 22) preferably being reversible, and / or the disc brake (4) preferably being a floating caliper disc brake.

10. A parking braking method (100) using a parking brake (2) according to the preceding claim, the parking braking method (100) comprising a parking brake (101) of a wheel of the motorized road vehicle, a temperature variation (103) of the actuating material (66a), in particular by heating, to deform the actuating material (66a) towards the first position (PI) so that the latch (62) is in the locking position by locking the parking brake (2) in the engaged position.

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