WO2023202826A1 - Clamping device for a braking system comprising a reduction mechanism comprising an epicyclic gear train - Google Patents

Abstract

The invention relates to a clamping device (7) for a brake system, which device is intended to exert a relative movement between friction elements and includes a frame (10) supporting an electric actuator, which is intended to provide the clamping force, and a reduction mechanism (17), which couples an output shaft of the electric actuator to a mechanism (13) for converting the rotational movement of the output shaft into translational movement to allow relative movement between the friction elements. The reduction mechanism comprises an epicyclic gear train including: • - a planetary gear for receiving the rotational movement of the output shaft, and • - an assembly (19) forming a ring gear for delivering the output rotational movement to the conversion mechanism. The clamping device comprises means (25) for transforming the assembly forming a ring gear between a configuration for delivering the output rotational movement and a configuration for blocking the output rotational movement.

Description

Clamping device for a braking system comprising a reduction mechanism comprising an epicyclic gear train

The invention relates to the field of braking systems for vehicles, more particularly braking systems of the electromechanical type.

A braking system of a vehicle, in particular an automobile, generally comprises mechanical clamping devices comprising in particular friction elements, such as brake pads, connected to an actuator capable of bringing a pair of these friction elements together in the direction of two opposite faces of a disc secured to a wheel of the vehicle to grip it and thus brake the vehicle by friction of the friction elements against the disc, or to move them apart in order to stop braking.

In the case of electromechanical type braking systems, the mechanical clamping devices comprise at least one electric actuator such as a motor equipped with a rotating output shaft. Consequently, these mechanical clamping devices of the electromechanical type must include a mechanism for converting the rotational movement of the output shaft of the electric actuator into the translational movement necessary for bringing the friction elements together.

Conventionally, electromechanical type tightening devices are designed so that the tightening is of the irreversible type, that is to say that the tightening system is self-locking. Thus, once the clamping force is applied, it is maintained by mechanical blocking until rotation in the opposite direction of the rotating shaft of the electric motor is commanded. This assembly has the advantage, in the case of a parking brake, of ensuring that the clamping force is maintained even when the vehicle is stationary and the electricity supply to the motor is interrupted.

However, despite these advantages for parking braking, such clamping devices have disadvantages, notably faster wear of the parts used, and it is generally preferable for use as a service brake that the clamping device is of reversible type, that is to say that the tightening system is of the non-self-locking type.

The invention aims in particular to propose a tightening device for a braking system making it possible, depending on the situation, to obtain self-locking type tightening or non-self-locking type tightening.

To this end, the subject of the invention is a clamping device for a braking system intended to exert a relative movement between friction elements and comprising a frame supporting an electric actuator intended to provide the clamping force and a mechanism for reducing the force. rotation speed coupling an output shaft of the electric actuator to a mechanism for converting the rotational movement of the output shaft into translational movement in order to allow the relative displacement movement between the friction elements,
in which the rotation speed reduction mechanism comprises an epicyclic gear train comprising:
- a planetary pinion for receiving the rotational movement of the output shaft of the electric actuator, and
- a crown assembly for delivering the output rotational movement to the conversion mechanism,
characterized in that the clamping device comprises means for transforming the crown assembly between a configuration for delivering the output rotational movement and a configuration for blocking the output rotational movement.

The tightening device according to the invention thus makes it possible to combine the advantages of a reversible or non-self-locking type tightening device and an irreversible or self-locking type tightening device by switching from one to the other on order using the transformation means. In fact, the clamping device can have two configurations under the action of the transformation means. The delivery configuration corresponds to a reversible or non-self-locking type configuration of the clamping device in which the movement of the friction elements allows the application of a clamping force in order to brake the vehicle and, once the actuator electric stops rotating its rotating shaft, the braking force gradually decreases until it becomes zero. The blocking configuration corresponds to an irreversible or self-locking type configuration of the clamping device in which the movement of the friction elements is not permitted. Thus, after the clamping force has been applied while the clamping device was in delivery configuration, it is advantageous to control, using the transformation means, a passage of the crown assembly into blocking configuration in order to to maintain the clamping force without having to request the electric actuator and, for example, without requiring electrical resources, which is particularly advantageous for parking braking.

The fact that the blocking of the output rotational movement of the planetary gear train takes place at the level of the delivery crown assembly is advantageous because if the electric actuator is actuated while the crown assembly is in the movement blocking configuration output rotation, the input rotation movement is nevertheless received by the epicyclic gear at the level of the planetary pinion and can be distributed between satellites and a planet carrier of the planetary gear which are movable in rotation even in the event of immobilization of the whole forming a crown. The risk of damaging parts of the clamping device, in particular the rotating shaft of the electric actuator, is therefore low.

The invention may also include one or more of the following optional features, taken alone or in combination.

The crown assembly comprises a first crown mounted on the frame so as to be fixed in rotation and movable in translation and a second crown mounted on the frame so as to be fixed in translation and movable in rotation around its main axis, the epicyclic gear train comprising satellites meshing with the planetary pinion, the first ring gear and the second ring gear. This is a simple and robust assembly allowing the transmission of the rotational movement of the output shaft of the electric actuator. We understand in particular that when the planetary pinion is rotated by the output shaft of the electric actuator, it in turn causes the satellites which mesh with it to rotate on themselves. This rotation of the satellites on themselves, due to the fact that they mesh with the first crown which is fixed in rotation, causes a rotation of the satellites around the axis of the planetary pinion which causes the rotation of the second crown with which they also mesh and therefore transmit the rotational movement to the conversion mechanism.

The means for transforming the crown assembly comprise means for moving the first crown in translation between a disengaged position in which the crown assembly is in its configuration for delivering the output rotational movement and a clutch position with the second crown in which the crown assembly is in its configuration for blocking the output rotational movement. This is a robust assembly allowing a simple transition from delivery of the output rotation movement to a configuration of blocking the output rotation movement and vice versa. For example, it is anticipated that the first crown will have clutch teeth intended to cooperate with clutch grooves provided on the second crown so as to immobilize it in rotation. When the first crown is in the interconnection position with the second crown, the crown assembly is therefore fixed in rotation. As indicated previously, the fact that the crown assembly is fixed in rotation does not limit the rotational mobility of the other elements of the planetary gear train, which limits the risk of damage to the clamping device and the electric actuator.

The first crown is made at least partly of a ferromagnetic material and the means for moving the first crown in translation comprise at least one solenoid intended to move the first crown between its disengaged position and its interconnection position with the second crown when it carries an electric current. Using a solenoid is a simple and reliable way to move the first ring gear in a controlled manner. By solenoid we understand any device consisting of a metal electrical wire wound regularly in a helix so as to form a coil which, when an electric current passes through it, produces a magnetic field. The strength of the magnetic field depends in particular on the intensity of the electric current. In addition, by varying the direction of flow of the electric current in the electric wire, it is possible to vary the direction of the magnetic field that is generated. For the purposes of the invention, by solenoid we also mean an electric coil or an electromagnet capable of generating a magnetic field when an electric current passes through them.

The means for moving the first crown in translation comprise an elastic return spring of the first crown towards its interlocking position with the second crown, the solenoid being intended to move the first crown in translation from its interlocking position with the second crown until 'to its disengaged position when an electric current passes through it. This embodiment is advantageous because the elastic return spring makes it possible to automatically position the first crown in the interconnection position with the second crown when the solenoid is not supplied with electricity. The blocking configuration of the output rotational movement of the ring assembly, in which the clamping device is said to be self-locking configuration, which is desired during parking braking, is thus obtained in a simple and economical manner. When a movement of the friction elements is desired, an electric current passes through the solenoid which thus generates a magnetic field which acts on the ferromagnetic material of the first crown so as to exert a force greater than the elastic return force of the spring so as to to move the first crown in translation from its interconnection position with the second crown to its disengaged position. As long as sufficient electrical current flows through the solenoid, the first ring gear remains in the disengaged position.

At least part of the first crown constitutes a permanent magnet and the solenoid, in cooperation with the permanent magnet, is intended to move the first crown from its interlocking position with the second crown to its disengaged position when it is traversed by an electric current in a first direction and to move the first ring gear from its disengaged position to its interconnection position with the second ring gear when an electric current passes through it in a second direction opposite the first direction. This embodiment is advantageous because it makes it possible to limit the number of parts used to produce the clamping device and therefore to limit its manufacturing cost and simplify its manufacturing. The fact that at least part of the first crown constitutes a permanent magnet allows the solenoid to attract or repel the first crown depending on the direction of the electric current passing through it. For example, when the electric current circulates in the solenoid in the first direction of circulation, the magnetic field generated pushes the permanent magnet of the first ring so as to move it in translation from the interconnected position with the second ring to the position disengaged. When the electric current circulates in the solenoid in the second direction of circulation, the magnetic field generated attracts the permanent magnet of the first crown so as to move it in translation from the disengaged position to the interconnection position with the second crown.

The means for moving the first ring in translation comprise first and second solenoids, the first solenoid being intended to move the first ring from its interconnected position with the second ring to its disengaged position when an electric current passes through it and the second solenoid being intended to move the first crown from its disengaged position to its interconnection position with the second crown when an electric current passes through it. This embodiment is advantageous because it makes it possible to control the position of the first crown in a simple and reliable manner. We understand that to carry out the movement of the first ring, it is preferable that only one of the solenoids has an electric current flowing through it at a given moment.

At least part of the first crown constitutes a permanent magnet intended, in cooperation with the frame, to move the first crown into the interconnection position with the second crown, the solenoid being intended to move the first crown from its interconnection position with the second crown in its disengaged position when an electric current passes through it. In this embodiment, the permanent magnet of the first crown cooperates with the frame in order to move the first crown into the interconnection position with the second crown. In other words, the permanent magnet of the first crown is attracted by the frame which allows the movement of the first crown. For this, depending on the embodiments, it is possible for the frame to be at least partly made of ferromagnetic material, for example iron or steel. This is advantageous because the crown assembly thus assumes its blocking configuration when no current flows through the solenoid, which is the case most of the time during parking braking. The blocking configuration of the crown assembly is thus obtained automatically without additional energy expenditure when the vehicle contact is interrupted.

The means for moving the first crown in translation further comprise at least one permanent magnet intended to move the first crown in translation into the interconnection position with the second crown, the solenoid being intended to move the first crown into the disengaged position when it is carried by an electric current. In this embodiment, the permanent magnet cooperates with the ferromagnetic material of the first crown in order to move the first crown into the interconnection position with the second crown. In other words, the permanent magnet attracts the first crown which allows it to move in translation. This is advantageous because the crown assembly thus assumes its blocking configuration when no current flows through the solenoid, which is the case most of the time during parking braking. The blocking configuration of the crown assembly is thus obtained automatically and without additional energy expenditure when the vehicle contact is interrupted.

The invention also relates to a braking system for a vehicle comprising a pair of friction elements intended to cooperate by friction with a disc, the braking system comprising a clamping device as described above arranged to bring the pair of friction elements towards two opposite faces of the disc in order to grip it.

The invention also relates to a vehicle comprising at least one braking system as described above.

Brief description of the figures

The invention will be better understood on reading the description which follows, given solely by way of non-limiting example and made with reference to the appended drawings in which:

there is a schematic top view of a vehicle equipped with a braking system according to the invention;

there is a schematic sectional view of a braking system to which the invention can be applied;

there is a sectional view of a part of a braking system according to the invention;

there is a sectional view of a part of the braking system according to the invention in which the crown assembly is in a configuration for delivering the output rotational movement;

there is a view similar to the in which the crown assembly is in a blocking configuration for the output rotational movement;

there is a perspective view of the assembly forming the crown of the ;

there is a perspective view of the assembly forming the crown of the ;

there is a schematic sectional view of a part of a clamping device according to a first embodiment of the invention, in which the crown assembly is shown in configuration for delivering the output rotational movement (A) or in output rotation movement blocking configuration (B); And

there is a schematic sectional view of a part of a clamping device according to a second embodiment of the invention, in which the crown assembly is shown in configuration for delivering the output rotational movement (A) or in output rotation movement blocking configuration (B).

there is a schematic sectional view of a part of a clamping device according to a third embodiment of the invention, in which the crown assembly is shown in configuration for delivering the output rotational movement (A) or in output rotation movement blocking configuration (B).

there is a schematic sectional view of a part of a clamping device according to a fourth embodiment of the invention, in which the crown assembly is shown in configuration for delivering the output rotational movement (A) or in output rotation movement blocking configuration (B).

there is a schematic sectional view of a part of a clamping device according to a fifth embodiment of the invention, in which the crown assembly is shown in configuration for delivering the output rotational movement (A) or in output rotation movement blocking configuration (B).

detailed description

We represented on the a motor vehicle 1 in which a braking system 2, of the electromechanical type, according to the invention, is arranged on at least two, advantageously on each of the four wheels 3.

It will be noted that the invention applies to any type of braking system 2, in particular those intended to equip motor vehicles of the tourism type, SUV (English acronym for “Sport Utility Vehicles”), two wheels (in particular motorcycles), planes, industrial vehicles chosen from vans, "heavy goods vehicles" - that is to say metros, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering machinery -, or other transport or handling vehicles. The invention also applies to non-motorized vehicles such as a trailer, a semi-trailer or a caravan.

We have schematized on the an example of a braking system 2 to which the invention, which will be described in more detail below, is applied. This braking system 2 is of the floating caliper disc type. It comprises at least two friction elements 4a, 4b intended to cooperate by friction respectively with two opposite faces of a disc 5, integral in rotation with a wheel 3 of the vehicle 1.

The braking system 2 is of the electromechanical type. By “braking system 2 of the electromechanical type”, we mean all types of braking systems 2 comprising at least one electric actuator 11 intended to bring the friction elements 4a, 4b closer together in order to laterally pinch the disc 5 secured to the wheel 3 of vehicle 1 to brake it.

The braking system 2 comprises a clamping device 7 provided with a floating caliper 8 carrying a member 9 for applying clamping force to one of the friction elements 4a. Note that, in a variant not shown, the invention also applies to a fixed caliper braking system. In this case, the clamping device 7 comprises two members 9 for applying force respectively to the two friction elements 4a, 4b.

The clamping device 7 is formed of a frame 10 comprising the electric actuator 11 on one side only and is formed of a yoke fixed relative to the vehicle 1 and the stirrup 8 which is movable relative to the yoke and arranged to bring the friction element 4b closer together once the friction element 4a is in contact with the disc 5. Such a clamping device 7 of the floating stirrup type makes it possible to use fewer electric actuators 11 and thus 'be more compact.

The electric actuator 11 provides the clamping force to the clamping device 7. It includes an output shaft 12 that rotates when the electric actuator 11 is actuated.

The clamping device 7 comprises a mechanism 13 for converting the rotational movement of the output shaft 12 of the electric actuator 11 into translational movement in order to allow a relative displacement movement between the friction elements 4a, 4b, of preferably in the rectilinear axial direction A. In the present case, the mechanism 13 for converting the rotational movement is of the ball screw type. It comprises a nut 14, receiving the rotational movement, coupled by balls 15 to a screw 16 delivering the translation movement to the member 9 for applying the clamping force. More particularly, the output shaft 12 is coupled with the nut 14 by a rotation speed reduction mechanism 17 intended to reduce the rotation speed of the output shaft 12 which is transmitted to the nut 14 and thus to increase the torque exerted.

The rotation speed reduction mechanism 17 comprises an epicyclic gear train comprising a planetary pinion 18 for receiving the rotational movement of the output shaft 12 of the electric actuator 11. Thus, a rotation of the output shaft 12 of the electric actuator 11 causes a rotation of the planetary pinion 18 of the planetary gear train. The planetary gear train also comprises an assembly 19 forming a crown for delivering the rotational movement of the output shaft 12 to the conversion mechanism 13. Thus, the rotational movement enters the reduction mechanism 17 at the planetary pinion 18 and exits at the crown assembly 19 and is transmitted to the mechanism 13 for converting the rotational movement into translational movement. The planetary gear train further comprises satellites 20 carried by a planet carrier 21, the satellites 20 meshing with the planetary pinion 18 and the assembly 19 forming a ring gear.

The crown assembly 19 comprises a first crown 22 mounted on the frame 10 so as to be fixed in rotation and movable in translation and a second crown 23 mounted on the frame 10 so as to be fixed in translation and movable in rotation around its main axis, corresponding in the present case to the axial rectilinear direction A. In the present case, the translational mobility of the first crown 22 is allowed by the presence of translation grooves 30 formed in the frame 10 in which are housed radial guides 31 of the first crown 22. The shape cooperation between the translation grooves 30 of the frame 10 and the radial guides 31 of the first crown 22 allows the translation of the first crown 22 and also ensures the immobility in rotation of this first crown 22.

The satellites 20 mesh with both the first crown 22 and the second crown 23. This is a simple and robust assembly allowing the transmission of the rotational movement of the output shaft 12 of the actuator 11 electric. We understand in particular that when the planetary pinion 18 is rotated by the output shaft 12 of the electric actuator 11, it in turn causes the satellites 20 which mesh with it to rotate on themselves. This rotation on themselves of the satellites 20, due to the fact that they mesh with the first crown 22 which is fixed in rotation, causes a rotation of the satellites 20 around the axis of the planetary pinion 18 which causes the rotation of the second crown 23 with which they also mesh. The second crown 23 being coupled with the conversion mechanism 13, its rotation causes the rotation of the nut 14 and therefore the translation of the screw 16 which itself causes the translation of the member 9 for applying tightening force in order to move the friction elements 4a, 4b and achieve braking.

In the present case, the first crown 22 is made at least partly of a ferromagnetic material. For example, the first crown 22 is made at least partly of iron, nickel, cobalt, neodymium or steel.

The clamping device 7 further comprises means for transforming the assembly 19 forming a crown between a configuration for delivering the output rotational movement (see Figures 4 and 6) and a configuration for blocking the output rotational movement (see figures 5 and 7).

The means for transforming the crown assembly 19 comprise means 25 for moving the first crown 22 in translation between a disengaged position (see Figures 4 and 6) in which the crown assembly 19 is in its delivery configuration of the crown. output rotational movement and a position of engagement with the second crown 23 (see Figures 5 and 7) in which the assembly 19 forming the crown is in its configuration for blocking the output rotational movement. The first crown 22 has, at its distal end edge, contiguous to the second crown, interlocking teeth 28 which, in the present case, extend regularly over the entire periphery of this end edge (see figures 6 and 7). These interlocking teeth 28 are intended to cooperate with interlocking grooves 29 provided at the level of the proximal end edge of the second crown 23 which is contiguous to the distal end edge of the first crown 22. Cooperation between the teeth 28 interlocking of the first crown 22 and the interlocking grooves 29 of the second allows, when the first crown 23 is in the interlocking position with the second crown 23, to prevent the rotation of the second crown 23 and therefore the transmission of movement rotation of the output shaft 12 of the electric actuator 11.

According to a first embodiment illustrated in Figures 3 to 8, the means 25 for moving in translation of the first crown 22 comprise a solenoid 26 intended to move the first crown 22 between its disengaged position and its interconnection position with the second crown 23 when an electric current passes through it. By solenoid within the meaning of the invention also means an electric coil or an electromagnet capable of generating a magnetic field when an electric current passes through them. The means 25 for moving in translation of the first crown 22 further comprise a spring 27 for elastic return of the first crown 22 towards its interconnection position with the second crown 23. The spring 27 bears at its proximal end on the frame 10 of the clamping device 7 and is subjected to compression at its distal end by the first crown 22 to which it is fixed (see ). This embodiment is advantageous because the elastic return spring 27 makes it possible to automatically position the first crown 22 in the interconnection position with the second crown 23 when the solenoid is not supplied with electricity. The configuration for blocking the output rotational movement of the crown assembly 19, in which the clamping device 7 is said to be a self-locking configuration, which is desired during parking braking, is thus obtained in a simple and economical manner.

An example of operation of the clamping device 7 according to the first embodiment of the invention is described below for use as a service brake.

According to this first embodiment, when the user drives the vehicle 1, the solenoid 26 is not passed by an electric current so that the force applied by the spring 27 on the proximal end of the first crown 22 is sufficient to maintain the first crown 22 in its interconnection position with the second crown 23 (see Figures 5, 7 and 8A). The assembly 19 forming a crown is thus in a blocking configuration for the output rotation movement. When the user of vehicle 1 wishes to use the service brake, he activates a braking member (not shown) and, consequently, an electronic control unit (not shown) controls the supply of electric current to the solenoid 26. This results in the generation of a magnetic field by the solenoid 26 which attracts the ferromagnetic material included in the first crown 22 with a force which is greater than the return force of the spring 27 so as to move the first crown 22 in translation according to the direction D from its interconnection position with the second ring 23 (see Figure 8A) to its disengaged position (see Figure 8B). Thus, the crown assembly 19 passes from its blocking configuration to its delivery configuration of the output rotational movement. The electronic control unit also controls the activation of the electric actuator 11 which, in the present case, comprises an electric motor, which causes the rotation of the output shaft 12. The speed of this rotation is reduced by the epicyclic gear train which transmits the reduced rotational movement to the conversion mechanism 13 so that the rotational movement is converted into translational movement and allows movement of the friction elements 4a, 4b so that they enclose disc 5 and perform braking. The electronic control unit controls a maintenance of the supply of electric current to the solenoid 26 for the entire duration of braking and the time necessary for a return to zero clamping force. Once the braking is completed, the electronic control unit orders an interruption of the electrical current supply to the solenoid 26 and the return force of the spring 27 then makes it possible to move the first crown 22 in translation in the direction C of its disengaged position (see Figure 8B) towards its interconnection position with the second crown 23 (see Figure 8A).

An example of operation of the clamping device 7 according to the first embodiment of the invention is described below for use as a parking brake.

When the user wishes to use the clamping device 7 as a parking brake, he activates a control member (not shown) of the parking brake. The electronic control unit then controls the supply of electric current to the solenoid 26 in the case where it was not already supplied with electric current, and, if it was already supplied with electric current, the control unit electronic control controls maintenance of this power supply. In response to this supply of electric current, the solenoid 26 generates a magnetic field so that the first crown 22 is moved in translation in direction D towards its disengaged position (see Figures 4, 6 and 8B), that is to say say that the assembly 19 forming a crown is in the delivery configuration of the output rotational movement. The electronic control unit also controls activation of the electric actuator 11 in order to apply the clamping force necessary for parking braking. Once this clamping force is reached, the electronic control unit controls the interruption of the supply of electric current to the solenoid 26 so that the force applied by the spring 27 becomes sufficient to move in translation according to the direction C the first crown 22 from its disengaged position to its interconnection position with the second crown 23 (see Figures 5, 7 and 8A). Thus, while a tightening force is applied by the tightening device 7, the first crown 22 passes from its disengaged position to its engaged position with the second crown 23, that is to say that the assembly 19 forming the crown goes from its configuration for delivering the output rotational movement to its configuration for blocking the output rotational movement. The second crown 23, which is coupled to the conversion mechanism 13 and which is blocked in rotation, therefore also blocks the rotation of the nut 14 of the conversion mechanism 13 so that the member 9 for applying clamping force does not can no longer return to its initial position. Thus, the clamping force is maintained automatically once the crown assembly 19 is in its exit movement blocking configuration and this without requiring the clamping device 7 to be supplied with electrical energy. When the user wishes to release the parking brake, he activates the parking brake control member and the electronic control unit controls the supply of electric current to the solenoid 26 so as to move the first crown 22 to the disengaged position as described previously. The crown assembly 19 is then in the delivery configuration of the sotie rotational movement and the relative movement between the elements 4a, 4b is again possible, so that the clamping force can be reduced until it becomes zero and the vehicle 1 which is no longer braked can then move.

A clamping device according to a second embodiment of the invention is described below, with reference to Figures 9A and 9B.

The second embodiment of the invention differs from the first embodiment only by the nature of the means 25 for moving in translation of the first crown 22. Indeed, in this second embodiment, the means 25 for moving do not include spring 27. The means 25 for moving in translation of the first crown 22 comprise first and second solenoids 26, the first solenoid 26a being intended to move the first crown 22 from its interlocking position with the second crown 23 to its disengaged position when an electric current passes through it and the second solenoid 26b is intended to move the first crown 22 from its disengaged position to its interconnection position with the second crown 23 when an electric current flows through it. The change in position of the first crown 22 is thus easily controlled by controlling the electric current supply to the first or second solenoid 26, 26b.

An example of operation of the clamping device 7 according to the second embodiment of the invention is described below for use as a service brake.

According to this second embodiment, when the user drives the vehicle 1, none of the first and second solenoids 26a, 26b is carried by an electric current. When the user of vehicle 1 wishes to use the service brake, he activates the braking member (not shown) and, consequently, the electronic control unit (not shown) controls the supply of current to the first solenoid 26a electric. This results in the generation of a magnetic field by the first solenoid 26a which attracts the ferromagnetic material included in the first crown 22 with a force which makes it possible to move the first crown 22 in translation in direction D from its interconnection position with the second crown 23 (see Figure 9A) to its disengaged position (see Figure 9B). Thus, the crown assembly 19 passes from its blocking configuration to its delivery configuration of the output rotational movement. The electronic control unit also controls the activation of the electric actuator 11 which, in the present case, comprises an electric motor, which causes the rotation of the output shaft 12. The speed of this rotation is reduced by the epicyclic gear train which transmits the reduced rotational movement to the conversion mechanism 13 so that the rotational movement is converted into translational movement and allows movement of the friction elements 4a, 4b so that they enclose disc 5 and perform braking. It is not necessary to supply the first solenoid 26a with electric current for the entire duration of braking. Indeed, once the first crown 22 is in the disengaged position, it remains in this position. According to a variant embodiment, once the braking is completed and the clamping force is zero, the electronic control unit controls the supply of electrical current to the second solenoid 26b in order to move the first crown 22 from its position disengaged (see Figure 9B) towards its interconnection position with the second crown 23 (see Figure 9A). According to another alternative embodiment, once braking is completed, the electronic control unit does not control a supply of electric current to the second solenoid 26b so that the second crown 22 remains in the disengaged position, that is to say that the crown assembly 19 remains in the delivery configuration of the output rotational movement. Thus, during the following service braking, it is not necessary to move the first crown 22 again since it is already in its disengaged position allowing transmission of the rotational movement and therefore movement of the elements 4a, 4b of friction.

An example of operation of the clamping device 7 according to the second embodiment of the invention is described below for use as a parking brake.

When the user wishes to use the clamping device 7 as a parking brake, he activates the control member (not shown) of the parking brake. The electronic control unit then controls the supply of electric current to the first solenoid 26a in the case where the first crown 22 was in the interconnection position with the second crown 23. In response to this supply of electric current, the first solenoid 26a generates a magnetic field so that the first crown 22 is moved in translation in direction D towards its disengaged position (see Figures 4, 6 and 9B), so that the assembly 19 forming crown is in the delivery configuration of the movement of output rotation. Once the first crown 22 has reached its disengaged position, the electronic control unit orders an interruption of the supply of electric current to the first solenoid 26a. Despite this interruption, the first crown remains in the disengaged position. The electronic control unit also controls activation of the electric actuator 11 in order to apply the clamping force necessary for parking braking. Once this clamping force is reached, the electronic control unit controls the supply of electric current to the second solenoid 26b so as to move the first crown 22 in translation in direction C from its disengaged position to its interconnected position with the second crown 23 (see Figures 5, 7 and 9A). Once the first crown 22 has reached its interconnection position with the second crown 23, the electronic control unit orders an interruption of the supply of electric current to the second solenoid 26b. Despite this interruption, the first crown 22 remains in the interconnection position with the second crown 23. Thus, while a tightening force is applied by the tightening device 7, the first crown 22 passes from its disengaged position to its disengaged position. interconnection with the second crown 23, that is to say that the crown assembly 19 passes from its configuration for delivering the output rotational movement to its configuration for blocking the output rotational movement. The second crown 23, which is coupled to the conversion mechanism 13 and which is blocked in rotation, therefore also blocks the rotation of the nut 14 of the conversion mechanism 13 so that the member 9 for applying clamping force does not can no longer return to its initial position. Thus, the clamping force is maintained once the crown assembly 19 is in its exit movement blocking configuration and this without requiring the clamping device 7 to be supplied with electrical energy. When the user wishes to release the parking brake, he activates the parking brake control member and the electronic control unit controls the supply of electric current to the first solenoid 26s so as to move the first crown 22 in translation in direction D in the disengaged position as described previously. The crown assembly 19 is then in the delivery configuration of the sotie rotational movement and the relative movement between the elements 4a, 4b is again possible, so that the clamping force can be reduced until it becomes zero and the vehicle 1, which is no longer braked, can then move.

A clamping device according to a third embodiment of the invention is described below, with reference to Figures 10A and 10B.

The third embodiment of the invention differs from the first embodiment only with regard to the points described below. According to the third embodiment, at least part of the first crown 22 constitutes a permanent magnet 32. Furthermore, according to this third embodiment, the solenoid 26, in cooperation with the permanent magnet 32, is intended to move the first crown 22 from its interconnection position with the second crown 23 to its disengaged position when an electric current passes through it in a first direction and to move the first crown 22 from its disengaged position to its interconnection position with the second crown 23 when an electric current passes through it in a second direction opposite to the first direction.

The operation of the clamping device 7 according to this third embodiment is similar to that which was described for the second embodiment. The only difference lies in the fact that in the second embodiment two solenoids are used to attract the first crown 22 and move it in translation between its disengaged and interconnection configurations with the second crown 23 whereas in the third embodiment one only solenoid is present but, thanks to the presence of the permanent magnet 32, it is possible to attract or repel the first crown 22 with this sole solenoid 26 depending on the direction in which the current circulates inside of the solenoid. Thus, when a passage of the assembly 19 forming a crown into the position for delivering the output rotational movement is desired, the electronic control unit controls the supply of the solenoid 26 with electric current in the first direction of circulation, causing thus the generation by the solenoid of a magnetic field which, in the present case, repels the permanent magnet 32 of the first crown 22 and therefore moves in translation in direction D the first crown 22 in the disengaged position (see Figure 10B) . When a passage of the assembly 19 forming a crown into the position of blocking the output rotational movement is desired, the electronic control unit controls the supply of the solenoid 26 with electric current in the second direction of circulation, thus causing the generation by the solenoid of a magnetic field which, in the present case, attracts the permanent magnet 32 of the first crown 22 and therefore moves in translation in direction C the first crown 22 into the interconnection position with the second crown 23 ( see figure 10B).

A clamping device according to a fourth embodiment of the invention is described below, with reference to Figures 11A and 11B.

The fourth embodiment of the invention differs from the first embodiment only with regard to the points described below. In this fourth embodiment, at least part of the first crown 22 constitutes a permanent magnet 32 intended, in cooperation with the frame 10, to move the first crown into the interconnection position with the second crown 23 (see Figure 11A). Thus, the cooperation between the permanent magnet 32 and the frame 10 plays the role of the spring 27 described for the first embodiment. The solenoid 26 is always intended to move the first crown 22 from its interconnection position with the second crown 23 to its disengaged position (see Figure 11B) when an electric current passes through it.

Thus, the operation of the clamping device 7 according to this fourth embodiment is similar to that which was described for the first embodiment. The only difference lies in the fact that in the first embodiment a spring 27 is used to move the first crown 22 in translation towards its interconnection configuration with the second crown 23 whereas in the fourth embodiment it is the permanent magnet 32, in cooperation with the frame 10, which allows this movement. Thus, when a passage of the assembly 19 forming a crown into the position for delivering the output rotational movement is desired, the electronic control unit controls the supply of the solenoid 26 with electric current, thus causing the generation by the solenoid of a magnetic field which, in the present case, attracts the ferromagnetic material of the first ring 22 with a force greater than that of the magnetic attraction between the permanent magnet 32 and the frame 10. This results in a translational movement in direction D of the first crown 22 in the disengaged position (see Figure 11B). It is necessary to maintain the supply of electric current to the solenoid 26 as long as maintaining the delivery configuration of the output rotational movement is desired. When a passage of the assembly 19 forming a crown into the position of blocking the output rotational movement is desired, the electronic control unit controls the interruption of the supply of the solenoid 26 with electric current so that the cooperation between the permanent magnet 32 and the frame make it possible to move in translation in direction C the first ring 22 in the interconnection position with the second ring 23 (see Figure 11A).

A clamping device according to a fifth embodiment of the invention is described below, with reference to Figures 12A and 12B.

The fifth embodiment of the invention differs from the first embodiment only with regard to the points described below. In place of the spring 27, the means 25 for moving the first crown 22 in translation further comprise at least one permanent magnet 33 intended to move the first crown in translation into the interconnection position with the second crown 23 (see Figure 12A) . Thus, the cooperation between the permanent magnet 33 and the ferromagnetic material of the first crown plays the role of the spring 27 described for the first embodiment. According to an alternative embodiment, the permanent magnet 33 is integrated into the frame 10 in order to make the clamping device 7 more compact. The solenoid 26 is always intended to move the first crown 22 from its interconnected position with the second crown 23 to its disengaged position (see Figure 12B) when an electric current passes through it.

Thus, the operation of the clamping device 7 according to this fifth embodiment is similar to that which was described for the first embodiment. The only difference lies in the fact that in the first embodiment a spring 27 is used to move the first crown 22 in translation towards its interconnection configuration with the second crown 23 whereas in the fourth embodiment it is the permanent magnet 33, in cooperation with the first crown 22, which allows this movement. Thus, when a passage of the assembly 19 forming a crown into the position for delivering the output rotational movement is desired, the electronic control unit controls the supply of the solenoid 26 with electric current, thus causing the generation by the solenoid 26 of a magnetic field which, in the present case, attracts the ferromagnetic material of the first crown 22 with a greater effort than that of the magnetic attraction between the permanent magnet 33 and the ferromagnetic material of the first crown 22. It this results in a translational movement in direction D of the first crown 22 in the disengaged position (see Figure 12B). It is necessary to maintain the supply of electric current to the solenoid 26 as long as maintaining the delivery configuration of the output rotational movement is desired. When a passage of the assembly 19 forming a crown into the position of blocking the output rotational movement is desired, the electronic control unit controls the interruption of the supply of the solenoid 26 with electric current so that the cooperation between the permanent magnet 33 and the first crown 22 make it possible to move in translation in direction C the first crown 22 in the interconnection position with the second crown 23 (see Figure 12A).

The invention is not limited to the embodiments presented and other embodiments will be clearly apparent to those skilled in the art. Thus, the embodiments and variants can be combined with each other without departing from the scope of the invention.

Reference list

1: motor vehicle
2: braking system
3: wheel
4a, 4b: friction elements
5: disk
7: clamping device
8: stirrup
9: clamping force application member
10: frame
11: electric actuator
12: output shaft of the electric actuator
13: mechanism for converting the rotational movement of the output shaft
14: nut
15: marbles
16: screw
17: rotation speed reduction mechanism
18: planetary gear
19: crown assembly
20: satellite
21: satellite carrier
22: first crown
23: second crown
25: means for moving the first crown in translation
26: solenoid
26a: first solenoid
26b: second solenoid
27: spring
28: clutch tooth
29: clutch groove
30: translation groove
31: radial guide
32: permanent magnet of the first crown
33: permanent magnet of the translational movement means of the first crown

Claims (11)

Clamping device (7) for a braking system (2) intended to exert a relative movement between friction elements (4a, 4b) and comprising a frame (10) supporting an electric actuator (11) intended to provide the clamping force and a rotation speed reduction mechanism (17) coupling an output shaft (12) of the electric actuator (11) to a mechanism (13) for converting the rotational movement of the output shaft (12) into translational movement in order to allow the relative displacement movement between the friction elements (4a, 4b),
in which the rotation speed reduction mechanism (17) comprises an epicyclic gear train comprising:
- a planetary pinion (18) for receiving the rotational movement of the output shaft (12) of the electric actuator (11), and
- an assembly (19) forming a crown for delivering the output rotational movement to the conversion mechanism (13),
characterized in that the clamping device (7) comprises means for transforming the crown assembly (19) between a configuration for delivering the output rotational movement and a configuration for blocking the output rotational movement. Clamping device (7) according to claim 1, in which the crown assembly (19) comprises a first crown (22) mounted on the frame (10) so as to be fixed in rotation and movable in translation and a second crown (23) mounted on the frame (10) so as to be fixed in translation and mobile in rotation around its main axis, the planetary gear train comprising satellites (20) meshing with the planetary pinion (18), the first crown (22) ) and the second crown (23). Clamping device (7) according to claim 2, in which the means for transforming the crown assembly comprise means (25) for moving the first crown (22) in translation between a disengaged position in which the assembly ( 19) forming the crown is in its configuration for delivering the output rotational movement and a position of engagement with the second crown (23) in which the assembly (19) forming the crown is in its configuration for blocking the output rotational movement . Clamping device (7) according to claim 3, in which the first crown (22) is made at least partly of a ferromagnetic material and the means (25) for moving in translation of the first crown (22) comprise at least one solenoid (26) intended to move the first crown (22) between its disengaged position and its interconnection position with the second crown (23) when an electric current passes through it. Clamping device (7) according to claim 4, in which the means (25) for moving the first crown (22) in translation comprise a spring (27) for elastically returning the first crown (22) towards its interconnected position with the second crown (23), the solenoid (26) being intended to move the first crown (22) in translation from its interconnected position with the second crown (23) to its disengaged position when a current passes through it electric. Clamping device (7) according to claim 4, in which at least part of the first crown (22) constitutes a permanent magnet (32) and the solenoid (26), in cooperation with the permanent magnet (32), is intended to move the first crown (22) from its interconnected position with the second crown (23) to its disengaged position when an electric current passes through it in a first direction and to move the first crown (22) from its position disengaged in its interconnection position with the second ring (23) when an electric current flows through it in a second direction opposite to the first direction. Clamping device (7) according to claim 4, in which the means (25) for moving in translation of the first crown (22) comprise first and second solenoids, the first solenoid (26a) being intended to move the first crown ( 22) from its interconnection position with the second crown (23) to its disengaged position when an electric current passes through it and the second solenoid (26b) being intended to move the first crown from its disengaged position to its interconnection position with the second crown (23) when an electric current passes through it. Clamping device (7) according to claim 4, in which at least part of the first crown (22) constitutes a permanent magnet (32) intended, in cooperation with the frame (10), to move the first crown (22) in the interconnection position with the second crown (23), the solenoid (26) being intended to move the first crown (22) from its interconnection position with the second crown (23) to its disengaged position when it is traversed by a Electric power. Clamping device (7) according to claim 4, in which the means (25) for moving the first crown (22) in translation further comprise at least one permanent magnet (33) intended to move the first crown (22) in translation. ) in the interconnection position with the second crown (23), the solenoid (26) being intended to move the first crown (22) into the disengaged position when an electric current passes through it. Braking system (2) for a vehicle (1) comprising a pair of friction elements (4a, 4b) intended to cooperate by friction with a disc (5), characterized in that it comprises a clamping device (7). according to any one of the preceding claims arranged to bring the pair of friction elements (4a, 4b) together towards two opposite faces of the disc (5) in order to grip it. Vehicle (1) characterized in that it comprises at least one braking system (2) according to the preceding claim.