Clamping device for brake system with integrated locking device

Abstract

The invention relates to a clamping device (1) for a brake system for applying a relative displacement between friction elements. The clamping device comprises a first actuator (2) for providing a clamping force to the friction element and comprising a rotor (3); and a locking device (4, 4 ', 5, 6, 7, 8) for locking the rotation of the rotor (3). The invention also relates to a brake system comprising such a clamping device and a braking method of such a clamping device.

Description

[0001] The present invention relates to the field of braking systems for vehicles, and more particularly to a non-self-locking braking system of the electromechanical type.

[0002] Braking systems for vehicles, particularly motor vehicles, generally include mechanical clamping devices which in particular include friction elements such as brake linings. These friction elements are connected to an actuator which is capable of pulling a pair of such friction elements together (towards each other) in the direction of two opposite faces of a disc fixed to a vehicle wheel. This method causes the friction elements to clamp the disc and thus to brake the vehicle by friction between the friction elements and the disc, or to move them apart to stop braking.

[0003] In the case of a braking system of the electromechanical type, the mechanical clamping device includes at least one electric actuator, such as an electric motor provided with a rotary output shaft. The actuation of this electric motor is capable both of braking the vehicle during travel and of ensuring the parking brake function when the vehicle remains stationary for a possibly very long time. In other words, contrary to conventional braking systems which ensure the parking brake by a dedicated system, this braking system must be able to maintain the clamping force exerted by the friction elements on the disc in order to ensure an effective and reliable parking brake. For this purpose, there currently exist braking systems of the electromechanical type called "self-locking", but these systems are complex to implement and generally prove to be expensive. Alternatively, there exist so-called "non-self-locking" electromechanical braking systems in which the electric motor is of the reversible type. In other words, the rotation of the electric motor in a first direction ultimately causes the disc to be clamped by the friction elements, while the actuation of the same electric motor in the opposite direction of rotation ultimately causes the disc to be released by the friction elements. In order to ensure the necessary locking of the friction device when the parking brake function is required, it is known that for these non-self-locking systems, a second electric motor with its own power train is added, the purpose of which is to actuate the parking brake. However, the addition of such a second motor is bulky and thus increases the space required for the electromagnetic braking device within the vehicle, which is contrary to the current problems of motor vehicle manufacturers who seek to optimize the minimum space of the vehicle. In addition to its volume, such a device is more expensive and complex to implement in terms of the necessary electrical connections between its different elements and the electronic control unit and in terms of the drive of the two motors by the electronic control unit.

[0004] The object of the present invention is in particular to overcome all the above-mentioned drawbacks by proposing a clamping device for a braking system which is compact, easy to implement and inexpensive.

[0005] To this end, the subject of the present invention is a clamping device for a braking system for applying a relative displacement (movement) between the friction elements of the braking system, the clamping device comprising:

[0006] - A first actuator of the electric motor type, which includes a rotor and is used to provide a clamping force to a friction element through the rotation of the rotor,

[0007] - A locking system for locking the rotation of the rotor,

[0008] Characterized in that the locking system includes:

[0009] - A first locking device and a second locking device with complementary shapes, the first locking device is located on the outer surface of the rotor, and the second locking device is located opposite the rotor,

[0010] - A second actuator of the electric motor type, which is configured to apply a relative displacement (movement) between the first locking device and the second locking device so that they cooperate with each other to lock the rotation of the rotor.

[0011] Therefore, due to the close positioning arrangement of the two electric actuators (usually also called "electric motors") of the device of the present invention, and the indirect locking effect of the second actuator on the first actuator, it is possible to ensure that the friction element is locked in the position of clamping the disc, and at the same time has a compact and easy-to-implement clamping device. Therefore, the parking brake function is ensured without overly affecting the space required in the vehicle, because the entire system for locking the rotation of the rotor can be positioned as close as possible to the first electric actuator. In addition, considering this proximity, the torque required to lock the rotation of the rotor of the first electric actuator does not need to be very large, which allows the use of a second actuator with a smaller size and lower characteristics (power, usage intensity). Therefore, the space required for the entire device is further reduced.

[0012] The complementarity of the shapes of the first locking device and the second locking device enables them to cooperate with each other when they come into contact under the action of the relative displacement generated (applied) by the second actuator. The term "cooperate" refers to a rigid (firm) and reversible engagement (assembly) between the first locking device and the second locking device to prevent any rotation of the rotor of the first actuator. In addition, when the movement of the vehicle is required again, the cooperation between the first device and the second device must be able to be released. This conversion between the engagement and disengagement of the first locking device and the second locking device must be able to be repeated reliably over time. For this purpose, any locking device known to those skilled in the art that meets the above criteria can be considered. As a non-limiting example, it can involve the cooperation between a pin and a hole for accommodating the pin, two tenons, a pin and a groove, a pin and a mortise, teeth, a groove and a tongue, etc.

[0013] Advantageously, the first actuator provides a clamping force to the friction element through the rotation of the rotor in a first rotation direction, and the locking system locks the rotation of the rotor in a second rotation direction opposite to the first rotation direction.

[0014] To provide better reactivity in the rotational locking of the rotor of the first actuator, the locking system further includes a rack, which includes second locking means on one of its faces facing the rotor.

[0015] To obtain the flexibility of the device, the locking system further includes two stoppers facing each other, and the rack is movably mounted between the two stoppers.

[0016] Advantageously, the locking system further includes a cam, which contacts the rack and is configured to allow a first relative movement of the rack relative to the rotor of the first actuator, and the cam is rotated (turned) by a second actuator.

[0017] To ensure the repeatability of the clamping device, the device further includes a return device for the rack, which is configured to allow a second relative movement of the rack relative to the rotor of the first actuator in a direction opposite to the first relative movement.

[0018] Advantageously, the first locking means and the second locking means include teeth with complementary shapes.

[0019] To provide high reactivity (responsiveness) in the rotational locking of the rotor of the first actuator, the first locking means are radially distributed over the whole or part of the circumference of the outer surface of the rotor, preferably over the whole circumference of the outer surface of the rotor.

[0020] Advantageously, the first actuator and / or the second actuator is a brushless DC motor.

[0021] The present invention also relates to a braking system, which includes a clamping device as described in any one of the foregoing variants, an electronic control unit, and a housing, and the first actuator, the second actuator, and the electronic control unit are located inside the housing.

[0022] The present invention also relates to a braking method for a clamping device as described in any one of the foregoing variants, and the braking method includes the following steps:

[0023] - Energize the first actuator, and the rotor of the first actuator rotates to provide a clamping force to the friction element.

[0024] - Reduce the rotational speed of the rotor.

[0025] - Energize the second actuator to apply a relative displacement (movement) between the first locking means and the second locking means so that they cooperate with each other to lock the rotation of the rotor.

[0026] - Disconnect the power supply of the two actuators.

[0027] Advantageously, the rotational speed of the second actuator is between 1 - 2 rpm.

[0028] Advantageously, energizing the second actuator causes the cam to rotate until the teeth distributed on the rack come into contact with the teeth radially distributed on the outer surface of the rotor of the first actuator. Description of the Drawings

[0029] The present invention will be better understood by reading the following description given by way of example only and with reference to the accompanying drawings, in which:

[0030] Figure 1 is a schematic view showing an embodiment of the device according to the present invention,

[0031] Figure 2 is a schematic view showing an alternative embodiment of the embodiment shown in 1,

[0032] Figure 3 is a set of schematic views ( Figure 3a , 3b and 3c), showing the operation of the device according to the embodiment shown in 1. Detailed Description

[0033] Figures 1 to 3c shows a clamping device according to a first embodiment ( Figure 1 and Figures 3a to 3c ) and according to a variant embodiment ( Figure 2 ), the clamping device being designated by the general reference numeral 1.

[0034] According to this first embodiment and its variants, but also according to embodiments and variants not shown, a clamping device 1 for a braking system, for applying a relative displacement (movement) between the friction elements of said braking system, comprises:

[0035] - a first actuator 2 of the brushless direct current (DC) type, comprising a rotor 3 for providing a clamping force to a friction element (not shown);

[0036] - a locking system for locking the rotation of the rotor 3, which comprises:

[0037] - a first locking device and a second locking device having complementary shapes, the first locking device being located on the outer surface of the rotor and the second locking device being located opposite the rotor,

[0038] - a second actuator of the electric motor type, which is configured to apply a relative displacement (movement) between the first locking device and the second locking device such that the first locking device and the second locking device cooperate with each other to lock the rotation of the rotor 3;

[0039] According to as Figures 1 to 3cIn the first embodiment and its variants as shown, the first locking device includes teeth 5 radially distributed on the outer surface of the rotor 3, and the second locking device includes teeth 8 distributed on the surface of the rack 6 that faces the rotor 3. The teeth 5 have a shape complementary to that of the teeth 8. The teeth 5 of the first locking device are distributed over a part ( Figure 1 ) or all ( Figure 2 ) of the circumference of the rotor 3. Distributing (the teeth 5) over the entire circumference of the rotor 3 enables the rotational locking of the rotor 3 to be more responsive because the likelihood of the rapid engagement of the teeth 5 and the teeth 8 is greater.

[0040] Still according to the first embodiment and its variants, the locking system further includes:

[0041] - A rack 6 provided with teeth 8 on one of its faces facing the rotor 3,

[0042] - Two stoppers 4 and 4' facing each other, with the rack 6 movably mounted between the two stoppers 4 and 4',

[0043] - A cam 7 that contacts the rack 6 and is configured to allow a first relative movement of the rack 6 relative to the rotor 3 of the first actuator 2. The rotation of the cam 7 is directly generated by the second actuator.

[0044] Thus, the clamping device 1 according to the present invention includes a first brushless DC actuator 2, which is known to those skilled in the art, and the actuation of the first brushless DC actuator 2 transmits a clamping force to the friction element via a power train (not shown). Consequently, the latter clamps a disc fixed to a vehicle wheel, thereby generating braking of the vehicle. The first actuator 2 includes a rotor 3 and a stator (not shown). The outer surface of the rotor 3 is provided with radially distributed teeth 5 over a part ( Figure 1 ) or all ( Figure 2 ) of its circumference. The shape of these teeth 5 is configured to be complementary to the shape of the teeth 8 of the rack 6. Thus, when these teeth 5 and 8 interact, the rotational locking of the rotor 3 of the first actuator 2 is ensured.

[0045] This will be described in more detail as Figure 1 and 3aThe device shown in FIGS. 1 to 3c. The purpose of the entire locking system is to ensure the rotational locking of the rotor 3 of the first actuator 2 when the vehicle needs to be parked stationary. To this end, they include a rack 6 which has teeth 8 on its face facing the rotor 3, the shape of the teeth 8 being complementary to the teeth 5 located on the rotor 3. The rack 6 is movably mounted between two stops 4 and 4' which are arranged opposite one another. In other words, the rack 6 is restricted to translate between the lower stop 4 and the upper stop 4'. The locking device also includes a cam 7 which is in contact with the said rack 6. More specifically, the cam 7 is in direct and continuous contact with the face of the rack 6 opposite the face facing the rotor 3. Finally, these locking devices include a second actuator (not shown) which is intended to rotate the cam 7 via a power train (not shown). This second actuator is preferably a DC motor, the dimensions and characteristics (power, operating voltage) of which are smaller than the dimensions and characteristics of the first actuator 2 of the same type.

[0046] The operation of the clamping device 1 when the vehicle needs to be parked stationary will be described below.

[0047] - In a first configuration ( Figure 3a ), directly in accordance with an instruction from the user who wishes to actuate the parking brake of the vehicle, the first actuator 2 is energized and performs a rotation (the direction of which is shown by the arrow R) in order to transmit a clamping force to the friction element. At this stage, the rack 6 is located opposite the rotor 3 such that the teeth 8 of the rack 6 and the teeth 5 of the rotor 3 do not come into contact and thus do not interfere with the rotation of the rotor 3. In this first configuration, the rack 6 rests on the lowest stop 4.

[0048] - In a second configuration ( Figure 3b ), when the clamping force transmitted under the action of the first actuator 2 is sufficient or about to be sufficient to ensure the safe stationary parking of the vehicle, the second actuator is energized, thereby causing the cam 7 to rotate. This rotation of the cam 7 in turn drives the rack 6 to translate towards the rotor 3 of the first actuator 2. The teeth 8 on the rack 6 and the teeth 5 on the rotor 3 (the shapes of which are complementary) approach each other until they come into contact ( Figure 3c ), thereby fixing the rotor 3 and the rack 6. When the first actuator stops being energized, the first actuator naturally rotates in the opposite direction under the action of the resultant force of the friction element. Since, at this stage, the rack fixed to the rotor 3 is moved until it comes into contact with the upper stop 4', this rotation of the rotor 3 in the opposite direction is prevented by the locking device. Thus, the movement of the rack 6 and thus the rotation of the rotor 3 are prohibited, so that the clamping force transmitted to the friction element is maintained without the need for continuous power supply to either of the actuators.

[0049] In a variant not shown, the device advantageously includes a return device for the rack 6, so that when the cam no longer exerts sufficient pressure on the rack, it is possible to force the rack 6 to return to its initial position (where the teeth 8 and 5 are spaced apart from each other), which can ensure the repeatability of the clamping device.

[0050] The braking method implemented by the device according to the invention operates as follows.

[0051] When stationary parking of the vehicle is required, the first actuator 2 is energized to provide a clamping force to the friction element.

[0052] Then, the rotational speed of the rotor 3 of the first actuator 2 is reduced.

[0053] The second actuator is energized to rotate the cam 7 until the tooth 8 on the rack 6 contacts the tooth 5 radially distributed over the whole or part of the circumference of the outer surface of the rotor 3 of the first actuator 2.

[0054] Finally, both electric motors are de-energized (switched off).

[0055] Advantageously, the clamping device 1 according to one of the embodiments or one of its possible variants is located inside a housing and, together with said housing and the electronic control unit, forms a braking system according to the invention.

[0056] The invention is not limited to the described embodiments and other embodiments will be obvious to a person skilled in the art. As an example, an embodiment not shown can be envisaged, in which the rack is mounted fixed vertically within the device. Thus, such a device does not require the presence of a stop. In another embodiment not shown, the second locking device is distributed over the cam and, when the cam is rotated by the second actuator, the second locking device comes into contact with the first locking device. Thus, such a device does not require the presence of a stop and a rack.

[0057] List of references

[0058] 1: Clamping device

[0059] 2: First actuator of the electric motor type

[0060] 3: Rotor

[0061] 4: Lower stop

[0062] 4': Upper stop

[0063] 5: Tooth of the first locking device

[0064] 6: Rack

[0065] 7: Cam

[0066] 8: Tooth of the second locking device

[0067] R: The rotation direction of the rotor 3.

Claims

1. A clamping device (1) for a braking system, which is used to apply a relative displacement between friction elements of the braking system, the clamping device comprises: - a first actuator (2) of the electric motor type, which includes a rotor (3) and is used to provide a clamping force to the friction elements through the rotation of the rotor (3), - a locking system (4, 4', 5, 6, 7, 8) for locking the rotation of the rotor (3), characterized in that the locking system (4, 4', 5, 6, 7, 8) comprises: - a first locking device and a second locking device with complementary shapes, the first locking device is located on the outer surface of the rotor, and the second locking device is located opposite to the rotor, - a second actuator of the electric motor type, which is arranged to apply a relative displacement between the first locking device and the second locking device so that the first locking device and the second locking device cooperate with each other to lock the rotation of the rotor (3).

2. The device (1) according to the previous claim, wherein, the first actuator provides a clamping force to the friction elements through the rotation of the rotor (3) in a first rotation direction, and the locking system locks the rotation of the rotor (3) in a second rotation direction opposite to the first rotation direction.

3. The device (1) according to any one of the preceding claims, wherein, the locking system further comprises a rack (6), and the rack (6) comprises the second locking device on one of its faces facing the rotor.

4. The device (1) according to the preceding claim, wherein, the locking system further comprises two stoppers (4, 4') facing each other, and the rack (6) is movably mounted between the two stoppers (4).

5. The device (1) according to claim 3 or 4, wherein, the locking system further comprises a cam (7), the cam (7) contacts the rack (6) and is arranged to allow a first relative movement of the rack (6) relative to the rotor (3) of the first actuator (2), and the cam is rotated by the second actuator.

6. The device (1) according to any one of claims 3 to 5, which further comprises a return device for the rack (6), the return device is arranged to allow a second relative movement of the rack (6) relative to the rotor (3) of the first actuator (2) in a direction opposite to the first relative movement.

7. The device (1) according to any one of claims 3 to 6, wherein, the first locking device and the second locking device comprise teeth (5, 8) with complementary shapes.

8. The device (1) according to any one of the preceding claims, wherein, the first locking devices are radially distributed on the whole or part of the circumference of the outer surface of the rotor (3), preferably on the whole circumference of the outer surface of the rotor.

9. The device (1) according to any one of the preceding claims, wherein, the first actuator and / or the second actuator is a brushless DC motor.

10. A braking system, the braking system comprising a clamping device (1) according to any one of the preceding claims, an electronic control unit and a housing, the first actuator (2), the second actuator and the electronic control unit being located within the housing.

11. A braking method for a clamping device (1) according to any one of claims 1 to 8, the braking method comprising the steps of: - energizing a first actuator (2), the rotor (3) of the first actuator rotating to provide a clamping force to a friction element, - reducing the rotational speed of the rotor (3), - energizing a second actuator to apply a relative displacement between a first locking device and a second locking device such that the first locking device and the second locking device cooperate with each other to lock the rotation of the rotor (3), - disconnecting the power supply of the two actuators.

12. The method according to the previous claim, wherein the rotational speed of the second actuator is between 1 rpm and 2 rpm.

13. The method according to claim 11 or 12, wherein energizing the second actuator causes the cam (7) to rotate until the teeth (8) distributed on the rack (6) contact the teeth (5) radially distributed on the outer surface of the rotor (3) of the first actuator (2).

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