DEVICE FOR BRAKE SYSTEM AND ASSOCIATED CONTROL METHOD

Abstract

The invention relates in particular to a force measurement device for a braking system comprising a motor (1) for rotating a gear reduction device (3, 4, 5, 8), an input shaft (2), and an output shaft (6). The device includes a first sensor (10), positioned upstream of said gear train so as to measure the angular rotation of said input shaft, a second sensor (20), positioned downstream of said gear train so as to measure the angular rotation of said output shaft, at least one elastically deformable element (7), positioned between said input shaft and said output shaft, and a calculation module (30) for calculating a torque (T) transmitted by the reduction device at a given instant, based on the angular rotation data transmitted at said given instant by said first and second sensors, said stiffness of the elastically deformable element, and the reduction coefficient of said reduction device.Figure for the abbreviation: [Fig.1].

Description

Title of the invention: DEVICE FOR BRAKE SYSTEM AND ASSOCIATED CONTROL METHOD FIELD OF INVENTION

[0001] The present invention relates in particular to a device for controlling operational parameters in a transmission system to optimize a braking system, allowing action on the control law of the braking system in real time.

[0002] It also relates to a braking system equipped with such a device and a method for implementing such a device.

[0003] The field of the invention is that of braking systems, in particular for automobiles.

[0004] The invention proposes a solution aimed at improving the performance of brake systems in the event of changes in the behavior of the elements of this system, for example in the event of changes in temperature, climatic conditions or wear.

[0005] PRIORITY OF THE TECHNOLOGY

[0006] In a vehicle, particularly a road vehicle, braking systems are becoming increasingly efficient and their development involves highly precise control laws.

[0007] In particular, climatic conditions can have consequences on the accuracy of brake operation, and techniques have been developed to take into account these effects of climatic conditions in order to compensate for possible losses of accuracy in vehicle braking.

[0008] All techniques implemented in vehicles must ensure, with greater safety, the stopping or deceleration of the vehicle in all scenarios or conditions of use of the braking system (in operation, parking, VDC, ABS). Some techniques use a Force / Brake torque distribution profile for each brake: under these conditions, it is relevant to implement a force sensor to meet the profile tracking requirements of the braking system. Torque sensors are generally expensive and it is not straightforward to implement them in braking systems.

[0009] The invention proposes an alternative solution to known systems which allows real-time control of the braking system when it is activated in order to act on the control law, to optimize braking performance. Description of the invention

[0010] According to a first aspect of the invention, at least one of the aforementioned goals is achieved with a force measurement device for a brake system comprising a motor for rotating a gear reduction device having, for applying a braking force to at least one brake pad, at least one gear train of one or more stages of gear pinions (which may be internally or externally toothed) having a reduction coefficient ranging from one to two hundred and fifty, in particular of at least twenty and / or at most fifty, said system having an input shaft, arranged to be driven in rotation by said motor according to a control law and to drive an output shaft via said gear train.

[0011] In accordance with the invention, said braking system device is remarkable in that it comprises: - a first sensor, positioned upstream of said gear train so as to measure the angular rotation of said input shaft between a rest position where the motor does not rotate the input shaft and an driven position where the motor rotates the input shaft, - a second sensor, positioned downstream of said gear train so as to measure the angular rotation of said output shaft between a rest position where the output shaft is not driven in rotation and an actuation position where the reduction device drives the output shaft in rotation, in that said reducing device comprises at least one elastically deformable element, positioned between said input shaft and said output shaft of the reducing device so as to be elastically deformed by a torque transmitted from the input shaft to the output shaft, said elastically deformable element having a stiffness, and in that it includes a calculation module for a torque transmitted by the reducing device at a given instant, from the angular rotation data transmitted at said given instant by said first and second sensors, of said stiffness of the elastically deformable element and of the reduction coefficient of said reducing device.

[0012] Thus implemented, the device makes it possible to determine the output torque of the transmission system, which allows for adjustment of the control law of the braking system, which in turn affects the operation of the motor. This notably overcomes certain shortcomings of existing systems which, in order to adjust the control law of the braking system, monitor the current: this is not always sufficient to achieve optimal performance, because the operating conditions of the transmission components can vary (temperature, humidity, etc.) and the control law does not sufficiently take into account the effects of these conditions on the transmission components. By taking into account the actual torque transmitted by the device, it is possible to adjust the control law of real-time control improves braking, because the actual braking effort required can be adjusted by knowing the actual torque.

[0013] Advantageously, the elastically deformable element is interposed between two coaxial parts of the reducer, one of which drives the other in rotation after compensating for angular backlash between them. This angular compensation is achieved partially or exclusively by compression of the elastically deformable element between two bearing surfaces supported by the coaxial parts. In such an embodiment, the elastically deformable element is typically deformed only in compression.

[0014] Preferably, the elastically deformable element is interposed between two coaxial gears which belong to two different gear stages within the reducer, and one of which drives the other in rotation after compensating for an angular backlash producing a deformation of said elastically deformable element.

[0015] Preferably, the reducing device comprises one or more stages whose shafts are mounted in the same structure forming a transmission cartridge, and the elastically deformable element and / or the second sensor is mounted on a shaft which is driven by said cartridge.

[0016] According to one embodiment, the electric motor is of a vector type incorporating an angular position sensor which is also used as the first sensor, in particular a brushless direct current (DC) sensor. According to another embodiment, said first sensor and said second sensor are position sensors of the same technology, preferably magnetoresistive sensors and in particular giant magnetoresistance (GMR) sensors.

[0017] Advantageously, the brake system device according to the invention comprises at least two elastically deformable elements, said at least two elastically deformable elements having different stiffnesses.

[0018] Preferably, said at least two deformable elements have the same shape and dimensions. Thus manufactured, the elements are interchangeable with other elastically deformable elements having different stiffnesses.

[0019] Preferably, according to an advantageous embodiment, the motor produces a torque of at least 0.5 Nm and less than 5 Nm, and for example of 1 Nm, and a reduction device having a reduction ratio between 20 and 60, and for example between 30 and 50. For such a configuration, said at least one elastic element is made of elastomer, for example of the EPDM type. By way of example, such an elastically deformable element may have the shape of an angular sector taken from an annular seal of rectangular cross-section, a sector whose external dimensions are, for example, at least 3 mm or even 4 mm and by For example, a thickness of at most 10 mm or even 7 mm; or a roughly parallelepiped shape of similar dimensions. As an example, the material(s) will be chosen with a Shore A hardness of, for example, at least 20 or even at least 30, and for example at most 90 or even at most 70.

[0020] According to yet another advantageous embodiment, the device according to the invention includes a temperature sensor, and the calculation module includes a memory which associates a first panel, of stiffnesses of said at least one elastically deformable element, with a second panel, of temperatures.

[0021] The invention also relates to a braking system comprising a device as defined above.

[0022] The system preferably includes a disc brake system, preferably with a floating caliper.

[0023] According to an alternative embodiment, the braking system is a hydraulic braking system.

[0024] The invention also relates to a method for controlling a brake system equipped with a device as defined above. The control method according to the invention is remarkable in that it comprises the following steps: - activation of said engine at a given moment, by control of said braking system (by a user), - measurement of a first angle of rotation of said input shaft in an actuated position, - measurement of a second angle of rotation of said output shaft in the actuated position, - estimation of a couple at a given instant from the first and second measured angles, the said reduction coefficient and the stiffness of at least one elastically deformable element, by the said calculation module, - transmission of said estimated torque, at said given instant, at said brake control system, and - control of the operation of said engine by said brake control system, taking into consideration, in said control law, said estimated torque at said given instant.

[0025] Advantageously, the calculation module uses the estimated torque value data within a closed-loop regulation implemented to adjust the applied braking force, in particular as a function of a received setpoint, during a sequence including a braking command.

[0026] According to an advantageous embodiment, where the device comprises at least one elastically deformable element having a temperature-dependent stiffness, said method further comprises the following steps: - determination of the temperature at that given instant, - identification of a stiffness of said at least one elastically deformable element which corresponds to the stiffness of said element at said determined temperature,

[0027] said torque estimation step at said given instant taking into consideration said stiffness identified for said determined temperature.

[0028] Advantageously, the method includes a step in which the duration of the implementation of said elastically deformable element in said device is monitored and, when said duration reaches a predetermined duration, said system is warned of the obsolescence of said elastically deformable element and a predetermined stiffness is applied to carry out the torque estimation step.

[0029] Preferably, when the method implements a device comprising at least two elastically deformable elements, each having a different stiffness among which a low stiffness and a high stiffness, greater than said low stiffness, said method comprising a step according to which the moment is determined at which the elastically deformable element of low stiffness begins to produce an error, and / or the moment at which it no longer produces an error in favour of the elastically deformable element of high stiffness, and said determined moment is taken into consideration to modulate the control law, in order to make said determined moment correspond to a moment ("touchpoint") where the force produced by the motor begins to produce a clamping or braking effect, and for example where the clamping force to be applied is the greatest.

[0030] Thanks to the device and method according to the invention, it should be noted that the torque is monitored in real time to act on the control law.

[0031] LIST OF FIGURES

[0032] Other features and advantages of the invention will become apparent from the detailed description of implementations and embodiments, which are by no means limiting, and from the accompanying drawings where:

[0033] [Fig. 1] is a schematic representation of a device for a braking system according to the invention,

[0034] [Fig.2] is a perspective view of a pinion of a gear of a device in accordance with the invention,

[0035] [Fig.3] is also a perspective view of a pinion of a device according to the invention, which is assembled with the pinion shown in [Fig.2],

[0036] [Fig.4] illustrates the pinion of [Fig.3], assembled to the pinion of [Fig.2], and

[0037] [Fig.5] illustrate curves of calculated torque readings, motor angle and error angles for two examples of devices according to the invention, one with a single elastically deformable element, and the other with two elastically deformable elements of different stiffness.

[0038] DESCRIPTION OF EMBODIMENT METHODS

[0039] The embodiments that will now be described are not limiting: in particular, variants of the invention may be made comprising only a selection of features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0040] Of course, the invention is not limited to the examples that will be described, and many modifications can be made to these examples without departing from the scope of the invention. Furthermore, the various features, forms, variants, and embodiments of the invention can be combined in various ways, provided that they are not incompatible or mutually exclusive.

[0041] The invention applies mainly to the braking of motor vehicles.

[0042] Fig. 1 schematically illustrates a device according to the invention, implemented in a braking system.

[0043] The braking system can be a disc brake system, preferably with a floating caliper, or a hydraulic brake system.

[0044] The device includes a geared motor system: it thus includes a motor 1, associated with a reducer mounted in a pre-assembled cartridge 70 and which includes different stages of gears meshed with each other.

[0045] In [Fig.1], within the framework of the illustrated example, the geared motor comprises two stages of gear pinions.

[0046] The geared motor has a reduction coefficient which a person skilled in the art can determine based on the gears used, the number of reduction stages, etc.

[0047] The geared motor includes an input shaft 2, which is driven in rotation by the motor 1 when a braking command is received by a brake system control unit (for example, when the driver presses the brake pedal, when the vehicle control system commands automatic emergency braking, etc.). The force that the motor 1 must exert or its rotational speed is determined by a control law.

[0048] A first toothed pinion 3 is fixed on the input shaft of the reducer: it is coaxial with the input shaft 2 and is rotationally fixed to this shaft.

[0049] The pinion 3 meshes a pinion 5, by meshing its peripheral teeth with those of the pinion 3 whose axis is parallel to that of the input shaft 2: in this example, the pinion 5 is of a different size than that of the pinion 3 and it is considered to constitute, with the pinion 3, a first stage of the reducing device.

[0050] A second reduction stage is observed, comprising a pinion 8 which meshes with a pinion 4. An output shaft 6 of the reduction device is mounted on the axis of the pinion 4. and is rotationally fixed to pinion 4.

[0051] Between the two stages, the pinion 5 drives the pinion 8 in rotation.

[0052] According to the invention, the reducing device comprises an elastically deformable element 7 positioned between the two pinions 5 and 8, so that it is elastically deformed when the upstream pinion 5 drives the downstream pinion 8 in rotation, and that it angularly resists this drive by means of its stiffness.

[0053] It is understood here that the rotation of the shaft 2 by the motor 1 drives the pinion 3 in rotation, which drives the pinion 5 in rotation, which elastically deforms the elastically deformable element 7, which drives the pinion 8 in rotation, which drives the pinion 4 in rotation, which finally drives the output shaft 6 in rotation.

[0054] The elastically deformable element 7 can be of different natures, and it can also have different shapes and be assembled, with the gears 5 and 8, in several ways, depending on the nature of the element 7, depending on its shape or that of the gears 5 and 8 facing each other, for example.

[0055] Several elastically deformable parts 7 can also be provided between the gears 5 and 8, in parallel or in series.

[0056] In concrete terms, the elastically deformable element 7 can be made in several parts and include, for example, an element 7A and an element 7B, as illustrated in [Fig.3].

[0057] This or these deformable elements are for example made of material that is elastically deformable in compression, for example of EPDM type rubber.

[0058] As soon as the downstream pinion 8 opposes a reaction torque when braking begins, the rotation of the downstream pinion 8 begins to lag angularly with respect to the pinion 5, due to the elastic deformation of the elastically deformable part or parts 7 between them.

[0059] According to the invention, the device includes a first sensor 10, which allows the angular rotation of the input shaft 2 to be measured (i.e. its angular position at time t relative to its starting position at time t-1) when the motor 1 commands its rotation.

[0060] The device also includes a second sensor 20, which allows the angular rotation of the output shaft 6 to be measured when the pinion 4 is driven in rotation.

[0061] The sensors 10 and 20 are preferably position sensors. For example, sensors of the same technology may be provided, preferably magnetoresistive sensors which give precise measurements, and in particular of the giant magnetoresistance type, or GMR for "Giant Magnetoresistance" in Anglo-Saxon vocabulary.

[0062] It should be understood, however, that the invention is not limited to the presence of sensors of the same type: the sensors could be of different types, without going out within the framework of the invention, provided that they are capable of transmitting data relating to the angle of rotation made by the input shaft 2 and the output shaft 6 of the motor-reducer group, or their difference.

[0063] The "rest position of the input shaft" will be the position in which the input shaft is located when the motor 1 is not rotating the input shaft 2, and the "driven position of the input shaft" will be the angular position taken by the input shaft under the action of the motor 1 which drives the input shaft in rotation.

[0064] Similarly, the position in which the output shaft is not driven in rotation will be called the "rest position of the output shaft", and the angular position taken by the output shaft 6 when it is driven in rotation by the pinion 4, after actuation of all the pinions of the reducing device as explained above, will be called the "actuated position of the output shaft".

[0065] The objective of this device according to the invention is to determine the output torque of the geared motor device, which will actuate the elements ensuring braking, the torque of the geared motor group being related to the force of the geared motor and the load that it can set in motion.

[0066] The first sensor 10 accurately detects the rotation angle 0M of the input shaft 2 in the actuated position.

[0067] The second sensor 20 accurately detects the rotation angle 06 of the output shaft in the actuated position.

[0068] Without elastic transmission in the reducing device, the angle O corresponds to the following equation:

[0069] 06 = 0M / R6M

[0070] where R6 Mest is the reduction coefficient of the reducing device.

[0071] In the case of elastic transmission, as is the case in the device according to the invention, the angle of rotation 06 corresponds to the following equation:

[0072] 06= 0M / R6 M- 07,

[0073] where 07 corresponds to the "error" introduced by the elastically deformable element 7 under stress.

[0074] And:

[0075] 07= T / K,

[0076] where K is the stiffness of the elastically deformable element,

[0077] and where T corresponds to the pair sought.

[0078] By integrating the previous equations, we can determine the desired torque using the following equation:

[0079] T = (0M / R6.M-06).K

[0080] The device includes a computing module 30, with which the two sensors 10 and 20 communicate, and which communicates with a control unit U of the system of brake, so that the torque T is taken into consideration to act on the control law of motor 2.

[0081] Fig. 2 illustrates an example of an embodiment of a pinion 8 carrying rigid protruding fingers 81 which protrude from an axial face 80 of the pinion 8, distributed equidistant from the center of the pinion and between each other.

[0082] The rigid protruding fingers 81 are of such shape and dimensions that they are suitable to be accommodated in housings 9 of the gable 5 made, for example, in accordance with the representation given therein in [Fig.3].

[0083] Figure 3 also shows that the pinion 5 comprises two types of elastically deformable elements 7A and 7B, having different stiffnesses and positioned in series: elastically deformable elements 7A with a first stiffness K1, and elastically deformable elements 7B with a second stiffness K2, the second stiffness K2 being greater than the stiffness KL

[0084] The elastically deformable elements 7A and 7B have, for example, the same shape and size, but are made of different materials to have different stiffnesses.

[0085] The same shape and dimensions of elastically deformable elements make it easy to replace one elastically deformable element with another, depending on the stiffness that one wishes to use for the implementation of the process according to the invention and which will now be described.

[0086] It is indeed advantageous, for the implementation of the invention, to be able to have two levels of compression of elastically deformable elements to also act on the control law of the brake system: this makes it possible in particular, as will be seen later, to modulate the moment when the greatest clamping force must be applied by the braking system.

[0087] Fig. 4 illustrates the assembly of the pinions 5 and 8, with the protruding fingers 80 being inserted into the housings 9 of the pinion 5.

[0088] The pinion 8 has external peripheral teeth 82 which mesh with those of the pinion 4 (teeth not shown, the pinion 4 being shown schematically in [Fig.1]) and the pinion 5 has peripheral teeth which mesh with those of the pinion 3 (not shown, the pinion 3 being shown schematically in [Fig.1]).

[0089] It should be noted that the elastically deformable element(s) may exhibit, intentionally or unintentionally, a variation in stiffness depending on the climatic conditions, and in particular depending on the temperature to which it is subjected.

[0090] The invention provides for taking into consideration this temperature variation, so as to allow a precise calculation of the torque T.

[0091] For example, if the temperature to which the device is subjected is rather low (below 5 °C for example), the stiffness of the elastically deformable element will be more important than if the temperature is around 20°C.

[0092] Also, for a known elastically deformable element, its stiffness can be known as a function of a range of temperatures.

[0093] The torque calculation module 30 T can include a memory 31, which is capable of associating a temperature with a stiffness of an elastically deformable element, and in particular that which corresponds to the elastically deformable element implemented, which will have been previously entered.

[0094] The memory 31 thus comprises a panel of stiffnesses K associated with a panel of temperatures.

[0095] To enable real-time temperature identification, the device includes a temperature sensor 32, which communicates with the calculation module 30 ([Fig.l]) to transmit the temperature in real time, so that the calculation module identifies the stiffness to be taken into consideration in the calculation of the torque T.

[0096] Thus, to determine the torque, according to the method according to the invention, the temperature is determined at the given instant when the braking system is implemented, a stiffness K of the elastically deformable element is identified which corresponds to the stiffness of said element at said determined temperature, then the calculation of the torque is carried out as indicated previously at the given instant, taking into consideration the stiffness identified for the determined temperature.

[0097] In an example of implementation, the motor produces a torque of at least 0.5 Nm and less than 5 Nm, and for example of the order of 1 Nm; and, for a reducing device having a reduction coefficient between 20 and 60, and for example between 30 and 50.

[0098] For a configuration of this type, said at least one elastic element is made of elastomer, for example of the EPDM type. By way of example, such an elastically deformable element may have the shape of an angular sector taken from a circular joint of rectangular cross-section, the external dimensions of which are for example at least 3 mm or even 4 mm and for example at most 10 mm or at most 7 mm; or a substantially parallelepiped shape of similar dimensions.

[0099] By way of example, the material(s) will be chosen with a Shore A hardness of, for example, at least 20 or even at least 30, and for example at most 90 or even at most 70.

[0100] The lower the stiffness of the elastically deformable element, the more accurate the torque calculation will be.

[0101] On the other hand, the longer the elastically deformable element takes to deform, the longer the system takes to calculate the torque and transmit the information to the brake control system U to act on the control law.

[0102] Furthermore, the more deformable the element, the greater the absorption at the motor level and therefore an error to correct.

[0103] Thus, the choice of a stiffness of elastically deformable element must be taken into consideration in relation to the reduction coefficient and the power of the motor, so that the device allows an effective torque calculation without prejudice to the reaction time of the brake system which will control the force to be applied by taking into consideration the torque transmitted in its control law.

[0104] The curve shown in [Fig. 5] illustrates the angle of rotation 07 (also called "error") introduced by the elastically deformable elements 7A and 7B as a function of time and the angle of rotation 0M of the input shaft of the geared motor group, in the actuated position and the torque T of the assembly which has been calculated, as a function of time, in such a double stiffness system.

[0105] It is noted that the couple T begins to produce effective effects once the elastically deformable element 7A of low stiffness has finished acting on the system, and the other elastically deformable element 7B of higher stiffness takes over from the first element 7A.

[0106] In other words, in the device, and after the motor has imposed a minimum rotation angle 0Mi on the input shaft, it is noted that the low stiffness elastic element 7A is compressed rapidly, which allows a large error angle to be obtained quickly (see in 07i and 072): the resulting torque T is relatively low (see between Tl and T2 on the curve).

[0107] Even when the elastically deformable element 7A has been completely compressed, the other elastically deformable element 7B, with greater stiffness, still exhibits elastic deformation and thus characterizes the effective braking effort, until the maximum effort desired for the produced device is reached (see torque curve T from T2 and error curve 07 from 072).

[0108] With such a device comprising two elastically deformable elements of different stiffnesses (one low and the other high), it is possible to detect several moments in the braking which correspond to several technical effects produced, which have consequences on the braking itself.

[0109] For example, we can determine the moment when the pads come to touch the disc (called "touchpoint" in Anglo-Saxon vocabulary) for a drum brake: this makes it possible to detect that we are not making unwanted braking, and this makes it possible to use this point as "zero point" to apply the force necessary for braking.

[0110] The second point can correspond to the determination of the effort to be made in the system to brake: concretely, when the pads touch the disc, the braking of the vehicle begins and, from that moment, we can calculate the necessary force if we manage to determine the torque to be applied precisely.

[0111] As the device according to the invention makes it possible to calculate precisely this torque, taking into consideration the angle measurements, knowing the stiffness and ratio of the geared motor, the device according to the invention can be used to further improve the control law, for example by modulating the moment when the greatest effort must be applied, from the determination of the point of contact of the pad with the disc ("touchpoint") for example by starting to exert the necessary force as early as possible (for example in case of emergency braking).

[0112] Furthermore, the method according to the invention may have other features designed to ensure that the torque calculation remains as accurate as possible depending on the system's operating time:

[0113] For example, it is provided that an implementation time of said elastically deformable element is monitored in said device: for example, the calculation module 30 could include a clock enabling the brake control system U (which can warn the vehicle user, via a visual or audible alarm) of obsolescence of said elastically deformable element (or elastically deformable elements), when a predetermined usage time is reached, and applying a predetermined stiffness to carry out the torque estimation step while waiting for the change of the elastically deformable element(s).

[0114] It is understood from the preceding description how the invention makes it possible to achieve its objectives for accurately calculating the torque of a geared motor device in order to act on the control law of a brake system, taking into consideration the effects of climatic conditions, and in particular of temperature, on the elements of the reducing device.

[0115] It should be understood that the invention is not limited to the embodiments presented above, and that it extends to the implementation of any equivalent means.

[0116] In particular, the elastically deformable element(s) can be mounted between a coaxial pinion and shaft, or between two coaxial shafts even if they do not carry a pinion.

[0117] For example, it should be understood that the stages of the reducing device could include further rotating drive elements or that the reducing device could include more than two stages, without departing from the scope of the invention.

[0118] Finally, the braking system device according to the invention can be mounted on one of the wheels of a vehicle, or on both drive wheels, or on all four wheels, without going out of the scope of application of the invention.

[0119] The invention is advantageously applicable to a brake operating in a fully electrical manner, including for service braking.

[0120] NOMENCLATURE

[0121] 1: motor

[0122] 2: input tree

[0123] 3: pinion

[0124] 4: pinion

[0125] 5: pinion

[0126] 6: output tree

[0127] 7: elastically deformable element

[0128] 7A: elastically deformable element with low stiffness Kl

[0129] 7B: elastically deformable element with high stiffness K2

[0130] 8: pinion

[0131] 9: housing for an elastically deformable element

[0132] 10: first angular position sensor

[0133] 20: second angular position sensor

[0134] 30: torque calculation module T

[0135] 31: Calculation module memory

[0136] 32: temperature sensor

[0137] 51: peripheral teeth of pinion 5

[0138] 70: reducer cartridge

[0139] 80: face of pinion 8

[0140] 81: protruding fingers of the face 80

[0141] 82: peripheral teeth of pinion 8

[0142] U: Brake control system

[0143] Kl: low stiffness

[0144] K2: high stiffness

[0145] 07: error introduced by the elastically deformable element(s)

[0146] 07i: error at the beginning of compression of element 7A

[0147] 072: Error at the end of compression of element 7A

[0148] 0M: angle of rotation of the input shaft imposed by the motor

[0149] 0M1: angle of rotation of the input shaft at the beginning of the compression of element 7A

[0150] 0M2: angle of rotation of the input shaft at the end of the compression of element 7A

[0151] T: couple

[0152] Tl: torque calculated at the beginning of the compression of element 7A

[0153] T2: torque calculated at the end of the compression of element 7A

Claims

Demands

1. A force-measuring device for a brake system comprising a motor (1) for rotating a gear reduction device (3, 4, 5, 8) having, for applying a braking force to at least one brake shoe, at least one gear train of one or more stages of gears having a reduction ratio ranging from one to two hundred and fifty, in particular of at least twenty and / or at most fifty, said system comprising an input shaft (2) arranged to be rotated by said motor (1) according to a control law and to drive an output shaft (6) via said gear train, said device for a brake system being characterized in that it comprises: - a first sensor (10), positioned upstream of said gear train so as to measure the angular rotation (0M) of said input shaft (2) between a rest position where the motor (1) does not rotate the input shaft (2) and an actuation position where the motor (1) rotates the input shaft (2), - a second sensor (20), positioned downstream of said gear train so as to measure the angular rotation (06) of said output shaft (6) between a rest position where the output shaft (6) is not driven in rotation and an actuation position where the reduction device drives the output shaft (6) in rotation, in that said reduction device comprises at least one elastically deformable element (7, 7A, 7B), positioned between said input shaft (2) and said output shaft (3) of the reduction device so as to be elastically deformed by a torque transmitted from the input shaft (2) to the output shaft (6), said elastically deformable element (7, 7A, 7B), having a stiffness (K1, K2), and in that it comprises a calculation module (30) for a torque (T) transmitted by the reduction device at a given instant, based on the angular rotation data (0M,06) transmitted at said given instant by the said first and second sensors (10, 20), of the said stiffness (Kl,K2) of the elastically deformable element (7, 7A, 7B) and of the reduction coefficient of said reducing device.

2. Device according to claim 1, characterized in that the element de- elastically deformable (7, 7A, 7B) is interposed between two coaxial parts (5, 8) of the reducer, one of which drives the other in rotation after compensation of an angular play between them, said angular compensation being obtained partially or exclusively by compression of said elastically deformable element between two bearing surfaces carried by said coaxial parts.

3. Device according to any one of the preceding claims, characterized in that the elastically deformable element (7, 7A, 7B) is interposed between two coaxial gears which belong to two different gear stages within the reducer, and one of which (5) drives the other (8) in rotation after compensating for an angular backlash producing a deformation of said elastically deformable element.

4. Device according to any one of the preceding claims, characterized in that the reducing device comprises one or more stages whose shafts are mounted in the same structure forming a transmission cartridge, and in that the elastically deformable element and / or the second sensor (20) is mounted on a shaft which is driven by said cartridge.

5. Device according to any one of the preceding claims, characterized in that the electric motor (1) is of a vector type integrating an angular position sensor which is used as a first sensor (10), in particular a brushless DC motor.

6. Brake system device according to any one of the preceding claims, characterized in that said first sensor (10) and said second sensor (20) are position sensors of the same technology, preferably magnetoresistive sensors in particular with giant magnetoresistance.

7. Brake system device according to any one of the preceding claims, characterized in that it comprises at least two elastically deformable elements (7A, 7B), said at least two elastically deformable elements (7A, 7B) having different stiffnesses (K1, K2).

8. Device according to claim 7 characterized in that said at least two deformable elements (7A, 7B) have the same shape and dimensions.

9. A device according to any one of the preceding claims, characterized in that it comprises a temperature sensor (32) and in that the computing module (30) comprises a memory (31) which associates a

10.

11.

12.

13. first set of stiffness values ​​(Kl, K2) of said at least one elastically deformable element (7, 7A, 7B) at a second set of temperatures. Brake system comprising a device according to any one of the preceding claims. A brake system according to claim 10, characterized in that it comprises a disc brake system, preferably with a floating caliper. A brake system according to claim 10, characterized in that it comprises a hydraulic brake system. Method of controlling a brake system equipped with a device according to any one of claims 1 to 9, comprising a motor (1) for rotating a gear reduction device (3, 4, 5, 8) having, for applying a braking force to at least one brake shoe, at least one gear train of one or more stages of gears having a reduction ratio ranging from one to two hundred and fifty, in particular of at least 20 and / or at most 50, said system comprising: • an input shaft (2) arranged to be driven in rotation by said motor (1) according to a control law and to drive an output shaft (6) via said gear train, • a first sensor (10), positioned upstream of said gear train so as to measure the angular rotation (0M) of said input shaft (2) between a rest position where the motor (1) does not rotate the input shaft (2) and an driven position where the motor (2) rotates the input shaft (2), and • a second sensor (20), positioned downstream of said gear train so as to measure the angular rotation (06) of said output shaft (6) between a rest position where the output shaft (6) is not driven in rotation and an actuation position where the reduction device drives the output shaft (6) in rotation, said reducing device comprising at least one elastically deformable element (7, 7A, 7B), positioned between said input shaft (2) and said output shaft (3) of the reducing device so as to be deformed elastically by a torque transmitted from the input shaft (2) to the output shaft (6), said elastically deformable element (7, 7A, 7B), having a stiffness (Kl, K2), and a calculation module (30) of a torque (T) transmitted by the reducing device at a given instant, from the angular rotation data (0M,06) transmitted at said given instant by said first and second sensors (10, 20), of said stiffness (Kl, K2) of the elastically deformable element (7, 7A, 7B) and of the reduction coefficient of said reducing device, said control method being characterized in that it comprises the following steps: - actuation of said engine (1) at a given moment, by control of said braking system, - measurement of a first angle of rotation (0M) of said input shaft (2) in the actuated position, - measurement of a second angle of rotation (06) of said output shaft (6) in the actuated position, - estimation of a couple (T) at said given instant from the first and second measured angles (0M>06), of said reduction coefficient and of the stiffness (Kl, K2) of said at least one elastic element (7, 7A, 7B), by said calculation module (30), - transmission of said estimated torque (T) at said given instant, to said brake control system (U), and - control of the operation of said motor (2) by said brake control system, taking into consideration, in said control law, said torque (T) estimated at said given instant.

14. Method according to claim 13, characterized in that the calculation module (30) uses the estimated torque value (T) data within a closed loop regulation implemented to adjust the braking force applied during a sequence including a braking command.

15. A method according to claim 13 or 14 wherein said at least one elastically deformable element (7, 7A, 7B) has a stiffness (K1, K2) which depends on the temperature, said method further comprising the following steps: - determination of the temperature at that given instant, - identification of a stiffness (Kl, K2) of said at least one elastically deformable element (7, 7A, 7B) which corresponds to the stiffness of said elastically deformable element at said determined temperature, and in that said torque estimation step (T) at said given instant takes into consideration said stiffness identified for said determined temperature.

16. A control method according to any one of claims 13 to 15, characterized in that a duration of implementation of said elastically deformable element (7, 7A, 7B) in said device is monitored and in that, when said duration reaches a predetermined duration, said brake system is warned of obsolescence or degradation of said elastically deformable element (7, 7A, 7B) and a predetermined stiffness is applied to carry out the torque estimation step.

17. A control method according to any one of claims 13 to 15, implementing a device comprising at least two elastically deformable elements (7A, 7B), each having a different stiffness (Kl, K2) including a low stiffness (Kl) and a high stiffness (K2), greater than said low stiffness (Kl), said method comprising a step in which the moment at which the elastically deformable element (7A) of low stiffness (Kl) begins to produce an error is determined, and / or the moment at which it no longer produces an error in favour of the elastically deformable element (7B) of high stiffness (K2), and in that said determined moment is taken into consideration to modulate the control law, in order to make said determined moment correspond to a moment when the force produced by the motor begins to produce a clamping or braking effect, and for example where the clamping force to be applied is the greatest.