WO2023175458A1

WO2023175458A1 - Motor vehicle with tilting block device and related method

Info

Publication number: WO2023175458A1
Application number: PCT/IB2023/052300
Authority: WO
Inventors: Mario SANTUCCI; Stivi PERON; Onorino Di Tanna
Original assignee: Piaggio & C. S.P.A.
Priority date: 2022-03-14
Filing date: 2023-03-10
Publication date: 2023-09-21
Also published as: IT202200004796A1; EP4493421A1; IL315622A; JP2025509692A

Abstract

In a tilting saddle-riding motor vehicle with a tilting block system, a control unit is provided, activating a pre-approaching movement of the tilting block caliper towards an incipient block position, before activating the complete block of the tilting movement. The incipient block position can be calibrated. The tilting block is therefore quicker.

Description

TRANSLATION (RULE 12.3) 07 APR. 23

1

MOTOR VEHICLE WITH TILTING BLOCK DEVICE AND RELATED METHOD

DESCRIPTION

TECHNICAL FIELD

[0001] The present invention relates to the sector of so-called tilting motor vehicles, i.e. motor vehicles provided with a tilting movement around a median plane that extends longitudinally along the vehicle. Embodiments disclosed herein relate to tilting, i.e. rolling, saddle-riding vehicles, with at least a rear drive wheel and two front steered wheels.

BACKGROUND ART

[0002] In the field of motor vehicles, vehicles are increasingly offered that combine the ease of handling of the saddle-riding vehicles with two wheels (e.g. motorcycles and scooters) with the stability of the vehicles with four-wheels. Among these vehicles there are three-wheeled motor vehicles provided with two front steered wheels and a rear drive wheel, and four-wheeled motor vehicles, typically called quad bikes.

[0003] In more detail, the above-mentioned three-wheeled motor vehicles are provided with two front wheels that are steered, i.e. adapted to steer the vehicle controlled by the driver through the handlebars, and tilting, i.e. adapted to laterally tilt with a tilting movement. The tilting movement is an oscillation movement about an axis directed essentially in the direction of travel. The three-wheeled vehicles also include a rear drive wheel that is mechanically coupled to the engine and has the purpose of providing the driving torque, and therefore of allowing traction, whilst the paired front wheels provide the vehicle directionality.

[0004] In addition to the steering movement, the paired front wheels have a tilting movement and are connected to the vehicle frame through suspensions, which allow a springing movement. Through the use of two paired front wheels, a tilting vehicle has greater stability compared to a motor vehicle with only two wheels, thanks to the double support of the front wheels on the ground, similar to the support provided by a car. [0005] The front wheels are coupled to each other by kinematic mechanisms ensuring them tilt and steer substantially synchronously, for example by the interposition of one or two four-bar linkages connecting the front wheels to a front end. These motor vehicles are often provided also with two independent suspensions, one for each front steered wheel. Each suspension is equipped with an elastic element (spring) and a viscous element (shock absorber).

[0006] Even if highly stable, under certain conditions the three- and four-wheeled tilting motor vehicles are likely to fall due to an uncontrolled tilting movement. This can especially occur when the motor vehicle moves at low speed, is stationary or parked. To avoid this inconvenience, the tilting motor vehicles with three or four wheels are usually equipped with a tilting block device, or tilting control device, which prevents the motor vehicle from accidentally falling when it is stationary or moves at low speed. Three-wheeled motor vehicles with tilting block or tilting control devices are disclosed for example in WO2017115293; WO2017115294; WO2017115295; WO20171 15296; WO2017115297; WO2018116210;

WO2018116211; US7264251 and EP1561612.

[0007] It has been found that the tilting block devices are very helpful in increasing driving safety and comfort. However, they can still be improved in some respects.

[0008] Typically, the tilting block is manually activated by the driver when the motor vehicle is stopping or has stopped. In some cases, automatic tilting block systems have also been developed, which intervene when the speed of the motor vehicle is lower than a threshold value close to zero.

[0009] One of the problems of the tilting block devices is that they operate rather slowly. In other words, from the moment when the tilting block is (manually or automatically) activated to the moment when the tilting movement is actually blocked, a few tenths of second pass, due to the stroke that the block caliper must perform. The caliper stroke can increase over time due to the wear of the brake pads. The driver therefore risks to lose balance, because the motor vehicle completely stops before the tilting motion is effectively stopped. However, it is not possible to anticipate the activation of the tilting block excessively, for example to block the tilting movement in an instant when the motor vehicle still moves at a significant speed, because this entails serious risks of falling. In fact, blocking the tilting movement when the motor vehicle is still moving can cause the motor vehicle to overturn, for example if one of the front wheels encounters an uneven ground.

[0010] It would be therefore useful to provide a tilting block device which overcomes the drawbacks of the prior art devices. Particularly, it would be useful to provide a tilting block device which requires a shorter intervention time, i.e. which is quicker in blocking the tilting movement of the motor vehicle.

SUMMARY

[0011] According to an aspect, a tilting saddle-riding motor vehicle is provided, comprising two front steered wheels and at least one tilting four-bar linkage connecting the front steered wheels to a frame. The motor vehicle also comprises a block member integral with a component of the tilting four-bar linkage and a caliper co-acting with the block member and adapted to block the tilting four-bar linkage relative to the frame. The caliper is controlled by an actuator, for example, but not exclusively, an electric motor, if necessary equipped with a gear box. A control unit is also provided, functionally connected to the caliper control actuator. The control unit is adapted to control a pre-approaching movement of the caliper towards the block member based on a motor vehicle ride parameter, the pre-approaching movement bringing the caliper from a completely open position to a position of incipient block of the tilting movement relative to the block member.

[0012] In this way, when the ride parameter indicates that a tilting block may be soon necessary, for example before stopping at a traffic light, the caliper of the tilting block system is brought to a position close to the block position, so that the tilting block can be actuated in a shorter time.

[0013] Advantageously, the ride parameter of the motor vehicle is a driving speed of the motor vehicle and the control unit is adapted to control the pre-approaching movement when the driving speed is lower than a minimum threshold value.

[0014] As described in detail below with reference to the accompanying drawings, in advantageous embodiments, the control unit is adapted to perform a step of calibration of the incipient block position. The calibration step can be performed upon request by the user or automatically, for example every time the caliper is controlled to move to a tilting block position, or only in conjunction with some of the tilting block controls.

[0015] The complete block of the tilting can be controlled automatically based on a ride parameter, typically for example the driving speed. In other embodiments, currently preferred for safety reasons, the tilting block is controlled manually. In both cases, thanks to the approaching movement of the caliper towards the block member in a pre-blocking step, in which the jaws are positioned in the incipient block position, the advantage is obtained of an effective block of the tilting movement which is faster than in the prior art systems.

[0016] Further advantageous features and embodiments of the motor vehicle are described below and defined in the attached claims.

[0017] The invention also concerns a method for managing the tilting block in a tilting saddle-riding vehicle of the type defined above. Features of various embodiments of the method are described below and defined in the attached claims.

BRIEF DESCRIPTION OF THE DRAWING

[0018] The invention will be better understood by following the description below and the attached drawings, showing a non-limiting embodiment of the invention. More specifically, in the drawings:

Fig.1 is an axonometric view of a motor vehicle, with some parts removed;

Fig.2 is a front view of the front axle of the motor vehicle, with the front steered wheels, the suspensions and the tilting four-bar linkage, where the rear wheel and other components of the motor vehicle have been omitted for greater clarity of representation;

Fig.3 is an axonometric view of the tilting block device;

Figs.4, 5 and 6 show diagrams with different positions of the tilting block caliper; Fig.7 shows a block diagram of a method according to the present description;

Figs.8 and 9 show diagrams of various operating quantities of the motor vehicle and the tilting block system; and

Figs.10 and 11 are two flowcharts summarizing further methods according to the present invention, with calibration of the incipient block position.

DETAILED DESCRIPTION

[0019] In the following description and in the attached drawings, reference will be made to a tilting saddle-riding motor vehicle with a rear drive wheel and two front steered wheels, with a single tilting four-bar linkage connecting the two front steered wheels to the frame of the motor vehicle. However, it must be understood that many novel aspects disclosed herein can be advantageously applied also to other types of tilting saddle-riding vehicles, for example motor vehicles with four wheels. Additionally, the novel features of the tilting block control system can also be implemented on systems with a double tilting four-bar linkage.

[0020] With reference to the drawings, Fig.1 shows an axonometric view of a motor vehicle 1 according to an embodiment. In Fig.l and in the other figures, the arrow U indicates the upward direction, the arrow D indicates the downward direction, the arrows L and R indicate the left and right direction respectively. F and B indicate the forward direction (driving direction) and the backward direction respectively.

[0021] The motor vehicle 1 comprises a frame 3, to which a rear drive wheel 5 is connected. The rear drive wheel is coupled to an engine, not shown. Reference number 9 indicates the saddle of the motor vehicle 1. In Fig.l, the panels of the body of the motor vehicle have been omitted, as well as the engine and the transmission members thereof, and anything else not necessary for understanding the present invention.

[0022] In other embodiments, not shown, the motor vehicle 1 comprises two rear drive wheels instead of only one rear drive wheel.

[0023] With reference to the attached drawings, the motor vehicle 1 comprises, at the front, a front end 11 including a steering, a pair of front steered wheels and a mechanism connecting the front steered wheels, and the suspensions thereof, to the frame 3, so as to allow the motor vehicle to perform tilting movements, i.e. pivoting movements around a horizontal axis parallel to the direction of travel and lying on the ground, i.e. on the support surface of the motor vehicle. [0024] More specifically, the front axle 11 comprises a steering column 13, to which a handlebar 15 is connected, schematically indicated by a dotted line. The steering column 13 is rotatably housed in a steering sleeve 14 integral with the frame 3 or forming part of it. The driver, through the steering column 13, transfers a steering movement to the two front steered wheels, more precisely the left front steered wheel 17A and the right front steered wheel 17B. The steering movement is transferred to the front steered wheels 17A, 17B through a steering rod 16.

[0025] One shock absorbing device is associated with each front steered wheel 17A, 17B, the device typically comprising an elastic component and a viscous component. More precisely, the reference number 19A indicates a left shock absorbing device associated with the left front steered wheel 17A, the reference number 19B indicates a right shock absorbing device associated with the right front steered wheel 17B.

[0026] The front steered wheels 17A, 17B, and the related shock absorbing devices 19 A, 19B, are connected to the frame 3 in such a way as to allow rotational (steering) movements of the front steered wheels 17A, 17B about respective steering axes indicated with Xa for the left front steered wheel 17A and with Xb for the right front steered wheel 17B. Furthermore, the front steered wheels 17 A, 17B are connected to the frame 3 in such a way as to allow the motor vehicle 1 to perform tilting movements, i.e. inclination movements around a horizontal axis passing through the support surface of the motor vehicle (indicated with S in Fig.2) for example when the motorcycle drives along a turn. The tilting movement is schematically represented by the double arrow R in Fig.2.

[0027] To allow these movements, the front end 11 of the motor vehicle 1 comprises a tilting four-bar linkage 21, which constitutes a mechanical connection between the front steered wheels 17A, 17B and the frame 3.

[0028] The tilting four-bar linkage 21, hereinafter briefly referred to simply as "four-bar linkage" 21, comprises an upper crossbar 23 and a lower crossbar 25, connected to the frame 3 as described below. The four-bar linkage 21 also comprises a left upright 27A and a right upright 27B, which constitute the rockers of the four- bar linkage 21 and are hinged to the upper crossbar 23 and to the lower crossbar 25. In the illustrated embodiment, the left front steered wheel 17A and the left shock absorbing device 19A are connected to the four-bar linkage 21 through a left arm 20A, rotatably housed inside the left upright 27A, so as to rotate about the left steering axis Xa. Similarly, the right front steered wheel 17B and the right shock absorbing device 19B are connected to the four-bar linkage 21 through a right arm 20B, rotatably housed inside the right upright 27B, so as to rotate about the right steering axis Xb.

[0029] The upper crossbar 23 is hinged, at an intermediate point of the longitudinal extension thereof, to a central element of the frame 3 or to an element rigidly connected to the frame 3, for example to the steering sleeve 14, or to an element integral therewith. The reference number 29 indicates the intermediate hinge point of the upper crossbar 23. In practice, the hinge point 29 defines a central hinge axis, about which the upper crossbar 23 rotates relative to the frame 3. The central hinge axis lies in a vertical median plane of the vehicle, the trace of which coincides with the axis A-A of Fig.2. The hinge axis extends in the direction of the median plane and is inclined downward in the direction of the arrow B, opposite to the forward direction (arrow F).

[0030] The lower crossbar 25 is hinged, at an intermediate point 36 of its longitudinal extension, to the central element of the frame 3. In practice, the hinge point 36 defines a central hinge axis, about which the lower crossbar 25 rotates relative to the frame 3. The central hinge axis lies in the vertical median plane of the vehicle, as does the hinge axis of the upper crossbar 23 hinged to the frame 3. The central hinge axis of the lower crossbar 25 extends, similarly to the central hinge axis of the upper crossbar 23, in the direction of the median plane and is inclined downward in the backward direction (arrow B).

[0031] Under certain conditions of the motor vehicle 1, it is convenient to prevent the upper crossbar 23 and the lower crossbar 25 from tilting i.e. rotating relative to the frame 3. This is the case for example when the motor vehicle 1 is stationary or almost stationary, typically when stopping at a traffic light. By blocking the tilting movement (arrows R, Fig.2) when the motor vehicle is in vertical position (i.e. with tilting angle equal to zero) the driver can keep his/her balance remaining sit on the saddle of the motor vehicle 1 without resting his/her feet on the ground, or placing his/her feet on the ground but without having to support the weight of the motor vehicle 1. Conversely, when the motor vehicle 1 is moving, even at moderate speed, the tilting movement must be free.

[0032] The motor vehicle 1 is therefore provided with a tilting block device, indicated as a whole with the number 51 and shown in Fig.3, but partially removed in Figs. 1 and 2 for greater clarity of representation. The tilting block device 51 comprises a block member 53, integral with one of the elements or components of the four-bar linkage 21, i.e. with one of the crossbars 23, 25 or the uprights 27A, 27B. In the illustrated example, the block member 53 is integral with the lower crossbar 25, i.e. rigidly connected thereto, as shown in particular in Fig. 2.

[0033] The block device 51 also comprises a caliper, indicated as a whole with the number 55, and an actuator 57 controlling the opening and closing of the caliper. In the illustrated embodiment, the actuator 57 comprises an electric motor with a reduction gear, indicated as a whole with reference number 59. The actuator 57 has been omitted in Figs. 1 and 2 for the ease of representation, and is shown only in the axonometric view of Fig. 3.

[0034] In the illustrated embodiment, the opening and closing movement of the caliper 55 is controlled through a cable 63 inserted in a sheath 61. One end of the cable 63 is anchored to a control element of the caliper 55, while the other end of the cable 63 is fixed to an element 65, movable with a rotational movement f65 around an actuation axis, controlled by the motor 59.

[0035] By rotating the element 65 in the direction causing traction of the cable 63, the caliper 55 is closed, thus clamping the block member 53 between two jaws 55A, 55B, schematically shown also in Figs. 4, 5 and 6. The caliper can be opened by means of an elastic member (for example a compression spring) when the cable 63 is released.

[0036] Figs. 4, 5 and 6 show the closing movement of the caliper 55. In Fig.4 the caliper 55 is completely open and does not interfere with the block member 53. In Fig. 6, the caliper 55 is closed, and grips the block member 53 between the two jaws 55A, 55B. Since the caliper 55 is integral with the frame 3 of the motor vehicle 1, when the caliper grips the block member 53, the entire four-bar linkage 21 is made integral with the frame 3 and cannot be deformed. The tilting movement of the motor vehicle 1 is prevented, i.e. blocked.

[0037] Fig. 5 shows an intermediate position of the caliper 55, where the jaws 55A, 55B have completed a part of the closing stroke, but are not yet gripping the block member. This position is called herein “incipient block position”, as it is a position which precedes the block position of the four-bar linkage 21 (Fig.6). The incipient block position has a unique function in the context of the operation of the tilting block device 51, which will be explained later. Preferably, in the incipient block position there is no mutual contact between the jaws 55A, 55B and the block member 53. In further, currently less preferred embodiments, in the incipient block position of Fig.5, the jaws 55A 55B (or one of them) may be in contact with the block member 53, without however exerting a force sufficient to block the tilting movement.

[0038] The actuator 57 is associated with a position sensor, for example a potentiometer or an encoder, which is configured to detect the position of the actuator, or of an element thereof, mechanically connected to the jaws 55 A, 55B of the caliper 55. Fig.3 shows two points where the position sensor 70 can be provided. The position sensor 70 can be mounted, for example, on the shaft of the motor 59 (position 70a in Fig.3), and detect the position of the actuator by counting the angle of rotation of the shaft of the motor 59. In other embodiments, the position sensor is aligned with the movable element 65 (position 70b in Fig.3) and detects the angular movement of the movable element 65, which corresponds to the movement of the cable actuating the caliper 55. In further embodiments, not shown, the position sensor is mounted on a screw mechanism, which transfers the motion from the cable 61 to the jaws 55A, 55B.

[0039] The actuator 57 is connected to a control unit, schematically indicated with number 71 in Fig.3. The central control unit 71 can be a dedicated control unit, or a central control unit of the motor vehicle 1. For the purposes of the present disclosure, in addition to be functionally connected to the actuator 57, the control unit 71 is also functionally connected to the position sensor 70 of the caliper 55 and to a sensor detecting at least one ride parameter of the motor vehicle 1. In the embodiment described herein, the ride parameter is the driving speed of the motor vehicle 1 and the sensor can comprise a tachometer, schematically indicated with the reference number 73, adapted to detect the speed of the motor vehicle 1.

[0040] The control unit 71 is also functionally connected to an interaction sensor, schematically indicated with 75, for detecting the interaction between the caliper 55 and the block member 53. In the present context, the term “caliper-block member interaction sensor” refers to any instrument, control unit, sensor, group of sensors, or group of instruments, capable of detecting one or more quantities which provide information on the physical interaction between the caliper 55, i.e. the jaws 55A, 55B, and the block member 53.

[0041] In the embodiment disclosed herein, the interaction sensor 75 comprises devices adapted to detect, directly or indirectly, the current absorbed by the electric motor 59 of the actuator 57. As it will be described in greater detail below, the current absorbed by the electric motor 59 varies based on the interaction between the jaws 55A, 55B of the caliper 55 and the block member 53; more precisely, the absorbed current increases as the force exchanged between the caliper 55 and the block member 53 increases.

[0042] The tilting block device 51 operates as follows.

[0043] While the motor vehicle drives, the caliper 55 of the tilting block device 51 is in the completely open position of Fig. 4.

[0044] When the motor vehicle 1 slows down and the driving speed, detected by the tachometer 73 or other suitable sensor, drops below a threshold value Vmin, the control unit 71 activates the tilting block device 51 so as to cause a partial closure of the caliper 55, with a pre-approaching movement of the jaws 55A, 55B of the caliper 55. This pre-approaching movement brings the jaws 55A, 55B from the completely open position (Fig.4) to the incipient block position of Fig.5. In this position, the active surfaces 551 A, 55 IB of the jaws 55A, 55B of the caliper 55 are preferably at a minimum distance from the opposite surfaces 531 A, 53 IB of the block member 53. In this condition, the mutual position of the jaws 55A, 55B and the block member 53 is still such as not to block the tilting movement, i.e. the jaws are not in contact with the block member 53, or at most they touch it without exerting a sufficient blocking force. [0045] The incipient block position is achieved by actuating the electric motor 59 of the actuator 57 through the control unit 71 and controlling the pre-approach stroke of the jaws 55A, 55B up to the incipient block position of Fig.5. The position sensor 70 detects the position of the caliper 55, i.e. of the jaws 55A, 55B thereof, and transmits the information to the control unit 71. The control unit stops the preapproaching movement when the incipient block position has been reached.

[0046] The incipient block position can be a stored piece of information available to the control unit 71.

[0047] As will be described in greater detail below, in preferred embodiments of the invention, the incipient block position can vary over time in order to take into account the change in the clearances due to wear and in particular to the wear of the brake pads of the jaws 55 A, 55B.

[0048] In practical embodiments, the incipient block position can be calibrated every time the tilting block device 51 is actuated, or only sometimes, randomly or every N actuations of the tilting block device 51, where N>1. A calibration cycle will be described below.

[0049] Once the tilting block device 51 has achieved the incipient block position of Fig.5, various situations can arise. If the motor vehicle speeds up, the control unit 71 activates the actuator 57 to bring the caliper 55 back to the completely open position (Fig.4). If the motor vehicle 1 continues to slow down and finally stops, the tilting block device can be actuated by completing closing the caliper 55 (Fig.6). The tilting block can be controlled automatically, for example when the driving speed of the motor vehicle is close to zero. Preferably, the tilting block is controlled by the driver, for example through a control button provided on the handlebar.

[0050] The tilting movement can be blocked more efficiently through the device disclosed herein, as the caliper 55 has previously been moved (automatically and without the need for the driver’s intervention) to the incipient block position of Fig.5. The subsequent activation of the tilting block, when the speed of the motor vehicle 1 further decreases, eventually to zero, is significantly faster, as the closing stroke of the jaws 55A, 55B is substantially shorter than what is necessary in the prior art systems. In fact, a large part of the closing stroke of the caliper 55 has already been carried out beforehand, when the speed of the motor vehicle has dropped below the threshold Vmin but is still higher than the speed at which the tilting movement can be completely stopped.

[0051] In some embodiments, this corresponds to a 20-70% reduction in the time necessary for closing the caliper 55 in the tilting block position of Fig. 6 compared to the time required by prior art devices. The greater readiness of the tilting block system results in greater comfort and greater safety. In particular, it allows to activate the tilting block at very low speeds, practically null speeds, reducing the risk of an accidental loss of balance caused for example by a too slow activation of the tilting block, i.e. by a too long time interval (even in the order of one second) between the instant of activation of the tilting block and the instant in which the tilting movement is actually blocked.

[0052] The problem is substantially alleviated or solved thanks to the greater timeliness of activation of the tilting block obtained by the pre-approaching stroke of the caliper 55 toward the incipient block position.

[0053] The flowchart of Fig.7 summarizes the method described above. In the diagram, Vo indicates the speed below which the tilting movement is blocked.

[0054] The pre-approaching stroke toward the incipient block position (Fig.5) can be optimized by taking into account the clearances between the mechanical members of the block device 51.

[0055] In fact, especially the pads 552A, 552B of the jaws 55A, 55B are subjected to wear and can reduce in thickness. The caliper 55 is controlled to the incipient block position based on a signal from the position sensor 70. The sensor detects the position of a mechanical element kinematically constrained to the caliper. To a given position of the position sensor 70 can correspond variable positions of the active surfaces 551 A, 55 IB of the jaws 55A, 55B, and therefore variable distances between the active surfaces 551 A, 55 IB of the jaws and the opposite active surfaces 531 A, 53 IB of the block member 53. This variation may be due to the wear and/or variation of the clearances of the various members which transmit the motion from the motor 59 to the caliper, or of other members of the tilting block device 51. In some cases, variations may also occur as a consequence of disassembly and reassembly operations, for maintenance, cleaning or repair reasons, or also as a result of the accumulation of debris on the members of the tilting block system.

[0056] These variations can lead to a reduction in the efficiency of the system described herein, as due to the wear the incipient block position (Fig.5) is no longer optimal and the distance between jaws 55A, 55B and block member 53 can become greater than that strictly necessary for right and safe operation of the mechanism described herein. It is even possible that, due to accidental events, in the incipient block position detected by the position sensor 70, the jaws 55A, 55B have come too close to the block member 53, interacting with it with a more or less high contact force, which hinders, to a certain extent, the free tilting movement of the motor vehicle 1, whereas the tilting movement must preferably remain completely free until the block is activated.

[0057] To overcome this drawback partially or completely, in improved embodiments of the device described herein, a step of calibration of the incipient block position can be provided. This calibration step can be performed for example when the engine of the motor vehicle 1 is started, for example manually controlled by the user, before starting driving.

[0058] However, the calibration step can preferably be performed every time the tilting block device 51 is activated, or randomly in conjunction with some of the activation steps of the tilting block device 51, or every N activations of the tilting block device 51. In general, it is advantageous for the calibration step to be started and performed automatically by the control unit 71, for example.

[0059] The calibration step can be performed by using an interaction sensor for detecting the interaction between the caliper 55 and the block member 53. The interaction sensor can be a sensor giving a direct interaction signal, or a sensor giving an indirect signal of the interaction between the caliper 55 and the block member 53.

[0060] In the embodiment described herein, the caliper-block member interaction sensor is a device that detects a quantity correlated to the current absorbed by the electric motor 59 of the actuator 57. This solution is particularly advantageous, because it does not require more components than those with which the electric motor 59 is usually provided. A current sensor detects the current absorbed and generates a signal for the control unit 71. The control unit can process the current signal, for example by extracting therefrom a function over time of the current. In embodiments described herein, the control unit 71 calculates the time derivative of the current absorbed by the electric motor 59.

[0061] In other embodiments, the caliper-block member interaction sensor is a force sensor, for example a load cell, which detects the force exchanged between the block member 53 and the caliper 55, for example one or both jaws 55A, 55B. The load cell is fixed to the block member 53, for instance. In other embodiments, a distance sensor is provided, which measures the distance between one or both active surfaces 531 A, 53 IB and the respective active surface 552A, 552B of the jaw 55A, 55B. The distance sensor can be a capacitive sensor, an optical sensor, or a sensor of other kind.

[0062] With reference to the drawings again, Fig.8 shows a diagram illustrating the current Cl absorbed by the electric motor 59 as a function of time when the tilting block is activated. The curve C2 is a position signal of the position sensor 70 associated with the caliper 55. The current Cl has a pattern which shows a peak in the instant when the electric motor 59 is activated, corresponding to the starting torque. Then, the current is approximately constant until the jaws 55A, 55B touch the surfaces of the block member 53. At this point, the mechanical resistance, which is encountered by the jaws in their advancement motion until the caliper 55 is completely closed, causes an increase in the absorbed current. The instant tl indicates the moment when the mechanical interaction between the caliper 55 and the block member 53 begins. The curve C2 has an approximately linear pattern from the beginning of the closing stroke (instant tO) up to the instant t2, where the closing movement of the caliper 55 ends.

[0063] The diagram of Fig.8 represents a situation where the tilting block occurs in a single operation, i.e. with a gradual closing movement from the position of Fig. 4 to the position of Fig.6, and does not show the situation in which the caliper 55 remains in an incipient block position (Fig.5). In fact, Fig. 8 does not serve to represent the effective execution of a tilting block cycle, but to illustrate the change of the parameters involved and the way in which they can be used to carry out a calibration step of the incipient block position. [0064] From the diagram of Fig.8 it is clearly apparent that about half of the time required from the activation of the tilting block device 51 to the stop of the caliper is necessary to start the interaction between the caliper 55 and the block member 53.

[0065] The method and the device described herein essentially operate in such a way that the incipient block position Cx indicated on the curve C2 is reached in a pre-approaching step, when the driving speed V of the motor vehicle 1 falls below a value Vmin. In this way, the time interval [tl-tO] necessary to achieve the incipient block position elapses before the effective (automatic or manual) activation of the tilting block. When the driver, or an automatic activation system, activates the tilting block, the time required to achieve the effective block is [t2-tl ], less than [t2-t0],

[0066] In practice, to avoid excessive wear of the pads 552 A, 552B of the jaws 55A, 55B and/or to leave the movement of the tilting four-bar linkage 21 completely free up to the moment when the block is actually activated, the incipient block position Cx can be slightly different from the position where the mechanical contact between the jaws 55A, 55B and the block member 53 begins.

[0067] For the reasons mentioned above, if the incipient block position (Fig.5) were defined in a fixed manner as a value on curve C2, following the wear of the mechanical parts forming the tilting block device 51, and especially of the pads of the caliper, the incipient block position, i.e. the end of the pre-approaching stroke, would increase over time.

[0068] To avoid this, since a signal is available to the control unit 71 indicative of the effective interaction between the caliper 55 and the block member 53, it is possible to calibrate the point Cx every time the tilting block device 51 is activated, or only sometimes when the tilting block device 51 is activated.

[0069] In fact, at each tilting blocking cycle the current absorption curve Cl, or a function of this curve, can be detected and the control unit 71 can determine the actual position (from the curve C2) of the caliper 55 when the interaction between the caliper 55 and the block member 53 starts. This position can be stored as incipient block position. More precisely, and more suitably, the incipient block position is set equal to the position Cx corresponding to the start signal of the interaction between the caliper 55 and the block member 53, corrected by such a factor as to guarantee that in the incipient block position the jaws 55 A, 55B are not yet in contact with the block member 53. If Cx is the position read by the position sensor 70 which corresponds to the start of the mutual contact between the caliper 55 and the block member 53, the incipient block position can be set equal to [Cx -A] where A is a value chosen in a suitable way to keep, for example, a distance of a few tenths of a millimeter between the jaws 55A, 55B and the block member 53.

[0070] The diagram of Fig.8 shows that the current signal Cl is characterized by a certain ripple which makes it not particularly practical for carrying out the control described above. For this reason, in currently preferred embodiments, the control unit 71 can calculate, from the current signal Cl, the value of the time derivative of the current and, instead of the current signal, the derivative function can be used for calibrating the incipient block position. Fig.9 shows the derivative of the current (curve C3) and the position signal of the position sensor 70 (curve C2) as a function of time. C4 indicates a threshold value of the current derivative, which corresponds to the start of the contact between the caliper 55 and the block member 53. On the curve C2 the point Cx, corresponding to the start of the mutual contact between the caliper 55 and the block member 53, and the point [ Cx -A], assumed as the incipient block position, are indicated.

[0071] The step of calibrating the incipient block position therefore allows to determine this position when a tilting blocking operation is performed so that, when the driving speed V of the motor vehicle 1 drops below the threshold value Vmin, the tilting block device 51 always brings the caliper 55 to an incipient block position which guarantees the minimum distance between the active surfaces 551 A, 55 IB of the jaws of the caliper 55 and the block member 53, consistent with the correct operation of the tilting block device 51. This allows to always minimize the time [t2- tl] required for effective blocking the tilting four-bar linkage 21 when required.

[0072] Fig.10 summarizes the method for controlling the tilting block, including the calibration step for calibrating the incipient block position. In the block diagram of Fig.10 it is assumed that the detection of the caliper-block member interaction position is performed every time the tilting block device 51 is activated, but this is not the only possible solution, as mentioned above. [0073] Under certain circumstances, the jaws 55A, 55B of the caliper 55 may touch the block member before having achieved the incipient block position. A situation of this kind can occur, for example, due to the accumulation of dirt or debris between the block member and the active surfaces 551 A, 55 IB of the pads 552A, 552B of the jaws 55 A, 55B. In other cases, an anomalous situation of this kind can occur due to the incorrect reassembly of the members of the tilting block system following maintenance or cleaning interventions, or for any other reason.

[0074] In particularly advantageous embodiments, in order to avoid, or to eliminate, a situation of this kind, a control of the interaction between the caliper 55 and the block member 53 is provided in the step of approaching the incipient block position. Basically, through the caliper-block member interaction sensor 75, any premature interaction between the caliper 55 and the block member 53 before the incipient block position has been achieved, or when the incipient block position has been achieved, is detected. Basically, in this case, the interaction sensor 75 indicates to the control unit 71 a mutual interaction between the caliper 55 and the block member 53 before, or when, the incipient block position has been achieved. If a premature interaction occurs, the control unit 71 can stop the approaching movement toward the incipient block position and control, a small backward movement of the caliper 55, if necessary. The new position reached by the caliper can be stored as new incipient block position.

[0075] The check described above is combined with that already described with reference to Fig.10. The process with the double check of the interaction between the caliper 55 and the block member 53 is summarized in the flowchart of Fig.l 1.

[0076] Basically, in this case a step of calibrating the incipient block position is provided, which can be carried out before and/or during the approach of the caliper to the pre-stored incipient block position, or after the caliper 55 has achieved the tilting block position With this system it is possible to correct any drifts, with respect to the pre-stored incipient block position, both in the case of a premature stop (at an excessive distance) of the jaws 55A, 55B relative to the block member 53, and in the case of a premature contact between the jaws and the block member.

Claims

1. A tilting saddle-riding motor vehicle comprising: two front steered wheels and at least a tilting four-bar linkage connecting the front steered wheels to a frame; a block member integral with a component of the tilting four-bar linkage; a caliper co-acting with the block member and adapted to block the tilting four-bar linkage relative to the frame; a caliper control actuator; a control unit functionally connected to the caliper control actuator; wherein the control unit is adapted to control a pre-approaching movement of the caliper towards the block member based on a motor vehicle ride parameter, the preapproaching movement bringing the caliper from a completely open position to a position of incipient block of the tilting movement relative to the block member.

2. The motor vehicle of claim 1, wherein the motor vehicle ride parameter is a driving speed of the motor vehicle; wherein the control unit is adapted to control the pre-approaching movement when the motor vehicle driving speed is lower than a minimum threshold value.

3. The motor vehicle of claim 1 o 2, wherein the control unit is adapted to perform a step of calibration of the incipient block position when the caliper is brought to an anti-tilting position.

4. The motor vehicle of claim 1, 2 or 3, further comprising a caliperblock member interaction sensor; wherein the interaction sensor is adapted to detect a quantity indicative of the caliper-block member interaction; and wherein the control unit is functionally connected to the interaction sensor and is adapted to perform a step of calibration of an incipient block position based on the quantity indicative of the caliper-block member interaction.

5. The motor vehicle of claim 4, wherein the quantity indicative of the caliper-block member interaction is a function of a distance between an active surface of the caliper and the block member.

6. The motor vehicle of claim 4 or 5, wherein the control unit is adapted to store a position of the caliper control actuator detected by a position sensor, when the quantity indicative of the caliper-block member interaction has a value associated with a condition of incipient block of the tilting movement.

7. The motor vehicle of claim 4 or 5 or 6, wherein the caliper control actuator is an electric actuator.

8. The motor vehicle of claim 7, wherein the quantity indicative of the caliper-block member interaction is a function of a current absorbed by the caliper control actuator.

9. The motor vehicle of claim 8, wherein the quantity indicative of the caliper-block member interaction is a time derivative of the current absorbed by the caliper control actuator.

10. The motor vehicle of claim 9, wherein the control unit is adapted to detect the incipient block position when the derivative of the current absorbed by the caliper control actuator exceeds a threshold value.

11. The motor vehicle of one or more of claims 4 to 6, wherein the caliper-block member interaction sensor comprises one of the following: a load sensor adapted to detect a force exchanged between the block member and the caliper; a sensor of proximity of an active surface of the caliper to the block member.

12. A method for controlling a block of the tilting movement of a tilting saddle-riding motor vehicle, comprising: two front steered wheels and at least a tilting four-bar linkage connecting the front steered wheels to a frame; a block member integral with a component of the tilting four-bar linkage; a caliper co-acting with the block member and adapted to block the tilting four-bar linkage relative to the frame of the motor vehicle; the method comprising the following steps: detecting a motor vehicle ride parameter; and based on the ride parameter, actuating a caliper control actuator and performing a pre-approaching movement of the caliper towards the block member, bringing the caliper from a completely open position to a position of incipient block of the tilting movement with respect to the block member.

13. The method of claim 12, wherein the ride parameter is a driving speed of the motor vehicle, and wherein the pre-approaching movement is performed when the motor vehicle driving speed is lower than a minimum threshold value.

14. The method of claim 12 or 13, further comprising a step of calibration of the incipient block position when the caliper is brought to an antitilting position.

15. The method of claim 14, wherein the step of calibration of the incipient block position comprises the following steps: actuating the caliper to block the tilting movement; when the caliper performs a closing movement to clamp the block member, detecting a quantity indicative of the caliper-block member interaction; and storing, as incipient block position, a position of the caliper actuator based on the quantity indicative of the caliper-block member interaction.

16. The method of claim 15, wherein the quantity indicative of the caliper-block member interaction is a function of a distance between an active surface of the caliper and the block member.

17. The method of one or more of claims 12 to 16, wherein the caliper control actuator is an electric actuator, and wherein the quantity indicative of the caliper-block member interaction is a function of a current absorbed by the caliper control actuator.

18. The method of claim 17, wherein the quantity indicative of the caliper-block member interaction is a time derivative of the current absorbed by the caliper control actuator.

19. The method of claim 18, wherein the incipient block position is the caliper position where the derivative of the current absorbed by the caliper control actuator exceeds a threshold value.

20. The method of one or more of claims 12 to 16, wherein the quantity indicative of the caliper-block member interaction is one of the following: a force exchanged between the caliper and the block member; a distance between an active surface of the caliper and the block member.