DESCRIPTION

[0001] The present invention relates to the technical field of motor vehicles and in particular relates to an accelerator for a motor vehicle provided with a steering handlebar and a vehicle comprising said accelerator.

[0002] Various accelerators for motor vehicles provided with a steering handlebar, such as scooters, motorcycles, quads, tricycles, etc. are known of. Such accelerators normally comprise a knob, called the accelerator knob, rotatably coupled to the steering handlebar to be placed in rotation by the driver in order to control the power delivered by the vehicle engine.

[0003] In a vehicle with an internal combustion engine, the accelerator controls the opening of a throttle valve feeding the engine and thus allows the driver to control the engine power delivered.

[0004] Traditionally, for a long time in vehicles with internal combustion engines the accelerator knob has been connected to the throttle valve by mechanical connection systems such as cables, links and levers. Most vehicles with steering handlebars currently available still adopt this type of solution.

[0005] Vehicles of the "drive by wire" type have also been proposed in which the accelerator knob is connected via an electromechanical and electronic system to the throttle valve, so that the power delivered by the engine is de facto controlled by an electrical signal bearing information related to the angle of rotation of the knob with respect to a neutral rest position, wherein with the motor on, this is controlled by an electronic control unit to deliver a positive but minimum power or even null in a system of the start & stop type, in the latter case the engine being off when the knob is in the neutral, rest position.

[0006] The same considerations described above for vehicles with internal combustion engines also apply in the case of vehicles with electric traction motors or hybrid propulsion units.

[0007] In use, the known accelerators described above force the driver to keep the wrist rotated while the vehicle is travelling, in a position offset with respect to the axis of the forearm. This position may be anatomically uncomfortable and may also make a driving style providing for the alternate actuation in close temporal succession, or even almost simultaneous, of the brake lever attached to the handlebar on the side of the accelerator knob and the accelerator itself difficult or impossible. [0008] A general object of the present invention is to provide an accelerator for a motor vehicle comprising a steering handlebar which resolves entirely or at least in part the drawbacks discussed above with reference to the accelerators of the prior art.

[0009] These and other purposes are achieved by an accelerator as defined in claim 1 in its most general form, and in the dependent claims in some of its particular embodiments.

[0010] The present invention also relates to a vehicle as defined in claim 16.

[0001] The invention will be clearer to understand from the following detailed description of its embodiments, made by way of a non-limiting example with reference to the appended drawings, wherein:

- Fig. 1 shows a plan view in front elevation of an example of a vehicle comprising a steering handlebar;

-Fig. 2 shows a schematic plan view in lateral cross- section of a first embodiment of an accelerator coupled to the steering handlebar of the vehicle in figure 1 ;

-Fig. 3 shows a schematic plan view of the accelerator in figure 2 in which the accelerator is coupled to the steering handlebar of the vehicle in figure 1;

Fig. 4 shows a schematic view with detached parts, of the accelerator and of the steering handlebar in figures 2 and 3 in which some parts of figures 2 and 3 have been omitted;

Fig. 5 shows a schematic view with detached parts, of a steering handlebar and an accelerator according to a second embodiment; and

Fig. 6 shows a schematic view with detached parts of a further embodiment of the accelerator.

[ 0002 ] In the appended drawings, elements which are the same or similar will be indicated using the same reference numerals.

[ 0003 ] In the following description the terms front, rear, left, right, are intended with reference to the normal direction of travel of the vehicle.

[ 0004 ] With reference to the appended figures, a motor vehicle with the steering handlebar is globally denoted by reference numeral 1. In the example, the motor vehicle 1 is in particular a motorcycle.

[ 0005 ] It should be noted however that the teachings of the present description are not limited to a motorcycle but in general are applicable in general to motor vehicles comprising a steering handlebar. For example, the teachings of the present description are also applicable to scooters, motorcycles with three wheels, two of which are two front steering wheels, lightweight commercial vehicles for transport of goods with two rear wheels and a front steering wheel, quads, electric bicycles and pedal-assisted bicycles etc.

[0006] The vehicle 1 comprises a back-carriage 7 comprising a rear wheel 8. In a manner known per se, a steering fore-carriage comprising a steering handlebar 2, a fork 11, a front wheel 9 and two suspensions 12 is rotatably hinged to the back-carriage 7.

[0007] The vehicle 1 comprises a motor 10, which in the example is an internal combustion engine. In an alternative embodiment, the motor 10 may be an electric motor or in a further embodiment, the engine 10 could be replaced by a hybrid propulsion unit, comprising at least one electric motor and at least one internal combustion engine .

[0008] To a first end portion 5 of the steering handlebar 2 a first manual control group, comprising an accelerator 3 and a brake lever 6 is coupled. The accelerator 3 comprises an accelerator knob 4.

[0009] To a second end portion 15 of the steering handlebar 2, opposite the first end portion 5, a second manual control group is coupled comprising a gripping knob 14 and a lever 16, which in the example is an actuation lever of the clutch of the engine 10.

[0010] In normal use of the vehicle 1, the first manual control group is preferably operable by the driver with the right hand while the second manual control group is preferably operable by the driver with the left hand. Preferably, the gripping knob 14 of the second manual control group is only an ergonomic gripping knob while the knob 4 of the first command group in addition to being an ergonomic gripping knob is an accelerator knob, i.e. which allows the driver to control the power output from the engine 10.

[0011] The aforementioned manual control groups may comprise further control elements such as switches, deviators for example provided to control the indicator lights, a horn, lighting units etc.

[0012] In the particular, non-limiting example shown in figures 1 to 4 the steering handlebar 2 comprises a main shaped and tubular body, to the end portions 5 and 15 of which the first and the second manual control groups are respectively attached.

[0013] The accelerator 3 comprises a reaction torque transducer 20 adapted to receive torsional stresses due to a torsional force applied by a driver of the vehicle 1 to the accelerator knob 4 and to produce an electrical control signal of the power delivered by the motor 10.

[0014] In contrast to a rotary torque transducer, a reaction torque transducer has a rigid structure without rotating parts. So, in the present case, the reaction torque transducer 20 comprises a rigid structure adapted to oppose the rotation of the accelerator knob 4. For the purposes of the present description, the term rigid structure is taken to mean a structure devoid of parts with rotational movement except for small residual movements due to the residual elasticity of the materials .

[0015] With reference to figures 2,4 and 5, according to one embodiment the reaction torque transducer 20 comprises a body 20', cylindrical in the example, having a first end portion 21 fixed to the steering handlebar 2 and a second opposite end portion 22 fixed to the accelerator knob 4. In the example shown in the figures, the body 20' has a cylindrical shape. Moreover, in the example shown in the figures the first and the second end portions 21 and 22 are two opposite cylindrical pins 21, 22 that protrude from opposite sides of the body 20' . In an alternative embodiment the end portions 21 and 22 may be coupling flanges instead of being cylindrical pins. Moreover, in the particular example shown and thereby without introducing any limitation, the cylindrical pins 21, 22 are each provided with a respective recess 27, 28 to be respectively attached by attachment elements 25, 26, for example screws in the case of reversible attachment or rivets in the case of irreversible attachments, respectively to the steering handlebar 2 and to the accelerator knob 4.

[0016] In the examples shown in the figures, to allow attachment of the first end portion 21 of the reaction torque transducer 20 to the steering handlebar 2, the steering handlebar 2 comprises a reaction bracket 51, fixed, for example welded, to the steering handlebar 2, provided with a coupling seat 52 adapted to receive the first end portion 21. Moreover, in the example shown the aforementioned coupling seat comprises a through hole crossed by an attachment element 25 suitable to lock the first end portion 21 of the reaction torque transducer 20 so as to prevent a rotation of the end portion 21.

[0017] With reference to figure 4, according to one embodiment, the vehicle 1 with a motor 10 comprises an electronic control unit 60 comprising an input port 61 of the signal and the accelerator 3 comprises an output port of the signal 29 on which said electric signal is supplied and which is adapted and configured to be operatively connected to the input port of the signal 60 of the electronic control unit, for example by means of a wired multipolar connection 65. In the particular example shown, the output port of the signal 29 comprises a connector fixed to the body 21' of the reaction torque transducer 20. [0018] Preferably, the electrical signal supplied in output by the reaction torque transducer 20 is an analogue output signal having a voltage with an amplitude proportional to the torsional stress received by the aforesaid torque transducer 20. More preferably, the reaction torque transducer 20:

- is such as to receive, for example via the multipolar wired connection 65, an analogue input signal in DC voltage having an amplitude;

- comprises a transformation circuit of the amplitude of the voltage sensitive to the torsional stresses and adapted to produce the analogue output signal starting from the analogue input signal.

[0019] For example, the aforesaid transformation circuit of the amplitude of the voltage comprises a Wheatstone bridge comprising resistor elements, such as for example strain gauges, whose resistance depends on the dimensional deformations caused by the torsional stresses .

[0020] Although it is possible to provide for a first embodiment where a rigid connection between the accelerator knob 4, the transducer 20, and the steering handlebar 20 is such as to prevent a rotation of the knob 4, it is possible to provide for a second embodiment in which the accelerator 3 comprises a coupling system with angular clearance adapted to permit a free rotation of the accelerator knob 4 with respect to the steering handlebar according to a limited angle starting from a rest position, so that an initial force applied to the acceleration knob 4 does not produce torsional stresses applied to the reaction torque transducer 20 and is thus not translated into an acceleration demand for the motor. Once the accelerator knob 4 has been rotated by an amount equal to the aforesaid limited angle starting from the rest position, thus reaching a limit angular position opposite the limit angular position corresponding to the rest position, a further force attempting to produce a rotation in the same direction is such as to impart stresses to the reaction torque transducer 20 and does not cause a further rotation of the knob 4 in that the latter reacts via the transducer 20 on the steering handlebar 2. Elastic return means may also be provided which tend to return the accelerator knob 4 to the rest position. For example, the aforesaid limited angle is less than or equal to 20°, preferably less than or equal to 10°, more preferably less than or equal to 5°.

[0021] According to one embodiment the accelerator knob 4 comprises an attachment element 48 of a brake lever 6 to the accelerator knob 4. It is thus possible to make a manual control group in which the brake lever 6 is not directly attached to the steering handlebar 2 being attached to the accelerator knob 4 in turn attached to the steering handlebar 2. The aforesaid attachment element 48 is for example an attachment collar.

[0022] According to one embodiment, the accelerator knob 4 comprises a covering sheath 40, for example rubber, and a support core 41 at least partially covered by the covering sheath 40. The support core 41 comprises a shaft 42 having a first end portion 43 attached to the reaction torque transducer 20. The attachment element 48 of the brake lever 6 can thus be attached to the support core 41 for example it may be a collar pulled tight around the support core 41. In the embodiment in figures 2 and 3 an attachment element 49 is also provided for, such as a collar 49 which can be clamped between clamping elements 59, such as screws or pins, to the support core 41.

[0023] In the embodiment in figures 1 and 4, the aforesaid support core 41 comprises an inner cavity 45 provided with a bottom wall 46 and in which the end portion 5 of the steering handlebar 2 is engaged/engageable ; the aforesaid end portion 5 of the steering handlebar 2 is internally hollow and the shaft 42 at least partially passes through said end portion 5 of the internally hollow steering handlebar 2 and has a second end portion 44 fixed to said bottom wall 46 and opposite the first end portion 43 of the shaft 42 fixed to the reaction torque transducer 20. For example as shown in figure 2, the accelerator 3 comprises a coupling flange 23 attached by screws or rivets 24, 26 to the end portion 43 of the shaft 41 and the second end portion 22 of the reaction torque transducer 20. For example the aforesaid coupling flange 43 is a conical flange in the case in which the second end portion 22 has a cross section having an area different from the area of the cross section of the end portion 43 of the shaft 41.

[0024] Again with reference to figures 2-4, in the non- limiting embodiment shown therein the reaction torque transducer 20 is placed outside the steering handlebar 2 and the steering handlebar 2 comprises a tubular wall provided with a through hole 50 made on said wall and crossed by said shaft 42 to allow said first end portion 43 of the shaft 41 to jut outside said tubular wall and thus be attached to the second end portion 22 of the reaction torque transducer 20.

[0025] In an alternative embodiment to that described above, the reaction torque transducer 20 is arranged inside the internally hollow end portion 5 of the steering handlebar 2.

[0026] With reference now to figure 5, a further embodiment is shown which differs from the embodiments described so far in that the steering handlebar 2 in this case does not have a tubular body being made by moulding of a metallic material, for example being made of cast aluminium. The reaction bracket 51 is for example made integrally with the steering handlebar 2 and the steering handlebar comprises two coupling seats 54, 55, for example made integrally in the steering handlebar 2, provided for the attachment to the handlebar respectively of the torque transducer 20 and the accelerator knob 4. For example, the aforesaid coupling seats 54, 55 are two cradle seats to which bridge attachment elements 56, 57 may be attached by means of screws or rivets (not shown in the figure) . It is also to be noted that in the example in figure 5, the shaft 42 and the support core 41 of figures 2-4 are the same thing and a joint is provided (for example, a bushing similar or equivalent to the flange 23 of the embodiment shown in figure 2) , not shown in the figure, to attach the end portion 43 of the shaft 42 (or support core 41) to the second end portion 22 of the torque transducer 20.

[0027] With reference to Figure 6, in a further embodiment, in alternative to joint described above, which is for example rigid, it is possible to provide a resilient coupling element 60, for example a helical spring, interposed between the reaction torque transducer 20 and the accelerator knob 4, for example having an end portion coupled to the reaction torque transducer 20 and an opposite end portion coupled to the accelerator knob 4. Said resilient coupling element 60 is both subject to torsional deformation and is such as to transmit torsional stresses to the reaction torque transducer 20. In this way advantageously, the resilient element is such to adsorb at least in part the torsional force applied through the rotation of the knob 4 to the transducer 20, allowing to better modulate the applied force.

[0028] In addition or alternatively, the resilient coupling element 60 may be provided between the reaction torque transducer 20 and the steering handlebar 2, for example between the transducer 20 and the bracket 51. In the above cases described above, the acceleration knob 3 is such as to rotate with respect to the reaction torque transducer and preferably said rotation occurs according to a limited angle, limiter either by the same elastic deformability of the resilient element in relation to the forces normally applied by a hand of a driver who acts on the acceleration knob 4 or by the presence of one or more of stopping elements adapted to stop a rotation of the knob 4. For example, the aforementioned limited angle is less than or equal to 20°, preferably is less than or equal to 10°, more preferably less than or equal to 5°. It must be observed that the variant embodiment described with reference to Figure 6 is also applicable to the embodiment of Figures 1-4, by providing a resilient coupling element 6 operatively interposed between the shaft 42 and the reaction torque transducer 20 and/or between the reaction torque transducer 20 and the steering handlebar 2, for example between the reaction torque transducer 20 and the bracket 51. It must be observed that the embodiments described above have in common the fact that the accelerator 3 comprises a resilient element operatively interposed between the acceleration knob 4 and the reaction torque transducer 20 and/or between the reaction torque transducer 20 and the steering handlebar 2. By suitably selecting the structural features of the resilient element in terms of shape, size and elastic constant and/or providing at least stop element for stopping the rotation of the accelerator knob 4 is possible to render the accelerator knob 4 rotatable with respect to the steering handlebar around a knob according to a limited angle. For example, the above mentioned limited angle is less than or equal to 20°, preferably less than or equal to 10°, more preferably less than or equal to 5°.

[0029] It should be observed that a limited rotation of the knob 4 in combination with the presence of a reaction torque transducer 20 advantageously allows to simplify the electronic throttle control 3 since with respect to, systems totally free of rotating parts it enables to better distinguish the voluntary torsional stresses applied to the torque transducer 20 from those that are not intentional, thereby increasing the security of the system .

[0030] On the basis of the above description, it can therefore be seen how an accelerator according to the present description makes it possible to fully or at least in part achieve the aforementioned purposes.

[0031] An accelerator as described allows the driver to maintain a comfortable wrist position while driving and also makes it possible to quickly switch between braking and acceleration or even to brake and accelerate simultaneously .

[0032] Lastly, it should be noted that an accelerator as described above may be part of a drive-by-wire system of a vehicle.

[0033] Without prejudice to the principle of the invention, the embodiments and construction details may be varied widely with respect to what has been described and illustrated purely by way of a non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.