The present invention relates to the field of automotive applications. In particular, the present invention relates to a suspension tilting module for wheeled vehicles and a wheeled vehicle equipped with such a suspension tilting module. In more detail, the present invention relates to a suspension tilting module allowing at least two wheels of a vehicle disposed on a common axle to be tilted together with the whole body of the vehicle. Still in more detail, the present invention relates to a suspension tilting module allowing both tilting and vertical displacement of said two wheels. Furthermore, the present invention relates to a suspension tilting module allowing it to adequately absorb shocks to which one or both of the two wheels are subjected, for instance, when one or both of the two wheels crosses a bump. Still in more detail, the present invention relates to a suspension tilting module equipped with hydraulic actuating means adapted to provide the torque needed for the tilting function. Finally, the present invention relates to a tilting module equipped with hydraulic actuating means exerting a torque on a tilting arm pivotally connected to a rigid frame which is in turn adapted to be firmly fixed to the chassis of the vehicle.
Over the past few years, interest has grown towards vehicles with innovative configurations due to the increasing number of vehicles and the related problems of traffic congestion and pollution. Such vehicles are usually of small weight and size to minimize parking problems and to reduce losses due to rolling resistance and aerodynamic drag. In particular, the size of these vehicles is normally designed for one or two people, thus allowing for personal mobility. Moreover, the small size and weight of these vehicles allows for a reduction in engine power and, accordingly, emissions without compromising performance.
In particular, over the past years, many efforts have been devoted by car manufacturers to the development of so-called tilting vehicles, namely vehicles wherein all or part of the vehicle is inclined inward during cornering so that gravity and centrifugal forces are kept oriented along the vertical body axis of the vehicle. In other words, tilting vehicles are characterized by the capacity to bank over to the side like a motorbike or motorcycle. Accordingly, rollover can be avoided even if the track of the tilting vehicle is narrow with respect to that of conventional vehicles.
Several tilting vehicles have been proposed in the past with three or more wheels. In some three wheeled vehicles, the tilting is provided just to the body and the central wheel while the axis with two wheels does not tilt. On the contrary, in other cases, the solution is preferred according to which all wheels tilt with the body, since this solution allows for improved performance of the vehicle.
However, in spite of all the advantages offered by tilting vehicles, the further development of these vehicles has revealed that several problems have still to be solved or overcome. The tilting vehicles known in the art may be classified in essentially two categories, namely vehicles with manual tilting and vehicles with automated or active tilting where the tilting function is carried out by adequate actuating means driven by a control system. In manual tilting vehicles, the tilting command to the suspension system is provided by the driver. On the contrary, in the case of automated tilting an the use of actuating means, the tilting function is exploited by tilting actuators following a command of the driver and/or under the control of a control system adapted to collect information or data relating to either the driving conditions and/or the behavior of the vehicle and to generate corresponding commands which are then sent to the actuators. In particular, active tilting vehicles usually comprise a tilting suspension module and/or system wherein moving suspension elements are connected to a tilting actuator so that the motion of the tilting actuator controls the amount of tilting imposed on the vehicle. Moreover, a control system sends commands to the tilting actuator, with the commands being generated as a function of information relating to either the driving condition and/or the behavior of the vehicle collected by the control system.
However, providing tilting actuating means and/or devices adapted to adequately carry out the tilting function has revealed to be a very difficult task. For this reason, several actuating means have been proposed in the prior art. For instance, electromechanical actuating means have been proposed essentially based on electric motors mechanically coupled to a tilting mechanism by means of mechanical transmission means such as, for instance, transmission belts, mechanically interposed between one or more electric motors and a reduction gear. In this case, the tilting torque can be easily controlled by controlling the electrical current supplied to the electric motor while the mechanical gearbox is used to amplify the motor output torque.
Although there are evident advantages offered by electromechanical actuating means, it has to be appreciated that the electromechanical actuating means are still affected by several drawbacks. For instance, when a large reduction ratio is required between the rotational displacement of the electric motor and the rotational displacement of the reduction gear, the overall dimensions and the volume of the reduction gear increase drastically, so that it becomes difficult to conveniently position the reduction gear inside the vehicle. Accordingly, it becomes difficult to obtain a convenient layout of the vehicle. Moreover, due to the mechanical link between the electric motor and the tilting mechanism, the electric motor and the reduction gearbox have to be positioned into proximity of the tilting mechanism resulting in the total allowable tilting angle being limited and/or reduced, so that the tilting function may in some cases will not be satisfactory. Furthermore, a further drawback affecting the tilting vehicles equipped with an electromechanical tilting system relates to the fact that the overall mass and weight of the vehicle drastically increases, resulting in the tilting function being slowed down so that the vehicle is not tilted as quickly as required with corresponding problems arising, for instance in the case of emergency situations. Moreover, friction arises in the mechanical reduction gearbox, resulting in the efficiency of the actuating means being reduced and electric motors with increased performance, with increased overall dimensions and weight, being required. Moreover, the mechanical transmission may generate noise and/or vibrations resulting in a decreased driving comfort for the driver. Finally, due to the overall dimensions and weight of the known electromechanical actuating means, it becomes impossible to provide emergency actuating means adapted to provide the needed actuating torque in the case of failure of the main actuating means so that the vehicle no longer behaves as a tilting vehicle. For instance, in the case were the supply of electrical current to the electric motors is interrupted. Finally, regular inspections and/or maintenance operations are needed for the purpose of checking the mechanical transmissions, thus resulting in increasing overall maintenance costs for the vehicle. Accordingly, in view of the problems and/or drawbacks identified above, it would be highly convenient to provide a suspension tilting module that overcome the drawbacks affecting the prior art tilting solutions.
In particular, it is an object of the present invention to provide a suspension tilting module for a wheeled vehicle allowing it to overcome the problems affecting the prior art tilting modules and/or systems of the kind equipped with electromechanical actuating means.
A further object of the present invention is that of providing a suspension tilting module equipped with actuating means which do not require any mechanical link between the power source providing the tilting torque and the tilting mechanism.
Still another object of the present invention is that of providing a suspension tilting module equipped with actuating means comprising a power source adapted to provide the tilting torque wherein the power source may be positioned and/or disposed at some distance from the suspension module, thus allowing improvement in the overall layout of the vehicle implementing this suspension tilting module.
Still a further object of the present invention is that of providing a suspension tilting module equipped with actuating means with reduced overall dimensions and weight, in particular, with overall dimensions and weight which are less than those of electromechanical actuating means.
Another object of the present invention is that of providing a suspension tilting module equipped with actuating means generating a reduced friction, in particular a friction which is less than that arising in the case of electromechanical actuating means.
Still a further object of the present invention is that of providing a suspension tilting module equipped with actuating means allowing the suspension tilting module to be transformed into a manually actuated suspension tilting module.
Moreover, a further object of the present invention is that of providing a suspension tilting module equipped with a redundant actuating system, namely an actuating system comprising main actuating means and emergency actuating means, wherein the emergency actuating means may start working in the case of failure of the main actuating means.
A further object of the present invention is that of providing a suspension tilting module equipped with active actuating means of reduced dimension, complexity and weight and adapted to work not only to brake the tilting system but also to actively carry out the tilting function.
To this end, according to the present invention, this is obtained by providing a suspension tilting module equipped with hydraulic actuating means adapted to actively exploit the tilting function, that is, hydraulic actuating means adapted to provide the tilting torque needed for tilting the suspension system.
In particular, according to a first embodiment of the present invention, a suspension tilting module is provided, namely a suspension tilting module for a wheeled vehicle comprising at least two wheels disposed on a common axle, the module comprising a suspension system adapted to support the at least two wheels allowing tilting of the at least two wheels, wherein the suspension tilting module comprises a rigid frame adapted to be firmly fixed to the chassis of he vehicle and pivotally supporting a tilting arm. The module further comprises hydraulic actuating means pivotally interposed between the rigid frame and the tilting arm, so that activation of the hydraulic actuating means results in a force being exerted on the tilting arm and the rigid frame being tilted together with the at least two wheels.
According to a further embodiment of the present invention, a suspension tilting module is provided, namely a module wherein the tilting arm comprises at least a first arm portion and wherein the hydraulic actuating means comprise at least a first hydraulic actuator adapted to exert a force on the at least first arm portion.
Still according to another embodiment of the present invention, a suspension tilting module is provided, namely a suspension tilting module wherein the at least first hydraulic actuator comprises a hydraulic cylinder.
According to still another embodiment of the present invention, a suspension tilting module is further provided, namely a suspension tilting module wherein the tilting arm comprises a second arm portion and wherein the hydraulic actuating means comprise a second hydraulic actuator adapted to exert a force on the second arm portion.
According to still a further embodiment of the present invention, a suspension tilting module is provided, namely a module further comprising at least one hydraulic pump hydraulically connected to the hydraulic actuating means.
According to further embodiment of the present invention, a suspension tilting module is also provided, namely a suspension tilting module further comprising at least one electric motor adapted to drive the at least one hydraulic pump.
Still according to a further embodiment of the present invention, a suspension tilting module is also provided, namely a suspension tilting module wherein the tilting arm is pivotally connected to a first shock absorber and a second shock absorber through pivotable connections, respectively.
According to the present invention, there is also provided a driving tilting suspension system, namely a driving tilting suspension system comprising a suspension tilting module along with two wheels rotatably connected to said module.
According to a further embodiment of the present invention, a driving tilting suspension system is further provided, namely a driving tilting suspension system further comprising at least one electronic control unit adapted to collect data relating to the driving condition and/or the behavior of the vehicle and to emit electrical signals as a result of the collected data.
According to another embodiment of the present invention, a wheeled vehicle is provided, namely a vehicle comprising at least two wheels, the vehicle being equipped with a driving tilting suspension system according to the embodiments of the present invention.
Further embodiments, features or details of the present invention are more fully described and defined in the following more detailed description.
In the following, a description will be given with reference to the drawings of particular and/or preferred embodiments of the present invention. It has, however, to be noted that the present invention is not limited to the embodiments disclosed but that the embodiments disclosed only relate to particular examples of the present invention, the scope of which is defined by the appended claims. In particular, in the drawings:
While the present invention is described with reference to the embodiments as illustrated in the following detailed description as well as in the drawings, it should be understood that the following detailed description as well as the drawings are not intended to limit the present invention to the particular illustrative embodiments disclosed, but rather that the described illustrative embodiments merely exemplify the various aspects of the present invention, the scope of which is defined by the appended claims.
As apparent from the disclosure given above, the present invention is understood to be particularly advantageous when used for applications in the automotive field; in particular, the present invention is understood to be particularly advantageous when applied to the steering wheels of vehicles. For this reason, examples with be given in the following in which corresponding embodiments of the tilting module and/or system according to the present invention are described in combination with steering wheels. However, it has to be noted that the present invention is not limited to the particular case of a tilting module and system for steering wheels, but can be used in any other situation in which two wheels of a vehicle disposed on a common axle need to be tilted. Accordingly, it will become apparent from the following disclosure that the present invention may also be used for automotive applications in which, for instance, the steering wheels are not tilted. Moreover, even if those examples of wheeled vehicles disclosed in the present application and implementing the present invention mostly relates to cars driven by a main combustion engine, it has to be understood that the possible implementations of the tilting module and system according to the present invention are not limited to these kind of vehicles; on the contrary, the tilting module and system according to the present invention may also be conveniently implemented in different vehicles such as, for instance, tracks, trains, tractors or the like.
The present invention is based on the principle that adequate tilting can be conveniently obtained by active hydraulic actuating means adapted to generate the torque needed for tilting the vehicle. In particular, the present invention is based on the principle that hydraulic actuating means may be used instead of mechanical and/or electromechanical actuating means for the purpose of generating the required tilting torque. In more detail, the present invention is based on the principle that if the hydraulic actuating means are used in combination with an electric motor and an electric pump, with the electric motor driving the hydraulic pump and with the hydraulic pump driving the hydraulic actuating means, the hydraulic actuating means may be used to multiply the torque provided by the electric motor in order to obtain the required tilting torque. Accordingly, the proposed solution exploits the large reduction ratios that can be obtained by hydraulic systems. Moreover, the tilting force or torque may be controlled by the electric motor torque, without any need of any servo valve; accordingly, the system is adapted to work with a fixed volume of hydraulic fluid so that a fluid reservoir is needed only for the purpose of compensating for the unavoidable leakages. Furthermore, the system may be regarded as a by-wire system, since all the functions of the system may be controlled by an electronic control unit and a power electronic unit, in combination, with the electronic control unit being adapted to collect data relating to the driving conditions and/or the behavior of the vehicle and to provide the power electronic unit with corresponding signals allowing the power electronic units to drive the electric motor and, accordingly, the overall tilting actuating system. Moreover, if an isolation valve is used, this isolation valve may be used to isolate the hydraulic actuators from the rest of the actuating means, for instance from the hydraulic pump, so that the active tilting module can be transformed into a manually actuated tilting module. Moreover, isolating the hydraulic actuators from the hydraulic pump by means of the isolation valve also allows blocking the tilting module at a predefined position so as to avoid any tilting of the module which is, therefore, transformed in a fixed, non-tilting suspension module.
In the following with reference to
As apparent from
By way of example, said first and second hydraulic actuating means 102 and 101 may comprise first and second hydraulic cylinders, respectively, for instance single effect hydraulic cylinders, namely hydraulic cylinders adapted to exert a force only along a unique predefined direction. Alternatively, said first and second hydraulic cylinders 102 and 101 may comprise double effect hydraulic cylinders namely hydraulic cylinders adapted to exert a force along a first predefined direction and along a second predefined direction substantially contrary to the first predefined direction. When double effect hydraulic cylinders are selected, a unique hydraulic double effect cylinder may be used, for instance the first hydraulic cylinder 102 depicted in
The hydraulic actuating means 102 and 101 may be actuated by means of a pump, for instance a fixed displacement hydraulic pump driven by one or more electric motors. While a detailed description of the electromechanical layout of the tilting module and system according to the present invention will be given in the following with reference to
The suspension structure system of the tilting module of the present invention according to the embodiment depicted in
The suspension structure further comprises a first steering arm or upright 9 adapted to rotatably support a first wheel 2, as well as a second steering arm or upright 8 adapted to rotatably support a second wheel 3. The first upright 9 is supported by the first upper arm 12 and the first lower arm 13. In particular, the first upright 9 is pivotally connected to the first upper and lower arms 12 and 13 through pivotable connections 9a and 9b, respectively. In the same way, the second upright 8 is supported by the second upper arm 10 and the second lower arm 11; in particular, the second upright 8 is pivotally connected to the second upper arm 10 an the second lower arm 11 through pivotable connections 8a and 8b, respectively. The pivotable connections 9a, 9b, 8a and 8b allow both steering and tilting of the two wheels 2 and 3. Two motors 4 and 5 may be received in the hubs of the wheels 3 and 2, respectively as illustrated in
In the following, a description will be given with reference to
As apparent from
When the system operates under normal conditions, the electric motor 108 provides torque to the hydraulic pump 112 under the control of the power electronic power units 110 and the electronic control unit 111. For instance, to this end, the electronic control unit 111 may be conceived so as to be adapted to collect data relating to the behavior of the vehicle and/or the driving conditions. Such as, for instance, data relating to the speed of the vehicle or the lateral acceleration in case of turning or lateral wind or the like, and to supply corresponding signals to the power electronic unit 110 as a function of the data collected. In this way, the electric motor 108 may be adequately driven by the power electronic unit 110. For instance, the electric motor 108 may be driven so as to provide a predefined torque to the hydraulic pump 112, resulting in a predefined torque being exerted by the hydraulic actuating means 102 and 101 on the tilting arm 14. In the same way, the rotational speed of the electric motor 108 may be controlled, resulting in the hydraulic pump 112 being also driven at a predefined rotational speed so as to obtain a predefined actuation speed of one or both of the hydraulic means 102 and 101. The torque produced by the electric motor 108 drives the rotation of the hydraulic pump 112 that pumps fluid from one hydraulic actuating means 102 to the other hydraulic actuating means 101, thus resulting in a tilting torque being exerted on the tilting arm 14.
As it will become more apparent with the following description, applying a tilting torque to the tilting arm 14 results in the tilting frame 17 to be tilted with respect to the tilting arm 14, thus resulting in the whole suspension module and the two wheels being tilted.
When the need arises to lock the tilting movement of the tilting module, for example at low speed or during parking of the vehicle implementing the tilting system, it is possible to close the intakes of the two hydraulic actuating means 102 and 101 by activating the isolation valve 105 so as to close the two ports connected to the two hydraulic actuating means 102 and 101. The two ports connected to the hydraulic pump 112 may be connected together, as represented in
It has to be noted that with the electromechanical layout depicted in
It has, furthermore, to be noted that several amendments and/or modifications of the electromechanical layout depicted in
In the following, with reference to
As soon as tilting of the vehicle implementing the tilting module and system depicted in
Accordingly, the rotation of the rigid frame 17 of an angle α, as illustrated in
It results, therefore, from the above that the tilting module and system according to the present invention is an active tilting module and system, namely a module and system wherein the tilting function is obtained through the action of hydraulic actuating means which may comprise one or more electric motors driving one or more hydraulic pumps. Alternatively, the tilting module may even be actuated manually.
It has, moreover, to be appreciated that rotating the rigid frame 17 by an angle α as depicted in
For the purpose of exploiting the tilting function, the vehicle implementing the tilting module and/or system according to the present invention may be equipped with sensing means adapted to collect data relating to the dynamic behavior of the vehicle so as to activate the electric motor 108 and the pump 112, in the case of the embodiment depicted in
When one of the two wheels 2 and 3 crosses a bump, the tilting module and/or system according to the present invention behaves as depicted in
In particular, in the embodiment of
Moreover, the way in which the vertical displacement of the wheel 2 is absorbed or compensated for by the shock absorber 18 may be summarized as follows. As depicted in
Although this behavior of the shock absorber 18 may be accepted in some circumstances, shock absorbing means with non-linear characteristics may be preferred in other circumstances such as, for example, in the case of light vehicles where the mass of the passengers and luggage is an important fraction of the overall mass of the vehicle. That is to say that shock absorbing means with a stiffness increasing with the load, i.e. with a stiffness increasing in a non-linear manner with the load may be preferred for the purpose of improving the comfort and the dynamics of the vehicle. In fact, shock absorbing means with a stiffness increasing with the load and/or the vertical displacement of the wheels may allow the keeping the natural frequency of the suspended mass to a fairly constant value. Moreover, shock absorbing means with a stiffness increasing non-linearly or more than proportionally as a function of the vertical displacement of the wheels may allow keeping the vertical displacement of the wheels lower than a predefined value, while this is not possible in the case of shock absorbing means where the stiffness is constant.
In the following, a first example of a vehicle implementing the suspension tilting module and system according to the present invention will be described with reference to
The vehicle 200 depicted in
The vehicle 200 may be of the kind comprising a main engine, not depicted in
A further example of a vehicle implementing a suspension tilting module and system according to the present invention will be described with reference to
The main difference between the vehicle of
The same considerations as stated above with respect to the vehicle of
It has, therefore, been demonstrated that the suspension tilting module and system according to the present invention overcomes the problems or drawbacks affecting prior art suspension tilting modules. In particular, the advantages offered by the suspension tilting module and system according to the present invention with respect to prior art suspension tilting module and systems may be summarized as follows.
The suspension tilting module and system according to the present invention have a very simple electromechanical and/or electro hydraulic layout, and does not have transmission belts and no hydraulic control is needed.
A better optimization of the vehicle layout implementing the suspension tilting module and system according to the present invention is also possible due to the more compact layout with respect to purely mechanical or electro mechanical modules and systems.
There is no need of any mechanical link between the electric motor and the tilting mechanism, so that the electric motor and the hydraulic pump can be positioned at some distance from the hydraulic actuating means, thus allowing optimization of the overall assembly of the vehicle implementing them.
The overall mass of the tilting module and system according to the present invention is less than that of common electro mechanical tilting modules and systems.
In the module and system according to the present invention, less friction forces arise than in common suspension tilting modules and systems.
The control of the tilting torque can be directly controlled with the current in the electric motor without any need for control valves.
The tilting module according to the present invention can be easily and quickly transformed into a manually actuated tilting module.
In the tilting module and system according to the present invention, electromechanical layouts are possible offering high power and control redundancy, for instance implementing two hydraulic chains that work in parallel; accordingly, complete fully redundant systems may be provided.
The suspension tilting module according to the present invention is an active electro hydraulic tilting module working not only to brake the tilting movement, but also to actively carry out the tilting function.
The actuating tilting system according to the present invention can be regarded as a by-wire system as it only comprises electrical connections between the control signal coming from the driver or the electronic control unit and the electric motor.
Of course, it should be understood that a wide range of changes and modifications can be made to the embodiments described above without departing from the scope of the present invention. It has, therefore, to be understood that the scope of the present invention is not limited to the embodiments described, but is rather defined by the appended claims.
Further modifications and variations of the present invention will be apparent to those skilled in the art in view of this description. Accordingly, the description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the present invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments.
Number | Date | Country | Kind |
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06012974.9 | Jun 2006 | EP | regional |