DESCRIPTION FIELD OF APPLICATION

[0001] This invention relates to an actuator device for a combined rear-front braking system for a motor vehicle, a combined rear-front braking system for a motor vehicle and motor vehicle thereof.

STATE OF THE ART

[0002] In particular, in the motor vehicle field it is known to provide combined braking systems, i.e., braking systems that, by actuating a single brake command (lever or pedal), allow automatically actuating, at least partially, both braking devices disposed on both rear and/or front axles respectively.

[0003] The purpose of combined braking is to maximise the use of tyre-road friction and increase braking performance .

PRESENTATION OF THE INVENTION

[0004] To solve the above problems, to date combine braking solutions have been adopted in the art that provide for the use of hydraulic actuator devices of the braking devices, which are typically disc brake callipers. The combined braking takes place for example by means of a hydraulic connection between the hydraulic actuation systems of said braking devices.

[0005] However, this solution is expensive and involves the use of hydraulic actuator devices on the motor vehicle (typical of disc brakes) that are more expensive than mechanical actuator devices (typical of drum brakes) .

[0006] The purpose of this invention is to provide a reliable and economical combined brake system for motor vehicles, comprising both hydraulically and mechanically actuated braking devices that can be easily applied, even on pre-existing systems.

[0007] Such combined braking systems typically comprise a drum brake, mechanically actuated and placed on the rear wheel or axle, and at least one hydraulically actuated disc brake disposed on the front wheel or axle.

[0008] As is known, the braking action exerted on the rear or axle is less effective than that exerted on the front wheel or axle that, due to deceleration and the load transfer on the front axle, is able to ensure much greater deceleration in complete safety, i.e., without the risk of locking the related wheel or axle.

[0009] Therefore, it is important that the braking action on the rear wheel or axle be combined, automatically, with the braking action on the front wheel or axle so as to always ensure a proper deceleration to the vehicle even in the event of actuation, by the user, of only the single actuator of the brake on the rear wheel or axle.

[0010] So, the need is felt to provide a combined braking system from the rear to the front that is reliable and economical and comprises at least one mechanically actuated brake and at least one hydraulically actuated brake .

[0011] This need is met by an actuator device for a combined rear-front braking system for a motor vehicle according to claim 1.

[0012] In particular, this need is met by an actuator device for a combined rear-front braking system for a motor vehicle comprising a device body that houses and guides a float mechanically connected to a first cable for the mechanical actuation of an associable first braking device, wherein the float defines an axial direction,

- a manual actuation lever or pedal, mechanically connected to said device body so as to command the translation, along said axial direction, of a first actuating stroke in a first actuating direction, and so as to translate the first cable and actuate the first braking device,

- wherein the device body delimits a hydraulic fluid chamber that houses said float suitable to put the fluid of said hydraulic fluid chamber under pressure, said chamber being fluidically connectable, by means of an output, to an associable second hydraulically-actuatable braking device, distinct from the first braking device, - wherein between the float and the device body are interposed elastic means so as to actuate the float and put the hydraulic fluid chamber under pressure as a result of the actuation of the actuating rod by means of the manual actuation lever or pedal,

- wherein the float and the first cable are parallel and in series along said axial direction.

[0013] According to an embodiment of this invention, the elastic means are arranged coaxially to the float, between a first shoulder of the device body and a plate integral with the float so as to be preloaded, and to influence the float in a rest condition in which the fluid in the hydraulic fluid chamber is not put under pressure by the float.

[0014] According to an embodiment of this invention, wherein the device body drags in translation, along the axial direction, the first cable in the first actuation direction, wherein the device body delimits a hydraulic fluid chamber that houses a float suitable to put the fluid of said chamber under pressure when translated with respect to the device body, in the axial direction, of a second actuation stroke, in a second actuation direction opposite to the first actuation direction.

[0015] According to an embodiment of this invention, the device body comprises elastic means that exert an elastic thrust on the float in the first actuation direction to maintain the device body and the float axially integral with each other, said elastic means opposing the actuation thrust of the actuating lever or pedal, wherein the float moves with respect to the device body of said second actuating stroke in the second actuation direction, when the thrust exerted on the device body by the actuating lever or pedal exceeds the elastic thrust exerted by elastic means.

[0016] According to an embodiment of this invention, the float comprises a first connection end to a connection bush of the first cable so as to be always integral in translation with the first cable, which actuates the first braking device according to the first actuation direction .

[0017] According to an embodiment of this invention, said connection bush realises an end-of-stroke stop against a second shoulder of the device body that defines the rest position of the float itself, so as to be able to translate with respect to the device body only for a second actuation stroke, in a second actuation direction opposite to said first actuation direction.

[0018] According to an embodiment of this invention, said second shoulder is arranged on the axially opposite side to said elastic means.

[0019] According to an embodiment of this invention, the device body is fluidically connected to a liquid reservoir connected to said hydraulic fluid chamber through a feed hole, wherein, in the rest condition of the actuator device, the feed hole is arranged axially spaced apart by a gasket of the float in the second actuation direction, the distance between the feed hole and the gasket of the float in the rest condition defining an idle stroke of the float, during which the fluid is not put under pressure by the float.

[0020] According to an embodiment of this invention, the gasket of the float is shaped so as to occlude the feed hole after performing a second actuation stroke greater than, or equal to, said idle stroke, in said second actuation direction.

[0021] According to an embodiment of this invention, said liquid reservoir is in one piece with the device body.

[0022] According to an embodiment of this invention, said actuator device is mechanically connected to the actuation lever or pedal by a second cable, and is connected to the device body by means of a rigid connection element, such as a link block.

[0023] In addition, the technical problem of this invention is also solved by a combined rear-front braking system for a motor vehicle comprising an actuator device as described above, and comprising, as a first braking device, a drum brake, mechanically connected to said first cable, and comprising as a second braking device, a disc brake having a disc brake calliper fluidically connected to said hydraulic fluid chamber of the device body.

[0024] According to an embodiment of this invention, said disc brake calliper is provided with an additional and independent manual lever or pedal actuation device.

[0025] According to an embodiment of this invention, said braking system is a combined rear-front braking system, wherein the first mechanically-actuated braking device is at least a drum brake disposed on a rear axle of the motor vehicle and the second hydraulically-actuated braking device is at least a disc brake arranged on the front axle of the motor vehicle.

DESCRIPTION OF THE DRAWINGS

[0026] Further characteristics and advantages of this invention will be more understandable from the following description of its preferred and non-limiting examples of embodiments, in which: [0027] Figures la-lb are a plan view and a side view of different motor vehicles according to an embodiment of this invention;

[0028] Figure 2 is a partial schematic side view of a system comprising an actuator device according to an embodiment of this invention, in a rest configuration;

[0029] Figure 3 is a sectional view of the system of Figure 2, in a rest configuration;

[0030] Figure 4 is a sectional view of the system of Figure 2, in an actuation or braking configuration;

[0031] Figure 5 is a schematic side view of a braking device according to an embodiment of this invention, in a rest configuration, in which the dashed lines represent the same device in braking configuration;

[0032] Figure 6 is a schematic side view of the braking device of Figure 5, in braking configuration,

[0033] Figure 7 is a sectional view of the braking device of Figure 5, in a rest configuration;

[0034] Figure 8 shows a sectional view of the braking device of Figure 6, in braking configuration;

[0035] Figure 9 is a schematic view of a distribution of braking between two separate braking devices operatively connected to the actuator device of this invention;

[0036] Figures 10 to 11 are perspective views of front axles of motor vehicles comprising actuator devices 4 according to possible variants of this invention.

[0037] The elements, or parts of elements, in common between the embodiments described below will be indicated with the same reference numbers.

DETAILED DESCRIPTION

[0038] With reference to the above figures, the reference number 4 globally indicates an actuator device for a combined rear-front braking system for a motor vehicle 8.

[0039] For the purposes of this invention the concept of motor vehicle must be understood in a broad sense, including not only a motorcycle, but also a three-wheeled vehicle and even a motorised quadricycle.

[0040] The actuator device 4 comprises a device body 12 ) that houses and guides a float 14 mechanically connected to a first cable 16 for the mechanical actuation of an associable first braking device 20, wherein the float defines an axial direction X-X.

[0041] The first braking device 20 can for example comprise a drum brake typically comprising actuatable jaws in contact against a drum integral to a wheel hub, in a known manner.

[0042] The actuator device 4 comprises a manual actuation lever or pedal 24, mechanically connected to said device body 12 so as to command the translation, along said axial direction X-X, of a first actuating stroke 26 in a first actuating direction A, and so as to translate the first cable 16 and actuate the first braking device 20.

[0043] Said actuator device 4 can be mechanically connected to the actuation lever or pedal 24 by a second cable 25, and is connected to the device body 12 by means of a rigid connection element 27, such as a link block.

[0044] The device body 12 delimits a hydraulic fluid chamber 28 that houses a float 14 suitable for putting the fluid of said hydraulic fluid chamber 28 under pressure.

[0045] The hydraulic fluid chamber 28 is fluidically connectable, via an output 36, to an associable second hydraulically-actuated braking device 40, separate from the first braking device 20.

[0046] For example, the second braking device 40 comprises a hydraulically-actuated disc brake calliper.

[0047] For the purposes of this invention the type of disc brake calliper is not relevant, comprising callipers of the fixed or floating type, or further configurations.

[0048] Said disc brake calliper 40 can be provided with an additional and independent manual lever or pedal actuation device 42.

[0049] Between the float 14 and the device body 12 are interposed elastic means 44 so as to actuate the float 14 and put the hydraulic fluid chamber 28 under pressure as a result of the actuation of the actuating rod 16 by means of the manual actuation lever or pedal 24. The float 14 and the first cable 16 are parallel and in series along said axial direction X-X.

[0050] As seen, the device body 12 drags in translation, along the axial direction X-X, the first cable 16 in the first actuation direction A.

[0051] Furthermore, the device body 12 delimits a hydraulic fluid chamber 28 that houses the float 14 suitable to put the fluid of said chamber 28 under pressure when translated with respect to the device body 12, in the axial direction X-X, of a second actuation stroke 56, in a second actuation direction B opposite to the first actuation direction A.

[0052] According to an embodiment, the device body 12 comprises elastic means 44 that exert an elastic thrust on the float 14 in the first actuation direction A to maintain the device body 12 and the float 14 axially integral with each other, said elastic means 44 opposing the actuation thrust of the actuation lever or pedal 24.

[0053] In particular, according to an embodiment, the float 14 translates with respect to the device body 12 of said second actuation stroke 56 in the second actuation direction B, when the thrust exerted on the device body 12 by means of the actuation lever or pedal 24 exceeds the elastic thrust exerted by the elastic means 44.

[0054] These elastic means are a first calibration of the actuator device 4 since the activation or actuation of the second braking device 40 does not take place until the elastic thrust exerted by the elastic means is exceeded by the thrust exerted on the device body 12 by the user acting on the actuating lever or pedal 24. In other words, by increasing the elastic characteristic and therefore the stiffness of the elastic means 44, it is possible to raise the threshold of intervention of the automatic activation of the second braking device 40 following manual actuation of the first braking device 20, and vice versa.

[0055] According to an embodiment, the elastic means 44 are arranged coaxially to the float 14, between a first shoulder 48 of the device body 12 and a plate 50 integral with the float 14 so as to be preloaded, and to influence the float 14 in a rest condition in which the fluid in the hydraulic fluid chamber 28 is not put under pressure by the float 14.

[0056] The float 14 comprises a first connection end 52 to a connection bush 53 of the first cable 16 so as to be always integral in translation with the first cable 16, which actuates the first braking device 20 according to the first actuation direction A. [0057] Said connection bush 53 realises an end-of-stroke stop against a second shoulder 54 of the device body 12 that defines the rest position of the float 14 itself, so as to be able to translate with respect to the device body 12 only for a second actuation stroke 56, in a second actuation direction B opposite to said first actuation direction A. In other words, the second shoulder 54 defines the maximum translation of the float 14 with respect to the device body 12, in the first actuation direction A.

[0058] Preferably, said second shoulder 54 is arranged on the axially opposite side to said elastic means 44.

[0059] According to an embodiment, the device body 12 is fluidically connected to a liquid reservoir 57 connected to said hydraulic fluid chamber 28 through a feed hole 60, wherein, in the rest condition of the actuator device 4, the feed hole 60 is arranged axially spaced apart by a gasket 64 of the float 14 in the second actuation direction B, said gasket 64 being disposed on the head of the float 14. For example, it said gasket 64 is a lip gasket .

[0060] The liquid reservoir 57 can also be in one piece with the device body 12. The liquid reservoir is provided with an upper cap 58 and, according to a possible embodiment, a porthole 59 for checking the level of liquid contained in it.

[0061] The distance between the feed hole 60 and the gasket 64 of the float 14 in the rest condition defines an idle stroke 68 of the float 14, during which the feed hole 60 puts in communication the hydraulic fluid chamber 28 and the liquid reservoir 57, and the fluid is not pressurised by the float 14.

[0062] Such idle stroke 68 represents a second calibration of the actuator device since the activation or actuation of the second braking device 40 does not take place until the actuating lever or pedal 24 is actuated so as to translate the float 14 for a second actuation stroke 56 at least equal to said idle stroke 68.

[0063] In particular, the gasket 64 of the float 14 is shaped so as to occlude the feed hole 60 after performing a second actuation stroke 56 greater than, or equal to, said idle stroke 68, in said second actuation direction B.

[0064] Preferably, the braking system is a combined rear- front braking system, wherein the first mechanically- actuated braking device 20 is at least a drum brake disposed on a rear axle 90 of the motor vehicle 8 and the second hydraulically-actuated braking device 40 is at least a disc brake arranged on a front axle 92 of the motor vehicle 8. [0065] Preferably, the actuator device 4 is fixed to a frame 88 of the motorcycle, in a distal position with respect to the handlebar, so as not to interfere with the space available in proximity of the handlebar. In this way it is possible to bring the actuator device close to the second hydraulically-actuated braking device 40 so as to reduce the length of the hydraulic connection between the output 36 of the actuator device 4 and said second hydraulically-actuated braking device 40. Preferably, said actuator device 4 is fixed to the frame 88 in a vertical position, i.e., with the upper cap 58 facing upwards and the porthole 59 facing downwards, i.e., towards the ground.

[0066] It is also possible to provide that the actuator device 4 be fixed to a portion of handlebar 89 of the motorcycle .

[0067] So, "combined rear-front braking system" means that the single actuation of the first braking device 20, preferably disposed on the rear axle 90, also automatically determines the actuation of the second braking device 40 disposed on the front axle 92. It is clear that, for the purposes of this invention, it is also possible to obtain a combined front-rear braking system so that the single actuation of the first braking device 20, disposed on the front axle 92, also automatically determines the actuation of the second braking device 40 disposed on the rear axle 90.

[0068] Now, the operation of an actuator device according to this invention will be described.

[0069] In particular, it starts from the rest condition in which the user is not actuating the first braking device 20, by means of the corresponding manual actuation lever or pedal 24.

[0070] In this condition, the float 14 is in a rest configuration, and therefore the feed hole is not occluded by the float 14 itself, i.e., by its gasket 64 (Figure 3.7); in other words, in this configuration there is fluid connection between the reservoir 57 and the hydraulic fluid chamber 28, for which the latter is not put under pressure by the float 14 itself and does not activate, through the output 36, the second braking device 40. So, a force is exerted on the actuation lever or pedal 24 in order to operate a braking of the vehicle 8.

[0071] This manual action on the actuation lever or pedal 24 determines the displacement of the device body 12 associated to said actuation lever or pedal 24 through the rigid connection element, such as for example the link block 27.

[0072] The displacement of the device body 12 also determines the translation of the float 14 and the first cable 16 in the first actuation direction A of a first actuating stroke 26. This translation of the first cable 16 determines a first braking action by means of the first braking device 20 mechanically connected to this.

[0073] It should be noted that the thrust action exerted by the user on the actuation lever or pedal 24 is discharged on the elastic means 44 that tend to oppose any relative movement between the float 14 and the device body 12.

[0074] Based on the calibration of such elastic means 44, there is therefore a first phase in which the braking action is exerted by means of the first braking device 20 but no braking action is exerted by means of the second braking device 40, until the elastic action of the elastic means 44 is overcome. In other words, in this first phase the float 14, under the action of the elastic means 44, remains in its rest condition.

[0075] When the force exerted by the user on the actuation lever or pedal 24 is such as to overcome the elastic action of the elastic means 44, these are no longer able to ensure the rest position of the float 14, which therefore starts to move from its rest condition and translate with respect to the device body 12 in a second actuation stroke 56 directed in the second actuation direction B. [0076] This second actuation stroke 56 also corresponds a partial compression of the elastic means 44 with respect to the rest configuration (Figure 4.8) .

[0077] The first intervention or automatic actuation calibration of the second braking device 40 is therefore due to the choice of the elastic constant of the elastic means 44. If the device 4 is configured so that in the rest configuration the gasket 64 of the float 14 is flush with the feed hole 60 (i.e., in the absence of the idle stroke 68), then the immediate displacement of the float of the second actuation stroke 56 corresponds to a substantially immediate actuation of the second braking device 40 as a result of putting the fluid in the chamber 24 under pressure. In fact, this putting under pressure only occurs after the feed hole 60 is occluded. In this case the intervention calibration of the actuator device 4 is performed by playing exclusively on the elastic constant and the elastic means 44.

[0078] If instead there is the presence of an idle stroke 68, then the intervention calibration of the second braking device 40 is also performed in the light of a first stroke of the float 14: in other words, the fluid chamber 28 does not go under pressure and therefore does not activate the second braking device until the float follows a second actuation stroke 56 in the second actuation direction B at least equal to said idle stroke 68.

[0079] It should be noted that the plate 50 of the float performs the function of mechanical limiter of the amount of fluid sent that generates a pressure increase in the second hydraulically-actuated braking device, so as to avoid the risk of locking of the corresponding wheel: in fact, when said plate 50 abuts against the first shoulder 48 of the device body, it prevents the related stroke of the float 14 with respect to the hydraulic fluid chamber 28, i.e., it locks the second actuation stroke and therefore prevents the further increase of pressure in the hydraulic fluid chamber 28.

[0080] A possible actuation scheme of the braking device by means of the actuator device 4 of this invention is, for example, illustrated in Figure 9.

[0081] In particular, the abscissa shows the braking force exerted by the second hydraulically-actuated braking device 40 and the ordinate shows the braking force exerted by the first mechanically-actuated braking device 20. In a first section of the curve marked with "A", note that, thanks to the effect of the elastic means, initially the braking is not combined since it is performed only by the first braking device 20. Then, after overcoming the force exerted by the elastic means 44, braking begins to be exerted also by the second hydraulically-actuated braking device 40 (see section B of the curve) . Finally, the system is calibrated to limit the maximum braking exercisable by the second hydraulically-actuated braking device 40, as seen in section C of the curve. This limitation is achieved by reaching the stop between the plate 50 of the float 14 and the first shoulder 48 of the device body 12; this stop prevents a relative motion in the second actuation direction B between the float 14 and the device body 12 and thus prevents the increase of pressure inside the hydraulic fluid chamber 28.

[0082] As can be seen from Figures 10 and 11, the mounting of the actuator device 4 on the frame of the motor vehicle 8 can be reversed: in other words, it is possible to mount the actuator device 4 either having the second cable 25 connected mechanically to the link block 27 and the first cable 16 connected to the first braking device 20 by means of the connection bush 53 (Figure 10), or having the second cable 25 connected mechanically to the connection bush 53 and the first cable 16 connected to the first braking device 20 by means of the link block 27 (Figure 11) . The two cited solutions are mechanically equivalent to each other and likewise protected by this invention. [0083] As can be appreciated from the description, the actuator device for a combined rear-front braking system for a motor vehicle according to the invention allows overcoming the drawbacks presented in the prior art.

[0084] In fact, the actuator device allows manual actuation, by the user, of the mechanical braking device for example on a rear wheel or axle and, as a function of its calibration, also automatically actuating the hydraulic braking device disposed, for example, on the front wheel or axle.

[0085] The actuator device of this invention is simple and inexpensive to produce and can easily be inserted into a pre-existing non-combined brake system, i.e., with separate and independent actuation of the various braking devices, so as to make it become a combined type system, preferably from the rear towards the front, increasing the effectiveness of the braking system itself.

[0086] This solution is less intrusive on the vehicle layout and, as seen, feasible even on vehicles already present on the market.

[0087] The intervention of the combined braking can be easily calibrated not only as a function of the type of vehicle but also of its load, by acting, as seen, on the calibration, i.e., on the preload of the spring.

[0088] In this way it is also possible to customise and calibrate the intervention of combined braking as a function of the user's taste but also of the effective load conditions of the vehicle.

[0089] The braking system thus configured is always safe and reliable since, in case of failure of the actuator described, the operation of the individual braking devices is not affected but, at most, automatic combined braking is not achieved.

[0090] Advantageously, this invention is also applicable to vehicles with cable command on the handlebar and with little availability of space on the handlebar, such as for example scooters.

[0091] Finally, a mechanical limiter is provided of the output pressure to the second hydraulically-actuated braking device so as to avoid the risk of locking of the corresponding wheel.

[0092] A person skilled in the art, in order to satisfy contingent and specific needs, may make numerous modifications and variations to the actuator devices, to the combined rear-front braking system for a motor vehicle and the related motor vehicle described above, all however contained within the scope of the invention as defined by the following claims.