TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates in general to a system for preventing the phenomenon of aquaplaning in a motor-vehicle.

In particular, the invention relates to a pumping unit of a system for preventing the phenomenon of aquaplaning in a motor-vehicle, configured to generate the operating pressure of a jet of fluid directed onto a road surface.

Prior art

As is known, aquaplaning is a phenomenon that may occur when a moving motor-vehicle encounters a layer of water extended on the road surface, in such a quantity as to no longer allow adequate adhesion between the wheels of the vehicle and the road surface. Consequently, in these conditions, a condition occurs of lifting and/or skidding of the wheels on the wet road surface, with consequent loss of grip of the tires.

In order to reduce the risks deriving from this phenomenon, various solutions have already been studied and proposed, including the one described in the Italian patent application No. 102014902296915, by the same Applicant. The solution described in this document envisages the use of injector means, associated with at least one wheel of the motor-vehicle, configured to generate a jet of high pressure fluid onto the wet road surface.

One of the major problems of the known solutions consists in generating adequate flow rate and pressure of the jet of fluid, as well as extremely rapid intervention times, in order to ensure an effective anti-aquaplaning action.

Object of the invention

The object of the invention is to provide a pumping unit of the type indicated above, which guarantees high pressures of the jet of fluid, and particularly rapid intervention times.

Another object of the invention is to create a pumping unit of the type indicated above that is extremely reliable in operation and that does not interfere with other components and systems of the vehicle, when an anti-aquaplaning action is not required.

Another object of the invention is to create a pumping unit of the type indicated above that can be easily installed on-board a motor-vehicle.

Another object of the invention is to provide a pumping unit of the type indicated above that can be easily integrated with other components of the system.

Summary of the invention

According to the present invention, the aforesaid objects are achieved by a system and a relative method for preventing the phenomenon of aquaplaning in a vehicle, having the characteristics forming the subject of the attached claims.

The claims form an integral part of the disclosure provided here in relation to the invention.

Brief description of the drawings

The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein:

- Figure 1 is a schematic perspective view that illustrates a preferred embodiment of the system according to the invention,

- Figure 2 is a schematic view that illustrates the components and the operation of a preferred embodiment of the system according to the invention,

- Figure 3 is an additional schematic perspective view that illustrates different components of the system of Figure 1 ,

- Figures 4A-4C are a perspective view, an exploded perspective view, and a cross-sectional view illustrating a preferred embodiment of a pumping unit according to the present invention, and

- Figures 5-8 are perspective views on an enlarged scale illustrating different components of the pumping unit of Figures 4A-4C.

Detailed description

In the following description, various specific details are illustrated aimed at a thorough understanding of examples of one or more embodiments. The embodiments can be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. The reference to “an embodiment” in the context of this description indicates that a particular configuration, structure or characteristic described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as “in an embodiment”, possibly present in different places of this description do not necessarily refer to the same embodiment. Moreover, particular conformations, structures or characteristics can be combined in a suitable manner in one or more embodiments and/or associated with the embodiments in a different way from that illustrated here, for example, a characteristic here exemplified in relation to a figure may be applied to one or more embodiments exemplified in a different figure.

The references illustrated here are only for convenience and do not therefore delimit the field of protection or the scope of the embodiments.

Figures 1-3 are schematic views illustrating a preferred embodiment of an anti-aquaplaning system S that can be installed on-board a motor-vehicle V, designed to restore the correct contact of the wheels W of the motor-vehicle V on a wet road surface.

Some construction details of the system are not illustrated in the attached drawings, since they can be made according to techniques widely known in the technical field of reference.

The system S comprises at least one fluid reservoir 8 and injector means 9 configured to direct a jet of high pressure fluid onto the wet road surface, so as to remove the layer of water that stagnates on said surface. The injector means 9 are associated with at least one wheel of the motor-vehicle V, preferably in front of the treads of the front wheels W.

According to the present invention, the system S comprises a pumping unit 1 configured to generate the operating pressure of the jet of fluid directed onto the road surface. As illustrated in Figures 1-3, the pumping unit 1 is operatively interposed between the reservoir 8 and the injector means 9.

In the schematic view of Figure 2, which illustrates the main components and the general operation of the system S, the references 30, 31 , 32, 33, 34, 35 indicate a plurality of hydraulic ducts designed to connect the various components, while the references 40, 41 , 42, 43 indicate the logical functional connections between the components of the system S. Preferably, the jet of fluid injected by the injector means 9 is taken from the reservoir of screen-washing fluid of the motor-vehicle V. Reference 8’ indicates an auxiliary reservoir, which houses an auxiliary liquid, preferably a defoaming liquid. A mixing assembly 11 is hydraulically connected to the reservoir 8 and to the auxiliary reservoir 8’.

The fluid supply is ensured by a pumping unit 1 comprising an intake mouth 12 and a delivery mouth 13. Still with reference to the schematic view of Figure 2, it can be observed that the pumping unit 1 comprises an electric motor 5 and a braking device, the operation of which is described in detail below.

Again with reference to Figure 2, the references 14 indicate two non return valves, arranged, respectively, upstream of the intake mouth 12 and downstream of the delivery mouth 13. A respective solenoid valve 16 is arranged upstream of each injector 9, and is configured to selectively enable a transit of fluid, so as to allow the emission of the jet of fluid. The system S further comprises a safety valve 21 arranged to control and limit the pressure of the circuit. As will be illustrated in detail later in the description, the system S also comprises an accumulator 15 designed to keep the entire circuit under pressure, and to prevent having to install a damping spring inside the pumping unit 1 , so as to be able to reduce the weight of the pumping unit 1 and its mechanical complexity.

The system S also comprises an electronic control unit E associated with at least one sensor configured to detect the dynamic conditions of the motor- vehicle V and/or the environment wherein the vehicle V is located (in particular the conditions of the road surface). The control unit E is configured to control the injector means 9 and the electric motor 5, so as to generate a jet of fluid by means of the pumping unit 1 , according to the conditions detected.

Preferably, said at least one sensor comprises at least one sensor already mounted on-board the vehicle V, in order to share the functionalities and to reduce the production costs of the system S according to the present invention.

In particular, said at least one sensor comprises at least one sensor of the following typologies:

- a speed sensor, which allows determining the speed at which the vehicle V is travelling;

- an angular speed sensor, to determine if all the wheels of the vehicle V rotate at the same speed, if a curved path is being followed, or if one or more wheels are accelerating or decelerating without warning;

- a rain sensor, in order to determine if it is raining in the section of street surface S wherein the vehicle V is found;

- an accelerometer and gyroscope, in order to determine any onboard passengers of the vehicle V;

- a water sensor, in order to determine if the wheels of the vehicle V lift a determined amount of water;

- a sensor that determines the steering angle of the vehicle V, which allows it to understand if said vehicle V is proceeding on a straight street surface or not;

- a tilt angle sensor, which allows both the longitudinal and lateral acceleration to be controlled;

- a sensor associated with least one tire of a wheel of the vehicle V, and suitable for activating the system S, exploiting the information coming from said at least one tire.

Safety systems may then be associated with said at least one sensor (for example, of type ABS, ESP and the like), which are usually mounted on-board the vehicle V; these security systems allow the provision of information relative to the speed and acceleration of the vehicle V, the angular velocity and steering for every wheel, the presence of water on the street surface, braking conditions, and so on.

Moreover, said at least one sensor may comprise sensors specifically studied and conceived for the system S, such as, for example, an infrared sensor suitable for verifying the presence of an anomalous layer of water that is about to be reached by the vehicle, and so on.

Figures 4A-4C illustrate a preferred embodiment of a pumping unit 1 , according to the invention. The pumping unit 1 is a volumetric single-cylinder piston pump, configured to generate the operating pressure of the jet of fluid to be directed onto the road surface by means of the injector means 9.

As widely known in the technical field of reference, a high pressure volumetric pump generally comprises at least one piston, slidably housed inside a cylinder, so as to define therewith a variable volume pumping chamber, which communicates with an intake duct and a delivery duct through respective valves. The piston is controlled to alternatively perform an intake stroke, wherein the volume of the relative operating chamber increases by recalling the fluid from the intake valve, and a delivery stroke, wherein it reduces the volume of the operating chamber, forcing the fluid to exit under pressure from the delivery valve.

As illustrated in Figures 4A-4C, the pumping unit 1 comprises a pump body 10, preferably made of steel, within which a pumping chamber defined by a cylinder-piston assembly 2 is formed. The cylinder-piston assembly 2 is spaced along a pumping axis X1 and comprises a cylinder 3 within which a piston 4 is slidably mounted. As previously indicated, the cylinder 3 is connected with an intake pipe 31 and a delivery pipe 32. The piston 4 can be moved forward and backward to vary the useful volume of the cylinder 3 by means of a screw-nut mechanism 22 designed to convert a rotary movement into a linear movement.

Reference 5 indicates an electric motor designed to develop the drive torque required to operate the pumping unit 1. The electric motor 5 comprises a crankshaft 50 operatively connected to the aforesaid screw-nut mechanism 22, according to the characteristics indicated below.

In accordance with a relevant characteristic of the invention, the crankshaft 50 is spaced along a second axis X2 different from the aforesaid pumping axis X1. As shown in Figures 4A, 4C, the electric motor 5 and the pumping chamber are arranged side-by-side with respect to each other, with the axes X1 , X2 parallel to each other. The pumping unit 1 comprises a gear train transmission 6 arranged to transmit the motion from the electric motor 5 to the screw-nut mechanism 22 associated with the piston 4, also guaranteeing the transmission ratio required to reduce the rotation speed from the crankshaft 50 to the screw-nut mechanism 22.

In one or more embodiments, as well as in the one illustrated in the drawings, the transmission comprises a plurality of gear wheels including a driving wheel 60 integral with the crankshaft 50, a driven wheel 62 integral with the piston 4, and at least one intermediate wheel 61 , designed to transmit the rotation motion from the crankshaft 50 to the screw-nut mechanism 22 (Figure 5). The gear train transmission 6 is also arranged to reduce the rotation speed of the motor 5 to a value compatible with the screw-nut mechanism 22. Preferably, the gear ratio is 1/5.

Thanks to the fact that the crankshaft 50 is spaced along a second axis X2 offset with respect to the aforesaid pumping axis X1 and to the interposition of the aforesaid transmission 6, the pumping unit 1 has a relatively limited overall length, allowing easy installation on-board the motor-vehicle V, in particular, in an area of the engine compartment near the front bumper at the height of the headlights.

As indicated above, the pumping unit 1 comprises a screw-nut mechanism 22 designed to convert a rotation movement - transmitted by the crankshaft 50 to the driven wheel 62 - into a linear movement - to be transmitted to the piston 4. In one or more embodiments, as well as in the one illustrated in Figure 4B, the mechanism 22 comprises a rod 19 axially spaced within the piston 4, and operatively connected to the driven wheel 62, so that the wheel 62 rotates the rod 19. The mechanism 22 also comprises a tubular flange 20 fixed to one end 24 of the piston 4, bearing an inner thread engaged with an outer thread (not shown in the drawings) obtained along the outer surface of the rod 19. Therefore, during the operational steps of the pumping unit 1 , the driven wheel 62 drives the rod 19 into rotation, whose rotation causes an axial displacement of the tubular flange 20 and of the piston 4. Note that the mechanism 22 also comprises a set of bearings 18 to reduce the friction resulting from the rotation of the rod 19. Naturally, alternative configurations of the mechanism 22 with respect to what has been described above can be provided, as long as they can function to obtain the aforesaid axial movement of the piston 4.

In one or more embodiments, the piston 4 is made of aluminum alloy, so as to be able to withstand the stresses generated by the operating pressures.

In one or more embodiments, as well as in the one illustrated in Figure 7, the piston 4 has a configuration designed to optimize operation, preventing the piston 4 from rotating with the rod 19. Preferably, the piston 4 comprises a plurality of recesses 25 formed along the body of the piston 4, arranged to lighten the overall weight of the piston 4 and to allow the piston 4 to be tightened with a nut screw.

In one or more embodiments, the piston 4 comprises sealing means arranged to seal the piston 4, ensuring an efficient movement with minimum friction. As illustrated in Figure 7, the sealing means may comprise at least one annular gasket 26 (O-ring) made of elastomeric material, coaxially interposed between the piston skirt and the seat wherein the piston skirt is slidably received. The piston 4 is also shaped to be able to accommodate a plurality of mutually spaced-apart seals along the direction defined by the longitudinal axis of the piston 4. In one or more embodiments, as well as in the one illustrated in Figure 6, the pumping unit 1 comprises two position sensors 23 for detecting the stroke- end positions of the piston 4. The sensors 23 are positioned at opposite ends of the cylinder 3, and are designed to prevent damage to the piston 4 in the event of anomalies relating to position control.

The pumping unit 1 also comprises a braking device 7 associated with the electric motor 5, designed to lock the operation of the pumping unit 1 during a rest condition of the system S, wherein the emission of the jet of fluid is not required. In one or more embodiments, the braking device 7 is an electromagnetic brake comprising a solenoid designed to lock the pumping unit 1 during a rest condition of the system S. The electromagnetic brake comprises spring means capable of pushing a ferromagnetic anchor into a position configured for keeping the piston 4 in a locked position, and an electromagnet designed to magnetically attract the anchor into a position configured for allowing operation. Therefore, in a normal rest condition wherein the emission of the jet of fluid is not required, the braking device 7 produces a braking effect that locks the pumping unit 1. Note that the overall time to unlock the pumping mechanism is approximately 50 ms. It should also be noted that the braking device 7 is capable of keeping the pumping unit 1 under pressure.

In one or more embodiments, as well as in the one illustrated in the drawings, the pumping unit 1 comprises an accumulator 15 arranged to provide a reserve of fluid, regulating delivery and supply pressure of the fluid, so as to keep the hydraulic circuit under pressure, even during a rest condition of the system S, thus reducing the overall intervention time to generate the emission of the jet of fluid. The accumulator 15 is also designed to dampen the reaction forces and to prevent having to install damping springs inside the pumping unit 1 , so as to avoid an increase in weight and complexity of the pumping unit 1.

With reference to Figure 8, the pumping unit 1 comprises a fastening bracket 17 designed to secure the pump body 10 in the engine compartment of a motor-vehicle, preferably made of steel. The fastening bracket 17 is sized to avoid structural anomalies linked to phenomena of local cyclic plastic micro deformations induced by the cycle of stresses.

Thanks to the characteristics described above, the pumping unit 1 is capable of achieving the required flow rate - with the necessary pressure increase - to achieve the required effect. In one or more embodiments, the injection pressure developed is 60 - 150 bars.

As is evident from the foregoing description, the volumetric pumping unit 1 according to the invention is designed to generate adequate pressure and flow rate of a jet of fluid directed onto the road surface in an anti-aquaplaning system. According to the advantageous characteristics described above, the pumping unit 1 is made in such a way as to ensure particularly rapid intervention times and extremely reliable operation, while at the same time being easily installed on board a motor-vehicle.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the invention as defined by the claims that follow.