Disposable or limited use anti-slip system

Abstract

Disclosed herein is an anti-slip system (1; 100) of a motor vehicle, the anti-slip system comprising at least a first and a second injector (2, 4) configured to inject liquid towards the ground (G) at a position in front of a right tread (RT) and a left tread (LT) of a right wheel (R) and a left wheel (L) of an axle of the motor vehicle, respectively, the method comprising:-acquiring a position representative of an intervention event of the anti-slip system (1; the method comprises the steps of:-identifying a signal indicating the need for intervention of the vehicle (10, 100) during a slip event,-identifying a plurality of risk factors (V, Tr, Tc, 0, LC, OA, OV, DR, R, TW) relating to the likelihood of a collision occurring after the vehicle is out of control during the slip event,-acquiring a signal representative of each risk factor from an in-vehicle data network,-defining a collision risk indicator (CR) based on a combination of the signals representative of each risk factor,-determining the risk indicator (CR) based on the defined collision risk indicator (CR). Determining a value of the risk indicator (CR), if the value of the risk indicator (CR) is above a threshold, confirming that intervention of the anti-slip system is required, and controlling the intervention.

Description

Technical Field

[0001] This invention relates to an anti-skid system for motor vehicles. Specifically, the invention is developed with reference to an anti-skid system based on spraying liquid at the front position of the tire tread. Background Technology

[0002] The applicant has developed and proposed an anti-skid system for vehicles, which is based on spraying liquid in front of the tread of the front wheels of a motor vehicle, the liquid being drawn from a windshield washer fluid reservoir. An example of such a system is described in Italian Industrial Invention Patent Application No. 102014902296915.

[0003] Subsequently, the applicant developed methods for determining the interface conditions between the tire and the ground, particularly methods for determining the occurrence of a skidding event, as described in patent applications 102021000017588 and 102022000021216.

[0004] All research conducted by the applicant, and research in general in this field, is based on the assumption of the availability of anti-slip systems with liquid jets that draw liquid from a tank that has essentially unlimited availability relative to the frequency of intervention events. In other words, the deductive logic leading to the determination of the need for intervention events—whether developed by the applicant or possibly implemented on known third-party systems—never considers the possible limited usage patterns of the liquid available for the anti-slip system.

[0005] It should be noted that limited use is not a necessity in itself. Rather, limited use stems from the goal of minimizing the anti-skid system's functional dependence on equipment mounted on the vehicle, such as, for example, windshield washer fluid containers (which are typically the tanks from which the system draws fluid for spraying). Furthermore, limited use allows for the avoidance of installing pumps for the fluids used in anti-skid systems mounted on vehicles.

[0006] By reducing or eliminating dependence, the anti-skid system can be implemented as a fully self-contained unit (a "plug-and-play" unit), while reducing its complexity, cost (due to the absence of a pump), hindrance, and potential difficulties in integrating it into manufactured vehicles (e.g., avoiding the need for separate containers for windshield washer fluid).

[0007] However, as mentioned above, known solutions operate without considering possible limited use and therefore control intervention in the energy storage system solely based on determinations of the vehicle's driving conditions. This inevitably leads to a large number of intervention events that are far too many compared to the actual safety requirements of the vehicle in operation.

[0008] Purpose of the invention

[0009] The present invention aims to solve the above-mentioned technical problems. The present invention aims to provide a disposable or limited-use anti-skid system with a simple structure, easy integration and installation on vehicles, and easy recovery. Summary of the Invention

[0010] The object of the present invention is achieved by means of a method having the features set forth in the appended claims, which form part of the technical disclosure provided herein in relation to the present invention. Attached Figure Description

[0011] The invention will now be described with reference to the accompanying drawings, which are provided by way of non-limiting example only, and in which:

[0012] - Figure 1 This is a schematic diagram of an anti-slip system according to a first embodiment of the present invention.

[0013] - Figure 2 and Figure 3 yes Figure 1 The representation of the operational configuration of the system's components, and Figure 4 Corresponding to along Figure 3 A sectional view of line IV-IV, and

[0014] - Figure 5 This is a schematic diagram of an anti-slip system according to a second embodiment of the present invention. Detailed Implementation

[0015] Figure 1 Reference numeral 1 in the figures generally indicates an anti-skid system for a motor vehicle according to a first embodiment of the present invention.

[0016] System 1 includes at least a first injector 2 and a second injector 4, which are configured to spray liquid toward the ground G from positions in front of the left tire tread LT and right tire tread RT of the left wheel L and right wheel R of a motor vehicle axle, respectively. Furthermore, system 1 includes at least one fluid accumulator 6, which is configured to store pressurized liquid (preferably water) and is in fluid communication with the first injector 2 and the second injector 4.

[0017] refer to Figure 1In a preferred embodiment, system 1 includes a single accumulator 6 in fluid communication with two injectors 2, 4. Fluid communication is implemented via a tee connector 8, which includes two outlets 10, 12 toward the injectors 2 and an inlet 14 from the accumulator 6. Of course, embodiments with one accumulator for each injector 2, 4 are possible. According to the invention, each accumulator 6 includes a refill port configured to restore the liquid volume within the accumulator. In embodiments contemplated according to the invention, the refill ports are configured in different ways.

[0018] System 1 includes at least one flow control element, which includes a first operating condition and a second operating condition. Under the first operating condition, the flow control element is configured to enable liquid flow in the fluid communication between the fluid accumulator 6 and the injectors 2 and 4 when intervention of the anti-slip system 1 occurs (including liquid injection via injectors 2 and 4). Under the second operating condition, the flow control element is configured to disable liquid flow in the fluid communication between the fluid accumulator 6 and the injectors 2 and 4 when intervention of the anti-slip system is not required. In the case of a single accumulator 6, a single flow control element at inlet 14 is conceivable, but preferably, a first flow control element 16 and a second flow control element 18 are operatively associated with the injectors 2 and 4, respectively. This association may include only functional integration with the corresponding injectors 2 and 4, or both functional and structural integration. Preferably, the flow control elements 16 and 18 are implemented as bidirectional, two-position (open / closed) electrically actuated valves.

[0019] The electric actuation of valves 16 and 18 is achieved by means of an (electronic) control unit CU, which is configured to activate a first operating condition and a second operating condition for at least one flow element based on the need for intervention in the anti-slip system. The unit CU sends output (drive) signals S16 and S18 to valves 16 and 18, and simultaneously receives a signal AS corresponding to the activation signal of intervention in system 1.

[0020] exist Figure 1 In the embodiments, and generally in the first embodiment of the invention, the inlet 14 is implemented by means of a series connection of a refill valve 20 and a sensing hydraulic connection port 22, preferably having a quick-release coupling to a connector 8 on which the valve 20 is fixed and on which a pressure sensor 24 is mounted, the pressure sensor being configured to detect the pressure of the liquid at the inlet 14, and thus the pressure of the liquid at the outlets 10, 12. In this respect, reference numeral S24 indicates an operational connection—specifically, a signal connection—between the sensor 24 and the unit CU (the signal S24 is input to the unit CU).

[0021] At a practical level, the refill port includes the components of valve 20 and connection port 22, although from a functional point of view, the liquid enters the accumulator 6 through valve 22, as will be described below.

[0022] In other words, in this embodiment, the refill port includes a hydraulic connection port—located on valve 20—through which a fluid connection is established between (each) accumulator 6 and injectors 10, 12 (which are associated with the number of accumulators 6).

[0023] refer to Figure 2 and Figure 3 Valve 20 includes a housing 26 extending along valve axis X22 and a valve seat V26 at its first end. In this regard, it should be noted that the presence of connection port 22 is not strictly mandatory, as the quick-release coupling at connector 8 and the arrangement of pressure sensor 24 can be easily implemented directly on housing 26.

[0024] Valve 20 also includes a plug 28 movable within housing 26 along valve axis X22. Plug 28 is held in contact with valve seat V26 by means of an elastic element 30 disposed between a shoulder 32 of plug 28 and a shoulder 34 of housing 26, the shoulder 34 being located at a second end of housing 26 opposite to the first end.

[0025] A through-hole 36 is provided at the valve seat V26, establishing fluid communication (through connection port 22) between the interior of the housing 26 and the connector 8. In this way, the refill port is structurally implemented on the connection port 22, but functionally implemented at the valve seat V26. Specifically, the hole 36 directs liquid toward the valve seat V26, through which liquid can enter the accumulator 6. If the connection port 22 is not provided, the refill port is actually implemented structurally and functionally on the housing 26.

[0026] The contact between the plug 28 and the valve seat V26 can be separated by the pressure action of the plug's influence surface S28 against the valve seat V26, wherein the pressure action can be applied by pressing liquid onto the refill port 36.

[0027] Valve 20 also includes a plug actuation element, indicated by reference numeral 38, which is configured to separate the contact between plug 28 and valve seat V26, regardless of whether there is pressure action on the plug's influence surface S28 at valve seat V26.

[0028] Valve 20 includes operating conditions and refill conditions. Under operating conditions, valve 20 is configured to enable the flow of liquid leaving accumulator 6. Under refill conditions, valve 20 is configured to enable the flow of liquid into accumulator 6 and disable the flow of liquid leaving accumulator 6. Actuating element 38 is used to hold valve 20 under operating conditions, while actuating element 38 is substantially deactivated when valve 20 needs to operate under refill conditions.

[0029] More specifically, the actuating element of the plug 38 includes a pin 40 whose axis Y40 intersects (preferably orthogonal to) the valve axis X26. The pin 40 further includes a first operating position and a second operating position, the first operating position defining a first protrusion P1 within the housing 26, and the second operating position defining a second protrusion P2 within the housing 26, the second protrusion being larger than the first protrusion P1. Protrusions P1 and P2 are measured between the inner wall of the housing 26 and the tip of the actuating element 38, which can be identified as the (preferably conical) free end 40T of the pin 40.

[0030] The transition from protrusion P1 to protrusion P2, and vice versa, is preferably achieved by providing threads for pin 40 on the outer surface, and by engaging the threads with corresponding (internal) threads in the wall thickness of housing 26 and / or corresponding (internal) threads on a threaded collar 42 fixed to the outer surface of housing 26. Preferably, actuation of the actuating element 38 is carried out by means of an actuating wheel 44, which is rotatably connected to pin 40.

[0031] The plug 28 includes a tongue 46 configured to contact a valve seat, and a shoulder 48 adjacent to—preferably integral with—the tongue 46, the shoulder 48 including a surface 50 that tapers toward the valve seat V28. The resilient element 30 is thus located between the shoulder 50—which thus acts as a shoulder 32—and the shoulder 34.

[0032] Furthermore, the shoulder 48 includes a guide surface 52 configured to guide the plug 28 during movement along the valve axis X26, particularly providing guidance along the inner wall of the housing 26. The guide surface 52 has a cylindrical shape in the same manner as the inner wall of the housing 26, while the surfaces of the tongue 46 and the valve seat 28 that come into contact with each other are conical.

[0033] To ensure operability under both operating and refilling conditions, the shoulder 48 is slotted by a through-slot 54, which marks a liquid passage between the shoulder 48 and the housing 26, and particularly between the guide surface 52 and the housing 26. Figure 4 A cross-section is shown, revealing the outline of groove 54, which provides—in Figure 4 In the configuration, the shoulder 48 has a roughly cross-shaped shape, at both the guide surface 52 and the gradually tapering surface 50.

[0034] exist Figure 2 In the second (operating) operating position of the visible actuating element 38, the tip 40T of the actuating element contacts the tapering surface 50 of the plug 28, thereby determining the separation of the contact between the plug 28 and the valve seat V26 by means of the second (positive) protrusion P2. In other words, the contact and force exchange between the surface 50 and the tip 40T guides the plug 28 to a new axial position—separated from the seat V26—where the protrusion P2 can be accommodated without interpenetrating between the rod 40 and the surface 50. In this respect, the contact preferably occurs in the area without the groove 54. Under such conditions, the volume of pressurized liquid in the accumulator 6 is always in fluid communication with the connector 8 up to the upstream of the valves 16, 18. Therefore, the sensor 24 detects the pressure of the liquid in the accumulator 6. After the valves 16, 18 are opened by means of the signals S16, S18 provided by the unit CU upon receiving the activation signal AS, the flow of liquid from the accumulator 6 toward the injectors 2, 4 is thus fully enabled.

[0035] On the contrary, Figure 3 In the first (refill) operating position of the visible actuating element 38, the first protrusion P1 (negative in this case) is insufficient to establish separation of the contact between the plug 28 and the valve seat V26. This means that in the first operating position, the protrusion P1 is insufficient to establish contact between the end 40T and the gradually decreasing surface 50, or the contact state (without interpenetration) is compatible with the position of the plug 28, whereby the tongue 46 contacts the valve seat V26. Under these conditions, the seal of the plug 28 against the seat V26 prevents the flow of liquid from the accumulator 6 toward the connector 8. However, the connection of the valve 20—at the orifice 36—to the supply of pressurized liquid acts on the influencing surface S28, thereby separating the contact of the plug 28 against the valve seat V26 and enabling refilling of the accumulator 6.

[0036] Figures 1 to 4 System 1 in the embodiments essentially corresponds to an anti-slip system with a limited volume of liquid, which is replaceable and (refill port) isolated from any fluid circuit of the vehicle, and is configured for single use—or up to two uses depending on the accumulator volume and the gas filling pressure—when intervention of System 1 occurs.

[0037] Due to the rapid-release hydraulic connection between the sensing hydraulic connection port 22 and the valve 20 at the refill port defined by the orifice 36 and the valve seat V26, the refilling of the liquid volume (in this case, corresponding to the replacement of the accumulator 6, as if it were a box of consumable materials) is possible.

[0038] At the operational level, System 1 can be installed on the vehicle during manufacturing because it does not require integration with other systems in the vehicle, except for prior preparation for housing the unit CU and data access on the CAN network.

[0039] Each accumulator 6 is filled with liquid at a pressure of approximately 150 bar and pressurized gas (preferably nitrogen) through port 6R. The gas filling pressure is approximately 60 bar. However, the gas filling pressure can vary depending on the size and / or volume of the accumulator.

[0040] At the operational level, at the vehicle manufacturing site and / or at the system 1 manufacturing site, gas filling is performed via port 6R using pressurized nitrogen cylinders typically available on the market. Subsequently, the necessary amount of liquid is filled (which varies depending on the overall performance of the envisioned system and the number of permissible uses), which for average applications may include between 1.3 liters and approximately 2 liters.

[0041] The liquid is filled by means of a high-pressure pump through a... Figure 3 The flow is initiated by valve 20, which operates as a one-way valve: the contact between the pressure-separating plug 28 and valve seat V26 allows the liquid to flow toward the cavity of accumulator 6. Furthermore, flow is facilitated by groove 54, which substantially bridges the gap between surface 52 and the inner surface of housing 26. Filling is performed with connection port 22 to valve 20, as it provides a quick-release hydraulic coupling to both connector 8 and refill device.

[0042] Once the accumulator 6 is fully filled, remove the accumulator 6 from the refilling device by disconnecting the connection port 22 (or disconnecting the valve 22 if there is no connection port 22), while keeping the valve 20 in the refilling position. In this case, the pressure of the liquid in the accumulator restores the contact between the plug 28 and the seat V26, thereby preventing liquid leakage.

[0043] Next, the accumulator 6 is again installed into the system 1 mounted on the vehicle via the quick-release coupling provided by the connection port 22, with valve 20 always held in the refill position. Once valves 16 and 18 are determined to be in the closed position, valve 20 can be put into the operating configuration by actuating the operating element 38. Figure 2 ).

[0044] In the operating position, plug 28 remains separated from valve seat V26, and therefore nothing except valves 16 and 18 prevents liquid from being discharged from accumulator 6. Liquid can only flow forward and be sprayed toward the ground by ejectors 16 and 18 when unit CU sends signals S16 and S18 to open control valves 16 and 18.

[0045] In any case, monitoring and safety systems can be provided to ensure that the described operation is consistent with the status of various valves and to avoid potentially dangerous actions.

[0046] Once the filling and installation operations are complete, the vehicle is ready for delivery. It should be noted that the depleted accumulator 6 can be immediately replaced with a full accumulator that is already available at the refilling unit, and the removed depleted accumulator 6 can subsequently be refilled and sent to the full accumulator warehouse at the refilling unit.

[0047] refer to Figure 5 Reference numeral 100 generally indicates an anti-slip system according to a second embodiment of the present invention. The same reference numerals as previously used indicate the same parts, while only different reference numerals (plus 100) indicate parts modified relative to system 1.

[0048] From a structural and circuit perspective, system 100 and system 1 are identical; the only difference relates to the inlet of connector 8, indicated herein by reference numeral 114. In this embodiment, channel 114 is a single hydraulic element that forms part of the fluid communication between accumulator 6 and injectors 2, 4, and includes a refill port 136—preferably provided with a quick-release hydraulic connection—corresponding to a branched hydraulic connection port relative to the fluid communication between accumulator 6 (or each accumulator if more than one exists) and injectors 2, 4. A one-way valve 138 (replacing valve 20) is arranged at port 136, configured to allow liquid to enter only toward accumulator 6. Furthermore, a pressure sensor 124 is arranged on channel 114 and is operatively connected to unit CU.

[0049] Unlike System 1, System 100 is always of the single-activation type (possibly with a dual-activation option if the remaining liquid conditions permit), but the liquid is refilled without removing the accumulator 6 and by means of port 136, which can be accessed by a fixed refilling device present in the service workstation.

[0050] More specifically, in system 100, the refill operation envisions connecting port 136, accessible from the engine compartment, to an external refill device and activating it until the liquid fill pressure is reached (during accumulator production, the gas is pre-filled at the manufacturing site). Once refilling is complete, the liquid pressure in system 100 is checked using sensor 124 and access to the unit CU. If necessary, the unit CU is reset, and system 1 is ready for another activation. The latter two operations can be automated using information from pressure sensor 124. At the end of such an operation, the stationary refill device is disconnected from port 136.

[0051] Similar to known anti-slip systems, systems 1 and 100 operate based on activation signals generated by electronic systems for detecting slip conditions (such as those described in patent applications 102021000017588 and 102022000021216 mentioned at the beginning of this specification) using a unit CU as an interface.

[0052] According to the invention, due to the limited use of fluid in systems 1, 100—because it is isolated from the vehicle's fluid circuitry—the determination of the activation signal AS utilizes a further layer of inference, which benefits from integration with driving assistance systems (ADAS) to identify truly dangerous skidding conditions by incorporating the risk factors provided. Considering the reduced availability of fluid for intervention, this results in a minimum number of intervention events for systems 1, 100 from a safety perspective.

[0053] More specifically, studies on the performance of anti-skid systems during normal vehicle use have demonstrated the importance of considering risk factors related to the conditions in the surrounding area where a skid event may occur.

[0054] Given that the vehicle is in a state of initial or actual loss of control (due to a skidding event), the risk of an actual collision resulting from this loss of grip depends on several factors that are not strictly related to the skidding event itself.

[0055] Table 1 below summarizes some of the factors mentioned:

[0056]

[0057] Most of these factors are evaluated (or can be evaluated) by the vehicle's ADAS system and converted (or can be converted) into signals available on the vehicle's CAN network, as shown in Table 2 below:

[0058]

[0059] Then, a global assessment of the level of collision risk due to loss of grip in a given situation is performed by combining all the risk factors that exist at the same time, for example by assigning weights to each of them (which can be fixed or associated with each level of other parameters).

[0060] Therefore, the collision risk indicator CR can be defined as a weighted linear combination of signals obtained from the CAN network: Where a, b, c, d, e, f, g, h, i, l represent the weight parameters (except for one of them, i.e., the one they are multiplied together) that are functions of various risk factors.

[0061] Generally, each weight parameter a, b, c, d, e, f, g, h, i, l is a function representing at least one of the signals obtained from the CAN network for each risk factor.

[0062] Essentially, the collision risk indicator CR represents a weighted sum of various risk factors, where the weight of each factor can be a function of the other risk factors. When an algorithm implemented on the vehicle for detecting skid conditions (regardless of its type, and not necessarily as described in patent applications 102021000017588 and 102022000021216 mentioned at the beginning of this specification—although they represent preferred solutions) determines the intervention status of system 1, 100, the actual activation of the system (i.e., signal AS) depends on further checks based on the indicator CR. In other words, the activation of the anti-skid system is always regulated by the indicator CR.

[0063] More precisely, the present invention envisions that if the value of the indicator CR is higher than a threshold level considered critical in terms of safety, then intervention in System 1, 100 is enabled—but this can be extended to any known anti-slip system based on liquid jetting, even if its usage is unrestricted. In other words, if the slip condition is confirmed and (logically AND) if the value of CR is higher than the threshold, then the anti-slip system is activated using the associated intervention request.

[0064] To illustrate this activation logic, suppose a vehicle is traveling in a straight line (Tr - low level) at 110 km / h on a highway in rainy conditions. Suppose the vehicle encounters a flooded area to determine the risk of skidding. If the vehicle continues at a constant speed (V - medium risk), if the driver does not request a change of trajectory (LC=0, DR=0), if there are no other vehicles nearby (OV=0), if there are no obstacles in the trajectory (O=0), if the road surface is flat (OA=0), and if the road is straight and very wide (and in this case, R=0, TW=0), then—especially if all the preceding conditions are true simultaneously—the actual risk is very low, even though the algorithm used to detect skidding indicates a lack of control, and is insufficient on its own to determine whether the anti-skid system needs to be activated. This corresponds to the collision risk indicator CR being below a threshold.

[0065] Conversely, if the vehicle is under the same conditions as before, but encounters water accumulation in the track that is asymmetrically distributed relative to the vehicle's axis (water accumulation only on one side of the vehicle), the result is a yaw moment on the vehicle (which may or may not be offset by the driver's reaction) or a lack of uniform grip. The risk factors DR and OA increase to a point that may exceed the threshold of CR, and this can determine the need for intervention from the anti-skid system, which then delivers a liquid jet to restore the vehicle's attitude and prevent spin.

[0066] It should be noted that, due to the inherent characteristics of these factors, the aforementioned set of risk factors is well-suited for obtaining an estimate of collision risk based on a simplified restatement of risk factors Tc (bending trajectory) and O (obstacle). These two risk factors, which can also be inferred from the representation signals available on the CAN network, effectively encompass most of the other listed risk factors, and therefore can be used as a primary reference for calculations. For example, just as risk factor O includes at least risk factors OV, TW, and R, risk factor Tc includes at least risk factors V, LC, OA, DR, and R.

[0067] As a result, in a preferred embodiment, operation can be based on a standard that classifies risk factors into risk factors caused by the trajectory (TR) of a vehicle and risk factors caused by potential obstacles (e.g., vehicles, objects, people, etc.) present on the trajectory (CT).

[0068] Therefore, in such an embodiment, a decision sequence with the following characteristics is implemented.

[0069] In the first step, the actual / current grip coefficient is determined: Based on the digital systems mounted on the vehicle and / or on additional sensors (such as cameras or LiDAR) connected to autonomous driving functions, the vehicle's grip coefficient can be determined. Specifically, it can be determined whether a partial or complete slippage event is occurring, and the coefficients of friction associated with the rear and front axles and their changes due to slippage can be determined.

[0070] In the second step, the vehicle's trajectory (TR) and surrounding environment (CT) are determined.

[0071] When the vehicle is in motion, it should always meet two criteria based on the indicators (TR, CT). The first criterion (TR) corresponds to the vehicle's ability to stay within the track (i.e., without leaving the road surface) and follow the desired trajectory. This is verified when the given trajectory is traveled at the correct speed for the current grip coefficient.

[0072] The second standard (CT) corresponds to the need to avoid collisions with other vehicles or, typically, obstacles. In other words, it corresponds to the contact exclusion zone between the vehicle and surrounding objects (including other vehicles). As for driving, the vehicle's speed and position are adjusted based on a safe distance that takes into account the coefficient of traction and the driver's reaction time. If the safety factor decreases, the safe distance should be increased.

[0073] The vehicle's trajectory and surrounding environment can be calculated using the same systems used for autonomous driving, which should always adhere to the two criteria mentioned above. For example, cameras can be used to detect the presence of other vehicles or obstacles, or to define the trajectory the vehicle should follow to stay on the road. Distance sensors can help determine the space between the vehicle and the vehicle in front. The trajectory requested by the driver can also be determined using data from sensors at the steering angle (e.g., the angle of the steering wheel), accelerator pedal, and brakes.

[0074] In the third step, it is determined whether the trajectory and surrounding area are correct for the current grip coefficient. This step also considers elements of vehicle dynamics, which can be arbitrarily complex to increase the level of detail in the mathematical modeling. For clarity, consider the following simplification based on three equations: in: Fx is the resultant force of longitudinal forces on the vehicle. Fy is the resultant force of the lateral forces on the vehicle. μx is the vehicle's longitudinal grip coefficient. μy is the vehicle's lateral grip coefficient. g is the acceleration due to gravity. m is the mass of the vehicle Ax is the longitudinal acceleration of the vehicle. Ay is the lateral acceleration of the vehicle.

[0075] In addition, an equation can be written that is based on the exclusion region (CT) and on the fact that... The total grip coefficient μ, calculated from the square root of μ, is used to define the narrowest path (i.e., the path with the minimum radius of curvature R) that a vehicle can travel on.

[0076] Once the current coefficient of friction has been calculated as defined in the first step (so the grip coefficients μx, μy, and μ are known), the maximum acceleration that the vehicle can withstand based on the friction with the ground is known.

[0077] In the second step, the surrounding area CT and the trajectory TR that the vehicle will face are calculated. From these values, the longitudinal acceleration Ax(TR, CT) and the lateral acceleration Ay(TR, CT) that the vehicle should comply with can be defined in order to follow the trajectory TR and comply with the surrounding area CT.

[0078] If two conditions μ > Ax(TR, CT) / g AND μ > Ay(TR, CT) / g are satisfied simultaneously, it is determined that no action needs to be taken, so the intervention of the anti-slip system is not defined.

[0079] In fact, under these conditions, the grip coefficient is higher than any other action taken by the vehicle.

[0080] If at least one of the conditions μ < Ax(TR, CT) / g and μ < Ay(TR, CT) / g is satisfied (logical OR), the current grip coefficient is not sufficient to cope with the actions that the vehicle may take, and thus is not sufficient to assist possible emergency trajectories / braking. Therefore, corrective actions are taken, which can include, for example, the activation of the anti-slip systems 1, 100.

[0081] The fourth step corresponds to the definition of corrective actions. Once it is found that the available grip is not sufficient to support possible emergency maneuvers or feasible maneuvers performed by the vehicle, further differences are defined to avoid unnecessary activation of the systems 1, 100. For example, consider the case where a vehicle follows another vehicle at a distance that is correct for a total grip coefficient μ = 0.8 (wet asphalt road), and where the sensor network mounted on the vehicle detects the said value of the grip coefficient.

[0082] If the vehicle maintains the same safety distance from the vehicle in front, this means a possible risk because the vehicle in front may need to brake, and thus due to the reduction of the friction coefficient, the rear vehicle will be too close to avoid a collision. On the contrary, if the vehicle in front does not brake, but moves forward at a constant speed or even accelerates, the rear vehicle is not in an immediate and imminent dangerous situation. In this case, one possibility is to use the moment when the vehicle in front moves forward at a constant speed to decelerate the rear vehicle and create safety conditions, thereby increasing the grip coefficient.

[0083] On the other hand, if the vehicle in front brakes, the current grip coefficient may not be sufficient to avoid a collision. In this case, in order to help avoid a collision, it is useful to increase the grip coefficient during braking. The analysis provided above can be performed separately for the longitudinal and lateral movements of the vehicle, or for movements with a mixed longitudinal and lateral composition.

[0084] This situation poses a potential hazard when the vehicle in front brakes. In other situations—when the vehicle in front is moving at a constant speed or accelerating—this situation poses an actual hazard, and it is usually associated with the activation of the anti-skid system 1, 100.

[0085] To minimize system activation and consumption, it is preferable to operate in the following manner.

[0086] In potentially dangerous situations, as long as the activation of the anti-skid system does not appear absolutely necessary, action can be taken by means of the autonomous driving system or by issuing a warning to the driver, so that the vehicle can slow down and return to safe conditions.

[0087] In actual hazardous situations, when such intervention can actually improve the grip coefficient μ and thus help the vehicle avoid a collision with the vehicle in front (or usually with an obstacle), the anti-skid system 1, 100 is activated. It should be noted that potentially hazardous situations and actually hazardous situations correspond to the collision risk indicator CR, or more precisely, situations below the intervention threshold (potentially hazardous) and situations above the intervention threshold (actually hazardous).

[0088] If the detection logic for a slip condition (whatever it may be) determines that such a condition has occurred, then the activation of the liquid jet depends on further checks for the presence of an actual hazard. If an actual hazard is detected, the anti-slip system is activated in the manner described.

[0089] Generally, the present invention therefore defines a method for managing intervention events of an anti-skid system 1, 100 of a vehicle, the anti-skid system including at least a first injector 2 and a second injector 4, the first injector and the second injector 2, 4 being configured to spray liquid toward the ground G at positions respectively in front of the right tread RT and left tread LT of the right wheel R and the left wheel L of the vehicle axle, the method comprising:

[0090] - Obtain signals indicating the need for intervention in anti-slip systems 1 and 100.

[0091] - Identify multiple risk factors associated with the likelihood of a collision following loss of vehicle control during a skidding event: V, Tr, Tc, O, LC, OA, OV, DR, R, TW (see Table 1).

[0092] - Obtain signals representing each risk factor from the vehicle data network (e.g., CAN network) (see Table 2 - in the example described above, such signals include, i.e., accelerations Ax and Ay).

[0093] - Define the collision risk indicator CR based on the combination of signals representing each risk factor, and determine the value of the risk indicator CR (actual or potentially dangerous situation, and / or the position of μ relative to the ratios Ax(TR,CT) / g and Ay(TR,CT) / g).

[0094] - If the risk indicator CR value is higher than the threshold, the need for intervention in anti-slip systems 1 and 100 is confirmed, and the intervention is controlled.

[0095] As described above, the method also includes denying the need for intervention in the anti-slip system and preventing intervention if the value of the risk indicator CR is below the threshold.

[0096] As observed above, this applies not only to anti-skid systems 1 and 100, but also to other known anti-skid systems based on the injection of fluid at the front position of the tread. In the case of systems 1 and 100, this logic maximizes the extension of the interval between refills of accumulator 6, as it activates systems 1 and 100 only when absolutely necessary.

[0097] Based on the duration of the jet and / or the pressure detected by sensors 24, 124, the unit CU may decide whether to allow further use of system 1, 100 (if the remaining pressure is sufficient for a second activation), or to warn the driver by means of a warning light on the dashboard that system 1, 100 should be restored and suggest that it is necessary to reach the work station while adopting a cautious driving style.

[0098] The following process for replacing one or more accumulators 6 at a service station is similar to the process described above regarding the refilling method. It should be noted that the service station may be equipped with accumulators 6 already filled with gas and liquid in such a way that the replacement operation is accelerated and subsequent refilling of accumulators 6 removed from the vehicle is provided to inspect them and make them available for later use on another vehicle.

[0099] In this way, the replacement cost for the customer will not include the full cost of accumulator 6, but only the cost of refilling and inspection operations.

[0100] For anti-slip systems where fluid availability is not an issue, the method according to the invention enables optimization of fluid consumption in any situation, particularly when the latter is shared with other systems in the vehicle, such as, for example, windshield washer systems or cleaning systems for sensors supporting driver assistance systems.

[0101] Of course, without departing from the scope of the invention as defined by the appended claims, the implementation details and embodiments may differ considerably from those described and shown herein.

Claims

1. An anti-skid system (1; 100) for a motor vehicle, comprising: -At least the first injector and the second injector (2, 4) are configured to inject fluid toward the ground (G) at positions in front of the right tire tread (RT) of the right wheel (R) and the left tire tread (LT) of the left wheel (L) of the motor vehicle axle, respectively. At least one accumulator (6) is configured to store fluid under pressure and is in fluid communication (8) with the first injector (2) and the second injector (4). At least one flow control element (16, 18) includes a first operating condition and a second operating condition. Under the first operating condition, the at least one flow control element is configured to enable fluid flow in the fluid communication between the at least one accumulator (6) and the first injector (2) and the second injector (4) when the anti-slip system (1) intervenes, the intervention including ejecting fluid by means of the first injector (2) and the second injector (4). Under the second operating condition, the at least one flow control element is configured to disable fluid flow in the fluid communication between the at least one accumulator (6) and the first injector (2) and the second injector (4) when the anti-slip system (1) does not require intervention. The control unit (CU) is configured to enable the first and second operating conditions of the at least one flow element based on the need (AS) for intervention in the anti-slip system (1; 100). The at least one accumulator includes a refill port (36; 136) configured to restore liquid within the accumulator (6).

2. The anti-slip system (100) according to claim 1, wherein, The refill port (136) includes a hydraulic connection port that is branched relative to the fluid communication (114) between the at least one accumulator and the first injector (2) and the second injector (4).

3. The anti-slip system (1) according to claim 1, wherein, The refill port (136) includes hydraulic connection ports (22, 36) through which fluid communication is formed between the at least one accumulator (6) and the first injector (2) and the second injector (4).

4. The anti-slip system (1) according to claim 4, wherein, The refill port includes a valve (20) which includes operating conditions and refill operating conditions. Under the operating conditions, the valve (20) is configured to enable the flow of fluid leaving the accumulator (6) and under the refill operating conditions, the valve (20) is configured to enable the flow of fluid into the accumulator (6) and disable the flow of fluid leaving the accumulator (6).

5. The anti-slip system (1) according to claim 4, wherein, The valve (20) includes: - A housing (26) extending along the valve axis (X26), the housing (26) including a valve seat (V26) at one end. - A plug (28) movable within the housing (26) along the valve axis (X26), wherein the plug (28) is held in contact with the valve seat (V26) by means of an elastic element (30) disposed between the shoulder (32) of the plug (28) and the shoulder (34) of the housing (26), and wherein the contact between the plug (28) and the valve seat (V26) is separated by pressure acting against the influence surface (S28) of the plug (28) at the valve seat (V26). - The actuating element (38) of the valve plug (28) is configured to disengage the contact between the valve plug (28) and the valve seat (V28), regardless of whether there is pressure acting against the affected surface (S28) of the valve plug (28) at the valve seat (V26). The refill port is located at the valve seat (V26).

6. The anti-slip system (1) according to claim 5, wherein, The actuating element (38) of the valve stem (28) includes a pin (40) having an axis (Y40) that intersects, preferably orthogonal to, the valve axis (X26). The actuating element (38) has a first operating position of a first protrusion (P1) defined within the housing (26) and a second operating position of a second protrusion (P2) defined within the housing (26), the second protrusion (P2) being larger than the first protrusion (P1). In the second operating position, the tip (T40) of the actuating element (38) contacts the surface (50) of the plug that gradually decreases towards the valve seat (V26), and the second protrusion (P2) causes the contact between the plug (28) and the valve seat (V26) to separate. In the first operating position, the first protrusion (P1) is insufficient to determine the separation of the contact between the plug (28) and the valve seat (V26).

7. The anti-slip system (1) according to claim 6, wherein, In the first operating position, the tip (T40) separates from the surface (50) of the plug (28) that gradually decreases toward the valve seat (V26).

8. The anti-slip system (1) according to any one of claims 6 and 7, wherein, The plug (28) includes: - A tongue (46) is configured to contact the valve seat (V26) and includes the affected surface (S28). - A shoulder (48) adjacent to the tongue (46) includes a surface (50) that gradually decreases toward the valve seat (V26), and the shoulder (48) also includes a guide surface (52) configured to guide the plug (28) to move along the valve axis (X26). The elastic element (30) is included between the shoulder (48) and the end (34) of the housing (26) opposite to the valve seat (V26), and The shoulder (48) is slotted by a through groove (54), which marks a liquid passage between the shoulder (48) and the housing (26), particularly between the guide surface (52) and the housing (26).

9. The anti-slip system (1) according to any one of the preceding claims, wherein, The refill port includes a quick-release coupling (22; 136).

10. A vehicle comprising an anti-skid system (1; 100) according to any one of claims 1 to 9, wherein, The refill port is isolated from any fluid circuits of the vehicle.

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