EP4731455A1 - Control system and method for adjusting air pressure in a vehicle wheel - Google Patents

Abstract

A vehicle wheel (1) has a rim (3), a tire (4) defining, together with the rim, a chamber (5) which is filled with air and can be pressurized, and an assembly (20) for adjusting the air pressure in such chamber (5); the assembly is provided with at least one compressor (21) pneumatically connected to the chamber (5), and with at least one reservoir (22) carried by the rim (3) and pneumatically connected to the compressor (21) to receive compressed air; at least one battery supplies electric power to the compressor (22); the pressure in the chamber (5) is adjusted by causing air to flow between the reservoir (22) and the chamber (5); in case of a temperature increase of the air in the chamber (5), the pressure is lowered so as to exceed a predefined setpoint, and is brought back to the setpoint only if the temperature has stabilized.

Description

"CONTROL SYSTEM AND METHOD FOR ADJUSTING AIR PRESSURE IN A VEHICLE WHEEL"

Cross-Reference To Related Applications

This Patent Application claims priority from Italian Patent Application No . 102023000012738 filed on June 20 , 2023 , the entire disclosure of which is incorporated herein by reference .

Technical Field

The present invention concerns a control system for adj usting air pressure in a vehicle wheel .

In particular, the present invention refers to a control system in which the wheel has an electric power supply battery, a motori zed compressor for trans ferring air into a reservoir, and an adj ustment valve which is controlled so as to manage an air flow from the reservoir to the air chamber defined by the tire .

More speci fically, the adj ustment of the pressure carried out by the control system also takes account of the temperature detected by a sensor mounted on board the wheel .

Prior Art

To adj ust the pressure inside tires , solutions are known with a centrali zed architecture on board the vehicle , having one single reservoir and one single compres sor, controlled by a control unit so as to be activated and to supply compressed air into such reservoir . The reservoir is then connected to the wheels by respective ducts provided with valves , which are also controlled by the above-mentioned control unit to adj ust the compressed air flow : such valves are switched to determine inflation or to determine discharge of air from the respective tire towards the outside .

Furthermore , another valve pneumatically connects the compressor to the reservoir so that the two components can be isolated when required . With respect to this type of centrali zed solution, it is preferable to adopt inflation and deflation systems that are arranged directly on board the wheel in order to reduce the number of components , reduce the overall dimensions on board the vehicle and avoid the passage of compressed air between a fixed part , namely the vehicle body, to a rotating part , namely the wheel .

In the context of these decentrali zed solutions , the document EP0621144 discloses an example in which a two-way compressor is provided on board the wheel , which trans fers air between the air chamber in the tire and an additional annular chamber, integrated in the wheel rim and defining a reservoir for storing the air . Another example disclosed by EP0621144 , namely the one of figure 2 , entails the use of a one-way compressor and an additional pneumatic line , which connects the air chamber of the tire to the annular reservoir integrated in the rim, in parallel with the compressor . A valve controls the passage of the air in such line to inflate the tire . In both these solutions , to adj ust the pressure in the tire , the air is exchanged between the air chamber and the reservoir integrated in the rim, without contaminating the external air .

Given the limited capacity of the electric power supply battery, carried on board the wheel , it is expedient to limit the number of activations o f the compressor and/or of the above-mentioned valve . In this context , the air temperature inside the tire must also be taken into account in adj usting the f lows of the compressor and/or the valve . In fact , the temperature variations are relatively s low during use of the vehicle, but lead to internal pressure variations that can be signi ficant , hence there is the ri sk that the adj ustment system, which aims to maintain a given fixed pressure setpoint , cuts in repeatedly, to make continuous corrections to the pressure inside the tire during such temperature variations . The need is therefore felt to solve this potential drawback, above all to limit the consumption of the power supply battery .

The obj ect of the invention is to meet the above-mentioned need, preferably in a simple and/or ef fective and/or inexpensive manner .

Summary of the Invention

The above-mentioned obj ect is achieved by a control system and by a control method as defined in claims 1 and 7 respectively .

The dependent claims define particular embodiments of the invention .

Brief Description of the Drawings

Below, for a better understanding of the present invention, preferred embodiments will be described by way o f non-limiting examples , with reference to the attached drawings , in which : figure 1 illustrates , in perspective and with parts removed for clarity, a vehicle wheel ;

- figure 2 is a radial direction view of the wheel of figure 1 ;

- figures 3 and 4 are diagrams relative to the operation of an assembly provided on board the wheel , for adj usting the air pressure in such wheel ; and

- figure 5 illustrates graphs relative to an operation example , in which the pressure of the air inside the wheel is adj usted considering the temperature detected by a sensor, according to the teachings of the present invention .

Detailed Disclosure of Preferred Embodiments of the Invention

In figure 1 , the reference number 1 indicates , overall , a vehicle wheel , partially illustrated .

With reference to figure 2 , the wheel 1 has an axis 2 , coinciding, in use , with its rotation axis , and comprises a rim 3 and a tire 4 ( i llustrated by a broken line and in a simpli fied manner ) , fitted on the rim 3 so as to define , together with the latter, a chamber 5 which is filled with air and can be pressuri zed from the outside via a valve 6 ( figure 1 ) . The valve 6, of known type , is generally carried in a fixed relative position by the rim 3 .

In particular, the rim 3 has an outer annular wall 7 , which radially delimits the chamber 5 and is shaped so as to comprise an intermediate portion 8 and two shoulders 9 arranged at the opposite axial ends of the rim 3 . Such shoulders 9 protrude radially outwards with respect to the intermediate portion 8 ; furthermore , at the shoulders 9 , the wall 7 defines two concave areas 10 , which are shaped so that beads of the tire 4 can be coupled in a sealed manner, according to shapes and techniques which are known and not described in detail . Furthermore , again according to already known configurations , the intermediate portion 8 of the wall 7 is shaped so as to define an annular channel 11 , forming part of the chamber 5 and connected to the areas 10 by respective portions 12 and 13 of the wall 7 . In particular, the portion 13 has a flared shape , for example a f rustoconical shape , which diverges from the channel 11 towards the corresponding axial end of the rim 3 ; furthermore , more in particular, the portion 12 has an axial dimension smaller than the one of portion 13 ; in use , the portion 13 faces axially towards the body of the vehicle on which the wheel 1 is mounted, while the portion 12 faces axial ly towards the outside of the vehicle , namely towards an axial end of the rim 3 provided with spokes 15 ( figure 1 ) .

The wheel 1 further comprises an assembly 20 for automatically adj usting the pressure in the chamber 5 , for example to maintain it within a predefined setpoint range and/or to maintain it as close as possible to a predefined setpoint value , during use (namely during the vehicle j ourneys ) .

Therefore , the assembly 20 is carried on board the wheel 1 and rotates together with the rim 3 about the axis 2 during use . The assembly 20 comprises at least one motori zed compressor 21 ; at least one reservoir 22 defining at least one chamber with substantially fixed volume , separate from the chamber 5 and from the external environment ; at least one battery 24 to supply electric power to the electric motor of the compressor 21 ; and a microprocessor 25 ( schematically illustrated) , which controls such electric motor in response to control signals emitted in wireless mode by an emitter (not illustrated) arranged in a fixed position on board the vehicle and/or in response to operations carried out by a control strategy stored in a memory forming part of the same microprocessor 25 .

This architecture is therefore of decentralized type , since the assembly 20 is mounted on each of the wheels of the vehicle and is without pneumatic connections and/or electric connections with the fixed part of the vehicle .

The microprocessor 25 is configured so as to operate the motor of the compressor 21 and therefore activate the latter, for example in response to a control signal and/or a reference signal ( setpoint ) provided by the vehicle dashboard, to supply pressuri zed air from the chamber 5 to the reservoir 22 , and not vice versa .

According to an embodiment of the present invention, in fact , the compressor 21 is one-way, namely it is built and mounted so that it can supply a flow of air in one single direction ( from the chamber 5 to the reservoir 22 ) .

The assembly 20 further comprises a solenoid valve , indicated in figure 2 in a simpli fied manner by means of the reference number 26 , which switches , under the control of the microprocessor 25 , between a closed configuration and an open configuration in order to allow an air flow from the reservoir 22 to the chamber 5 , namely in the opposite direction to the one set by the compressor 21 . According to an embodiment of the present invention, the microprocessor 25 is configured so as to check also the air temperature inside the chamber 5 , by means of at least one temperature sensor 29 ( schematically illustrated in figure 2 ) , connected in wireless or wired mode to communicate with such microprocessor 25 , or integrated in the microprocessor 25 , for correction of the pressure of the air to be supplied/discharged and/or for any correction of the setpoint values , according to the detected temperature .

Furthermore , the microprocessor 25 is connected, in wireless or wired mode , to communicate with at least one pressure sensor mounted on the wheel 1 . The pressure sensor can be of known type , usually cal led TPMS , usually installed in the area of the valve 6 . In other words , the microprocessor 25 interacts with such sensor to receive detection of the pressure values inside the chamber 5 .

The control algorithms implemented in the microprocessor 25 , and/or control signals coming from a fixed control unit , on board the vehicle , are configured so as to inflate and deflate the chamber 5 , namely adj ust the air pressure inside it , preferably with air quantities/pressures such as to optimi ze adherence to the ground during use , also according to the type of ground or according to a command by the driver indicative of such type ( for example , on mud or on sand it is expedient to reduce the pressure , whereas on asphalt the pressure should be higher to reduce rolling resistance ) .

As mentioned above , the air in the chamber 5 , previously supplied from the outside through the valve 6 , is pumped from the compressor 21 and trans ferred into the reservoir 22 so as to reduce the pressure , namely to deflate the tire 4 , as shown in figure 3 .

Analogously, by controlling the solenoid valve 26 , which is arranged at the outlet of the reservoir 22 , an air flow is permitted from the reservoir 22 ( at higher pressure ) towards the chamber 5 ( at lower pressure ) , and therefore the pressure in the chamber 5 increases : in other words , the tire 4 is inflated, as shown in figure 4 .

Preferably, the microprocessor 25 is configured with appropriate control algorithms to carry out diagnoses of the whole assembly 20 and transmit , to a control unit on board the vehicle ( and then to the dashboard of the passenger compartment ) , information concerning any mal functions and/or information relative to the adj ustment phases and stand-by phases between two successive adj ustments .

The assembly 20 further comprises a system (not illustrated) for recharging the battery 24 . In particular, such system is of the induction type and/or is arranged in the area of an outer surface of the wheel 1 to be coupled to the domestic electric power supply, or to a power supply device of the vehicle ( for example a cigarette lighter ) , only with the vehicle at a standstill . Other recharging systems can be provided, however, for example exploiting the rotation of the wheel 1 to generate energy for the battery 24 .

I f the vehicle is provided with a traditional kit for repairing the tire 4 in the event of a puncture , the components of the assembly 20 must be appropriately chosen so as to be compatible with the chemical products ( for example , a mixture of water, latex and ethylene glycol ) used in such repair kits .

With reference to the graphs of figures 3 and 4 , mentioned above , the pressure in the reservoir 22 increases more than the pressure in the chamber 5 decreases , given the same quantity of air in and out respectively, since the volumes in the reservoir 22 are smaller than the one of chamber 5 , and the pressure in the reservoir 22 is much higher than the one in the chamber 5 . Figure 3 shows what happens during deflation : in the first graph starting from the top, it can be seen that the pressure of the chamber 5 drops , for example from 3 bar to 1 . 5 bar, while the pressure in the reservoir 22 ( third graph) increases , for example from 3 bar to 20 bar, namely to a relatively high value . This occurs when the compressor 21 is operated ( second graph) , as mentioned above . At the same time , the solenoid valve 26 remains in an inactive condition, namely closed ( fourth graph) .

Preferably, therefore , the air compressed by the compressor 21 arrives in the reservoir 22 without switching any valve , but only operating the compressor 21 .

During the inflation, as shown in the first graph at the top of figure 4 , it can be seen that the pressure of the chamber 5 increases to the desired setpoint value , for example 3 bar, due to the flow coming from the reservoir 22 . At the same time , the compressor 21 remains deactivated ( second graph of figure 4 ) and the pressure of the reservoir 22 ( third graph) drops , for example from 20 bar to 3 bar .

Going back to the control algorithms , the latter are implemented in the microprocessor 25 or in a fixed control unit , on board the vehicle , communicating with the microprocessor 25 in wireless mode , as mentioned above .

Such control algorithms , when run, are configured so as to adj ust the pressure in the chamber 5 in response to a pressure signal provided by the above-mentioned pressure sensor and reach a preset reference value ( setpoint ) . such reference value can be defined based on the vehicle conditions , road conditions , etc...

Furthermore , as mentioned above , adj ustment of the pressure in the chamber 5 is carried out also in response to the temperature signal provided by the sensor 29 . According to an embodiment of the present invention, when it is detected that the temperature in the chamber 5 is increasing or decreasing, during such temperature variation the pressure corrections in the chamber 5 are carried out by the microprocessor 25 (commanding the compressor 22 and/or the solenoid valve 26) so as to exceed the setpoint .

In this way, a pressure limit value is reached that is distanced from the setpoint by a deviation or tolerance value having a predefined entity. By way of example, such deviation or tolerance is approximately 0.1-0.2 bar.

By way of example, figure 5 shows an event with temperature increase, in the third graph from the top: such increase is assumed to be linear (namely with constant derivative of the temperature trend over time) for the sake of simplicity.

In the first graph starting from the top, it can be noted that, when the control is activated (see fourth graph) , the pressure is adjusted so that it is lowered, causing air to flow from the chamber 5 to the reservoir 22 by means of the compressor 21, to approach the setpoint (indicated as "selected pressure") . Since the air temperature in the chamber has 5 has increased, however, the pressure adjustment performed by the microprocessor 25 does not stop when the setpoint is reached, but continues to a lower limit value which has a predefined deviation with respect to the setpoint, for example 0.1 bar.

When such lower limit is reached, the adjustment stops, namely the compressor 21 is deactivated.

At this point, in the example illustrated, the temperature is still increasing. Therefore, the air pressure in the chamber 5 tends to increase naturally, starting from the lower limit value that had been achieved via a first adjustment. This natural increase causes the pressure to reach and exceed the setpoint. In this phase the microprocessor 25 does not intervene.

In fact, the microprocessor 25 is configured to intervene again with a second adj ustment only when the air pressure in the chamber 5 reaches an upper limit value that is distanced from the setpoint by a deviation or tolerance that has a predefined entity . This deviation has an entity analogous to the one indicated above by way of example for the lower limit value ( approximately 0 . 1- 0 . 2 bar ) , in absolute value . The lower limit value and the upper limit value mentioned above are arranged below and above the setpoint respectively, namely straddling the latter .

To summari ze : the pressure adj ustments are interrupted when the air pressure in the chamber 5 naturally reaches the lower limit value and are reactivated (by operating the compressor 22 again) when the pressure reaches the upper limit value , due to the temperature increase . With this reactivation, the lower limit value is re-set , starting from the upper limit value ( in particular, i f the temperature is still increasing) .

Consequently, in the presence of a temperature variation, in practice the control algorithms no longer consider a speci fic setpoint value ( the one indicated as " selected pressure" in figure 5 ) , but they consider a reference range and allow the pressure in the chamber 5 to oscillate between the extremes of this reference range as long as the temperature is increasing, without attempting to reach and rigorously maintain such precise setpoint value .

In other words , the sequence of successive adj ustments causes the pressure to oscillate around the setpoint value (" selected pressure" ) : in this way the overall number of activations of the compressor 22 are reduced .

According to a preferred embodiment of the present invention, when the air temperature in the chamber 5 stabili zes , the microprocessor 25 is configured so as to carry out a fine adj ustment , bringing the pressure in the chamber 5 back to the precise setpoint value (" selected pressure" ) . In particular, the microprocessor 25 is configured so as to bring the pressure to the setpoint value i f the air temperature in the chamber 5 remains constant for a time interval above a given threshold ( for example 5 minutes ) , stored together with the control strategies . I f such time threshold is not reached, the microprocessor 25 does not carry out any fine adj ustment , therefore the air pressure in the chamber 5 will be within the range between the upper limit value and the lower limit value , and not at the precise setpoint value .

All the veri fications and calculations on the temperature values are carried out considering a tolerance margin, for example 5 ° C, so as to render the control stable . In other words , temperature variations below this tolerance margin are not considered as a real temperature increase ( or decrease ) .

In the case of a temperature decrease , instead of an increase as hypothesi zed in figure 5 , the control system could theoretically operate analogously ( causing the pressure to oscillate within a reference range ) : however, the application of this control strategy to a temperature decrease is not necessary, since normally the temperature decreases occur with the vehicle at a standstill , and therefore with the control system deactivated .

As already illustrated above , by introducing a reference range , which has a certain tolerance with respect to a precise setpoint value , it is possible to reduce the number of adj ustment interventions by the compressor 22 , particularly in the case of deflation, in the presence of a temperature variation .

Despite the introduction of this tolerance , the control system is configured to perform a fine adj ustment , or a final adj ustment , to achieve the precise desired pressure value when the temperature has stabili zed .

Furthermore , the deviation between the setpoint and the pressure limit values in which the adj ustments start and finish, namely the deviation between the setpoint and the extremes of the reference range , can be calibrated and set at the design stage so as to achieve the best compromise between the lowest number of interventions of the compressor 22 and guarantee of the roadholding conditions due to the ef fective internal pressure in the tire .

Other advantages are evident to a person skilled in the art based on the above description .

Lastly, it is clear that modi fications and variations that do not depart from the protective scope defined by the attached claims can be made to the wheel 1 according to the present invention .

In particular, di f ferent methods could be used for trans ferring the air from the reservoir 22 to the chamber 5 during inflation of the wheel 1 , for example by exploiting the passage defined by such compressor 21 ( and i f necessary excluding the solenoid valve 26 ) .

Claims

1.- Control system comprising:

A) a vehicle wheel (1) comprising:

- a rim ( 3 ) ,

- a tire (4) defining, together with said rim (3) , a chamber (5) , which is filled with air and can be pressurized,

- an assembly (20) for adjusting air pressure in said chamber (5) , the assembly comprising: a) at least one compressor (21) having:

(1) an inlet, pneumatically connected to said chamber ( 5 ) , and

(2) an outlet; b) at least one reservoir (22) carried by said rim (3) , pneumatically connected to said outlet to receive compressed air from said compressor (21) and pneumatically connected to said chamber (5) to transfer air to said chamber (5) ; and c) at least one battery (24) for supplying electrical power;

B) an electronic control unit (25) , arranged on said wheel (1) or on a vehicle equipped with said wheel; said electronic control unit (25) being configured to adjust the pressure in said chamber (5) by airflows from said chamber (5) to said reservoir (22) and vice versa, in response to a pressure signal indicative of the air pressure in said chamber in order to achieve a reference value which is preset or memorized; characterized by the fact that

- said assembly comprises a sensor (29) for determining the temperature of the air in said chamber (5) , and

- said electronic control unit (25) is configured so that, when the pressure in said chamber (5) is lowered, the pressure of the air in said chamber (5) exceeds said reference value and reaches a pre-defined lower pressure value, if there is an increase in temperature of the air in said chamber (5) .

2.- The control system according to claim 1, wherein said electronic control unit (25) is configured to interrupt the adjustment, until the pressure of the air in said chamber (5) naturally reaches a pre-defined higher pressure value, from said lower pressure value, due to said temperature increase.

3.- The control system according to claim 2, wherein said upper pressure value is greater than said reference value.

4.- The control system according to claim 3, wherein said upper pressure value and said lower pressure value differ from said reference value by an equal deviation in absolute value.

5.- The control system according to any one of claims 2 to 4, wherein said electronic control unit (25) is configured to repeat the pressure adjustment and reset said lower pressure value if said temperature increase is still present when said upper pressure value is reached.

6.- The control system according to any one of the preceding claims, wherein said electronic control unit (25) is configured to adjust the air pressure in said chamber (5) to said reference value if the temperature has remained constant for a time interval above a given threshold.

7.- A control method for adjusting pressure in a vehicle wheel (1) , which comprises:

- a rim ( 3 ) ,

- a tire (4) defining, together with said rim (3) , a chamber (5) , which is filled with air and can be pressurized,

- an assembly (20) for adjusting the air pressure in said chamber (5) , the assembly comprising: a) at least one compressor (21) having:

(1) an inlet, pneumatically connected to said chamber

( 5 ) , and

(2) an outlet; b) at least one reservoir (22) carried by said rim (3) , pneumatically connected to said outlet to receive compressed air from said compressor (21) and pneumatically connected to said chamber (5) to transfer air to said chamber (5) ; and c) at least one battery (24) for supplying electrical power; d) a sensor (29) for determining the temperature of the air in said chamber (5) , the method comprising the steps of lowering the pressure in said chamber (5) so as to exceed said reference value and reach a lower pressure value, if there is an increase in temperature of the air in said chamber (5) .

8.- The control method according to claim 7, wherein the control is interrupted until the pressure of the air in said chamber (5) naturally reaches a higher pressure value from said lower pressure value due to said temperature increase.

9.- The control method according to claim 8, wherein said upper and lower pressure values straddle said reference value.

10.- The control method according to claim 9, wherein said upper and lower pressure values have an equal deviation, in absolute value, from said reference value.

11.- The control method according to any one of claims 8 to 10, wherein the air pressure in said chamber (5) is re-adjusted so as to be lowered to said lower pressure value from said upper pressure value if said temperature increase is still present.

12.- The control method according to any one of claims 7 to 11, wherein the air pressure in said chamber (5) is adjusted to reach said reference value if the temperature has remained constant for a time interval above a given threshold.