MXPA00011546A - Device capable of signalling the inflating condition in the tires - Google Patents

Abstract

A device capable of signalling the inflating condition in the tires comprises:an external envelope (1) rotating with a threaded body (4) which can be screwed on a jointing tube (5) of an inflating valve (6);a plunger (11) fitted with a housing (17) closed by a deformable lamina (18);a bellows (10) separating a first chamber (20) located over the plunger (11) from a second chamber (15) defined under the plunger (11);the lamina (18) presents a downward bending when the atmospheric pressure acts on the housing (17) and the tire pressure acts on the first chamber (20) having a value higher than a pre-established value;a third chamber (16) connected to the first chamber (20) is delimited by the external wall of the bellows (10) and the internal wall of the envelope (1);a fourth chamber (26) is found inside the tube (5), the chamber (26) being separated from the second chamber (15) when the rod of the plunger (11) seals a gasket (25);ducts (12, 14, 21) connect the chambers (16, 20) to the chamber (15) and the atmosphere (27) when the tire pressure falls below a pre-established value.

Description

DEVICE ABLE TO INDICATE THE INFLATION CONDITION ON THE RIMS BACKGROUND OF THE INVENTION The present invention relates to a device capable of indicating the inflation condition in tires; this device comprises an external cover, capable of rotating together with a threaded body, which is used to screw the device onto the body of a standard inflation valve, a chamber, defined within the threaded body, a pressure sensitive element that There exists in the chamber, a member, which can be deformed by the pressure, which considers the temperature, and a system capable of indicating the position of the deformable member.

SITUATION OF THE TECHNIQUE The patent US-A-5, 694, 969 refers to a device for inflating a rim of a wheel. A tire pressure relief valve for inflating a tire wheel assembly has a tire inflation valve body having a chamber with openings through its top and bottom ends and having a relief opening, formed in the valve body of the rim. An inflation valve having a spring-loaded central core, to allow passage to the interior, is located in the rim valve body, adjacent to the upper end of the tire inflation valve body, to inflate the rim through of the same. An overpressure valve is located in the valve body of the rim, to release air from the rim, when the air pressure in the rim exceeds a predetermined level. The overpressure valve d has a valve seat and a valve element oriented against it by compression, to maintain the valve member in the closed position, until the predetermined air pressure reaches the rim and allow the valve element to pass. Valve opens to release air through the relief opening of the valve body, when there is air pressure in the rim and allows the valve element to open to release air through the relief opening of the valve body, when the air pressure in the tire exceeds the predetermined pressure. A variable heat bellows supports the compression spring and is responsible for air temperature changes in the rim, so the overpressure valve can prevent over-inflation of the rim, as well as the loss of pressure in the tire. the rim, when the air pressure in the rim increases due to an increase in the air temperature in the rim.

This and other prior art documents do not refer to a device for indicating the inflated state in the tires, but to a set that limits the pressure, in the case of an excessive increase in the temperature of the air tube.

OBJECTS AND CHARACTERISTICS OF THE INVENTION The present invention, as claimed, solved the problem of creating a device capable of indicating the inflation condition in the tires. The results obtained by means of the present invention consists mainly of the fact that the function of controlling to automatically prevent the escape of air from the tire continues to be effected by the self-closing core of the inflation valve, also in the presence of the device, which, therefore, is used only to indicate if the tire pressure is correct or not, without introducing the risk that the tire will be deflated in the event that the same device presents an escape. The advantages offered by the invention consist in the fact that the pressure of the rim is indicated by considering at least one threshold value; Above this old revision value, the device indicates the normal state of inflation of the tire, while the same device indicates the inflated state not correct when the tire pressure is below the same threshold value or another previously established value, less than previous threshold value; u element that detects the temperature allows to consider the temperature to define the threshold values, while a signaling system indicates whether the inflation condition of the tire is correct or not.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages, features and objects of the invention can be understood more easily by referring to the accompanying drawings, which refer to a preferred embodiment, in which: Figure 1 represents the device before its tightening on The valve; Figure 2 represents the device after its tightening; Figure 3 shows the device during the loading phase; Figure 4 represents the device after the loading phase; Figure 5 demonstrates the behavior of the device when the tire pressure has reached a value below a previously established threshold; Figure 6 shows the device after decreasing the tire pressure below the threshold value.

DESCRIPTION OF A PREFERRED MODE OF THE INVENTION The device, according to the invention, consists of an external envelope 1, whose upper wall 2 is preferably transparent; this casing 1 rotates with a threaded body 4, which can be screwed onto the threaded joint tube 5 of the inflation valve 6; this valve 6 has a self-closing valve core 7, tensioned by a spring 8. The core 7 of the self-closing valve automatically prevents the escape of air from the rim, allowing it to be inflated. The outer casing 1 can slide axially with respect to the threaded body 4, being held in a limit stop stable with respect to the same body 4 by means of a spring 9; the seal between the casing 1 and the threaded body 4 is secured by a toroidal packing 3. A bellows 10 connects the threaded body 4 to a plunger 11, where three internal ducts 12, 13, 14 are bored. This bellows 10 allows frictional axial sliding of the plunger 11 within the device; furthermore, the bellows 10 separates two chambers, 15, 20; the chamber 15 is under the plunger 11 and inside the bellows 10, while the chamber 20 is located on the plunger 11 and is connected to the chamber 16 with continuity; the chamber 16 is placed outside the bellows 10, in this way, the piston 11 can be moved axially by the pressure differences that take place between the chamber 15 (lower) and the chamber 20 (upper). In one embodiment, not shown, the function of the bellows 10, which consists of separating the two chambers 15, 20, placed, respectively, under and on the plunger 11, is carried out by a sliding packing, which causes friction when the plunger 11 moves. The upper part of the plunger 11 has a housing 17 closed by a sheet 18, which can be deformed; A toroidal packing 19 secures the seal between the internal part of the housing 17, closed by the sheet 18 and the chamber 20, which is placed between the upper wall 2 and the sheet 18, the chamber 20 being connected directly to the chamber 16. channel 21 connects the housing 17 with the conduit 13 that goes inside the plunger rod 11; this rod presents two portions with different external diameters. The sheet 18 controls the channel 21 by means of a bistable valve 22 equipped with a double closing device, the valve 22 being operated by the same sheet 18, which presents a first stability position, when a first section of the lock device, it closes the connection between the housing 17 and the channel 21, allowing the connection between the conduit 13 and the channel 21, and a second stability position, when a second section of the lock device closes the connection between the conduit 13 and it channel 21 , allowing the connection between the housing 17 and the channel 21. The conduit 14 connects the internal part of the housing 17 to the chamber 15, placed below the piston 11 and inside the bellows 10, the conduit 14 being controlled by a self-regulating valve 23. closing, which allows air passage from the housing 17 inside the chamber 15, but not vice versa. The conduit 12 connects the chambers 16 (located on the outside of the bellows 10) and 20 (located on the piston 11) to the channel 21, where the rod 24 of the bistable valve 22, with double closing device is inserted. The cover 1 transmits a torsion of the threaded body 4, ie a rotation; in practice, when the device is screwed onto the valve 6, the valve 6 is screwed onto the cover 1 with the fingers, in order to transmit the torsion, which causes the rotation of the threaded body 4 to hold the package 25 used for sealing the body of the valve 6 with respect to the device. A chamber 26 is defined within the joint tube 5 of the inflation valve 6, the chamber 26 is separated from the chamber 15 only if the plunger 11 is at the bottom limit stop, so the section of its rod that has the larger diameter holds the inner edge of the gasket 25. When the gasket 25 is fully clamped, the chamber 15 located inside the bellows 10 is connected to the atmosphere 27 through a conduit 28, a groove 31 and a channel 29. duct 28 is controlled by a self-closing valve 30, which is in the open position, to allow air to flow within chamber 15 to channel 21 and channel 29, / / consequently to atmosphere 27, only if the package 25 has been fully secured; in the case of insufficiently holding the package 25, the valve 30 does not open, therefore, the passage of air from the chamber 15 to the channel 21 and to the channel 29, and consequently to the atmosphere 27, is impeded; this occurs even in the case of incompletely fastening by the gasket 25, as long as the gasket 25 is brought into contact with the threaded joint pipe 5. The device, shown in Figure 1, has not yet been fastened on the valve 5, 6; in this case, the attempt to charge the device causes no effect, therefore, the device is automatically discharged, since, on the one hand, the camera 26, the conduits 13, 21, 12 of the camera 16 and the camera 20 , placed on the piston 11, do not maintain the pressure of the rim, due to the escape of the air that takes place between the package 25, subject insufficiently, and the valve body 5, with the consequent blow and the direct discharge to the atmosphere through the channel 29, and, on the other hand, the discharge to the atmosphere of the chamber 15, placed below the plunger 11, can not occur (during transient loading, the chamber 15 is subjected to the air tube pressure before being isolated from the chamber 26 at the instant when the piston rod portion 11, having the largest external diameter, holds the inner edge of the gasket 25); in fact, the valve 30 remains closed, since it opens only due to the clamping compression of the package 25 and due to the thrust applied on the same valve 30 by the pressure that exists inside the chamber 15. Furthermore, if the packing 25 on the threaded joint tube 5 is incomplete, so that the puff occurs towards the channel 29 and the slot 31, the air will also tend to flow back to the chamber 15 through the slot 31 and will cause the losses of pressure due to the inverse flow through the channel 29. The direct balance between the pressure losses in the channels 28, 29, can ensure the discharge of the device by insufficient fastening of the package 25, even in the case of the absence of the valve 30 self-closing. For this reason, it is possible to immediately understand that the device is insufficiently tightened, in any case, situations of risk of deflation of the rim due to insufficient tightening will not occur. Figure 2 shows the device after a tightening; after the complete screwing of the device in the valve 5, 6 of the rim and, therefore, obtaining adequate tightening of the package 25 through the screwing of the body 4 in the valve 5, 6, the device is ready to work. In the condition of Figure 2, the device works exactly like a cap on a traditional tire inflation valve, i.e., the device does not perform any function, and is only used to protect the valve. The valve 5, 6 of the rim is closed by the self-closing valve core 7, therefore, the air tube is not connected to the chamber 26 nor to the atmosphere. Usually, the sheet 18 is folded upwards; this bending is maintained until the pressure in the chamber 20 has reached a sufficiently high value with respect to the value of the pressure that exists in the housing 17 (that is, the atmospheric pressure, since the housing 17 is connected to the atmosphere , as will be more readily understood with reference to the following description), therefore, when the value of the pressure is sufficiently high, the bending is directed downwards. In fact, the folding of the sheet 18 depends on the difference between the pressure in the chamber 20, which will successively be connected to the air tube of the rim, and the pressure in the housing 17, which will be connected to the atmosphere. If this pressure difference, which can advantageously be corrected, considering the value of the temperature in the case of the balanced measurement made by a bimetal 18, is sufficiently high, the bimetal 18 will bend downwards, reaching a position of doubled towards below stable, shown in Figures 3 and 4, which represent the operation of the device, otherwise, the bimetal 18 will remain in its configuration bent upwards. The subsequent operation consists of loading the device; this operation takes place (Figure 3) by means of a manual external axial thrust P, which causes the axial movement of the outer shell 1 with respect to the threaded body 4, by exceeding the thrust of the spring 9. Because the thrust P is applied on the external body of the device (outer shell 1, wall 2) also the plunger 11 moves downwards by the thrust P, transmitted to the sheet 18, through the upper wall 2; due to the push P, the sheet 18 bends down just as it would if the pressure in the chamber 20 were sufficiently greater than the pressure in the housing 17. This is the loading operation, when the device is adjusted in the work, what happens if the difference between the pressure in the chamber 20, on the one hand, and the pressure in the housing 17 of the chamber 15, on the other, is sufficiently high. It should be noted that, in this first phase of the transient load, the difference between the pressure in the chamber 20, on the one hand, and the pressure in the chamber 15 the housing 17 (connected to each other through the conduct 14), another, has not yet happened and stabilized, therefore, the bending of the blade 18 and the movement downward of the plunger 11 occurs only due to the mechanical thrust P. This new geometric configuration of the blade 18, also causes the movement of the valve 22 equipped with a double closing device, towards the first stability position; therefore, the valve 22 connects with the conduit 13 to the conduit 12 and the chambers 16, 20, disconnects the joint between the channel 21 and the housing 17. It will be recalled that the chamber 20 extends from the upper surface of the sheet 18 to chamber 16, external to bellows 10 with continuity. In addition, because the same thrust P, the plunger 11 moves downward; therefore, the lower end of the piston rod (within which the conduit 13 is auger) pushes down the end of the core 7 of the self-closing valve, which opens to allow air inside the tube to fill the chamber 26, defined inside the joint tube 5 of the inflation valve 6. The gasket 25 is also capable of sealing the plunger rod 11 by means of its inner lip, only when the plunger 11, whose rod has two diameters, moves towards the low limit stop, shown in Figure 3 (loading position). ). Consequently, if at the beginning of the opening of the core 7 of the self-closing valve, during the downward movement of the plunger 11, the air exiting the tube fills the chamber 26, the chamber 15, the duct 28, the channel 29, the slot 31 (and the conduits 12, 13, the channel 21, and the chambers 16, 20, since these cavities are connected together), at the moment when the plunger 11 has reached its low limit stop and, therefore, both, the seal between plunger rod 11 and packing 25 is allowed, also the separation of the chamber 26 defined within the joint tube 5 of the inflation valve 6, takes place from the chamber 15 placed under the plunger 11 and inside the bellows 10. It is to be noted that the sealing on the plunger rod 11, which is necessary to isolate the chambers 26 and 15 when the plunger 11 is in the low limit stop, can be obtained by means of a different packing of the packing 25, for example, a toroidal packing, integral with the threaded body 4; The solution that consists of integrating the seal in the same package 25 allows the reduction of the axial dimensions. Once this condition is reached, the pressure that exists in the air tube is established in the chamber 26, the conduits 12, 13, and the chambers 16, 20; vice versa, the atmospheric pressure is established in the chamber 15 and the housing 17 and in the conduits 14, 28, 29 and the groove 31. Two cavities, therefore, have been separated, the first cavity 20 is on the piston 11 , while the second cavity 15 is placed under the plunger 11; This separation is due to the packing 25, on the one hand (which seals on the piston rod 11) and, on the other hand, the bellows 10 (which seals on the piston 11). When the external push P is removed, if the difference between the pressure in the chamber 20 the pressure in the housing 17 (that is, between the tube the atmosphere) is sufficiently high (remembering that the chamber 15, through the internal conduit 14 , it is also connected to the housing 17, which, in this way, is subjected to atmospheric pressure), the sheet 18 will keep the configuration bent downwards, because the push P, even when the same push P has been removed, and consequently the connection of the conduit 13 to the housing 17, through the channel 21, will be closed, but the connection of the conduit 13 to the conduit 12 (and, therefore, of the conduit 13 to the chambers 16, 20) through it channel 21, will be opened, thanks to the first stability position reached by the bistable valve 22 equipped with a double closing device. After releasing the thrust P, the spring 9 and the air pressure in the chambers 16, 20 move the outer shell 1 up again, which reaches its original position, shown in Figure 4. In this configuration, if the Air pressure (pressure of the air tube) exists in the chamber 20 (finally corrected, considering the value of the temperature in the case of a balanced measurement, made by a bimetal 18), it is such as to exert a tension on the surface upper of the sheet 18, this tension being sufficient to keep the sheet 18 bent downwards (in fact, the atmospheric pressure exists in the housing 17); this tension also keeps the plunger 11 held in its low limit stop, since, due to the difference in the active sections, the tension easily exceeds the thrust due to the pressure of the air tube in the plunger rod 11 and the thrust of the plunger 11. spring 8. In such form, the plunger rod 11 keeps the self-closing valve core 7 open to ensure the continuous connection between the air tube and the measuring system 16, through both the chamber 26 and the chamber 20, where there is the pressure of the air tube. Each air leak is obviously prevented by the seal, due to the gaskets 25, 19, 3 and the bellows 10. Consequently, as shown in Figure 4, while the pressure of the trowel (finally corrected, considering the value of the temperature) is maintained at a sufficient value, ie, above the set threshold value, which defines the low limit of the correct inflation pressure of the rim, the device will remain charged, that is, with the sheet 18 bent downwards and plunger 11 on its low limit stop; The same device will maintain the connection of the air tube through the core of the self-closing valve. It is necessary to specify that the utility of the function obtained by the device (that is, it indicates when the tire pressure falls below at least the previously established threshold value) is relative to all normal working conditions, where the deflation of the Tire takes place slowly, therefore, it is a difficult way to perc by means of common observation (phenomenon that takes place or will be the cause of natural acts, such as an escape through the structure of the same rim, or due to external causes, such as small punctures that cause slow deflation); therefore, the device allows the necessary duration to detect the signal and operate, as soon as possible, in order to restore the value of the most correct pressure (and / or repair in the case of an eventual puncture to prevent a forced stoppage of the vehicle). Obviously, the device will not offer any practical utility in the case of punctures or other serious phenomena that cause the deflation of the rim in such a fast manner, that the duration of detecting the signal and acting consequently is insufficient.

Naturally, the previously established threshold value, which defines the low limit of the correct inflation pressure, can be defined in such a way as to ensure that the signaling of exceeding the same threshold value occurs, when the value of the pressure in the tire is still high enough to allow the necessary duration to detect the signal and act in usual operating situations, when deflation takes place slowly. When the pressure (finally corrected, considering the value of the temperature) falls below the previously established threshold value (or below another lower threshold value than the previous one), as shown in Figure 5, the sheet 18 will be bent upwards. This bending will immediately enable the bistable valve 22 equipped with a double closing device, to automatically change from the first to the second stability position to close the connection between the duct 13 the chambers 16 and 20 (through the channel 21 and the duct 12); vice versa, the connection between the chamber 20 and the housing 17 (through the conduit 12 and the channel 21) remains open. This housing 17, through conduit 14, is connected to chamber 15, which, in turn, is connected to atmosphere 27 through conduit 28, channel 29 and slot 31.

The objective that will be obtained when this situation occurs in the safety closure of the tire; therefore, the rim is isolated from the environment by means of the self-closing valve core 7 to prevent any escape of air through the valve core 7 or the device. For this purpose, the device is planned so that the downward thrust action in the plunger group 11, due to the difference between the pressure in the upper chamber 20 (where the tube pressure exists) and the pressure in the chamber lower 15 (where the ambient pressure exists), when the difference in pressure between the chamber 20 and the housing 17 is able to keep the sheet 18 folded down, and is so high as to greatly exceed the upward thrust acting on the plunger 11; this thrust is caused by the valve core 7 driven upwards by the spring 8, the pressure of the air tube acting on the piston rod section 11 and the elasticity of the bellows 10, in this way, the piston 11 is guaranteed remains in the load position (low limit stop), even in the presence of external disturbances (vibrations, inertial forces, etc.). The beginning of the phenomenon that causes the discharge of the device is due to a change in the pressure of the tire (finally corrected considering the value of the temperature). referred to as the atmospheric pressure, this change being able to bend the sheet 18 upwards, when the pressure in the cavities 17, 14, 15, 28 and 29 still presents the atmospheric value and the pressure in the cavities 16, 20, 12, 21 , 13 and 25 presents the value of the air tube (which has just fallen below the established threshold). Under these conditions, the difference between the pressure in the upper chamber 20 (where the tube pressure exists) and the pressure in the lower chamber 15 (where the ambient pressure exists) acting on the plunger II is in any way still able to keep the plunger 11 in the loading position (ie, in the low limit stop); in fact, the planning of the active sections of the plunger III and the relative rod will be selected in such a way that a vector resulting from the various forces, listed above, acting on the piston 11, will be directed in some way downwards also for the tire pressure values lower than the threshold value previously established, while, once above the threshold value, the sheet 18 will be bent upwards. Since the device has been planned for a practical use in all normal working conditions, where the deflation of the tire takes place slowly, at the instant when the tire pressure (finally corrected, considering the temperature) passes to a value less than the threshold previously established for this purpose, the sheet 18 will immediately bend upwards, but the resultant of the forces acting on the plunger 11 (whose module will be changed in turn, but only in a very small amount, the phenomenon will be slow), s will always keep directed down; Also, the resultant will present a value such as to permanently keep the plunger 11 in the low limit stop, until the pressure in the upper chamber 20 falls considerably. This noticeable drop will occur as a direct direct consequence of the upward bending of the sheet 18. In fact, the movement towards the second positioned valve stability 22 equipped with a double closing device, consistent with the modification of the geometric configuration of the valve. Plate 18 will cause a sudden change in pressure within several cavities. The gap between the duct 13 (which remains in the pressure of the rim together with the chamber 26) and the chambers 16 and 20 (through the ducts 21 and 12) are disconnected, while the chambers 20 and 16 are emptied through of the same conduits 12 and 21, the housing 17 (which is now connected to the channels 21 and 12), the conduit 14, the chamber 15 and the channel 28, the slot 31 and the channel 29, which are connected directly to the atmosphere 27. In this way, the pressure in the chamber 20 rapidly heats up, while, due to the pressure losses which obstruct the flow of air to the atmosphere 27 through the conduit 28, the annulus 31 and the channel 29, pressure in chamber 15 tends to increase (previously the pressure in chamber 15 presents the atmospheric value). This phenomenon associated with the upward thrust acted on the plunger rod 11 by the self-closing valve core 7, driven by the spring 8 and the bellows 10, causes the sudden upward stroke of the plunger 11 towards its lower limit top. As soon as the rising stroke of the plunger 11 begins, the rod with the two diameters is uncoupled from the package 25; in this way, a direct connection is created suddenly between the chamber 26, which until the core 7 of the self-closing valve closes, remains at the pressure of the rim and is potentially fed by a considerable air flow and the chamber 15 located under the plunger 11. In this way, the pressure in the chamber 15 immediately reaches the pressure value of the rim by exerting an ascending tension in the plunger 11; this value of the pressure is maintained until the core 7 of the self-closing valve closes completely, to reach the scope of the present invention, while the self-closing valve 23 prevents air from flowing to the housing 17 and from there, through the ducts 21 and 12, the air can reach the chamber 20, located on the plunger 11, where meanwhile the pressure has fallen with respect to the value of the rim presented before exceeding the threshold. In this way, the plunger 11, until the self-closing valve core 7 is completely closed, to be subjected to a resultant upward thrust, this resulting thrust is due to the difference between the pressure in the chambers 15 and 20 more the thrust applied to the needle of the core 7 of the self-closing valve, tensioned by the spring 8 the thrust of the bellows 10, this resultant thrust being sufficient to move the plunger 11 upwards, even if an identical pressure value must be found in the chambers 15 and 20. In fact, the pressure in the chamber 15 remains in the value of the rim, since the outflow from the self-closing valve core 7 still open is much greater than the leakage flowing towards it. the atmosphere through conduit 28, slot 31 and channel 29; this fact ensures that, even if the pressure in the chamber 20 must drop by a small amount or, still, the value of the tube reverses the air at the time, when the decoupling of the plunger rod 11 from the packing 25 occurs, as occur if the self-closing valve 23 is removed, the resultant of the stresses acting on the plunger 11 will be somehow directed upwards, thanks to the elastic action of the spring 8 and the bellows 10.

This being done causes the sudden upward stroke of the plunger towards its high limit stop and the closure of the self-closing valve core 7, obtaining the desired result and the discharge of the device; when the core 7 of the self-closing valve closes, both chambers 20 and 15 are suddenly connected to ambient pressure (atmospheric pressure), while the plunger 11 completes its upward stroke until it reaches the high limit stop, thanks to the elasticity of bellows 10 (Figure 6). In this way, the tire is immediately isolated from the environment; therefore, the self-closing valve core 7 always performs its safety and closing function against the air escaping through the inflation valve. This fact prevents any risk due to eventual leaks in the device. If the piston 11, after the loading phase, remains in the position such as to keep the core 7 of the self-closing valve open, ie in its low limit stop, this means that the pressure in the air tube (finally corrected, considering the value of the temperature) is greater than the previously established threshold value, which defines the low limit of the correct inflation tire pressure; vice versa, when the plunger 11 moves back to the high limit stop (ie discharges) the pressure in the air tube (finally corrected, considering the value of the temperature) is less than the previously established threshold value, or other threshold value previously defined, lower than the previous one. Then it is sufficient to detect either the folding of the sheet 18 or the position of the plunger 11 (which stroke is a few millimeters) to indicate whether the threshold value is exceeded externally with known means, this threshold value defines the low limit of the correct tire pressure. For example, a chromatic variant in the function of the position of the plunger 11 can be displayed in a transparent viewer applied to the wall 2. Furthermore, the displacement of the plunger 11 (or the change in the geometrical configuration of the sheet 18) can be adjusted in work an electrical circuit by means of which the emission of optical and / or acoustic signals can be obtained, these signals will be transmitted by induction, or hertzian waves, etc., with all possible combinations. The device can obviously be recharged infinity of times; All the times that the condition of exceeding the threshold value occurs, they will be downloaded automatically and will remain unloaded until the subsequent manual loading, ensuring that the signal can be received. Figure 6 shows the device after the pressure drop of the rim; in this case, the components of the device are again in the position of Figure 2.

Claims (10)

1. CLAIMS 1. A device capable of indicating the condition of inflation in the tires, characterized by the fact that it comprises: an external cover, which rotates together with a threaded body, which can be screwed onto a union pipe of a valve inflated, presenting a self-closing valve core, tensioned by a spring; or piston, which can be disposed in a first limit stop, this piston being used to keep the self-closing valve core open by means of a rod, which has two sections with different external diameters, if the difference between the pressure of the tire and the atmospheric pressure, exceeds at least one threshold value previously established; an element, with a variable geometrical configuration, which closes a housing, this geometric configuration of the element depends on the difference between the pressure of the rim and the atmospheric pressure, this element presents a first geometric configuration when atmospheric pressure acts on the housing , and the pressure of the rim is greater than the previously established higher threshold value, and a second geometric configuration, when the tire pressure is below the previously established lower threshold value; a sealing member, separating a first chamber, defined under the piston, from a second chamber, defined on the piston; a conduit connects the housing to the first chamber, which, in turn, is connected to the atmosphere through a conduit, a channel and a groove; a third chamber, separates from the first chamber, when the piston is in the first limit stop; ducts and a bistable valve are equipped with a double closing device, actuated by the element, to connect the chamber to the air d tube, so that, when the element is in the first configuration, the valve can reach the first position of Stability and the plunger can be found in the first limit stop, and vice versa, to connect the cameras to each other, and to join the chambers to the atmosphere through the conduit, the channel and the slot, when the element s is in the second configuration and, consequently, the valve reaches the second stability position; when the tire pressure falls below the previously set lower threshold value, the element immediately reached the second configuration to allow the bistable valve, equipped with a double lock device, to reach the second stability position and close the connection between the duct and the chamber, through the channel and the duct and to open the connection between the chamber and the housing, in turn, attached to the atmosphere, through the channel and the duct; in this condition, the plunger always moves to a second limit stop and, therefore, does not act on the core of the self-closing valve, which can maintain its function of preventing air from escaping from the "air tube" , without introducing the risk that the pressure of the tire continues to fall below the lower threshold value, when the same device presents a leak, this device also includes a resource used to indicate whether the tire pressure is correct or not.
2. 2. The device according to claim 1, wherein the element with variable geometric configuration is a bistable sheet.
3. 3. The device according to claim 1, in which the element with variable geometric configuration is a bimetal, which allows the change of the pressure threshold, which causes the change of the bending as a function of the temperature.
4. 4. The device according to claim 1, wherein the deformable sealing member consists of a bellows, which joins the threaded body to the plunger; this bellows allows frictional axial sliding of the plunger inside the device and separates two chambers, which are located respectively below and on the plunger.
5. 5. The device according to claim 1, wherein the upper part of the plunger is held by the housing closed by the element, with variable geometrical configuration; a package ensures sealing between the inner part of the housing and the chamber; a channel connects the housing to the internal ducts of the plunger, and the element with variable geometric configuration controls the channel acting on the bistable valve, equipped with a double closing device, the valve present a first stability position, when the first section of the valve closing device closes the connection between the housing and the channel, while maintaining the connection between the conduit and the open channel, and a second stability position, when a second section of the valve locking device closes the connection between the conduit and the channel, while maintaining the connection between the housing and the open channel.
6. 6. The device according to claims 1, 2 and 3, in which the element with a variable geometric configuration reaches the second geometric configuration, when the pressure in the chamber does not have a sufficiently high value with respect to the atmospheric pressure that exists in the housing; the bending of the element depends on the difference between the pressure in the bed, connected to the air tube of the rim, when the piston is in the first limit stop, and the pressure inside the housing, connected to the atmosphere; if this difference in pressure is sufficiently high, the element reaches the first geometric configuration with stability, vice versa, the element maintains its second geometric configuration.
7. 7. The device according to claim 1, wherein the external axial thrust causes the axial movement of the outer cover, with respect to the threaded body, by exceeding the thrust of the spring; this thrust on the external body of the device (outer sheath and wall) causes the change in the geometrical configuration of the element and the movement of the plunger towards the first limit stop, as it might happen, if the pressure in the chamber is sufficiently greater than the pressure in the housing and the camera; in this phase, the bending of the element and the movement of the plunger towards the first limit stop occur only due to the mechanical thrust.
8. 8. The device, according to claims 1 and 7, in which, after releasing the thrust, the spring and the air pressure, acting in the chamber, move the outer cover back to its original stable limit stop; if the air pressure of the rim, which exists in the chamber, is capable of exerting a tension on the element, this tension is sufficient to maintain the element in the first geometric configuration, the tension also keeps the piston held in the first stop limit, so the piston rod can keep the core of the self-closing valve open, to ensure the continuous connection between the air tube and the element through the chamber, and the cavities, where the tube pressure exists; therefore, as long as the pressure of the rim maintains a sufficient value, ie above at least one previously established threshold value, the device will remain charged, that is, with the element in its first geometric configuration and with the plunger in the first limit stop, to maintain the connection with the air tube of the rim through the self-closing valve core.
9. 9. The device according to claim 1, wherein the position of the plunger indicates whether or not exceeding at least one threshold value previously established; for this purpose, a transparent viewer, applied to the wall, which shows a chromatic change in the function of the plunger position is used.
10. 10. The device according to claim 9, in which the displacement of the plunger, or the change in the geometric configuration of the element, establishes in the work an electrical circuit by means of which the emission of the optical and / or acoustic signals can be obtained, to be transmitted by means of hertzian waves.