Resilient tires and wheels – Tires – resilient – Inflating devices
Reexamination Certificate
1999-02-18
2002-06-25
Stormer, Russell D. (Department: 3612)
Resilient tires and wheels
Tires, resilient
Inflating devices
C152S427000, C137S227000, C137S493800
Reexamination Certificate
active
06408913
ABSTRACT:
The present invention relates to a valve for inflating inner tubes for tyres (alternatively spelled “tires”), to an inner tube provided with said valve and to a wheel for vehicles comprising a tyre mounted on a corresponding rim and provided with said inner tube; more particularly, the invention relates to an inner tube formed by one or more separate compartments and provided with an inflation valve which does not have any fixed systems for connection to the outside of the tyre (alternatively spelled “tire”) and the rim.
The wheel is the element forming a link between vehicle and road; it performs the functions of providing the vehicle and its load with a pneumatic-type support system and ensuring, by means of the tyre, a suitable behaviour on the road.
Supporting of the vehicle is provided by the volume of pressurized air contained inside the wheel; for this purpose, the first and the most common of the solutions adopted consists in the use of an inner tube inserted between tyre and rim and inflated with pressurized air introduced into the tube by means of an inflation valve projecting outside the wheel.
More precisely, the wheel comprises a tyre defining a toroidal cavity which is mounted on a corresponding rim and has a bottom surface provided with a central channel and two bead seats on which the beads of the tyre rest in abutment and which are each axially delimited between an end radial surface (projecting shoulder) in an axially external position and an axially internal, annular, raised counter-surface.
The inner tube, inserted between tyre and rim, comprises a torus-shaped expandable tubular body which is generally made of elastomeric material and which can be inflated by means of an associated inflation valve. The valve usually comprises a base for connection to the inner tube and a cylindrical casing (stem) which is fixed to the base and inside which the mechanism for activating the inflating and deflating operations is arranged.
The stem of the valve is usually housed in a suitable hole which is provided on the bottom surface of the rim, more precisely on the channel wall, and from which it emerges into the external environment, at atmospheric pressure, with the corresponding end closed by a cap.
The aforementioned valve allows at least three fundamental operations to be carried out in order to provide the tyre with the correct operating pressure, i.e. inflation and rapid deflation and adjustment to the desired pressure value.
The traditional inner tubes, precisely on account of the fact that they comprise a stem passing through the rim, may pose problems—which are currently still unsolved—in some operating conditions of the tyre.
In fact, in conditions of rapid acceleration of the vehicle, it has been noted that the tyre may slip with respect to the rim with a consequent high risk of tearing of the tube at the bottom of the valve or shearing of the valve stem, which results in immediate deflation of the tyre and corresponding loss of stability of the vehicle, with serious risks as regards the safety of the driver and the passengers of the vehicle itself.
The problem is further accentuated in the case of high-performance tyres, but cannot be excluded in other applications, in particular in view of the fact that the present-day vehicles, even though they have a limited power, and hence are incapable of very high speeds, nevertheless allow high driving torques to be transmitted to the ground, so as to give rise to the aforementioned risks.
Essentially the problem of having an inner tube which is safe even in the case of slipping between the tyre and rim is still unsolved.
Moreover, it must be pointed out that the mounting of a traditional inner tube between tyre and rim involves a few problems since the inner tube must be inserted by passing it through the limited space defined between the side of the tyre and rim and then, by means of successive attempts at performing a manual operation which is not particularly easy, introducing the stem of the valve through the appropriate hole on the rim so that it emerges with its end portion into the environment outside the wheel, at atmospheric pressure. In particular, the aforementioned problem arises more frequently in so-called “low profile” tyres, where the ratio between the cross-sectional height, measured between the base of the beads and the top of the tread, and the maximum width of the tyre, is equal to or less than 0.7.
The Applicant has realized that there is the possibility of solving the problems according to the state of the art by adopting a flexible container, which may be an inner tube, having the characteristic feature that the valve or the valves necessary for inflating or deflating it do not have any element for connection to the external environment, passing through the rim.
In particular, the Applicant has realized that inflation of the tube could be performed by introducing pressurized air into the space between tyre and rim, so as to deform the tube with respect to its initial shape and thus create a difference in pressure between the internal volume of the tube and the external space and then waiting for the equilibrium between the pressures in the aforementioned environments to be re-established, corresponding to a return of the tube to its original undeformed configuration. Subsequently the air present outside the tube could be left to flow out into the surrounding environment, thus allowing expansion of the tube itself until it completely fills the cavity between tyre and rim.
Advantageously, the initial introduction of pressurized air into the aforementioned space would exert also a thrusting force useful for positioning the beads of the tyre in abutment on the corresponding seats of the rim, against the projecting shoulders, so as to form a preliminary sealed closure of the abovementioned space. According to the Applicant's idea, the correct and predetermined value of air pressure inside the tube would be reached by allowing the air which has an overpressure with respect to the desired value to flow out by means of a device which has been suitably adjusted to said value.
According to a first aspect thereof, the invention relates to a device for inflating and deflating a flexible container which is elastically expandable for the introduction of pressurized fluid into its internal volume and which can be housed in a cavity which can be isolated from an external environment, at atmospheric pressure, said device being inserted in a wall of said container, characterized in that it does not have elements for connecting the internal volume of said container and said external environment.
More particularly, the container is an inner tube for tyres and the cavity which can be isolated from the external environment includes the toroidal space defined by a tyre mounted on the corresponding mounting rim.
In a first embodiment thereof, the device according to the invention comprises three separate valves for separately performing the three operations fundamental for operation of the -tube, i.e. at least one first inlet valve for inflating the tube with pressurized fluid, at least one second adjustment valve for regulating and maintaining the pressure existing inside the tube within a predetermined range of values, and at least one third discharge valve for rapid deflation of the tube.
In a second embodiment of the device a single valve performs the two functions of adjustment and rapid deflation of the tube, the inflating function being assigned to a second valve.
In another preferred embodiment of the invention a single device performs all three required functions, i.e. it combines an inflation valve with a second valve for adjustment and rapid deflation of the tube.
In all the cited embodiments the function of rapid deflation of the tube may be advantageously performed by acting, from the outside, on the mechanism activating the valve so as to cause opening thereof, for example by means of remote interaction based on the creation of electric or electromagnetic fields or by means of remote commands with
Cantu′ Marco
Caretta Renato
Volpi Alessandro
Finnegan Henderson Farabow Garrett & Dunner LLP
Pirelli Pneumatici S.p.A.
Stormer Russell D.
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