Air-liquid valves for off-the-road vehicle tires

A valve structure for heavy duty applications in connection with off-the-road or agricultural vehicle tires. Such applications involve a substantial increase in the weight of tires so that the vehicles will acquire stability in maneuvering; e.g. in the case of muddy, rocky, hilly conditions or the like.

BACKGROUND, OBJECT AND SUMMARY OF THE INVENTION 
The present invention pertains to valves useful in heavy construction 
application, and more particularly, to valves that are to be used on tubes 
disposed in off-the-road or agricultural vehicle tires. 
It has been known to employ for a variety of purposes valves having stems 
formed of molded rubber. Such devices commonly include embedded metal 
inserts inside of which a valve core is contained or housed. In order to 
provide background material for a consideration of the present invention, 
reference may be made to U.S. Pat. No. 2,652,067 in which a valve useful 
in connection with tubes of automobile tires is disclosed, such valve 
having the aforenoted molded rubber stem and further including an embedded 
insert and a valve core within said insert. However, the valve structure 
disclosed in that patent includes a constriction in its bore in the form 
of an internal resilient annular shoulder which functions to provide the 
requisite valve seat, or alternately, a stop for a valve core abutment. In 
either case, such configuration involves a restriction in the pathway 
provided by the bore. Therefore, such a construction is totally 
inappropriate in the case of a valve which is required to pass a liquid 
flow, in which case a substantially smooth and continuously wide diameter 
bore is essential. 
A valve stem formed of molded rubber that has been known before, and which 
is adapted for use in connection with heavy duty applications, that is to 
say, off-the-road applications involving operation on rough terrain such 
as hills, muddy and rocky locations and the like, is that shown 
hereinafter in FIG. 1 of the drawing. Such a molded valve includes a 
commonly used short or stub-valve core, chiefly for the reason that such 
valve core is easier to make and hence less expensive. 
A further feature of the known valve device is that interlocking engagement 
between the valve insert and the molded rubber body is accomplished by 
reason of rubber material being forced in the molding operation into a 
groove at the lower end of the valve insert. This will become apparent as 
the description of the known device proceeds. 
The fundamental difficulty that has been encountered in the use of the 
known heavy duty valve device results from the fact that in order to 
increase the weight of the previously noted vehicles utilized in heavy 
duty work on rough terrain, it is customary to add a clacium 
chloride-water solution to the tire tubes in addition to the requisite 
amount of air. Of course, it will be appreciated that the calcium chloride 
is employed in order to prevent the water from freezing under adverse 
conditions. 
It has been discovered that with the current design, that is to say, with 
the currently used heavy duty valves, liquid splashes onto exposed 
portions of the valve insert, causing the end of the insert to corrode and 
thereby allowing the vulcanized bond between the rubber and the metal 
insert to be broken with consequent loss of air from the tube, and 
resultant damage to the tire. 
Accordingly, it is a primary object of the present invention to overcome 
the aforesaid problem relating to corrosion of a valve insert in a heavy 
duty valve environment in which a liquid present in the tube is the source 
of the problem. 
Another object is precisely to eliminate the problem defined so as to avoid 
expensive flat tire repairs on vehicles of the type described. 
Another object is to overcome the problem without resorting to any 
techniques or methods which would result in hampering the flow of the 
required liquid into the tubes with which the valves are used. 
Yet another object is to accomplish or effectuate the solution explained 
above but to do so with a minimum of expense involved in providing rubber 
at the interior of the valve bore. 
A still further object is to accomplish the aforenoted solution so as to 
eliminate the corrosion problem and yet to maintain the interlocking 
engagement between the bonded rubber and the valve insert. 
The above-noted objects, as well as others, are fulfilled by a primary 
feature of the invention according to which the lower end of the molded 
rubber valve is formed so as to have a hook-like annular projection at its 
end and the rubber is molded around this hook-like portion whereby the 
necessary locking or interengaging relationship is established in a bonded 
fashion between the metal of the insert and the rubber. Moreover, the 
rubber is molded at the interior portion in such a way as to define the 
bore so that the diameter of the bore at its exit end is at least as great 
as the diameter for the bore defined throughout the metal insert. In other 
words, the molded rubber at the interior does not act in any constricting 
way to impede the flow of liquid through the bore, and as aforenoted, the 
diameter of the bore defined by the rubber is no less than the diameter 
which prevails throughout the major extent of the interior of the metal 
insert, that is, the inner periphery or bore as defined by the metal 
insert. 
Other and further objects, advantages and features of the present invention 
will be understood by reference to the following specification in 
conjunction with the annexed drawing, wherein like parts have been given 
like numbers.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the figures of the drawing, there will be seen in FIG. 1 a 
known valve device for heavy duty applications involving the use of such 
device in connection with a rubber tube or the like that is to be filled 
with both air and liquid. Specifically, the liquid would be a 
water-calcium chloride solution. The use of such a solution insures that 
the tubes will be sufficiently loaded that the vehicle will be able to 
maneuver in a stable manner over rough and difficult terrain; in other 
words, the context is one where although the vehicle may be used 
occasionally on pavement, it will generally be subjected to rough usage 
over hilly, muddy, or rocky terrain. 
In the known valve construction, it will be seen that a rubber body 10 has 
a tubular stem portion 12 and integral therewith a flange or base member 
14, the flange serving for mounting the device to the tube of a heavy duty 
vehicle tire. The body 10 is preferably molded of resilient rubber or the 
like by the use of conventional molding techniques. A tubular metal insert 
16 has an internally and externally threaded top portion 18 and a main or 
body portion 20 disposed within the molded rubber stem portion 12. 
The upper part 20A of the body portion 20 is suitably tapered so as to 
effectuate the requisite static seal at its inner periphery or bore 21. 
This seal is produced by contact of a gasket 22, included as part of the 
stub or short valve core 24, with the tapered portion. The valve core 24 
has a conventional cup-shaped member 26 which includes a rubber washer or 
grommet bearing against the lower end of the barrel of such core 24 to 
provide the required dynamic seal. 
Because of the heavy duty application for this valve structure, the 
construction of the main or body portion 20 is generally tubular with a 
fairly constant outside diameter. However, the thickness of the wall is 
somewhat greater at the upper and lower parts 20A and 20B. It should be 
especially noted, however, that a relatively lesser thickness, hence a 
larger internal diameter for the bore 21, is provided for the most part, 
so as to permit free flow of the liquid which is to be injected or flowed 
into the tube to which the valve device is attached. Thus, there is an 
extended fixed internal diameter for the bore 21 substantially throughout 
its length from the point at which liquid enters the bore to the point at 
which it exits. 
It will be seen at the inner termination of the valve insert 16 that a 
suitable groove 29 is provided such that when the molding operation is 
performed, rubber will be forced into the groove, thereby to bring about a 
firm locking engagement of the rubber with the insert. 
Despite the benefits which attend the application of the valve device 
depicted in FIG. 1, it has been discovered that corrosion does take place 
in the case of a water-calcium chloride solution for heavy duty 
applications. Accordingly, the improvement of the present invention 
provides a solution to that problem while retaining the advantages of the 
previous construction. Thus, as will be seen in FIG. 2, the essential 
valve construction previously noted in FIG. 1 is provided, except that at 
the lower or inner end of the valve the insert 16 is so formd as to have a 
hook-like annular projection 30 such that when rubber is molded around 
this hook-like portion to an appropriate extent, the necessary locking or 
interengaging relationship is firmly established between insert and the 
bonded rubber. However, the required wide diameter for the bore is not 
diminished in any way such that liquid can flow freely through the entire 
bore and into the tire tube. 
The hook-like annular portion extends downwardly from a point close to the 
center line of the slightly thickened wall portion 20B and extends 
outwardly from the valve axis as the portion 30 reaches its termination. 
In the molding process the rubber is so molded so as to extend up to the 
slightly thickened wall portion 20B. Accordingly, the rubber portion 32 
located inwardly of the hook-like portion 30 serves to define the inner 
end of bore 21, such rubber portion 32 having a diameter at least as large 
as the upper part of bore 21; that is to say, the upper part which extends 
between the thickened portions 20A and 20B. Also by this particular 
arrangement, the end of the insert 6 is protected; thus it is ensured that 
any normal splashing of the water-calcium chloride solution contained in 
the tire tube will not produce corrosion of the insert and thereby affect 
the bonding between the rubber and insert 16 at its inner end, as was the 
case noted with the valve device of FIG. 1. 
While there has been shown and described what is considered at present to 
be the preferred embodiment of the present invention, it will be 
appreciated by those skilled in the art that modifications of such 
embodiment may be made. It is therefore desired that the invention not be 
limited to this embodiment, and it is intended to cover in the appended 
claims all such modifications as fall within the true spirit and scope of 
the invention.