Spoked wheel for tubeless tyres and construction method thereof

The present invention relates to the spoked wheels which are normally used to lend greater elasticity to the vehicle, as well as a more elegant appearance.

Spoked wheels are usually mounted by making a hole at the two fixing points, that is both in the rim and in the hub. This type of construction therefore obliges the user of spoked wheels to adopt tyres with inner tubes. Nowadays, however, there is an ever-increasing preference for tubeless tyres, which have several advantages over those with inner tubes.

. US-A-4.275.931 is known which provides a steel rim in two parts, one for carrying out the seal with the tubeless tyre and the other for fixing the spokes. In this case, the centering of the wheel must be manually carried out by selectively pulling the spokes; this involves costs due to the labour which must be carried out by a very skilled person and unreliable final precision due to the fact that this individual capacity of the worker. However, in any case, it is impossible to reach a precision better than 0,5 mm.

With this embodiment, since a part is fixed to the other by means of welding, the possible replacement of a spoke involves the complete disassembling of the wheel or making a hole in the airtight part in order to replace the nipples. In this latter case, the wheel is no longer airtight therefore the tubeless tyre must be replaced with a normal tube tyre.

Furthermore DE-A-3.028.827 is also known. It describes a spoked wheel carried out in two parts which are assembled one with the other. However, the seal is obtained by means of a gasket positioned between both parts. It is as time passes subject to wear due to the vibration of the tyre and the heat which develops during use. If one of the spokes breaks in order to replace it the whole wheel must be disassembled including the tyre and the two parts forming the rim will have to be divided. Therefore, this work takes a long time and is expensive.

The object of the present invention is to provide a spoked wheel for tubeless tyres the assembling of which is simple, fast and perfect; its seal lasts for a long time and is secure and the possible replacement of a spoke can be done without disassembling the wheel.

The aforementioned purpose has been achieved by designing a rim split into two matching parts, one of which is continuous and can therefore carry out the seal, while the other is such that it can accommodate the seats for the spokes both parts are in aluminium and have a coupling device and reciprocal locking device.

In a preferred embodiment, furthermore, the coupling device is formed of a groove and a tooth which are inserted one in the other.

A further preferred embodiment provides that the locking device is formed of holes facing each other inside which a screw penetrates that is locked by a nut.

The construction method of the wheel of this invention foresees that the spokes between the hub and the inner part are mounted by pulling them in a uniform way, then the areas of the two parts which will be joined together are machined and the two parts are joined and fixed forming the finished wheel. In this way, the manual centering of the wheel is eliminated, a much higher precision is obtained better than the one that can be obtained with another construction or other processes.

The present invention will now be described on the basis of an exemplary embodiment which is illustrated in the attached drawings, in which:

• Fig. 1 shows an exploded sectional view of the proposed wheel;
• Fig. 2 also shows a sectional view, but of a mounted wheel.

With reference to the drawings it will be noted that the proposed wheel comprises a hub 10 which is such that it can be locked onto the studs 11 which enter holes 12 in the hub and are fixed by bolts 13. The hub construction is of a conventional type.

The rim, indicated as a whole by 20, comprises two parts: an outer part marked 21 which bears the seats 22 for the tubeless tyre. The whole surface of part 2l is perfectly unbroken and airtight; it is provided only with a hole 23 for the valve. This part 21 can thus carry out a perfect seal with the tubeless tyre which is not shown.

Part 21 of the rim is furthermore provided with a coupling device, consisting for example of a circular groove 24 and a locking device consisting for example of a threaded hole 25.

The inner part 26 of the rim is provided with a matching coupling device (for example a tooth 27) which fits into the coupling device 24 and a matching locking device 28 mating with the locking device 25 into which a bolt 29 fixed by a nut 30 can be inserted. Onto this second part 26 are fixed the spokes R which, as it is known, are mounted using holes 31 and 32 which are made in the second part 26 of the rim and in the hub 10 respectively.

Assembly of this wheel is accomplished by simply mounting all the spokes R between the hub 10 and part 26 of the rim pulling them in a uniform way, machining the two parts: the inner part 26 and the outer part 21 in correspondence with the reciprocal coupling areas, then the screws 29 are inserted into the threaded holes 25, then part 26 is mounted inside part 21 of the rim, making the matching piece 27 fit into the coupling device 24 and the screws 29 into the holes 28, after which the nuts 30 are tightened. The wheel thus mounted can accommodate a tubeless tyre. It is very precise as regards the eccentricity and skidding. In particular, it reaches an accuracy that can be compared to the one of the alluminium alloy wheels without spokes.