Joints and connections – With adjunctive protector – broken parts retainer – repair,... – Holding means or protector functioning only during...
Reexamination Certificate
1999-03-01
2001-01-23
Kim, Harry C. (Department: 3629)
Joints and connections
With adjunctive protector, broken parts retainer, repair,...
Holding means or protector functioning only during...
C403S404000, C074S339000, C192S053340
Reexamination Certificate
active
06176635
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a frictional coupling, especially a synchronization device of a gear mechanism, with at least two coupling bodies which come into contact during engagement of the coupling, wherein one coupling body consists of one ring-shaped base body of metal with, at least, one flat, conical or cylindrical carrier surface to which a frictional layer is attached, and at least one other coupling body of a counter body, preferably also made of metal, which has a counter surface which works together with the frictional layer.
2. The Prior Art
Frictional couplings as well as also synchronization devices of this type are already known in various embodiments from multiple sources. They have the object to create a frictional contact between structural parts rotating a different numbers of revolutions and, in such a way, to make the numbers of revolutions the same. Primarily, those types of frictional couplings are used mainly in motorized vehicles for the synchronization of gear mechanisms to facilitate their shifting and the gear change. Especially, conical frictional systems, prior to being put into operation, in installation and in the new condition of the surfaces brought into frictional contact, exhibit high frictional values during frictional contact which are due to the manufacturing condition of the surfaces of the frictional pairing and make the first shifting of the coupling disadvantageously difficult. If the coupling bodies to come into frictional contact with one another are pressed or hit against one another with a large force during transport prior to installation or during installation itself, there can even be clamping or damage to the edges, by which the first shifting movements can be seriously impaired or even made impossible. These disadvantages are only reduced or eliminated after several shifting procedures of the new coupling or of the new synchronization mechanism as soon as the surfaces of the frictional pairing coming into frictional contact are somewhat smoothened off and have come to fit to one another.
A frictional pairing with a thin, quickly-closing insertion layer on one of frictional bodies is described in DE-OS 2 264 275. This insertion layer, however, in an exothermal reaction is said to form conversion products that act like emery, whereas also binding agents can be used which burn or crack and, in so doing, leave carbon residues behind. In so doing, the counter frictional surface are said to be rapidly freed from all impurities and the desired surface quality quickly achieved. As is, however, mentioned later, the substances formed in the insertion process fall out as a strong expulsion substance, so that this solution is only sensible for use in open systems, for example, in brakes. In closed systems such as lubricated frictional couplings or synchronization devices running in an oil bath, this expulsion substance impurifies the lubricant or the oil and thus acts bothersome and functionally hindering by, for example, penetrating the bearing.
It is thus the object of the invention to further develop the known frictional couplings and synchronization devices with closed systems in such a way that the identified disadvantages of the known embodiments can be avoided through continuous uninhibited function and the operation in the new condition can be facilitated. Especially, the so-called green shiftability of the gear train in synchronization device should be improved.
SUMMARY OF THE INVENTION
The invention solves this problem in that a wear-material made of paraffin or wax is applied between the base body and the counter-body onto at least one part of the surface facing the other coupling body, which material, prior to starting to operate the frictional coupling, keeps the base body, especially the frictional layer, from being in contact with the counter-body and closes it for a short time in the first operation during the frictional contact between the coupling bodies through the appearing frictional forces and the generated temperature. The wear-material to be used according to the invention does not form any particle-shaped expulsion substance which could hinder the function of the bearing or even of the synchronization device and, after its removal, it can be dissolved from the coupling body or bodies completely into the oil or the lubricant, so that there is no fear of negative effects.
Wax exhibits, for example, high adhesion also on smooth surfaces such as steel and can be penetrated, which is advantageous especially for tight application onto sinter materials. Paraffin is similar. Wax and paraffin are also wettable and have a low heat conductivity. Both materials effect, for a limited time, a reduction of the frictional number in the frictional contact, so that, in a simple manner, the frictional number-reducing effect of the applied wear-materials with the reduction of the frictional number in the frictional contacts can be adjusted to the desired operational level.
The coupling bodies coming into frictional contact in the switching-on of the coupling are kept apart by the wear-material arranged between them already during transport and during the installation of the coupling, so that they are not clamped or damaged at the edges, even if they are pressed or hit against one another. Also in the initial operation of the frictional coupling, the frictional surfaces of the coupling bodies are, at first, for a short time, kept out of frictional contact, for the purpose of which the wear-material preferably has a height or thickness which is sufficient to keep the coupling bodies safely apart over their entire circumference. They only slowly come gradual contact upon gradual wearing-out of the wear-material, upon which the larger areas of the unevenness of the surfaces from the manufacturing are smoothened. The so-called green shiftability of a new frictional coupling or of a new synchronization mechanism is thereby substantially facilitated. After a series of shifting processes, the wear-material is entirely eliminated and the frictional surfaces are smoothened to the extent that smooth usage and the normal operation of the frictional coupling is ensured.
In a further embodiment of the invention, the melting point of the wear-material is lower than the melting point of the material of coupling bodies coming into frictional contact, especially of the frictional material and the phase change of the wear-material from solid to liquid lies within the temperature range which appears in the demand on the used frictional pair, wherein the wear-material melts away due to the appearing frictional temperature.
According to the invention, however, also the shearing strength of the wear-material can be smaller than the shearing strength of the material of the coupling bodies coming into frictional contact, especially of the used frictional material, wherein the wear-material is sheared off upon demand placed on the used frictional pairs through the appearing frictional forces. In both cases, a relatively rapid elimination of the wear-material is guaranteed, so that the frictional surfaces of the coupling bodies grip one another completely.
Appropriately, the wear-material has a low heat conductivity. These wear-resistance materials can be advantageously applied onto all frictional materials and also onto the rest of the surfaces of the coupling bodies, especially onto the counter-surface working together with the frictional layer.
The frictional layer applied onto the carrier surface of the base body can consist of sprinkling sinter material. The advantageous frictional characteristics of the material are known; besides this, the sprinkling sinter material has, due to its porosity, a special suitability for application of a wear-material, especially of paraffin or wax. It is, however, also possible to use a frictional layer which consists entirely or partially of organic material and, in all cases, with a resin-binding agent. Equally suitable is a frictional layer made of spurted-up metal su
Dykema Gossett PLLC
Hoerbiger Antriebstechnik GmbH
Kim Harry C.
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