Rotary shafts – gudgeons – housings – and flexible couplings for ro – Having lubricating means – For coupling having torque transmitted via intermeshing teeth
Reexamination Certificate
1995-01-24
2001-03-06
Walsh, Donald P. (Department: 3653)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Having lubricating means
For coupling having torque transmitted via intermeshing teeth
C464S159000
Reexamination Certificate
active
06196922
ABSTRACT:
The invention relates to a universal joint coupling according to the entering clause of claim
1
.
A universal joint of this kind has been known from EP 0 297 615 B1 the disclosure of which is expressly incorporated herein by reference. In some cases it has been found with universal joint couplings of the kind described therein that, following a disassembly and the subsequent re-assembly, the universal joint has but a short remaining service life. De-mounting and subsequently re-mounting the universal joint coupling may be required for instance in the course of maintenance work. The universal joint coupling of an eccentric worm pump, as a rule, has to be disassembled and subsequently re-assembled regularly when the rotor of the eccentric worm is exchanged.
In a printed publication of the “Institut für allgemeine Gestaltungslehre und Maschinenelemente der TH München” (Institute for general design and machine elements at the Technical University Munich) which dates back to 1957 and refers to experiences gained in the construction of machine elements, it is mentioned that whenever machined elements have to be assembled, a design engineer should ask himself whether a certain position of the elements relative to each other has to be defined. Said printed publication does not refer to universal joint couplings of the above-mentioned kind.
The object of the invention is to provide a universal joint coupling of the kind mentioned above whose service life is increased compared to prior art universal joint couplings under comparable operating conditions.
According to the present invention, said object is achieved with a universal joint coupling comprising the features set out in claim
1
. The invention is based on the finding that wear of a universal joint coupling of the above-mentioned kind can be particularly aggravated following a disassembly of the universal joint because the spherical cup(s) and the internal ring gear, as well as the internal ring gear and the hub normally occupy upon re-assembly a position with respect to each other differing from the positioning of the first assembly of the universal joint coupling. The position of the named parts which is different compared to the first positioning has as consequence that the universal joint coupling has to undergo a running-in again. However, if the connection in particular of the spherical cup being higher loaded during normal operation, on the one hand, and on the other hand the connection of the internal gear ring and the hub are designed such that, after a disassembly of the universal joint, the original positioning results automatically when the universal joint is assembled again, renewed running-in does no longer exist and the service life of the universal joint coupling is increased.
The clear and reliably reproducible positioning demanded according to the present invention of spherical cup(s) and internal gear ring, on the one hand, as well as on the other hand of internal gear ring and hub guarantees that the same spherical surfaces defined by the ball segments and spherical cups, respectively, always cooperate upon a re-assembly of the joint.
According to the invention, it has therefore been found that a decisive factor resides in designing the connection of the named parts such that, after disassembly of the joint, they can be re-assembled only such that they occupy their original positions.
According to one embodiment of the universal joint coupling according to the present invention, in which the lubricant passages are defined by omitting teeth of the torque transmitting pair of coupling members, for instance by omitting two teeth of the external toothing, and in which the grooves formed as lubricant passages have a depth less than the corresponding tooth depth, this is achieved in connection with the internal gear ring and the hub in that the torque transmitting pair of coupling members has an uneven number of teeth. In this manner it is guaranteed that the lubricant passages have an uneven circumferential spacing which permits the joining of external toothing and internal gear ring in only one position. If the torque transmitting pair of coupling members has an even number of teeth, the clear positioning of internal gear ring and hub can be achieved according to said embodiment in that the number of teeth located, as seen in clockwise direction, between the lubricant passages formed by the omission of counter-acting bodies, differs by at least two teeth from the number of teeth located, as seen in counterclockwise direction, between the lubricant passages. Contrary to the universal joint coupling known from EP 0 297 615 B1, the lubricant passages are thus not located substantially directly opposite each other, but are arranged so as to be offset by at least one tooth.
According to another embodiment of the universal joint coupling according to the present invention, the clearly reproducible position, or positioning, of internal gear ring and hub is achieved by an irregular pitch of the torque transmitting pair of coupling members. Said irregular pitch again has as consequence that the hub with the external toothing provided thereon and the internal gear ring can be assembled in only one position.
The clear position of at least the spherical cup being higher loaded during normal operation and of the internal gear ring with respect to each other is achieved according to an embodiment of the universal joint coupling according to the present invention by means of connecting the internal gear ring and the corresponding spherical cup by a material bond. The material bond between the corresponding spherical cup and the internal gear ring is preferably effected by an adhesive. The material bond can be obtained, however, also by brazing, welding, or by other connection techniques with which a material bond is achieved.
According to another embodiment of a universal joint coupling according to the present invention, the clear position of internal gear ring and spherical cup is effected by a non-positive connection of the named elements, which is achieved for instance by shrinking-on the internal gear ring to the end region of the corresponding spherical cup.
According to still another embodiment of the universal joint coupling according to the present invention, the clearly reproducible position of internal gear ring and at least the spherical cup being higher loaded during normal operation, with respect to each other, is achieved by at least two feather keys of different widths which are arranged in the housing and effect a positive connection between the spherical cup and the internal gear ring. The different widths of the at least two feather keys result in that the spherical cup and the internal gear ring can be joined in one single position only. Alternatively, this can be achieved also by at least two feather keys of same width which can be arranged in the housing and which have an uneven circumferential spacing. According to another alternative, the at least two feather keys may be arranged in the housing such that they have a common line of symmetry in a cross section normal to the longitudinal axis of the housing which is displaced in axis-parallel relation with respect to a straight line extending through the center of the universal joint coupling. The said arrangement as well permits joining of the spherical cup and internal gear ring in one single position only. The afore-mentioned arrangements and constructions, respectively, of feather keys may be combined, however this is not necessary to achieve a clear positioning of the corresponding spherical cup and the internal gear ring with respect to each other.
According to still another embodiment of the universal joint coupling according to the present invention, at least the spherical cup being higher loaded during normal operation is clearly reproducibly brought in a position with respect to the internal gear ring in that one of the closure members engages the associated recess extending radially through the internal gear ring, said recess being arranged suc
Franz Gunter
Hantschk Gunther
Maier Bernd
Baker & Botts L.L.P.
Netzsch Mohnopumpen GmbH
Rivera William A.
Walsh Donald P.
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