Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Nonmetallic element
Reexamination Certificate
1998-10-21
2001-01-30
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Nonmetallic element
C464S095000, C464S153000
Reexamination Certificate
active
06179716
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a shaft coupling transmitting rotating driving force between two shafts, whose centers are slightly deviated from each other, and more concretely to a kind of catch plate couplings, in which two shafts are disposed, adjacent to each other, with phases shifted by 90° from each other so that rotational movement can be continuously transmitted, independently from forward or backward rotation.
DESCRIPTION OF THE PRIOR ART
As a fundamental mechanism of this kind of eccentric shaft couplings there is known an Oldham coupling
100
as indicated by an exploded perspective view in FIG.
9
. This coupling
100
is a kind of flexible couplings for coupling two shafts
101
and
102
, whose centers are slightly deviated from each other, and in which there is disposed a buffer
103
for removing unnatural power transmission between the two shafts
101
and
102
. A boss
108
or
109
, in which a groove
106
or
107
is formed, is mounted on an extremity of each of the shafts. Rectangular protrusions
110
and
111
protruding from surfaces of an intermediate disk
112
opposite to each other, which rectangular protrusions are long in directions perpendicular to each other, are engaged with the two bosses
108
and
109
, respectively. The two shafts
101
and
102
, whose centers are deviated from each other, can be fitted to the rotation transmission owing to the fact that a degree of freedom in the two directions is given to the buffer
103
as described above.
However, since the two shafts
101
and
102
should be kept separate from each other by a distance in order that the intermediate disk
112
can be put therebetween, this kind of couplings can not be used with a device having no spatial margin. Further, particularly in case where the rotational movement should be transmitted continuously, since it gives rise to mutual slide without interruption, the intermediate disk
112
is subjected to significant wear. Therefore, as indicated by an exploded perspective view in
FIG. 10
, grooves
124
and
125
engaged with protrusions
122
and
123
disposed on bosses
120
and
121
, respectively, are formed on two end surfaces of an intermediate disk
126
in an orthogonal relationship and at the same time a through hole
127
, in which extremities of the two shafts are accommodated at a central part, is formed so that a small distance between the two shafts can be dealt with. A carbon fiber reinforced plastic material having a good sliding property and a high resistance to wear is used for the intermediate disk
126
. In this example, when torque to be transmitted is great, fatigue due to repeated tensile and compressive stress produces cracks C in the intermediate disk
126
, which is deformed and finally destroyed, so that transmission of the torque becomes impossible.
SUMMARY OF THE INVENTION
An object of the invention is to provide an eccentric shaft coupling having a high durability and a small size, corresponding to closely disposed shafts, capable of transmitting correctly rotational movement in either of forward and backward directions and transmitting significant torque.
In order to achieve the above object, in an eccentric shaft coupling according to the present invention, cylindrical boss flanges, each of which is secured to each of extremities opposite to each other of two rotating shafts disposed so as to be adjacent to each other in series in a same direction.
On a surface of each of these cylindrical boss flanges, which is opposite to a corresponding surface of the other, a pair of protrusions having a same length provided with two parallel surfaces separated by a distance equal for the two protrusions extend along a diametral line from positions opposite to each other in an outer peripheral portion towards a center. The shaft coupling transmitting rotation of one rotating shaft to the other rotating shaft is constructed by coupling these two cylindrical boss flanges through an intermediate disk, in outer peripheral portions of which there are formed two pairs of rectilinear grooves in an orthogonal relationship which are engaged with the protrusions opposite thereto.
These rectilinear grooves formed in the outer peripheral portions of the intermediate disk consist of four cylindrical cavities. These cavities are at a same distance from the center on two diametral lines in an orthogonal relationship, and plane portions of two liners for each of cylindrical cavities, each having a partial cylindrical shape, whose cross section is enclosed by an arc and a secant. The protrusions are inserted into the cylindrical cavities on both the sides opposite to each other along arc-shaped inner walls forming each of the cylindrical cavities. Each of the grooves holds slidably the two parallel surfaces of each of the protrusions.
Further the intermediate disk is made of a metal having a certain rigidity. The liners, each having a partial cylindrical shape, whose cross section is enclosed by an arc and a secant, are made of a material having a high resistance to wear and a good lubricant property. In addition, spacers made of synthetic resin are put between surfaces opposite to each other of each of the cylindrical boss flanges and the intermediate disk in order to prevent that the two surfaces opposite to each other of each of the cylindrical boss flanges and the intermediate disk do not collide directly with each other in contact. Moreover it is preferable that the cylindrical boss flanges are sintered products made by powder metallurgy and that further finished size is decided by high pressure press rectification type sizing.
More preferably the two liners, each having a partial cylindrical shape, whose cross section is enclosed by an arc and a secant, are formed in one body made of a synthetic resin, in which they are linked by a thin plate-shaped portion at one edge of each of them; the length thereof in the axial direction is slightly greater than the length of the intermediate disk in the axial direction; and in addition the thin plate-shaped portion has an elastic and expansible construction, which energizes the two liners, each having a partial cylindrical shape, whose cross section is enclosed by an arc and a secant, so as to increase the distance therebetween.
REFERENCES:
patent: 1350011 (1920-08-01), Du Bois
patent: 1417432 (1922-05-01), Walker
patent: 1842582 (1932-01-01), Bulley
patent: 1887081 (1932-11-01), Buettell
patent: 2109935 (1938-03-01), Thomas
patent: 2295003 (1942-09-01), Natkins
patent: 2301660 (1942-11-01), Ricefield
patent: 3438221 (1969-04-01), Paulsen
patent: 3830081 (1974-08-01), Weber et al.
patent: 4121438 (1978-10-01), McCullough
patent: 4191032 (1980-03-01), August
patent: 4472156 (1984-09-01), Kryscyk
patent: 4838511 (1989-06-01), Terada et al.
patent: 4899608 (1990-02-01), Knappe et al.
patent: 27 35 664 (1978-03-01), None
patent: 307 564 (1929-03-01), None
Patent Abstracts of Japan. vol. 008, No. 238; JP 59-117917, published Jul. 7, 1984 (Kawada Yasuyuki)—(1 Page).
Asa Electronic Industry Co., Ltd.
Browne Lynne H.
Flynn ,Thiel, Boutell & Tanis, P.C.
Thompson Kenneth
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