U.S. patent number 3,641,479 [Application Number 04/833,614] was granted by the patent office on 1972-02-08 for underwater disconnectible connector.
This patent grant is currently assigned to D. G. O'Brien, Inc.. Invention is credited to Donald G. O'Brien, Edward R. Walker.
United States Patent |
3,641,479 |
O'Brien , et al. |
February 8, 1972 |
UNDERWATER DISCONNECTIBLE CONNECTOR
Abstract
An electrical connector of the plug and socket type for use in
an electrically conductive environment such as under water. The
plug is cylindrical in shape and carries a number of axially spaced
contactor bands which are exposed at and in flush relation to the
cylindrical surface. The socket, which is of greater diameter than
the plug, has an equal number of axially spaced annular contacts
which protrude inwardly into the socket to engage the contactor
bands of the inserted plug. Each connected pair of contacts is
isolated and sealed from the other connected contacts and from the
surrounding environment by resilient O-rings supported in the
socket and axially spaced in alternating arrangement with the
socket contacts. Insertion of the plug causes the O-rings to be
compressed radially between the cylindrical surface of the plug and
the internal surface of the socket.
Inventors: |
O'Brien; Donald G. (Framingham,
MA), Walker; Edward R. (South Natick, MA) |
Assignee: |
D. G. O'Brien, Inc.
(Framingham, MA)
|
Family
ID: |
25264870 |
Appl.
No.: |
04/833,614 |
Filed: |
June 16, 1969 |
Current U.S.
Class: |
439/277;
439/669 |
Current CPC
Class: |
H01R
13/523 (20130101) |
Current International
Class: |
H01R
13/523 (20060101); H01r 013/54 () |
Field of
Search: |
;339/8,94,182,183 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Claims
Having described our invention, what we claim is:
1. A fluidproof electrical connector comprising:
A. a tubular plug of electrically insulating material having at
least one electrically conductive plug contact thereon, at least a
portion of said plug contact being exposed at the tubular surface
of said plug;
B. an electrically insulating socket having a tubular bore of
substantially similar cross-sectional shape to that of said plug
tubular surface, said bore being of greater cross-sectional
dimensions than said plug so that when said plug is inserted into
said socket, a clearance exists therebetween;
C. at least one resilient, outwardly yieldable, electrically
conductive socket contact disposed within said socket and
protruding inwardly into said bore to present a yieldable
restriction to insertion of said plug into said bore;
D. said socket contact being positioned within said socket to be in
longitudinal alignment with, and thereby in resiliently engaged
contact with, said plug contact when said plug is fully inserted
into said socket;
E. a pair of inner perimetric grooves recessing said tubular bore
of said socket, with one of said grooves being on either side of
said socket contact,
F. at least one resilient sealing ring seated in each said socket
groove, each sealing ring having an inner opening of smaller
dimension than the cross section of said plug tubular surface,
whereby when said plug is fully inserted into said socket, said
sealing rings effect a sealed isolation of said electrically
connected contacts therebetween, and
G. a nonconductive, water-insoluble, greaselike material disposed
in portions of said grooves unoccupied by said sealing rings.
2. A fluidproof electrical connector comprising:
A. a tubular plug of electrically insulating material having at
least one electrically conductive plug contact thereon, at least a
portion of said plug contact being exposed at the tubular surface
of said plug;
B. an electrically insulating socket having a tubular bore of
substantially similar cross-sectional shape to that of said plug
tubular surface, said bore being of greater cross-sectional
dimensions than said plug so that a clearance exists therebetween
when said plug is inserted into said socket, said socket bore
having a circumferential slot in the surface of said tubular
bore;
C. at least one resilient, outwardly yieldable, electrically
conductive socket contact disposed within said socket slot and
protruding inwardly into said bore to present a yieldable
restriction to insertion of said plug into said bore;
D. said socket contact being positioned within said socket to be in
longitudinal alignment with, and in resiliently engaged electrical
contact with, said plug contact when said plug is fully inserted
into said socket;
E. at least one resilient sealing ring disposed within said socket
bore on each side of said socket contact, each sealing ring having
an inner opening of smaller dimension than the cross section of
said plug whereby when said plug is fully inserted into said
socket, said sealing rings effect a sealed isolation of said
electrically connected contacts therebetween, and
F. a nonconductive, water-insoluble, greaselike material contained
within those portions of said slot unoccupied by said socket
contact and precluding entrapment of a fluid conductor within said
slot.
3. A fluidproof electrical connector comprising:
A. a tubular electrical plug having electrical insulating material
seating at least one electrically conductive plug contact thereon
with at least a portion of said plug contact exposed at the plug
outer tubular surface and with said insulating material exposed at
the plug outer tubular surface on either side of said plug
contact,
B. an electrical socket having a tubular bore of substantially
similar cross-sectional shape to that of said plug outer surface,
said bore being of greater cross-sectional size than said plug so
that a clearance exists therebetween when said plug is mated with
said socket,
C. said socket carrying electrical insulating material for
supporting a contact thereon,
D. at least one electrical socket contact carried on said socket
seated in said bore on said insulating material thereon, said
socket contact being positioned on said socket to be in
longitudinal alignment with said plug contact when said plug is
matingly engaged with said socket, and said socket contact having a
resiliently and radially yielding contact surface protruding
inwardly into said bore for resiliently engaging, and maintaining
electrical contact with, said plug contact when said plug and
socket are matingly engaged,
E. said socket bore further having at least first and second
seal-carrying means, with one said means on either side of said
socket contact, and
F. at least first and second resilient annular sealing means
carried on said socket by said same-numbered seating means, each
sealing means having an inner opening constrictionally engaging
said insulating material exposed at said plug tubular surface on
the corresponding side of said plug contact when said plug is
matingly engaged with said socket, and said pair of sealing means
effecting a fluidtight seal across said clearance between said
matingly engaged plug and socket on either side of said engaged
contacts, and insulating with said seals the engagement of said
contacts from fluids in said clearance outwardly beyond said
sealing means from said contacts.
4. A connector as defined in claim 3 wherein said exposed portion
of said plug contact is free of outward projection beyond the
tubular plug surface that engages at least said one sealing means
more proximal to the opening into said bore.
5. A connector as defined in claim 3 further comprising a resilient
annular wiping member carried on said socket adjacent the
plug-receiving end of the bore therein, said wiping member
interferingly engaging the outer tubular surface of said plug for
wiping said plug surface upon mating interconnection of said plug
and socket.
6. A connector as defined in claim 3 wherein each said
seal-carrying means includes a perimetric groove recessing said
tubular bore of said socket.
7. A connector as defined in claim 6 wherein
A. each said groove has a width along the tubular bore greater than
the depth with which it recesses said bore, and
B. each said sealing means is an annular member which has, when
said socket is disengaged from said plug, a normal width along said
tubular bore and a normal thickness transverse to that width, both
of which are both less than the width of the groove in which the
member is seated and greater than the depth of that groove.
8. A connector as defined in claim 6 further comprising an
electrically nonconductive and water insoluble greaselike material
disposed in each said groove and filling the portions therein not
occupied by said sealing means.
9. A connector as defined in claim 6 in which said socket has a
further perimetric groovelike slot recessing the tubular bore
thereof and seating said socket contact.
10. In an electrical connector having a tubular plug carrying a
pair of first and second electrical plug contacts spaced apart
along the tubular surface thereof, and having a receptacle having a
tubular bore therein for receiving said plug in mating engagement
spaced inwardly therefrom and having a pair of first and second
electrical receptacle contacts, each for mating electrical contact
with said same-numbered plug contact, the improvement
comprising:
A. first, second and third annular sealing means carried on said
receptacle within said bore therein with one said sealing means
intermediate said receptacle contacts and each other sealing means
on an opposite side of said pair of receptacle contact, each said
sealing means resiliently compressively engaging said plug and
effecting a fluid-type seal between said matingly engaged plug and
receptacle on either side of said engaged first contacts and on
either side of said engaged second contacts, thereby isolating the
engagement of each of said same-numbered contacts from fluids in
the plug-to-bore space and outwardly beyond said sealing means from
each of said matingly engaged first contacts and second
contacts.
11. An electrical connector as defined in claim 10 further
comprising means forming a venting aperture through said receptacle
from the inner-end of said bore for venting fluid to the exterior
of said receptacle from within said bore during the engagement of
said plug thereinto.
12. In an electrical connector as defined in claim 10, the further
improvement wherein:
A. each of said sealing means includes at least one O-ring-like
member seated on said receptacle in a circumferential groove
recessing the bore thereof.
13. An electrical connector as defined in claim 12 further
comprising electrically insulating and water-insoluble greaselike
material disposed in said each groove in the spaces therein not
occupied by said O-ring means.
14. A fluidproof electrical connector comprising:
A. a tubular electrical plug having electrical insulating material
seating at least one electrically conductive plug contact thereon
with at least a portion of said plug contact exposed at the plug
outer tubular surface,
B. an electrical socket having a tubular bore of substantially
similar cross-sectional shape to that of said plug outer surface,
said bore being of greater cross-sectional size than said plug so
that a clearance exists therebetween when said plug is mated with
said socket,
C. said socket carrying electrical insulating material for
supporting a contact thereon,
D. at least one electrical socket contact carried on said socket
seated in said bore on said insulating material thereon, said
socket contact being positioned on said socket to be in
longitudinal alignment with said plug contact when said plug is
matingly engaged with said socket, and said socket contact having a
resiliently and radially yielding contact surface protruding
inwardly into said bore for resiliently engaging, and maintaining
electrical contact with, said plug contact when said plug and
socket are matingly engaged,
E. said socket bore further having at least first and second
seal-carrying means, with one said means on either side of said
contact, and having an aperture leading from the inner end of said
bore to outside said socket, and
F. at least first and second resilient annular sealing means
carried on said socket by said same-numbered seating means, each
sealing means having an inner opening constrictionally engaging
said plug tubular surface on the corresponding side of said plug
contact when said plug is matingly engaged with said socket, and
said pair of sealing means effecting a fluidtight seal across said
clearance between said matingly engaged plug and socket on either
side of said engaged contacts, and insulating with said seals the
engagement of said contacts from fluids in said clearance outwardly
beyond said sealing means from said contacts.
Description
SUMMARY OF THE INVENTION
Our invention is directed to an electrical connector particularly
suited for use in an electrically conductive, fluid environment
such as sea water.
The underwater effectiveness of our connector makes it quite
valuable in the rapidly expanding technology of marine research and
oceanography. For example, sonar transducers are frequently secured
to the outside of a submersible or underwater vehicle and are
connected electrically to circuitry located within the hull. When
replacing or repairing the transducer, it often is necessary to
drydock the entire vehicle. Out connector enables such a transducer
to be replaced by an underwater diver thereby minimizing the
expense and delay of drydocking. The diver need only disassemble
the connector, remove the transducer, replace it and reassemble the
connector.
In accordance with the invention, the connector includes a plug
formed from an electrically insulating material such as, for
example, a suitable glass ceramic or plastic material including
epoxy resins. One or more contactor bands or plug contacts are
embedded in the plug intermediate its ends and are exposed
circumferentially at the cylindrical surface of the plug. The
exposed portions of each of the plug contacts are spaced
longitudinally of the plug and, in the preferred embodiment of my
invention, are in flush relation with the plug to define a
contiguous and flush cylindrical plug surface. The socket into
which the plug is inserted is of greater cross-sectional diameter
than that of the plug so that a clearance may exist between the
assembled plug and socket. One or more annular socket contacts are
disposed within and extend inwardly into the socket; upon insertion
of the plug each socket contact is resiliently urged inwardly to
press firmly and continually against the cylindrical surface of the
plug. A socket contact is provided for each of the plug contacts;
the socket contacts are spaced longitudinally within the socket to
correspond to the longitudinal spacing of the plug contacts; thus,
when the plug is inserted fully into the socket, each plug contact
will be electrically connected with and firmly gripped by its
associated socket contact. O-rings are located so as to isolate
each socket contact and are supported within the socket to embrace
longitudinally each of the socket contacts. The inner diameter of
each O-ring is smaller than the cross-sectional diameter of the
plug. Thus, when the plug is inserted into the socket, the plug
radially compresses the resilient O-rings which then provide a seal
effective to isolate each set of mating plug and socket contacts
from each other and from the surrounding environment.
As the plug is inserted into the socket the restriction presented
by the inner diameter of the O-rings will cause the cylindrical
surface of the plug to be wiped free of dirt or water. An
additional O-ring may be provided at the socket entrance further to
enhance this wiping action.
The prior art suggests that an underwater connector of the plug and
socket type be constructed so that the plug is of equal or greater
diameter than that of the socket to enable them to be mated with a
snug, interference fit. By providing such an interference fit to
wipe and seal the contacts, repeated use of the connector may cause
the plug and socket surfaces to wear or deform. As the surfaces
become worn or deformed, the sealing and wiping characteristics of
the connector become less effective. When this occurs in a
connector of the type described in the prior art, the complete plug
and socket unit must be replaced. In the connector of my invention,
should the O-rings become worn or otherwise ineffective in
performing their wiping and sealing functions, it is necessary to
replace only the worn O-rings and not the entire connector.
Accordingly, it is one object of my invention to provide an
underwater disconnectable connector of the axial assembly type
which may be readily and inexpensively repaired should repair
become necessary.
It is a feature of our invention to provide an underwater
disconnectable connector having a plug of smaller cross-sectional
dimensions than its receptive socket to preclude wear of the plug
and socket.
A further object of our invention is to provide a connector that
may rapidly be connected or disconnected by means of a relatively
light assembling force without the aid of any special tools.
It may be appreciated further that as the connector is assembled,
arcing may occur between a socket contact and an approaching plug
contact. Accordingly, it is another object of our invention to
provide a connector in which any arcing that may occur will do so
in isolation from the surrounding environment and will be contained
between the O-rings. In this regard our connector is useful in an
explosive atmosphere where isolating of arcing is imperative.
Other objects and advantages of our invention will be apparent from
the following detailed description with reference to the
accompanying drawings wherein:
FIG. 1 is a longitudinal sectional view of our connector with the
plug fully inserted in the socket;
FIG. 2 is a longitudinal sectional view of a portion of the socket
illustrating the construction of the socket contacts and the
O-rings;
FIG. 3 is a view similar to that of FIG. 2 with the plug inserted
into the socket; and
FIG. 4 is a sectional view of the mated connector as viewed in the
plane of the line 4--4 of FIG. 1.
In the following description, for ease of explanation, the
direction in which the plug is inserted into the socket (left to
right in FIG. 1) will be referred to as "forward" and the opposite
direction (right to left as seen in FIG. 1) will be referred to as
"rearward."
As shown in FIG. 1 our connector includes a plug generally
indicated at 10 and a socket generally indicated at 12. The socket
12 has a cylindrical bore 14 which receives axially the forward end
of the plug 10 generally indicated at 16. The forward end or tip 16
of the plug 10 is cylindrical and of smaller cross-sectional
diameter than that of the socket bore 14 so that when the plug and
socket are mated a definite clearance 17 will exist between the
cylindrical surface 18 of the plug and the socket bore 14 (see FIG.
3). For example, in a connector having a plug tip 16 approximately
three-eighths of an inch in diameter the circumferential clearance
17 may be as little as 0.001 inch. A pair of contactor bands 20 and
22 are embedded within the end 16 of the plug. These bands are
circumferentially exposed about the surface 18 of the plug. The
exposed surface of each of the contactor bands 20, 22 is in flush
relation with the remainder of the tip 16 of the plug 10 and
defines a portion of the contiguous, flush, cylindrical surface 18
of the plug tip 16. The tip 16 itself is formed from a
nonconductive material so that it may effectively insulate the
embedded plug contacts 20 and 22 from each other. We have found
vacuum-type ceramic materials and moldable epoxy resins to be
suitable for this purpose. These materials have desirable
electrical insulating properties. The adhesive properties of epoxy
resins provide a firm bond to the metallic plug elements to make
the plug tip 16 rigid. If ceramic materials are used, they may be
cemented or brazed to the metal support.
The tip 16 of the plug 10 is joined securely to a rearwardly
extending connector tube 24 that guides the plug cable 26 and
contains the elements, described below, which effect electrical
connection between the cable 26 and socket contacts 20 and 22 of
the plug 10. As shown in FIG. 1, the plug cable 26 is of
conventional coaxial construction having an inner conductor 28 and
an outer conductor 30. The cable is connected electrically to the
forward tip 16 of the plug 10 by a coaxial plug-in connector
generally indicated at 32 which is a commercially available item
and includes an outer conductive sleeve 34, an intermediate
insulating sleeve 36 and an inner conductive sleeve 38. When
assembled, the inner conductor 28 of the cable 26 is received by
the inner sleeve 38 of the connector 32 and the outer coaxial
conductor 30 is wrapped about the rearward end of the outer sleeve
34. A length of tubing 40 is crimped about the assembled cable 26
and connector 32 to secure the two in a firm electrical connection.
An insulating bushing 42 may be placed about the connector 32
adjacent the crimped end of the outer coaxial conductor 28 to
preclude an uncrimped end of the conductor 26 from becoming short
circuited.
The connector 32 is received within a rearwardly extending portion
44 of a contact sleeve 46 which, as shown in FIG. 1, is formed
integrally with the plug contact 20 and engages electrically a
collar portion 48 of the outer sleeve 34 of the connector 32. This
establishes an electrical connection between the outer coaxial
conductor 30 and the plug contact 20.
The inner coaxial conductor 28 is electrically connected to the
plug contact 22 by a pin 50 which is brazed at its forward end to
the plug contact 22. The pin 50 extends rearwardly through the
contact sleeve 46 and is received within the inner sleeve 38 of the
plug-in connector 32 to establish electrical contact between the
inner coaxial conductor 28 and the plug contact 22.
The end piece 52 of the plug tip 16 is cemented or brazed to the
metal contact member 22 if it is made of ceramic material or is
molded to the member 22 if it is of epoxy material. Rings of
insulating material 54 and 56 (either ceramic or epoxy) are used to
separate the contacts 20 and 22 and also to electrically insulate
the contact 20 from the external environment. The rings 54 and 56
are attached to the contact sleeve 46 as illustrated. The ring 56
is reduced in diameter at its rear surface, as at 56a to receive
the forward end of the connector tube 24.
The socket assembly 12 includes a socket body 70 that is formed
from a readily machinable and electrically insulating material such
as polycarbonate plastic rod. A pair of expandable socket contact
rings 72 and 74 are contained within accommodating grooves 76 and
78 respectively which are formed at the cylindrical surface of the
inner bore 14 of the socket 12. The longitudinal spacing of the
grooves 76, 78 and their associated socket contacts 72, 74
corresponds to the longitudinal spacing of the plug contacts 20, 22
so that when the plug tip 16 is inserted fully into the socket 12
the mating contacts 20 and 72 as well as 22 and 74 will be in
proper electrical contact. As illustrated more clearly in FIG. 2,
the socket contact 72 has a plurality of inwardly projecting,
resilient fingers 73. The socket contact 74 is of identical
construction (see FIG. 4). The fingers of the contacts 72 and 74
respectively thus define an inner contact diameter smaller than
that of the diameter of the plug tip 16 so that when the plug 10 is
inserted into the socket 12 it engages and forces the fingers
radially apart. Thus when the plug 10 and socket 12 are mated the
fingers of the socket contacts 72, 74, by reason of their resilient
construction, press inwardly about the contactor bands 20, 22 of
the plug to firmly grip the plug and maintain an effective
electrical contact. It should also be noted that, when mated, the
reduced diameter of the plug at 16 provides the aforementioned
circumferential clearance.
As shown in FIG. 1, the socket 12 includes a hollow neck 75 which
receives the end of coaxial cable 76 having inner and outer
conductors 77, 78. A pair of slots 79, 81 are formed in the neck 75
to guide the conductors 77, 78 to terminal screws 83, 85. A pair of
conductive strips 87, 89 extend rearwardly from the screws 83, 85
along the exterior of the socket body 70, the strips 87, 89
terminating adjacent the socket contacts 72, 74 respectively. As
shown in FIG. 4, an opening 91 is formed in the socket body 70 to
expose the conductive strip 87 to its associated socket contact 74
and to enable the strip 87 and contact 74 to be electrically
connected as by a wire 93, for example. The opening 91 then is
sealed with an epoxy resin or other curable adhesive material 95.
The other strip is connected to its contact in substantially the
same manner.
It is imperative that when our connector is used in an underwater
environment each set of contact pairs 20, 72 and 22, 74 be sealed
from each other so that any water which may be trapped within the
clearance 17 of the assembled connector will not cause short
circuiting or a low-resistance path to occur between the sets of
contacts. For this purpose a number of resilient, compressible
O-rings 80, 82, 84 are contained within inner grooves 86, 88 and 90
respectively formed about the inner perimeter of the socket bore
14. The O-rings are desirably of larger cross section than those
that would be typically used in a conventional sealing application
so as to insure substantial contact along the surface of the plug
in the axial direction. That is, the thickness of each sealing
O-ring is considerably larger than the depth of the groove in which
is is seated and is considerably less than the width of that
groove. Thus as the plug 10 is inserted into the socket 12 the
O-rings are compressed radially and wipe the plug surface. When the
connector is assembled the O-rings press firmly against the
cylindrical surface of the plug 16 to effect a seal between each
adjacent set of contacts. Thus the contact 20, 72 is sealed between
the O-rings 80 and 82 and the contact 22, 74 is isolated between
the O-rings 82 and 84, the O-ring 82 serving as a common sealing
member between the contact pair. When our connector is assembled
under water the presence of residual water within the grooves 76
and 78 and in the clearance between the plug tip 16 and socket bore
14 will not cause short circuiting between the contact sets since
the O-ring seal is also electrically insulating.
An additional O-ring 92 may be provided at the entrance end of the
socket 12 for the purpose of wiping the plug tip 16 and socket
contacts 20, 22 free of dirt before the contacts are electrically
mated. Additional O-rings may also be provided at the sealing
locations if desired to provide greater reliability and a longer
leakage path to improve the electrical characteristics of the
connector. An opening 94 is provided at the forward end of the
socket to enable water to be ejected from the bore when the plug is
inserted and to enable water to freely flow back into the bore when
the plug is retracted. Our connector requires only a light force to
effect its connection or disconnection.
In some electrical circuits the presence of excess water or other
conductive medium about the electrically connected contacts may
deleteriously affect the integrity of the circuit. Furthermore,
when an electrical connector is completely surrounded by a
conductive medium the possibility of current leakage to the ambient
environment is present. When our connector is used under these
conditions, we prefer to coat the socket bore 14 with a
nonconductive, water-insoluble grease. A number of commercially
available silicone based greases may be used. The various grooves
formed within the socket should be completely filled. This may be
accomplished simply by placing some grease within the socket and
then reciprocating the plug tip 16 within the bore 14 until all the
grooves and clearances are filled. The resilient socket contacts
72, 74 remain effective to press and grip their associated plug
contacts 20, 22 and to make electrical contact even in the presence
of the grease.
Our connector also includes means for securely locking the plug 10
and socket 12 together after they have been electrically assembled.
To this end the socket body 70 is provided with a threaded exterior
portion 100 about the entrance to the socket which is cooperative
with a locknut 102 that is supported for rotation about the
connector sleeve 24. The connector sleeve 24 has a shoulder which,
at full engagement, abuts the entrance end of the socket body 70.
The shoulder 104 serves a dual purpose in that it determines the
extent to which the plug tip 16 may be inserted into the socket
bore 14 and serves as a retaining member to preclude the separation
of the lock nut 102 from the connector sleeve 24.
Protuberances 108 may be provided in the locknut 102 to facilitate
normal disengagement of the locknut 102 from the connector sleeve
24 after the connector has been assembled.
From the foregoing it will be apparent that we have provided a
versatile, reliable fluidproof connector that may be connected and
disconnected repeatedly within an electrically conductive
environment without displaying characteristics adverse to the
functioning of the electrical circuit in which the connector is
used.
The foregoing description is intended only to be illustrative of
our invention which may be modified by those skilled in the art
without departing from its spirit. For example, although the
connector has been described as having two pairs of connectable
contacts, it is, of course, possible to construct a connector
having any number of contacts, with each of the contacts being
isolated by one or more O-rings or similar yieldable, resilient
sealing members.
It should be noted that, although the illustrative embodiment of
the invention is directed to a plug and socket of circular
cross-sectional configuration, an oval or other noncircular
cylindrical cross section may be used. When such a noncircular
connector is used care should be taken to insure that the
configuration is such that O-rings will completely isolate each
pair of connected contacts when the connector is assembled. The
cross sectional dimensions of the plug must, of course, be smaller
than the corresponding dimension of the socket to provide the
required clearance. Further, although we have shown our connector
in connection with a two conductor coaxial cable, it is apparent
that it might be used with cables of the noncoaxial type and with
multiple conductor cables.
* * * * *