U.S. patent number 3,830,554 [Application Number 05/365,805] was granted by the patent office on 1974-08-20 for locking device for sewing machine cabinet support platforms.
This patent grant is currently assigned to The Singer Company. Invention is credited to Gilles Maillart, Gregoire Moussaian.
United States Patent |
3,830,554 |
Moussaian , et al. |
August 20, 1974 |
LOCKING DEVICE FOR SEWING MACHINE CABINET SUPPORT PLATFORMS
Abstract
A sewing machine cabinet having a sewing machine support
platform pivotable about a fixed axis from a stored position within
the cabinet to a substantially horizontal operative position where
it is locked in place by means of a pair of bolts mounted on
opposite sides of the platform, and received within sockets formed
on corresponding keepers pivotably mounted on brackets secured on
the cabinet side walls. Each keeper includes three cam surfaces,
two of which are effective to rotate the keeper in a first
direction when acted upon by respective bolts. A spring secured to
each keeper to oppose the rotation of keeper in the first direction
until the keeper rotates to a position where the spring swings
over-center and thereafter aids turning the keeper in this
direction. The third cam surface is effective to turn the keeper in
the opposite direction to that of the first two cam surfaces. As
the platform is pivoted into the operative position the bolts
engage the first cam surface and rotate the keeper against the bias
of the springs. When the bolts are above the sockets the springs
return the keepers to the normal positions and the platform may be
lowered to position the bolts into the socket. To store, the
platform is pivoted upwardly until the bolts engage the second
surface rotating the keepers until the springs have moved
over-center. The platform is then moved downwardly free of the
sockets and engage the third surface to rotate the keepers into
their original position.
Inventors: |
Moussaian; Gregoire (Freneuse,
FR), Maillart; Gilles (Cerise, FR) |
Assignee: |
The Singer Company (New York,
NY)
|
Family
ID: |
23440442 |
Appl.
No.: |
05/365,805 |
Filed: |
May 31, 1973 |
Current U.S.
Class: |
312/30;
112/217.1; 292/DIG.49; 292/DIG.4 |
Current CPC
Class: |
A47B
29/00 (20130101); D05B 75/06 (20130101); Y10S
292/04 (20130101); Y10S 292/49 (20130101) |
Current International
Class: |
A47B
29/00 (20060101); D05B 75/06 (20060101); D05B
75/00 (20060101); A47b 081/00 () |
Field of
Search: |
;312/21.27,30
;112/217.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mitchell; James C.
Attorney, Agent or Firm: Breen; Marshall J. Williams, Jr.;
Chester A. Ruderman; Alan
Claims
Having thus set forth the nature of the invention, what is claimed
herein is:
1. In a sewing machine cabinet having a sewing machine support
platform adapted to pivot about a first axis from a substantially
vertically inclined stored position within the cabinet to a
substantially horizontally inclined operative position, mechanism
for supporting and locking the platform in the operative position
and for releasing the same for pivoting into the stored position,
said mechanism comprising: a bolt mounted on said platform spaced
from said axis for movement in a path about said first axis; a
keeper comprising first, second and third cam surfaces and a socket
normally lying in said path and adapted to receive said bolt;
journal means for mounting said keeper on said cabinet for
pivotable movement about a second axis spaced from said path; said
first and second cam surfaces having portions normally lying in
said path, whereby movement of said platform to engage said bolt
selectively with said first and second cam surfaces turns said
keeper in one direction; each of said first and second surfaces
being inclined so that continued upward movement of said platform
from the stored position continues to move said keeper in said one
direction; biasing means acting on the keeper for exerting a
turning force about said second axis in opposition to said one
direction and upon said keeper reaching a predetermined position in
said one direction for exerting a turning force about said second
axis in said one direction; said first cam surface terminating
above said socket at a point which leaves said path prior to said
keeper reaching said predetermined position, whereby said socket is
returned to said path and said bolt may be lowered therein; said
second cam surface being disposed above said socket and
substantially terminating at a point crossing said path when the
keeper is in said predetermined position; stop means for preventing
further movement of said keeper in said one direction substantially
beyond said predetermined position; said third cam surface being
spaced from said first cam surface and having a portion lying in
said path when said keeper is in the predetermined position,
whereby said keeper may be turned in a direction opposite to said
one direction when said platform is lowered to said stored
position, said biasing means thereafter returning said keeper in
said one direction.
2. In a sewing machine cabinet as recited in claim 1 wherein said
biasing means comprises a spring, means securing one end of said
spring to said cabinet, means for connecting the other end of said
spring to the keeper at a location normally positioned on one side
of said second axis and which is on the other side of said second
axis when the keeper is turned to said predetermined position.
3. In a sewing machine cabinet as recited in claim 2 wherein said
journal means comprises a bracket secured to said cabinet, a pin
journaled on said bracket, and means for mounting said keeper on
said pin.
4. In a sewing machine cabinet as recited in claim 3 wherein said
stop means comprises a ledge formed on said bracket.
5. In a sewing machine cabinet as recited in claim 4 wherein said
means for securing said one end of the spring to the cabinet
includes said ledge.
6. In a sewing machine cabinet as recited in claim 4 wherein said
bracket includes a second ledge, said second ledge providing a stop
for preventing movement of said keeper in a direction opposite to
said one direction when said platform is in the operative
position.
7. In a sewing machine cabinet as recited in claim 1 wherein a bolt
is mounted on opposite sides of said platform and a corresponding
keeper is mounted on opposite sides of said cabinet.
8. A keeper mechanism for receiving a bolt secured to a pivotable
sewing machine cabinet support platform for locking and supporting
said platform in a substantially horizontally inclined operative
position, and for releasing the same for storage in a substantially
vertically inclined storage position within the cabinet, said
keeper mechanism comprising: a pivotable keeper adapted to be
mounted on the cabinet for pivotable movement about an axis spaced
from a path defined by movement of said bolt; said keeper including
a socket, first, and second cam surfaces having portions normally
lying in said path, whereby movement of said platform to engage
said bolt selectively with said first and second cam surfaces turns
said keeper in one direction; each of said first and second
surfaces being inclined so that continued upward movement of said
platform from the stored position continues to move said keeper in
said one direction; biasing means acting on the keeper for exerting
a turning force about said axis in opposition to said one direction
and upon said keeper reaching a predetermined position in said one
direction for exerting a turning force about said axis in said one
direction; said first cam surface terminating above said socket at
a point which leaves said path prior to said keeper reaching said
predetermined position, whereby said socket is returned to said
path and said bolt may be lowered therein; said second cam surface
being disposed above said socket and substantially terminating at a
point crossing said path when the keeper is in said predetermined
position; stop means for preventing further movement of said keeper
in said one direction substantially beyond said predetermined
position; said keeper further including a third cam surface spaced
from said first cam surface and having a portion lying in said path
when said keeper is in the predetermined position, whereby said
keeper may be turned in a direction opposite to said one direction
when said platform is lowered to said stored position, said biasing
means thereafter returning said keeper in said one direction.
9. A keeper mechanism as recited in claim 8 wherein said biasing
means comprises a spring, means adapted for securing one end of
said spring to said cabinet, means for connecting the other end of
said spring to the keeper at a location normally positioned on one
side of said axis and which is on the other side of said axis when
the keeper is turned to said predetermined position.
Description
BACKGROUND OF THE INVENTION
This invention relates to a locking device, and more particularly
to a mechanism for supporting and locking a sewing machine cabinet
support platform in the operative position, and for releasing the
same for movement of the platform to the stored position.
In sewing machine cabinets of the drop-head type, a platform
carrying the sewing machine is lifted into the sewing machine
operating position and lowered to its stored position within the
cabinet. Some means must, of course, be provided for securing the
platform in the operative position and for releasing the same for
movement into the stored position. In the prior art various
arrangements have been provided for accomplishing this result.
These vary from merely resting the sewing machine base on the
cabinet top by using a hinged front rail to complicated devices
used in conjunction with the platforms that translate vertically.
These arrangements are either unsatisfactory for cabinets designed
for sewing machines operable in both flat bed and cylinder bed
mode, or are exceedingly expensive. Moreover, these arrangements
require that both hands be utilized to release the platform, some
even requiring the placing of a hand in a blind location and may
thereby create a dangerous condition to an operator.
SUMMARY OF THE INVENTION
These objections and deficiencies of the prior art are overcome by
the present invention which provides an efficient, inexpensive and
safe device for cabinets having pivotably mounted sewing machine
support platforms for locking and securing the platform in the
operative position and for releasing the platform for pivoting into
the stored position. The device comprises a pivotable keeper having
a socket, three cam surfaces and a spring secured to the keeper at
a location which effects an over-center shifting of the spring when
the keeper is pivoted beyond a predetermined position. The platform
has a bolt adapted to be received within the socket of the keeper
after turning the keeper by its action with the first cam surface.
To release the platform it is first lifted so that the bolt turns
the keeper by means of the second cam surface until the spring
moves over-center and holds the keeper against a stop. At this
point, the platform may be pivoted downwardly, the bolt engaging
the third cam surface to return the keeper and spring to their
initial positions.
It is therefore a primary object of this invention to provide a
simple, safe and inexpensive mechanism for locking and supporting a
pivotable sewing machine platform in the operative position and for
releasing the platform to allow it to pivot into a stored position
within a cabinet.
It is another object of this invention to provide a pivotable
keeper on a sewing machine cabinet to cooperate with a bolt mounted
on a sewing machine support platform for locking and supporting the
platform in an operative position and for releasing the platform
for storage within the cabinet.
It is a further object of this invention to provide a pivotable
keeper and a shiftable biasing member to cooperate with a bolt
mounted on a sewing machine support platform for locking and
supporting the platform in an operative position and for releasing
the platform for storage within the cabinet.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the invention will become
apparent from the following description of the invention taken in
connection with the following drawings, in which:
FIG. 1 is a perspective view, partly in section, of a portion of a
sewing machine cabinet having a pivotably mounted sewing machine
support platform in the stored position and illustrating a
preferred embodiment of the locking device of the present
invention;
FIG. 2 is an enlarged perspective view, partly in section, of a
portion of the cabinet of FIG. 1 with the sewing machine support
platform in the operative position, but with the bolt disassembled
from the keeper for clarity;
FIG. 3 illustrates diagrammatically an initial position of the
locking device as the platform is raised;
FIG. 4 is a view similar to that of FIG. 3 showing the positions
just prior to locking of the platform in the operative
position;
FIG. 5 is a similar view, but illustrating the relative positions
of the elements of the locking device of the present invention as
the platform is initially lifted from the operating position to
disengage the bolt from the keeper;
FIG. 6 is a position similar to FIG. 5 illustrating the location of
the elements as the direction of movement of the platform changes
from upward to downward and just subsequent to the spring shifting
over-center of the keeper pivot axis; and
FIG. 7 is a view similar to that of FIG. 6 but illustrating the
location of the elements as the platform is lowered to the stored
position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompanying drawings in which like reference
numerals denote similar parts throughout the various views, FIG. 1
illustrates a sewing machine cabinet generally designated as 10 and
including a pair of side walls 12 and 14 supporting a substantially
U-shaped top 16. Hingedly secured to the top may be a leaf 18 for
aesthetically covering the top and for providing an extended work
surface area during sewing. A front door 20 may be hingedly secured
to one of the walls 14 to enclose the front portion of the cabinet
during nonuse. A front rail 22 which may be pivoted as disclosed in
copending U.S. Pat. application Ser. No. 351,667, filed Apr. 16,
1973, now U.S. Pat. No. 3,797,425, is located between the sides 12
and 14 at the front edge of the top. Pivotably mounted within the
cabinet by means of hinges 24, (only one of which is illustrated),
is a sewing machine support platform 26. The hinges 24 are secured
to the platform 26 and to the bottom surface of the top 16 and
defines an axis about which the support platform may be pivoted
into and from the stored vertical position as illustrated in FIG.
1, to a substantially horizontal operative position as illustrated
in FIG. 2. The bed 28 of a sewing machine, generally illustrated as
numeral 30, is conventionally secured to the platform 26 so as to
be positioned at the proper elevation relative to the cabinet top
16 when the platform is in the operative position. To lock and
secure the platform 28 in the horizontal operative position there
is provided by this invention, a mechanism comprising a stud or
bolt 32 preferably located at each side of the platform adjacent
the front edge thereof, and a pivotably mounted cam and socket
means 34 preferably mounted on the interior of the walls 12 and 14
as hereinafter described.
The member 32, as will be clearly understood as this description
proceeds, is a securing element movable into cooperative engagement
with a keeper member and is herein designated a "bolt" to be
consistent with the terminology used in the locking art. It should,
however, be understood that the bolt 32 is secured to the platform
28 and therefore moves in a circular path about the axis provided
by the hinges 24. The cam and socket means 34 preferably includes a
substantially U-shaped (in plan) bracket 36 secured at the cross
leg 38 by conventional screws 40 to the inside surfaces of the
walls 12 and 14. The bracket is conveniently designed so that its
outstanding walls 42 and 44 may serve purposes which will
hereinafter become clear. The cross leg 38 preferably includes an
apertured boss 45 within which is journaled a stud shaft 46.
Secured to the stud shaft 46 is a unique movable keeper 48, the
stud shaft being understood to define a pivot axis for the keeper.
The term "keeper" being a lock art term designating the part which
receives the bolt and this term will be utilized herein.
As illustrated, the keeper 48 is somewhat U-shaped in elevation,
being secured on its cross leg 50 to the stud shaft 46 and
preferably having a pair of normally substantially downwardly
extending legs 52 and 54. Connected at one end in a hole 57 in the
cross leg, preferably spaced from and above the stud shaft 46, is
an extension spring 56 having its other end secured in a hole 58
formed in the bracket leg 42, The spring is spaced from the stud
shaft 46 to normally bias the keeper counterclockwise, as
illustrated in the drawings, about the stud shaft 46 and to bias it
clockwise when the keeper has turned clockwise to a position in
which the spring swings over-center. The spring is of a size such
that the keeper is properly positioned in the initial position of
FIG. 3 as hereinafter described. However, to allow for
manufacturing tolerances the bracket leg 44 may act as a stop to
prevent the keeper from turning counterclockwise from its normally
disposed position.
The leg 52 is substantially wider than the leg 54 and is formed
with an inclined surface 60 which defines a first cam surface. The
cam surface 60 steeply extends from a point 62 at its lower end to
a point 64 at its upper end from whence the surface extends at an
obtuse angle until its termination at point 66. Spaced inwardly
from the cam surface 60 toward the body of leg 52 and recessed
below the point 66 is a socket 68 of a size sufficient to receive
the bolt 32 with a minimum of play therebetween. With particular
reference to FIG. 3, it is seen that the bolt 32 moves along a path
designated as BP, and that in the normal position of the keeper the
bottom edge 62 of the cam surface 60 is at or below said path.
Thus, as the platform 28 is lifted manually the bolt 32 will engage
the cam surface 60 and turn the keeper clockwise about the shaft
46. The steepness of the cam surface 60 insures a gradual turning
of the keeper until it has turned so that the point 64 passes the
path BP. From this point the keeper no longer turns but as the bolt
continues to move upwardly it is elevated above the socket 68.
Thus, when the bolt passes the termination point 66, the cam
surface leaves the path of the bolt and the spring 56 effectively
returns the keeper counterclockwise about the shaft 46 to its
initial position. The platform may then be lowered to the
horizontal position whereby the bolt is received within the socket
68 which thereby locks and supports the bolt and the platform
therewith. The steps during the locking operation are illustrated
sequentially in FIGS. 3 and 4, and the platform locking position is
illustrated in FIG. 2.
The inner facing edge 70 of the leg 52 is inclined upwardly from
the socket along a straight line substantially approximating the
path of the bolt and is spaced from the center of the socket, so
that when the platform is lifted to remove the bolt from the
socket, the keeper preferably does not turn. However, since it is
more economical to manufacture the edge 70 as a straight surface
rather than the true radius of path BP, the keeper practically
turns slightly as illustrated in FIG. 5. The edge 70 extends to a
first inner edge 72 of the leg 50 at a point 74 from whence the
edge 72 extends to a point 76 substantially vertically below the
stud shaft 46 when the keeper is in the normal or initial position.
The edge 72 defines a second cam surface effective during the
returning of the platform 28 to the stored position. Since the
relation of the cam surface 72 to the path BP is initially almost
perpendicular, the bolt 32 causes the keeper to turn rapidly
clockwise about the pivot 46. Substantially, when the bolt is
located at the point 76, the keeper has turned to a position where
the spring 56 crosses from above the pivot shaft 46 to below the
shaft. This over-center movement of the spring quickly snaps the
keeper further clockwise about the axis 46. To prevent the keeper
from spinning and to stop its motion, the keeper leg 52 has a
surface 78 adapted to abut against the bracket leg 42. Thus, when
the keeper is in the stopped position the platform direction may
change from the upward direction to a lowering. The relative
positions of the bolt and keeper in this stopped position of the
keeper is illustrated in FIG. 6.
Extending from the point 76 of the cam surface 72 is a second inner
edge 80 of the leg 50. This edge is inclined so that a downward
movement of the platform when the bolt is located at the stop
position of FIG. 6 is ineffective to turn the keeper. The leg 54 of
the keeper includes on its inner surface a substantially straight
abutment or third cam surface 82 having at least a portion lying in
the path BP when the keeper is located as illustrated in FIG. 6.
Thus, with the bolt in this position, the platform is lowered and
the bolt strikes the surface 82 to rotate the keeper
counterclockwise. This lowering is done with a single continuous
motion and as the keeper turns to a position where the spring 56 is
again above the pivot axis 46, the spring quickly snaps the keeper
to the initial position (such as that of FIG. 3) as the bolt freely
passes between the legs 52 and 54. The platform is thereby released
to return to the stored position of FIG. 1.
Although the description has centered on the keeper and bolt on one
side of the cabinet only, it is to be understood that a similar
arrangement may be located on the other side of the cabinet so as
to insure that the platform is stable when in the operating
position of the sewing machine. Moreover, it should be understood
that the spring 56, although in the preferred embodiment is
normally located above the pivot axis 46, may be initially located
somewhat differently than disclosed. However, the important thing
about the spring 56 is that it swings over-center of the pivot axis
when the keeper has reached a certain predeterined position to
quickly turn the keeper in a direction opposite to that initially
biased by the spring and to aid in stopping the keeper from moving
and positioning it for the lowering of the platform.
It should thus be clear that a simple and effective locking,
securing and releasing device is provided by the present invention
which meets all the objectives of this application and overcomes
the deficiencies of the prior art. Numerous alterations of the
structure herein disclosed will suggest themselves to those skilled
in the art. However, it is to be understood that the present
disclosure relates to a preferred embodiment of the invention which
is for purposes of illustration only and not to be construed as a
limitation of the invention. All such modifications which do not
depart from the spirit of the invention are intended to be included
within the scope of the appended claims.
* * * * *