Information
-
Patent Grant
-
6508293
-
Patent Number
6,508,293
-
Date Filed
Thursday, September 6, 200122 years ago
-
Date Issued
Tuesday, January 21, 200321 years ago
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Inventors
-
-
Examiners
Agents
- Ohlandt, Greeley, Ruggiero & Perle, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 160 170 R
- 160 1681 R
- 160 171 R
- 160 172 R
- 160 8402
- 160 8404
- 160 8406
- 160 191
- 160 192
- 160 193
- 267 155
- 267 156
- 185 37
- 185 39
- 185 45
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International Classifications
-
Abstract
A spring motor assembly for a Venetian blind includes a bracket formed with confronting insert grooves, a pair of insert plates inserted into the insert grooves, two parallel axles extending transversely between the insert plates, a storage drum mounted rotatably on one of the axles, co-axial and co-rotatable output drum and cord spool mounted rotatably on the other of the axles, and a coil spring extending between the storage drum and the output drum. The bracket is mounted on a top rail of the Venetian blind. The cord spool engages upper ends of two lifting cords of the Venetian blind. The coil spring is wound on at least one of the storage drum and the output drum, and is transferred from one of the drums to the other of the drums when a bottom bar of the Venetian blind is moved upwardly or downwardly relative to the top rail.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spring motor assembly for use in a Venetian blind that has no outside hanging lifting cords, more particularly to a spring motor assembly that provides a driving force for driving raising or lowering movement of slats of the Venetian blind.
2. Description of the Related Art
U.S. Pat. No. 5,482,100 discloses a Venetian blind without outside hanging lifting cords. The Venetian blind has a spring motor mounted on a top rail thereof. The spring motor is coupled to a pair of lifting cords of the Venetian blind, and provides driving forces for raising or lowering a plurality of horizontal slats that are suspended from the top rail. The spring motor includes a bracket having a back wall and a pair of side walls that extend transversely from the back wall and that cooperate with the back wall to form the bracket with a generally U-shaped configuration. The bracket further has a pair of attached plates on the side walls for fastening to the top rail. Two axles are secured onto the back wall for mounting a spring storage drum, a spring output drum and a cord spool that is co-axial and co-rotatable with the output drum. The lifting cords extend through the slats, and have lower ends connected to a bottom bar and upper ends coupled to the cord spool.
A coil spring has a first end coupled to the storage drum and an opposite second end coupled to the output drum, and is transferred from one of the drums to the other of the drums when the bottom bar moves with respect to the top rail.
When the slats are raised, the weights thereof are applied to the lifting cords, and in turn, to the cord spool and the axle that supports the cord spool. Since the axles are each connected to the bracket at only one end thereof, they are susceptible to vibration due to the weights of the slats applied thereon during operation for raising or lowering the slats, thereby adversely affecting smooth raising and lowering movement of the slats. Moreover, as the axles are fastened to the back wall by screws or rivet, loosening of the axles from the back wall is likely to occur.
SUMMARY OF THE INVENTION
Therefore, the main object of the present invention is to provide a spring motor assembly of the aforementioned type and with a firmer and more stable construction to ensure smooth raising and lowering movement of Venetian blind slats.
Accordingly, the spring motor assembly of the present invention is adapted for use in a Venetian blind that includes a top rail, a plurality of horizontal slats suspended from the top rail, a horizontal bottom bar disposed below the slats, and a pair of lifting cords, each of which extends through the slats and has an upper end extending into the top rail and a lower end connected to the bottom bar. The spring motor assembly of the present invention includes a bracket, a pair of insert plates, parallel first and second axles, a storage drum, an output drum, a cord spool, and a coil spring. The bracket is adapted to be installed on the top rail, and includes parallel front and back walls, and a pair of lateral side walls interconnecting the front and back walls and cooperating with the front and back walls to confine a receiving chamber with a top opening. Each of the front and back walls has an inner wall surface that confronts the other of the front and back walls. The front and back walls further have upper edges that define the top opening. The inner wall surface of each of the front and back walls is formed with an insert groove that extends downwardly from the upper edge and that has an open upper end formed through the upper edge. Each of the lateral side walls is formed with a cord opening communicated with the receiving chamber and adapted to permit extension of a respective one of the lifting cords therethrough. Each of the insert plates is inserted into the insert groove in a respective one of the front and back walls via the open upper end, and is retained therein. The first and second axles are mounted on the insert plates and extend transversely between the insert plates. The storage drum is mounted rotatably on the first axle. The output drum is mounted rotatably on the second axle. The cord spool is mounted rotatably on the second axle so as to be co-rotatable with the output drum. The cord spool is adapted to engage the upper ends of the lifting cords and to permit winding of the lifting cords therearound. The coil spring has a first end engaging the storage drum, and a second end opposite to the first end and engaging the output drum. The coil spring is wound around at least one of the storage drum and the output drum, and is transferred from one of the storage drum and the output drum to the other of the storage drum and the output drum when the bottom bar of the Venetian blind is moved with respect to the top rail in a vertical direction.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
FIG. 1
is an exploded perspective view of a preferred embodiment of a spring motor assembly of the present invention;
FIG. 2
is an assembled perspective view of the preferred embodiment;
FIG. 3
is a cross-sectional side view of the preferred embodiment;
FIG. 4
is a cross-sectional top view of the preferred embodiment; and
FIG. 5
is a schematic view of a Venetian blind that incorporates the spring motor assembly of the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIGS. 1 and 2
, the preferred embodiment of the springmotor assembly
100
of the present invention is shown to include a bracket
10
, a pair of insert plates
20
, parallel first and second axles
30
,
40
, a storage drum
50
, an output drum
60
, a cord spool
70
, and a coil spring
80
.
The bracket
10
is formed as a hollow rectangular casing, and includes upright front and back walls
13
disposed parallel to each other, and a pair of side walls
14
interconnecting lateral ends of the front and back walls
13
and cooperating with the front and back walls
13
to confine a receiving chamber
15
that has a top opening
151
. Each of the side walls
14
is formed with a rectangular cord opening
141
communicated with the receiving chamber
15
. Each of the front and back walls
13
has an inner wall surface
131
which confronts the other of the front and back walls
13
and which is formed with an insert groove
134
that extends downwardly from an upper edge
11
of the respective one of the front and back walls
13
and that has an open upper end
135
formed through the upper edge
11
and communicated with the top opening
151
of the receiving chamber
15
. The insert groove
134
is in the form of a dovetail groove with a narrower end proximate to the other of the front and back walls
13
and communicated with the receiving chamber
15
, and a wider end distal to the other of the front and back walls
13
. The insert groove
134
in each of the front and back walls
13
is defined by a pair of spaced apart inclined lateral faces
133
, a connecting face
136
, and a horizontally extending bottom face
132
. The lateral faces
133
extend downwardly from the upper edge
11
of the respective one of the front and back walls
13
, and have upper ends defining the open upper end
135
of the insert groove
13
, inner ends defining the narrower end of the dovetail groove
134
, and outer ends defining the wider ends of the dovetail groove
134
. The connecting face
136
extends between the outer ends of the lateral faces
133
. The bottom face
132
faces upwardly and extends between lower ends of the lateral faces
133
.
Each of the insert plates
20
is inserted into the insert groove
134
in a respective one of the front and back walls
13
via the open upper end
135
of the insert groove
134
, and has a size and shape conforming with those of the insert groove
134
. Each of the insert plates
20
has a bottom edge
21
abutting against the bottom face
132
of the insert groove
134
, and lateral edges
22
engaging the lateral faces
133
of the insert groove
134
. The insert plates
20
are formed with aligned first axle holes
23
, and aligned second axle holes
24
.
The first axle
30
is mounted on the insert plates
20
by extending a pair of pin projections
31
formed at two opposite ends thereof into the first axle holes
23
in the insert plates
20
. The second axle
40
is mounted on the insert plates
20
by similarly extending a pair of pin projections
41
formed at two opposite ends thereof into the second axle holes
24
in the insert plates
20
.
The spring storage drum
50
has a cylindrical body
51
sleeved rotatably on the first axle
30
, and a pair of annular walls
52
cooperating with the cylindrical body
51
to define a spring storage space for storing the coil spring
80
. The cylindrical body
51
has an outer surface formed with a first engaging hole
53
for engaging a first end
81
of the coil spring
80
.
The output drum
60
is connected co-axially and co-rotatably to the cord spool
70
. In the present embodiment, the output drum
60
is formed integrally with the cord spool
70
. The assembly of the output drum
60
and the cord spool
70
is sleeved rotatably on the second axle
40
such that the output drum
60
is juxtaposed to the storage drum
50
. The output drum
60
similarly has a cylindrical body
61
extending transversely between a parallel pair of annular walls
62
so as to cooperatively confine a spring receiving space. The cylindrical body
61
is formed with a second engaging hole
63
in its outer surface for engaging a second end
82
of the coil spring
80
opposite to the first end
81
. The cord spool
70
is adapted to engage upper ends of a pair of lifting cords of a Venetian blind, and confines an annular cord winding space adapted to permit winding of the lifting cords therearound.
Referring to
FIGS. 3 and 4
, preferably, the upper ends of the lifting cords
91
are initially attached to the cord spool
70
in a conventional manner before assembly. During assembly of the spring motor assembly
100
of the present invention, the coil spring
80
is installed on the storage drum
50
by extending the first end
81
into the first engaging hole
53
to engage the storage drum
50
and by winding the coil spring
80
around the storage drum
50
, which is then sleeved on the first axle
30
. The assembly of the output drum
60
and the cord spool
70
is sleeved on the second axle
40
. Then, the first and second axles
30
,
40
are installed on the insert plates
20
by extending the pin projections
31
,
41
into the first and second axle holes
23
,
24
, respectively. Thereafter, the insert plates
20
are inserted into the dovetail grooves, i.e., the insert grooves
134
, via the upper ends
135
of the insert grooves
134
so as to dispose the storage drum
50
, the output drum
60
and the cord spool
70
in the receiving chamber
15
of the bracket
10
. Finally, the second end
82
of the coil spring
80
is drawn upwardly for engaging the second engaging hole
63
in the output drum
60
, and the lifting cords
91
are extended out of the bracket
10
via the cord openings
141
in the side walls
14
. After assembly, the insert plates
20
engage fittingly the insert grooves
134
so as to position the axles
30
,
40
, the storage drum
50
, the output drum
60
and the cord spool
70
on the bracket
10
.
Referring to
FIG. 5
, in practice, the spring motor assembly
100
of the present embodiment is mounted on a top rail
200
of a Venetian blind. The lifting cords
91
extend out of the top rail
200
via through holes
201
formed in a bottom wall of the top rail
200
. The lifting cords
91
extend through a plurality of horizontal slats
300
that are suspended from the top rail
200
. Lower ends of the lifting cords
91
are connected to a horizontal bottom bar
400
that is disposed below the slats
300
. In use, when the bottom bar
400
is pulled downwardly for lowering the slats
300
, the cord spool
70
and the output drum
60
are driven by the coil spring
80
to rotate in a direction for winding the coil spring
80
on the output drum
60
and for unwinding the lifting cord
91
from the cord spool
70
. When the downward pulling force is removed while the bottom bar
400
reaches a desired altitude, the spring force of the coil spring
80
is just sufficient to maintain the bottom bar
400
at the desired position and to prevent dropping and self-raising of the bottom bar
400
. When the pulling force is applied continuously to enable the slats
300
to reach the fully lowered position shown in
FIG. 5
, most of the coil spring
80
is wound around the output drum
60
with its first end
82
attached to the storage drum
50
. On the other hand, when it is desired to raise the slats
20
, the bottom bar
400
is urged upwardly, such as by applying an upward pushing force thereat. At this time, the cord spool
70
and the output drum
60
are driven by the coil spring
80
to rotate in another direction for winding the coil spring
80
on the storage drum
50
and for winding the lifting cords
91
on the cord spool
70
. When the upward pushing force is removed while the slats
300
and the bottom bar
400
reach a desired position, the spring force of the coil spring
80
is just sufficient to maintain the bottom bar
400
at the desired position and to prevent self-raising and dropping of the bottom bar
400
. When the bottom bar
400
is continuously urged upwardly to enable the slats
300
to reach the entirely raised position in which all of the slats
300
are accumulated on the bottom bar
400
, the coil spring
80
is substantially transferred from the output drum
60
to the storage drum
50
with its second end
82
attached to the output drum
60
. The orientation of the coil spring
80
, as it is transferred from the output drum
60
to the storage drum
50
, is reversed.
Note that each of the first and second axles
30
,
40
engages the insert plates
20
at two opposite ends thereof. The insert plates
20
are inserted into the dovetail grooves
134
of the bracket
10
. The entire construction of the spring motor assembly
100
is relatively firm and stable so as to support the weights of the slats
300
and the bottom bar
400
in order to ensure smooth raising and lowering movement of the slats
300
of the Venetian blind. In addition, without the need for a fastener, such as screws of rivets, the axles
30
,
40
can be easily assembled to the insert plates
20
, which, in turn, can be easily assembled to the bracket
10
. The engagement between the axles
30
,
40
and the insert plates
20
and between the insert plates
20
and the bracket
10
is relatively secure. Moreover, the bracket
10
may be designed to have a size and shape conforming with an interior cross-section of the top rail
200
such that the bracket
10
can be retained fittingly and securely in the top rail
200
without the need for using fastening screws.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Claims
- 1. A spring motor assembly for a Venetian blind having a top rail, a plurality of horizontal slats suspended from the top rail, a horizontal bottom bar disposed below the slats, and a pair of lifting cords, each of which extends through the slats and has an upper end extending into the top rail and a lower end connected to the bottom bar, said spring motor assembly comprising:a bracket adapted to be installed on the top rail, said bracket including parallel front and back walls, and a pair of lateral side walls interconnecting said front and back walls and cooperating with said front and back walls to confine a receiving chamber with a top opening, each of said front and back walls having an inner wall surface that confronts the other of said front and back walls, said front and back walls further having upper edges that define said top opening, said inner wall surface of each of said front and back walls being formed with an insert groove that extends downwardly from said upper edge and that has an open upper end formed through said upper edge, each of said lateral side walls being formed with a cord opening communicated with said receiving chamber and adapted to permit extension of a respective one of the lifting cords therethrough; a pair of insert plates, each of which is inserted into said insert groove in a respective one of said front and back walls via said open upper end and is retained thereon; parallel first and second axles mounted on said insert plates and extending transversely between said insert plates; a storage drum mounted rotatably on said first axle; an output drum mounted rotatably on said second axle; a cord spool mounted rotatably on said second axle and co-rotatable with said output drum, said cord spool being adapted to engage the upper ends of the lifting cords and to permit winding of the lifting cords therearound; and a coil spring having a first end engaging said storage drum and a second end opposite to said first end and engaging said output drum, said coil spring being wound around at least one of said storage drum and said output drum and being transferred from one of said storage drum and said output drum to the other of said storage drum and said output drum when the bottom bar of the Venetian blind is moved with respect to the top rail in a vertical direction.
- 2. The spring motor assembly as claimed in claim 1, wherein said insert plates are formed with aligned first axle holes and aligned second axle holes, said first axle having two opposite ends, each of which is formed with a pin projection that extends into and that engages said first axle hole in a respective one of said insert plates, said second axle having two opposite ends, each of which is formed with a pin projection that extends into and that engages said second axle hole in a respective one of said insert plates.
- 3. The spring motor assembly as claimed in claim 1, wherein said insert groove in each of said front and back walls of said bracket is a dovetail groove with an open narrower end proximate to the other of said front and back walls, and a wider end distal to the other of said front and back walls.
- 4. The spring motor assembly as claimed in claim 3, wherein said insert groove is defined by:a pair of spaced-apart lateral faces which are inclined relative to said front and back walls, which have inner ends defining said narrower end of said dovetail groove and outer ends defining said wider end of said dovetail groove, and which have upper ends defining said open upper end of said insert groove, and lower ends opposite to said upper ends; a connecting face extending between said outer ends of said lateral faces; and a horizontal bottom face that faces upwardly and that extends between said lower ends of said lateral faces.
US Referenced Citations (12)