Title: Planetary gear actuator apparatus and method
Abstract: A traction cable actuator has a sun gear, with a lever, at least two planetary gears engaged with the sun gear, and a housing with a toothed race engaging the planetary gears. The housing further has a lock spring seat, and a traction cable sleeve seat. A drive shaft operatively engages with the sun gear to turn the sun gear. The shaft has at least one release tab. A pulley is disposed within the housing. The pulley has planetary gear axles disposed to receive driving force from the planetary gears. The pulley also has a traction cable wire seat. A lock spring disposed to engage said lock spring seat in the housing engages the lever on the sun gear when the sun gear is turned. The lock spring holds said pulley in a position selected by turning the drive shaft. A bearing and groove stop assembly may be included.
Patent Number: 6,997,847 Issued on 02/14/2006 to Liu
| Inventors:
|
Liu; Jintao (Windsor, CA)
|
| Assignee:
|
L&P Property Management Company (South Gate, CA)
|
| Appl. No.:
|
765353 |
| Filed:
|
January 27, 2004 |
| Current U.S. Class: |
475/317; 475/349; 475/900 |
| Current Intern'l Class: |
F16H 3/44 (20060101); F16H 57/08 (20060101); F16H 57/10 (20060101) |
| Field of Search: |
475/269- 70,282,301,317,331,349,900
|
References Cited [Referenced By]
U.S. Patent Documents
| 1684185 | Sep., 1928 | Kittredge.
| |
| 2989288 | Jun., 1961 | Smith.
| |
| 4641887 | Feb., 1987 | Klueting.
| |
| 4799403 | Jan., 1989 | Dinkel et al.
| |
| 4817463 | Apr., 1989 | Cameron.
| |
| 5127286 | Jul., 1992 | Wittig.
| |
| 5137073 | Aug., 1992 | Huang.
| |
| 5217278 | Jun., 1993 | Harrison et al.
| |
| 5704687 | Jan., 1998 | Klingler.
| |
| 5842944 | Dec., 1998 | Morishita et al.
| |
| 6086502 | Jul., 2000 | Chung.
| |
| 6179384 | Jan., 2001 | DeKraker et al.
| |
| 6254187 | Jul., 2001 | Schuster, Sr. et al.
| |
| 6364414 | Apr., 2002 | Specht.
| |
| 2002/0121802 | Sep., 2002 | McMillen.
| |
| 2003/0106970 | Jun., 2003 | McMillen.
| |
| Foreign Patent Documents |
| 141801 | Apr., 1920 | GB.
| |
Primary Examiner: Pang; Roger
Attorney, Agent or Firm: Husch & Eppenberger, LLC, Kang; Grant D.
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
APPENDIX
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is in the field of mechanical actuators for traction cables,
especially as applied to the control of ergonomic supports in seating, particularly
automobile seats.
2. Related Art
Ergonomic supports for seats, such as automobile seats, need to be adjustable.
Movement of the internal components of ergonomic supports, such as lumbar supports,
is often made by applying traction to a traction cable such as Bowden cable. The
ergonomic supports frequently require the application of traction under some tension
to overcome a static bias of a component and/or the weight of the seat occupant,
in order to bring the moving parts into an ergonomically weight supporting position
for the comfort of the passenger.
Traction cables such as Bowden cables are typically comprised of a wire
that slides axially through a sleeve. At the lumbar support, the wire will be attached
to one portion of a stamped metal or molded plastic pressure surface that is mounted
to arch into a supporting position when traction is applied to one or both of its
ends. The traction cable sleeve is attached to another portion of the pressure
surface, or the mount, to apply the traction. See U.S. Pat. No. 6,254,187, incorporated
by reference herein, for examples, of such components. Other components may slide
in and out of a channel in a housing, with the sliding being powered by the application
of traction through the Bowden cable wire. In such devices, the wire is attached
to the moving portion and the sleeve to a housing or mount. See U.S. Pat. No. 6,619,739,
incorporated by reference herein, for an example of these components. The present
invention may be applied to any moving parts that may be actuated by a traction cable.
The mounting of the traction cable on the components of the ergonomic device
require that the Bowden cable sleeve end be fixed to a portion of the ergonomic
support and the end of the wire that slides through the sleeve be attached to another
portion of the ergonomic support. An actuation device mounted at the other end
of the traction cable must be able to apply traction to pull the wire through and
from the sleeve and also must be able to hold the wire at a selected position along
its axial travel relative to the sleeve, in order to thereby hold the connected
ergonomic support in a position selected by the user.
Power actuators typically achieve these necessary functions by holding the
sleeve end in a fixed position and attaching the wire end to a moving part in order
to draw it from the sleeve. In some actuators the moving part is an axially translating
lead screw, see U.S. patent application Ser. No. 10/008,896, incorporated by reference
herein. In other actuators the moving part is a pulley having a seat for a wire
end bullet. Turning the pulley thereby pulls the wire from the sleeve.
In addition to the necessary functions recited above, there is a variety of traits
that are desirable in the marketplace for actuators that apply traction manually.
Among these are ease of use and a perception by the user that the components move smoothly.
Planetary gears applied to other applications are known. The equilateral
symmetry of the drive train is desirable for its mechanical advantage, which promotes
ease of use, and for its smooth application of power.
However, the planetary gear itself would not be capable of holding a selected
position against the tension applied to the traction cable by use of the ergonomic
support it is used to actuate.
There is a need in the art for a smooth, easy to operate planetary gear mechanical
actuator that is capable of holding a selected position. As always, there is a
continuing need in the art to produce components that are durable and economical.
SUMMARY OF THE INVENTION
It is in view of the above problems that the present invention was developed.
The present invention is a planetary gear mechanical actuator for a traction cable
having a locking spring.
A traction cable sleeve is mounted in a stationary position in a housing. The
traction
cable wire extends from the sleeve and into the housing where it is seated on a
pulley. The pulley is rotated by a planetary gear assembly.
A sun gear includes a fixed tab, flange or lever. A drive shaft turns the sun
gear.
The drive shaft also has a tab or boss disposed to articulate with the sun gear
flange or lever. The housing has a seat for a locking spring. The ends of the spring
are disposed against the lever or flange of the sun gear such that turning the
sun gear expands the spring. Expansion of the spring engages a spring seat in the
housing in a friction fit, locking the actuator and ergonomic support in a selected
position. The tabs on the drive shaft are disposed adjacent to the spring ends
in order to compress the spring and release the friction lock when the actuator
is turned in a reverse direction.
In one embodiment, the locking spring is a circular spring coaxial with the sun gear.
In one embodiment, a bearing and groove assembly provide a positive stop to prevent
overloading components at the end of a range of travel
Further features and advantages of the present invention, as well as the
structure and operation of various embodiments of the present invention, are described
in detail below with reference to the accompanying drawings.
Claims
What is claimed is:
1. A traction cable actuator comprising:
a sun gear, having a lever;
at least two planetary gears engaged with said sun gear;
a housing having a toothed race engaging said planetary gears, said housing further
having a lock spring seat, and said housing further having a traction cable sleeve seat;
a drive shaft operatively engaged with said sun gear to turn said sun gear, said
shaft having at least one release tab;
a pulley disposed within said housing, said pulley having planetary gear axles,
said axles being disposed to receive driving force from said planetary gears and
said pulley having a traction cable wire seat;
a lock spring disposed to engage said lock spring seat in said housing and to
engage said lever on said sun gear when said sun gear is turned;
whereby, said lock spring holds said pulley in a position selected by turning
said drive shaft.
2. The actuator of claim 1 wherein said a gear ratio between said sun gear and
said pulley is in the range of about 4.0 to about 4.5 to 1.
3. The actuator of claim 1 wherein said lock spring holds said pulley in position
by expanding against said lock spring seat in a frictional engagement, and by a
lock spring end abutting said lever of said sun gear.
4. The actuator of claim 1 wherein said release tab is disposed to abut an end
of said lock spring such that rotation of said release tab compresses said lock
spring in order to release it from a friction engagement with said lock spring seat.
5. The actuator of claim 1 further comprising a positive stop device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
None.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and form a part of the specification,
illustrate the embodiments of the present invention and together with the description,
serve to explain the principles of the invention. In the drawings:
FIG. 1 is an exploded perspective view of the planetary gear manual actuator
of the present invention.
FIG. 2 is an assembled, cut away, perspective view of the planetary gear manual
actuator of the present invention.
FIG. 3 is a perspective view of an assembled actuator.
FIG. 4 is an exploded view of an alternative embodiment of the actuator.
FIG. 5 is an exploded perspective view of the positive stop feature of the alternative embodiment.
FIG. 6 is a perspective view of the positive stop.
FIG. 7 is a perspective view of the positive stop.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the accompanying drawings in which like reference numbers
indicate like elements, FIGS. 1 and 2 are perspective views of the planetary gear
manual actuator of the present invention. FIG. 1 is exploded and FIG. 2 is assembled
and cut away. The housing
10 has attached to it or, in the depicted embodiment,
integrally formed as a part of it, Bowden cable sleeve seats
12. A key hole
slot
14 allows for assembly of the actuator with a traction cable. The interior
of the housing includes a toothed race
16. The recess
20 comprises
a seat for a locking spring. In the depicted embodiment, the recess is annular.
A seat for a pulley is substantially on a plane with the Bowden cable sleeve
seats
12 and key hole slots
14.
Pulley
30 is dimensioned to fit within the pulley seat in the housing.
The pulley has a slot
34 for receiving a traction cable wire (not shown)
as the pulley turns to apply traction to the wire. The pulley also has a seat
36
for a traction cable wire end bullet. The faces of this seat will contact the wire
end bullet and apply traction to it when the pulley is turned. The pulley also
has axles
32 for mounting of planetary gears
40 and for receiving
rotational force applied through them. Those with skill in the art will understand
that although three planetary gears and planetary gear axles are depicted in this
embodiment, any number of planetary gears and planetary gear axles are within the
scope of the present invention.
Locking spring
50 has a first end
52 and a second end
54,
each of which ends have a tab, bent end or other face for engaging other herein
described components of the actuator. Locking spring
50 is dimensioned to
seat in close cooperation with recess
20 in housing
10 when the spring
is in its relaxed state. That is, the dimensions of the spring and recess
20
are such that there is enough room for the spring to rotate, but insufficient room
for the spring to expand. The spring may actually touch the housing seat wall
20
when the spring is still relaxed, provided it can turn when not expanded. More
particularly, if ends
52 and
54 were forced apart outside the housing,
the overall diameter of spring
50 would enlarge. Inside the housing, though,
the recess
20 forestalls expansion of the spring
50 diameter. Accordingly,
recess
20 also forestalls a movement tending to separate a first spring
end
52 from second spring end
54.
Sun gear disk
60 includes a sun gear
62 and a lever, flange, tab
64 or other element having at least one face for engaging at least one end
(
52 and/or
54) of spring
50.
Drive shaft
70 includes a hub
72 configured to be assembled with
a handle
90 and, in operation, to receive rotational driving force through
a users turning of the handle
90. The drive shaft axle
74 proceeds
downward and through a central hole
66 in the sun gear disk
60. In
the depicted embodiment, drive shaft axle
74 includes a key rail
76
configured to fit into a key slot (not shown) in hole
66 and to apply driving
force to sun gear disk
60 via its engagement with sun gear disk hole
66.
Drive shaft
70 also has a disk
78. The disk
78 includes first
and second and tabs of flanges
80 disposed to straddle lever
64,
when assembled, and abut and engage ends
52 and/or
54 of spring
50.
The housing top
88 has mounting ears
86 for receiving pins or screws
92. Pins, screws, rivets or other known fixation devices are used to attach
the housing top
88 to housing
10 and thereby encapsulate the other
operative components within the assembled actuator in functional relationship to
one another. In assembly, handle
90 is inserted through a central hole in
the housing top
88 to receive its friction fit with drive shaft hub
72.
To be assembled with a traction cable, (not shown) the traction cable sleeve
is
mounted on sleeve seat
12 and the traction cable wire is extended and fit
through a key hole slot
14 so that the wire end bullet may be placed in
wire end bullet seat
36 such that the wire may be received into pulley slot
34. This is done after assembly of the actuator components
10-
90.
During assembly with an ergonomic support, traction cable will be mounted
on the ergonomic support when the ergonomic support is in a rest position. At the
actuator, the Bowden cable wire end bullet will be mounted with both the locking
spring
50 and the lumbar support in a rest or untensioned position.
The planetary gears
40 are mounted on axles
32 to engage with toothed
race
16. Thereafter spring
50 is seated in recess
20. The
sun gear disk
60 is installed on top of this assembly so that sun gear
62
engages planetary gears
40. Also, sun gear lever
64 is disposed between
the ends
52 and
54 of spring
50. The drive shaft axle
74
is inserted into the sun gear disk
60. The drive shaft disk
78 is
disposed such that tabs
80 descend downward into the plane occupied by the
sun gear lever
64 and spring
50. Whether aligned by a key (
76)
or not, tabs
80 straddle the lever
64 and ends
52 and
54
of the spring
50. In this manner, each end
52 and
54 of spring
50 is sandwiched between a side face of lever
64 and one of the tabs
80, in close cooperation with them and with a small amount of tolerance.
Assembly is completed by screwing the housing top
80 on the housing bottom
10 and installing lever
90.
As can be seen, the actuator as a whole and the traction cable mounting aspects
of it are bilateral and symmetrical. Accordingly, the actuator may be used an either
right or left handed seating, may be used for differing ergonomic supports on the
right or left hand side of the same seat or may for any other reason receive mounting
of a single traction cable on either side of housing
10. A unilateral version
with only one tab
80 is within the scope of the present invention.
In operation, a user will adjust the ergonomic support, for example a lumbar
support,
from a rest position to a selected position by turning handle
90. Turning
handle
90 turns drive shaft
70, which turns sun gear
62. The
sun gear's engagement with planetary gears
40 causes them to rotate in an
encapsulated path defined by the toothed race
16. Planetary gears
40
will in turn move in a circular path, causing pulley
30 to rotate. The rotation
of pulley
30 in a first direction will apply tension to draw a traction
cable wire out of a traction cable sleeve, causing a corresponding traction at
the other end of the traction cable to actuate an ergonomic support. The depicted
embodiment has a gear ratio of 4.3 to 1, whereby the pulley
30 turns once
for 4.3 turns of the handle
90. Three handle turns would yield 230°
of pulley turn, corresponding to a traction cable range of travel of about 30 to
about 50 millimeters, which is a common range of travel for auto seat ergonomic
supports. This gear ration imparts a desirable ease of use to the actuator.
As the sun gear rotates to bring an ergonomic support into a selected position,
the lever
64 and disk
78 rotate. Because the ends
52 and
54
of spring
50 are adjacent to lever
64, the spring
50 will
rotate in unison with the sun gear disk
66 and the drive axle disk
78.
As rotation continues, tension increases on the traction cable and tends to pull
pulley
30 tangentially back towards its original position. When the user
releases handle
90, in a selected position, this tractive force on the wire
and counter rotational force on the pulley will need to be resisted if the selected
position is to be held. After a users release, this force will be transferred through
the planetary and sun gears to sun gear disk
66 and its lever
64.
This force will be exerted by lever
64 on the spring end closest to the
neutral position, which in the depicted embodiment is spring end
52. However,
such a force on spring end
52 will tend to cause an expansion of the spring
50. As described earlier, expansion of spring
50 is arrested by the
housing wall in circumference around recess
20. The counter rotational force
of the wire that expands the spring holds it in a friction fit with the housing
seat. The device locks in the selected position.
The opposite spring end,
54 in the depicted embodiment, is not also pushed
in a counter rotating direction by the tab
80 because a small amount of
play or space is dimensioned between them. This space, although remaining quite
small, is slightly larger than the amount of circumferential space necessary to
move spring
50 into locking engagement with recess wall
20. The locking
effect of spring
50's expansion against the recess wall
20 correspondingly
holds lever
60 in place and prevents its counter rotation. Accordingly,
sun gear
62, planetary gears
40 and pulley
30 are all prevented
from counter rotation. Thus, the user selected position is held in place against
the tension on the traction wire being exerted in a returning or counter rotational direction.
To release the selected position and return to a home position, the drive shaft
is turned in the opposite direction. Release tab
80 then closes the small
space between itself and spring end
52 or
54, and pushes it. This
contracts spring
50, releasing it from locking engagement with spring seat
wall
20, so that the spring can counter rotate towards the home position
in conjunction with lever
64 and disk
78.
FIG. 3 depicts an assembled alternative embodiment of the planetary gear actuator.
As can be seen through key hole slot
122 in lower housing part
110,
the pulley
130 and its wire end bullet seat
136 are visible and accessible
for assembly with a traction cable. The upper housing component
188, has
ribbing molded into it for increased strength.
FIG. 4 depicts an exploded view of alternative embodiment of the actuator in
the present invention. Components
110 through
154,
172,
178,
188 and
190 all correspond to the equivalent components
10
through
54, etc. in FIGS. 1 and 2. Their configuration, assembly, function
and operation are the same. Disk
178 also has tabs on its underside for
engaging spring end
152 and
154, however from the perspective of
FIG. 4 they are obscured by the top of disk
178. FIGS. 4,
5,
6
and
7, also disclose a further novel feature of the present invention. It
is a positive stop mechanism comprised of a spiral or helical groove
204
in which is disposed a ball bearing or other traveling component
202. When
assembled, bearing
202 is held in groove
204 by the sandwich assembly
of disk
178 with a housing top
188. Component
202 may be a
convexity in top element
188, on its bottom side.
As described above, several turns of the actuator may be required to move an
ergonomic
support through its entire range of motion, as in most anticipated installations
of the present invention. At either terminal end of the ergonomic support's range
of motion, continued turning of the handle
190 by a user may lead to unnecessary
stress and tension on the components, and possibly an imprecise feel to the users
touch. A positive stop incorporated in the actuator itself eliminates those effects.
Accordingly, in the depicted embodiment, the number of turns (3) of the spiral
groove
204 correspond to the number of turns of the hand crank
190
required to take the ergonomic support anticipated to be actuated by the present
invention through its entire range of motion. Other degrees of rotation of the
spiral groove, other groove configurations and other ranges of travel are within
the scope of the present invention.
Such positive stop, when used with a high speed gear train such as the planetary
gear, will reduce the load in the gear train. As an example of this protective
capacity, the depicted embodiment has a gear ratio between the sun gear and pulley
of 4.33 to 1. This means that the torque received at the pulley (
30,
130)
is 4.33 times that applied to handle (
90,
190). For the depicted
manual system, the minimal requirement for this torque 8 Nm. The presently depicted
planetary gear train would amplify this to 34.64 Nm (4.33 times 8). When the components
are made of plastic, that load is sufficient to damage each of the components if
applied after the end of a range of travel is reached. The positive stop depicted
in FIGS. 4-7, prevents this magnified load from being applied to the subsequent
portion of the gear train, and leaves them under the stress of only the ergonomic
support, as they are designed to withstand.
The positive stop system comprised of bearing
202 and groove
204
in the top surface of disk
178 may also be applied for actuators powered
by electric motors. Alternatively, the groove may be in the bottom surface of a
top element, e.g.
188, engaged with a top surface of a bottom element, e.g.
178. Again, the effect of these is to reduce the load on the components
and increase their durability and prolong their usable lifetime.
The positive stop feature may be incorporated with other actuators, especially
rotational and/or coaxial pulley type actuators. The stop feature may be used with
electric motors used as force actuators. FIG. 6 schematically depicts an electric
motor
300 and motor housing and geared transfer assembly
302, which
are conventional features in known actuators.
In view of the foregoing, it will be seen that the several advantages of the
invention
are achieved and attained.
The embodiments were chosen and described in order to best explain the principles
of the invention and its practical application to thereby enable others skilled
in the art to best utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated.
As various modifications could be made in the constructions and methods herein
described and illustrated without departing from the scope of the invention, it
is intended that all matter contained in the foregoing description or shown in
the accompanying drawings shall be interpreted as illustrative rather than limiting.
Thus, the breadth and scope of the present invention should not be limited by any
of the above-described exemplary embodiments, but should be defined only in accordance
with the following claims appended hereto and their equivalents.
*
