Note: Descriptions are shown in the official language in which they were submitted.
116~
1 MEC~NICAL LOCK
6 The present invention is in the field of mechanical
7 locking devices and specifically relates to a device of the
8 type in which the locking is effected by a coiled spring which
9 grips a rod, for clamping the rod against translational
motion relative to a housing and for selectively enabling
11 such motion.
12
13
14 Friction brake locking devices are known in which a rod
extends into a cylindrical housing. Normally, the rod is
16 locked with respect to the housing so that axial transla-
17 tional motion of the rod relative to the housing is prevented.
18 However, the device can be selectively actuated to an unlocked
19 state in which such motion is enabled. A coiled spring is
affixed to the housing and is coaxial with the rod in the
21 locked state. The spring grips the curved surface of the rod
22 to prevent the rod from moving with respect to the housing.
23 An actuation lever permits an operator to partially unwind
24 the spring, thereby increasing its inside diameter so that
the spring no longer grips the rod, which may then be moved
26 freely axially within the coiled spring.
2~
28 The use of a coiled spring to grip a rod extending co-
29 axially through the spring is well known. A number of
locking devices making use of this basic principle are
31 kno~m in the art.
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1 Among the prior art devices is the lockin~ device of
2 U.S. Patent No. 3,249,180 issued May 3, 1966 to Torossian.
3 As shown in Figure 10 of the Torossian patent, the spring
is affixed at one end to a fixed ring 109, while the other
end of the spring 108 is engaged by a rotatable ring 110.
~ The ring 110 engages a longitudinally-extending groove in
7 the rod, so that when the rod is rotated, the ring also
8 rotates to tighten the grip of the spring on the rod.
The device of the Torossian patent includes an abutment
11 on the rotating ring and on the fixed ring to cause the
12 spring to become cocked on the rod, in which state the
13 gripping force of the spring on the rod increases with the
14 axial load, thereby resulting in a true locking action. This
aspect of the mechanics of the device was also-recognized by
16 Howell in U.S. Patent No. 2,750,994 issued June 19, 1956.
17 However, as shown most clearly in Figure 5 of the Howell patent,
1~ in his device, only the fixed sleeve 25 is providPd with a
19 beveled base 40, and the device is actuated by rotating the
opposite end 31 of the spring. Accordingly, in Howell's device,
21 it is necessary to unwind the many turns of the spring to trans-
22 mit the enlargement of the diameter to the fixed end of the
23 spring. This necessitates an unnecessarily long stroke for
24 the actuating lPver.
26 Another type of prior art device is that shown in U.S.
27 Patent No. 3,87~,480 issued April 1, 1975 to Porter,,et al.
28 As can best be seen in Figure 2 of the Porter, et al. patent, -
29 two springs are disposed co-axially to extend in opposite : -
directions from a central actuating lever to fixed locking
31 bushings located at opposite ends of a housing sleeve. One
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1 of the locking bushings locks the device in tension and the
2 other locks it in compression. The interaction of the last
3 two or three coils at the ends of the springs distal to the
4 actuating lever with the lockiny bushings is responsible for
the locking effect.
7 It is noteworthy that while only one of the springs in
8 the Porter, et al. device is effective at a particular instant
9 to oppose tension or compression, unlockin~ of the device
nonetheless requires unwinding both springs simultaneously by
11 use of the actuating lever. The lever must be moved through
12 a sufficient stroke that the entire length of each spring is
13 unwound, to ensure that the last two or three turns will be
14 - unwound. This necessitates a large actuating lever stroke
which is opposed by the combined forces of both springs re-
1~ sisting unwinding. Consequently, in contrast to the present
17 invention both the actuating lever stroke and the force needed
18 for its operation are relatively large. ~hile such structure
19 functions well, there are installations where, due to space
limitations and the like, there is a need for a friction brake
21 type of device in which the stroke of the actuating lever is
22 comparatively small and which operates at a comparatively
23 smaller force.
24
The structure of the Porter, et al. device, while satis-
26 factory in pexformance,is somewhat complicated because of
27 the assembly of the device. The end bushings which affixed
28 the distal encls of the springs to the housing sleeve had to
29 be rotated during the assembly process to positions in which
the proximal ends of both of the springs abutted the actuating
31 lever in a balanced manner. Such rotation necessitated that
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1 the grip of at least one of the springs be released by un-
2 winding that spring. In practice, assembly required a
3 highly-skilled wind-up operation to assure that both springs
4 were properly compacted and twisted against the actuating
lever. In contrast, in the present invention this compli-
6 cated assembly procedure is ~ot required.
8 The following patents carl be distinguised from the
9 present invention on the basis that they do not include an
abutment or beveled bushing against which the spring bears,
11 and accordingly the true locking action discussed above is
12 not employed. These patents include U.S. Patent No. 2,434,480
13 to Anderson, issued January 13, 1948; U.S. Patent No. 3,320,5~5
14 to Kedem; U.S. Patent No. 2,429,383 to ~rens, and U.S. Patent
No. 3,064,766 to Hanizeski. ''
16 -
17 There are instances in which it is desirable to have a
18 mechanical locking device in which the force ~eeded to release
19 the lock mechanism is reduced while also reducing the amount
of movement of the actuating lever to effect release.
21 typical such application is in the automotive seat field in
22 which movement of the seat back between an upright and reclining
23 position should be accomplished smoothly and without a snap
24 type action. Further, where the locking mechanism is of the
direct control actuation type, i.e. the user manipulates a ~
26 release lever, in contrast to some type of linkage mechanism
27 of the remote control type, large force~ for release or large
28 movements of the actuating lever should be avoided.
29
While the above may be accomplished, one of the practical
31 considerations is to accomplish these objectives with a rela-
32 tively inexpensive device, but one which is capable of func- ¦
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1~1621364D
tioning properly over an extended period of time. Further,
2 the device should be essentially maintenance free and
3 capable of functioning over extreme temperature ranges and
4 not adversely affected by water, dirt, dust and the li~:e~
8 In accordance with the present invention, the above-
9 described disadvantages of the prior art mechanical locks are
overcome by the improved structure to be described and which -
11 represents a preferred form of the invention. This structure
12 of the invention includes only a single spring instead of the
13 two springs used in the Porter, et al. patent, thereby immedi-
14 ately reducing the actuating force by half.
- - ~ -
16 - In accordance with the present invention, a stationary
17 - locking bushing is provided at one end of the single spring
18 and a rotatable locking bushing is provided at the other end
19 of the spring. The spring inieracts with these locking
bushings to prevent motion of the rod in either axial airec-
21 tion. The rotatable locking bushing is turned by an actua~
22 ting lever, and since the last two or three coils of the
23 spring that are effective for locking the rod in one direc-
24 tion are adjacent the rotatable locking bushing, it lS not
necessary to unwind the entire spring to release the grip of
26 those coils. Thus, the release action is smooth because the
2~ balance of the spring tends to act as a drag thereby avoiding
28 a snap release action and the sudden motion which normally
29 accompanies a snap action release. Accor~ingly, these coils
can be released by only a short stroke of the actuating lever.
31 Thus, the present invention makes possible a mechanical lock
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1 that requires less force and less stroke to release while
2 assuring a smooth release. These features make practical
.
3 the use of a direct control actuation push-button type of
4 control for operating the actuating lever. The use of a
bush-botton control is very desirable from an aesthetic
6 or styling standpoin~. -
- ,~
8 A further feature is the location o~ the actuating
9 lever in a position other than in the area of the spring.
The opening through which the lever extends is covered to
11 prevent intrusion of dirt, soap or cleaning solutions,
12 especially in the area of the locking zone between the
13 few coils of the spring and the rod. The interior of the
14 device is packed with a high temperature range grease of
the aircraft or automotive type, and is with a type which
16 does not flow at high temperature.
17
18 Less apparent, but also important, is the simplification -
19 of the assembly process that results from the structure of
the present invention. Unlike the mechanical lock described
21 in the Porter, et al. patent, the parts of the present
22 invention can be assembled along the rod, inserted into the
23 housing sleeve, and then affixed to the housing sleeve by
24 swaging the fixed locking bushing inside the sleeve.
26 Because the spring in the preseDt invention is short~r
27 than the springs used in the device described in the Porter,
28 et al. patent, the entire mechanical lock is shorter. The
29 length-to-diameter ratio is correspondingly less, and this
. :
improves the ability of the device to resist bending while
31 allowing higher unit loading because of the shorter column
.. . . .. ..
32 length.
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Because the entire mechanical lock is shorter and be-
cause its assembly procedure is simpler, the mechanical lock
of the present invention can be produced at a cost tha~ is
approximately half that of the prior art mechanical lock.
The mechanical lock of the present invention is appreciably
lighter in weight than the prior art lock, which makes the
lock of the present invention better suited for aircraft and
automotive use.
A preferred embodiment of the invention is illustrated
by way of example in the drawing. It is to be expressly
understood, however, that the drawings are for the purpose
of illustration and descriptlon only and are not intended as
a definition of the limits of the invention. In the drawings:
Figure 1 is a view, partly in section and partly in
elevation, showing a preferred embodiment of the mechanical
lock of the present invention; and,
Figure 2 is an exploded view, with some parts in section,
of the mechanical lock shown in Figure 1.
Turning now to the drawings in which there is shown a
preferred embodiment of the present invention, it can be
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1 seen that the mechani.cal lock 10 includes a cylindrical ..
2 rod 12 which is selectively slideable along an axis 13
3 within and relative to a housing 14 which may be tubular
4 as shown.
Normally the rod 12 is locked at a fixed position
7 axially with respect to the ;housing 14, and this relation-
8 ship is interrupted only when an operator moves an actua-
9 ting lever 16 to unlock the device to permit the rod 12 to
be shifted axially to a new position with respect to the
11 housing 14.
12
13 The mechanical friction lock 10 shown in the drawings .
14 may be used in positioning the back of a sPat, of the re-
clining type commonly used in passenger airplanes, railroad
16 coaches and automobiles. The mechanical lock is provided
17 with a mounting 18 and a trunnion 20 for use in attaching the
. .
18 mechanical lock to certain portions of the seat. ~he portion
19 of the mounting received within- one end of the housing 14
includes a groove 21 which is used to swage the housing to
21 the mounting, as shown_ A stop 22 provides a positive limit
22 to the amount of motion of the rod 12 with respect to the
23 housing 14, the other end of the rod may include an eye 23
24 or any other form of device for attachment to a cooperating .
- . , . . ,, - ~ . .
. 25 component of the seat. . ~ . .-.
26
27 Located axially of the rod, within the housing and
2~ ad~acent to the mounting 18 is a rotatable bushing Z4
29 while at the other end of the housing is a second bushing 26
which includes a groove 27, similar.to 21, used to swage the
31 housing 14 to the fixed bushing-26. Rotatable bushing 24- ..
32 may include a groove 28 provided along the outer perlphery -~.
- ~6~
1 to receive the end of the lever as shown.
3 Surrounding a portion of the rod and located between
4 the rotatable and fixed bushinqs 24 and 26, respectively,
~ is a helical coil spring 30, each end of which includes a
6 radially extending tang 31 and 32. Bushing 24 includes an
7 axial slot 34 to receive tang 32 ~7hile fixed bushing 26
8 includes an axial slot 36 to receive the other tang 31.
9 Thus, one end of the spring is fixed against rotation while
the other end may be rotated. -
11 - . : ''
12 In the normal at-rest seat position of the lever 16,
13 the spring 30 is in frictional engagement with the periphery
14 with the rod 12 to lock the rod in a fixed position axially
with the housing 14. Upon movement of the actuating lever 16,
16 the rotatable bushing is rotated and the spring 30 is unwound - ;
17 causing it to release its grip on the rod 12. Depending upon - -
18 the direction -in which the spring 30 is wound, release movement ~
19 o the lever 16 may be up or down, as viewed in the drawings,
to rotate bushing 24 in one or the other direction to effect
21 release of the rod 12. When released, the lever 16 returns
2Z automatically to the locked position and the spring friction-
23 ally engages the periphery of the rod 14.
24 ; ;
The rotating bushing 24 includes a beveled face 38, and
26 the fixed bushing 26 includes a beveled face 39. These
27 beveled faces cause the last few coils at the ends of the
28 spring 30 to become cocked against the rod 12 thereby locking
29 it with a true locking action in tension and compression
respectively. The locking engagement referred to herein 7
31
32
1 is a type of interaction in which the application of in- ..
2 creased force results in the parts becoming more securely
3 locked together. . ;~
4 - . .
A sleeve 40 may surround the spring 30 to insure that
6 as the spring is unwound by motion of the xotatable bushing
8 24 the slack of the spring will be transmitted to the end
of the spring held by the fixed bushing 26 rather than being
9 accumulated in the turns nearest the rotable bushing 24.
l~hile the form illustrated includes a sleeve 40, one variant
11 which may be used is to increase the axial length of each l
12 of the bushings 24 and 26 so that the respective inboard ends .
13 or skirts of the bushings meet.- In this way the sleeve.40. -
14 is not needed since the extended bushings now perform the ;:..
function of that sleeve_ One advantage of this variant is
16 that better bend resistance is provided along the axis of the
. 17 housing. ; ~
19 In the form illustrated, a collar 42 with two spaced
fingers 43 and 44 fits over the housing 14. The fingers 43_
21 and 44 may be affixed to the lever 16, as by welding or the
22 like, so that as the lever is actuated, the collar 42.rotates
23 relative to the housing 14.
24 . -
.
The housi.ng 14 lncludes a window 45 through which the ~ ;
26 lever 16 extends into slot 28.. of bushing 24. Since the
27 collar 42 moves with the lever, it functions as a cover for
,. ~ , , . ~ .
~8 the window to prevent dust and other foreign materials from
29 entering the housing through window 45. . . -;. .
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As mentioned earlier, the inside of the housing between
j 2 the end mounting 18 and bushing 26 is packed with lubricant
J 3 such as a high temperature stable grease which will not flow
at elevated temperatures. Thus, one function of the collar
42 is to assist keeping the grease within the housing.
It will also be noted that the window 45 is located in
alignment with the slot 28 of the bushing 24, rather than in
an area opening into the spring region. As a practical
matter is is quite difficult for foreign matter to enter the
12 housing through the window and to move between the outer
periphery of bushing 24 and the facing inside wall of the
3 housing into the locking region of the spring. This has ;
definite practical advantages over prior art structure,
especially for locking devices used in the au~motive field.
17 In operation, only a relatlvely small amount of movement .
8 of the lever 16 is needed in order to effect release of~the ^~
rod 12, as is apparent from the relatively small circumfer-
ential size of the window 45. Further, since one spring is
22 used, fixed at one end and moveable at the other, the amount
23 of force needed is reduced. The reduction in force is also
attributable to the fact that the effective locking c~ils
- 24 of the spring 30 are those first 2 or 3 coils adjacent to
the rotating bushing 24. To achieve this type of
26 locking, the bushings include the angular faces 38 and 39
27 which produce the action described. The result is that
there tends to be an immediate and progressive release by
a small amount of rotation of the bushing 24, i.e. it is
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1 not necessary to transmit the motion throughout the entire
2 length of the spring 30. The action is that of a gradual
3 type release as the f1rst few coils of the spring unwind, '.7'.
4 with the balance of the spring acting as a drag for smooth
release of the rod 12~ In practical terms, the elimination
~ of the initial, snap quick release, with the resulting
7 sudden motion, is of definite advantage.
9 The structur~ of the present invention as shown in the
drawings simplifies the assembly of the mechanical lock. The
11 fixed bushing 26, the rotatable bushing 24, the spring 30, the
12 sleeve 40, and finally, the fixed bushing are slid onto the rod ;-~
13 in succession, the rotatable bushing 24 and the fixed bushing '
14 26 being rotated until the tangs 21, 32 of the spring 30 enter ''-;
the slots 36, 34. Thereafter, the housing 14 is slid over
16 the other parts on the rod and swaged to the end mounting'18
17 and the fixed bushing 26. Thereafter, the actuator 16, and~
18 the stop 22 and collar 42 are affixed to the mechanism.~
19 During the assembly, grease is also introduced into the assembly, '-'
but prior to the assembly of the collar.
21 ' - ' -'\'
22 Thus,' there has been described a mechanical friction lock I'~;~
23 having a structure which permits the lock to be unlocked by use ~-;
-. ~, :.
24 of an actuating lever in which the stroke and the actuating '- '
-
force are significantly reduced in comparison with'mechanical
26 locks of the prior art. The device uses a rotatable locking
27 hushing that is turned by the actuating lever and because the - .
28 two or three coils of the spring that are effective for locking
29 the rod in one direction are adjacent the rotatable locking
bushing, it is not necessary to unwind the entire spring to
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1 release the grip of those coils to permit motion in that
2 direction. The reduced stroke and actuating force of the
3 mechanical lock of the present invention make practical the
4 use of a airect control push-button actuation for operating
the lever. The use of a push-button control is very desirable
6 from a styling standpoint. The assembly process is simplified
~ by the structure of the lock of the present invention, and
8 this, along with the reduced length of the devices makes it
9 - possible to manufacture the present invention at a cost approx-
imately half that of prior art devices. Further, the advan-
11 tageous length-to-diameter ratio of the present invention
12 enhances the ability of the device to resist bending. Because
~ ^ . ..
v the mechanical lock of the present invention is appreciably
14 lighter in weight than prior art locks, it is better suited
for aircraft and automotive use.
16
17 The foregolng detailed description is illustrative of ':~'
18 one embodiment of the invention, and it is to be understood
19 that additional embodiments thereof will be obvious to those
2Q skilled in the art. The embodiments described herein together
21 with those additional embodiments are considered to be within
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~ the scope of invention.
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