CA1162864A

CA1162864A - Mechanical lock

Info

Publication number: CA1162864A
Application number: CA000368954A
Authority: CA
Inventors: Clyde R. Porter
Original assignee: PL Porter Co
Current assignee: Hydro Aire Inc
Priority date: 1980-06-06
Filing date: 1981-01-21
Publication date: 1984-02-28
Also published as: IT8121662A0; AU6957181A; GB2078846A; ES500493A0; JPS6239773B2; SE8100984L; DE3103698C2; GB2078846B; JPS5725017A; AR226455A1; BR8100211A; ZA81481B; IT1137011B; ES8204363A1; FR2484032B1; FR2484032A1; BE887665A; SE446764B; DE3103698A1

Abstract

MECHANICAL LOCK
ABSTRACT OF THE DISCLOSURE
A mechanical lock normally preventing axial motion of a rod with respect to a housing sleeve that surrounds the rod includes a coil spring whose diameter is slightly less than the diameter of the rod so that the coil spring normally encircles and grips the rod tightly. The coil spring is mounted on the rod between a bushing fixed to the housing sleeve at one end of the spring and a second bushing that is rotatable with respect to the housing at the other end of the spring. The rotatable bushing is rotated by an actuating lever to unwind the spring so as to increase its diameter and thereby to release its grip on the rod. Both the fixed bushing and the rotatable bushing include beveled faces which permit the last few turns at both ends of the spring to become cocked on the rod to provide a true locking engagement with the rod. The last few turns of the spring adjacent the rotatable bushing are immediately released by a minimum of rotation of the bushing since it is not necessary for the unwinding of the spring to be transmitted through the entire length of the spring. Because the spring is shorter than in prior locks, the entire device is shorter and accordingly more resistent to bending and lighter in weight. The structure of the device simplifies its assembly and this, along with its reduced length appreciably reduces the cost of producing the device.

Description

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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.

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 32 /// ;

. '' . .' 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.

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. '' 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.

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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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.

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 ~ q~28~

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.

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. . ~ . .-.

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 -~.

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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 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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~6Z864 ' :
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 - . , .

,' -~ -..

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 ~-;
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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 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.

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 ., .............. : . . ...
~ the scope of invention.
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Claims

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:-

1. As an article of manufacture, a mechanical friction lock for normally preventing axial motion of a rod with respect to a housing and for selectively permitting such motion when unlocked by an operator, said mechanical friction lock comprising: .
a fixed member;
a coil spring;
a rod extending coaxially through said coil spring, the diameter of said rod being slightly larger than the inside diameter of said coil spring when it is not mounted on said rod, so that said coil spring normally grips said rod tightly when mounted on said rod;
retaining means affixed to said fixed member for preventing motion of a first end of said coil spring with respect to said fixed member;
release means engaging a second end of said coil spring for facilitating rotation by an operator of said second end of said coil spring with respect to said first end of said coil spring to slightly unwind said coil spring, causing it to increase in diameter and thereby to release its grip on said rod, whereby said rod can be moved axially with respect to said fixed member, and said release means further including a surface inclined at an acute angle with respect to the axis of said coil spring and so located as to contact a portion of the last coil at the second end of said coil spring, whereby an axial load on said rod will cause said last coil to become cocked so as to grip said rod more tightly.

2. The mechanical lock of Claim 1 wherein said retaining means further comprise a surface inclined at an acute angle with respect to the axis of said coil spring and so located as to contact a portion of the last coil at the first end of said coil spring, whereby an axial load on said rod will cause said last coil to become cocked so as to grip said rod more tightly.

3. The mechanical lock of Claim 1 wherein said retaining means is a bushing through which said rod extends axially.

4. The mechanical lock of Claim 1 wherein said fixed member is a hollow cylinder.

5. The mechanical lock of Claim 4 wherein said retaining means is a bushing affixed within said hollow cylinder.

6. The mechanical lock of Claim 1 wherein said release means further comprise a bushing that is rotatable with respect to said rod and with respect to said fixed member.

7. The mechanical lock of Claim 1 wherein said housing includes a window, said release means including a rotatable bushing; and, operator means extending through said window to effect rotation of said bushing.