US3869888A

US3869888A - Lock

Info

Publication number: US3869888A
Application number: US432693A
Authority: US
Inventors: Kenzo Yoshizawa
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-11
Filing date: 1974-01-11
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A lock includes a rotary shaft inserting a single key having first and second engagement elements, and first and second mating engagement members arranged around said rotary shaft. The first rotation of said single key together with the rotary shaft through an angle causes said first engagement element to engage with said first mating engagement member thereby making preparation for unlocking, and the subsequent rotation of said key through a certain angle causes said second engagement element to engage with said second mating engagement member so that the actual unlocking is effected. The lock also includes engagement prevention-cancelling means operatively connected to said two mating engagement members in such a manner that the engagement between said second engagement element and its mating engagement member becomes possible only when the unlocking preparation action takes place.

Description

United States atent n91 Yoshizawa Mar. 11, 1975 1 LOCK [76] Inventor: Kenzo Yoshizawa, 48-3 Kitamachi Minami, Chudoji, Shimogyo-ku, Kyoto, Japan [22] Filed: Jan. 11, 1974 [21] Appl. N0.: 432,693

[52] US. Cl. 70/355, 70/401 [51] Int. Cl. E05b 21/00 [58] Field of Search 70/150, 15] R, 152, 151 A,

Primary Examiner-Robert L. Wolfe Attorney, Agent, or Firm-Morgan, Finnegan, Durham & Pine [57] ABSTRACT A lock includes a rotary shaft inserting a single key having first and second engagement elements, and first and second mating engagement members arranged around said rotary shaft. The first rotation of said single key together with the rotary shaft through an angle causes said first engagement element to engage with said first mating engagement member thereby making preparation for unlocking, and the subsequent rotation of said key through a certain angle causes said second engagement element to engage with said second mating engagement member so that the actual unlocking is effected. The lock also includes engagement prevention-cancelling means operatively connected to said two mating engagement members in such a manner that the engagement between said second engagement element and its mating engagement member becomes possible only when the unlocking preparation action takes place.

6 Claims, 18 Drawing Figures ya; i4 7 id! 277/5214 54 .ffl

[IV/l [All 255 f .754 T9 2 1/ 0 f7 274 255;,

77d 0 o o PATENTEDHARI 1 7 869 888 SHEET 3 9 5 "i i-W LOCK BACKGROUND OF THE INVENTION The present invention relates to a new and improved lock which is locked by a special system completely different from the conventional system.

It is an object of this invention to provide a new and improved lock which can be unlocked only by a specific key and is protected against unauthorized unlocking by any or false keys.

An another object of this invention is to provide a new and improved lock which can be modified in almost innumerable ways.

A further object of this invention is to provide a new and improved lock which is possible to fabricate a wide variety of locks that require their respective different keys, by using the same constituent members.

SUMMARY OF THE INVENTION Briefly stated, the lock according to the present invention is constructed in such a manner that the unlocking operation is carried out in two steps, namely the first step of preparing for unlocking and the second step of the actual unlocking. In order to carry out these two operations, the present lock includes a single key having first and second engagement elements, a rotary shaft having longitudinal grooves (or keyholes) adapted to receive both engagement elements of the key, and first and second mating engagement members arranged around the rotary shaft. The first turning of the key inserted into the keyholes of rotary shaft through a given angle results in making preparation for unlocking with first mating engagement member being engaged by first engagement element, and the subsequent turning of the key together with the rotary shaft through a certain angle causes second engagement element to engage with second mating engagement member thereby effecting the actual unlocking. Thus, in the lock of the present invention, it follows that the unlocking is completed, as a whole, by a continuous turning movement of the key.

The lock has engagement prevention-cancelling means operatively connected to mating engagement members for enabling the second engagement element to be engaged with its mating engagement member only when the abovementioned unlocking preparation action in the first step takes place. This means serves to prevent unauthorized unlocking by using a false key as much as possible. Further, there is provided in the present lock unlocking operative means operatively connected to the mating engagement member associated with second engagement element in such a manner that it is actuated upon engagement of second engagment element with its mating engagement member.

In the present invention, the mechanism for making the preparation for unlocking in the first step is specially arranged to further ensure the prevention of anauthorized unlocking by false keys and to make it possible to fabricate a wide variety oflocks which can be unlocked only by their particular respective keys. That is, the member engageable with the key to make preparation for unlocking consists of several engagement element loosely fitted over a single central shaft and placed one upon another, the arrangement being such that only when the positional relation between these elements takes a particular phase, the preparation action effectively takes place. As for the relative phase of these elements, the shapes, or positions i are, selected with respect to the phase necessary for said preparation to effectively take place sov that theymay respectively take different positions. By the use of a key of particular shape, an element at the position of a ridge or recess of the key is given an amount of displacement related to the extent of such ridge or recess, whereby all the elements are aligned with respect to the phase for the predetermined unlocking preparation action. In the lock according to the invention, therefore, by changing the order in which the elements are placed one upon another, the shape of the key engageable with them can be changed in innumerable ways. This means that by using the same constituent members, it is possible to fabricate a wide variety of locks which require their respective different keys, such locks being suitable for mass production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 10 illustrate an embodiment of the lock according to the present invention, and FIG. Ila and 11b illustrate a modification of the lock of the present invention;

FIGS. 1, 2 and 3 are a front view, a rear view and a side view respectively, showing the external appearance;

FIG. 4 is a front view in partial section showing the lock in its locked condition;

FIGS. 5a, 5b, 5c, 5d, 5e and Sfare front views, in partial section, of the principal portions, explanatory of the unlocking operation which proceeds in the order a, b, c, d, e and f;

FIG. 6 is a front view, in partial section, showing the completion of the unlocking operation;

FIGS. 7a and 7b are assembly views of mating engagement members engageable with the engagement elements of the key, with b taken in the direction of arrow A in a;

FIG. 8 is an exploded plan view of the constituent parts of the mating engagement member engageable with the first engagement element of the key;

FIG. 9 is an exploded plan view of the constituent parts of the mating engagement member engageable with the second engagement element of the key;

FIGS. 11a and 11b are front views, in partial section, of the principal portions, showing the locked and unlocked conditions respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS By reference to the drawings showing the preferred embodiments of the invention, the concrete construction will now be made clear while explaining the actions, particularly unlocking action.

FIG. 4 shows a lock emboding the present invention in its locked condition, with the front plate 22 of a lock case 20 removed, the view being shown in partial section. As shown therein, the right-hand side projection 34 of a locking piece 32 slidably held on the rear plate 24 of the lock case 20 to be later described engages one end 30 of the U-shaped or fork-shaped portion of the lock piece 28, thereby holding the lock piece 28 immovable within the lock case 20 against the force of the spring 36.

The unlocking operation is effected by inserting a key 350 shown in FIG. 10 into a rotary shaft 38 from the side of the rear plate 24 and turning the key together with the rotary shaft 38 clockwise. The rotary shaft 38 rotatably extends from the rear plate 24 to the front plate 22 and as shown in FIGS. 2, 3, 4, 5, 6, etc., it is formed with

parallel grooves

40 and 42 at positions different in phase, substantially 180, with respect to the axis.

On the other hand, the key 350 is fork-shaped, having two flat

parallel legs

352 and 354 adapted to be insertable into the

longitudinal grooves

40 and 42. The width of the clearance between the

legs

352 and 354 is necessarily equal to the bottom clearance between the

longitudinal grooves

40 and 42.

The two

legs

352 and 354 of the key 350 are formed with

engagement elements

356 and 358 at the front edges thereof. The

engagement elements

356 and 358 are shaped like so-called projections extending outwardly, having specific configurations depending upon the configurations of mating engagement members, as later described. As will become clear from the subsequent description, the engagement elements 356 (hereinafter referred to as the first engagement element) performs the unlocking preparation action, while the other 358 (hereinafter referred to as the second engagement element) performs the unlocking action.

The insertion of the key 350 into the rotary shaft 38 is effected so that with the latter taking a position shown in FIG. 4 the leg 352 on the side of the first engagement element 356 may be fitted in the longitudinal groove 40. Therefore, the leg 354 on the side of the second engagement element 358 is necessarily inserted into the longitudinal groove 42.

After the key 350 is mounted in the rotary shaft 38 in the manner described above, as it is turned clockwise, the first engagement element 356 first engages its mating engagement member 44 (FIG. 5b). The mating engagement member 44, as shown exploded in FIG. 8, consists of several substantially semi-circular flat engagement elements 46-64 placed one upon another, having central openings 66-84 narrow slots 86-104 and arcuate elongated or circular openings 106-124 located intermediate of the radius. The

engagement elements

48, 50, 54, 56, 60, 62 and 64, except 46, 52 and 58, have linear springs 126-138 fixed at one of their respective ends to one of the respective end surfaces 140-152, thereof as by welding. Each of the narrow slots 86-104 of the engagement elements 46-64 is different in the position where it is formed from the others, whereby the order of superposition of the elements 46-64 and the shape of the first engagement element 356 of the key are determined. In the assembled condition, a central shaft 154 whose cross-sectional shape is a partially cut-away circle is inserted into the central openings 66-84 in the elements 46-64, while a single small shaft 156 is inserted into arcuate

elongated openings

108, 110, 114, 116, 120, 122 and 124 or

circular openings

106, 112 and 118. The central shaft 154 is rotatably supported between the front and

rear plates

22 and 24 of the lock case 20, and its relation to the elements 46-64 is such that only the element 64 having the central opening 84 of the same cross-sectional shape is prevented from its rotation relative to the shaft 154 while the other elements 46-62 having central openings 66-82 ofcircular shape are loosely fitted over the shaft 154. The small shaft 156 inserted in the

elongated openings

108, 110, 114, 116, 120, 122 and 124 or

circular openings

106, 112 and 118 is vertically mounted between the front and

rear plates

22 and 24 and fixed therein, and has a diameter just large enough to be loosely fitted in the

circular openings

106, 112 and 118 in the elements 46, 52 and 58. The arcuate

elongated openings

108, 110, 114, 116, 120, 122 and 124 in the

elements

48, 50, 54, 56, 60, 62 and 64 each have a width corresponding to the diameter of the small shaft 156, and these elements are capable of being turned relative to the small shaft 156 through an angle corresponding to the length of the

elongated openings

108, 110, 114, 116 120, 122 and 124.

The mating engagement member 44 associated with the first engagement element 356 is constructed in the manner described above, and the initial assembling thereof is effected sothat the superposition surfaces of the elements 46-64 completely overlap each other. At this time, the free ends of the springs 126-138 are engaged with a pin 158 fixed to the rear plate 24, whereby the

elements

48, 50, 54, 56 60, 62 and 64 are urged in a clockwise direction until a position with the maxium degree of rotation is attained, that is, the small shaft 156 is positioned at one end of the

elongated openings

108, 110, 114, 116, 120, 122 and 124 to prevent the further clockwise rotation of the elements. Further, with the superposition surfaces of the elements 46-64 completely overlapping each other, since the slots 86-104 are formed at mutually different rotational phase positions, their relative phases are different from each other at the time of the initial setting, as is clear from FIG. 7b.

On the other hand, the first engagement element 356 of the key 350 is shaped to have seven projections 360-372 of different lengths having a width corresponding to the thickness of said elements 46-64. When the key 350 is turned clockwise in FIGS. 5a and 5b, it engages the other end surfaces 160-172 of the

engagement elements

48, 50, 54, 56, 60 and 64 and turns the latter counterclockwise through different angles corresponding to the lengths of the projections 360-372 against the forces of the springs 126-138. This is because at the time of turning of the key 350, the lengths of time of engagement with the end surfaces of the elements are different according to the lengths of the projections. In addition, in this case, the insertion of the small shaft 154 in the

circular openings

106, 112 and 118 prevents the engagement elements 46, 52 and 58 from being turned. Thus, these elements, unlike the

elments

48, 50, 54, 56 and 60-64 having elongated

openings

108, 110, 114, 116 and -124 are stationary without being allowed to perform rotation. Therefore, the first engagement element 356 of the key 350 is not formed with projections at the corresponding positions thereon but it has recesses 374-378 so thatit will not engage them. However, this is only an example, and it is, of course, possible to form these elements, like the other elements, with elongated openings to allow rotation, and form the first engagement element 356 with corresponding projections at the regions 374-378. In reverse, additional elements having circular openings as in the elements 46, 52 and 58 may be provided.

Thus, in the present invention, some amounts of rotational displacement corresponding to the lengths of the projections 360-372 (it has been stated above that the recesses 374-378 can be comprehended in the category of the projection) are imparted to the

engagement elements

48, 50, 54, 56 and 60-64, whereby the slots 86-104, which were initially in different rotational phases, take the same phase, that is, they become aligned with each other. With this condition established, a hook 176 at the front end of an L-shaped leaf spring 174 falls in the aligned slots 86-104 to hold all the elements in this condition (FIG. 50). The leaf spring 174 is pressed against a bifurcated lever 178 energized clockwise by a leaf spring 182 to have its upper inner side engaged with the rotary shaft 38. Normally, as shown in FIG. 5a, the leaf spring 174 is receiving a pressure on the side of the hook 176 from one end 180 of the lever 178 but when the key 350 is turned to impart rotational displacement to the

elements

48, 50, 56 and 60-64, the shoulder 380 of the second engagement elment 358 engages the other inner arcuate side of the bifurcated lever 178 to turn the latter counterclockwise around the axis of the pivot 184. As a result, the restraining force on the hook side of the leaf spring 174 disappears, so that, with the slots aligned, the hook 176 at the front end of the leaf spring 174 is instantly fitted in the slots by its elasticity.

Fixed on the central shaft 154 of the engagement member 44 in connection with the first engagement element 356 is a sector gear wheel shown at 186 placed on the element layer. The sector gear wheel 186 is formed with an axial opening 187 of the same crosssectional shape as that of the central shaft 154, so that when said wheel is fitted over the central shaft 154, the rotation thereof is restrained integrally with the central shaft 154. As described above, of the ten elements, only the element 64 is restrained so that it will rotate integrally with the central shaft 154. However, in the above-mentioned rotation, when the projections 360-372 of the key 350 on the first engagement element 356 engage the

elements

48, 50, 54, 56, and 60-64 to rotate the latter, the rotation of the element 64 causes the rotation of the central shaft 154 and sector gear wheel 186.

The mating engagement member 188 engageable with the other engagement element formed on the key 350, that is, the second engagement element 358 consists of three

parts

190, 192 and 194 shown in FIG. 9 fitted over a single central shaft 196. The annular part 192 and the partial gear wheel 194 are made integral with each other by fitting the latter in a notch 198 formed in the upper end of the former, said partial gear wheel 194 being engaged with the sector gear wheel 186. The annular part 192 is formed with a circumferentially extending elongated window 200 at a substantially middle level position, and at the level of said window 200, there is formed an engagement projection 202 engageable with the projection 382 of the second engagement projection 358 and radially extending from the central shaft 196. The size of the window 200 is such that when it faces toward the rotary shaft 38, the projection 382 on the second engagement element 358 of the key 350 is allowed to be turned through the window without hindrance, said window being located in the path of rotation of the projection 282. Though not shown clearly, the window 200 normally is deviated from the rotary shaft 38 toward the side. Therefore, in this condition even if the key 350 is turned clockwise, the projection 382 on the second engagement element 358 hits the peripheral surface of said annular part 192, so that it cannot engage the engagement projection 202 located inside. The side of the partial gear wheel 194 opposite to the side formed with the teeth is formed with a notch 204, in which, as shown in FIG. 5a, is normally fitted the hook 212 of a lever 210 surged to turn clockwise around the axis of a pivot 208 by a leaf spring 206, thereby preventing the rotation of the annular part 192 integral with the partial gear wheel 194. Further a projection 214 formed on the other end side of said bifurcated lever 178 engages said lever 210 at substantially the middle of the lateral portion thereof. Thus, as the key 350 is turned clockwise, the bifurcated lever 178 is turned counterclockwise by the shoulder 380 of the second engagement element 358. Along with this rotational movement, the lever 210 is urged to turn clockwise around the axis of the pivot 208, so that the hook 212 is disengaged from the notch 204. As a result, the partial gear wheel 194 and annular part 192 are made free to rotate and rotated by the sector gear wheel 186 (FIG. 5b).

As is clear from the above, when the key 350 is turned clockwise from the conition shown in FIG. 5a through about A of one complete revolution, the hook 176 of the leaf spring 174 is fitted in the slits with the action described above and the sector gear wheel is rotated, whereby the annular part 192 having the partial gear wheel 194 meshing therewith is rotated to cause the window 200 formed therein to be directed toward the rotary shaft 38 (FIG. 5d). The actions described so far correspond to the so-called unlocking preparation action, and upon completion of these actions, the second engagement element 358 of the key 350, without hitting the annular part 192, is rotated through the window 200 capable of engaging the mating engagement member 202 disposed therein.

In the above-mentioned unlocking preparation action, when the first engagement element 356 completes engagement with the

engagement elements

48, 50, 54, 56, 58 and 60-64 and is disengaged therefrom (FIG. 5d), the

elements

48, 50, 54, 56, 58 and 60-64 tend to return to the original position under the action of the springs 126-138. However, such reverse rotation is prevented since the hook 176 is fitted in the slots 86-104 in the engagement elements 46-64. In this way, the sector gear wheel 97 and the annular part 101 having the partial gear wheel 194 are firmly held in the position shown in FIG. 5d, thereby allowing the projection 382 on the second engagement element 358 to enter the window 200 without hindrance.

The central shaft 196 of the mating engagement member 188 associated with the second engagement element has a substantially flat part shown at 190 fixed to the lower end thereof, as described above. As shown in FIG. 5d, the relieved end surface 216 of said part has engaged therewith the hook 220 ofa pusher 218 which, when seen in a front view, is substantially channelshaped. Further, a pin 226 having the function of supporting the annular part 190 is engaged with the end surface 224 of a notch 222. In addition, in the annular part 190, a relieved end surface 228 is provided for securing a passage for a projection on the lower portion of the second engagement element 358 when the key 350 is inserted and turned.

Thus, when the key 350 is turned clockwise from the condition shown in FIG. 5d and the projection 382 on the second engagement element 358 engages the projection 202 on the central shaft 196 to turn the latter counterclockwise, the part 190 receives a torque in the same direction, so that the relieved end surface 216 acts to push the pusher 218 to the left as seen in FIG. 5e. This leftward push is imparted to a central projection 230 on the locking piece 32 which is in contact with the left-hand side of the hook 220, whereby the locking piece 32 is slid to the left to expedite disengagement of the right-hand side projection 34 and one end of the U-shaped portion of the lock piece 28 from each other.

The related construction of the pusher 218 and locking piece 32 is shown in detail in FIGS. d, 5e and 5f and FIG. 6. The pusher 218, which, when seen in a front view, is channel shaped as previously described, is held slidable right and left by a holder 232 fixed to' the locking piece 32 and has a right-hand side hook 234, against which a leaf spring 236 is urged from the left, whereby said hook 234 is constantly urged toward the right. As a result of such rightward urging on the pusher 218, the part 190 engaged therewith at the end surface 216 is necessarily constantly urged clockwise.

On the other hand, the locking piece 32 is a flat part which, in addition to the previously described righthand side projection 34 and central projection 230, is provided with another left-hand side projection 238 and is held slidable right and left with respect to the rear plate 24 in such a condition that pins 244 and 246 fixed to the rear 3 are loosely inserted in longitudinally extending

elongated openings

240 and 242 formed in the ends of the locking piece 32. The locking piece 32 is constantly urged to the right by a leaf spring 248 which is pressing the left-hand side projection 238 on the locking piece 32 is a detent 250 which engages the front end of said projection 238 in this locked condition. The detent 250 which extends downwardly at right angles with the locking piece 32. Like the locking piece 32, it is held slidable with respect to the rear plate 24 with pins 256 and 258 loosely fitted in

elongated openings

252 and 254. The detent is formed with a hook 260 on the lower right-hand side portion against which a leaf spring 262 is urged from below, whereby the detent is constantly upward urged. The pusher 218 and locking piece 32 are arranged in the related construction described above. In such arrangement, the clockwise turning of the key 350 imparts of leftward push to the locking piece 32 through the relieved end surface 216 of the part 190, the hook 220 of the pusher 218 and the central projection 230 on the locking piece 32, whereupon the locking piece 32 is moved to the left guided by the

pins

244 and 246. Along with this movement, the engagement between the right-hand side projection 34 and one end of the U-shaped portion of the lock piece 28 and engagement between the left-hand side projection 238 and the detent 250 are gradually cancelled. Upon complete cancellation of these engagements, the detent 250 is upwardly moved by the elasticity of the leaf spring 262 until it engages the right-hand side of the left-hand side projection 238 on the locking piece 32, so that the locking piece 32 is held in this condition and the unlocking operation is thus completed. The condition in which the unlocking operation is completed is shown in FIGS. 5f and 6. While the key 350 is being turned clockwise from the condition shown in FIG. 5d to the condition shown in FIG. 5f, along with the above-mentioned leftward movement of the locking piece 32 and the holding of said locking piece 32 by the detent 250, return movement of the constituent members to their original positions (FIGS. 4 and 5a) is simultaneously effected. That is, when the key 350 is turned clockwise a little further from FIG. 5e, the engagement between the projection 382 on the second engagement element 358 and the projection 202 on the central shaft-196 and engagement between the shoulder 380 of the key 350 and the upper inner arcuate side of the bifurcated lever 178 are both cancelled. Upon cancellation of the former engagement, since the action by which the end surface 216 presses the pusher 218 disappears, the pusher 218 is slid to the right by the elasticity ofthe leaf spring 236. As a result, the part 190 is turned clockwise until it returns to its original position, that is, the position where the end surface 224 of the notch 222 engages the pin 226. Upon cancellation of the latter engagement. since the force turning the bifurcated lever 178 counterclockwise disappears, said lever l78 is subjected to the elasticity of the leaf spring 182 and the upper inner side which has been engaged with the projection 382 on the key 350 up to now is turned clockwise until it abuts against the rotary shaft 38. As a result, there occur successively the withdrawal of the hook 176 of the leaf spring 174 from the slits 86-104, return movement of the

engagement elements

48, 50, 54, 56 and -64 to their original positions by the action of the springs 126-138, return movement of the central shaft 154 and sector gear wheel 186 due to the rotational return movement of the element 64, return movement of the partial gear wheel 194 and annular part 192, and insertion of the hook 212 of the lever 210 into the notch 204 of the partial gear wheel 194. Thus, all the mechanisms except those directly related to the locking piece 32 return to the same condition as the initial locked condition.

Now, in reverse, when it is desired to lock the thus unlocked lock, in FIG. 6 this is achieved by inserting the key 350 into the rotary shaft 38 in the same condition as in the unlocking operation and turning the key counterclockwise together with the rotary shaft 38. When such turning operation of the key is effected, the projection 384 on the lower portions of the second engagement element 358 engages the hook 260 of the detent 250. As a result, the detent 250 is downwardly pushed while being guided by the pins 256 and 258. When the detent is downwardly moved in this manner over a fixed distance, the engagement between the de tent 250 and the left-hand side projection 238 on the locking piece 32 is cancelled, so that the locking piece 32 is moved to the right under the action of the leaf spring 248 to being about engagement between the front end of the right-hand side projection 34 on the locking piece 32 and one end of the U-shaped portion of the lock piece 28 (at this time, the left-hand side projection 238 on the locking piece 32 and the upper end surface of the detent 250 engage each other), whereby locking is completed (see FIGS. 4 and 5e).

The foregoing description refers to the details of the construction for effecting ordinary locking and unlocking by using a key 350 for the lock according to the present invention. However, this lock is provided with an additional mechanism which is associated with the mechanisms described so far to effect locking and unlocking from within a room without using a key. This mechanism comprises

pins

264 and 266 fixed upright on the left-hand side portion of the locking piece 32 and the detent 250, respectively, and a rotary shaft 272 rotatably supported at the lower end by the rear plate 24 and at the intermediate portion by the front plate 22 and having

parts

268 and 270 inwardly engageable with said

pins

264 and 266, respectively. The rotary shaft 272 is adapted to be turned counterclockwise by the upward movement of the detent 250 upon the abovedescribed unlocking operation on the one hand and on the other hand clockwise by the rightward movement of the locking piece 32 upon the locking operation. Thus, in the locked condition shown in FIG. 4, if the rotary shaft 272 is turned counterclockwise, the locking piece 32 receives a leftward push at the part 268 from the pin 264 and is the thereby positively moved to the left over a fixed distance, whereupon the detent 250 is upwardly moved to engage the left-hand side thereof In this manner, the same unlocked condition as described above is established. Further, in the unlocked condition shown in FIG. 6, if the rotary shaft 272 is turned clockwise in reverse, the engagement between the part 270 and the pin 266 causes the downward movement of the detent 250, with the result that the engagement between the detent 250 and the left-hand side projection 238 on the locking piece 32 in the unlocked condition is cancelled, allowing the locking piece 32 to move to the right, whereby locked condition is established.

While an embodiment of the lock of the present invention has been described so far centered around its actions, various partial modifications may be made of the lock from the standpoint of prevention of unauthorized unlocking by false keys. One such modification will now be described with reference to FIGS. 11a and 11b. In this modification, a leaf spring 174 adapted to be fitted in the slots in the engagement elements to hold them in the unlocking preparation condition is held in a spring retainer 300 associated with the bifurcated lever 178, the arrangement being such that only when said hold is cancelled the leaf spring 174 is allowed to be fitted in the slots. As shown in FIG. 11a, the spring retainer 300 is a flat

piece having hooks

302 and 304 at the ends thereof and notched from the substantially middle to the left-hand side hook 304. The spring retainer is supported slidable right and left in that pins 306 and 308 preferably fixed to the rear plate 24 are fitted in an elongated opening 310 longitudinally formed in the spring retainer. Further, is is constantly urged to the left by a leaf spring 312 which is contacted with the right-hand side hook 302 from the right. The spring retainer 300 is centrally formed with a recess 316 in which the front end of the leaf spring 174 is fitted. The left-hand side hook 304 is engaged with the front end 180 of the bifurcated lever 178 which is also engaged with the leaf spring 174. Thus, with such arrangement, the clockwise turning of the key 350 in the condition shown in FIG. 110 results in the counterclockwise rotation of the bifurcated lever 178 as the latter engages the shoulder 380 of the second engagement element 358, whereby the front end 180 of the lever 178 is moved away from the side of the leaf spring 174. Thus, the leaf spring 174 is now held by the spring retainer 300 alone. The spring retainer 300 is urged by the front end 180 ofthe lever 178 to move to the right. As a result, the length of the front end 314 of the leaf spring 174 which is engaged with the recess 316 of the spring retainer 300 becomes gradually shorter. As the rotation of the key 350 further proceeds to a certain position, the front end 314 of the leaf spring 174 becomes completely separated from the recess 316 in the spring retainer 300, whereupon it enters the slots in the engagement elements which have been aligned, so that the elements are now held in the unlocking preparation condition.

In this modification, the detent 250, which, at the time of unlocking, prevents the rightward movement of the locking piece 32 to hold the lock in its unlocked condition has the same function of direct locking as the lock piece 28. That is, as shown in FIGS. 11a and 11b, the length of the detent 250 at the time of locking, the right-hand end projects through the lateral plate 26 of the lock case 20 substantially the same distance as in the case of the lock piece 28 to effect locking and that at the time of unlocking, it is completely received in the lock case 20 to cancel the locked condition. In addition, in order for the detent 250 to fully develop its locking function, it is, of course, desirable that it has a greater width and thickness than in the embodiment described above so as to have a sufficient strength.

What I claim is:

1. A lock comprising a single key having first and second engagement elements, a rotary shaft having longitudinal grooves adapted to receive both engagement elements of said key, a first mating engagement member associated with said first engagement element arranged around said rotary shaft so that it is engaged by said first engagement element upon the first rotation of said single key together with said rotary shaft through a given angle, a second mating engagement member associated with said second engagement element arranged around said rotary shaft so that it is engaged by said second engagement element upon the rotation of said key together with said rotary shaft through a fixed angle subsequent to said first rotation of said key, engagement prevention-cancelling means operatively connected to said two mating engagement members in such a manner that before said first engagement element engages its mating engagement member, said second engagement element is rendered unable to engage its mating engagement member, and that after said first engagement element engages its mating engagement member, said second engagement element is rendered able to engage its mating engagement member, and unlocking operative means operatively connected to the mating engagement member associated with said second engagement element in such a manner that it is actuated upon engagement of said second engagement element with its mating engagement member.

2. A lock according to claim 1, wherein said mating engagement member associated with said first engagement element consists of several flat engagement ele ments whose shape and overlapping relations are selected to take mutually different relative phases with respect to a particular phase, and which are loosely fitted over a single central shaft in overlapping relation.

3. A lock according to claim 2, wherein said engagement prevention-cancelling means is arranged so that only when said first engagement element engages its mating engagement member to cause the mutual relation of said elements to take said particular phase, it is actuated to bring the mating engagement member associated with second engagement element into condition where said mating engagement member is engageable with the second engagement member.

4. A lock according to claim 2 wherein said first engagement element of the key is formed with ridges and recesses depending upon the shape and overlapping relation of said elements to impart said particular phase.

5. A lock according to claim 1, wherein said unlocking operative means is adapted to be actuable also by a manual unlocking operative shaft installed independently of said other constituent members except said unlocking operative means.

6. A lock according to claim I, wherein a member constituting the unlocking operative means has the function of a lock piece.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 869 888 DATED March 11, 1975 INVENTOR(S) Kenzo Yoshizawa It is certified that error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:

The following should be inserted as line [73]" on the Title Page:

-- [73] Assignee: YOSHIZAWA KOGYO CO. LTD., Kyoto, Japan Signed and Scaled this fourth Day Of November19 75 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Offiter Commissioner oj'Parenls and Trademarks

Claims

2. A lock according to claim 1, wherein said mating engagement member associated with said first engagement element consists of several flat engagement elements whose shape and overlapping relations are selected to take mutually different relative phases with respect to a particular phase, and which are loosely fitted over a single central shaft in overlapping relation.