GB2141480A

GB2141480A - Cylinder lock

Info

Publication number: GB2141480A
Application number: GB08410687A
Authority: GB
Inventors: Hwang Shih-Ming
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-17
Filing date: 1984-04-26
Publication date: 1984-12-19
Also published as: GB8410687D0; GB2141480B

Abstract

In an axial-pin cylinder lock, to prevent picking, the lower pin tumblers 1 sliding in lower pin holes are provided at each end with a flange 11, the flanges being a sliding fit in the pin holes except at the upper end of the pin hole where a recess 411 permits sideways movement of the flange. The upper end of each lower pin tumbler 1 extends beyond the upper flange 11 and, when the upper flange is located in the recess, projects into the corresponding upper pin hole to prevent turning of the lock. <IMAGE>

Description

SPECIFICATION Improved tubular locks This invention relates to improved tubular locks which are difficult to pick and so provide better security.

Most tubular locks sold on the market at present are easy to pick. Fig. 10 and Fig. 11 show a fragmentary perspective view of a known tubular lock and a crosssectional view of the known lock, respectively. As shown, tne known tubular lock comprises a housing (1) in wnich a plurality of upper pin-tumblers (C), a bolt (B), an upper plug (D), a plurality of springs (G) and a lower plug (E) are mounted.

Each upper pin-tumbler (C) has a different length from the others; the same is true of the lower pin-tumblers (H). The upper pin-tumblers (C) are inserted into upper pin holes of the upper plug (D) which is fixed to the bolt.

The lower pin-tumblers (H) together with the springs (G) are inserted into lower pin holes (F) of the lower plug (E). The number of the upper pin-tumblers (C) is equal to the number of lower pin-tumblers (H) and is also equal to the number of the springs (G). The bolt (B) extends through the upper plug (A), the lower plug (E), a blocking plate (K) and is screwed into a nut (T). Each lower pin-tumbler (H) is aligned with each upper pin-tumbler (H) and extends from the lower plug (E) into each upper pin hole (D). The combination of the upper plug (A), the bolt (B) and the lower plug (E) are installed into the housing (I) and fixed by means of inserting a pin (Y) into the lower plug (E). The pin-tumblers are spring-loaded so that they are always in the locking position except when the proper key is inserted.

As shown in Fig. 1 2 a correct key (J) is inserted into the known lock to lower the upper pin-tumblers (C) which in turn press down the lower pin-tumblers (H) to the correct height so as to enable the upper plug (A) to turn, thus allowing the upper plug (A) to revolve and release the bolt (B).

Fig. 14, Fig. 1 5 and Fig. 16 illustrate the use of the pick tool shown in Fig. 1 7 to pick the known lock. First, insert each pin (R) of the pick tool shown in Fig. 1 7 into each upper pin hole (D) to lower the upper pintumblers (C), which in turn push the lower pintumblers (H) to the bottom of the lower pin holes (D). Then, turn the pick tool clockwise and counterclockwise alternately, thereby slightly rotating the upper plug (A) clockwise and counterclockwise alternately. The reason why the upper plug (A) can slightly be rotated clockwise and counterclockwise is that the diameter of the upper pin-tumbler (C) must be smaller than that of the upper pin hole (D).

Since the lower pin-tumblers (H) are spring loaded, they will go upwards until their tops are in contact with the bottom surface of the upper plug (A) while the upper plug (A) is slightly rotated clockwise and counterclockwise, i.e., the lower pintumblers (H) are lifted to the correct height. Thus the upper plug (A) is allowed to revolve and the bolt (B) is released.

Fig. 1 8 illustrates the use of the pick tool shown in Fig. 9 to pick the known lock First, slightly insert the pick tool shown in Fig. 9 into the upper plug (A), and at the same time turn it clockwise and counterclockwise alternately. Thus the upper plug (A) is rotated clockwise and counterclockwise alternately. In consequence the lower pin-tumblers (I) will go downward until their tops are in contact with the bottom surface of the upper glug (A) while the upper plug (A) is being slightly rotated clockwise and counterclockwise, i. e., the lower pintumblers (H) are lowered to the correct height. Thus the upper plug (A) is allowed to revolve and the bolt (B) is released.

The present invention provides an improved tubular lock which is less easy to pick and offers a higher degree of security.

According to the present invention a tubular lock comprises: a housing; a bolt; an upper plug having a plurality of upper pin holes, each containing an upper pin tumbler, and being fixed on said bolt; a lower plug having a plurality of lower pin holes each provided with a recess at that end of the pin hole adjacent the upper plug; a plurality of lower pin-tumblers, one located in each of the lower pin holes, each lower pin tumbler being provided with a flange near each end, the flanges being a sliding fit in said lower pin holes; and a plurality of springs located in said lower pin holes and serving to urge the lower pintumblers to the locking positions where they project into the upper pin holes.

The lower pin-tumblers are of smaller diameter than the upper and lower pin holes of the lock and the flanges, which are of greater diameter than the lower pin-tumblers, are a sliding fit in the upper and lower pin holes.

There is such a flange near each end of each lower pin-tumbler, the flange at the upper end being located near, but not at, the upper end of the lower pin-tumbler so that the upper end of the lower pin-tumbler projects upwardly beyond the flange.

The recess in the lower pin holes may take the form of a counter bore in the upper end of the lower pin hole, i.e., the end adjacent the upper plug, the counter bore being of greater diameter than the pin hole so that when the flange near the upper end of a lower pintumbler is within the recess, the upper end of the lower pin-tumbler may be displaced sideways so that the flange may be supported on the bottom of the recess. The depth of the recess and the length of the upper end of the lower pintumbler extending beyond the flange is such that when the upper end of the lower pin-tumbler is displaced sideways in this manner, the upper end of the lower pintumbler still projects into the upper pin hole and prevents the lock being turned.

The construction and operation of one embodiment of the invention is now explained, by way of example, with reference tothe accompanying drawings in which: Fig. 1 is a fragmentary perspective view; Fig. 2 is a cross-sectional view; Fig. 3 is an enlarged perspective view, partly in section, of the lower plug shown in Fig. 1; Fig. 4 is a cross-sectional view showing that the proper key has been inserted into the tubular lock according to the preferred embodiment of the present invention; Fig. 5 is an end-view of Fig. 4; Fig. 6 shows the sizes of the lower pintumbler and the lower pin hole; Fig. 7 is a cross-sectional view showing why it is impossible to use the pick tool shown in Fig. 1 7 to pick the lock constructed according to the present invention; Fig. 8 is a cross-sectional view showing the failure of another picking method;; Fig. 9 is a perspective view of a pick tool; Fig. 10 is a fragmentary perspective view of a known tubular lock; Fig. 11 is a cross-sectional view of the known tubular lock shown in Fig. 10; Fig. 1 2 is a cross-sectional view showing that the correct key has been inserted into the known tubular lock; Fig. 13 is an end view of Fig. 12; Fig. 14, Fig. 1 5 and Fig. 16 show how to use the pick tool shown in Fig. 1 7 to pick the known lock; Fig. 1 7 is a fragmentary perspective view of another pick tool; Fig. 18 shows how to use the pick tool shown in Fig.9 to pick the known lock.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENT: Referring to Fig. 1 and Fig.2 the lock comprises a housing (200) in which a plurality of upper pintumblers (3), a bolt (20), an upper plug (2), a plurality of lower pin-tumblers (1), a plurality of springs (6), and a lower plug (4) are mounted. Each upper pin-tumbler (3) has a different length from the others, and the same is true of the lower pin-tumblers. The upper pintumblers (3) are inserted into upper pin holes (21) of the upper plug (2). The upper plug (2) is fixed to the bolt (20). Each lower pin-tumbler (1) is provided with two flanges (11). The lower pin-tumbers (1) together with the springs (6) are inserted into the lower pin holes (41) of the lower plug (4).

The number of the upper pin-tumblers (3) is equal to the number of the lower pin-tumblers (1) and is also equal to the number of the springs (6). The bolt (20) extends through the upper plug (2), the lower plug (4), a blocking plate (50) and a locking plate (60), and is screwed into a nut (70). Each lower pintumbler (1) is aligned with each upper pintumbler (3) and extends from the lower plug (4) into each upper pin hole (21). The combination of the upper plug (2), the bolt (20) and the lower plug (4) are installed into the housing (200) and fixed by means of inserting a pin (80) into the lower plug (4). The pintumblers are spring-loaded so that they are always in the locking position except when the proper key is inserted.

Referring to Fig. 3 at the upper part of each pin hole (41) of the lower plug (4) is a recess (411). The depth of each recess (411) is different from the others.

Referring to Fig. 4 a proper key (5) is inserted into the lock according to the preferred embodiment of the present invention to lower the upper pin-tumblers (3) which in turn press down the lower pin-tumblers (1) to the correct height so as to allow the upper plug (2) to revolve and release the bolt (20).

Referring to Fig. 6 if the height of the flange (11) be A, then the depth of the recess (411) is suitably 1.1A and the length of the upper end (12) is 2A; if the depth of the lower pin hole (41) be B, then the diameter of the recess (411) is suitably 1.2B.

Fig 7 shows why it is impossible to use the pick tool shown in Fig. 1 7 to pick the lock according to the present invention. Each pin (R) of the pick tool shown in Fig. 1 7 is inserted into each upper pin hole (21) to lower the upper pin-tumblers (3) which in turn push the lower pin-tumblers (51) to the bottom of the lower pin holes (41). Then, turn the pick tool clockwise and counterclockwise alternately, thereby slightly rotating the upper plug (2) clockwise and counterclockwise alternately. The reason why the upper plug (2) can slightly be rotated clockwise and counterclockwise is that the diameter of the upper pin-tumbler (3) must be smaller than that of the upper pin hole (21). Since the lower pintumblers (4) are spring-loaded, they will go upwards until the flanges (11) are in contact with the bottom surface (22) of the upper plug (2) while the upper plug (2) is being slightly rotated clockwise and counterclockwise. As a result, the upper ends (12) of the lower pin-tumblers (1) will go into the pin holes (21) of the upper plug (2). In other words, the rotation of the upper plug (2) is prevented by the lower pin-tumblers (1), i.e., it is impossible to pick the lock according to the present invention.

Fig. 8 shows why it is impossible to use another pick tool shown in Fig. 9 to pick the lock according to the present invention. The pick tool shown in Fig. 9 is first slightly inserted into the upper plug (2), and at the same time is turned clockwise and counterclockwise alternately. Thus the upper plug (2) is slightly rotated clockwise and counterclockwise alternately. In consequence, the lower pin-tumblers (1) will go downward until the flange (11) of the lower pin-tumbler is in contact with the recess (411). In other words, the rotation of the upper plug (2) is prevented by the upper ends (12) of the lower pintumblers (1), i.e. it is impossible to pick the lock according to the present invention.Nevertheless, once the flange (11) at the upper part of the lower pintumbler (1) goes into the lower pin hole (41), the upper pin-tumblers (3) will go into the recess (411) too, so that the rotation of the upper plug (2) is prevented by the upper pin-tumblers.

In order to increase the safety of the present invention, the height of each flange (11) may be different from the others.and the same is true of the recesses.

In brief, in the tubular lock of this invention the lower pin tumblers sliding in lower pin holes are provided at each end with a flange, the flanges being a sliding fit in the pin holes except at the upper end of the pin hole where a recess permits sideways movement of the flange. The upper end of each lower pin tumbler extends beyond the upper flange and, when the upper flange is located in the recess, projects into the corresponding upper pin hole to prevent turning of the lock.

Claims

1. A tubular lock comprising: a housing; a bolt; an upper plug having a plurality of upper pin holes, each containing an upper pin tumbler, and being fixed on said bolt; a lower plug having a plurality of lower pin holes each provided with a recess at that end of the pin hole adjacent the upper plug; a plurality of lower pin-tumblers, one located in each of the lower pin holes, each lower pin tumbler being provided with a flange near each end, the flanges being a sliding fit in said lower pin holes; and a plurality of springs located in said lower pin holes and serving to urge the lower pintumblers to the locking positions where they project into the upper pin holes.

2. A lock as claimed in claim 1 in which the recess in the lower pin holes is a counter bore.

3. A lock as claimed in claim 2 in which the depth of the counter bore and the length of the upper end of the lower pin-tumbler extending beyond the flange is such that when the flange is displaced sideways in the counter bore, the upper end of the lower pintumbler projects into the upper pin hole.

4. A lock as claimed in claim 1, 2 or 3 in which each upper pin-tumbler and each lower pin-tumbler has a different length from the other upper and lower pin-tumblers respectively.

5. A lock as claimed in any preceding claim in which the height of each flange and the depth of each recess is different from the other heights and depths respectively.

6. A lock as claimed in claim 1 and substantially as described with reference to Figs.

1 to 6 of the accompanying drawings.