The present patent application claims priority from and the benefit of Hong Kong Patent Application No. 06113261.9, filed Dec. 1, 2006, and entitled PIN TUMBLER LOCK, which prior application is hereby incorporated herein by reference.
The present invention relates to a pin tumbler lock.
A pin tumbler lock is a type of lock commonly used, for example, in doors of houses. A pin tumbler lock includes a housing shell and a plug forming an interface surface. The shell and the plug each contain a number of radial bores corresponding with those in each other. Each bore in the shell contains a first pin and each bore in the plug contains a second pin. In the locked position, a biasing device in each of the bore pushes the first pin against the second pin, such that a pin in each bore is positioned across the interface surface between the plug and the shell to bolt the lock. When the correct key is inserted into the keyhole on the plug, the second pins inside the bores of the plug will be pushed outwardly against the corresponding first pins in the shell, such that the contact surfaces between all the first and the corresponding second pins align with the interface surface between the plug and the shell. In such position, the pins do not bolt the lock and the key can rotate the plug to open the lock. If the key does not match with the plug, some or all the first or the second pins will be positioned cross the interface surface between the plug and the shell to bolt the lock. Accordingly, the key cannot then turn the plug to open the lock.
Pin tumbler locks are popularly used, and there emerges various methods of opening a pin tumbler lock without a mating key, for example, by using a bump key. This method requires the use of a special key, on which all the depressions on the shank of the key are grinded to a certain depth, such that when the key is inserted into the keyhole, all the second pins remain in the bore of the plug. At this position, all the second pins are in contact with the corresponding first pins. When the bump key is hit by a tool on the key head, the momentum is transmitted from the second pin to the first pin in contact, causing a momentary separation between all the first and the second pins. If all the first and the second pins are separated at the same time, and all the open spaces between the first and the second pins so formed are aligned with the interface surface between the shell and the plug, the key can turn the plug to open the lock.
There is no solution yet to prevent lock picking using bump key. This invention provides a pin tumbler lock that prohibits picking by bump key.
It is an objective of the present invention to provide an improved pin tumbler lock that prohibits picking by using bump keys.
The pin tumbler lock of the present invention, operating between a locked position and a released position, comprises a first lock member and a second lock member. The first lock member has at least one first bore with a biasing device and a first pin deposing in the first bore. The second lock member engages with the first lock member, and forms an interface surface with the first lock member. The second lock member has at least one second bore with a second pin disposed in the second bore.
In the locked position, the first bore is aligned with the corresponding second bore, and the first pin forms a contact surface with the second pin. The first pin is forced into the second bore by the biasing device and deposes across the interface surface to lock the first and second lock members. In the released position, the first pin is forced by the second pin to a position where the contact surface is aligned with the interface surface.
At least one of the external and internal pins is magnetized, and the other corresponding pin is magnetic permeable.
When the pins are mobilized by a bump key, the magnetized pins remain attracted to the corresponding magnetic permeable pin such that no open space between the first and the second pins is formed at the interface surface between the lock members to release the lock. The lock therefore prevents against lock picking by using bump keys.
The above and other aspects, features, and advantages of the present invention will become more apparent upon consideration of the following detailed description of preferred embodiments, taken in conjunction with the accompanying drawing figures, wherein:
a and 2b are the perspective internal views illustrating the locked position and the released position of the pin tumbler lock of
a and 3b are the perspective internal views illustrating how the pin tumbler lock of
a and 4b are the perspective internal views of the pin tumbler lock according to another embodiment of the present invention.
As shown in
The second lock member may be a plug 40. In this embodiment, the plug 40 is cylindrical and is surrounded by shell 20. An interface surface 60 is formed between the shell 20 and the plug 40. There is a keyhole 42 on the plug 40 for the insertion of a key 10. The keyhole 42 is connected with at least one radial second bore 44 on the plug 40 at one end 44a of the second bore 44. The other end 44b of the second bore 44 is an opening 46, which corresponds to the opening 26 of the first bore 24. Each of the second bores 44 contains a second pin 50 of different sizes. In the locked position, the biasing device 28 releases and pushes the first pin 30 against the second pin 50, such that the first pin 30 is bolted across the interface surface 60 to lock the shell 20 and the plug 40.
As shown in
In an embodiment of the invention, at least one of the first pin 30 and the second pin 50 is magnetized, while the other pin is magnetic permeable and is attracted to the magnetized pin by containing, for example, Iron, Nickel or Steel. When the second pin 50 is mobilized by an external force, the first pin 30 will remain attracted to the second pin 50, such that no open space between the first pin 30 and the second pin 50 can be formed at the interface surface 60. The magnetic force between the first pin 30 and the second pin 50 shall not be too large that the pin 30 and the pin 50 cannot be separated by the shear force exerted by the turning key 10 in the released position.
As shown in
The magnetized pin may contain magnetic substance, or may be attached with something of a magnetic nature in different shapes. The magnetized pin may also be a whole piece of magnetic substance. The magnetic substance is a substance which displays magnetic properties, for example, magnetic Iron, magnetic Nickel, magnetic Cobalt, magnetic Ferrite, magnet, lodestone or natural magnet. There can be different combinations of the first pin 30 and the second pin 50, for example, a magnetized first pin 30 with a magnetic permeable second pin 50, or a magnetic permeable first pin 30 with a magnetized second pin 50.
As shown in
The magnetic force of the magnet 100 which attracts the second pin 150 and the first pin 130 shall be smaller than the releasing force of the biasing device 28, to avoid the pins from compressing against the biasing device 28 or being attached to the magnet 100. This magnetic force shall also not be too large that the first pin 130 and the second pin 150 can not be separated by the shear force exerted by the turning key 10 to open the pin tumbler lock 15 in the released position.
The embodiments described in this specification and the contents disclosed therein are provided by way of illustration only. The invention can be applied equally well on other types of pin tumbler lock.
While the invention has been described in detail with reference to disclosed embodiments, various modifications within the scope of the invention will be apparent to those of ordinary skill in this technological field. It is to be appreciated that features described with respect to one embodiment typically may be applied to other embodiments.
Number | Date | Country | Kind |
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06113261.9 | Dec 2006 | HK | national |