The present disclosure generally relates to a bumping preventing arrangement. In particular, a bumping preventing arrangement for a lock device, a lock device comprising a bumping preventing arrangement, and a method of controlling a lock device, are provided.
Unauthorized manipulation of lock devices by different types of bumping is a well-known problem for key cylinder locks. Also blocking mechanisms for dead bolts and door handles may be subjected to bumping.
In some prior art lock devices, a certain mechanical force “hill” needs to be passed to bump a transfer member from a locked position to an unlocked position to thereby be able to unlock the lock device without authorization. The transfer member may for example be a blocking member or a coupling member. The mechanical force hill may be the force required to overcome a force from a spring that pushes the transfer member towards the locked position.
In those prior art lock devices, the same mechanical force hill for unauthorized unlocking also needs to be overcome for authorized unlocking of the lock device. In the case of a spring pushing the transfer member towards the locked position, the transfer member needs to be moved against the force of the spring also for authorized unlocking. Thus, authorized unlocking often requires a substantial amount of energy to unlock. This is problematic when the transfer member is driven by a motor, and in particular if the lock device is an energy harvesting lock device with a small battery or with no battery at all.
One object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement improves security of the lock device.
A further object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement provides resistance against bumping of the lock device.
A still further object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement has low power consumption.
A still further object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement has a compact, simple and/or reliable design.
A still further object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement has a compact, simple and/or reliable function.
A still further object of the present disclosure is to provide a bumping preventing arrangement for a lock device, which bumping preventing arrangement solves several or all of the foregoing objects in combination.
A still further object of the present disclosure is to provide a lock device comprising a bumping preventing arrangement, which lock device solves one, several or all of the foregoing objects.
A still further object of the present disclosure is to provide a method of controlling a lock device, which method solves one, several or all of the foregoing objects.
According to one aspect, there is provided a bumping preventing arrangement for a lock device, the bumping preventing arrangement comprising a transfer member having a magnet, the transfer member being movable along an actuation axis between a locked position and an unlocked position; a plurality of electric conductors, each electric conductor enclosing the actuation axis; and a plurality of switches, each switch being associated with a respective electric conductor, and being arranged to selectively close an electric circuit comprising the associated electric conductor such that eddy currents are induced in the electric conductors when the magnet moves along the actuation axis from the locked position towards the unlocked position.
The eddy currents generate a magnetic force on the magnet acting against the movement of the magnet. The magnetic force acts as a brake against movements of the transfer member due to bumping.
The transfer member may move relatively easy during authorized unlocking of the lock device when the switches are open due to the absence of the magnetic force. However, for unauthorized opening or bumping when the switches are closed, the transfer member moves relatively heavy due to the induced eddy currents and the consequential counteracting magnetic force.
The bumping preventing arrangement thus enables a particular “unauthorized force hill” and a particular “authorized force hill”, lower than the unauthorized force hill, to be set. For example, the unauthorized force hill may be the force needed to overcome both the force of an elastic element and the magnetic force from the eddy currents, and the authorized force hill may be the force needed to overcome only the force of the elastic element. Since the force of an elastic element and the magnetic force can be set as desired, e.g. by corresponding dimensioning of the parts, also the unauthorized force hill and the authorized force hill can be set as desired. In this way, a low authorized force hill and a high unauthorized force hill can be set. This enables a high protection against bumping with a low energy consumption. A wide range of tradeoffs between a very high protection against bumping and a very lower energy consumption can also be realized by means of the bumping preventing arrangement.
The selective closing of the switches can be made with very low power consumption. The bumping preventing arrangement thus provides a low power bumping protection based on the eddy current principle.
When the electric circuits are selectively opened by opening of the switches, no eddy currents are induced in the electric conductors when the magnet moves along the actuation axis from the locked position towards the unlocked position. When the switches are open, the switches are in an unlocked state. This may be referred to as an opening mode.
When the switches are closed to close the electric circuits, the switches are in a locked state. This may be referred to as a protection mode. Each switch may be either electrically or mechanically controlled.
Each electric conductor may partly or entirely enclose the actuation axis. Each electric conductor may have the same, or substantially the same, electrical conductivity. The electric conductors may for example be made of copper, gold or silver. The electrical conductivity of the electric conductors may be at least 3×107 σ (S/m) at 20° C., such as at least 4×107 σ (S/m) at 20° C. The bumping preventing arrangement may comprise at least three electric conductors, such as three to six electric conductors.
Due to the cooperation between the electric conductors and the switches to selectively induce eddy currents as a result of movement of the magnet, the bumping preventing arrangement can be miniaturized for various types of lock devices. Thus, the bumping preventing arrangement enables a compact design.
The magnet may be a permanent magnet. The magnet may for example comprise a Neodymium alloy such as a Neodymium-Iron-Boron (NdFeB), or other alloy having a relatively high intrinsic remanence. A relatively high intrinsic coercivity may be used to protect the magnet from being demagnetized by an applied external magnetic field.
The electric conductors may be arranged in a stack. The stack may thus extend parallel with the actuation axis. By arranging the electric conductors in a stack, a tube of electric conductors is formed. A length of the stack along the actuation axis may be larger than a length of the magnet along the actuation axis.
Each electric conductor may extend in a plane substantially perpendicular to, or perpendicular to, the actuation axis. The electric conductors may thus be arranged as, or configured as, a plurality of washers. In this case, each washer may comprise an opening where one of the switches is connected.
The bumping preventing arrangement may further comprise an elastic element arranged to force the transfer member along the actuation axis towards the locked position. The elastic element may for example be a leaf spring or a coil spring.
The transfer member may be constituted by the magnet. Alternatively, the magnet may constitute only a part of the transfer member. That is, the transfer member may comprise the magnet and one or more non-magnetic parts. In any case, the transfer member may be rigid.
The transfer member may be a blocking member. The blocking member may block relative movement between an input member and an output member in the locked position, and unblock relative movement between the input member and the output member in the unlocked position. Thus, in the unlocked position of the blocking member, a movement of the input member is transferred to the output member.
Alternatively, the transfer member may be a coupling member. The coupling member may decouple an input member from an output member in the locked position, and couple the input member to the output member in the unlocked position. Thus, in the unlocked position of the coupling member, a movement of the input member is transferred to output member. The coupling member may thereby function as a clutch.
Each switch may comprise a transistor. The transistor may be controlled by voltage. Alternatively, each switch may be an electromechanical switch or a mechanical switch.
The transistor may be a metal oxide semiconductor field effect transistor, MOSFET, such as N-type metal oxide semiconductor field effect transistor, nMOSFET.
The transistor may be a field effect transistor of the depletion type. The depletion type field effect transistor is normally closed (on). By applying a voltage to the gate, the transistor opens the electric circuit. Depletion type field effect transistors do therefore not consume any power in the locked state. The use of depletion type field effect transistors is therefore advantageous for energy harvesting lock devices which may have limited or no available power in passive mode.
Alternatively, the transistor may be a field effect transistor of the enhancement type. The enhancement type field effect transistor is normally open (off). By applying a voltage to the gate, the transistor closes the electric circuit. Enhancement type field effect transistors do therefore not consume any power in the unlocked state.
The bumping preventing arrangement may further comprise a control system, the control system comprising at least one data processing device and at least one memory having a computer program stored thereon, the computer program comprising program code which, when executed by the at least one data processing device, causes the at least one data processing device to perform the steps of evaluating an authorization request; and commanding each switch to open in response to a granted evaluation of the authorization request. The computer program may further comprise program code which, when executed by the at least one data processing device, causes the at least one data processing device to perform, or command performance of, various steps as described herein.
The control system may further comprise a receiving unit, such as an antenna, for receiving the authorization request. The control system may be configured to determine whether or not authorization should be granted based on the authorization request. If access is granted, e.g. if a valid credential is presented, each switch is commanded to open.
The bumping preventing arrangement may further comprise a printed circuit board, PCB. The control system may be provided on the PCB.
According to a further aspect, there is provided a lock device comprising a bumping preventing arrangement according to the present disclosure. The lock device may comprise an input member and an output member. The output member may be prevented from being moved by movement of the input member when the transfer member is in the locked position. Conversely, the output member may be allowed to be moved by movement of the input member when the transfer member is in the unlocked position.
The lock device may be an energy harvesting lock device. To this end, the lock device may further comprise an electric generator arranged to generate electric energy from movement of the input member. The energy harvesting lock device may not comprise a battery.
According to a further aspect, there is provided a method of controlling a lock device, the method comprising providing a lock device according to the present disclosure; and opening each switch in response to a granted authorization request from a user. If the authorization request is not granted or if no authorization request is received, the each switch remains closed.
Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:
In the following, a bumping preventing arrangement for a lock device, a lock device comprising a bumping preventing arrangement, and a method of controlling a lock device, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.
In
The bumping preventing arrangement 10 further comprises a plurality of electric conductors 20 and a plurality of switches 22. In this specific example, the bumping preventing arrangement 10 comprises six electric conductors 20 and six switches 22. Each electric conductor 20 is associated with one of the switches 22 and each switch 22 is associated with one of the electric conductors 20. Each pair of electric conductor 20 and associated switch 22 encloses the actuation axis 18.
Each electric conductor 20 is arranged in a plane perpendicular to the actuation axis 18 and is shaped as a washer. Each washer comprises a cut-out where the associated switch 22 is positioned. As shown in
In
The switches 22 are here exemplified as field effect transistors of the depletion type, i.e. normally closed (on). Thereby, the switches 22 do not consume any power in the locked states 24.
The bumping preventing arrangement 10 further comprises a control system 26. The control system 26 of this example comprises a data processing device 28, a memory 3o and an antenna 32. The memory 3o has a computer program stored thereon. The computer program comprises program code which, when executed by the data processing device 28, causes the data processing device 28 to evaluate an authorization request received by the antenna 32, and to command each switch 22 to open in response to a granted evaluation request. The authorization request may for example be received by the antenna 32 via Bluetooth Low Energy, BLE. Components of the control system 26 may be arranged on a common PCB.
When the switches 22 are in the locked states 24 to short the electric circuits and the transfer member 12 is attempted to be moved from the locked position 16, eddy currents are created in electric conductors 20 by the moving/changing magnetic field of the magnet 14. The eddy currents generate a magnetic force on the magnet 14 acting against the movement of the transfer member 12. In this way, bumping of the transfer member 12 away from the locked position 16 can be prevented.
When the switches 22 are in the unlocked states 34, each electric circuit around the magnet 14 is open. Consequently, no eddy currents are induced in the electric conductors 20 by movement of the magnet 14 and the magnet 14 is therefore not subjected to any magnetic force from such eddy currents. The transfer member 12 can thereby be moved from the locked position 16 to an unlocked position 36. The switches 22 are thus selectively closed and opened in order to turn on and off, respectively, the eddy currents and the consequential braking magnetic field.
Each spring 48 forces the associated driver pin 46 along an actuation axis 18 into the locked position 16. The springs 48 are examples of elastic elements. The plug 42 is one example of an output member.
The key cylinder lock 38 further comprises a bumping preventing arrangement 10 of the same type as in
In
In order to bump a driver pin 46 from the locked position 16 to the unlocked position 36, both the force of the spring 48 and the magnetic force generated by eddy currents induced in the electric circuits need to be overcome. A sum of these forces constitutes an unauthorized force hill. Moreover, insertion of a key into the plug 42 will be rather heavy when the electric circuits are closed.
When the switches 22 are in the unlocked states 34, each electric circuit around the respective magnets 14 is open. Consequently, no eddy currents are induced in the electric conductors 20 by movement of the magnets 14 and the magnets 14 are therefore not subjected to any magnetic force from such eddy currents. The driver pins 46 can thereby be moved from the locked position 16 to the unlocked position 36 against the forces of the respective spring 48. The force needed for this movement constitutes an authorized force hill, which is lower than the unauthorized force hill.
As shown in
The lock device 52 further comprises a transmission 58. The transmission 58 is configured to transmit a movement of the handle 54 to a movement of the latch bolt 56. To this end, the transmission 58 may for example comprise gear wheels and/or a linkage.
The lock device 52 further comprises an electromechanical actuator 60. The actuator 6o comprises an actuator pin 62. The actuator 6o can move the actuator pin 62 linearly. The actuator 6o is controlled by the control system 26.
The lock device 52 further comprises a blocking member 64 and a spring 48. The spring 48 is arranged between the actuator pin 62 and the blocking member 64. The blocking member 64 is one example of a transfer member. The blocking member 64 is constituted by a magnet 14, here a cylindrical magnet.
The lock device 52 further comprises a bumping preventing arrangement 10 of the same type as in
The lock device 52 may be an energy harvesting lock device. In this case, the control system 26 and the actuator 6o are powered by electric energy harvested by mechanical movement of the handle 54.
In
In
When the switches 22 are in the unlocked states 34, each electric circuit around the magnet 14 is open. Consequently, no eddy currents are induced in the electric conductors 20 by movement of the magnet 14 and the magnet 14 is therefore not subjected to any magnetic force from such eddy currents. Simultaneously with, or after, the switches 22 are switched to the unlocked states 34, the control system 26 commands the actuator 6o to move the actuator pin 62. As shown in
The retracting movement of the actuator pin 62 does not need to overcome the force of the spring 48. In fact, since the spring 48 is compressed when the blocking member 64 is in the locked position 16, the spring 48 initially assists the retraction of the actuator pin 62. Thus, a very low authorized force hill is obtained.
In
The lock device 68 further comprises an electromechanical actuator 60 having an actuator pin 62. The actuator 6o and the actuator pin 62 are of the same type as in
The lock device 68 further comprises a coupling member 74 and a spring 48. The spring 48 is arranged between the actuator pin 62 and the coupling member 74. The coupling member 74 is a further example of a transfer member. The coupling member 74 is constituted by a magnet 14, here a cylindrical magnet.
The lock device 68 further comprises a bumping preventing arrangement 10. The bumping preventing arrangement 10 comprises the coupling member 74 constituted by the magnet 14, a plurality of electric conductors 20, a plurality of switches 22, the spring 48 and the control system 26. The coupling member 74 is enclosed by a plurality of electric circuits, each formed by one of the electric conductors 20 and one of the switches 22. It should be emphasized that the lock device 68 in
The lock device 68 may be an energy harvesting lock device. In this case, the control system 26 and the actuator 6o are powered by electric energy harvested by rotation of the knob 70.
In
In
When the switches 22 are in the unlocked states 34, each electric circuit around the magnet 14 is open. Consequently, no eddy currents are induced in the electric conductors 20 by movement of the magnet 14 and the magnet 14 is therefore not subjected to any magnetic force from such eddy currents. Simultaneously with, or after, the switches 22 are switched to the unlocked states 34, the control system 26 commands the actuator 6o to move the actuator pin 62. As shown in
In
While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.
Number | Date | Country | Kind |
---|---|---|---|
2050450-2 | Apr 2020 | SE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2021/060194 | 4/20/2021 | WO |