GB2586018A

GB2586018A - Electrically-Operated Lock

Info

Publication number: GB2586018A
Application number: GB1910769.7A
Authority: GB
Inventors: Colin Powell Simon
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-29
Filing date: 2019-07-29
Publication date: 2021-02-03
Also published as: GB201910769D0

Abstract

The electrically-operated lock 6 comprises a piston 2 with a radially-projecting tab 8 within a cylinder and a motor 42 coupled to the piston, the cylinder including a rotational chamber 28 and a longitudinal channel 30; wherein when the tab is located within the chamber, the piston can rotate within the cylinder; when the tab is aligned with the channel, the piston can be displaced axially within the cylinder and the lock is unlocked; and when the tab is out of alignment with the channel, the piston is prevented from displacement and the lock is locked; the motor rotates the tab. The lock may further comprise a shunt 14 comprising a spring 16 to bias the piston towards the chamber in its locking configuration. The lock may comprise a cam 48 and follower 50 which are moved by the motor or by a manual override. The piston prevents the movement of slider 60 by engagement of blocking element 10 in v-shaped recess 62 when in the locked configuration.

Description

Electrically-Operated Lock The present invention relates to an electrically-operated lock and, in particular, to a lock which has a relatively low power consumption.

The use of motors and solenoids to control locking systems is well known.

The known apparatus are typically either based on an electromagnetic clamp that is added to a door, or an electro-mechanical device that emulates traditional mechanical lock mechanisms, wherein a blocking member is received into a fixed receiver until retracted by a key.

A problem with the use of solenoids to operate a lock mechanism is that they are relatively inefficient as a result of the airgap required to provide movement of the solenoid. This airgap requires significant electrical power to be passed through the excitation coil to initiate movement.

However, solenoids are useful, as they can be biased to return to their starting position or they can include a magnet to retain the solenoid in one of two positions. Such solenoids are referred to as "bistable". However, solenoid devices can be sensitive to impacts and external magnetic fields.

Motor actuators require electrical power to function, but tend to be more efficient that solenoids, owing to the closer coupling of the activation coils and the movement magnets. However, the use of small, and consequently low force, motors can lead to problems, particularly when the door is under an external load or distorted, as the motor may lack the ability to generate the force necessary to operate the lock. Additionally, the smaller the motor and the lock mechanism, the more susceptible the system is to contamination.

In view of the above, there is a need for a robust, electrically-operated lock which has a relatively low power consumption and manufacturing cost.

According to a first aspect of the invention, there is provided an electrically-operated lock comprising a piston located within a cylinder and an electric motor operatively coupled to the piston; wherein the piston includes a radially projecting tab; the cylinder includes a rotational chamber and a longitudinal channel in communication with one end of the rotational chamber and extending longitudinally away from the rotational chamber; wherein when the radially projecting tab is located within the rotational chamber, the piston is capable of rotation within the cylinder about a longitudinal axis of the cylinder; when the radially projecting tab is aligned with the longitudinal channel, the piston is capable of axial displacement within the cylinder; and when the radially projecting tab is out of alignment with the longitudinal channel, the piston is prevented from axial displacement within the cylinder; the motor rotates the projecting tab when it is located within the rotational chamber from a locked configuration in which the projecting tab is out of alignment with the longitudinal channel to an unlocked configuration in which the radially projecting tab is aligned with the longitudinal channel.

As the motor merely rotates the radially projecting tab from an orientation in which it is out of alignment with the longitudinal channel (i.e. its locked configuration) to an orientation in which it is aligned with the longitudinal channel (i.e. its unlocked configuration), the motor may be a relatively small, low power motor which uses relatively little power. Furthermore, in situations in which the door is under load or distorted, this tends to have relatively little impact on the force required to rotate the piston about the longitudinal axis of the cylinder when the radially projecting tab is in the rotational chamber. Accordingly, the motor need not work against a load placed on the door.

It will be appreciated that when the radially projecting tab is in its unlocked configuration and the piston is able to slide axially within the cylinder, the piston may be retracted into a body portion of the lock, which in turn may permit the door to be opened.

In an embodiment of the invention, the piston is prevented from rotating within the cylinder about the longitudinal axis of the cylinder when the radially projecting tab is located within the longitudinal channel.

In order that the piston is not capable of axial displacement or movement within the cylinder when the radially projecting tab is out of alignment with the longitudinal channel, the rotational chamber may include a locking wall extending from one side of the longitudinal channel, the projecting tab engages the locking wall when out of alignment with the longitudinal channel, and the engagement between the projecting tab and the locking wall prevents axial displacement of the piston within the cylinder. The locking wall is suitably substantially aligned with the open top of the longitudinal channel and extends around at least a portion of the circumference of the rotational chamber.

In an embodiment of the invention, the projecting tab of the piston is biased towards the rotational chamber. The lock may include an axial biasing element which generates the axial biasing force. In certain embodiments, the rotational chamber may be disposed towards one end of the cylinder and the piston may be biased towards that end of the cylinder. This makes it more difficult to "bump" the piston into a retracted configuration within a body of the lock, as the biasing force will counteract the "bumping" force. It is a convenient feature of the present invention that the rotary moment of inertia of the assembly is low and so the force required to prevent bumping is relatively small, avoiding the need for heavy springs and a subsequently stronger motor arrangement.

In a further embodiment of the invention, the radially projecting tab of the piston is rotationally biased to its locked configuration. Accordingly, when the radially projecting tab of the piston is disposed within the rotational chamber, the tab is biased to an orientation in which it is out of alignment with the longitudinal channel. The lock may include a rotational biasing element which generates the rotational biasing force.

The combination of an axial biasing element, which biases the radially projecting tab to the rotational chamber, and a rotational biasing element, which biases the radially projecting tab to an orientation in which it is out of alignment with the longitudinal channel, results in an arrangement which resists the unintended or unwanted unlocking of the lock.

The combination of an axial biasing element and a rotational biasing element may be provided by a shunt which includes a spring and a shunt body having angled contact face which contacts a surface (e.g. an end surface) of the piston. The spring provides the axial biasing force which biases the radially projecting tab to the rotational chamber and the angled contact face of the shunt body provides a rotational biasing force to the piston, which in turn biases the radially projecting tab out of alignment with the longitudinal channel when the tab is disposed within the rotational chamber. In an embodiment of the invention, the angled contact face of the shunt body may define a helical surface. In a further embodiment of the invention, a contact surface of the piston (e.g. an end surface of the piston) may define a complementary helical surface, whereby an axial force exerted on the shunt body generates a torque moment on the piston.

In order that the torque generated between the angled contact face and the piston provides a torque moment on the piston, the shunt body is suitably restrained from rotation relative to the cylinder. Thus, the shunt body may be rotationally fixed or locked relative to the cylinder.

In an embodiment of the invention, the lock includes a lock body and the piston includes a blocking element, wherein the blocking element projects from the lock body when the projecting tab is in its locked configuration and the blocking element may be retracted into the lock body when the projecting tab is in its unlocked configuration. The blocking element may be carried by one end of the piston or it may be defined by one end of the piston. The blocking element may be received by a fixed receiver when the lock is in its locked configuration (i.e. when the projecting tab is in its locked configuration), which prevents the relative movement of a mating part, such as a door. Thus, in its locked configuration the blocking element prevents the door (or other mating part) from being opened; Additionally, the blocking element may be retracted from the fixed receiver when the lock is unlocked, which permits the relative movement of the mating part, for example, permitting the opening and closing of the door.

In an embodiment of the invention, the rotational chamber includes a stop wall at the opposite end of the chamber to the longitudinal channel which prevents axial displacement of the projecting tab. Such an arrangement may define a maximum projection of the blocking element from the lock body, as it defines one end of the range of axial displacement of the piston within the cylinder. It will be appreciated that a stop surface provided at a distal end of the longitudinal channel (i.e. the end of the longitudinal channel which is furthest from the rotational chamber) defines the other end of the range of axial displacement of the piston within the cylinder.

The motor may be a rotational electric motor and include a cam which is operatively coupled to the projecting tab when the projecting tab is located within the rotational chamber, the cam having a first orientation which permits rotation of the projecting tab out of alignment with the longitudinal channel, and a second orientation which aligns the projecting tab with the longitudinal channel. According to this embodiment, rotation of the motor causes a corresponding rotation of the cam, which in turn causes rotation of the radially projecting tab within the rotational chamber.

Such an arrangement permits the motor to be arranged parallel to the longitudinal axis of the cylinder, which results in a compact arrangement of the lock, and is useful in converting the rotation of the motor to a rotation of the radially projecting tab within the rotational chamber In an embodiment of the invention, the angle between the first and second orientations is less than 180°. For an example, the angle may be less than 120°, less than 90°, less than 45° or less than 30°. Thus, the angle may be between 10° and 90°, such as between 10° and 45° or between 10° and 30°. The skilled person will appreciate that the smaller the angle between the first and second orientations, the less power the motor will require in order to urge the radially projecting tab from its locked configuration to its unlocked configuration. In an embodiment of the invention, a relatively small rotation of the motor will cause the projecting tab to move from its unlocked configuration to its locked configuration. However, optionally, there is sufficient rotation of the projecting tab to present sufficient material of the projecting tab in contact with the locking wall that the locking tab resists fracture or deformation under an axial load when the assembly is stressed.

The cam may directly engage or contact the radially projecting tab in the rotational chamber or it may engage or contact the radially projecting tab via a cam follower. Thus, the lock may include a cam follower disposed between the cam of the motor and the projecting tab of the piston; the motor is arranged such that the rotational axis of the motor is parallel to the longitudinal axis of the cylinder; the cam follower is displaced radially relative to both the rotational axis of the motor and the longitudinal axis of the cylinder.

In an embodiment of the invention, the cam follower is pushed but not pulled by the cam such that the motor is capable of returning the cam to its first orientation when the radially projecting tab is located within the longitudinal channel. In such an embodiment, the radially projecting tab will be urged to return to its locked configuration by the energy stored in the shunt when any force maintaining the radially projecting tab in the longitudinal channel is removed.

In an embodiment of the invention, the lock further includes a manual over-ride, wherein cam follower is disposed within a cam follower channel; the manual over-ride includes an closable aperture located at one end of the cam follower channel; and a rod which extends through the aperture and engages the cam follower, wherein the rod is capable of urging the cam follower against the projecting tab of the piston and rotating the projecting tab into alignment with the longitudinal channel. In such an arrangement, the cam follower may be urged to rotate the radially projecting tab manually by the rod (i.e. without use of the motor). This permits the lock to be unlocked in situations where power to the motor is interrupted or insufficient, or where the motor is faulty, as well as permitting remote operation of the lock assembly via a cable or similar, for example to effect unlocking of the lock assembly from within a secure area. The cam follower channel is suitably a straight channel which is arranged in a plane that is perpendicular to the longitudinal axis of the piston.

Although an electric rotational motor has been discussed hereinabove, it will be appreciated that the motor simply needs to be capable of rotating the radially projecting tab when this is disposed within the rotational chamber. Accordingly, the motor may be a geared or direct acting electrical motor; a solenoid with or without a latching magnetic circuit; a voice coil actuator; a shape memory alloy actuator; a pneumatic piston; a hydraulic piston; a lever operating a Bowden cable; a piezo-electric actuator; or a bimetallic strip. It will be appreciated that the motor may operate via a rotational force or a linear force.

In a further embodiment of the invention, the lock may include a second piston. Optionally, the second piston is axially aligned with the first piston within a lock body. In a yet further embodiment, the first and second pistons both include a blocking element located at one end thereof, wherein the blocking element of the first piston projects from a first end of a lock body when in it locked configuration and the blocking element of the second piston projects from an opposite end of the lock body in its locked configuration.

The skilled person will appreciate that the features described and defined in connection with the aspect of the invention and the embodiments thereof may be combined in any combination, regardless of whether the specific combination is expressly mentioned herein. Thus, all such combinations are considered to be made available to the skilled person.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings as follows.

Figure 1 is a perspective view of a piston and shunt which form part of a lock according to a first embodiment of the invention; Figure 2 is a perspective view of a lock body and shunt which form part of the lock according to the first embodiment of the invention; Figure 3 shows the forces exerted on the piston and shunt shown in Figure 1; Figure 4 is a perspective view of piston shown in Figure 1, an electric motor and a cam follower which form part of the lock according to the first embodiment; and Figure 5 is a cross-sectional view of the lock according to the first embodiment.

For the avoidance of doubt, the skilled person will appreciate that in this specification, the terms "up", "down", "front", "rear", "upper", "lower", "width", etc. refer to the orientation of the components as found in the example when installed for normal use as shown in the Figures.

Figure 1 shows a piston 2 and a shunt 4 which are used in an electrically-operated lock 6.

The piston 2 is substantially cylindrical in shape and includes a radially projecting tab 8 located towards the top end of the piston 2. At the top end of the piston 2 is an integrally formed blocking element 10 and at the bottom end of the piston 2 is defined a helical wall 12.

The shunt 4 comprises a shunt body 14 and a helical spring 16. The shunt body 14 includes a locating lug 18 which extends radially therefrom. The top end of the shunt body 14 defines a helical wall 20 which is complementary to the helical wall 12 defined by the bottom end of the piston 2.

Figure 2 shows a lock body 22 which defines therein a cylinder 24 which is open at its top end 26. Towards the top end 26 of the cylinder 24 is defined a rotational chamber 28 in which a portion of the cylinder wall has been removed. In communication with the rotational chamber 28 and extending downwardly therefrom is a longitudinal channel 30 which is arranged to be parallel to the longitudinal axis of the cylinder 24. The lock body defines a locking wall 40 which extends radially outwards from the open end of the longitudinal channel 30 and defines a bottom wall of the rotational chamber 28.

As seen in Figure 2, the shunt 4 is located at the bottom of the cylinder 24. Towards the bottom end of the cylinder 24, the lock body 22 defines a recess 32 which receives therein the locating lug 18 in such a way that the locating lug is able to move axially (i.e. parallel to the longitudinal axis of the cylinder 24) within the recess 32, but is prevented from rotation relative to the lock body 22.

The bottom end of the cylinder 24 terminates in a floor 34 with which the spring 16 is engaged.

At the end of the rotational chamber 28 which is opposite to the end from which the longitudinal channel 30 depends, the lock body 22 defines an aperture 36 which is closed by a lockable cover 38. The purpose of the aperture 36 and lockable cover 38 will be described below.

Figure 3 shows that a torque moment T is generated on the piston 2 when a force F is applied downwardly against the blocking element 10. This is as a result of the interengagement of the complementary helical portions 12, 20 of the piston 2 and the shunt body 14.

Figure 4 shows a motor, cam and cam follower arrangement which is used to drive the radially projecting tab 8 to rotate when the tab 8 is disposed within the rotational chamber 28. A motor 42 is arranged parallel to the cylinder 24 and in use is located within a motor recess 44 defined by the lock body 22. A drive shaft from the motor passes through an exit port 46 from the motor recess 44 such that a cam 48 carried by the drive shaft is located within the rotational chamber 28. The cam 48 is capable of rotation within the rotational chamber 28.

A cam follower 50 operatively couples the cam 48 to the radially projecting tab 8. The cam follower 50 includes at one end thereof an upper leg 52 and a lower leg 54 which define therebetween a gap. The cam 48 is located in the gap defined between the legs 52, 54. At the opposite end of the cam follower 50 is defined a contact surface 56, which contacts the radially projecting tab 8.

In this arrangement, the motor 42, via the cam 48 and cam follower 50 is able to rotate the radially projecting tab against the torque moment generated by the coupled helical surfaces and the force exerted by the spring 16 against the shunt body 14. In other words, when the motor rotates clockwise (as shown in Figure 4), the cam 48 urges the cam follower 50 to move radially towards the piston 2. The contact surface 56 urges the radially projecting tab 8 also to rotate in a clockwise direction. The helical walls 12, 20 cooperate when the piston 2 is rotated clockwise and the shunt body 14 is urged downwards, thereby compressing the spring 16.

The radially projecting tab 8 is rotated by the motor 42 as described above until it is in alignment with the longitudinal channel 30, in which orientation, the piston 2 is able to move axially downwards within the cylinder 24. As the piston 2 moves downwardly within the cylinder 24, the blocking element 10 is retracted within the lock body and the lock is in an unlocked configuration.

When the motor 42 is then rotated in a counter-clockwise direction, the torque moment T exerted on the piston 2 by the shunt body 14, as a result of the force exerted by the spring 16 and the arrangement of helical walls, causes the radially projecting tab 8 to urge the cam follower 50 to follow the cam 48. As the radially projecting tab 8 rotates counter-clockwise within the rotational chamber 28, the tab 8 is no longer aligned with the longitudinal channel 30. When the tab 8 is out of alignment with the longitudinal channel, the bottom surface of the radially projecting tab 8 engages the locking wall 40, which prevents any downward displacement of the piston 2 within the cylinder 24. With the radially projecting tab 8 disposed within the rotational chamber 28, the blocking element 10 projects upwardly from the open end 26 of the cylinder 24. This arrangement defines a locked configuration when the radially projecting tab 8 is out of alignment with the longitudinal channel 30, the locking wall 40 prevents the downward displacement of the piston 2 within the cylinder 24, and the blocking element 10 is retained in a position in which it projects from the open end 26 of the cylinder 24. Thus, when the motor is rotated such that the cam 48 is urged away from the radially projecting tab 8, the torque exerted on the shunt body 14 on the piston 2 causes the piston 2 to rotate as soon as the projecting tab 8 is within the rotational chamber 28, thus automatically configuring the projecting tab 8 in its locked configuration.

In the event that power is lost to the motor 42 or the motor 42 fails, the lock may be manually released. To manually release the lock, the lockable cover 38 is manually opened (e.g. via a key) and a rod (not shown) is inserted through the aperture 36. The rod then contacts the bottom leg 54 of the cam follower 50 and may be used to urge the cam follower towards the piston 2. As noted above, the movement of the cam follower 50 towards the piston 2 causes the radially projecting tab 8 to rotate until it is aligned with the longitudinal channel 30. In this orientation, the piston may be moved downwardly within the cylinder, which in turn retracts the blocking element 10 into the lock body 22 and configures the lock in its unlocked configuration.

When the rod is retracted from the aperture 36, the spring 16 returns the radially projecting tab 8 to the rotational chamber 28 and the torque moment exerted on the piston urges the piston to rotate such that the radially projecting tab 8 is out of alignment with the longitudinal channel 30 and the lock is returned to its locked configuration.

Figure 5 show a lock assembly 6 in its locked configuration with the blocking element 10 projecting from the open end 26 of the cylinder 24.

A slider 60 is provided which includes a V-shaped recess 62, which is sized and configured to receive therein the blocking element 10. The slider 60 is arranged such that it is constrained by a restraining wall 64 to move only in a horizontal plane. When the lock assembly 6 is in its locked configuration, the slider is prevented from horizontal movement by the blocking element 10 being located within the V-shaped recess 62. However, when the lock assembly 6 is in its unlocked configuration and the slider 60 is urged in a horizontal direction, the blocking element 10 is urged downwards into the cylinder 24 by the force exerted on it by one of the walls of the V-shaped recess 62 and the slider may be removed from the lock assembly 6.

The skilled person will appreciate that alternative blocking elements may be used with the arrangement of the invention and that different receiving members may be used to receive the blocking element in accordance with the invention as defined in the claims appended hereto.

An advantage of the invention is the robust operation that may be achieved with a small rotation of the motor 42, which minimises the electrical energy needed to change the configuration of the lock 6. For example, in an embodiment of the invention in which the piston 8 has a diameter of 8mm and the radially projecting tab 8 has a length of 6.5mm and a thickness of 3mm, the motor 42 needs only rotate the tab 8 by 15° to move it out of alignment with the longitudinal channel 30. An example motor may have an output speed of 120rpm, which equates to a rotational speed of 720° per second. On the basis that the motor needs only to rotate the tab 8 by 15°, the motor would need to be energised for just 20 milliseconds to unlock the lock assembly 6. Assuming that the motor has a power consumption of 40mA at 2V, the unlocking of the lock assembly would require just 2.5mJ.

Claims

Claims 1. An electrically-operated lock comprising a piston located within a cylinder and an electric motor operatively coupled to the piston; wherein the piston includes a radially projecting tab; the cylinder includes a rotational chamber and a longitudinal channel in communication with one end of the rotational chamber and extending longitudinally away from the rotational chamber; wherein when the radially projecting tab is located within the rotational chamber, the piston is capable of rotation within the cylinder about a longitudinal axis of the cylinder; when the radially projecting tab is aligned with the longitudinal channel, the piston is capable of axial displacement within the cylinder; and when the radially projecting tab is out of alignment with the longitudinal channel, the piston is prevented from axial displacement within the cylinder; the motor rotates the projecting tab when it is located within the rotational chamber from a locked configuration in which the projecting tab is out of alignment with the longitudinal channel to an unlocked configuration in which the radially projecting tab is aligned with the longitudinal channel.
2. An electrically-operated lock according to claim 1, wherein the rotational chamber includes a locking wall extending from one side of the longitudinal channel, the projecting tab engages the locking wall when out of alignment with the longitudinal channel, and the engagement between the projecting tab and the locking wall prevents axial displacement of the piston within the cylinder.
3. An electrically-operated lock according to Claim 1 or Claim 2, wherein the projecting tab of the piston is biased towards the rotational chamber.
4. An electrically-operated lock according to any of Claims 1 to 3, wherein the radially projecting tab of the piston is rotationally biased to its locked configuration.
5. An electrically-operated lock according to Claim 3 or Claim 4, wherein the lock includes a shunt comprising a spring and a shunt body having an angled contact face, wherein the spring of the shunt biases the piston towards the rotational chamber, the angled contact face of the body engages one end of the piston and the angled contact face of the body provides a torque that urges the projecting tab out of alignment with the longitudinal channel when the tab is located within the rotational chamber.
6. An electrically-operated lock according to Claim 5, wherein the shunt is rotationally fixed relative to the cylinder.
7. An electrically-operated lock according to any of Claims 1 to 6, wherein the piston includes a blocking element and the blocking element projects from a lock body when the projecting tab is in its locked configuration and the blocking element may be retracted into the lock body when the projecting tab is in its unlocked configuration.
8. An electrically-operated lock according to any of Claims 1 to 7, wherein the rotational chamber includes a stop wall at the opposite end of the chamber to the longitudinal channel which prevents axial displacement of the projecting tab.
9. An electrically-operated lock according to any of Claims 1 to 8, wherein the motor includes a cam which is operatively coupled to the projecting tab when the projecting tab is located within the rotational chamber, the cam having a first orientation which permits rotation of the projecting tab out of alignment with the longitudinal channel, and a second orientation which aligns the projecting tab with the longitudinal channel.
10. An electrically-operated lock according to Claim 9, wherein the angle between the first and second orientations is less than 180°
11. An electrically-operated lock according to Claim 10, wherein the angle between the first and second orientations is between 10° and 45°.
12. An electrically-operated lock according to any of Claims 9 to 11, wherein the lock includes a cam follower disposed between the cam of the motor and the projecting tab of the piston; the motor is arranged such that the rotational axis of the motor is parallel to the longitudinal axis of the cylinder; the cam follower is displaced radially relative to both the rotational axis of the motor and the longitudinal axis of the cylinder.
13. An electrically-operated lock according to Claim 12, wherein the lock further includes a manual over-ride, wherein cam follower is disposed within a cam follower channel; the manual over-ride includes an closable aperture located at one end of the cam follower channel; and a rod which extends through the aperture and engages the cam follower, wherein the rod is capable of urging the cam follower against the projecting tab of the piston and rotating the projecting tab into alignment with the longitudinal channel.
14. An electrically-operated lock according to Claim 12 or Claim 13, wherein the cam follower is pushed but not pulled by the cam such that the motor is capable of returning the cam to its first orientation when the radially projecting tab is located within the longitudinal channel.
15. An electrically-operated lock according to any of Claims 1 to 14, wherein the lock includes a second piston, wherein the second piston is axially aligned with the first piston within a lock body, the first and second pistons both include a blocking element located at a respective end thereof, and wherein the blocking element of the first piston projects from a first end of a lock body when in it locked configuration and the blocking element of the second piston projects from an opposite end of the lock body in its locked configuration.