WO2000079056A1

WO2000079056A1 - Access control

Info

Publication number: WO2000079056A1
Application number: PCT/GB2000/002253
Authority: WO
Inventors: Gary Bowles
Original assignee: Gary Bowles
Priority date: 1999-06-21
Filing date: 2000-06-21
Publication date: 2000-12-28
Also published as: GB0103958D0; AU5543500A; GB9914327D0; GB2356002B; GB2356002A

Abstract

Raisable and lowerable bollard or other access control device has a drive mechanism (6 - 13) normally powered from a local source of power (11) to raise and lower an operative access obstructing part (1). The drive mechanism (6 - 13) relies on mechanical engagement between operative parts (13 etc) that does not obstruct unpowered movement of access part (1) if one of its said operative parts (13) is released, as available using non-self-sustaining leadscrew and nut mechanisms and locking/unlocking (17) of rotation for the leadscrew (13).

Description

TITLE: ACCESS CONTROL

DESCRIPTION

FIELD OF INVENTION

This invention relates to retractable access control devices, such as bollards etc, for such as vehicles etc. BACKGROUND TO INVENTION

There are many places, such as private car parks, town centres, stadia, etc., where retractable bollards are useful, being lowered for permitted vehicular access and raised to prevent access by unauthorised vehicles, usually locked to prevent removal . Known bollards are generally of a nature comprising a tube located in the ground with its upper end open substantially at ground level, and a post slidably mounted for vertical movement within the tube from a lower position at least substantially enclosed within the tube and an upper position upstanding therefrom.

Known manual versions have some form of a handle for raising the post and locking means for securing it in the upstanding position. Known automatic versions have driven raising and lowering means usually of pressure-fluid operated nature including a ram extending longitudinally within the tube and fixed with respect to either the tube or the post to move the post relative to the tube. Pneumatic or hydraulic rams rely upon maintaining fluid pressure to lock the post in the upstanding position, and have the disadvantage that, in the event of a fault, the post can only be lowered by access to the powering compressor or hydraulic motor to release the pressure manually via a release valve; an often complicated procedure that, once completed, means the post cannot be raised until the fault has been repaired. Alternative electro-mechanical actuating means of conventional power jack type are very slow and/or prone to damage if of ball- screw nature and also cannot be manually operated without fitting special clutches.

Generally, known manual and automatic bollards both have the disadvantage that, without substantial redesign, neither can be converted to the other, i.e. manual-to- automatic or automatic-to-manual. Moreover, requirement to instal below ground level makes such conversion difficult and expensive. As automatic bollards are usually more expensive than manual ones, it is common to specify installations with a mixture of both types, and effectively reinforcing requirement for two different types of bollard. It is one object of this invention to provide a cost- effective bollard design that is inherently capable of either manual or automatic operation. SUMMARY OF INVENTION

According to one aspect of the present invention there is provided an extensible and retractable bollard comprising a tube or sleeve to be located in the ground with its upper end open substantially at ground level, a post slidable within the tube from a lower position at least substantially enclosed within the tube or sleeve, locking means to secure the post at least said in upper position, and a drive mechanism within the tube or sleeve to move the post relative to the tube or sleeve when powered, the drive mechanism being such that mechanical engagement between its operative parts does not obstruct unpowered movement of the post if one of its said operative parts is released, and the locking means being releasably operative relative to said one operative part. Preferably such extensible and retractable bollard further comprises means to prevent the post from being removed other than by authorised personnel .

In a preferred embodiment the drive mechanism is of leadscrew nature with associated drive nut where the leadscrew is characterised by the following equation: - μ <_. Cosα.Tanλ Equation 1 where : - o. = Flank Angle μ Coefficient of Friction λ = Lead Angle and: - λ = Tan^"1 [Lead/πd] Equation 2 where : - Lead = Number of Starts x Thread Pitch d = Basic Pitch Diameter

The normal principle and practice, so far as I am aware, concerning leadscrew operation is that if the nut is rotated and the lead screw is prevented from turning the resulting internal forces on the thread will cause the lead screw to move through the nut; and that when the nut is no longer rotated and the leadscrew is released, i.e. nominally free to turn, it will not actually do so and the relative position of the leadscrew to the nut will be maintained even if non-destructive force is applied, i.e the mechanism is self-containing up to destruction. This is, of course, the principle behind simple mechanical car j acking systems .

However, if the conditions that satisfy Equations 1 and 2 are met, whilst the same result applies if the nut is rotated and the leadscrew is prevented from turning, the result when the leadscrew is released, is different as the leadscrew will turn quite readily, even to the point where simple force of gravity will cause a vertical leadscrew to spin back down through the nut to its lowest available position, i.e. the system is not self-sustaining. Likewise, if a force equivalent to or greater than gravity is applied in the opposite direction, for example by manually pulling the leadscrew, and the leadscrew is free to rotate, then it will again spin in the nut and a normally vertical leadscrew will rise. However, if both the leadscrew and the nut are prevented from turning, then their relative positions will be maintained whatever non- destructive force is applied and the system is effectively locked.

Thus, if such a leadscrew and nut is employed in the drive mechanism for an extensible and retractable bollard, typically with the leadscrew inside the bollard post, it follows that the same bollard can readily be operated both manually and automatically.

It is further to be appreciated that drive mechanisms as herein envisaged have other applications, including as to operation of other access control devices, such as swinging arm barriers needing to be raised and lowered and/or pivotting wedges also needing to be controlled to be raised out of ground level and lowered back.

Preferred leadscrew drive mechanisms hereof are readily applied to shorter counter-weighted ends of swinging arm barriers, and directly to hollow pivotting wedges from within.

In a preferred mechanism, the leadscrew nut is housed in a drive mechanism body along with means to rotate the nut, preferably a worm gear co-acting with an appropriate gear form cut into the edge of the nut. Suitable drive means to rotate such a worm gear includes an electric motor, say with appropriate reduction gearing, for example, including a spur gear fixed to the worm gear shaft and a pinion fixed to the motor shaft. Such gearing is preferably configured so that it cannot be reverse driven unless power is supplied, thus acting as a lock to prevent the leadscrew nut from turning. Electric motor power is preferably provided by an electric battery, though other suitable power supply may be employed, for example, mains electricity or solar power.

Suitable control means enables the drive means to be operated to move the leadscrew between two predetermined positions with respect to the nut. Preferred electronic control means is intelligent as to the position or state of the leadscrew. Position and movement of the leadscrew can be monitored by the current drawn by said electric drive motor, at least as to reaching a limit of travel with respect in either direction and also if, for any reason, its movement is unduly resisted or obstructed. Preferably, such control means can distinguish between end of travel and encountering an obstruction; and, in the event of the latter, can be arranged automatically to reverse the leadscrew movement, for at least a short distance before stopping. Such momentary reversal of the leadscrew can usefully prevent damage to associated bollard, swinging arm, pivotting wedge or whatever, and to the drive means or obstruction. The normal limits of travel for the leadscrew, thus bollard post etc, may be set by engagement of suitable resilient end stops.

Other embodiments are, of course, feasible using photo-detectors, micro-switches, timers or any other suitable means .

Preferred control means includes means to facilitate operation by a user. This is readily effected by means of a radio receiver adapted to receive a predetermined coded radio signal from an associated transmitter. Other suitable means may however be employed, for example, a remotely sited switch or sensor or other transmitter/receiver combinations .

One preferred implementation is as a self-contained bollard affording an enclosure for an electrically powered mechanism and its battery power supply, with control from a remote control unit transmitting a coded signal.

The control unit may be mounted in a vehicle or handheld, and includes electronic circuitry controlling a transmitter which sends a code when a control (e.g. a push button) on the control unit is operated. The code transmitted may be unique to one bollard, or may be a master code relating to a group of bollards etc, permitting management over-ride e.g. in car parks. The code may be either pre-set in manufacture or may be installed when the unit is first operated or commanded to do so by the operator, e.g. by setting a switch. If for any reason a new code is required for instance a lost key fob or change of operator, a new code can be supplied.

A receiver in the unit may monitor either continuously or for pre-determined timed intervals for transmissions, and, on receipt of a valid code, operate the mechanism to either raise or lower the bollard post etc. Irrespective of the initial position of the bollard post etc, a single control unit signal may cause the bollard post etc to be moved to the opposite limit of travel. If vehicle sensing equipment, for instance pressure pads, optical beams, inductive sensors, capacitive sensors, magnetic sensors, rf detectors or any other type of sensor or detector is used automatically to determine when it is safe to raise the bollard post etc and so raise it, each control unit signal will always lower the bollard post etc, or can be arranged so to do even if the bollard post etc is only partly raised.

Where power for operation of the unit is provided by internal rechargeable batteries, and the control signal receiver is powered up to listen for transmissions for a fraction of each second, battery life is significantly increased. Indeed, until a valid signal is received, all other circuits can be kept in a very low power or "sleep" mode to reduce battery drain even further, and battery life may well be extendable to over three years .

In the event of a failure of remote operation, for example because of discharged batteries in the bollard etc or the transmitter, or through malfunction, manual operation requires only use of such as a key or specially adapted tool that allows access to release latching or locking for the leadscrew against spinning in the bollard post etc.

A bollard hereof may be provided with biasing means for biasing its post towards its upstanding position, say by a compression spring, although other biasing means may be used such as gas cylinders, constant tension spring or extension spring. The provision of a biasing means can ensure that little, if any, effort is required by a user to lift the post into its raised position. Where automatic lowering and raising is deployed, such biasing means can ensure that little force is required from the drive mechanism in order to raise and lower the bollard post, with even greater extension of battery life. Similar provisions can be made relative to drive mechanisms hereof as applied to swinging arms, pivotting wedges or whatever.

In summary, use as a drive mechanism of a high lead angle leadscrew, means the same bollard etc can be used to operate automatically or manually. Also the raise time of the bollard post is much shorter than for prior known geared systems; and unlike other considered high speed mechanical drives, such as ballscrews, the arrangement is mechanically robust. If the leadscrew is prevented from turning, the bollard post etc cannot be raised or lowered and is therefore locked. Unlike other bollards etc this means a separate locking mechanism is not required.

As the manual version or option uses the leadscrew to support and lock the bollard etc, when it is required to lower or raise the bollard etc, the leadscrew provides a controlled support so that, unlike other manual posts etc, the user does not have to support the full weight of the post etc. This means that much larger dimension bollards etc are possible without risk of injury to the user. Outside shop fronts, bollards etc hereof could be installed to deter ram raiders, and could readily be linked to alarm systems for activation if the alarm goes off. BRIEF DESCRIPTION OF DRAWINGS

Specific exemplary implementation for the invention is now described with reference to and as shown in the accompanying drawings in which:-

Figures 1A-C are outline longitudinal sectional extended retracted and detail views of a bollard, with some details emphasised or omitted for clarity; Figures 2A, B are outline plan and scrap sectional views showing more detail of locking means to prevent the post from being removed from the tube;

Figures 3A, B are detail sectional views for variant belt drive; Figures 4 and 5A, B are outline indications of drive mechanisms hereof applied to swinging arm and pivotting wedge devices; and

Figure 6 is an outline circuit diagram for control circuitry. DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Referring to Fig. 1, a retractable post 1 is accommodated in a preferably close-fitting tube or sleeve 2 for movement between an extended position as shown in Fig. 1A and a retracted position as shown in Fig. IB. The tube or sleeve 2 is fixed to a base plate 3 in turn secured to one end of an internal end-flanged tube 4. The tube 4 acts as a guide mandrel for post biasing spring 5 and affords an apertured attachment plate for drive mechanism body 6, containing a leadscrew nut and worm gear on shaft 7 for driving the leadscrew nut. A spur gear 8 fixed to the worm gear shaft 7 applies rotary drive by co-operation with free spur gear 9 meshing with pinion 10 fixed to the output shaft of motor 11. This arrangement of spur gears and pinion could be replaced by any suitable alternative drive arrangement, for example, a belt and pulley drive, see Figures 3A, B for tensioned belt 9B. Spring collar 12 locates and seats the spring 5 in providing upward bias to the inner end of the hollow post 1. Leadscrew 13 is involved in both of locking and moving the post 1. The leadscrew 13 extends through the leadscrew nut in the body 6 and into bearing assembly 14 internal of the post 1. An inner race of the bearing 15 is shown fixed to turned-down end of leadscrew 13, with the outer race of bearing 15 fixed to a bottom plate of the bearing assembly 14. A top plate of bearing assembly 14 is secured to an upper plate on the post 1. A roll pin 16 extends through a cross-bore of the leadscrew 13 with end extension into a mechanism 17 thus connected with the leadscrew 13 for leadscrew locking/unlocking purposes, i.e. against rotation or free to rotate.

The post 1 is prevented from being removed by flange plate 18 secured to collar 19 fixed to the tube 2. Turning to Figure 2 for more detail of post locking/ retaining means, flange plates 22 and 23 are fixed to the tube 21, and accurately profiled plates, 24, 25 and 26 form a collar around the post 20 to co-act with stops/guides 27 fixed to the post 20. The collar is securely fastened to plates 23 and 24 by security fasteners 28-31. The plates 24, 25 and 26 are securely fastened together by other security fasteners 32, and are profiled to contain a specially profiled locking ring 33 shown in the medial plate 25. The locking ring 33 can be made from flat plate and has four apertures 34 to allow passage of security fasteners 28, 29, 30 and 31, a further aperture 35 accurately profiled to just allow a lock 36 to pass through, and a further smaller aperture 37 to allow a bar to be inserted in order to rotate the ring 33. For Figure 2A, the lock 36 has been removed and the locking ring 33 rotated so as to align apertures 34 with the security fasteners 28-31. Using an appropriate tool, these fasteners 28-31 can then be removed and the collar 24-26 removed so as to allow removal of the post 20. To secure the post 20, the collar 24-26 is replaced and the security fasteners 28-31 inserted, using the appropriate tool, the locking ring 33 is rotated such that the aperture 35 aligns with aperturing in the collar for the lock 36, and the lock 36 inserted. The locking ring 33 cannot then be rotated again until the lock 36 is removed typically needing an appropriate key.

When the locking ring 33 is in the locked position, apertures 34 no longer align with the fasteners 28-31, no tool can be inserted to remove the fasteners. As access to the fasteners 28-31 relies upon being able to rotate the locking ring 33, and it is difficult to gain any significant leverage to rotate the ring 33, very substantial security of locking/retention of the post 20 is afforded. This has several advantages over known removal means which traditionally comprise either immovably fixing a collar, for example, welding; or securing the collar with exposed security fasteners, the tools for which are readily available and therefore lessen the security actually afforded. The proposed locking means hereof does, however, allow full maintenance and servicing of the bollard, with high security maintained by the requirement for a key and covering of the fasteners 28-31.

Electronic control circuitry can be housed within the assembly, say at 2A (or in a separate dedicated housing) , and controls and sequences the automatic phase of operation. Starting with the post (1, 20) in the extended position, once a valid signal has been received, typically from a remote control, power is applied to the motor 11 in the correct polarity to lower the post (1, 20) until end of travel is reached when the post (1, 20) comes into contact with the bottom of the tube or sleeve (2, 21) causing the drive motor (11) to stall. Substantial increase in electric current drawn by the motor (11) at stall is readily sensed by the control circuitry in order to discontinue drive current to the motor. Sensing end of travel in this way eliminates the need for sensors such as micro-switches or photo-cells, any of which would be prone to unreliability in the harsh road-level operating environment. This current sensing process can also provide a safety over-ride in the event that the post, usually in extension, comes into contact with an obstruction before it reaches the normal end of travel .

Upon detection of end of travel, power is removed and, once a vehicle has passed over, a control signal sent from an appropriate sensing device or from the remote control to cause power to be re-applied to the motor in the correct polarity to reverse the motor drive shaft and thus raise the post to its upstanding extended position also detectable as to end of travel by driver motor stall current being detected.

In alternative embodiments, of course, electronic timers, micro-switches and/or tilt switches may be used to identify that the post has reached end of travel . Power for all operations of the post can be obtained from a standard re-chargeable battery which can also be contained within the assembly, say at 2A, or in a separate housing. Current drain from such battery is typically as standby power to receiver such as radio type, and as drive to the motor and control circuitry. Although the latter represents a heavy load, it is only required in short occasional bursts, and the greater drain on the battery over its operating life is usually the standby call. This drain can be minimised by duty cycle control for the receiver so as to be on for only short periods to monitor for an appropriate demand signal and to be switched off in between. This technique allows power savings of typically one or two hundred times with little perceivable effect to the user, and battery life of two or three years can be obtained from a suitable battery.

Alternative power supply arrangements include photocells at least for continuous standby power for the receiver, also substantially extending battery life. If photocells are used in conjunction with re-chargeable batteries, then battery replacement can be at very long intervals, even virtually eliminated. Another alternative is a mains derived supply which will eliminate the need for batteries as a primary source, batteries only being required then as back-up in the event of a mains power failure.

A hand operated wireless remote control is envisaged for the user. Operation of a button on the control transmits a signal, say of radio type in one of the licence-exempt bands reserved for such applications. Each traffic control bollard can be provided with its own unique code to prevent spurious operation of any neighbouring units .

In the event that the illustrated raising and lowering mechanism fails to operate for any reason, it is readily provided for the user to lower the post manually if in the upright position or raise the post manually if in the lowered position. This requires no more than controlled access to manual operation of the latch 17, say needing a special tool or key.

It should also be apparent to those skilled in the art that remote control means can be other than a radio frequency link, whether some other electro-magnetic radiation by other radiative means including acoustic or magnetic systems.

Figure 4 shows application of a non-self-sustaining leadscrew drive mechanism hereof 39, generally as described above but applied to a swinging arm barrier, specifically acting between ground and normally counter-weighted short extension of the arm past its medial pivotting shown joggled within a casing. Figures 5A, B likewise show application to a pivotting wedge to be raised from and returned to ground level by non-self-sustaining leadscrew mechanism 39 shown acting between in-ground accomodation pit and the hollow wedge itself.

The control circuitry of Figure 6 is based on a programmable microprocessor 40, e.g. that available commercially as PIC16C71. The microprocessor 40 is programmed to operate the drive and lock motors in response to a trigger signal and also according to motor current drawn.

The trigger signal is applied at trigger connection 41. The microprocessor 40 responds by producing control signals to operate the drive and lock motors via interlock circuitry 42 comprising a number of logic gates arranged to ensure that only appropriate signals are applied to the motors, including preventing a motor being driven in two directions simultaneously. Logic gate outputs from the interlock circuitry 42 are applied to a voltage level shifter 43 (e.g. device type 4504) so that motor drive signal voltages are appropriate to run the motors . Outputs from the level shifter 43 are fed to the motors via diodes 44 serving to protect the control circuit from any back emf. The drive motor is connected to terminals 45, 46; and the lock motor is connected to terminal 47. The current drawn by the motors is monitored by the potential divider 48 and amplifier 49 whose output to the microprocessor 40 is a signal corresponding to the current supplied to the motors.

The control circuitry also provides a number of other functions. Diodes 50 and resistors 51 provide a battery level monitoring and a signal indicates the electrical condition of the batteries to the microprocessor 40. Light emitting diode 54 enable a visual signal to be produced, say to indicate battery condition. Speaker 52 and circuitry 53 enable an audible warning signal to be generated, typically to indicate that the bollard post is moving. Voltage regulator circuitry 55 serves to supply a stable power supply; and circuitry including crystal 56 provides a clock signal for the microprocessor 40.

The trigger signal (41) can be provided by a conventional receiver, not illustrated, adapted to produce a signal, say of radio (rf) or infra-red or ultrasonic or other nature, in response to output of an associated conventional transmitter.

The microprocessor is readily programmed for at least the above functions. For example, when the post is in the upstanding locked position, a trigger signal 41 causes the microprocessor 40 to operate the drive motor to move the post to the lowered position. When the post reaches its limit of travel, the increase in the current drawn by the drive motor results in the microprocessor ceasing to supply power to the drive motor. Upon receipt of a further trigger signal at 41, the drive motor will be operated to raise the post to the upstanding position.

By comparing the time taken before the drive motor stalls with the expected time taken to raise or lower the post the microprocessor can readily distinguish between the post making contact with an end stop or an unexpected obstruction.

Although design and automatic operation of a bollard have been described above with specific reference to a battery-powered version, embodiments of the invention can readily be implemented in other versions. Indeed, any remotely-controlled movable item can be driven by a suitably adapted mechanism hereof, including whether or not for controlling access by vehicles or by individuals, i.e. personnel, animals or any moving object. Embodiments of the invention are particularly suited to temporary installation, perhaps especially in self-contained and self-powered form as described and illustrated.

Claims

1. Raisable and lowerable access control device comprising a drive mechanism that is usually powered from a local source of power to raise or lower an operative access obstructing component of the device, the drive mechanism being such that mechanical engagement between its operative parts does not obstruct unpowered movement of the component if one of its said operative parts is released, and locking means releasibly operative relative to said one operative part.

2. Device according to claim 1, wherein the operative component is a swinging arm with the drive mechanism at one side of pivotting of the arm.

3. Device according to claim 1, wherein the operative component is a pivotting wedge to rise from and return to ground level with the drive mechanism within the wedge in ground accommodation for the wedge.

4. Device according to claim 1, wherein the operative component is a bollard post with the drive mechanism within the post and/or in-ground tube or sleeve accommodation for the post.

5. An extensible and retractable bollard device comprising a tube or sleeve to be located in the ground with its upper end open substantially at ground level, a post slidable within the tube from a lower position at least substantially enclosed within the tube or sleeve, locking means to secure the post at least said in upper position, and a drive mechanism within the tube or sleeve to move the post relative to the tube or sleeve when powered, the drive mechanism being such that mechanical engagement between its operative parts does not obstruct unpowered movement of the post if one of its said operative parts is released, and the locking means being releasably operative relative to said one operative part.

6. Bollard according to claim 5, further comprising means to prevent the post from being removed other than by authorised personnel .

7. Device according to any preceding claim, wherein the drive mechanism is of a leadscrew nature that is not self- sustaining.

8. Device according to claim 7, wherein the locking means is operative or not relative to rotation of the leadscrew.

9. Device according to claim 7 or claim 8, comprising co- acting leadscrew nut rotation means that locks the nut when not driven .

10. Device according to claim 7, 8 or 9, wherein the leadscrew has flank (a) and lead (λ) angles trigonom- etrically related by the product of their respective cosine and tangent being not less than the coefficient of friction (μ) , i.e. μ < Cosc-Tanλ .

11. Device according to claim 10, wherein the lead angle is Tan^"1 (Lead/ττd₂) where lead is product of number of thread starts and thread pitch and d₂ is the basic pitch diameter.

12. Device according to any one of claims 7 to 11, wherein a drive mechanism body houses leadscrew nut rotating means.

13. Device according to claim 12, wherein the leadscrew nut rotating means comprises a worm gear co-acting with an edge gear form of the nut .

14. Device according to claim 13, wherein driven for the worm gear is by way of and associated fix and spur gear and reduction gearing from an electric motor drive pinion.

15. Device according to claim 14, comprising electronic motor control means including sensing of the drive mechanism reaching desired extension and retraction.

16. Device according to claim 15, wherein said sensing is according to motor drive current changes at reaching mechanical limits of drive movement.

17. Device according to claim 16, wherein said limits are defined by resilient stops.

18. Device according to claim 15, 16 or 17, wherein the control means applies said sensing to detecting encountering of any obstruction.

19. Device according to claim 18, wherein the control means is operative at sensing said obstruction to apply predetermined reversal of motor drive .

20. Device according to any one of claims 15 to 19, including signal receiving means to which the control means is responsive.

21. Device according to claim 20, wherein the control means is enabled only when the signal receiving means receives a coded signal.

22. Device according to claim 21, wherein the control means has a minimum power consumption mode except when enabled.

23. Device according to claim 20, 21 or 22, wherein the control means is operative to enable the receiving means only briefly at predetermined intervals of time.

24. Device according to any one of claims 14 to 23, further comprising an electric battery for all power requirements .

25. Bollard device according to any one of claims 4 to 24, wherein the post has biassing away from said lower position.

26. Bollard device according to claim 25, wherein the biassing is by a compression spring acting between the post and the tube or sleeve.

27. Bollard device according to claim 25 or 26, wherein the biassing is substantially equal and opposite to gravity acting on the post.