GB2294972A

GB2294972A - Operating mechanism for a barrier

Info

Publication number: GB2294972A
Application number: GB9522716A
Authority: GB
Inventors: Arthur Arnold
Original assignee: APT Controls Ltd
Current assignee: APT Controls Ltd
Priority date: 1994-11-09
Filing date: 1995-11-06
Publication date: 1996-05-15
Anticipated expiration: 2015-11-06
Also published as: GB9522716D0; GB9422574D0; GB2294972B

Abstract

An operating mechanism for a barrier 14 having a driven rotatable shaft 13 has a reversible drive motor 12 connected to the shaft 13 by means of a Geneva mechanism 16, 20. The barrier may be for example a pole 14, a gate or a turnstile. <IMAGE>

Description

OPERATING MECHANISM FOR A BARRIER The present invention relates to a mechanism for operating a barrier.

Many different mechanisms have been proposed for raising and lowering barrier poles about a fixed horizontal pivot or for opening a gate or turnstile about a fixed vertical pivot. Such known mechanisms include hydraulic or pneumatic cylinders adapted to operate a lever connected to a rotatable shaft of the barrier, and rotatable screws and followers again attached to a lever or other mechanism connected to the rotatable shaft. Notwithstanding the capabilities of such known mechanisms, there is a demand for improved devices which will open and close a barrier such as a pole or a gate or a turnstile more rapidly, but safely. Such a device must be simple and robust in order to be inexpensive in manufacture and substantially maintenance-free.

According to the present invention there is provided an operating mechanism for a barrier having a driven rotatable shaft, the mechanism comprising a reversible drive motor connected to the shaft by means of a Geneva mechanism.

A Geneva mechanism is a device which ensures positive motion control commensurate with fast action and including acceleration and deceleration properties at the commencement and termination respectively of the motion effected.

An embodiment of the invention will now be described with reference to the accompanying drawing in which Fig. 1 is a side elevation of an operating mechanism for a barrier pole which, in use, is to be moved between a horizontal position in which it provides a barrier, for example, to prevent vehicular access, to a vertical position to permit access when required.

The mechanism includes a base plate 10 supporting a vertical column 11 to the lower region of which is attached a 24-volt electric motor 12. The column 11 carries near its upper end a rotatable shaft 13 which is to be driven in rotation through 900 to permit movement of a barrier pole 14 from its illustrated horizontal position to a vertical position as indicated by arrow 15. Rigidly attached to the shaft 13 for rotation therewith is a slotted member 16 forming part of a Geneva mechanism. The slotted member 16 includes a slot 17 for receiving a pin 18 attached to a radial arm 19 of an angular member 20 which forms another part of the Geneva mechanism.

The angular member 20 is rotatably engaged upon a shaft 21. The shaft 21 engages a belt pulley 22 around which is wrapped a drive belt 23.. The drive belt 23 is also wrapped around a smaller pulley 24 which is mounted on a second rotatable shaft 25 which is the output shaft of a gearbox 26. The input of the gearbox 26 is connected to the drive motor 12. Bearings on the column 11 are provided for the shafts 13, 21.

The slotted member 16 of the Geneva mechanism includes a pair of lateral wings 27, 28, the outer ends 27A, 28A of which contact one or other of a pair of switches 29 at the limits of movement of the slotted member 16. The slotted member 16 and the angular member 20 of the Geneva mechanism each have two respective curved faces 30, 31, a respective pair of which are shown engaged at 32, whereby the mechanism is locked against rotation at both operational ends of the permitted movement of the mechanism.

In operation, in the condition illustrated in Fig. 1, the barrier pole 14 is locked in its horizontal, lowered position by a first pair of abutting faces 30, 31 of the slotted member 16 and the angular member 20 of the Geneva mechanism. To raise the pole 14, a switch (not shown) such as a sensor cable in the road surface is actuated to energise motor the 12 to commence rotation of the two pulleys 24, 22 in an anti-clockwise direction.

Accordingly, the radial arm 19 is rotated anti-clockwise, causing the pin 18 to enter the slot 17 in the slotted member 16 Continued anti-clockwise rotation will cause the abutting curved faces 30, 31 of the slotted member 16 and angular member 20 to disengage and the movement of the pin 18 in the slot 17 produces a rapid clockwise motion of the slotted member 16 and shaft 13, the pin 18 accelerating towards the top of the slot 17 and then decelerating towards a limit of the clockwise rotation of the angular member 16. At the limit of movement, the barrier 14 assumes a vertical position and the end 27A of the wing 27 of the slotted member 16 contacts the switch 29 on the left hand side of the column 11 as viewed in the Fig. 1. This switches off the motor 12 and thus the entire mechanism.

In this condition, the slotted member 16 and the angular member 20 are interengaged in a manner similar to that illustrated but with the slotted member 16 rotated clockwise through 900 and the angular member 20 having been rotated anti-clockwise through 900, with the other respective pair of curved faces 30, 31 abutting each other to lock the barrier 14 in a vertical orientation.

Similarly, when the barrier 14 is to be lowered, the motor 12 is energised in the reverse direction to rotate the angular member 20 clockwise and the slotted member 16 anti-clockwise. At the limit of movement, the end 28A of the wing 28 contacts the right-hand switch 29 to stop the motor 12.

A torque limiter may be placed on the shaft 21 so that if the barrier 14 should strike an object during its pivoting movement, the torque limiter will prevent continued motion.

Electrical or electronic control means may be provided to reverse the motor 12 immediately in order to raise the barrier 14 to its vertical position if the barrier 14 strikes an object as it descends.

If required, the weight of the pole 14 may be counterbalanced by attaching a tension spring to the slotted member 16 in the region of the outer end 28A of the wing 28 and to a fixed position on the base plate 10.

It will be appreciated that the Geneva mechanism imparts a rapid motion to the barrier pole 14 but that this motion is decelerated as the pole 14 approaches its limit of movement as determined by the progression of pin 18 radially outwardly from the rotational axis of the slotted member 16 of the mechanism. Similarly, when the movement commences, the motor 12 is not under initial load until the pin 18 engages the slot 17 and moves towards the upper end thereof. The elimination of "whip" in the barrier pole 14 is highly desirable and is usually provided by a complex system of electronic or hydraulic/pneumatic control. The simple robust nature of the Geneva mechanism of the present invention ensures adequate acceleration and deceleration whilst providing rapid motion throughout a substantial part of the travel of the pole.

Since the motor 12 is protected by the interengagement of the slotted member 16 and angular member 20 as at 32, thus preventing any reverse drive by manual movement of the pole 14, it is possible to provide a low voltage motor 12, thus reducing the cost of manufacture and operation. The gearbox 26 is also protected by the locking characteristics of the Geneva mechanism.

Furthermore, the gearbox 26 is effectively decoupled from the barrier pole 14 in that a belt 23 provides the connection, compared to a fixed mechanical connection via gears or the like as in many prior art systems. This means that if the barrier pole 14 is forced upwards or downwards, the belt 23 will slip, thereby preventing transmission of otherwise destructive forces to the gearbox 26.

It will be appreciated that although the foregoing description relates to the operation of a horizontally pivoted barrier pole, the movement of which is through an arc located in a vertical plane, the operating mechanism may be applied to a vertically pivoted gate or turnstile wherein the shaft 13 may be attached to a vertical hinge pin. In the case of a gate or turnstile in which the movement is in a horizontal pane, the drive mechanism may be operated at a slower speed but still provides a low-load starting condition and a decelerated motion.

Other than the possible requirement for a less rapid movement of the gate or turnstile, it is envisaged that the overall mechanism will be generally similar to that described for the barrier pole above except that the final drive shaft 13 is positioned for rotation about a vertical axis. This may be provided by locating the entire mechanism on its side beneath the ground or by providing a 900 drive transmission to the hinge pin of the gate or turnstile.

The entire operating mechanism is provided with a cover 33 preferably of a flexible and thus substantially vandal-proof material, there being a key-operated lock 34 to secure the cover to the column 11. Also, a part of the cover 33 may be of a transparent material displaying, for example, a direction arrow, and a lamp may be mounted on the column 11 to illuminate the cover 33, thus making the entire mechanism visible at night.

Claims

1. An operating mechanism for a barrier having a driven rotatable shaft, the mechanism comprising a reversible drive motor connected to the shaft by means of a Geneva mechanism.

2. An operating mechanism according to claim 1, wherein the barrier is a pole.

3. An operating mechanism according to claim 1, wherein the barrier is a gate or turnstile.

4. An operating mechanism according to any of claims 1 to 3, wherein the Geneva mechanism includes a slotted member rotatable with the barrier shaft, and a rotatable angular member which is driven by the drive motor and which engages with the slotted member, the angular member carrying a pin for engagement with a slot in the slotted member to transmit drive from the angular member to the slotted member.

5. An operating mechanism according to claim 4, wherein the slotted member and the angular member have respective curved faces for engagement with each other to lock the barrier in position at the extremes of its movement.

6. An operating mechanism according to claim 4 or claim 5, wherein the angular member is connected to the drive motor by a belt.

7. An operating mechanism according to any of claims 1 to 6, further comprising at least one limit switch for switching off the motor at the limit of movement of the barrier.

8. An operating mechanism for a barrier, substantially as described with reference to the accompanying drawing.