AU2009200999A1 - Sliding Gate Limit Sensing - Google Patents

Description

-2 SLIDING GATE LIMIT SENSING Field of the Invention 5 This invention relates to sliding gate limit sensing and relates particularly although not exclusively to sliding gate sensing for gates of driveways. Background Art 10 Hitherto, it has been known to provide sliding gate operators to cause a sliding gate to open and close across a driveway. Typically, such sliding gate operators include an electric drive motor which drives a pinion 15 wheel. The gate carries an elongate rack and the pinion gear engages with the rack. Accordingly, rotation of the pinion wheel causes the sliding gate to extend or retreat which, in turn, closes or opens the sliding gate relative to a gateway across a driveway. Typically, the sliding 20 gate operator can be remotely radio controlled to facilitate easy user operability. Sliding gate operators are sometimes used for opening and closing doors or other similar panel like 25 arrangements. Thus, the term "sliding gate" as used herein is to embrace not only sliding gates but any other equivalent such as sliding doors or panels. Known sliding gate operators include an assembly that 30 has a limit switch sensing mechanism which co-operates with the sliding gate to switch off drive to the electric drive motor when the sliding gate reaches end positions of travel. Typically, the electric drive motor is mounted in a housing which forms a casing of the sliding gate 35 operator. The limit switch sensing means typically comprises a pair of micro switches, where one is used to control an open position of the gate, and the other is N \Melboume\Cases\Patent\77000-77999\P77273,AU\Specis\P77273.AU Specification - CAP 2008-3-25.doc 12103/09 -3 used to control a closed position of the gate. Accordingly, when the gate reaches the open and/or closed positions, a respective micro switch is activated to effect switching off of power to the electric drive motor 5 to, in turn, stop drive of the sliding gate. Typically, the micro switches are mounted on respective sides of a flexible arm that engages with the gate at the end positions of travel. The flexible arm protrudes from the sliding gate operator into the path of stops that are io provided on the sliding gate. Accordingly, as the gate is opened and/or closed, the stops engage with a left hand side or a right hand side of the flexible arm. As the sliding gate continues to travel, the flexible arm flexes which, in turn, presses against a respective one of the is micro switches. The aforementioned limit switch sensing is unreliable for the setting of accurate stop positions. In addition, sometimes the flexible arm jambs against the stops and/or the sliding gate and requires user intervention to free the arm for future intended 20 operation. There is a need for improved limit sensing. Statement of the Invention 25 Therefore, according to a first aspect of the present invention there is provided a sliding gate operator limit switch assembly for stopping drive of a sliding gate driven by a sliding gate operator when the sliding gate 30 reaches end positions of travel, said sliding gate carrying end position stops that will co-operate with limit switch means carried by said limit switch assembly and which will be activated to switch off electric power to an electric drive motor associated with said sliding 35 gate operator, said limit switch assembly having a body carrying limit switch means fixed thereto and a limit switch N:\Melboume\Cases\Patent\77000-77999\P77273.AU\Speis\77273.AU Specification - CAP 2008-3-25.doc 12/03/09 activator mounted to swing about an axis that extends generally perpendicular to a direction of sliding of said sliding gate, said activator being biased in the absence of an end 5 position stop to assume a neutral position where said limit switch means will not be activated to switch off power to the electric drive motor, said activator having an arm extending therefrom for engagement with the end position stops carried by said sliding gate, 10 and wherein, in use, when the arm is engaged by an end position stop, continued sliding movement of said sliding gate will cause the necessary co-operation with the limit switch means by swinging said actuator about said axis and to switch said limit switch means to switch 15 off power to drive said electric drive motor. In one embodiment, the limit switch means comprises a gate open limit switch and a gate closed limit switch, and wherein the two limit switches are carried on said body so 20 said axis is therebetween, so that swinging of said actuator in a clockwise direction about said axis causes operation of one of the limit switches to switch off power to said electric drive motor and swinging in an anticlockwise direction causes operation of the second of 25 the limit switches to switch off power to said electric drive motor. In one example, said biasing to said neutral position is effected by spring means extending from said housing to 30 said actuator. In one example, said actuator and said arm have a generally "T" shape and wherein said axis is at the junction of the head of the "T" with the trunk of the "T" 35 and mutually perpendicular thereto. In one example, the limit switch means is a mechanically operable micro switch means. N:\elboume\Cases\Patent\77000-77999\P77273.AU\Specis\P77273.AU Specification - CAP 2000-3-25.doc 12/03/09 -5 Brief Description of Drawings In order that the invention can be more clearly ascertained an example of the invention for use with a 5 sliding gate to close a driveway will now be described wherein: Figure 1 is an elevational schematic view showing basic conceptual components, 10 Figure 2 is a plan view of the arrangement shown in Figure 1, Figure 3 is an enlarged view of a sliding gate shown 15 in Figures 1 and 2 with certain other components added, Figure 4 is an end view showing an end of the sliding gate and the positioning of a sliding gate operator, 20 Figure 5 is a plan view of the arrangement shown in Figure 3, Figure 6 is an exploded perspective view of a component of an example of a limit switch assembly, 25 Figure 7 is a plan view showing operation of the limit switch assembly of Figure 5 at one end position of the sliding gate, 30 Figure 8 is a view similar to that shown in Figure 7 at the opposite end position, Figure 9 is a side elevation of the limit switch assembly, and 35 Figure 10 is a front elevational view of the limit switch assembly. N:\Melboume\Cases\Patent\77000-77999\P77273.AU\Specis\P77273.AU Specification - CAP 2008-3-25.doc 12103/09 -6 Detailed Description of Examples Referring firstly to Figure 1, there is shown a sliding gate installation where a sliding gate 1 closes a 5 driveway 3 defined by two fences or walls 5. The sliding gate 1 has been shown schematically with an outer peripheral frame 7. The outer peripheral frame 7 may be filled-in any convenient way by either solid panel filling or by bars or mesh as is customary. The sliding gate 1 is 10 supported by two or more roller wheels 9 that travel in a track 11 (see Figure 4). The track 11 is shown in this example as an inverted "V" and is typically comprised of a length of a right angle steel or metal section embedded into a concrete driveway 13. The particular profile shape 15 of the track 11 varies between different installations and is not critical. In some cases, a track 11 is not provided. Figures 1 and 2 show that there is at least one, but 20 desirably more, upper supports 15 that hold the sliding gate 1 in an upright position. A sliding gate operator 17 is mounted at one side of the driveway opening 3 and contains an electric drive motor for driving the sliding gate 1 between open and close positions. Figure 3 shows 25 that a rack 19 is carried by the sliding gate 1. The rack 19 extends along the length of the sliding gate 1 at the bottom thereof. Figure 4 shows that the rack 19 is fastened at a side edge of the outer peripheral frame 7. This can be by bolts or screws or any other convenient 30 means. The rack 19 has teeth 21 that engage with corresponding teeth of a pinion gear 23 (Figures 3 and 4 best show this arrangement). The pinion gear 23 is, in turn, driven by an electric drive motor (not shown) within the housing of the sliding gate operator 17. Accordingly, 35 a clockwise drive of the pinion gear 23 causes the sliding gate 1 to advance in one direction and an anticlockwise direction of rotation of the pinion gear 23 causes the N:\elboume\Cases\Patent\77000-779\77273.AU\Specis\77273.AU Specification - CAP 2008-3-25.doc 12103/09 -7 sliding gate to retreat in the opposite direction. Figure 3 shows end position stops 25 positioned respectively at each of the ends of the rack 19. These end position stops 25 define the stop position for the sliding gate 1 at the 5 door open and door closed positions. The end position stops 25 can be adjusted to a position along the length of the rack 19 to provide some degree of adjustment for the end stop positions. Typically, the end position stops 25 have elongate slots therein and bolts pass through the 10 elongate slots into the upper surface of the rack 19. The bolts can be loosened and the end position stops 25 slid along the rack to the limits provided by the length of the elongate slots. The bolts can then be tightened at desired end stop positions. 15 The above described arrangement is prior art. Figures 5 - 10 show an example of a limit switch assembly in accordance with the present invention. Here, 20 the limit switch assembly 27 has a body 29 made from a suitable material such as industrial grade plastics. The body 29 has a somewhat "C" shape in side elevation to provide an upper part 31 and a lower part 33 extending from a interconnecting trunk part 35. The trunk part 35 25 has two recesses 37 of a suitable size to receive respective switch means 39. The upper part 31 and the lower part 33 have aligned bore openings 41 for receipt of an axle 43. The axle 43, in turn, swingably supports an actuator 45 for rotation about a central longitudinal axis 30 of the axle 43. An arm 47 extends from the actuator 45 so that the actuator and the arm together have a generally "T" shape in plan view. The arm 47 carries a head 49 that will engage with a respective end position stop 25. This will be explained further hereinafter. The switch means 35 39 are assembled into the body 29 in the respective recesses 37. In this example, the switch means 39 comprises mechanically operable micro switches. N:\Melboumo\Cases\Patent\77000-77999\P77273.AU\Speris\P77273.AU Specification - CAP 2008-3-25.doc 12/03/09 -8 Accordingly, the switch means 39 is shown with activation buttons 51. Other type of switch means 39 may be activated in a different way. For example, switch means 39 may comprise proximity sensing switch means. 5 The actuator 45 is mounted and carried by the axle 43 which is suspended, in this case, in an upright manner by locating with the respective bore openings 41. The actuator 45 may swing relative to the axle 43 or 10 alternatively the actuator 45 may be rigidly attached relative to the axle 43 so that the axle 43, in turn, swings relative to the bore openings 41. The effect of the arrangement is to allow the actuator 45 to swing about the central longitudinal axis of axle 43. It can also be 15 seen that the central longitudinal axis of the axle 43 is mutually perpendicular to the actuator 45 and the central longitudinal axis of the arm. In the examples shown, the actuator 45 and the arm 47 have a generally "T" shape in plan view and the central longitudinal axis is at the 20 junction of the head of the "T" with the trunk of the "T", and mutually perpendicular thereto. In other words, the actuator 45 is shown to be generally planar in configuration. In other examples, the actuator 45 and the arm 47 may be made integrally with each other. 25 When the arm 47 is engaged with an end position stop 25 as shown in Figures 7 and 8, and there is continued movement of the sliding gate 1, the actuator 45 will be caused to swing clockwise or anticlockwise. Figures 7 and 30 8 show that the respective switch means 39 are engaged by the actuator 45 at these respective end positions so there can be switching off of power to the electric drive motor in the sliding gate operator 17. 35 Figure 6, in particular, shows biasing means 55 in the form of compression springs that locate in bores 57 in the trunk part 35 of the body 29 directly underneath the N:\Melboume\Cases\Patent\77000-77999\77273.AU\Specis\P77273.AU Specificaton - CAP 2008-3-25.doc 1210309 -9 recesses 37. The biasing means 55 therefore extend from the body to the actuator 45 and bias the actuator to a neutral position so that neither of the switch means 39 is normally acting to switch off power to the electric drive 5 motor. In the arrangement shown, the biasing means 55 actually engages with the actuator 45. However, in some other examples, the biasing means 55 may not physically directly engage with the actuator 45 but only engage with the actuator 45 after there is an initial movement caused 10 by the passing of the end position stops 25. Figure 6 also shows a further alternative, or additional biasing means 59 in the form of a coil spring that is passed over the upper end of the axle 43 to engage with the axle and with a part of the upper part 31 of the body 29. 15 Accordingly, the biasing means 59 will act like a torsion spring to cause the axle and actuator 45 to assume a neutral position where the actuator 45 is not operating a respective switch means 39 to switch off power to the electric drive motor. Preferably the biasing means 55 and 20 59 comprise stainless steel springs. Other forms of biasing means are not excluded. The arm 47 may typically be flexible and semi rigid and may be formed from a tightly wound spring like metal 25 material. By providing the arm 47 of a flexible but semi rigid material, there can be assured correct swinging operation of the actuator 45, however, if there should be some failure in the system and the sliding gate 1 moved to a position where the end position stops 25 are causing the 30 actuator 45 to press firmly against actuation buttons 51 of the switch means 39, then the arm 47 will flex without causing damage to the limit switch assembly 27. The arrangement described above provides for a 35 superior limit switch sensing in sliding gate operator mechanisms than known in the past. In this arrangement, it can be seen that the arm 47 does not directly engage N:\Melboume\Cases\Patent\77000-77999\P77273.AU\Specis\P77273.AU Specification - CAP 2008-3-25.doc 12/03109 - 10 the actuation buttons 51, as is the case with known prior art limit switch assemblies. In such known prior art, the arm 47 strikes one of the actuation buttons at one end position and then swings to strike the opposite actuation 5 button 51 at the other of the end positions. With the example described above, good accuracy control for setting of end stop positions can be realised. Moreover, once set, the sliding gate 1 can continually and 10 reliably be expected to stop at the set positions. Modifications may be made to the invention as would be apparent to persons skilled in the art of producing limit switch sensing for sliding gates. For example, the 15 actuator 45 may be manufactured from metal or from any suitable industrial grade plastics. The axle 43 and the bore openings 41 may be suitably journalled with appropriate bearings to ensure accuracy of operation. The arm 47 may be made of a flexible resilient plastics 20 material. Alternatively, it may be made from a tightly wound metal material such as spring steel. Further, it is known for micro switches to have a spring loaded actuator button or lever. The spring of 25 such button or lever may be used to bias the actuator to the neutral position thereby obviating the need for the biasing means 55 or 59. This of course does not mean that in this arrangement, that the biasing means 55 or 59 can be dispensed with as it may be desirable to include these 30 biasing means 55, 59 to supplement the biasing provided by the button or lever. It is to be understood that, if any prior art publication is referred to herein, such reference does not 35 constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. N:Melboume\Cases\Patent\770O0-77999\P77273.AU\Specis\P77273.AU Specification - CAP 2008-3-25.doc 12/03/09 - 11 In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word 5 "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 10 These and other modifications may be made without departing from the ambit of the invention the nature of which is to be determined from the foregoing description. 15 N:\elboume\Cases\Patent\77000-77999\P77273.AU\Specis\P77273.AU Specification - CAP 2008-3-25.doc 12/03/M9

Claims (5)

1. A sliding gate operator limit switch assembly for stopping drive of a sliding gate driven by a sliding gate 5 operator when the sliding gate reaches end positions of travel, said sliding gate carrying end position stops that will co-operate with limit switch means carried by said limit switch assembly and which will be activated to switch off electric power to an electric drive motor 10 associated with said sliding gate operator, said limit switch assembly having a body carrying limit switch means fixed thereto and a limit switch activator mounted to swing about an axis that extends generally perpendicular to a direction of sliding of said 15 sliding gate, said activator being biased in the absence of an end position stop to assume a neutral position where said limit switch means will not be activated to switch off power to the electric drive motor, said activator having 20 an arm extending therefrom for engagement with the end position stops carried by said sliding gate, and wherein, in use, when the arm is engaged by an end position stop, continued sliding movement of said sliding gate will cause the necessary co-operation with 25 the limit switch means by swinging said actuator about said axis and to switch said limit switch means to switch off power to drive said electric drive motor.

2. An assembly as claimed in claim 1, wherein said limit 30 switch means comprises a gate open limit switch and a gate closed limit switch, and wherein the two limit switches are carried on said body so the axis is therebetween, so that swinging of said activator in a clockwise direction about said axis causes operation of one of the limit 35 switches to switch off power to said electric drive motor and swinging in an anticlockwise direction causes operation of a second of the limit switches to switch off N:\Melboume\Cases\Patent\77000-77999P77273.AU\Specis\P77273.AU Speciflcation - CAP 2008-3-25.doc 12/0309 - 13 power to said electric drive motor.

3. An assembly as claimed in claim 2, wherein said biasing to said neutral position is effected by spring 5 means extending from said body to said actuator.

4. An assembly as claimed in claim 3, wherein said actuator and said arm have a generally "T" shape and wherein the axis is at the junction of the head of the "T" 10 with the trunk of the "T" and mutually perpendicular thereto.

5. An assembly as claimed in any one of the preceding claims, wherein said limit switch means is mechanically 15 operable micro switch means. N:\Melboume\Cases\Patent\77000-77999\P77273.AU\Specis\P77273.AU Specdcation - CAP 2008-3-25.doc 12103/09