[0001] The present invention relates to a device of the type embodying a gate with a bar
raised and lowered by means of servomechanisms, e.g. to regulate the transit of vehicles
for obligatory passages, e.g. access to parking lots, warehouses, etc.
[0002] In the known art there are often used hydraulic systems to provide servomechanisms.
One solution adopted is to use a hydraulic actuator with a double-action piston to
control the movements of raising and lowering of the bar. Unfortunately one considerable
shortcoming of said solution is the complexity of the hydraulic system necessary to
control said double-action actuators and their relatively high cost.
[0003] Another problem of the known art is that the force necessary to raise the bar is
obviously different from that necessary to lower it and therefor for reasons of economy
the servomechanisms employed to perform the two different operations are of different
sizes. This requires that to raise the bar with clockwise or counter-clockwise rotation
there are necessary two different bar gate devices of different design or it is necessary
to provide a gate device with a shaft for rotation of the bar which allows fixing
of the bar to one end or the other thereof. The first solution has the shortcoming
of cost while the second has the shortcoming that the ends of the shaft must both
project from the body of the device to allow fixing of the bar at one or the other
of them with obvious problems of an aesthetic nature and the need to provide special
covers for the unused end.
[0004] The general object of the present invention is to overcome the above mentioned shortcomings
by providing a bar gate device without costly double-action actuators and which would
allow installation both of clockwise opening bars and counter clockwise opening bars
on the same end of the control shaft.
[0005] In view of said object there is provided in accordance with the invention a controlled
gate device comprising a bar moving between a horizontal position to block a passage
and a vertical position to free said passage by means of servomechanisms acting to
rotate a horizontal shaft supporting the bar near one of its ends and characterized
in that said servomechanisms comprise a lever with equal arms and its fulcrum pivoted
on said shaft and two equal single-action hydraulic actuators each connected between
a corresponding end of the lever and the structure supporting the device fixed to
the ground, to control operation, a first actuator the movement of reaching the vertical
position and the other actuator the return to the horizontal position of the bar,
there being connected to said lever means of reaction in the direction necessary to
counterbalance the moment produced by the weight of the bar on the shaft balancing
the forces of operation of the hydraulic actuators, the whole consisting of a lever
and actuators being symmetrical in relation to the vertical plan passing through the
shaft.
[0006] To clarify the explanation of the innovative principles of the present invention
and its advantages compared with the known art there is described below a possible
embodiment as an example of application of said principles. In the drawings:
FIG. 1 shows a partial cross section view along plane of cut I-I of FIG. 2 of a rear
elevation of a bar gate device provided in accordance with the present invention,
and
FIG. 2 shows a partial cross section view of a side elevation along plane of cut II-II
of FIG. 1.
[0007] With reference to the figures a bar gate device (indicated generally in the figures
by reference number 10) in accordance with the invention comprises a box 11 fixed
to the ground and containing two single-action hydraulic actuators 12 and 13 with
the ends of the cylinders connected by pivot to brackets (14, 15) to support respectively
the box and the ends of the rods connected to pivots at the ends of a two-armed lever
16 pivoted on a shaft 17 supported in a rotating manner by means of bearings 18, 19
by a frame 20 fixed to the box 11.
[0008] The shaft 17 bears at one end projecting from the box a bar 21 partially shown.
[0009] The actuator 13 bears coaxially a thrust spring 22 reacting between the cylinder
and the rod by means of spring stops 23, 24 respectively and acting by compensation
of the moment produced by the weight of the bar 21 on the shaft 17 in such a manner
that the two actuators 12 and 13 can be identical since they have to develop a virtually
equal force. For this purpose the spring 22 must be selected with allowance for the
weight and length of the bar 21.
[0010] The actuators are controlled alternately through flexible ducts 25 and 26 by a control
circuit indicated generally by reference number 27 and not further represented nor
described since it is an electrohydraulic circuit of the known art and hence easy
to imagine by those skilled in the art.
[0011] As may be seen in the drawings the mechanism consisting of the actuators 12 and 13
and the linkage 16 is perfectly symmetrical except for the presence of the spring
22 in relation to the vertical plane containing the shaft 17. In this manner the device
10 can be used to advantage to operate a closing bar 21 lowering clockwise or counter-clockwise
merely by moving the spring 22 and the spring stop element 24 from one actuator to
the other and rotating the position of the bar on the shaft by 90°.
[0012] Indeed, with the spring positioned as shown in the figures and fitted on the actuator
13 and the bar vertical when the actuator 12 is retracted the device closes the passage
in a clockwise manner (passage to the right of the device 10) in accordance with the
orientation shown in FIG. 1. With the spring fitted on the actuator 12 and the bar
fixed to the shaft 17 in vertical position when the actuator 13 is retracted there
is provided a counter-clockwise closing device (passage to the left of the device
10) in accordance with the orientation shown in FIG. 1.
1. Controlled gate device comprising a bar moving between a horizontal position to
block a passage and a vertical position to free said passage by means of servomechanisms
acting to rotate a horizontal shaft supporting the bar near one of its ends and characterized
in that said servomechanisms comprise a lever with equal arms and its fulcrum pivoted
on said shaft and two equal single-action hydraulic actuators each connected between
a corresponding end of the lever and the structure supporting the device fixed to
the ground, to control operation, a first actuator the movement of reaching the vertical
position and the other actuator the return to the horizontal position of the bar,
there being connected to said lever means of reaction in the direction necessary to
counterbalance the moment produced by the weight of the bar on the shaft balancing
the forces of operation of the hydraulic actuators, the whole consisting of lever
and actuators being symmetrical in relation to the vertical plane passing through
the shaft.
2. Device in accordance with claim 1 characterized in that the means of reaction comprise
a thrust spring fitted coaxially over the actuator controlling the movement of the
bar to the vertical position and reacting between cylinder and rod of said actuator.
