TECHNICAL FIELD

The present invention is applicable in the field of electrical devices for industrial use and it particularly relates with a modular structure for safety switches for controlling access of industrial machines and plants applicable to movable protections such as barriers, shelters, inspection panels or the like.

STATE OF THE ART

Known switches for controlling access or barriers repair and/or safety perimeters for industrial machines or plants generally comprise a switching device anchored to the fixed part of the access and an actuator device anchored to the movable part.

Such switches have the aim of blocking the plant upon the opening of the access for obvious safety reasons, while activating one or more signaling or service circuits. Likewise, the switches can allow the machine or system to restart immediately after the access has been closed unless there is a condition requiring a specific operator intervention.

The control of the switching means for opening and closing the power supply circuit of the machine or plant can be carried out either by means of a mechanical or electronic actuator.

The first type switches, an example of which is disclosed in EP2112674 in the name of the same applicant, are usually provided with a key actuator associated with the movable device and adapted to be inserted into a slot of the switching device to interact with a driving mechanism of switching means for opening/closing the supply circuit and any auxiliary circuits.

The aforementioned patent also has a centering system consisting of a centering pin associated with the movable actuator device, also provided with a key actuator, and designed to fit into a centering hole provided in a special block mounted above the switching device.

The electronic operated switches instead provide that the two devices are provided with respective electronic circuits adapted to interact with each other by sending an identification signal by the circuit associated with the actuator device so as to cause the opening or closing of the main power circuit depending on their reciprocal distance. Examples of electronic actuator switches are described in WO2015083143 and WO2015083144, in the name of the same Applicant, which also comprises centering means for recover possible misalignment between the devices.

The switch also comprises an auxiliary module interposed between the casing housing the switching means designed to be connected to the power supply circuit of the machine or plant and a rotating head that houses the electronic communication circuit and which is also provided with a hole for inserting a centering pin associated with the actuator device.

The auxiliary module is associated with a control manually-operated by an operator to interact with the switching means and/or the driving means in emergency conditions or whenever necessary.

For example, the control may be designed to produce the opening of the switching means in emergency situations or to manually disengage the switch and allow access to the machine or plant.

A same switch may be designed to be coupled with different modules to be implemented with the most suitable control depending on the user's intended use and choices.

EP2362402, always in the name of the same Applicant, describes a switch having a casing housing the switching means and that is adapted to be selectively coupled to actuator modules that differ structurally in a sensitive manner according to their specific function.

This structural difference means that the different modules require a specific design of each part and do not have any degree of interchangeability.

Therefore, the realization of a series of auxiliary modules designed to be applied to the same switch requires the design and production of several components, resulting in increased production costs that are reflected in an increase in the final cost of the switch. A further drawbacks of the known solutions is that the fixing of the casing to the fixed part of the barrier can take place according to a single orientation as the fixing holes are present only on the front face and the rear face.

Therefore, in the case wherein the closing of the movable part does not occur in front of the casing, it is necessary to rotate the head by 90° to allow the interaction between both the centering means and the electronic circuits.

This configuration requires a relatively large number of components and involves a greater axial development of the switching device.

As a consequence, this solution, suitable for particularly complex installations, may be oversized and economically unsuitable for use with simpler machines or installations.

SCOPE OF THE INVENTION

The object of the present invention is to overcome the above drawbacks by providing a modular structure for safety switches for controlling access and/or protections for industrial machines and plants that has high efficiency and relative cost efficiency.

A particular object is to provide a modular structure for safety switches with an auxiliary control module wherein the design and production costs of the different control modules associated with a same switch are greatly reduced.

Yet another object is to provide a modular structure for safety switches requiring a relatively small number of elements for the realization of several control auxiliary modules different in their function.

Last but not least object is to provide a modular structure for safety switches that allows to obtain safety switches with a particularly simple and compact structure in order to reduce production and maintenance costs but at the same time maintain high flexibility in use, being adapted to be associated either with hinged access or sliding access, either of the right or left type.

A particular object is to provide such a modular structure for assembling safety switches that can be anchored to any type of opening without the use of external fixing means such as brackets or the like.

Yet another object is to provide a modular structure for safety switches wherein the drive system is completely electronic in order to guarantee the highest safety standards. Such objects, as well as others that will become more apparent hereinafter, are achieved by a modular structure for safety switches for controlling access of industrial machines and plants which, according to claim1, comprises a casing anchorable to a fixed part of the access to be controlled and housing thereinside switching means for controlling one or more control and/or service circuits of the machine or plant, driving means adapted to interact with said switching means at the opening/closing of the access for opening/closing one or more circuits, an auxiliary module adapted to be anchored to said casing and housing at least one manually operable control to operate on said switching means and/or said drive means.

The auxiliary module comprises a hollow box body having at least one opening for the insertion of said control, said opening being provided with first connection means for removable connection of said control.

The control is selected within a series of controls having different functions between them and each having a fixing rod which adapted to be inserted in said opening of said box body and provided with second connection means complementary to said first connection means to allow selective assembly of the respective control with said box body according to the function provided for said module.

Thanks to this combination of features, starting from a limited set of elements, it will be possible to assemble the auxiliary module according to a variety of configurations depending on the selected function, as it will be sufficient to change the single control, while maintaining the box body necessary for mounting on the casing.

Consequently, there will be considerable benefits both in terms of design and in terms of cost of realization, resulting in cost savings for the user.

Suitably, said box body of said auxiliary module may have a bottom wall having a central passage provided with means for rotatable anchoring of said module to said casing.

Preferably, the rotating anchoring means may be adapted to allow relative rotation between said module and said casing with a rotation angle greater than or equal to 90° around a central rotation axis while retaining said module and said housing axially constrained.

In this way, it is possible to vary the relative orientation between the module and the casing to independently adapt the respective positions to the specific anchoring mode of the casing to the fixed part of the barrier as well as the position of insertion of the driving means associated with the movable part.

Advantageously, said casing may comprise at least one pair of passages crossing it transversely along respective developing directions incident with each other and adapted to selectively enable the insertion of a member for fixing the casing to a fixed part of the access to be guarded.

In this way, it will possible to adapt the casing position to the specific opening mode of the access and apply ether to hinged opening or sliding openings, either right or left, without the need to provide auxiliary fastening members such as brackets or the like and without that it is necessary to house the driving means and possible centering means within a head orientable relative to the casing.

Suitably, said casing may house thereinside driving means with electronic operation for said switching means.

Moreover, said casing may comprise a centering hole adapted to cooperate with complementary centering means associated with the movable part of the access for recover any misalignments.

Preferably, said casing will be a monolithic body provided with said transverse passages, with said centering hole and with a seat for housing said electronically operate driving means and having a topo annular projection for engaging the central passage of said auxiliary module.

Thanks to this combination of features, a switch with an extremely simple and compact shape can be obtained, minimizing costs while at the same time meeting high security levels and ensuring high reliability.

Advantageous embodiments of the invention are obtained according to the dependent claims.

