This invention relates to an electrical connection device .

More specifically, this invention relates to an electrical connection device of the rotary type, generally known as "rotary joint", designed to electrically connect two elements rotatable relative to each other.

Some examples of electrical connection devices of the rotary type are also applied to electric motors but they have alternating contact connection features as described in the prior art documents: US 3 387 156, US 2 498 346, GB 2 203 294, DE 103 44 717 and CN 202 050 149. As is known, the rotary joints are mainly used in movable apparatuses, such as, for example, the rotary control cabin machines, for transmitting the current between the control cabin and the mechanical actuators mounted on a fixed part of the machine. These connection devices generally comprise a first group of static electrical connectors, associated with the fixed structure of the machine, and a group of rotary electrical connectors, associated with the movable part of the machine.

More specifically, the movable electrical connectors comprise a series of annular elements (generally made of metal material) positioned next to each other and suitably insulated from one another. Each annular element has a cylindrical inner surface to which an electrical connection terminal is engaged for the power supply to the electromechanical units of the movable part of the machine (control cabin) .

The annular elements coupled together form a single tubular body suitably mounted on a frame rotatable about the longitudinal axis of the tubular body.

The static electrical connectors, comprise, on the other hand, a series of clamping elements, fixed on a supporting frame engaged with the fixed part of the machine .

Each clamping element is associated with a respective annular element to form an electrical connection. More specifically, each clamping element has a pair of supporting arms, each of which having a first end supporting a sliding contact element (generally known as "brush") , and a second end anchored to the supporting frame. The brush rests on the cylindrical outer surface of the annular element in such a way as to define a passage of electricity also during the rotation of the annular element.

Moreover, the clamping elements have respective electricity cables connecting the brushes with respective terminals supported at the second end of the arms. The terminals allow a power supply generator of the fixed part of the machine to be associated electrically with the electricity cables, in such a way as to transfer electricity to the brush and therefore the annular element.

Further, each arm of the clamping element has a return spring designed to keep the clamping element always adherent to the annular element. In other words, the spring always keeps the brush positioned on the end of the arm adherent against the outer surface of the annular element. In this way, the electrical connection is always guaranteed between the static electrical connector and the movable electrical connector.

However, the electrical connection devices described above have a major drawback, mainly due to the structural complexity of the group of static electrical connectors .

In effect, it should be noted that for each fixed electrical connector there is a high number of components which form the entire clamping element.

The presence of the return spring, the electrical connection cables, the supporting arms and all the connecting units between the arms and the frame therefore a complex structure, with large dimensions and high production costs.

It should also be considered that the maintenance operations for the device are particularly complex given the structural complexity defined by the high number of components of each single clamping element.

In this context, the aim of this invention is to provide an electrical connection device which is free of the above mentioned drawbacks.

More specifically, the aim of this invention is to make an electrical connection device which is structurally simple and therefore with small dimensions and limited production costs.

In more detail, the aim of this invention is to make a device which is able to reduce to a minimum the number of components used to make the electrical connection between the movable connectors and the static connectors .

The technical purpose indicated and the aim specified are substantially achieved by an electrical connection device with the technical features described in one or more of the appended claims.

Further features and advantages of this invention are more apparent in the non-limiting description which follows of a preferred embodiment of an electrical connection device as illustrated in the accompanying drawings, in which:

- Figure 1 is a partly exploded perspective view of the connection device according to this invention;

Figure 2 is an exploded perspective view of a construction part of the device of Figure 1; and

- Figure 3 is a transversal cross section of the construction part shown in Figure 2;

With reference to the accompanying drawings, the numeral 1 denotes in its entirety an electrical connection device according to this invention.

The device 1 comprises at least one first connector 2 and at least one second connector 3, electrically connected to each other and at least one of which can move relative to the other.

Advantageously, the device 1 comprises a plurality of first connectors 2, positioned next to each other and engaged with each other to form a tubular body 4. The tubular body 4 is rotatable about a respective longitudinal axis in known manner and therefore not described in detail.

The device 1 also comprises a plurality of second connectors 3, which are also positioned next to each other in such a way as to be electrically associated with the corresponding first connectors 2. With reference in particular to Figure 1, it should be noted that the second connectors 3 are coupled in an alternating fashion about the tubular body 4. In other words, two adjacent first connectors 2 are in electrical contact with two respective second connectors 3 positioned one opposite the other. In this way, two columns 5 of second connectors 3 are defined, to make the entire device 1 more compact and less bulky. It should also be noted that the first and the second connectors 2 , 3 can be positioned inside a box-shaped body 6, partly illustrated in Figure 1, to isolate the device 1 from the outside environment.

With reference to Figures 2 and 3, it should be noted that each first connector 2 comprises an annular body 7, made of electrically conductive material such as, for example, metal, and forming a cylindrical outer surface 7a coupled with the respective second connector 3, as described in more detail below.

The annular body 7 also has a cylindrical inner surface 7b associated with a terminal 8 for electrical connection to a user device. Advantageously, the terminal 8 is connected in known manner to a user device (not illustrated as not forming part of this invention) to which electricity must be transferred. For example, if this device 1 is used for rotary control cabin machines, the terminal 8 is connected to the electrical apparatuses positioned in the control cabin.

With reference to Figure 1, the first connector 2 also comprises a supporting body 9, made of electrically insulating material, and associated with the inner surface 7b of the annular body 7. The supporting body 9 has a substantially annular shape and has respective fastening elements 9a which can be coupled to. connecting pins 10a of a rotary support 10, designed to rotate all the first connectors 2. As shown in Figure 1, the rotary support 10 has three connecting pins 10a extending along the longitudinal extension of the tubular body 4 and each of which inserted in a respective fastening element 9a of the supporting body 9. The first connectors 2 are positioned next to each other on the rotary support 10 and suitably insulated from each other by insulators of known type and therefore not described and illustrated in detail. Advantageously, the rotary support 10 is anchored to rotatable mechanical parts, for example the control cabin of a machine.

With reference to Figures 2 and 3, it should be noted that each second connector 3 comprises supporting portion 11 made of electrically conductive material. Preferably, the supporting portion 11 comprises a metal wire 12. Advantageously, the material used for the metal wire is a copper-beryllium alloy.

It should be noted that the material used for the metal wire 12 also has elastic deformation properties, for using the wire 12 as a spring for coupling with the above-mentioned annular body 7.

The supporting portion 11 comprises at least one first end 14 designed to support a sliding contact element 13, and a second end 15 anchored to a frame 16 for supporting the second connectors 3.

In more detail, the supporting portion 11 extends substantially in a "U" shape, forming two parallel or - slightly diverging first ends 14, each of which is associated with a respective sliding contact element 13. In this situation, it should be noted that the second end 15 of the supporting portion 11 is interposed between the two first ends 14; and

extends transversally to the extension of the first ends 14.

The first connector 2 is therefore housed in an area defined between the first ends 14 and the second end 15 of the supporting portion (Figure 3).

The sliding contact element 13 comprises a brush, resting on the outer surface 7a of the respective annular body 7. Advantageously, during rotation of the first connectors 2, the outer surface 7a of the annular body 7 slides on the brush in such a way as to always form a contact for the passage of electricity. The sliding contact element 13 is made of electrically conductive material and is coupled directly on the metal wire 12. Consequently, the passage of electricity is guaranteed between the first and the second connectors 2, 3 by means of the sliding contact element 13 and the metal wire 12.

Moreover, it should be noted that the annular body 7 is coupled to two contact elements 13 positioned on the first ends 14 of the respective supporting portion 11. The contact elements 13 are positioned at diametrically opposite points of the annular body 7.

Advantageously, the elastic properties of the wire 12 allow the elements 13 of each supporting portion 11 to be always kept adherent on the respective annular body 7.

In effect, the first ends 14 are elastically deformed and fitted around the annular body 7 for pressing the respective sliding contact elements 13 on the cylindrical outer surface 7a of the annular body 7.

The second end 15 of the metal wire 12 is associated with a connection terminal 17, designed to be electrically associated with an electric power unit which is not illustrated and described as of known type and not forming part of this invention. The electric power unit normally comprises a generator positioned in the fixed part of the machine. Consequently, the electric current entering from the terminal 17 is transferred through the metal wire 12 to the contact element 13 and then to the annular body 7.

The supporting portion 11, consisting of the metal wire 12, also comprises coupling means 18 interposed- between- each sliding contact element 13 and the supporting portion 11. In detail, the coupling means 18 have a portion 19, with a "C" shape and designed to contain a respective contact element 13. It should be noted that the portion 19 and the contact element 13 have through holes 20, which are coaxial and coincident, inside of which the first end 14 of the wire 12 can be inserted. In this way, the contact element 13 and the respective portion 19 with a "C" shape are engaged and slidable along the first end 14. The coupling means 18 also comprise a screw 21 for securing and adjusting the contact element 13 on the respective first end 14.

This screw 21, preferably comprising a grub screw, is screwed inside the portion 19 for interfering with an end stretch of the first end 14 of the wire 12 (Figure 3) .

Each second connector 3 also comprises a hooking element 22 for engaging the supporting portion 11 with the above-mentioned supporting frame 16.

More specifically, the hooking element 22 is made of electrically insulating material, preferably plastic, and has a substantially parallelepiped shape forming an upper surface 22a.

The surface 22a has a seat 23 substantially shaped to match the shape and the dimensions of the second end 15 of the supporting portion 11, comprising the metal wire 12. In this way, the second end 15 of the supporting portion 11 is housed and anchored inside the seat 23.

The fastening element 22 also has at least one through opening 24, preferably two openings 24 next to each other, each of which designed to receive a rod 25 of the supporting frame 16.

More specifically, as shown i Figure 1, the frame 16 has two pairs of rods 25, positioned on opposite sides relative to the tubular body 4, and each of which forming the column 5 of second connectors 3. The rods 25 ^' are in turn attached to a supporting flange, which is not illustrated and described as of known type, associated with the fixed part of the machine.

In this way, the second connectors 3 are fitted and positioned next to each other on a pair of rods 25.

Advantageously, the device 1 is structurally simple as it comprises a limited number of components.

This advantage derives from the fact that the only supporting portion 11, comprising the metal wire 12, is made of material which allows the passage of electricity and at the same time is elastic for pressing the contact elements 13 on the first connector 2. In other words, the metal wire 12 has the triple function of supporting the contact elements 13, transferring the electricity and actuating a spring action.

Consequently, the mechanical components provided for each single function of electrical connector, support and spring are eliminated.

Consequently, the entire device 1 is less complex, less bulky and less expensive.

Moreover, the coupling means 18 allow for simpler and faster adjustment and maintenance operations on the sliding contact elements 13. This advantage is due to the fact that the contact elements 13 are not engaged directly and in a stable manner on a respective arm, but are mounted and adjusted on the end 14 of the wire 12 using the above-mentioned coupling means 18.