The present invention relates to a unidirectional spring part for retaining electric wires inside electrical connection terminal blocks and a terminal block comprising the spring.
It is known, in the technical sector relating to electrical connection devices such as terminal strips, connection boxes and the like, to use terminal blocks designed to be mounted on corresponding supports and provide frontal access to the means—normally of the screw type—for retaining the electrical connection wires which form the electric circuit.
It is also known that said means for retaining the end of the electric wire are normally designed with so-called sliders, movable in a direction perpendicular to the direction in which the wire is inserted, upon tightening a screw which causes retraction of the slider so as to grip the wire between the said slider and a counter plate extending parallel to the wire and designed to ensure the electrical continuity of the circuit inside the device.
As an alternative to said screw-operated sliders also known are wire clamping parts formed by a spring plate which is compressively deformed so as to allow opening of a slit and insertion of the wire inside its seat; once insertion has been completed the plate is released and, returning resiliently into the rest condition, ensures clamping of the wire against the counter plate and the electrical connection.
Although fulfilling their function, these known clamping means nevertheless have drawbacks which in the case of a screw-operated slider essentially are due to: the presence of the screw itself which tends to become loose over time, thus no longer ensuring the necessary clamping of the wire, and the fact that the said wire is clamped between two flat surfaces with complex forms which are difficult to produce, resulting in unevenness unable to ensure full electrical contact between wire and terminal block.
In the case of the spring, instead, the drawback is associated with the resilient force which must be imparted to the plate in order to ensure adequate clamping of the wire, which resilient force must be increased with an increase in the electrical loads and therefore the cross-section of the wire to be retained; in terminal blocks of the known type the resilient retaining means consist of parts constrained to supports by means of welds, rivets and the like, which complicate assembly and substantially reduce the possibility of adjusting the resilient force to be applied.
The technical problem which is posed, therefore, is to provide a spring part for retaining electric wires, in particular for use inside connection devices such as terminal blocks, connection boxes, wired-circuit switchboards and the like, which has small overall dimensions, but at the same time is able to withstand a high electrical load and which, in addition to facilitating assembly, also facilitates adjustment of the force to be imparted depending on the cross-section of the wire to be retained.
In connection with this problem it is also desirable that this retaining part should be easy and inexpensive to produce, be able to be used equally well with different types of electrical connection devices and be able to be easily operated by any user using normal standard tools.
These results are achieved according to the present invention by a unidirectional spring part for retaining electric wires inside electrical connection terminal blocks according to the characteristic features of the invention and a terminal block comprising said spring part according to the characteristic features of the invention.
Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings in which:
a shows a schematic view of the spring/plate engaging sequence;
As shown in
The vertical arm 111 can be joined to a U-shaped base 120 comprising: a first vertical arm 121 for connection to the vertical arm 111, a second vertical arm 122 with a free end 122a and a straight section 123 connecting together the two vertical arms.
With this configuration of the spring part 100 it is possible to perform simple and rapid engagement thereof with the electrical connection conductor or plate 200 (
The electrical connection plate 200 can have a U-shaped form with substantially vertical arms 211 and a horizontal connecting section 212. The horizontal connecting section 212 can include an eyelet 213 with a longitudinal dimension greater than the longitudinal dimension of the base 120 of the spring 100 and a hole 214 with a longitudinal dimension slightly greater than the width, in the longitudinal direction, of the arm 122 of the base 120 of the spring 100 so that the second vertical arm 122 of the base 120 can be inserted in the hold 214.
In one embodiment of the invention, the hole 214 can be arranged at a distance from the edge of the eyelet 230 substantially coinciding with the length, in the longitudinal direction, of the longitudinal section 123 of the base of the spring so that, when the vertical arm 122 of the base 120 is inserted inside the hole 214 in the sequence schematically shown in
In the position where the spring 100 is secured to the plate 200, the free end 112a of the arm 112 of the spring itself bears against the vertical arm 211 of the plate 200 against which it presses with a pre-tensioning force determined by the size of the spring.
In accordance with one embodiment of the invention, the free end 211a of the vertical arms 211 of the plate 200 can be bent outwards at an obtuse angle so as to form a tooth which can be inserted inside a corresponding seat 315 of a terminal block 300, as will appear more clearly below.
With this embodiment of the retaining spring part and the electrical connection plate it is possible to provide a terminal block 300 according to the present invention which comprises an insulating body 310 forming the container for the conducting part 200 with which the spring 100 provides means for retaining the free end 1a of the electric wire 1 are associated.
In greater detail, said insulating body 310 has a frame formed so as to define at least one front side 310a and at least two respective sides 310b situated opposite each other.
The insulating body 310 can include, formed inside it:
a first pair of seats 312 which are open in the transverse direction Y-Y and symmetrical with respect to a central axis parallel to the vertical direction Z-Z and which have a substantially vertical outer side 312a and an inner side 312b shaped so as to match the profile of the spring part 100; and,
a second pair of seats 315 respectively arranged on opposite sides of the seats 312 towards the sides 310b and in turn symmetrical with respect to the axis Z-Z and designed to seat the free inclined end 211a of the arm 211 of the contact plate 200, so as to ensure stable retention of the conducting part 200 on the insulating body 310.
The front wall 310a of the insulating body 310 can be provided with:
a second pair of substantially vertical seats 316 close to the vertical axis of symmetry and with dimensions corresponding to the arm 122 of the base 120 of the spring 100 and designed to seat said arm when the terminal block is assembled;
a pair of first openings 313 extending in the vertical direction Z-Z, substantially arranged above the respective seat 312 and designed to connect the latter with exterior so as to allow insertion of a tool T; and,
a pair of holes 317 with a vertical axis Z-Z, arranged in a position situated further outwards than said first openings 313 and connected to the respective seat 312 with which they communicate for insertion of the bare wire 1a in the vertical direction Z-Z.
As shown in the two halves of
removing the front cover which is identical to and arranged opposite the frame 311 and is therefore not shown,
inserting, in the transverse direction Y-Y, the conducting part 200 already engaged with the spring 100, so that the inclined end 211a, the spring means 100 for retaining the wire 1 and the vertical arm 122 of the base 120 are arranged inside the respective seats 315, 312, 316;
the cover is closed;
inserting the tool T inside the hole 313 so as to act on the arm 112 of the spring 100 and pushing it so as to free the end 112a from the vertical arm 211 of the electrical conductor 200;
inserting the wire 1 inside the respective entry seat 317 so that the bare end 1a penetrates toward the bottom of the seat 312;
extracting the tool, thus releasing the resilient arm 112 of the spring 100 so that it clamps the wire and tightly presses it against the vertical arm 211 of the conductor 200.
As shown in
In this embodiment, the seat 1312 is rotated through 90° outwards and the holes 1317 for insertion of the wire 1 and 1313 for insertion of the tool T have a longitudinal axis X-X, being formed in the sides 1310b of the terminal block 1300.
The electrical connection part 1200 has a straight longitudinal section 1212 which is bent at 90° in the vertical direction Z-Z so as to form:
a vertical arm 1212a in which the eyelet 213 and the hole 214 are formed and
a horizontal arm 1211 with the end 1211a bent at an obtuse angle for insertion inside the respective seat 1315.
The horizontal arm 1211 of the conductor 1200 can also have (
Correspondingly, the spring 100 is rotated through 90° towards the sides 1310b of the terminal block so that the resilient arm 112 presses against the horizontal arm 1211 of the conductor 1200.
Assembly and operation of the terminal block are entirely similar to that already described in connection with
In detail, the spring 1100 has an end part of the arm 1112 which has a cut 1112f in the longitudinal direction terminating in a through-hole 1112b so as to divide said end part of the arm into two strips 1112c and 1112d which are independent of each other and have identical resilient properties owing to the hole 1112b; with this solution it is therefore possible to insert and retain two wires instead of one, which may also have a different cross-section, against the contact plate 200;1200.
Advantageously the free end 1112a of each strip has an incision 1125 suitable for receiving partially the end 1a of the wire 1 and facilitating the insertion thereof without any obstacles and retention thereof in position.
In one embodiment of the invention, the contact plate 2200 can include an arm 2211 with a transverse eyelet 2216 situated opposite the entry hole 313 in the insulating body of the terminal block and designed to allow the insertion of the tool T for actuating the arm of the spring 100,1100.
It is therefore clear how the spring according to the present invention can be quickly and easily engaged with the conducting part of a terminal block for electric cables.
In addition, the particular form of the spring and the engaged arrangement of the spring and conductor result in a substantially unidirectional terminal block in the sense that, once the wire has been inserted, it is prevented from coming out by the free end of the resilient arm of the spring which reacts with greater force the more the wire is pulled outwards.
In addition, it is possible to use the same terminal block for a wide range of wires of varying cross-section, also for high electrical loads, since there are no physical and/or geometrical constraints as regards the conductor cross-section which may be used, it being possible in particular to make use of the entire width, in the transverse direction, of the arm 112;1112 of the spring 100;1100 for ensuring the electrical contact with the plate 200;1200;2200.
It is also clear how, as a result of the particular symmetrical form of the conducting part and the spring, it is possible to reduce the number of parts to be produced and stored since the same component may be equally well used for a right-hand or left-hand design merely by means of correct positioning inside the insulating body of the terminal block.
Number | Date | Country | Kind |
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MI2008A000673 | Apr 2008 | IT | national |