Electromagnetic relay equipped with bi-stable safety test push-button

Abstract

 There is described an electromagnetic relay comprising a cover (1) containing a bi-stable test push-button (16), that realizes a temporary and a fixed contact positions; the test push-button (16) is equipped with retainer means (20̸) to obtain the fixed position by pushing and simultaneously rotating it; and the cover (1) is equipped with means (34) to house the push-button (16) preventing its release in case of fixed closure.
Moreover, the cover (39) can be equipped with a slider (40̸) comprising means (46) to allow temporary pushing and means (42, 44) to allow permanently pushing the push-button (48) into its contact position.

Description

[0001] The present invention refers to an electromagnetic relay equipped with bi-stable safety test push-button.

[0002] Various types of relay are known in the art, these relays being equipped both with Light Emitting Diodes (LED) indicating the active and inactive status of the relay itself, and with test push-buttons: by pressing these push-buttons, a user is able to close circuit contacts to detect its operation.

[0003] Currently known test push-buttons are of two types: the first type, so-called "mono-stable", allows, by pressing it, to close the circuit for the test, but, once released, returns into its rest position, opening the circuit again.

[0004] The second type of known push-button is the so-called "bi-stable" one (a type of bi-stable push-button is manufactured by Relpol) and is configured in such a way as to assume a circuit closing position both temporarily, after having pressed it, and permanently, that is by displacing it into a fixed position. This possibility, however, poses some problems, above all linked to plant and people safety: first of all, if the push-button is forgotten into its fixed actuation position, the circuit remains closed even when it should not be (that is, at the end of testing) and could damage plants or machines controlled thereby. Moreover, given the current configuration of known push-buttons, their fixed actuation can be simply and quickly carried out, even casually and by untrained people or by people that have no intention to carry out tests: all these generate risks that can be easily thought of.

[0005] Object of the present invention is solving the above prior art problems, providing an electromagnetic relay equipped with a bi-stable test push-button that allows realizing the two working positions in a simple, but simultaneously efficient way, and above all a safe way, since inadvertent and undesired actuations are practically prevented.

[0006] The above and other objects and advantages of the invention, as will appear from the following description, are obtained by means of an electromagnetic relay equipped with bi-stable safety test push-button as disclosed in Claims 1 and 4. Preferred embodiments and non-trivial variations of the present invention are disclosed in Claims 2, 3, 5 and 6.

[0007] The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

• Figure 1 is a simplified side view of a relay equipped with an embodiment of a bi-stable push-button according to the present invention, in its rest position;
• Figure 2 is a side view similar to Fig. 1, but that shows the push-button actuated by a temporary pressure;
• Figure 3 is a side view similar to Fig. 1, but that shows the push-button actuated as closed in a fixed position;
• Figure 4 is a bottom view of the cover of the embodiment of the electromagnetic relay of the present invention shown in Fig. 1;
• Figure 5 is a side sectional view of the cover shown in Fig. 4;
• Figure 6 is a top view of the cover shown in Fig. 4;
• Figure 7 is a side view of the test push-button that can be used in the embodiment of the relay shown in Fig. 1;
• Figure 8 is a front, partially sectioned view of the test push-button in Fig. 7;
• Figure 9 is a top view of the test push-button in Fig. 7;
• Figure 10̸ is a top view of a further embodiment of the electromagnetic relay of the present invention;
• Figure 11 is a side cross-sectional view of the relay in Fig. 10̸; and
• Figure 12 is a front cross-sectional view of the relay in Fig. 10̸.

[0008] With reference to the Figures, the electromagnetic relay of the present invention is substantially composed of a cover 1, usually made of transparent plastic material, and of a body 3 including a support base 5 and a set of known electric components, that will not be described hereinbelow, apart from the major ones that have some relevance to the present invention.

[0009] The base 5 of the relay body 3 is equipped with a set of lamellar terminals 7, 7', 7'' for the adequate connections, some of these terminale 7, 7' being equipped with enlarged internal ends 9, 9' in turn equipped with contacts 11, 11'. Between the two pairs of terminals 7, 7', and therefore of contacts 11, 11', a contact member 13 is placed (commonly realized as small copper blades) that in turn is equipped with two contacts 14, 14' on its two sides, and that can assume two different contact positions, in which the two different pairs of contacts 11, 11' will be contacted. The two operating positions of the contact member 13 are controlled by energizing or de-energizing a coil 15, that attracts or releases the contact member 13 itself, that is supported by a support 15' and is taken back to its rest position by a resilient member 15''.

[0010] All operations that have been briefly described above are well known in the field of electromagnetic relays. The operation for these relays is commonly controlled by means of push-buttons that allow manually and mechanically operating the contact member 13 so that it is able, by striking and pushing the tongue 17, to make it assume, like in the case shown in Fig. 2 and 3, the operating position where lower contacts 11' are connected. Test push-buttons can be actuated by pushing and then releasing them, thereby recreating the two operating conditions respectively shown in Fig. 1 and in Fig. 2 and 3, or they can be taken to the position shown in Fig. 2 and 3 and left there to subject the relay to longer contact tests. In this case, the position reached is the one shown in Fig. 3. The push-button 16 used in the relays of the present invention is of this second type, and is therefore called "bi-stable", because it can assume both test positions, that is the temporary and the permanent one.

[0011] The push-button 16 of the present invention, however, is different from the known ones because, in order to actuate it, a set of specific operations are necessary, that make a casual actuation as well as an actuation carried out in any undesired way, impossible. For this purpose, the push-button 16 is realized, in a first embodiment thereof, as best shown in Figures 7 to 9. In these Figures, the push-button 16 is composed of a small elongated cylinder 18, at one end of which a projection 20̸ is obtained so that the push-button 16 gets the shape of a key. Moreover, the small cylinder 18 is equipped with a tooth 21 whose function is preventing the cylinder from coming out of the relay in its rest position. At the opposite end of the small cylinder 18, the push-button is equipped with an elongated head 22 shaped as an arrow with a bit 24 on one side and a seat 26 for screwdrivers with normal or star bit.

[0012] In order to efficiently actuate the push-button 13, the relay of the present invention must further be equipped with a suitable cover 1, that is best shown in Figures 4 to 6. In these Figures, the cover 1 is shaped in order to have a housing 28 for the push-button 16 in its rest position, and an hole 30̸ with a keyway 32. The hole allows inserting the small cylinder 18 of the push-button 16 inside a cylindric housing 34, also shaped in order to receive the cylinder 18 with the key projection 20̸ into the seat 32. Finally, a plurality of holes 36 with varying diameters are provided, said holes being adapted to contain corresponding projections of the front plate 33 of the relay that will be placed on the upper side of the cover 1. The cover 1 is finally equipped with a special safety feature, composed of a retainer tooth 38 made of plastic material, that can be easily broken down and detached from the cover 1 if one wishes to actuate the push-button 16 in its permanent test contact position. Otherwise, this retainer tooth 38 does not allow opening the push-button 16 by rotating it, only allowing it to be operated by pressing and releasing it as typical of mono-stable push-buttons.

[0013] The operation of this first embodiment of the electromagnetic relay of the present invention will now be described, with particular reference to Fig. 1 to 3.

[0014] The push-button 16 in Fig. 1 finds itself in a rest position, where a connection occurs between lower contacts 11 of the terminals 7 and upper contacts 14 of the contact member 13. From this position, by a finger pressure, the upper contacts 11' of the terminals 7 can be brought into connection with the lower contacts 14' of the contact member 13, as better shown in Fig. 2. Upon releasing the finger pressure, the push-button 16 will go back to the position in Fig. 1: it will therefore operate as mono-stable push-button.

[0015] If one wishes to operate the push-button 16 as bi-stable, it will be firstly be necessary to break down and detach the retainer tooth 38 from the cover 1 and then, by acting through a suitable screwdriver, to push and simultaneously rotate (in a counterclockwise and upward direction with respect to the drawings) the push-button 16: in this way, this pushing actuates the connection between contacts 11' and 14' as shown in Fig. 2, and the rotation frees the projection 20̸ from the keyway into the cylindric housing 34, so that, into the final contact position shown in Fig. 3, the projection 20̸ abuts against the cylindric housing 34 and keeps the push-button 16 into the connection position in Fig. 3.

[0016] If one wishes to take back the push-button 16 to its rest position in Fig. 1, it will suffice to push with a finger the push-button 16 by rotating it and to snap-take it back into the adequate housings 28 and 34 provided on the cover 1.

[0017] Figures 10̸ to 12 show a second embodiment of the electromagnetic relay of the present invention, that performs the main functions already pointed out for the first embodiment thereof.

[0018] According to this further embodiment, in the relay cover 39 a slider 40̸ is provided, this slider being equipped with a recess 42 for pushing it with the fingers, and with a plurality of retainer notches 44, in addition to an opening 46 (in the embodiments shown in a squared shape) through which it is possible to access to the head 47 of the bi-stable type of push-button 48. The slider 40̸ is so shaped as the walls of the recess 42 can pushingly abut on an appendix 50̸ of the push-button 48, this appendix 50̸ making a sort of inclined plane: the cooperation between this appendix 50̸ and the walls of the recess 42 allows taking the push-button 48 progressively from its rest position to its fixed contact position with common contacts (not shown).

[0019] The push-button 48 is equipped with an elongated stem 52 on which the above appendix 50̸ is placed, and on which retainer teeth 54 are provided to prevent it from coming out of the cover 39.

[0020] The operation of this embodiment of the relay of the present invention provides a normal pushing operation of the push-button 48 to temporarily close and open the contact when testing. If, instead, one wishes to fixedly close the contacts, it is simply necessary to push the slider 40̸ towards the cover 39 exterior through a sliding actuated, for example, by one's fingers: in this way, the walls of the recess 42 will push the appendix 50̸ and thereby the push-button 48 downwards, that is towards the contact position, and they will keep it pressed in such position till the rest status is recovered, always by sliding the cursor 40̸ backwards. The retainer notches 44 establish and make the two final rest and outgoing positions of the slider 40̸ unmovable.

Claims

1. Electromagnetic relay substantially comprising:

- a body (3) equipped with a base (5) containing an energizing coil (15) adapted to connect contacts (11, 11') of terminals (7, 7') to contacts (14, 14') of contact members (13);

- a cover (1) adapted to be inserted onto said cover (3); and

- a test push-button (16) of the bi-stable type, that is adapted to realize a fixed closing position of the contacts (11', 14') and a temporary closing position of the contacts (11', 14');
   characterized in that:

- said cover (1) is equipped with retainer means (38) to prevent the undesired actuation, in the fixed closure, of said test push-button (16);

- said test push-button (16) is equipped with retainer means (20̸) to perform the fixed closure position by pushing and simultaneously rotating said push-button (16); and

- said cover (1) is equipped with means (34) to house said test push-button (16) preventing the release thereof during the fixed closure step of the contacts (11', 14').

2. Electromagnetic relay according to Claim 1, characterized in that said retainer means (20̸) of said test push-button (16) are composed of a projection (20̸) that realizes a key with a small cylinder (18) of which said test push-button (16) is composed, said test push-button (16) being further equipped with an elongated head (22) with a seat (26) for a screwdriver; and

- said cover (1) is equipped with a cylindric housing (34) containing a seat (33) for said projection (20̸).

3. Electromagnetic relay according to Claim 1 or 2, characterized in that said retainer means (38) of said cover (1) are composed of a retainer tooth (38) that is able to be broken down and detached from said cover (1).

4. Electromagnetic relay substantially comprising:

- a body (3) equipped with a base (5) containing an energizing coil (15) adapted to connect contacts (11, 11') of terminals (7, 7') to contacts (14, 14') of contact members (13);

- a cover (39) adapted to be inserted onto said cover (3); and

- a test push-button (48) of the bi-stable type, that is adapted to realize a fixed closing position of the contacts (11', 14') and a temporary closing position of the contacts (11', 14');
   characterized in that:

- said cover (39) is equipped with a slider (40̸), said slider comprising means (46) to allow temporarily pushing said push-button (48) in a contact position, and means (42, 44) to allow permanently pushing said push-button (48) in the contact position.

5. Electromagnetic relay according to Claim 4, characterized in that said means (46) to allow temporarily pushing said push-button (48) are composed of an opening (46) through which it is possible to have access to the head (47) of said push-button (48).

6. Electromagnetic relay according to Claim 4 or 5, characterized in that said means (42, 44) to allow-permanently pushing said push-button (48) are composed of a pushing recess (42) and of a plurality of retainer notches (44), the walls of said pushing recess (42) cooperating with an appendix (50̸) of said push-button (48) to progressively take said push-button (48) from its rest position to its fixed contact position.

Drawing