Mechanism for speed-independent closing of contacts

Abstract

 The mechanism of the invention is designed such that a spring (5) is anchored to a lever (2) and an arm (6), so as to provide storage of energy by expanding when the lever (2) is subjected to an actuation force (1), releasing said energy immediately before a contact (8), movably secured to a pole bridge (7), connects with a contact (9), thereby enabling, independently of the actuation force (1), the contacts to achieve good connection and a contact spring (14) to be compressed. Such motion is ensured by a journaled wheel (3) traveling over the rest surface of the pole bridge (7).

Description

[0001] The present invention relates to a mechanism for speed-independent closing of contacts for energizing electrical loads in protective switching devices, wherein the mechanism and the design of the contacts allow its basic function to be performed, which is to say, the contacts to be switched on and off by means of a manually operated lever. The invention disclosed herein pertains to classes H01H71/10, H01H71/52, H01H5/06 of the international patent classification.

[0002] The technical problem adequately solved by the mechanism of the proposed design is to provide a configuration allowing the meeting speed of the contacts to be consistent and independent of the actuating lever.

[0003] Prior art solutions exploit various techniques, that is, physical principles, for operating the switch mechanism. Patents FR2717617, WO2005069335 and EP2061059 provide a switch mechanism, wherein the movable contacts are kept retained at a small distance from the stationary contacts, with contact springs being compressed during activation and the energy thusly stored being released subsequently in the final stage of the activation, following a withdrawal of the resistances of the movable contacts, the result being that the movable contacts clash against the stationary contacts at great speed, which makes the contacts bounce, so that they completely engage only later, slowly, by virtue of a further displacement of the pole bridge, whereon the mobile contacts are secured. In the event that the activation is stopped as soon as the contacts touch, the complete engaging of the contacts does not take place.

[0004] The switch mechanism as per WO2013003057 discloses an arrangement wherein the movable contacts are kept retained at a small distance from the stationary contacts, with a spring being stretched during activation, which spring is secured to a lever and to a movable contact, the energy thusly stored being released when a rest is pulled away in the final stage of the activation, so that the engagement of the contacts occurs instantly, with the contacts clashing with a maximal contact force. This substantial energy released in the moment of collision represents a disadvantage, given that said energy can not be cushioned, and potentially results in contacts bouncing.

[0005] The mechanism according to the present invention meets the requirement of switching contacts on independently of the speed of manual actuation, cushioning the impact of the contact material, while ensuring an immediate disconnection in the event of a fault condition present in the electrical circuit when the contacts meet (free tripping).

[0006] The invention shall be described with reference to an embodiment thereof and to the enclosed drawings, representing:

Figure 1

the mechanism in a switched-on state according to the invention in axonometric projection from one side;

Figure 2

the mechanism in a switched-on state according to the invention in axonometric projection from another side;

Figure 3

a side view of the mechanism in a switched-off state in cross section;

Figure 4

a side view of the mechanism immediately prior to being switched on in cross section;

Figure 5

a side view of the mechanism in a switched-on state in cross section;

Figure 6

a side view of the mechanism in a switched-off state;

Figure 7

a side view of the mechanism immediately prior to being switched on;

Figure 8

a side view of the mechanism in a switched-on state.

[0007] The mechanism according to the invention is composed of a lever 2, centrally journaled within the mechanism enclosure and having a cylindrical support whereon a tension spring 5 is attached, a journaled wheel 3 being mounted on a second cylindrical support. The lower end of the spring 5 is attached to a shaft 19, which penetrates an arm 6, pivotally anchored to the enclosure and connected to an arm 11, connected, in turn, to an arm 12. The arm 12 is retained by an arm 10, which is fastened to a fixed arm 17, mounted in the mechanism enclosure. All the arms are pivotally interconnected. A pole bridge 7 is journaled within the mechanism enclosure and serves as support for contacts 8, holding an arbitrary number thereof, in most cases two or four. The contact 8 is movably secured to the pole bridge 7 and biased by a contact spring 14. The spring 14 serves as a cushion when the contacts 8, 9 impact, as well as ensuring that the contacts 8, 9 are duly pressed together when in a switched-on state.

[0008] The spring 5 serves as an energy store, expanding from the beginning of activation up to the moment when the lever 2 tips over, which is to say, when the closing of the contacts proceeds independently of the actuation force 1. The journaled wheel 3 serves to prevent the contacts from closing ahead of the intended point and abuts against the pole bridge 7 with a force 16, which causes it to roll, while also serving as part of the locking mechanism once the connecting is completed.

[0009] In the switched-off state the force 13 of the return spring is exerted on the pole bridge 7, which is connected to the arm 12, 11 and 6, resulting in the spring 5 expanding and consequently keeping the lever 2 in the disconnected state with a force 4. The journaled wheel 3 is detached from the pole bridge 7. The contact spring 14 is partially compressed, biasing the contact 8 with a force 15 against the wall of the pole bridge 7, contacts 8 and 9 are separated.

[0010] Switching on proceeds in two stages; in the first stage, energy is stored in the spring 5 and the contact 8 approaches the contact 9, while in the second stage the energy stored in the spring 5 is released and utilized to connect the contacts 8, 9 and to compress the contact spring 14 which provides the required contact pressure.

[0011] The transmission of the actuating force 1 takes place via the lever 2, as it is moved from a switched-off state toward a switched-on state. The spring 5, being attached to the lever 2, starts expanding when the journaled wheel 3, fixed to the lever 2, abuts against the pole bridge 7. The journaled wheel 3 prevents the pole bridge 7 from swiveling uncontrollably and thus causes the spring 5 to extend and the contact 8 to slowly approach the contact 9. So the activation force 1 is employed for tensioning the spring 5 to the point where the journaled wheel 3 allows the pole bridge 7 to pivot and thus to push the contact 8 towards the contact 9 with a speed independent of the lever 2, and once the contacts 8 and 9 touch, to compress the contact spring 14.

[0012] The spring 5 is attached at one end to the lever 2 and at the other end to the shaft 19, which penetrates the arm 6, which is pivotally fixed at its center to the enclosure and pivotally coupled at its other end to an arm 11, which is, in turn, pivotally coupled to an arm 12, pivotally mounted on the pole bridge 7. Thus a force 4 via the arms 6, 11, 12 generates a force 18 which gives rise to a torque which acts on the pole bridge 7. The arm 12 is retained by the arm 10, secured in turn to a fixed arm 17. All the arms are pivotally interconnected. The arms 6, 11, 12 are positioned such that in the initial stage of activation they generate a small force 18, whereas in the final stage, despite the progressively diminishing force 4 in the spring 5, they generate a big force 18, since a big torque is required then to compress the contact spring 14, being that the force 15 increases. The anchoring of the spring 5, interposed between the lever 2 and the arm 6, serves as an energy store, the rolling of the journaled wheel 3 on the pole bridge 7 preventing the pole bridge 7 from swiveling while the spring 5 is being loaded.

[0013] In the event of a slight welding of the contacts 8, 9, the weld can be broken by means of the lever 2 via the journaled wheel 3, which pushes the pole bridge 7, thereby detaching the contact 8 from the contact 9.

Claims

1. Mechanism for speed-independent closing of contacts for energizing electrical loads in protective switching devices, wherein the mechanism and the design of the contacts allow the contacts to be switched on and off by means of a manually operated lever, characterized in that the mechanism according to the invention is composed of a lever (2), centrally journaled within the mechanism enclosure and having a cylindrical support whereon a tension spring (5) is attached, a journaled wheel (3) being mounted on a second cylindrical support, wherein the lower end of the spring (5) is attached to a shaft (19), which penetrates an arm (6), pivotally anchored to the enclosure and connected to an arm (11), connected, in turn, to an arm (12), wherein the arm (12) is retained by an arm (10), which is fastened to a fixed arm (17), mounted in the mechanism enclosure; a pole bridge (7) is journaled within the mechanism enclosure and serves as support for contacts (8), holding an arbitrary number thereof, in most cases two or four, wherein the contact (8) is movably secured to the pole bridge (7) and biased by a contact spring (14).

2. Mechanism according to Claim 1, characterized in that all the arms (6, 10, 11, 12, 17) are pivotally interconnected.

3. Mechanism according to Claim 1, characterized in that the journaled wheel (3) prevents the pole bridge (7) from swiveling uncontrollably and thus causes the spring (5) to extend and the contact (8) to slowly approach the contact (9) up to the point where the journaled wheel (3) allows the pole bridge (7) to pivot and thus to push the contact (8) towards the contact (9) with a speed independent of the lever (2), and once the contacts (8) and (9) touch, to compress the contact spring (14).

4. Mechanism according to Claim 1, characterized in that the spring (14) serves as a cushion when the contacts (8, 9) impact, as well as ensuring that the contacts (8, 9) are duly pressed together when in a switched-on state.

5. Mechanism according to Claim 1, characterized in that the anchoring of the spring (5), interposed between the lever (2) and the arm (6), serves as an energy store, the rolling of the journaled wheel (3) on the pole bridge (7) preventing the pole bridge (7) from swiveling while the spring (5) is being loaded.

6. Mechanism according to Claim 1, characterized in that in the event of a slight welding of the contacts (8, 9), the weld can be broken by means of the lever (2) via the journaled wheel (3), which pushes the pole bridge (7), thereby detaching the contact (8) from the contact(9).

Drawing