IE910836A1 - A Miniature Circuit Breaker Handle Assembly - Google Patents

Abstract

(Fig. 1) A handle assembly (2) is disclosed for a miniature circuit breaker (1). The handle (15) is biassed by a torsion spring (22) which is anchored at one end to the casing 5 brackets (3). The free end engages a stop (20) on a link arm (19) in the open position of a handle (15). This maintains the link arm (19) in contact with a switch arm (5). For the closed position of the handle (15) a stop (18) has moved into position to engage the free end of the spring (22) so that the 10 spring acts directly on the handle (15) to provide contact pressure via the link arm (22) and the switch arm (5). Thus, in a simple way the problems of providing contact pressure for the closed position of the handle and pressure to maintain the link arm in contact with the switch arm for the open position 15 is provided by a single spring.

Description

Introduction The present invention relates to a miniature circuit breaker handle assembly of the type comprising a handle rotatably mounted on a casing and biased between open and closed toggle positions, and a link arm acting on a movable contact.

German Patent Specification No. DE 3200325 (Licentia) discloses a handle assembly in which the link arm has a rigid extension extending at an angle with respect to the portion of the arm engaging a movable contact. In the open position of the handle, the fact that the extension piece is at an angle to the link arm causes the tension spring to exert a turning force on the link arm to keep it in engagement with the movable contact. In the closed position, the extension piece is co-linear with the tension spring and so the tension spring does not effectively act on the link arm but only on the handle via the pin connecting the link arm to the handle. It appears that such a handle assembly would be difficult to manufacture as it is essential that the various parts are arranged precisely in position with a very small tolerance.

Any deviation from a small tolerance range would result in a turning force being exerted on the link arm in the closed position. ό t ; The present invention is directed towards providing an improved handle assembly for a miniature circuit breaker which overcomes the above-mentioned problems and which is relatively simple to manufacture and reliable in operation.

Statements of Invention According to the invention, there is provided a miniature circuit breaker handle assembly of the type comprising a handle rotatably mounted on a casing, spring bias means acting on the handle to bias it to closed and open toggle positions and a link arm for acting on a movable contact, wherein the spring bias means comprises a torsion spring mounted coaxially with the handle and having an anchored end and a free end, the link arm having a stop located to engage the free end when the handle is in the open position and the handle having a stop located to engage the free end and move it from the link arm stop when the handle is in the closed position.

Preferably, the anchored end is anchored to the casing.

In one embodiment, the torsion spring is mounted underneath the handle, the link arm stop depends downwardly from the link arm and the handle stop depends downwardly from the handle.

Preferably, the handle stop is formed by a pivot pin for the link arm.

Claims (3)

1. The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:Fig. 1 is a diagram showing a miniature circuit breaker handle assembly in an open position; and Fig. 2 is a diagram showing the handle assembly in the closed position. Detailed Description of the Invention Referring to the drawings, there is illustrated portion of a miniature circuit breaker 1, having a handle assembly 2 of the invention. The miniature circuit breaker 1 comprises a movable contact 4 having a switch arm 5 pivotally connected to it. The switch arm 5 is acted on by a contact spring 6 which is anchored to the casing. The movable contact 4 is for contact with a fixed contact 7 and when in the closed position, current passes through a terminal 8, a bi-metallic element 9, the movable contact 4, the fixed contact 7 and a solenoid 10. The handle assembly 2 comprises a handle 15 which is rotatably mounted on a casing 3 at a handle pin 16. A latch 17 is pivotally connected to the handle 15 at a latch pin 18. The latch pin 18 extends downwardly from the handle 15. Also connected to the handle 15 at the latch pin 18 is a link arm 19 which has a downwardly depending stop 20 shown by interrupted lines. The link arm 19 engages the free end of the switch arm 5. The casing 3 includes an integral stop 21, and mounted beneath the handle 15 is a torsion spring 22 which has two ends biased towards each other as shown by the arrows A. One end of the torsion spring 22, namely, an anchored end is anchored at the casing stop 21. The other end of the torsion spring 22, namely, a free end is shown in Fig. 1 engaging the link arm stop 20. In use, when the circuit breaker 1 is in the open position the handle 15 is at it's extreme clockwise position about the handle pin 16 and the link arm 19 does not exert pressure on the switch arm 5. However, because the free end of the torsion spring 22 acts on the link arm stop 20, the link arm 19 is kept in contact with the switch arm 5 and even after the circuit breaker is tripped, this contact is maintained. Further, in this position, the torsion spring 22 acts on the handle 15 to bias it to the open toggle position through the link arm 19 and the latch pin 18. When the circuit breaker 1 is to be switched on, the operating handle 15 is rotated in an anti-clockwise direction. As this happens, the latch pin 18 moves in an anti-clockwise direction relative to the free end of the torsion spring 22 until an intermediate stage is reached when it abuts against the free it' e, * ,W' y end. At this stage, the free end is in contact with both the latch pin 18 and with the link arm stop 20. Further movement of the handle 15 in the anti-clockwise direction results in the latch pin 18 pushing the free end of the torsion spring 22 in an anti-clockwise direction away from the link arm stop 20. This continues until the handle 15 reaches it's extreme anticlockwise position (Fig. 2) in which it will be seen that the torsion spring acts only on the latch pin 18. Accordingly, in the open position as shown in Fig. 1 the torsion spring 22 acts on the link arm 19 because it engages the link arm stop 20 and also on the handle 15 because the link arm 19 is pivotally connected to the handle 15 at the latch pin 18. This provides the open toggle position bias and bias on the link arm 19 to maintain it in contact with the switch arm 5. However, in the closed position as shown in Fig. 2, the torsion spring acts only on the handle 15 via the latch pin 18 and not on the link arm. This action provides the return bias for the handle while at the same time there is no additional pressure to maintain the link arm 19 in contact with the switch arm 5 other than the normal closed toggle position bias via the handle 15. It will be appreciated that what has been achieved is action by a torsion spring only where desired for the two operating states of the miniature circuit breaker. There is a dual function in the open position, namely toggle bias on the - Φ <3 fh -J '' ' handle and contact bias for the link arm while in the closed position there is only a single action. When tripping occurs in the closed position the link arm may thus be moved from contact with the switch arm 5 with minimum resistance.

2. 5 The invention is not limited to the embodiments hereinbefore described above. For example, it is envisaged that a stop for the handle 15 may comprise an integral part of the handle and not a latch pin as illustrated. It is also envisaged that the torsion spring may be mounted above the handle.

3. 10 The invention is not limited to the embodiments hereinbefore described but may be varied in construction and detail.