Spring drive cam for a spring drive of a circuit breaker

Abstract

Provided is a spring drive cam for a spring drive of a circuit breaker including a disc-like shape configured for rotating around a rotation axis in the spring drive, whereby the disc-like shape comprises a radius (R) that changes depending on an angle (α) of the radius (R) relative to a base angle (α0), and whereby a rate (dR/dα) defined by a change of the radius (R) per change of the angle (α) is ≤0.3 mm/°.

Claims

1. A spring drive cam for a spring drive of a circuit breaker comprising a flat cam profile configured to rotate around a rotation axis in the spring drive, wherein the flat cam profile comprises a radius (R) being the distance between a point of the cam profile and its axis of rotation that changes depending on an angle (α) of rotation relative to a base angle (α0) in an initial position of the cam, and a rate (dR/dα) defined by a change of the radius (R) per change of the angle (α) is ≤0.3 mm/° for the radius (R)≥82 mm and ≤125 mm and the angle (a)≥95° and ≤210°, and wherein the spring drive cam is attached to a closing spring.

2. The spring drive cam according to claim 1, wherein the rate (dR/dα) is <0.28 mm/°, 0.28 mm/° and/or constant.

3. The spring drive cam according to claim 1, wherein, for the rate (dR/dα)≤0.28 mm/°, the radius (R) is ≥92 mm and ≤115 mm.

4. The spring drive cam according to claim 1, wherein, for the rate (dR/dα)≤0.28 mm/°, the angle (α) is ≥105° and ≤200°.

5. The spring drive cam according to claim 1, wherein, for any rate (dR/dα), the radius (R) is ≥40 and ≤130 mm.

6. The spring drive cam according to claim 1, wherein, for the radius (R)<82 mm and the angle (α)<95°, the rate (dR/dα) is >0.3 mm/or, for the radius (R)<92 mm and the angle (α)<95°, the rate (dR/dα) is greater than 0.3 mm/° and/or, for the radius (R)>125 mm and the angle (α)>210° the rate (dR/dα) is ≤0.3 mm/° or, for the radius (R)>115 mm and the angle (α)>200° the rate (dR/dα) is <0.3 mm/°.

7. The spring drive comprising the spring drive cam according to claim 1, an opening spring configured to open the circuit breaker and a closing spring configured to close the circuit breaker and reload-ing the opening spring, wherein the opening spring and the closing spring are in rotational contact with the spring drive cam.

8. The spring drive according to claim 7, wherein the rate (dR/dα)≤0.3 mm/° yields a rotational speed of the cam (3) of ≤4600°/s.

9. The circuit breaker comprising the spring drive according to claim 7 and a couple of conducting terminals, wherein the spring drive is configured to move at least one of the conducting terminals for electrically connecting and disconnecting the conducting terminals.

10. The circuit breaker according to claim 9, wherein one of the conducting terminals is provided as contact plug and the other of the conducting terminals is provided as corresponding contact tulip, whereby the conducting terminals are arranged in coaxial arrangement and at least one of the conducting terminals is arranged movable relative to the other of the of the conducting terminals.

11. The spring drive cam according to claim 1, wherein the closing spring is attached to the spring drive cam at a rotational axis of the spring drive cam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.

(2) In the drawings:

(3) FIG. 1 shows a spring drive of a high voltage circuit breaker comprising a spring drive cam according to a preferred implementation in a schematically view,

(4) FIG. 2 shows the spring drive cam of FIG. 1 in a schematically top view, and

(5) FIGS. 3a-3b show cam rate/radius and cam rate/angle diagrams of the spring drive cam of FIG. 1.

DETAILED DESCRIPTION OF EXEMPLARY IMPLEMENTATIONS

(6) FIG. 1 shows in a schematically view a spring drive 1 of a high voltage circuit breaker 2, only indicated, comprising a spring drive cam 3 according to a preferred implementation. FIG. 2 shows the spring drive cam 3 in an enlarged view.

(7) The circuit breaker 2 comprises a couple of conducting terminals 4, 5 as arcing contacts, only schematically depicted, which are actuated by an interrupter 6 of the spring drive 1, indicated by a dotted line, for interrupting a current flowing between the conducting terminals 4, 5. One of the conducting terminals 4 is provided as contact plug and the other of the conducting terminals 5 is provided as corresponding contact tulip. The conducting terminals 4, 5 respectively the contact plug and the contact tulip are arranged in coaxial arrangement. The interrupter 6 moves at least one of the conducting terminals 4, 5 relative to the other of the of the conducting terminals 4, 5 in axial direction for electrically disconnecting respectively connecting the conducting terminals 4, 5.

(8) The spring drive 1 further comprises an opening spring 7 and a closing spring 8 for opening respectively closing the circuit breaker 2. An interaction between opening spring 7 and closing spring 8 is realized by the cam 3. Specifically, during close operation of the spring drive 1, a roller 9 interacts with the cam 3 and transmits the motion through a linkage 10 of the spring drive 1 to the interrupter 6. A first open operation is followed by a close operation, during which the opening spring 7 is charged again so that the spring drive 2 becomes able to perform a second open operation.

(9) Thereby, the profile of the cam 3 influences a closing speed and velocity of the spring drive 1. If the speed reaches a critical level, significant bouncing of the contact tulip occurs, which could lead to mechanical failures of the contact tulip and thus of the circuit breaker 2.

(10) In order to ensure that the closing speed does not exceed critical level, the disc-like shaped spring drive cam 3 as depicted in greater detail level in FIG. 2 comprises a radius R that changes depending on an angle α of the radius R relative to a base angle α.sub.0 if the cam 3 rotates around a rotation axis 10, whereby a rate dR/dα defined by a change of the radius R per change of the angle α is 0.28 mm/°. The base angle α.sub.0 is the position of the cam in a base position where conducting terminals 4, 5 are electrically conducting and, as can be seen from FIG. 2, extends in horizontal direction.

(11) Thereby, the rate dR/dα is constant or at least nearly constant for the radius R in the range between 92 mm and 115 mm, as can be seen from FIG. 3a, and for the angle α in the range between 105° and 200°, as can be seen from FIG. 3a. For smaller and greater radius R and angle α the rate dR/dα may generally have an arbitrary value, whereby, as can be seen from FIGS. 3a and 3b, the rate dR/dα is higher than 0.28 mm/° for radius R and angle α smaller than 92 mm respectively 105° and lower than 0.28 mm/° for radius R and angle α greater than 115 mm respectively 200°. Generally, the radius R of the spring drive cam 3 is ≥40 and ≤130 mm for any rate dR/dα.

(12) The following table shows the angle α in respect to the radius R between 0° and 290° of the cam 3:

(13) TABLE-US-00001 Angle/° R/mm  0 45.63  5 48.55  10 51.46  15 54.45  20 57.45  25 60.32  30 63.06  35 65.68  40 68.18  45 70.57  50 72.85  55 75.02  60 77.10  65 79.07  70 80.96  75 82.76  80 84.47  85 86.11  90 87.67  95 89.17 100 90.60 105 91.97 110 93.29 115 94.52 120 95.57 125 96.61 130 97.66 135 98.72 140 99.78 145 100.9 150 101.9 155 103.0 160 104.1 165 105.2 170 106.4 175 107.5 180 108.7 185 109.9 190 111.1 195 112.3 200 113.6 205 114.8 210 116.1 215 117.3 220 118.6 225 119.8 230 121.1 235 122.3 240 123.5 245 124.7 250 125.8 255 126.6 260 127.2 265 127.6 270 128.0 275 128.2 280 127.7 285 126.5 290 124.1

(14) With the proposed rate dR/dα of ≤0.28 mm/° at least in the range between 92 mm and 115 mm and between 105° and 200° the cam 3 yields in low closing velocity during the impact of the circuit breaker's 2 arcing contact.

(15) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed implementations. Other variations to be disclosed implementations can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.

REFERENCE SIGNS LIST

(16) 1 spring drive 2 circuit breaker 3 spring drive cam 4 conducting terminal 5 conducting terminal 6 interrupter 7 opening spring 8 closing spring 9 roller 10 linkage 11 rotation axis α angle α.sub.0 base angle R radius dR/dα rate