This invention relates to a device that allows output shaft to perform axial motion. In particular, it relates to a manual switch-off device for a permanent magnet switch operating mechanism. Certainly, it also can be used for some other similar occasions.
The existing power switches use electromagnetic operating mechanism or spring operating mechanism to perform switch-off and switch-on actions. The electromagnetic operating mechanism has deficiencies in that it requires additional mechanical locking device, and has complex structure, high failure rate, high noise level and short service life. The spring operating mechanism requires being driven by a motor and locked in mechanical mode, with complex structure, heavy weight, slow movement, high noise level and high failure rate. In addition, a permanent magnet monostable operating mechanism has been developed in recent years, which has a more complex structure than a bistable one, especially the manual switch-off device of which still basically adopts conventional releasing principle, with large number of parts and complex structure that cause frequent malfunction of the locking part. The manual switch-off devices of the above operating mechanisms all operate with the normal actions of the mechanism, and has short service life due to frequent operations. Another CN patent owned by the Applicant, Patent No. ZL98220417.5 (Title: a permanent magnet operation mechanism for vacuum switch) discloses an operating mechanism that uses electromagnetic force to perform switch-off/switch-on and uses magnetic force of a permanent magnet to perform locking operation. Such an operating mechanism has simple structure and low failure rate. However, the operating mechanism has deficiencies that due to extremely large attraction force of the permanent magnet, once the electromagnet coil and the trip circuit have malfunction, it may be difficult to perform emergency switch-off manually, and the manual switch-off mechanism based on common lever principle cannot ensure stable switch-off speed. The essence of the permanent magnet operating mechanism is to allow an output shaft to perform axial motion, so as to perform switch-off/switch-on actions. However, up to now there has not been a manual switch-off device that is simple, reliable and that complies with the technical requirements in the field.
The object of the present invention is to provide a manual switch-off device for a permanent magnet switch operating mechanism that has simple structure and low failure rate. The device allows an output shaft of the permanent magnet mechanism to perform axial motion and to lock bilaterally, and the device complies with technical requirements for manual switch-off power switch.
To achieve the above objects, the present invention provides the following technical solutions:
A manual switch-off device for a permanent magnet switch operating mechanism of the present invention includes a large shoe plate and a small shoe plate fixed onto a base plate in parallel, a transmission shaft rotatably installed onto the large shoe plate and the small shoe plate, an eccentric wheel fixed onto the transmission shaft between the large shoe plate and the small shoe plate, and an output shaft installed onto the base plate in parallel with the large shoe plate and the small shoe plate. One end of the output shaft has an end cap. The large shoe plate has an open slot. The eccentric wheel has a spring column fixed thereon, and the spring column connects to one end of a manual switch-off spring through the open slot. The other end of the manual switch-off spring hooks to a spring mount point on the large shoe plate. The spring mount point is located above central extension line of the spring column and the transmission shaft under switch-on state, to satisfy the requirement of the spring column passing the dead point when switching on.
The end cap is in hinge joint with the output shaft through a connecting pin.
The eccentric wheel is shaped in disk, and connects to the transmission shaft through a fixed point on the center of the disk.
The eccentric wheel is an elliptic wheel or other non-linear curve wheel.
The transmission shaft has a single direction switch-off handle.
The eccentric wheel and the transmission shaft are so connected, when manually rotating the transmission shaft towards switch-off direction, the eccentric wheel rotates along the transmission shaft, so that the tangency point of the eccentric wheel and the end cap moves towards switch-off direction, to lift up the end cap, and thus to pull the output shaft to one side, to allow the output shaft to perform axial motion. In addition, the operating mechanism has the following advantages:
As shown in
Application of the present invention will be described in detail below with
A manual switch-off mechanism for a permanent magnet switch operating mechanism of the present invention is installed on the end-cap 15 of the above-described operating mechanism. When the operating mechanism operates normally, the manual switch-off device does not act. The manual switch-off spring 10 locks the transmission shaft 8 by using the principle of passing “dead point”, to stop the transmission shaft 8 to rotate at discretion. Here the operating mechanism of the switch performs switch-on/switch-off by means of the magnetic force of the electromagnetic coil 5. When the electromagnetic coil 5 has malfunction and cannot perform switch-off, one only needs to pull a handle 16 on the transmission shaft 8 to rotate the transmission shaft 8 to a certain angle, upon the mount point of the manual switch-off spring 10 passes “dead point” (extension line connecting the mount point and the axes of the transmission shaft 8), with the pull of the manual switch-off spring 10, the eccentric wheel 14 rotates quickly to push the end cap 9 and the output shaft to rapidly move, so as to achieve quick manual switch-off. Upon the electromagnetic coil 5 resumes normal operation, re-use the electromagnetic coil to perform switch-on, the end cap 9 presses the eccentric wheel 14 to rotate in a direction opposite to the one for switching-off, and the spring mount point on the eccentric wheel 14 pulls the spring. When the spring mount point on the eccentric wheel 14 passes “dead point”, the eccentric wheel 14 rotates a stable angle under the spring force to reach a stable point, and store spring energy for the next manual switch-off. Upon the eccentric wheel 14 reaches the stable point, due to the stable angle, the manual switch-off device does not act when in normal operation of switch-on/switch-off. After switching on, the manual switch-off spring will not pose counterforce against the attraction force of the permanent magnet, so as to ensure that the pressure on the switch contact will not decrease.
The eccentric wheel 14 changes the ratio between power arm and resisting arm with the rotation angle of the eccentric wheel 14. When initiating manual switch-off, the ratio of the arms is very big, the output shaft 2 overcomes resistance from the permanent magnet with a small force, and moves towards switch-off direction. With increasing rotating angle of the eccentric wheel 14, the ratio of the arms gradually reduces, and the moving speed of the output shaft 2 increases constantly under the joint effect of external force and the manual switch-off spring force, to achieve rapid switch-off. Upon the manual switch-off handle rotates to a certain angle, it mainly uses the manual switch-off spring 10 to perform switch-off, and thus to avoid instability caused by human factors on the switch-off speed.
The shape of the eccentric wheel 14 decides changes of the moving speed of the output shaft 2. In practice, the eccentric wheel 14 can be designed in a shape of circular, elliptical or other non-linear curve.
Certainly, the application of the present invention is not limited as discussed above. The present invention can be used in any similar devices that require driving the output shaft for axial motion.
Number | Date | Country | Kind |
---|---|---|---|
2005 1 0042050 | Jan 2005 | CN | national |
Number | Name | Date | Kind |
---|---|---|---|
3254660 | Ray | Jun 1966 | A |
5372351 | Oliver | Dec 1994 | A |
Number | Date | Country |
---|---|---|
98220417.5 | Sep 1999 | CN |
Number | Date | Country | |
---|---|---|---|
20060162194 A1 | Jul 2006 | US |