1. Field of Invention
The present invention relates to an electromagnet and, more particularly, to a proportional electromagnet.
2. Related Prior Art
An electromagnet is used for turning electricity into magnetism and often used where intermittent movement is desired. The electromagnet includes a coil around a metal core which includes a bore defined in an end. The bore jeopardizes the density of the magnetism. Therefore, the magnetism is not constant in an operative stroke.
Referring to
One of the branches goes into a second air gap 56. The other branch goes into a supporting element 58 via a flange 57. Then, the magnetic circuit returns into the coil unit 51 via a second bushing 59. The bushings 52 and 59 and the air gaps 54 and 56 and the flange 57 are magnetic air gaps that exhibit a magnetic resistance about 400 to 800 times as high as magnetic metal about a same distance and area. Hence, an electromagnetic apparatus will operate inefficiently if includes many magnetic air gaps.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.
It is an objective of the present invention to provide a proportional electromagnet for providing substantially constant magnetism during an operative stroke.
To achieve the foregoing objective, the proportional electromagnet includes a cylindrical shell, first and second covers connected to two ends of the shell by riveting, a metal core inserted through an axial defined in the second cover and formed with a first section located in the shell and a second section located outside the shell, a coil unit provided between the shell and the metal core, a supporting element provided on the first section of the metal core, a bushing provided on the second section of the metal core, a copper ring provided on the first section of the metal core to improve magnetic thrust of the proportional electromagnet, a stop provided on the first section of the metal core, and a magnetic shield provided between the first section of the metal core and the coil unit to direct magnetic flux toward the supporting element and the metal core to stably drive the metal core. Other objectives, advantages and features of the present invention will be apparent from the following description referring to the attached drawings.
The present invention will be described via detailed illustration of the preferred embodiment versus prior art referring to the drawings wherein:
Referring to
The metal core 2 is inserted in the shell 1. The metal core 2 includes a first end located outside the shell 1 and a second end inserted in the shell 1 and connected to the supporting element 3. Between the shell 1 and the metal core 2 is provided the coil unit 4.
A horn-shaped bushing 21 is connected to the first end of the metal core 2 while a copper ring 22 and a stop 23 are connected to the second end of the metal core 2. Between the metal core 2 and the coil unit 4 is provided a magnetic shield 24. The metal core 2 and the coil unit 4 are made of a same magnetic material or different magnetic materials. The bushing 21 and the stop 23 are made of stainless steel that is non-magnetic. The magnetic shield 24 is made of copper. The stop 23 is used to control the shortest distance between the supporting element 3 and the metal core 2 when they are attracted to each other because of magnetic excitement.
The present invention exhibits several advantageous features over the prior art. At first, subjected to a same electromotive force (“NI”), the present invention produces a magnetic circuit to provide a larger electromagnetic force than the prior art. Referring to
Secondly, a conical surface is used instead of a conventional wedge-like surface. Therefore, the present invention can be made more easily than the prior art without jeopardizing the performance.
Thirdly, the lining 21 is directly secured to the supporting element 3 by welding instead of the conventional caps that involve more difficult fabrication.
Fourthly, the present invention exhibits less magnetic resistance than the prior art because that the coil unit 4 is in direct contact with the supporting element 3.
The present invention has been described via the detailed illustration of the preferred embodiment. Those skilled in the art can derive variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention defined in the claims.
Number | Date | Country | Kind |
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100120280 | Jun 2011 | TW | national |