This application is a 35 USC 371 application of PCT/DE 01/03930 filed on Oct. 13, 2001.
1. Field of the Invention
The invention is directed to an improved overload protection for electric machines such as electric motors and generators.
2. Description of the Prior Art
Electric machines, for example electric motors, frequently contain thermal circuit breakers, which protect the electric machine from destruction or fire in the event that its movement becomes jammed or restricted. Often a suppressor choke is used for this purpose, which is comprised of two parts soldered together at a connecting point, i.e. is comprised of a soldering point, using a solder with a particular melting temperature to form an intentional breaking point. When a carbon brush or a carbon brush cable heats the suppressor choke, this solder is heated and melts at a selected melting temperature. The windings of the suppressor choke exert a certain amount of initial stress on the suppressor choke and therefore on the connecting point so that when the soldering point softens, this connection should be broken. The electric circuit of the electric machine should then be permanently broken and the electric machine should be protected from being destroyed.
Frequently, however, the initial tension is not sufficient to assure a reliable breaking of the soldering point when the suppression choke is heated.
The overload protection for electric machines according to the invention has the advantage over the prior art that an electric machine can more reliably be protected from destruction or fire in a simple manner.
In order to exert the mechanical stress on the connecting point, it is advantageous to use a sheet metal strip that is electrically connected to a connecting element of the suppression choke.
Another advantageous embodiment of the connection lug is a helical spring.
An exemplary embodiment of the invention is explained in detail herein below, with reference to the drawings, in which:
The reference numeral for the suppression choke according to the prior art will also be used for the suppression choke 1 according to the invention (
The suppression choke also has a first electrical connecting element 5 and a second electrical connecting element 6 for an electrical connection in an electrical circuit.
The second connecting element 6 of the suppression choke 1 is likewise connected electrically and mechanically to a second electrical connection lug 13. The second connection lug 13 is connected to another electrical line in the brush holder 9. It is necessary to exert a force to move the free end 14 of the second connection lug 13 toward the second connecting element 6 in order to fasten it to the second connecting element 6.
Starting from
It is also possible to use both of the connection lugs 11, 13 to exert a mechanical stress on the respective connecting points 15.
The connection lugs 11, 13 can also be helical springs.
The connecting point 15 of the connection lugs 11, 13 and the connecting elements 5, 6 assumes the function of the breaking point 7 of the suppression choke according to the prior art.
In the overload protection according to the invention, this breaking point 7 is eliminated. Instead, a connecting point 15 is used, which is also present in the prior art. In the prior art, the breaking point 7, which protrudes beyond the dimensions of the suppression choke, often causes a ground contact in the pole housing when the connecting point 7 is broken. This disadvantage is eliminated in the overload protection according to the invention.
Because there are two connecting points of connection lugs and connecting elements, it is also possible for both to be embodied in the form of connecting points to be broken in the event of an overload.
The foregoing relates to preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
100 52 220 | Oct 2000 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE01/03930 | 10/13/2001 | WO | 00 | 9/8/2003 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO02/33721 | 4/25/2002 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2491032 | Burke | Dec 1949 | A |
2804587 | Bregman | Aug 1957 | A |
4319126 | Lujic | Mar 1982 | A |
5306974 | Bates | Apr 1994 | A |
5637967 | Kim | Jun 1997 | A |
5896080 | Chen | Apr 1999 | A |
6198643 | Gray | Mar 2001 | B1 |
6348851 | Wyser et al. | Feb 2002 | B1 |
6737770 | Sunaga et al. | May 2004 | B1 |
6876533 | Ryan | Apr 2005 | B1 |
Number | Date | Country |
---|---|---|
2 125 116 | Nov 1972 | DE |
3 045 540 | Jun 1981 | DE |
968 991 | Dec 1950 | FR |
2 510 811 | Feb 1983 | FR |
Number | Date | Country | |
---|---|---|---|
20040042147 A1 | Mar 2004 | US |