Electricity: electrical systems and devices – Control circuits for electromagnetic devices – For relays or solenoids
Patent
1998-11-09
2000-06-20
Sherry, Michael J.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
For relays or solenoids
361190, 361196, 361 3, H01H 4700
Patent
active
060784911
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid relay having yoke unit which passes through the coil, at least one armature, at least one contact pair which is switched by the armature, and contact pair, switches the load circuit of the relay and whose switching time can be controlled to be offset in time with respect to that of the electromagnetic relay system wherein the contact pair is in each case switched on no-load.
2. Description of the Prior Art
When relay contacts are switched on load, they are severely stressed, primarily by the switching arc that occurs, and the large amount of heat produced can lead to welding of the contacts, or at least to undesirable material migration, to erosion and thus to a reduction in life. In order to avoid these effects, so-called hybrid relays are used which, in the manner stated initially, use an electronic switch in addition to the mechanical relay contacts. This electronic switch is operated offset in time and thus absorbs the load peaks during switching on and off; the relay contacts are in this case switched "dry" and, in consequence, can achieve a long life at low cost. Such hybrid circuits have been disclosed, for example, in DE 37 01 838 A1 or U.S. Pat. No. 4,772,809. Depending on the circumstances, relay contacts are connected either in parallel or in series with the power semiconductor in these circuits. In the former case, the power semiconductor is first switched on and then the relay contact is closed so that, in continuous operation, the load flows via the relay contact while the semiconductor need then carry only a relatively small proportion of the current or can be switched off entirely. The sequence during switching off is the reverse of this. In the second case, that is to say in the case of the series circuit, the relay contact is first closed and then the power semiconductor is switched on or, during switching off, the power semiconductor is switched off before the contacts are opened, with no current flowing through them. In this second case, the load current also flows continuously via the power semiconductor so that it also has to cope with a considerable heat loss. This series circuit is significant, for example, if two circuits have to be closed or opened precisely at the same time on a double relay or a polarity reversal relay.
In the case of conventional hybrid relays and hybrid circuits, conventionally designed electromagnet systems and standard semiconductors are connected using a conventional circuit technique. As a rule, this means that the two systems are arranged on a common printed circuit board, with a corresponding space requirement. In this case, the heat losses from the semiconductor also have to be dissipated in a conventional manner via heat sinks.
An object of the present invention, therefore, is to provide a hybrid relay of the type mentioned initially which has a compact design and which also allows good and simple heat dissipation for the power semiconductor while using as few individual parts as possible.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved in the case of a hybrid relay of the type mentioned initially in that the power semiconductor is in thermal contact with the core yoke unit of the electromagnetic relay system.
Various techniques have admittedly already been proposed for accommodating a semiconductor, or a semiconductor circuit, in the housing of an electromagnetic relay (EP 0484 587 B1). Moreover, until now, this has always been done independently of the magnet system and without any circuitry link to the contacts. In contrast, in the relay according to the present invention, the power semiconductor is mounted directly on the core yoke of the electromagnetic relay which, owing to its relatively large cross section, quickly dissipates the heat produced in the transistor; partially via its own large surface area and partially via the core winding. In this case, the magnetic circuit of the relay also carries out the func
REFERENCES:
patent: 4772809 (1988-09-01), Koga et al.
patent: 4956738 (1990-09-01), Defosse et al.
patent: 5283706 (1994-02-01), Lillemo et al.
Kern Josef
Samray Bican
Sherry Michael J.
Siemens Aktiengesellschaft
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