DE1011967B - Device for switching a single-phase motor with starting and operating winding - Google Patents

Description

The invention relates to a switching device for a single-phase motor with starting and operating winding, namely a two-way switching device that controls the motor as a function of both the load how the ambient temperature can switch.

The connection of the starting and operating windings is preferred in such a switching device controlled by an elastic element which, depending on the current flowing through it, expand or can contract. The dependence of the switching device on the ambient temperature is thereby causes a shunt circuit to be placed parallel to the expandable element, which depending on the ambient temperature is closed or open. When this shunt is closed, it branches off part of the operating current, so that not the full current through the expandable element flows. But if it opens when the ambient temperature rises, the stretchable element must den take over all electricity. It will expand accordingly, and so will the switching device switch on or switch off the motor.

In the known devices, the mentioned shunt circuit is not only during normal Operation, but also closed when the motor is starting. However, this is not desirable because the starting winding is switched off as quickly and safely as possible after the motor has started up and the shunt should therefore be open during startup so that the ductile Element carries the full current.

The switching device is therefore designed according to the invention so that the shunt circuit, which in the normal Operation only switched on or off by a switch that depends on the ambient temperature is electrically disconnected when the motor starts up and only when the circuit is opened the start winding is closed. This ensures that the entire Current flows solely through the elastic element, so that it is more sensitive and the starting winding switches off faster and safer. In particular, the starting winding is also switched off with certainty, if the switching device is already somewhat worn through use.

Further details and advantages of the invention emerge from the following description, in an embodiment is explained in more detail with reference to the drawings.

In the drawings shows

Fig. 1 is a partially schematic view of the switch in the starting position,

Fig. 2, however, such with an open starting circuit.

Device for switching a

Single-phase motor with starter

and operational winding

Applicant:

General Motors Corporation,
Detroit, me. (V. St. A.)

Representative: Dr. W. Müller-Bore, patent attorney,
Braunschweig, Am Bürgerpark 8

Claimed priority:

V. St. v. America July 13, 1951

Harry Carlton Swan, Dayton, Ohio (V. St. Α.),
has been named as the inventor

A rigid frame 20 carries a leaf spring 21, and two resilient switching tongues 22 and 23 are on it fastened by a rivet 24. At the free end of the tongue 22 are two contacts 25, 26 opposite one another. Contact 25 can cooperate with an insulated contact 27 on frame 20, which is connected to the starting winding 30 of the motor is in conductive connection. The second contact 26 can be with another isolated contact 28 on the frame 20 come into engagement. The tongue 23 has a single contact 39.

The leaf spring 21 carries an electrically conductive spring element 35, which it normally does in the opposite direction endeavors to rotate clockwise, as can be seen from FIG. This jump member 35 also forms the Stop for two dead center spring fingers 36, 47 on the associated contact tongues 22, 23. The finger 36 is either attached to tongue 23 or worked out of it so that both form a whole; be free end rests in a V-shaped notch 37 which is formed in the end of the jump member 35. if if the notch 37 is on one side of the contact tongue 23, as in FIG. 1, the finger presses 36 through the tongue so that the contact 39 at its free end with the associated isolated contact 40 on the frame 20 comes into contact. But if the notch37 is on the opposite side of the tongue 23 (Fig. 2), the pressure effect of the finger 36 is reversed, the contacts 39 and 40 open thus interrupting the current through the main or service winding 45 of the motor.

709 587/330

1 Oil

The tongue 22 has a similar resilient finger 47 which rests in the notch 37 and the relative location the notch 37 on one side or the other of the tongue 22 determines its position in a similar manner as with tongue 23, as can easily be seen. If there is no other action on the jump link 35 If the spring action of the leaf spring 21 were to exist, the parts would remain in the position of FIG.

To close contacts 25 and 39, i. H. to be brought together with the associated fixed contacts 27 and 40, the jump member 35 must be rotated clockwise. It does this through the Thermal expansion member 50, a wire made of electrically conductive material that is mechanically connected to a End on jump member 35 and with the other on an adjustable insulated connector 51 of the Frame is attached so that the hot wire 50 with both contact tongues over the jump member 35 in Is connected in series. The connection piece 51 is adjustable for the purpose of the tensile stress in the Change hot wire 50; as a result, if no current flows through it, it normally holds the Spring member 35 against the spring 21 in a position in which the resilient contact tongues belong together Keep contact pairs 25, 27 and 39, 40 closed (Fig. 1).

The wire 50 is not influenced by the ambient temperature, but it elongates and shortens depending on the current flowing through it. The connection member 51 to which the hot wire is attached is, is connected to one pole of a power source, which is on the other hand connected to the starting and operating winding of the electric motor. The circuit is completed by the movable contact tongues 22, 23, the electrically conductive snap link 35 and the hot wire 50. When the circuit is closed to start the engine, it will the strong initial current surge caused by both motor windings 30 and 45 and the associated switching blades 22 and 23 flows, also passed through the expandable member 50, which then elongates. The engine starts up during this thermal expansion period. The expansion of the hot wire 50 enables the spring 21 to throw the spring member 35 counterclockwise, during the Engine reaches its actual operating speed and after the normal amount of time has elapsed is, the hot wire 50 has stretched so far that the jump member 35 over the dead center position for the Spring finger 47 can tilt away. The spring finger 47 thus presses the tongue 22 into the opposite one Direction so that it jumps around and that formed by the contacts 25, 27 and the starting winding 30 Circuit interrupts and the circuit through the upper contacts 26, 28 closes.

The circuit of the operating winding is still closed by the tongue 23 and the contacts 39, 40 held to keep the engine running.

During normal running, the current flowing through the heat expandable element 50 does not become any further Cause elongation of this element; the spring 21 is not yet over the spring element 35 let the dead center position for the tongue spring catcher 36 tilt. But if the motor is overloaded or a short circuit occurs, the current in the hot wire 50 exceeds its normal value and the wire will lengthen again and allow the spring 21 a further pivoting of the spring link 35, until the tongue 23 separates the contacts 39 and 40 and stops the motor. The hot wire 50 serves as overload protection for the electric motor or another load circuit.

A protection against increase in the ambient temperature; temperature is achieved by a flexible bimetallic strip 60 commanded; one end of which is fixed in an insulating socket on the frame 20 and electrically connected to a resistor 61, which in turn is connected to the fixed contact 28 in connection. That the free end of the strip 60 carries a contact 62; this is usually with a fixed contact 63 in engagement, which sits isolated on the frame 20 and is electrically connected to the connector 51. at The bimetallic strip maintains normal temperature its contact 62 in engagement with the fixed contact 63, but at a set value of the ambient ν temperature it bends and thus interrupts .. the current through the upper contacts26,28 of the tongue 22 for the start winding. This circuit is in parallel with the hot wire 50; during normal running it of the motor, it carries a fixed part of the total current consumed by the motor, while (ilen Rest of the hot wire 50 takes up. The ratio of the currents in the two branches of the circuit wjjd determined by resistor 61. Therefore, if the bimetal strip in response to an excessive If the ambient temperature increases its contacts 62, 63 separates, the hot wire 50 receives the whole Motor current; it then expands further, so that the spring 21 swings out the spring element 35 far enough leaves to bring the tongue 23 to tip over. But with this the operating current circuit becomes interrupted and the motor stopped.

The embodiment of the invention disclosed here represents an example of a preferred form, but of course could be within the scope of the claims other shapes can also be chosen.

Claims (6)

Patent claims: 1. Device for switching a single-phase motor with starter and operating winding, consisting of a control switch with overflow release, Thermal release and contacts for switching the starting and operating circuit on and off, caused by the thermal expansion of a current-carrying switching element, for example a hot wire, are operated in the the heat release takes place depending on the ambient temperature in that a shunt circle lying parallel to said elastic element at a certain one Ambient temperature opened and thus the current in this element increased and its expansion is enlarged, characterized in that the shunt circuit, which in normal operation only by a switch (60, 62, 63) controlled by the ambient temperature can be switched off, is electrically disconnected while the motor is starting and only when Opening the circuit (30) of the starting winding is closed, so that during the start-up time the entire current flows through the stretchable element (50) alone. 2. Device according to claim 1, wherein the control switch two each in series with the stretchable Switch element has contact tongues whose position is determined by the force of a Spring and the tensile force of the stretchable element 1 Oil are regulated, characterized in that the spring (21) both the tongues (22, 23) and leaf springs are formed and fastened together on the frame (20) and the spring (21) is rigid is connected to a jump member (35) by means of a V-shaped notch (37) in known per se Way depending on its position relative to the two tongues via resilient fingers (36, 47) the tongues (22, 23) in the on or off position presses. ίο 3. Device according to claims 1 and 2, characterized in that one of the tongues (22) has two contacts (25, 26) and depending on the relationship between the spring force and the tensile force of the heat expandable element (50) either the contact (27) of the starting circuit (30) and thus the entire starting current through the heat expandable element (50) lets flow or touches the opposite contact (28) after the motor has started up, whereby the current is branched in such a way that the one current component via the contacts (40,39) of the second tongue (23) through the heat expandable element (50) and the other current portion over the the switch causing the heat release depending on the ambient temperature (60 62,63) flows. 4. Device according to claims 1 to 3, characterized in that the heat release causing switch (60, 62, 63) is combined with the rest of the switch in one housing. 5. Device according to one or more of the preceding claims, characterized in that that the second tongue (23) with its contact (39) only then moves away from the contact (40) of the motor winding circuit (45) lifts off and thus interrupts the operating current of the motor after the contacts (62, 63) of the heat-sensitive switch (60) are separated, i.e. H. all current flows through the heat expandable element (50). 6. Device according to one or more of the preceding claims, characterized in that that the responsive to the ambient temperature switch (60, 62, 63) in series with a resistor (61). Considered publications:
British Patent No. 591 634. 1 sheet of drawings © 709 587/330 7.57