DE4033737A1 - Starting and operating circuit for single phase electromotor - includes first capacitor for starting only and second capacitor with another capacitance only for motor running - Google Patents

Abstract

The two capacitors (1,2) are connected in parallel, and both are connected in series for the supply phase (3) of the electric motor (4). An ON and OFF switching device (5) is provided for the starting capacitor (1). The switching device is connected directly to the supply phase of the starting and running capacitors and is fed with the same voltage lying at the running capacitor (2). The starting and running capacitors are accommodated in the same housing which can be connected to the electric motor (4). The switching device (5) is connected in series with the starting capacitor (1). USE/ADVANTAGE - Integral component and connection of two cables only. Automatic motor starting system.

Description

The present invention relates to a starting and Operating device for single-phase electric motors.

It is known that single-phase electric motors, for example to drive office machines or Power tools or for household appliances, also the Use the effect of the magnetic rotating field, however special technical measures and auxiliary devices need to self-start in the loaded state too allow.

Essentially, all measures are based on Self-starting of single-phase motors on creation of a rotating field with the motor stopped using a Starting auxiliary winding Ap, the characteristics of which allow one strongly out of phase with the main river to generate magnetic flux. The auxiliary winding is around Arranged 90 ° to the main winding Aa and after successful startup switched off.

The phase shift between the current of the Auxiliary circle and that of the main circle is predominant achieved by placing a capacitor in the circuit of the Auxiliary winding is switched, creating a circle arises, one that leads the tension phase-shifted current results. Except for the above single-phase induction motors, are often all those induction motors included in this group,  which are provided with two windings, one of the Windings - also referred to here as auxiliary windings - A capacitor is switched and both Main winding as well as the auxiliary winding continuously stay on, both during the Startup as well as in normal operation. Have these engines however, usually not a high starting torque because of the value the capacity to be provided in the auxiliary winding for high Starting torque would be excessively high to be flawless Function at normal operating speeds too to reach. For good functional properties (without Restriction e.g. B. the dimensions or the Insulation classes) with good tarnishing properties of the single phase motor with capacity auxiliary phase combine, two capacitors are often in the Auxiliary circuit switched, one of which after the Startup is switched off.

The prior art therefore provides for such engines the use of three different elements before and Although: The starting capacitor, the operating capacitor and a changer or an automatic starter switch. The latter is implemented in different ways. A The solution is to open a centrifugal switch the shaft in front, with the switch opening as soon as the Engine reaches a certain speed and thereby the Starting capacitor switches off.

Another solution is a delayed relay interpose, which after a few seconds Contact of the starter circuit opens.

Another solution, which does not work automatically, consists of the main switch with an auxiliary contact to provide and compel the consumer to do so  Contact closed for a few seconds when starting hold; however, this solution is dangerous if the Contact is not opened in the specified time because of the motor could be damaged.

The other two automatic solutions are sufficiently effective, but require the installation of three various elements and in addition all electrical Connections of the same, which complicates this system and becomes complex and maintenance-intensive.

The purpose of this invention is therefore that to eliminate the above-mentioned shortcomings. The Invention as defined by the claims is characterized, solves the problem with a start-up and operating circuit for single-phase electric motors that includes: two capacitors with different capacities, one for startup and one for operation, which are connected in parallel to each other and both in series to the supply phase of the electric motor are switched, as well as an on and off device of the starting capacitor, the inputs and Switch-off device directly to the supply phase named capacitors connected and with the same Power is supplied on the above Operating capacitor is present. Also mentioned are A and switch-off device and the capacitors in the same Housing housed that on the mentioned electric motor can be connected.

One of the advantages of this invention is essential in that with the installation of a single one-piece component and the connection of only two Cables, an automatic engine starting system on extreme is realized economically.  

The invention is further explained in detail with the With the help of drawings, which are purely exemplary and not represent a limiting embodiment.

Figs. 1 and 2 show schematically the circuit according to the present invention.

FIG. 3 shows schematically a practical embodiment of the circuit according to Fig. 1 and 2.

According to the invention and with reference to the above figures, the starting and operating circuit for single-phase electric motors consequently comprises a first starting capacitor 1 which is connected in parallel with a second operating capacitor 2 of the single-phase electric motor 4 . The two capacitors are connected in parallel to one another and both are connected in series to the supply phase 3 of the electric motor 4 . Is directly connected the electric motor to the supply phase 3 and connected to the starting capacitor in series 1 further comprising an in- and off switch 5 of the starting capacitor. 1 The device 5 therefore has the same supply voltage for the capacitors 1 (start-up) and 2 (operation).

All three components are housed in a single housing 6 , which can be connected to the electric motor 4 . In this way, the electrical connection between the three components, ie the starting capacitor 1 , the operating capacitor 2 and the device 5 , and between these components and the electric motor 4 is possible by only two cables and the operation is ensured by the same voltage as that on the electric motor 4 is present.

As can be seen from FIG. 2, the switch-on and switch-off device 5 of the starting capacitor 1 comprises a rectifier 7 , which is connected in the input to the supply phase 3 of the electric motor 4 and in the output to a delay circuit or filter 8 . The delay circuit is in fact able to delay the opening of the changeover contact 9 - as a rule a relay - which switches off the starting capacitor at the desired point in time by appropriately designing the capacitance, ie when the motor has already overcome the starting phase.

For proper functioning, a further delay in the opening of the relay 9 is provided by connecting a further capacitor 12 with a suitable capacitance in parallel, which charges during the operation of the electric motor 4 and maintains the charging voltage. If the motor should stop for external load or other reasons, the capacitor 12 discharges onto the excitation coil of the relay 9 and thus delays the opening. In this way, the motor 4 has sufficient time to stop completely and the operating capacitor 2 discharges directly onto the windings of the electric motor 4 without stressing the contacts of the relay 9 , which would otherwise be damaged.

To further protect the changer 9 , a discharge resistor 11 is connected in parallel with the starting capacitor 1 . As soon as the device 5 opens the circuit in which the starting capacitor 1 is located, the latter remains well charged, but immediately discharges to the resistor 11 . In this way, the starting resistor 1 cannot discharge onto the contacts of the changer 9 , which are thus additionally protected.

A long service life of the switch-on and switch-off device 5 is therefore guaranteed, since the measures mentioned never result in an energy transfer to the changer 9 .

There are numerous changes to the invention so conceived and variants conceivable, all in the area of Invention fall. Furthermore, all items be replaced by technically equivalent elements.

In practice there are of course changes and / or Improvements possible in any case in the area of claims fall.

Claims (6)

1. Starting and operating circuit for single-phase electric motors, which comprises the following: two capacitors ( 1 , 2 ) of different capacitance, including a first capacitor ( 1 ) for starting and a second capacitor ( 2 ) for operation, which are connected in parallel to one another and both to the supply phase ( 3 ) of the electric motor ( 4 ) are connected in series and an on and off device ( 5 ) of the starter capacitor ( 1 ), characterized in that said on and off device ( 5 ) is directly connected to the supply phase ( 3 ) - And operating capacitors ( 1 , 2 ) is connected and fed with the same voltage that is present at the operating capacitor ( 2 )) and characterized in that said switching on and off device ( 5 ) and said starting and operating capacitors ( 1 , 2 ) in same housing ( 6 ) are housed, which can be connected to said electric motor ( 4 ). 2. A circuit according to claim 1, characterized in that said switch-on and switch-off device ( 5 ) is connected in series with the starting capacitor ( 2 ). 3. A circuit according to claim 1, characterized in that said switch-on and switch-off device ( 5 ) comprises a rectifier ( 7 ) which in the input to the supply phase ( 3 ) of the electric motor ( 4 ) and in the output to a delay circuit or a filter ( 8 ) is connected, which in turn is connected to a changeover contact ( 9 ) which is connected to the supply conductor ( 10 ) of the starting capacitor ( 1 ). 4. A circuit according to claim 1, characterized in that a resistor ( 11 ) is connected in parallel with the starting capacitor ( 1 ). 5. A circuit according to claim 4, characterized in that a capacitor ( 12 ) is connected in parallel to said changer ( 9 ). 6. Circuit according to the preceding claims and after the descriptions and explanations related to the enclosed figures and for the specified ones Purposes.