GB2031670A

GB2031670A - Commutator motor supply circuit

Info

Publication number: GB2031670A
Application number: GB7933164A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1978-09-25
Filing date: 1979-09-25
Publication date: 1980-04-23
Also published as: PL218260A1; SE7907889L; IT7925871A0; DE2841690A1; DK397179A; JPS5546892A; FR2436838A1; IT1123250B; DD146068A5; NL7907108A

Abstract

The invention relates to a driving arrangement preferably for automatic washing machines, having a commutator motor (3) supplied from a single-phase AC power supply, its speed controlled via a TRIAC (1). The iron and commutation losses occurring during low-speed operation can be reduced by using an uncontrolled, full-wave rectifier arrangement (bridge rectifier 2), connected between the output terminals (11, 12) of the TRIAC (1) and the input connections (32, 32) of the motor (3). Preferably, the TRIAC is IC-controlled. <IMAGE>

Description

SPECIFICATION Driving arrangement, for example for an automatic washing machine The invention relates to a driving arrangement which is suitable for, though not intended exclu sively for, use in an automatic washing machine.

In one driving arrangement, a commutator motor, serving to provide all the driving requirements of the washing machine, is directly connected to the output terminals of a TRIAC controlled by a triggering diode. With an assumed reduction ratio of 1:15 provided by the belt drive between the belt pulley con nected with the washing drum on the one hand and the belt pulley connected with the shaft of the driv ing motor on the other hand, the supply voltage of the motor in washing operation is reduced by the TRIAC by means of a phase gating control such that the speed of the driving motor is approximately 800 rev/min. In "centrifugal" operation in which the washed clothes are spun at very high speed, a motor speed of approximately 12000 rev/min can then be provided.

With reduced speed during washing operation a motor of this description suffers relatively high iron and commutation losses, more particularly as a result of the coils short-circuited by the brushes.

Clearly, an improvement would be obtained of these losses could be reduced using simple means whilst retaining inexpensive component parts for controlling and regulating the speed of the driving motor during washing and "centrifugal" operation.

According to the invention there is provided a driving arrangement comprising a commutator motor and a supply arrangement for supplying power from a single-phase AC power supply source to the motor, the supply arrangement comprising a TRIAC operable to control the motor speed, and an uncontrolled, full-wave rectifier arrangement connected to feed power from the output of the TRIAC to the supply input of the motor.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing which shows schematically one embodiment of the invention.

The terminals 31,32 of a single-phase commutator motor 3 provided for the drive of an automatic washing machine, having a series winding 33 in the case of the illustrated constructional example and a commutator 34, are connected to the output terminals 23, 24 of a bridge circuit 2. The bridge circuit comprises, as represented only schematically here, four bridge arms provided with simple, uncontrolled rectifiers, providing full-wave rectification.

The input terminals 21, 22 of the bridge circuit 2 are connected to the output terminals 11, 12 of a preferably IC-controlled (integrated circuit controlled) TRIAC 1, its input terminals 13, 14 being supplied from the poles R, Mp of a single-phase AC current supply.

In this way, the motor is fed by rectified current by means of the interconnected bridge rectifier arrangement, which can be constructed using sim ple means, with the result that commutation losses in the coils short-circuited by the brushes can be substantially prevented. Such simple design and the lowest output break-down capacity can be used for the IC element, advantageously provided for controlling the TRIAC without any additional triggering transformer being required which would be necessary, for example, should a semi-controlled bridge with thyristors provided in two opposite bridge arms be used in place of the uncontrolled, full-wave rectifier arrangement.

1. A driving arrangement comprising a commutator motor and a supply arrangement for supplying power from a single-phase AC power supply source to the motor, the supply arrangement comprising a TRIAC operable to control the motor speed, and an uncontrolled, full-wave rectifier arrangement connected to feed power from the output of the TRIAC to the supply input of the motor.

2. A driving arrangement according to claim 1, wherein the TRIAC is IC-controlled.

3. A driving arrangement according to claim 1 or 2, wherein the full-wave rectifier arrangement is a bridge rectifier arrangement.

4. A driving arrangement substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Driving arrangement, for example for an automatic washing machine The invention relates to a driving arrangement which is suitable for, though not intended exclu sively for, use in an automatic washing machine. In one driving arrangement, a commutator motor, serving to provide all the driving requirements of the washing machine, is directly connected to the output terminals of a TRIAC controlled by a triggering diode. With an assumed reduction ratio of 1:15 provided by the belt drive between the belt pulley con nected with the washing drum on the one hand and the belt pulley connected with the shaft of the driv ing motor on the other hand, the supply voltage of the motor in washing operation is reduced by the TRIAC by means of a phase gating control such that the speed of the driving motor is approximately 800 rev/min. In "centrifugal" operation in which the washed clothes are spun at very high speed, a motor speed of approximately 12000 rev/min can then be provided. With reduced speed during washing operation a motor of this description suffers relatively high iron and commutation losses, more particularly as a result of the coils short-circuited by the brushes. Clearly, an improvement would be obtained of these losses could be reduced using simple means whilst retaining inexpensive component parts for controlling and regulating the speed of the driving motor during washing and "centrifugal" operation. According to the invention there is provided a driving arrangement comprising a commutator motor and a supply arrangement for supplying power from a single-phase AC power supply source to the motor, the supply arrangement comprising a TRIAC operable to control the motor speed, and an uncontrolled, full-wave rectifier arrangement connected to feed power from the output of the TRIAC to the supply input of the motor. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing which shows schematically one embodiment of the invention. The terminals 31,32 of a single-phase commutator motor 3 provided for the drive of an automatic washing machine, having a series winding 33 in the case of the illustrated constructional example and a commutator 34, are connected to the output terminals 23, 24 of a bridge circuit 2. The bridge circuit comprises, as represented only schematically here, four bridge arms provided with simple, uncontrolled rectifiers, providing full-wave rectification. The input terminals 21, 22 of the bridge circuit 2 are connected to the output terminals 11, 12 of a preferably IC-controlled (integrated circuit controlled) TRIAC 1, its input terminals 13, 14 being supplied from the poles R, Mp of a single-phase AC current supply. In this way, the motor is fed by rectified current by means of the interconnected bridge rectifier arrangement, which can be constructed using sim ple means, with the result that commutation losses in the coils short-circuited by the brushes can be substantially prevented. Such simple design and the lowest output break-down capacity can be used for the IC element, advantageously provided for controlling the TRIAC without any additional triggering transformer being required which would be necessary, for example, should a semi-controlled bridge with thyristors provided in two opposite bridge arms be used in place of the uncontrolled, full-wave rectifier arrangement. CLAIMS