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Laundry machine

a technology for washing machines and washing machines, applied in washing machines, washing machines, transmission systems, etc., can solve the problems of fixed mains-frequency pump motors, low starting torque, and easy blockage of pumps, and achieve the effect of reducing the effect of ventilation

Inactive Publication Date: 2004-05-06
FISHER & PAYKEL APPLIANCES LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a laundry machine with drain pump control, power supply, motor drive, and motor braking system that overcomes the disadvantages of existing methods. The invention includes a method of operating a drain pump in a laundry washing machine during the drain phase of the wash cycle to reduce pump blockages, a method of braking a top loading laundry washing machine spin tub, a method of powering on and off a laundry washing machine, and an optocoupler drive circuit for the high side of a totem pole power transistor pair in a bridge circuit for commutating a motor. The invention also includes a laundry washing machine including a wash bowl drain pump driven by a variable speed motor which in turn is driven by a variable frequency pulse width modulated inverter, and the pump motor frequency is decreased at low bowl water levels to reduce the effects of ventilation.

Problems solved by technology

There are numerous disadvantages of a fixed mains-frequency pump motor.
These are: (a) the starting torque is typically low, making the pump susceptible to being blocked, (b) separate pump designs are needed for countries having differing mains voltage and frequency, (c) the noise level during "ventilation" is high, particularly when running at a supply frequency of 60 Hz, (d) the torque varies with the mains voltage and (e) there is no feedback to indicate if the pump is faulty.
Home appliances, however, do not have the space available to utilise large flow passages.
Unfortunately this pump has the disadvantage that it can still become blocked by bundles of fibres that become twisted "ropes" in the centre of the vortex.
In the first power to the washer is isolated using an expensive mains rated switch which de-energises it and makes power consumption negligible.
These methods have the respective disadvantages that either a high current and / or voltage rated switch is required or power is consumed unnecessarily when the laundry machine is not in use.
When transistor Q2 switches off, noise is generated which tends to pull the optocoupler off.
The disadvantage of this conventional optocoupler drive design is that high quality and therefore high cost devices are required.
This technique has the disadvantage that relatively high power resistors are required and these add to the cost of the laundry machine.

Method used

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Examples

Experimental program
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Effect test

first embodiment

[0035] In this invention there is provided a method of drain pump motor control that will flush through bundles of fibres before they become large enough to jam the pump. Typically the pump motor will be an ac induction motor which may be of the shaded pole type. FIG. 1 shows the plan view of a laundry machine sludge pump, with the impeller 1 having two, backwardly inclined vanes 2, 3, with large clearances, especially to the cutwater 4. FIG. 2a shows a perspective view of sludge impeller 1. An alternative vortex impeller 5 (FIG. 2b) may be used to reduce pump noise. It has vane recessed into the impeller.

[0036] The method of operation involves stopping the pump very quickly for a short period of time every few seconds. The sudden stop of the pump means that there is no more energy put into the vortex, and the momentum of the water flowing down the discharge pipe sucks the vortex and any fibres entrapped in the vortex out the pump exit. The pump is started again before the velocity ...

third embodiment

[0055] In a third embodiment the invention provides a means of allowing a laundry machine power supply to power down automatically and power up via a low voltage, low current switch. This eliminates the need for a high current and / or voltage rated switch and ensures negligible power consumption when the laundry machine is not in use.

[0056] Referring to FIG. 4 power supply for the machine is produced by employing a simple switch mode power supply (SMPS) topology that is controlled by a microprocessor 17 and makes use of the main motor windings 15 and motor drive circuit 11 to 14. This general form of laundry machine power supply is described in the applicant's Australian Patent 651408. The power supply is disabled by a hardware circuit (fourth wire circuit). Power down functions are initiated by the micro processor and locked by the fourth wire circuit. Power up functions are initiated by the user via a low voltage, low current push button SWI.

Power Down

[0057] When the machine has fi...

fourth embodiment

[0064] In a fourth embodiment the present invention provides a low cost high side drive for an H bridge switching circuit for an electronically commutated motor. Such a switching circuit is shown in FIG. 5 for commutating a three winding motor.

[0065] The present invention provides a more cost effective circuit to that shown in FIG. 6. This is shown in FIG. 7. Here, turn off of Q2 tends to turn on Q1. The value of resistor R is selected to limit the turn on speed of Q1 so there is no risk of overlap. Because this causes a slewed turn on for Q1, this circuit is only appropriate for switching Q1 at low frequency. Therefore the motor must be energised at audible switching frequencies.

[0066] The optocoupler can have relatively low gain and slew rate, which allows the use of a more cost effective device. There is also no need for an inverter such as q4 in FIG. 6.

[0067] Configuring at least one high side drive as in FIG. 7 is necessary to facilitate the power supply ON-OFF concept describe...

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Abstract

An optocoupler drive circuit for the high side of a totem pole power transistor pair in a bridge circuit for commutating a motor includes an optocoupler output device being directly connected to the upper power transistor in the totem pole, and series resistor of selected value for controlling the drive current to said upper power transistor to reduce its speed of turn on.

Description

TECHNICAL FIELD[0001] This invention relates to laundry machines. In particular it relates to laundry machine drain pump control, power supplies, electronically commutated permanent magnet motor drives and motor braking during spin dry cycles.BACKGROUND ART[0002] Most laundry machine drain pumps use an AC induction motor or synchronous motor, operating off the mains frequency, which is typically 50 or 60 Hz. This fixed frequency, along with the mains voltage, determines the design of the pump, and hence the flow rate and maximum head height that can be obtained.[0003] There are numerous disadvantages of a fixed mains-frequency pump motor. These are: (a) the starting torque is typically low, making the pump susceptible to being blocked, (b) separate pump designs are needed for countries having differing mains voltage and frequency, (c) the noise level during "ventilation" is high, particularly when running at a supply frequency of 60 Hz, (d) the torque varies with the mains voltage a...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D06F39/08
CPCD06F39/085Y10T307/826Y02B40/52Y02B40/00D06F2103/48
Inventor CHEYNE, NEILTAYLOR, SAMUEL JOHN SELWYN
Owner FISHER & PAYKEL APPLIANCES LTD
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