Laundry machine with lost motion clutch

The present invention relates to laundry machines and in particular to laundry washing machines having a spin basket and an independently rotating agitator within the spin basket.

In 1991 Fisher & Paykel Limited released the first model of their SMARTDRIVE washing machines. This machine included a cabinet, a tub suspended within the cabinet by a plurality of suspension rods extending between the top edge of the cabinet and a lower portion on the tub. A single shaft extended through the base of the tub. The stator of a salient pole electronically commutated brushless DC motor was fixed to the lower side of the tub base. An external permanent magnetic rotor was fitted to the lower end of the shaft to substantially surround the stator. Within the tub a spin basket was supported for rotation on the shaft. Within the spin basket an agitator was fixed to the upper end of the shaft. The agitator was of a central post type with three lateral vanes and a generally conical base portion. The spin basket was supported by the shaft at a lower position, was free to rise on the shaft to an upper position. The spin basket included downwardly facing hollow chambers. Vertical support of the spin basket on the shaft in the lower position included inter-engagement of a downwardly facing castellated clutch on the spin basket and an upwardly facing castellated clutch fixed to the shaft. Accordingly without sufficient wash liquid in the tub for the spin basket and any associated load to float the spin basket remained rotationally fixed to the shaft. With sufficient wash liquid in the tub the float chambers of the spin basket would provide for the basket and load to float and disengage from the shaft such that the spin basket and shaft would rotate. This arrangement is described in U.S. Pat. No. 5,353,613. This direct drive electronically controlled laundry machine has been very successful. A number of competing companies have sought to devise alternative arrangements for selectively transmitting power of the motor to the spin basket.

U.S. Pat. No. 6,212,722 proposes an improved laundry washing machine for domestic use. This machine is of the top loading type having an outer bowl, a wash basket within the outer bowl and access to the wash basket through a top opening. A motor is provided to drive rotation of the wash basket within the outer bowl. A wash plate is provided in the lower portion of the wash basket to be rotated by the motor with the wash basket or independently of the wash basket. The patent proposes a combination of water level control, wash plate design, wash basket design and movement pattern for the wash plate which leads to an inverse toroidal movement of the laundry load during a wash phase. The sodden wash load is dragged radially inward on the upper surface of the wash plate and progresses upward in the region of the centre. The sodden wash load then progresses radially outward to the wall of the wash basket and downward to the base of the wash basket. This has been found to provide an effective wash action with low water consumption.

When a wash system of the type disclosed in U.S. Pat. No. 6,212,722 is applied to a machine of the type described in U.S. Pat. No. 5,353,613, the water volume required to operate the floating clutch can be a significant factor in overall water consumption.

U.S. Pat. No. 4,803,855,Kennedy, describes an agitate and spin drive for a washing machine. The mechanism includes a pair of concentric shafts extending through the lower wall of the wash tub. The upper end of the inner shaft is connected to drive the agitator. The upper end of the outer shaft is connected to drive the wash basket. A pulley at the lowest end of the inner shaft is driven by an electric motor. A lost motion mechanism or clutch in the form of a plurality of stacked disks is mounted on the agitator shaft. A lower end of the lost motion clutch is driven by the pulley. An upper end of the lost motion mechanism drives the lower end of the wash basket shaft. The lost motion clutch mechanism is located in the area between the base of the wash tub and the drive pulley. The overall arrangement requires both the wash basket shaft and agitator shaft to penetrate the wash tub.

U.S. Pat. No. 2,273,566 illustrates a washing machine with an agitator housed within a wash basket. The wash basket includes a central hub 41 extending up inside the post of the agitator. A lost motion clutch acts between the inner surface of the agitator and the outer surface of the hub. The clutch allows less than one revolution of relative movement between the wash basket before the agitator begins to drive the wash basket.

U.S. Pat. No. 2,609,697 describes a washing machine with an agitator housed within a wash basket. The wash basket is rotatably supported on the drive shaft. The agitator is fixed to the drive shaft. A downward extending lug on the agitator skirt is positioned to engage against an upward lug on the floor of the wash basket. The clutch allows less than one revolution of relative movement between the wash basket before the agitator begins to drive the wash basket.

It is an object of the present invention to provide a laundry machine which goes some way toward overcoming the above disadvantages or which will at least provide the public with a useful choice.

In a first aspect the invention consists in a laundry machine comprising:

• • a tub,
  • a spin basket in said tub,
  • a drive assembly comprising a shaft and agitator, the shaft passing through a wall of the spin basket, said agitator being located within said spin basket,
  • a lost motion clutch physically located in the tub, interconnecting between the drive assembly and the spin basket and absorbing greater than one revolution of relative rotation.