Speed Equalizing Means and/or Laundry Machines Incorporating the Same

This invention relates to speed equalizing means and/or a laundry machine incorporating the same and has been devised particularly though not solely for use in absorbing energy as between a first rotatable member and a second rotatable member substantially stationary in one mode of operation, for example, between the agitator and spin tub drives in an agitating type laundry machine.

It is an object of the present invention to provide a speed equalizing means and/or a method of operating the same, and/or a laundry machine incorporating the same.

Accordingly in one aspect the invention consists in a method of equalizing the speeds of rotation of two coaxial rotatable members one of which includes a spin tub and the other of which includes an agitator and associated shaft of a laundry machine, comprising the steps of interconnecting the rotatable members through interconnecting contacting members spaced radially from the axis of said rotatable members and transmitting the force from at least one of said contacting members to its respective rotatable member through an energy absorbing device so as to absorb energy resulting from the change in relative speeds necessary to achieve speed equalization of said rotatable members.

In a further aspect the invention consists in speed equalizing means for use in equalizing the speeds between two coaxial rotatable members one of which includes a spin tub and the other of which includes an agitator of a laundry machine, said speed equalizing means comprising interconnecting contacting members spaced radially from the axis of said rotatable members, at least one of said contacting members being connected to its respective rotatable member through an energy absorbing device which in use absorbs energy resulting from the change in relative speeds necessary to effect speed equalization of said rotatable members.

In a further aspect the invention consists in a laundry machine which includes an agitator as a first rotatable member and a spin tub as a second rotatable member, and speed equalizing means between said rotatable members according to the preceding paragraph mounted so that relative movement between said agitator and said spin tub greater than a permitted movement results in interconnection of said contacting members.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

One preferred form of the invention will now be described with reference to the accompanying drawings wherein:

FIG. 1 is a diagrammatic cross-sectional view of part of a laundry machine showig such parts as are necessary to illustrate the present invention;

FIG. 2 is a cross-sectional view of a gripping member forming part of a gripping means according to the invention; and

FIG. 3 is a plan top view of part of a sliding member according to the invention.

Referring to the drawings a laundry machine is provided such as that described in our copending New Zealand patent applications Nos. 196638/198577. In such a machine a driving pulley 1 rotates an agitator shaft 2 connected to the agitator of the laundry machine and coaxial with the agitator shaft 2 is a spin tub hollow shaft 3. These two shafts are carried in bearings and rotate or are stationary in accordance with the required washing sequence. An electronically commutated electric motor and associated circuits are provided to oscillate the agitator backwards and forwards over a permitted range of movement (usually less than 2.pi. radians) in an agitating mode and to drive the agitator and spin basket continuously in one direction in a spin mode. These modes are well known.

The motor and control are preferably such as is described in European Patent Application Publication No. 38694 General Electric Company or less preferably specification U.S. Pat. No. 3,783,359 Bendix.

An energy absorbing device is provided between the rotatable members comprising the shafts 2 and 3 as follows. Associated with the pulley 1 is a gripping means forming parts of the energy absorbing device and gripping a pair of gripping members 4 and 5, one of which is shown in more detail in FIG. 2. Each gripping member includes an annular groove 6 and the two members are bolted together e.g. by assembly bolts 7. Engaged between the grooves 6 in members 4 and 5 in the assembled condition shown in FIG. 1 is a sliding member 10 forming a further part of the energy absorbing device and shown in more detail in FIG. 3. The sliding member 10 has a bulbous member 11 which conforms to and is engaged by the inner surfaces of the grooves 6 and preferably the grooved members 4 and 5 are made of a stiffly resilient material, for example stainless steel, and the sliding member 10 is made of a compressible frictional material, for example, acetal or polyamide material such as a nylon either with or without friction additives. The sliding member 10 is provided with an extension 12 and to provide releasable interengagement between the agitator shaft 2 and the spin tub shaft 3 a driving arm 13 forming one interconnecting contacting member which is fixed to the shaft 3 is engageable with either side of the extension 12, which forms the other interconnecting contacting member being otherwise freely rotatable over very close to a full turn of 2.pi. radians. Thus the agitator may be agitated almost up to a full turn when in the agitation mode without the arm 13 contacting the extension 12.

In use when the pulley 1 is in the agitating mode of the laundry machine, and is rotated backwards and forwards through a permitted angle, usually only slightly less than 2.pi. radians, the gripping members 4 and 5, the sliding member 10 and the arm 12 also rotate backwards and forwards through something less than 2.pi. radians. In the event however that there is some movement of the stationary (in the agitating mode) shaft 3 and consequently arm 13, the arm 12 may in some circumstances engage the arm 13 and to absorb energy as between the rotating member 1 and the stationary but rotatable member 3 the sliding member 10 slides in the grooves 6 of the members 4 and 5. More importantly however, when changing from agitate to spin mode or more, particularly from spin to brake mode, the driving arm 13 must pick up the spin tub shaft 3 at a time when there may be a considerable relative speed difference between the two, so that the energy in the rotating member needs to be absorbed by the frictional engagement between the sliding member 10 and the gripping members 4 and 5. Thus both in the case of inadvertent engagement and deliberate engagement, (but more importantly the latter) because of the stiff resilience of the grooved members 4 and 5 and/or the compressibility of the sliding member 10 there is frictional sliding contact between grooves 6 and the sliding member and this frictional contact absorbs energy due to the engagement of the member 11 with the arm 12. As a result there tends to be a smooth engagement between the two members and the shock of engagement of the members when they contact each other is reduced.

Clearly the frictional resistance offered by the energy absorbing device must be sufficient to enable the transmission of enough energy to accelerate the spin tub to spin speed, to maintain that spin speed without slipping of the sliding member 10 relative to the gripping members 4 and 5 and to resist the forces occurring when braking the spin tub after spinning has occurred. Because braking deceleration must be effected in a much shorter time than acceleration, it will be apparent that the braking forces impose the greatest requirements on the frictional resistance.

The gripping members 4 and 5 and the bulbous member 11 may be reversed i.e. the grooves gripping members 4 and 5 may have ribs instead of grooves and grooves may be provided in the sliding member 10. One or the other of the set of grooves and the bulbous member may be discontinuous e.g. not a full annulus if desired. Although a coacting bulbous member and grooves are described above, other coacting arrangements may be used, e.g. a series of ridges and valleys in both members or one member may be of flat e.g. disc form or one of cylindrical form, the other member coacting with such disc or cylindrical form.

If desired a further energy absorbing device could be inserted between driving arm 13 and the shaft 3, constructed in a similar way to that described above.

It will be seen that by this construction a very simple arrangement results which enables a smoothing of the engagement of the members 12 and 13 one with the other during operation of the laundry machine.