US2978892A

US2978892A - Suspension system for an automatic washer

Info

Publication number: US2978892A
Application number: US728321A
Authority: US
Inventors: Curtis E Behrens; Robert D Shapter
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1958-04-14
Filing date: 1958-04-14
Publication date: 1961-04-11
Anticipated expiration: 1978-04-11
Also published as: FR1220533A

Description

April 11, 1961 E. BEHRENS m1 2, 8, 9

SUSPENSION SYSTEM FOR AN AUTOMATIC WASHER Filed April 14, 1958 4 Sheets-Sheet 1 T g .j F

' fnvenz or's April 11, 1961 c. E. BEHRENS ETAL SUSPENSION SYSTEM FOR AN AUTOMATIC WASHER 4 Sheets-Sheet 2 Filed April 14, 1958 April 1961 c. E. BEHRENS ETAL 2,978,892

SUSPENSION SYSTEM FOR AN AUTOMATIC WASHER Filed April 14, 1958 4 Sheets-Sheet 3 j? IIIIII f 721267113715 Curizlfifl fiekrerw and .Foeri D. jig pier A ril 11, 1961 c. E. BEHRENS ETAL 2,978,892

SUSPENSION SYSTEM FOR AN AUTOMATIC WASHER Filed April 14, 1958 4 Sheets-Sheet 4 United SUSPENSION SYSTEM FOR AN AUTOMATIC WASHER Filed Apr. 14, 1958, Ser. No. 728,321

7 Claims. (Cl. 68-24) The present invention relates to clothes washing machines or the like and more particularly to a clothes washing machine of the type having a horizontal basket disposed within a horizontal tub and adapted to be driven at a relatively slow speed for washing the clothes and at a relatively high speed for extracting water from the clothes.

In clothes Washing machines of this type, the tub is subjected to various unbalanced forces and vibrations due primarily to the uneven distribution of clothes in the rotating basket. These movements of the tub occur throughout the Washing and extraction periods but are the greatest at or near the critical speed, that is, that speed between the slow washing speed and the high extraction speed when the vibrations are in resonance with the natural frequency of the tub. While the vibrations and oscillations are in all directions, the horizontal vibrations are those which cause the clothes washing machine to creep about the floor on its feet.

It is therefore an object of the present invention to isolate the horizontal forces and prevent the machine from creeping. This object is accomplished by pivotally suspending the tub of the washing machine on a base struc ture in the manner of an inverted pendulum to allow movement of the tub in a horizontal are but preventing movement of the tub vertically with respect to the base structure. Tension springs are connected to the tub and rates Fatent the water are added. The higher the critical speed, the greater are the problems encountered. Vibration isolation itself improves as the ratio of the spin speed to the critical speed increases or to state it differently, with a given spin speed, the lower the critical speed or natural frequency speed, the better the isolation. A critical speed of approximately 110' revolutions per minute is sufficiently high enough to cause centrifugal forces due primarily to unbalanced clothes loads that will result in uncontrolled movements of large amplitude of the tub. It is for this reason that the present washing machine has its natural frequency adjusted to about 50 cycles per minute.

It has been the practice in the past to suspend the tub on superstructure within the cabinet for the machine. It is another object of the present invention to eliminate such methods of suspension and to support the tub solely on a base support structure. -By the use of such a mounting system, no bulky framework is required nor is thcre any stress on the cabinet. Also, the metal requirements for t the cabinet covering the tub are materially reduced. The

the base structure at either side of the pivotal mounting to give lateral stiffness to resist the deflections of the tub during slow speed washing and to resist the torque reactions of the tub horizontally when the speed of the basket is accelerated from slow speed wash to high speel extraction. A friction pad is placed between the tub and its base to provide friction damping for the tub.

The springs are also utilized to adjust the natural frequency of the system. It has been found that by adjusting the springs to give a natural frequency of 50 cycles per minute to the system that no uncontrolled vibrations occur in going from slow wash speed to high extraction speed. It has also been found that low natural frequencies on the order of 10-30 cycles per minute improve vibration isolation but when the springs are so ad justed, and with the friction pad engaged, there is insufiicient centering effect by the springs on the tub. To adjust the natural frequency at some value above the low wash speed (50 cycles or revolutions per minute) causes complications which have plagued the horizontal type Fig. 2 and showing the front pivot for the tub of the Washing machine;

Fig. 4 is a cross-sectional view showing the rear pivot for the tub; I

Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 2 and showing a vibration dampener used in the present machine; v

Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 7 is a cross-sectional view of a modified form of front pivot for the tub;

Fig. 8 is-a cross-sectional view of a modified form of rearpivot;

Fig. 9 is a plan view mechanism; and

Fig. 10 is a cross-sectional view taken on line 10-19 of Fig 9.

Referring to the-drawings, there is disclosed a horizontal washing machine comprising in general an imperforate tub A, a perforate clothes receiving cylinder or basket B adapted to be rotatably disposed within the tub A, a supporting base structure C, pivots D and E for attaching the tubA to the base" structure, an electric motor F attached to and suspended from one side of said tub, a two-speed transmission G attached to and suspended from the other side of said tub, a pairrof weights H and I for adding weight to the assembly to provide inertiadamping, and a housing or casing J for enclosing vibration-isolated washing machine since 'its inception.

In prior machines, the rotating cylinder must pass through the critical speed or naturalfrequency speed when accelerating from thelow wash speed to the high extraction speed. Thus, horizontal axis washers that permit vertical movement of the tub must, for practical reaseveral inches in the cabinet when the clothes load and the aforementioned structure.

The pivots D and E are provided directly below the; center of the tub A. A; pair of front and rear brackets 10 and 11 are suitably secured to the bottom of the tub A. Plates l2 and Bare fastened respectivelyby Each

ofithe plates

12 and 13 has an opening 20 therein and a bushingzl is mounted in thisopening. Inorder of a modified form dampener I to provide for movement of the tub A relative to the base structure C, a bearing sleeve 22

surrounds bolts

17 and 18 and in order to provide a resilient pivot, a rubber sleeve 23 isdisposed between the bearing sleeve 22' and the bushing 21. 1' Y 1 i t A pair of springs 24wand 25 are provided on opposite sides of the pivot D and the ends of the springs are attached to the'tub'A and the base structure C. The springs are required to give suflicient lateral stifiness to resist the deflections of the tub caused bythe tumbling clothes load (slow speed) and the torque reactions ficient lateral stifiness and resistance to resist the deflections of the tub.

caused by the acceleration'of the cylinder from the'lo w speed wash cycle to the high speed spin cycle, and also utilized for determining the natural frequency of the system. As before pointed out, the pivots D and E permit relative movement of the tub A with respect to the of the tubassembly, improving isolation by reducing'the amplitude of vibration.

In addition to the use of the springs24 and 25 to resist the deflections of the tub A caused by the tumbling clothes loadduring the low speed wash cycle, there is provided a vibration dampener indicated generally by the reference numeral 27. The vibration dampener 27 comprises an arm 28 fixedlysecured to and depending from the tub A and engaging a pair of

friction pads

29 and 30 fixed by means of

plates

31 and 32 to the supporting base structure C. The plate 31 is fixed to the channel member by means of a plurality of bolts 33 and the plate 32 is spring pressed against the friction pads and the plate 31 by means of bolts 34 and 35 having associated therewith

springs

36 and 37. 7 Nuts 38 and 40 engage the

springs

36 and 37 and aretightenedon the bolts 34 and '35 to adjust the engagement 7 of the pads 29 and '30 against the arm 28. V I i i The clothes receiving cylinder or basket B is adapted to be rotated at a slow speed (approximately 50 rpm.) for tumbling the clothes during the' washcycle of the machine and at a high speed (approximately 200 r.p.m. v

The electric motor F and the two speed transmission G have; suitable as above) duringthe-water extraction cycle.

connections with" the basket B 'for providing these two basket speeds. The basketB is'rotatably supportedon the tub A at the front thereof by means of a plurality of rollers 41 and at the rear thereof by means of arotatable shaft 42; A pulley 43 is fixedly secured tothe shaft 42 and a belt 44 is connected betwee n the pulley,43 and a transmission output pulley 45. 5 A transmission input pulley 46 is connected to an electric motor output pulley 47 by means of a driving belt 48.

' b In operation, a load of clothes is placed in the basket B and suflicient'water is placed in the tub A as is the usualpractice; suitable switch means (not shown) are actuated to energize the electric motor F andthe basket is rotatedrat slow speed: to tumble the clothes; The tub A will tend to deflect horizontally but will be restrained springs 24 and 25 will restore the jtub to' its upright provides acentering force for the tub and are further 7 A modified form of base structure and pivot means are shown in Figs. 7 and 8. L-shaped frame members 50 and 51 have attached thereto and spaced therefrom at the area of the pivots D and

E channel members

52 and 53. The channel .membersVSZ andj53 and the frame members 50' and 51' are provided with aligned openings for receiving

bolts

54 and 55.

Bushings

56 and 57 are provided in plates 58 and '60 and a rubber sleeve, 61 is mounted between

bearing sleeves

62 and 63. A portion is struck out of the charinel members '52 and 53 adjacent the bolt receiving openings to'provide abolt lock 64.

Atmodified form of vibration dampener is shown in Figs. 9 and 10. This dampener comprises, in general, a stationary plate, or arm 65 attached to a frame member 66 by means of bolts 67 and a pair of

friction pads

68 and 70 straddling the plate 65 and fixedly secured to the tub A by means of a'bifurcated support 71. The

pads

68 and 70 are urged against the arm 65 through plates '72, 73 and a spring loaded bolt 74.

While We have described our invention with specific embodiments thereof, it is to be understood that this is by Way of illustration and not by way of limitation and the scope of our invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit. a

We claim: J a

1. In a clothes washing machine, adapted to have a 7 Washing period and an extraction period, a tub, a basket journalled in said tub for rotation about a horizontal axis, a base structure, means for rotating said basket at a low speed during the washing period and at a high speed during the extraction period, means for solely supporting said tub and basket on said base structure, said means comprising pivot means on the bottom of said tub beneath the center of said tub for attaching said tub to the base structure, and means on opposite sides of said pivot and attached to said tub and said base structure to resist deflections of said tub in a horizontal direction,

- 2 .'-In a clothes washing machine; adapted to have a said pivot and attached to said tub and said base structure to resist deflections of said-tub in a horizontal direction. a r

3; In a clothes washing machine, adapted to have a washing period and an extraction period, a tub, a basket journalled in said tub for rotation about a horizontal axis, a base structure'meansfor rotating said basket at a low speed during the washing period and at 'a high speed I during the extraction period, means for solely supporting said tub and basket on said base structure, said means 7 comprising pivot means on the bottom of said tub beposition. Afterithe:clothes have been washed by: slow 'speedtumblingQthe transmission is shifted to its high-t speed position by 'suitable'mean's (not shown) toextract the water fr'omfthe clothes. When the transmission is shifted from low speed 'to' high speedand as the basket accelerates injjspeed, the tub will tend to deflect horia zo'ntally but again as inQtumbling speed the springsj24 and 25-aud the vibrat'ion dampener 27 will provide sufneath the center ofsaidrtub for attaching said tub to the basestructure, and means on opposite: sides of said pivot andattached to said tub and said baseistructure to resist deflections of saidtub in ahorizqntal direction, said last named'm'eans including springs attached to the bottom ,of said tub at opposite sides of said pivot to said base axis,a base structure, means for rotating said basket at a low speed during the washing period ,andnta high speed during the extraction period, means for solely supporting said tub and basket on said base structure, said means comprising pivot means on the bottom of said tub beneath the center of said tub for attaching said tub to the base structure, and means for controlling the amplitude of vibration of said tub at substantially said low speed.

5. In a clothes washing machine, adapted to have a washing period and an extraction period, a tub, a basket journalled in said tub for rotation about a horizontal axis, a base structure, means for rotating said basket at about 50 cycles per minute for the washing period and at above about 175 cycles per minutes for the extraction period means for solely supporting said tub and basket on said base structure, said means comprising pivot means on the bottom of said tub beneath the center of said tub for attaching said tub to the base structure, and means for adjusting the amplitude of vibration of said tub to about 50 cycles per minute.

6. In a clothes washing machine, adapted to have a washing period and an extraction period, a tub, a basket journal led in said tub for rotation about a horizontal axis, a base structure, means for rotating said basket at a low speed during the washing period and at -a high speed during the extraction period, means for solely supporting said tub and basket on said base structure, said means comprising pivot means on the bottom of said tub beneath the center of said tub for attaching said tub to the base structure, and means for adjusting the amplitude of vibration of said tub.

7. In a clothes washing machine, adapted to have a. washing period and an extraction period, a tub, a basket journall'ed in said tub for rotation about a horizontal axis, a base structure, means forrotating said basket at a low speed during the washing period and at a high speed during the extraction period, means for solely supporting said tub and basket on said base structure, said means comprising pivot means on the bottom of said tub beneath the center of said tub for attaching said tub to the base structure, and means for adjusting the amplitude of vibration of said tub, said last named means including weights on the top of said tub at substantially the most distant point from said pivot means.

References Cited in the file of this patent UNITED STATES PATENTS 2,311,545 Hurley et a1 Feb. 16, 1943 2,526,048 Russell Oct. 17, 1950 2,692,681 Douglas Oct. 26, 1954 2,813,415 Clark Nov. 19. 1957