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Publication numberUS3114705 A
Publication typeGrant
Publication dateDec 17, 1963
Filing dateAug 20, 1962
Priority dateAug 20, 1962
Publication numberUS 3114705 A, US 3114705A, US-A-3114705, US3114705 A, US3114705A
InventorsPrihonic John F, Whelan James E
Original AssigneeGen Motors Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Means for controlling the dampening of an elastically suspended rotating drum duringcentrifuging
US 3114705 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

1963 J. F. PRlBONlC ETAL 3,114,705

MEANS FOR CONTROLLING THE] DAMPENING OF AN ELASTICALLY SUSPENDED ROTATING DRUM DURING CENTRIFUGING Filed Aug. 20, 1962 v 2 Sheets-Sheet 1 John E Pribqnic BY James E.Whe'lan Their Attorney 1963 J. F. PRIBONIC ETAL 3, ,705

MEANS FOR CONTROLLING THE DAMPENING OF AN ELASTICALLY SUSPENDED ROTATING DRUM DURING CENTRIFUGING Filed Aug. 20, 1962 2 Sheets-Sheet 2 INVENTORS United States Patent 3,114,705 MEANS FUR COIITRULLING THE DAMPENING OF AN ELASTICALLY SUSPENDED RGTATlNG DRUM DURING CENTRIFUGING John F. Pribonie and James E. Whelan, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich a corporation of Delaware Filed Aug. 29, 1962, Ser. No. 218,012 9 Claims. (Cl. 210-145) This invention relates to a domestic appliance and more particularly to a hydraulic shock absorber for a horizontal tumbling drum or other elastically suspended rotating system.

Washing machines utilizing centrifugal extraction present a problem in balance. Some of these machines use a rotatable, perforated, clothes containing cylinder or drum mounted for rotation on a substantially horizontal axis, the clothes being inserted in the drum and rotated at relatively slow speed in the presence of a washing liquid for washing the clothes. This wash liquid is subsequently drained from the clothes cylinder and the liquid is extracted from the clothes by increasing the speed of rotation of the drum until the centrifugal force generated by the increased speed causes the water contained in the clothes to be thrown through the perforations of the drum. Occasionally, unbalance occurs due to imperfect distribution of the clothes around the periphery of the drum. Such unbalance requires that either the machine be secured to the floor or otherwise provided with resilient support properly damped to assure that excessive machine vibrations will not be transmitted to the floor.

In rotating unbalanced masses, the largest excursions of the rotating mass occur at What is referred to as the resonant frequency of the suspended mass. With a clothes spin drum, for instance, the resonant frequency is some where between 100 and 200 r.p.m. Once the suspended mass passes through its resonant frequency, the excursions are less and there is no need for damping action. Actually, all damping which occurs in the rotating or vibrating system above its resonant frequency is reflected as additional work required of the drive motor. In other words, energy absorbed by the damping or snubbing action of shock absorbers, for instance, must be supplied by the motor itself. Thus, even though the vibrations above resonant are not sufficient to require damping in a washing machine, unnecessary work is being expended with the prior art devices in controlling these vibrations. The motors required to rotate spin drums in domestic Washers today are sized at their upper limit, according to U.L. standards, without going into permanently wired installations. If the spin speeds of drums are to be increased, a means must be found to reduce motor power requirements elsewhere in the rotating system. This invention, then, is directed to a hydraulic shock absorber for a rotating drum which is effective to dampen vibrations only in the range of the rotating drums resonant frequency and which includes means for effectively eliminating damping action above the resonant frequency of said drum, thereby to reduce the power requirement on the motor when the drum is at its maximum spin speed.

Accordingly, this invention is directed to apparatus for reducing power required to rotate damped, elastically suspended, vibrating masses above system resonant frequency and of reducing the transmissibility of the disturbing force.

Another object of this invention is the provision of a shock absorber for damping the excursions of an elastically suspended, vibrating mass, said shock absorber including a frequency sensitive valve to eliminate the damping action of the shock absorber only above the resonant frequency for the vibrating mass.

A more specific object is the combination of an elastically suspended, non-vertical axis, rotating clothes drum with a hydraulic shock absorber having a frequency sensitive valve openable during drum acceleration at some preselected frequency above the resonant frequency of the rotating drum to allow the hydraulic fluid to bypass the normal control valves of the shock absorber and closable during drum deceleration as said resonant frequency is approached to permit the control valves of the shock absorber to become effective.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a generally schematic rear view of a horizontal axis, rotating drum machine with the back removed to show the general arrangement of parts;

FIGURE 2 is a generally schematic side sectional view taken along line 2-2 in FIGURE 1;

FIGURE 3 is a fragmentary side sectional view of the shock absorber of this invention in an at rest position;

FIGURE 4 is a fragmentary side sectional view with the frequency sensitive valve means in one by-pass position during the compression stroke of the shock absorber; and

FIGURE 5 is a view similar to FIGURE 4 with the frequency sensitive valve means in another by-pass position during the rebound stroke of the shock absorber.

In accordance with this invention and with reference to FIGURES 1 and 2, a horizontal drum-type combination washer-dryer 6 is shown comprised of a box-like casing enclosing a generally imperforate cylindrical water container 7 suspended along a top portion thereof by four springs 8 and damped along its bottom by a pair of hydraulic shock absorbers 9. A perforate tumbling drum or centrifuging means 10 rotatable about a generally horizontal axis is rotated by an electric motor .11 through a belt and pulley system 5. Fabrics, such as clothing placed into the tumbling drum 10 through a front access opening in the casing, are washed when water, admitted by any suitable conventional means, is agitated with the fabrics as the tumbling drum 10 is rotated by the motor 11.

An elastically suspended vibrating mass or system 17, such as the water container 7, tumbling drum 10 and motor 11, usually requires damping to enable the vibrating system to pass through the resonant frequency thereof without causing damage to the component parts of the appliance due to excessive movement of the system. Such damping or snubbing is accomplished by installing one or more of the shock absorbers 9 in parallel with the suspension springs 8.

Since snubbing action produces no desirable effect at frequencies above the resonant frequency, it would be beneficial to remove part or all of the damping force after the operating frequency of the system exceeds its resonant frequency. This would lower the power requirements of the vibrating system and would permit the use of less powerful motors 11.

Referring now to FIGURE 3, the shock absorbing element 9 of this invention is comprised of a cylinder 12 closed at the bottom end thereof by a base valve and cap 14 and at the top by a cap 16. An actuating rod 13 is journaled in the cap 16, the cap forming a guide for the rod 13. The upper end 15 of the rod is connected to the elastically suspended, vibrating mass 17 comprised of the water container 7, drum 10 and motor 11.

An outer cylinder 18 is positioned around the cylinder 12 and has the lower end thereof closed by a cap 20. The cap 20 carries any suitable fitting 21 connectable with the unsprung mass, such as the frame of the combination washer-dryer 6. The upper end of the outer cylinder 18 has welded thereto a closure member 22, whereby to provide a reservoir space 25 for hydraulic fluid. The reservoir space 25 connects with the interior of the cylinder 12 through the base valve 14, passages 26 being provided for flow of fluid between the reservoir and the interior of the cylinder 12 by the spacing of the caps 14 and 20.

The base valve 14 consists of a valve member 31 which provides for an upward flow of fluid from the reservoir into the interior of the cylinder 12. More particularly, the valve 14 consists of a valve element 31 positioned within a valve bore 32 in the closure wall 27, the valve element 31 having a radially extending annular flange portion 33 that engages the valve seat 34 to close the valve bore 32. A light finger spring 35 holds the valve ele ment 31 on the seat 34 but provides little resistance against lifting of the valve from the seat for flow of hydraulic fluid from the reservoir chamber 25 into the fluid receiving chamber of the cylinder tube 12.

The valve element 31 has an axial bore 36 that receives a valve element 37 seated against the valve seat 38 by the compression spring 39, an axial opening 40 providing for flow of hydraulic fluid from the lower portion of the cylinder tube 12 against the upper side of the valve 37 through a radial slot 29. The compression spring 39 controls the point of opening of the valve 37.

The upper end of the shock absorber carries a resilient seal member 41 that is retained between the cap member 22 and a seal ring 43 that is spring-urged against the seal 41 by means of a compression spring 42. The seal 41 prevents leakage of hydraulic fluid from around the rod 13. Any hydraulic fluid passing upwardly along the rod 13 through the guide member 16 is returned to the reservoir chamber 25 through passage 44.

A piston 50 reciprocatingly slidable in the cylinder 12 is carried on the lower end of the actuating rod 13, the piston having suitable valve passages to control flow of hydraulic fluid through the piston and between the compression chamber 51 and the rebound chamber 52 defined within the cylinder 12 by the position of the piston therein.

The piston 50 has a valve assembly 55 on one end there-- of effective during the compression stroke of the shock absorber and a valve assembly 60 that is effective during the rebound stroke. The valve assembly 55 comprises a valve disk 61 that is positioned upon a pair of annularly arranged annular valve seats 62 and 63 on one end of the piston 50. An annular recess 64 is provided between the valve seat 62 and 63, which recess communicates with outboard passages 65 extending therefrom to the opposite end of the piston. The series of fluid flow passages 65 provide for flow of hydraulic fluid from the compression chamber 51 to the rebound chamber 52 under control of the valve 61. The piston 50 has a second inboard series of fluid flow passages 68 providing for flow of hydraulic fluid from the rebound chamber 52 to the compression chamber 51 through ports in the valve disk 61 and under control of the valve 60. A compression spring 70 controls the opening point of valve 60 while a disk spring 72 controls the opening point of valve 61.

The shock absorber thus far described will function in a substantially normal manner wherein movement of the piston 50 toward the base valve 14 will place fluid under compression in the chamber 51 on the compression stroke, excess fluid that is not displaced into the rebound chamber 52 through the valve 61 being discharged under pressure through the base valve 14 under control the valve element 37. The volume of fluid flow through the base valve 14 is equivalent to the displacement of rod 13 that enters the rebound chamber 52. On the return stroke or rebound stroke, fluid will flow from the rebound chamber 52 into the compression chamber 51 under control of the valve 60. Make-up fluid to fill the chamber 51 on movement of the piston 50 away from the base valve 14 will be received from the reservoir 25 through the bore 32 of the closure wall 27, valve element 31 opening against the disk spring 35 for this purpose.

Prior art combinations of shock absorbers with rotating drums utilize shock absorbers which are active to dampen vibrations of the rotating drum or vibrating mass throughout an entire range of rotational speeds, whether or not damping is desirable or needed. In other words, the prior art shock absorber combinations were effective to dampen the dangerous large excursions of the vibrating system 17 as the mass passed through its resonant frequency as well as the harmless small vibrations occurring after the mass arrived at its normal operational spin speed or frequency. Since any damping action expends energy and the only input to the system is through the motor 11, such prior art arrangements require overly large motors 11.

The method of this invention in reducing the power required to drive a damped, elastically suspended, vibrating mass above the resonant frequency of the vibrating system also reduces the transmissibility of the disturbing force because the reduction of damping force reduces the damping factor of the hydraulic shock absorbers 9.

The novel combination of this invention incorporates a frequency sensitive by-pass valve or inertia valve assembly, shown generally at 80, which is designed so that its own natural resonant frequency is the same as the operational frequency of the vibrating mass. Assuming the combination washer-dryer 6, for instance, has a maximum drum spin speed of 650 r.p.m. during centrifuging, the frequency sensitive by-pass valve assembly will be designed with a natural frequency of 650 cycles per minute. In this Wa the by-pass valve assembly 80 is effective to render the shock absorber ineffective at drum speeds above the resonant frequency of the vibrating system 17, which, in the case of the combination washerdryer 6, is approximately 160 c.p.m. Thus, the shock absorber is effective to dampen large excusions of the vibrating system as the drum 10 is accelerated through the resonant speed of 160 rpm. However, when system vibrations are small as the drum 10 reaches its maximum extraction speed of 650 r.p.m., the damping action of the shock absorbers is effectively eliminated altogether and the drag on the motor 11 is reduced proportionately.

More particularly, the frequency sensitive by-pass valve assembly 80 is comprised of an inertia valve member 82 of inch C.D. steel weighing 0.1 pound and reciprocatingly movable on a /8 inch OD. x 0.028 wall steel tubing valve guide 84 at one end of which is a inch diameter C.D. steel spring seat 86. The valve member 82 is urged by a first compression spring 88 in one direction and by a second compression spring 90 in the opposite direction. Since the valve guide 84 has a pair of bypass ports 92 at one end thereof and a pair of by-pass ports 94 at the other end thereof, the valve member 82 will be effective to open the ports 92 when inertially shifted to its lowermost position (FIGURE 5) against the restraining bias of spring 90 and effective to open the ports 94 when inertially shifted to its uppermost position (FIGURE 4) against the restraining bias of the spring 88. It should be understood that by-pass port means could be established at one point only on the guide 84 by having the valve member 82 shift completely past the opening in each direction.

With the vibrating system 17 having a drum extraction speed of 650 rpm. and a resonant frequency of rpm, the frequency sensitive by-pass valve assembly 30 can be designed with the same natural frequency (650 cycles per minute) if the spring 88 is made of music wire 0.040 inch in diameter having eight total turns, six of which are active turns, and a free length of l.200 inches. On the other hand, the opposing spring 90 may be made of music wire 0.028 inch in diameter having seven total turns, five of which are active turns, and a free length of 0.950 inch.

Anyone skilled in the art will know that calculations including the dimensions of springs 88 and 90 and valve member 82 will give a natural frequency of 900 cycles per minute. This is true in air, but when the assembly is built into a shock absorber as shown in FIGURE 3 and the piston rod 13 cycles on a test machine, the test results will indicate a natural frequency of approximately 650 cycles per minute. This peculiarity can best be explained by saying that the effective mass of valve member 82 is not 0.1 pound but 0.1 pound plus the force produced by shock absorber fluid striking the end of the valve member at some appreciable velocity.

Cooperating with the bypass ports 92 or 94 is a passageway 96 through the actuating rod 13 which selectively interconnects the rebound chamber 52 with the compression chamber 51 through the interior of the valve guide 84.

In operation, the valve member 82 will remain in its closed position shown in FIGURE 3, moving in phase with the piston 50 and the ports 92, 94 as the vibrating system 17 moves through its resonant frequency (drum speed increasing from rpm. to 160 r.p.m.). During this time, the shock absorber 9 will be effective to dampen the unbalance created excursions of the vibrating system where needed. However, as the drum 10 accelerates above its resonant speed of 160 r.p.m. to its maximum spin speed of 650 r.p.m., the by-pass valve member 82 will start to partially uncover alternately ports 2 and 94 and will gradually increase its port uncovering travel until the valve member is vibrating at its own natural frequency of 650 cycles per minute but trailing 90 out of phase with the piston St) at which point the drum 10 will be rotating at its top speed and the ports 92 and 94 will be alternately fully open. In other words, the valve 82, at its natural frequency, will be in its closed position (FIG- URE 3) whenever the piston 50 is at either extreme position in the cylinder 12. When the piston is at the midpoint of its travel in either direction, however, the valve member 8'2. will be in one or the other of its extreme positions (FIGURES 4 and 5), uncovering either the ports 94 or 92 respectively to interconnect the compression chamber 51 with the rebound chamber 52, thereby effectively eliminating the damping effect of the shock absorber 9.

As the drum decelerates at the conclusion of spin through its resonant frequency at 160 rpm, the valve member 82 will again become effective to gradually close the ports 92 and 94 so that the shock absorber will be completely effective to dampen the large excursions of the unbalanced rotating mass at system resonant.

It should now be seen that an improved method has been provided for reducing power required to drive a damped, elastically suspended, vibrating mass above the resonant frequency of the system. The combination of a shock absorber having a frequency sensitive bypass with a rotating mass also reduces the transmissibility of the disturbing force because the reduction of damping force reduces the damping factor of the hydraulic shock absorber. Power requirements are thus reduced in rotating systems, such as washing appliance spin drums, so that higher spin speeds are possible without increasing the size of the prime mover therefor.

While the embodiment of the present invention, as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a clothes washing machine, the combination of means forming a casing, means in said casing defining a water container, a clothes tumbling drum rotatably dis posed in said Water container means, means for rotating said tumbling drum about a non-vertical axis for extracting water from clothes contained therein, said water container means, tumbling drum and rotating means defining a unitary system, means for elastically supporting said unitary system in said casing means for movement in vertical and horizontal directions, sa-id rotating means effecting rotation of said tumbling drum from standstill to an extracting speed above the resonant frequency of the elastically supported unitary system, and damping means comprising a hydraulic shock absorber secured between said casing means and said water container means, said hydraulic shock absorber having a cylinder with a reciprocable piston disposed therein dividing the cylinder into opposed chambers, the piston having passage means therethrough for effecting a first flow path of hydraulic fluid between said opposed chambers while said rotating means is accelerating said tumbling drum through the resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and frequency sensitive by-pass means in said cylinder having by-pass port means movable with said piston for selectively establishing a second flow path of hydraulic fiuid between said opposed chambers and having valve means movable relative to said port means 96 out of phase with said piston to open said port means for bypassing the flow of hydraulic fluid in said second flow path instead of said first flow path While said rotatin means is rotating said tumbling drum at said extracting speed, said valve means including an inertia actuated valve member and resilient means for elastically supporting said inertia valve member relative to said piston in a manner to effect a natural frequency in said valve means equivalent to the vibratory frequency of said unitary system when said tumbling drum is rotated at said extracting speed.

2. In a washing machine, the combination of means forming a casing, means in said casing defining a liquid container, centrifuging means rotatably disposed in said liquid container means, means for rotating said centrifuging means about a non-vertical axis for extracting liquid from materials contained therein, said liquid container means, centrifuging means and rotating means defining a unitary system, means for elastically supporting said unitary system in said casing means for movement in a plurality of directions, said rotating means eifecting rotation of said centrifuging means from a speed below the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising a shock absorber secured between said casing means and said liquid container means, said shock absorber having a tubular means with a reciprocable piston means disposed therein dividing the tubular means into opposed chambers, the piston means having passage means therethrough for effecting a first flow path of fluid between said opposed chambers while said rotating means is rotating said centrifuging means at the resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and frequency sensitive by-pass means in said tubular means having by-pass port means movable with said piston means for selectively establishing a second flow path of fluid between said opposed chambers and having valve means movable relative to said port means out of phase with said piston means to open said port means for by-passing the flow of fluid around said passage means while said rotating means is rotating said centrifuging means at speeds above the resonant frequency of said unitary system.

3. In a Washing machine, the combination of means forming a casing, means in said casing defining a liquid container, centrifuging means rotatably disposed in said liquid container means, means for rotating said centrifuging means about a non-vertical axis for extracting liquid from materials contained therein, said liquid container means, centrifuging means and rotating means defining a unitary system, means for elastically supporting said unitary system in said casing means for movement in a plurality of directions, said rotating means effecting rotation of said centrifuging means from a speed below the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising a shock absorber secured between said casing means and said liquid container means, said shock absorber having a tubular means with a reciprocable piston means disposed therein dividing the tubular means into opposed chambers, the piston means having passage means therethrough for effecting a first flow path of fluid between said opposed chambers While said rotating means is rotating said centrifuging means at the resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and frequency sensitive by-pass means in said tubular means having by-pass port means movable with said piston means for selectively establishing a second flow path of fluid between said opposed chambers and having valve means movable relative to said port means out of phase with said piston means to open said port means for by-passing the flow of fluid around said passage means while said rotating means is rotating said centrifuging means at speeds above the resonant frequency of said unitary system, said valve means including a valve member and resilient means for elastically supporting said valve member relative to said piston means in a manner to effect a natural frequency in said valve means equivalent to the vibratory frequency of said unitary system when said centrifuging means is rotated above said resonant frequency of said unitary system.

4. The combination of claim 3 wherein said resilient means includes a pair of opposed spring supported for movement with said piston means and sandwiching said valve member therebetween in blocking engagement with said port means when said centrifuging means is rotated at the resonant frequency of said unitary system.

5. In combination, means forming a casing, means rotatably supported relative to said casing defining a container, means for rotating said container means about a non-vertical axis, said container means and rotating means defining a unitary system, means for elastically supporting said unitary system relative to said casing means for movement in a plurality of directions, said rotating means effecting rotation of said container means from a speed below the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising a shock absorber secured between said casing means and said container means, said shock absorber having a tubular means with a reciprocab1e piston means disposed therein dividing the tubular means into opposed chambers, the piston means having passage means therethrough for effecting a first flow path of fluid between said opposed chambers while said rotating means is rotating said container means at the resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and frequency sensitive by-pass means associated with said tubular means having by-pass port means movable with said piston for selectively establishing a second flow path of fluid between said opposed chambers and having valve means movable relative to said port means out of phase with said piston means to open said port means for by-passing the flow of fluid around said passage means while said rotating means is rotating said container means at speeds above the resonant frequency of said unitary system.

6. In combination, means forming a casing, means rotatably supported relative to said casing defining a container, means for rotating said container means about a non-vertical axis, said container means and rotating means defining a unitary system, means for elastically supporting said unitary system relative to said casing means for movement in a plurality of directions, said rotating means effecting rotation of said container means from a speed below the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising a shock absorber secured between said casing means and said container means, said shock absorber having a tubular means with a reciprocable piston means disposed therein dividing the tubular means into opposed chambers, the piston means having passage means therethrough for effecting a first flow path of fluid between said opposed chambers while said rotating means is rotating said container means at a resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and frequency sensitive by-pass means associated with said tubular means having by-pass port means movable with said piston for selectively establishing a second flow path of fluid between said opposed chambers and having valve means movable relative to said port means out of phase with said piston to open said port means for by-passing the flow of fluid around said passage means while said rotating means is rotating said container means at speeds above the resonant frequency of said unitary system, said valve means including a valve member and resilient means for elastically supporting said valve member relative to said piston means in a manner to effect a natural frequency in said valve means equivalent to the vibratory frequency of said unitary system when said container means is rotated above said resonant frequency of said unitary system.

7. In combination, means forming a casing, means rotatably supported relative to said casing defining a container, means for rotating said container means about a non-vertical axis, said container means and rotating means defining a unitary system, means for elastically supporting said unitary system relative to said casing means for movement in a plurality of directions, said rotating means effecting rotation of said container means from a speed at the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising an hydraulic shock absorber secured between said casing means and said container means, said hydraulic shock absorber including first means responsive to the vibrations of said unitary system at said resonant frequency for resisting the excursions of said unitary system, second means responsive to the vibrations of said unitary system at said speed above said resonant frequency for preventing the effectiveness of said first means, and resilient means elastically supporting said second means relative to said first means in a manner to effect a natural frequency in said second means equivalent to the vibratory frequency of said uni tary system when said container means is rotating at said speed above said resonant frequency.

8. In combination, means forming a casing, means rotatably supported relative to said casing defining a container, means for rotating said container means about a non-vertical axis, said container means and rotating means defining a unitary system, means for elastically supporting said unitary system relative to said casing means for movement in a plurality of directions, said rotating means effecting rotation of said container means from a speed at the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means secured between said casing means and said container means, said damping means including first means responsive to the vibrations of said unitary system at said resonant frequency for resisting said vibrations when said container means is rotating at said speed at said resonant frequency, second means responsive to the vibrations of said unitary system at said speed above said resonant frequency to negate the effectiveness of said first means, and resilient means elastically supporting at least a portion of said second means in a manner to effect a natural frequency in said portion of said second means equivalent to the vibratory frequency of said unitary system when said container means is rotating at said speed above said resonant frequency.

9. In combination, means forming a casing, means rotatably supported relative to said casing defining a container, means for rotating said container means about a non-vertical axis, said container means and rotating means defining a unitary system, means for elastically supporting said unitary system relative to said casing means for movement in a plurality of directions, said rotating means effecting rotation of said container means from a speed below the resonant frequency of the elastically supported unitary system to a speed above said resonant frequency, and damping means comprising a shock absorber secured between said casing means and said container means, said shock absorber having a tubular means with a movable piston means disposed therein dividing the tubular means into opposed chambers, the piston means having passage means 'therethrough for effecting a first flow path of fluid between said opposed chambers while said rotating means is rotating said container means at the resonant frequency of said unitary system thereby to dampen the vibrations of said unitary system, and fre quency sensitive by-pass means associated with said tubular means having by-pass port means for selectively establishing a second flow path of fluid between said opposed chambers and having valve means movable rela- 15 References Cited in the file of this patent UNITED STATES PATENTS 1,268,452 Goodyear June 4, 1918 10 2,642,996 Oeler et al. June 23, 1953 FOREIGN PATENTS 877,164 Great Britain Sept. 13, 1961 1,048,137 France July 29, 1953

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Referenced by
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US3262661 *Apr 30, 1964Jul 26, 1966Westinghouse Electric CorpDamping system for washing machines
US3297284 *Nov 6, 1964Jan 10, 1967Pellerin Corp MilnorSuspension system for machines
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US3389881 *Jul 12, 1966Jun 25, 1968Philips CorpResilient supports for rotating machine parts
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Classifications
U.S. Classification210/145, 188/314, 68/23.1, 248/610, 210/364, 248/562
International ClassificationD06F37/20, D06F37/22
Cooperative ClassificationD06F37/22
European ClassificationD06F37/22