US2986913A - Vertical-axis washing and centrifuging machine - Google Patents

Description

June 6, 1961 R. E. CONDIT ETAL VERTICAL-AXIS WASHING AND CENTRIFUGING MACHINE Filed Oct. 10, 1960 2 SheetsSheet 1 THEIR ATTORNEY June 6, 1961 R. E. CONDIT ETAL 2,986,913

VERTICAL-AXIS WASHING AND CENTRIFUGING MACHINE Filed Oct. 10, 1960 I 2 Sheets-Sheet 2 FIG-2.2

F l G. 3

LOW SPEED $P|N PAUSE. C LOW 575D SPIN E PAUSE A PAUsE B PAUSE D PAUSE OFF L WASH -5PlN l-knmsam ||C sPIN- I mu fi 1m 64 L F'L INVENTORS ROBERT E. conun- 8 :roHN a. RHODEs THEIR ATTORNEY United mtes atent fice Patented June 6, 1961 2 986 913 VERTICAL-AXIS WASllINb AND CENTRIFUGING MACHINE Robert E. 'Condit and John E. Rhodes, Louisville, Ky., assignors to General Electric Company, a corporation of New York Filed Oct. 10, 1960, Ser. No. 61,592 1 Claim. (Cl. 68-12) This invention relates to automatic clothes washing machines, and more particularly to an arrangement in vertical axis machines for preventing such machines from attaining their full spin speed when the clothes unbalance in the basket is such that provision of full speed would cause undesirable striking of the clothes basket against the liquid retaining tub within which 1t 15 nested.

A substantial amount of harm can be done, both by movement of the machine on the floor and by damage to the machine itself, if a high speed spin is allowed to take place with an unbalance large enough to cause striking of a clothes basket rotating and gyrating at high speed against a stationary part within which it is positioned. One desirable means of taking care of this problem is to provide a suspension system for the moving parts of the machine which has a low critical speed, it being understood that unbalance-caused excursions of the moving system are normally greatest at the critical speed. In this manner, when the critical speed is caused to be quite low by suitable design of the suspension systern, any striking that takes place occurs at a relatively low speed at which, because of the small degree of fre quency and small force involved, there is no damage to the machine and it is not caused to walk on the floor. By tailoring the driving mechanism of the machine so that it has the capacity to drive the basket up to high speed under normal conditions but cannot, clue to the damping effect, force it beyond critical speed when the basket strikes a stationary part at critical speed, an inherent safety check is put on the machine: it always continues through its cycle without need for safety switches of the type which shut oi the machine, and yet without any fear that damage will be done to the machine.

There is however the factor that many commercially produced machines of today are of the type in which a perforated clothes basket is closely nested within an imperforate liquid containing tub. In such a machine, the liquid level in the tub and basket is the same, and if the spinning of the basket is commenced without first emptying out the liquid, the liquid may well cushion the basket to such an extent that it will pass through critical speed without any striking occurring even though the unbalance is such that it would have caused striking if the cushioning liquid had not been present. If there is some means for causing the drain pump to operate independently of the spinning of the basket, this problem is readily overcome by pumping out the liquid prior to commencing spinning of the basket. However, a more realistic and economical form of commercially produced machines causes the drain pump to be directly connected to the motor which drives the basket so that spinning of the basket and operation of the drain pump always occur together. In such a structure it is, of course, impossible to drain the water before the basket commences to spin.

It is an object of our invention to prevent, in a machine having a perforated basket nested within an imperforate tub and having adrive mechanism in which spin and operation of the drain pump always occur together, high speed striking of the basket against the tub.

A more specific object of our invention is to achieve this goal by providing, in sequence, an intermediate spin speed during the removal of substantially all the free standing water from the tub and then after that an ac celeration through critical speed so that the critical speed of the machine will be provided without a cushion of liquid to prevent striking if it is going to occur.

In one aspect of our invention, we provide a vertical axis clothes washing machine which, in the usual manner, includes a rigid supporting frame on which spinning and washing apparatus is secured by an appropriate suspension means. The frame includes an imperforate which extends into the receptacle, torque transmitting means connected to the agitator and to the receptacle and positioned beneath them, and a reversible electric motor connected in driving relation to the torque transmitting means. In one direction of rotation of the motor, the agitator is provided with a washing movement while for the other direction of motor rotation the torque transmitting means spins the clothes receptacle. The torque transmitting means and the motor are formed to provide the receptacle with either one of two spin speeds, a lower speed for delicate garments and a higher speed for the normal articles. The suspension means and the washing and spinning apparatus are so formed that the critical speed of the machine is substantially lower than the higher rotational speed of the receptacle which may be provided by the motor and torque transmitting means, and somewhat lower than the low spin speed. A pump is directly driven by the motor and is formed so that when the motor rotates in the direction to cause spin it also causes the pump to drain the tub.

In order to prevent harmful high speed striking of the receptacle against the tub in this machine, We provide means controlling the operation of the motor which causes, in sequence, a low speed spin during removal of free-standing water from the tub, a pause to permit the basket speed to decrease through critical, and then an acceleration through critical speed to the selected speedafter the removal of substantially all the freestanding water. This insures that if the unbalance is such as to cause striking at high speed, striking will occur at the. critical speed since, as is known, the unbalance-caused excursions of the moving system are then substantially at their greatest amplitude. In combination with this structure, we proportion the driving capacity of the motor so that it is incapable of accelerating the receptacle to full speed when the damping which results from sub-- stantial striking of the receptacle against the tub occurs. In this manner, in case of excessive unbalance the full spin operation will be provided at critical speed where the striking or rubbing can do no harm to the machine. This permits the washing operation to be completed and terminated without the necessity of such costly additional items as unbalance switches.

The subject matter which we regard as our invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention itself, however, both as to its organization and method of operation maybest be understood by reference to the following description taken in conjunction with the accompanying drawings.

In the drawings,

FIGURE 1 is a side elevational view of 'a clothes washing machine of the type which may suitably include our improvement, the view being partially broken awayand partially in section toillustrate details;-

FIGURE 2 is a schematic diagram of an electrical'control circuit incorporating our invention, which circuit 18 incorporated in the machine of FIGURE 1; and

FIGURE 3 is a schematic view of a development of the cam surfaces used in the control of the timer operated switches of FIGURE 2, thereby indicating the operations of the switches by cams throughout the cycle.

Referring now to FIGURE 1, we have shown therein an agitator type clothes washing machine 1 having a conventional basket or clothes receiving receptacle 2 provided over its side and bottom walls with perforations 3 and disposed within an outer imperforate tub or casing 4. The basket 2 may be provided with a suitable clothes retaining member 5 for preventing clothes from being floated over the top of the basket, and with a balance ring 6 to help steady the basket when (as will be explained) it is rotated at high speed.

Tub 4 is rigidly mounted within an appearance cabinet 7 which includes a cover 8 hingedly mounted in the top portion 9 of the cabinet for providing access to an opening 10 to the basket 2. As shown, a gasket 11 may be provided so as to form a seal between the top of tub 4 and portion 9 of the cabinet thereby to prevent escape of moisture and moist air into the cabinet around the tub The rigid mounting of tub 4 within the cabinet 7 may be effected by any suitable means. As a typical example of one such means we have provided strap members 12, each of which is secured at one end to an inturned flange 13 of the cabinet and at its other end to the outside of tub 4. At the center of basket 2 there is positioned a vertical axis agitator 14 which includes a center post 15 and a plurality of curved Water circulating vanes 16 joined at their lower ends by an outwardly flared skirt 17.

Both the clothes basket 2 and the agitator 14 are rotatably mounted. The basket is mounted on a flange 18 of a rotatable hub 19, and the agitator 14 is mounted on a shaft (not shown) which extends upwardly through the hub 19 and through the center post 15 and is secured to the agitator so as to drive it. During the cycle of operation of the machine 1, water is introduced into the tub 4 and basket 2, and the agitator 14 is then oscillated back and forth on its axis, that is, in a horizontal plane within the basket, to wash the clothes therein. Then, after a predetermined period of this washing action, basket 2 is rotated at high speed to extract centrifugally the washing liquid from the clothes and discharge it to drain. Following this extraction operation, a supply of clean liquid is introduced into the basket for rinsing the clothes and the agitator is again oscillated. Finally, the basket is once more rotated at high speed to extract the rinse water.

The basket 2 and agitator 14' may be driven through any suitable means from a reversing motor as the specific transmission means is not a feature of'the present invention. By way of example, we have shown them as driven from a reversible motor 20- through a drive including a clutch 21 mounted onthe motor shaft. As will be more fully discussed herebelow, the motor is tailored so as to be used to its full extent when it accelerates the basket Zup to spin speed, and in order to assist this relatively light motor during its starting, clutch 21 allows the motor to start without a load and then accept the load' as it comes up to speed. A suitable belt 22 transmits power to a transmission assembly. 23 through apulley 24. Thus, depending upon the direction of; motor rotation, pulley 24 of transmission 23 is driven in. opposite directions.

Transmission clutch 21 is also a two speed clutch so as to provide for various operatingspeedsofthe machine, and inthis connection a-solenoid member25 having a plunger 26 which operates a control member 27 througha spring 28 is provided in order to achieve a two'speed operation. Specifically, in the ill-ustratedmachine, when solenoid25 is deenergized-the clutch21 provides a direct drive betweenmotor-ZO and pulley'24, andwhensolenoidZd is energizedclutch 21 provides a. reducedspeed drive-- to pulley 24. A two speed clutch of this type, particularly suited for use in the illustrated machine, is described in detail and claimed in Patent 2,869,699 issued to John Bochan on January 20, 1959 and assigned to General Electric Company, assignee of the present invention.

The transmission 23 is so arranged that it supports and drives both the agitator drive shaft and basket mounting hub 19. When motor 20 is rotated in one direction the transmission causes agitator 14 to oscillate in a substantially horizontal plane within the basket 2. Conversely, when motor 20 is driven in the opposite direction, the transmission rotates the wash basket 2 and agitator 14 together at high speed for centrifugal liquid extraction. While the specific type of drive mechanism used does not form part of the invention, reference is made to Patent 2,844,225 issued to James R. Hubbard et al. on July 22, 1958 and owned by the General Electric Company, assignee of the present invention. That patent discloses in detail the structural characteristics of a transmission assembly suitable for use in the illustrated machine.

In addition to operating the transmission 23, as described, motor 20 also provides a direct drive through a flexible coupling 29 to a pump structure, generally indicated at 30 and which may include two separate pumping units 31 and 32 both operated simultaneously in the same direction by motor 20. Pump 31 has an inlet which is connected by a conduit 33 to an opening 34 formed at the lowermost point of tub 4. Pump 31 also has an outlet which is connected by a conduit 35 to a suitable drain (not shown). The pump 32 has an inlet connected by a conduit 36 to the interior of t-ub 4 and an outlet connected by conduit 37 to a nozzle 38. The pumps are formed so that in the spin direction of rotation pump 31 will draw in liquid from opening 34 through conduit 33 and then discharge it through conduit 35 to drain, and in the other direction of rotation pump 32 will draw in liquid through conduit 36 and discharge it through conduit 37 and nozzle 38, each of the pumps being substantially inoperative in the direction of rotation in which it is not used.

Nozzle 38 is positioned to discharge into a filter pan 39 secured on the top portion 40 of agitator 14 so as to be movable therewith. With this structure, then, when the motor is rotating so as to provide agitation, pump 32 draws liquid through conduit 36 from tub 4 and discharges it through conduit 37 so that the liquid passes from nozzle 38 into filter pan 39, and then down through a number of small openings 41 provided in the bottom of the filter pan and back into basket 2. In this manner, the filter pan 39, with its small openings 41 and its upstanding side wall 42, causes lint which is separated from the clothes during the washing operation to be filtered out of the water and thus prevents it from being redeposited on the clothes. This type of structure is more fully described and claimed in Patent 2,481,979 issued to Russell H. Colley on September 13, 1949 and assigned to General Electric Company, owner of the present invention.

Themotor 20, clutch 21, transmission 23, basket 2 and agitator 14 form a suspended washing and centrifuging system which is supported by the stationary structure of the machine (which includes tub 4) so as to permit isolation of vibrations from the stationary structure; it will be understood that such vibrations occur primarily as a result of high speed spinning of basket 2 with a load of clothes therein as mentionedv above. While any suitable suspension structure which Willprovide the. desired low critical speed (to be further discussed herebelow) may be used, we prefer to use a suspension Structure which includes a bracket member 43with transmission 23 mounted on top thereof and motor 20 mounted to the underside thereof. The bracket member in turn is secured to upwardly extending rigid members 44, and each of the two upwardly extending-members 44 is'connected to a cable 45 supported'fromthe top of the'machine. While only aportion of the suspension system is-shown=inthe draw-- ing, such a vibration isolating system is fully described and claimed in application Serial No. 843,611 for Vibration Isolating System, filed on September 21, 1959 by John Bochan and assigned to General Electric Company, assignee of the present invention, reference hereby being made to that application. Such a suspension system provides for flexible support of the motor transmission, agitator and basket so as to isolate the vibrations in that system from the casing of the machine and so as to provide a low range of critical speeds.

In order to accommodate the movement which occurs between basket 2 and tub 4 without any danger of leakage between them, the stationary tub 4 is joined to the upper part of transmission 23 by a suitable flexible boot member 46. Boot 46 may be of any suitable configuration, many of which are known in the art to permit relative motion of the parts to which it is joined without leakage therebetween. A suitable and highly eflfective structure of this type is described and claimed in application Serial No. 822,493 filed on June 24, 1959, now Patent No. 2,959,966, for Joining Member For Providing a Flexible Connection Between Two Relatively Movable Members, by John Bochan and assigned to General Electric Company, assignee of the present invention.

Completing now the description of the machine as illustrated in FIGURE 1, hot and cold water may be supplied to the machine through conduits 47 and 48 which are adapted to be connected respectively to sources of hot and cold water (not shown). Conduits 47 and 48 extend into a conventional mixing valve structure 49 having solenoids 50 and 51 so that energization of solenoid 50 permits passage of hot water through the valve to a hose 52, energization of solenoid 51 permits passage of cold water through the valve, and energization of both solenoids permits mixing of hot and cold water in the valve and passage of warm water into hose 52. Hose 52 communicates with a nozzle 53 positioned to discharge into basket 2 so that when one or both of the solenoids 50 and 51 is energized water enters into basket 2 and tub 4.

The level to which the water rises in the basket and tub may be controlled by any suitable means. One typical means of doing this is to provide an opening 54 in the side of tub 4 adjacent the bottom thereof, the opening 54 being connected through a conduit 55 and a tube 56 to a conventional pressure sensitive device (shown only schematically, in FIGURE 2, by the numeral 56a) which may be positioned within the backsplasher 57 of machine 1. In the conventional manner, as the water rises in basket 2 and tub 4, it exerts increasing pressure on a column of air trapped in tube 56, and at a predetermined pressure level the column of air then trips the pressure sensitive mechanism to shut off whichever solenoids 50 and 51 may be energized. The backsplasher 57 may have suitable manual controls, such as that shown at 58, extending therefrom so that the particular type of cycle, including washing and spin speeds, water temperatures, water level within the tub 4 and basket 2, etc., may be controlled to efiect the washing of different types of fabrics.

Referring now to FIGURE 2, the electrical control system for the machine of FIGURE 1 will be described. In connection with the circuit of FIGURE 2, it will be understood that present-day washers often include various improvements such as control panel lights, bleach dispenser controls, etc., which do not relate in any way to the present invention, and that to some extent these have been omitted for the sake of simplicity and ease of understandmg.

In order to control the sequence of operation of the components of machine 1, the circuit includes a timer motor 59 which drives a plurality of cams 60, 61, 62, 63 and 64. These cams, during their rotation by the timer motor, actuate various switches (as will be described), causing the machine to pass through an appropriate cycle of operations, first washing the clothes, next extracting water from them, then rinsing the clothes in clean water,

and finally extracting the rinse water from the clothes. The operating surfaces of the ditferent cams are shown in developed form in FIGURE 3 and will be further discussed herebelow in connection with the description of the operation of the machine.

The electric circuit as a whole is energized from a power supply (not shown) through a pair of conductors 65 and 66. Cam 60 controls a switch 67 which includes contacts 68, 69 and 70. When the cam has assumed a position where all three contacts are separated, machine 1 has been disconnected from the power source and is inoperative. When operation of machine 1 is initiated, as will be explained below, switch 67 is controlled by cam 60 so that contacts 68 and 69 are engaged. When the main switch 71 is closed (by one of the controls 58), power is then provided to the control circuit of the machine from conductor 65 through contacts 68 and 69. From contact 69 the circuit extends through conductor 72 and control solenoid 50 to a manually operable switch 73; also, from conductor 72, a circuit extends through control solenoid 51 to a manually operable switch 74. In

addition, a circuit is completed from conductor 72 through solenoids 50 and 51 to a pair of stationary contacts 75 and 76 respectively, these two contacts forming a part of a switch 77 controlled by a cam having a movable contact 78 controlled by cam 61. When contact 78 is in its up position engaging contact 76, it completes a connection through solenoid 51 to conductor 79, and when contact 78 is in its down position engaging contact 75, it completes a connection through solenoid 50 to the conductor 79. It will thus be seen that when switches 73 and 74 are open, euergization of solenoids S0 and 51 is under the control of switch 77. When switch 73 is closed, the hot water solenoid is energized independently of the position of switch 77, and when switch 74 is closed the cold water solenoid is energized independently of the position of switch 77 From the hot and cold water solenoids the energizing circuit thus extends through conductor 79, and then through a coil 80 of a relay 81, the main winding 82 of motor 20, a conventional motor protector 83, a conductor 84, a switch 85 controlled by cam 63, switch 71, and the conductor 66.

The motor 20 is of the conventional type which is provided with a start winding 86 which assists the main winding 82 during the starting of the motor and is energized in parallel therewith. When a relatively high current passes through the relay coil 80 it causes the relay contact 87 to be closed; thus permits an energizing circuit for the start winding to be completed in parallel with the main winding through a contact 88 of a switch generally indicated at 89 and which is controlled by cam 62, contact arm 90, the relay contact 87, the start winding 86, contact arm 91, and contact 92 of switch 8 9. A circuit is also completed in parallel with motor 20 from conductor 79 through the timer motor 59.

The relay coil 80 is designed to close contact 87 when a relatively high current, of the level demanded by the motor when the rotor is rotating below a predetermined speed, is passing through it. At other times, when there is no current passing through the relay coil 80 or when the current is below the required energizing level as is true in the running speed range of the motor, the contact 87 is open.

When the main winding 82 of motor 20 is in series with the valve solenoids 50 and 51 as described, a much lower impedance is presented in the circuit by the motor 20 than is presented by the valve solenoids. As a result, the greater portion of the supply voltage is taken up across the solenoids and relatively little across the motor. This causes whichever of the solenoids which is connected in the circuit to be energized sufliciently to open its asso-. ciated water valve. -As a result, water at a suitable tem perature is admitted to the machine through outlet-53, motors 26 and 59 remaining inactive.

This action continues, with the circuitry thus arranged, so that the water pours into the basket 2 and tub 4. Because of the perforations 3, the water rises ih both basket and tub at the same rate. As the head of water acting on the column of air trapped in tube 56 increases, the pressure of this air increases until it actuates the pressure sensitive switch 56a provided within backsplasher 57. When switch 56a closes, it then provides a short circuit across the solenoids directly from conductor 72 to conductor 79 so that, with the solenoids thus excluded from the effective circuit, they become deenergized and a high potential drop is provided across winding 82 of the motor 20. This causes the relay coil 80 to close contact 87 to start the motor 20, while at the same time timing motor 59 starts so as to initiate a sequence of operations.

Completing the description of the circuit of FIGURE 2 prior to describing in full its operation, it is to be observed that the switch 85 is in series with the main motor 26 but is not in series with the timing motor 59. Thus, by the opening of this switch, the operation of motor is stopped. The timer motor will nonetheless continue to operate, as a result of the fact that the timer motor 59 is deliberately provided with an impedance much greater than that of the valve solenoids so that it will take up most of the supplied voltage and will continue in operation, leaving so little voltage across the solenoids that they do not operate their respective valves.

A further point of the circuit of FIGURE 2 is that when switch arms 99 and 91 are moved by cam 62 to engage contact 92 and a contact 94 respectively, the polarity of the start winding is reversed. The circuit from conductor 79 then proceeds through contact 94, contact arm 91, the start winding 86, relay contact 87, contact arm 90, and contact 92 to the protective device 83 and conductor 84. Thus, provided motor 20 is stopped or slowed down so that relay contact 87 is closed, the reversal of switch S9 is efiective to cause the motor 20 to rotate in the opposite direction than that previously provided once the motor is started up again.

In order to energize the motor 20 independently of the water level switch 56a and the valve solenoids when spin is to be provided, cam 69 is formed so that it may cause all three contacts 68, 69 and 70 of switch 67 to be closed during the extraction or spin step. This causes the power to be supplied directly through contact 70 to conductor 79 and the motors, rather than through the water level switch or the valve solenoids.

In order to attain maximum washing effectiveness for diiferent types of loads, operation of the agitator mechanism during washing and rinsing steps may be provided either at high speed or low speed, and the spin speed of the basket during spinning may also be selected as either high or low. As stated above, solenoid is provided in connection with clutch 21 in order to achieve the two output speeds of the clutch to provide for high and low speed agitation and high and low speed spin operations. A manually operable switch 95 controls the agitation speed, and a manually operable switch 96 controls the spin speed provided the contacts 97 and 98 of a switch 99 controlled by a cam 64 are in the position shown. When switch 95 is connected to contact 190 and conductor 101, solenoid 25 is not energized during agitation and consequently high speed agitation is provided; when switch member 95 engages contact 192 and conductor 84, the solenoid is energized during agitation and low speed agitation is provided. in the same manner, connection of switch 96 with contact 193 and conductor 191 prevents energization of solenoid 25 during spin and a high speed spin is provided, while connection of switch arm 96 to contact 104 causes energization of solenoid 25 during spin and a low spin speed is provided. The precise mannor in which the setting of the switches 95 and 96 controls the" energizatign of solenoid 25 is described in substantial detail-and is claimed in Patent 2,950,612 issued on August 30, 1960 to"Wallace Hi Hensha'w, and-assigned to General Electric Company, owner of the present invention.

As the means of providing the important speed con-' trolling feature of our invention, we provide the switch 99 which has the contacts 97 and 98 as previously mentioned. Contact 97 is in series with the manually operable switch 96 and thus controls the effectiveness of switch 96. When contact 97 is completing a circuit to switch 96, contact 98 is opening a circuit which, by means of a conductor 105, constitutes a path in parallel with switch 96 to conductor 79. When the switch 99 is moved by cam 64 so that contact 97 disconnects switch 96, contact 98 is then in position to complete a circuit through conductor 105 from the solenoid 25 to conductor 79, and as explained this is effective to cause a slow spin to be provided.

Referring now to FIGURE 3 in conjunction with FIGURE 2, a sequence of operation of the machine 1 will be described. It will be assumed that the timer has been set at WASH so that cam 64} has caused contacts 68 and 69 to be closed, cam 61 has caused contact 78 to engage contact '75, cam 62 has positioned switch 89 as shown, cam 63 has closed switch 85, and cam 64 has moved switch 99 to the position shown. At this point the first step which takes place is the filling of the machine with water by the energization of the solenoids and the consequent inactive status of motors 20 and 59 as previously explained. As also previously explained the filling continues until the closure of switch 56a at which point the solenoid or solenoids are deenergized and consequently motors 20 and 59 are energized, the energizetion of motor 20 being in the direction to cause an agitation operation which, with manual switch 95 in the position shown, will be at the higher of the two available speeds.

This washing action continues for a predetermined time until pause A is reached, at which time cam 63 opens switch This stops the operation of motor 20 and consequently there is no further agitation although, as explained, the timer continues to operate. During pause A cam 60 moves to its spin position in which it closes all three contacts 68, 69 and 70, cam 62 reverses switch 89, and cam 64 moves contacts 97 and 98 to their open and closed positions respectively.

As a result of this, when at the end of pause A i switch 85 is reclosed by cam 63, motor 20 is energiied once again (by virtue of the bypassing of solenoids 50 and 51 by switch 67) but in the opposite direction. As explained, this causes spinning of basket 2 and also operation of pump 31 to pump out liquid from tub 4 to the by the contact 98 and conductor 105. Thus, a low speed spin is commenced regardless of what kind of spinning operation was initially selected. Of course, the'pumping rate is unatiected since the motor continues to operate at the same speed and the pumping rate is dependent only upon operation of the motor.

, This continues for a brief period of time; one minute, for example, has been proven to be entirely suflicient for pump 31 to remove substantially all freestanding water from tub 4 in the machine described so that the water does not have a cushioning effect on the unbalance-caused movement of basket 2. At the end of this brief period of time, cam '63 opens switch 85 so that the motor 20 is deenergized and the spinning of basket 2 ceases. During the resulting pause, basket 2 slows down below the critical speed and cam 64 moves contacts 98 and 97 back into the position shown in FIGURE 2 so that the position of switch 96 once again controls the spin speed. I

Thereafter at the end of the pause B, the cam 63 recloses switch 85 and a spin operation is recommenced. This time; of" course, with'the water having already been puniped ont; the" critical s'p'edof rot'atioi'i er basket 2' is reached with substantially no freestanding water in the tub 4. As a result, in view of the fact that unbalancecaused excursions of basket 2 are substantially at a maximum at the critical speed, if the unbalances are great enough to cause a striking or rubbing of basket 2 against the inner wall of tub 4, it will occur at the relatively low speed which the appropriate design of the suspension system permits to be provided as the critical speed for the system.

It will be recognized that a substantial amount of damping, that is, dissipation of energy, will result from striking or rubbing of the basket 2 against the tub 4 as a result of unbalance-caused excursions. The damping efiect provided by the rubbing of basket 2 against tub 4 is so calibrated relative to the load capacity of clutch 21 that the amount of damping provided prevents the motor 20 from increasing the basket speed past critical if any substantial amount of striking or rubbing of the basket and the tub is occurring. As a result, in the event of excessive unbalance, the full first spin operation, as shown in FIGURE 3, will take place substantially at the critical speed which is so low that the rubbing or striking does not cause any ill effect to the machine. However, if the unbalances in the machine were small enough to allow high speed operation without striking, then the machine will go through the critical speed rotation of basket 2 without striking occurring. When this happens, the motor 20 has suflicient capacity to raise the basket speed to the full desired value, generally on the order of several hundred r.p.m., that is, substantially more than the critical speed.

In either event, the spin operation will continue until pause C, at which time switch 85 is again opened by cam 63, cam 60 disconnects contact 70, cam 62 reverses the start Winding connections, and cam 61 moves switch 78 into engagement with contact 76. When the pause C is ended by the closing of switch 85, one or both of solenoids 56 and 51 are energized in the same manner as previously, the only difierence being that if both switches 73 and 74 are open the cold water solenoid 51 will be energized instead of the hot water solenoid 50 which was previously energized. In this manner, the basket will be filled with cold water, and when the proper level has been reached the motors 59 and 20 will start to provide a timed rinse operation.

After the rinse, a fourth pause D is provided during which the timer-operated switches, with the exception of switch 77, are positioned in the same manner as they were during pause A." Thereafter, the same sequence of a low speed spin, then another pause E, and then an acceleration through the critical speed without a substantial amount of water being present in the tub 4 are provided. At the end of the second full spin, the machine is turned off with the clothes in a clean rinsed condition and damp dried by the centrifugal force of the last spin.

It will be seen that our invention provides a means of avoiding damage to the machine by high speed striking, while at the same time avoiding the substantial added expense of either a neutral in the transmission or an unbalance switch.

It will be understood that while in accordance with the patent statutes we have described what at present is considered to be the preferred embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made herein without departing from our invention, and it is therefore aimed in the appended claim to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

A vertical axis clothes washing machine comprising: a rigid supporting frame, washing and spinning apparatus, and suspension means securing said apparatus on said frame in vibration isolating relation thereto; said frame including an imperforate liquid receiving tub; said washing and spinning apparatus including a perforated clothes receptacle nested within said tub, movably mounted agitator means extending into said receptacle, driving means including a reversible electric motor, said driving means being connected to said receptacle and said agitator means in said receptacle and positioned therebelow, said driving means providing said agitator means with a washing movement for one direction of motor rotation and spinning said receptacle for the other direction of motor rotation, said driving means being formed to provide said receptacle alternatively with either one of two spin speeds in said other direction of motor rotation; said suspension means and said apparatus being formed so that said apparatus has a critical speed lower than either of said rotational speeds provided by said driving means to said receptacle; pump means connected to said tub and directly driven by said motor, said motor causing said pump means to drain said tub during rotation in said other direction; means controlling operation of said driving means including manually operable means for selecting one of said spin speeds, said controlling means providing in sequence the lower of said spin speeds during removal of substantially all free-standing water from said tub independently of the selection made by said manually operable means, a decrease in basket speed below critical speed, and then acceleration through critical speed to the selected speed after such removal; the capacity of said driving means being so limited as to prevent acceleration to full speed in response to striking and rubbing of said receptacle within said tub at critical speed.

References Cited in the file of this patent UNITED STATES PATENTS 2,760,639 Haverstock Aug. 28, 1956 2,859,877 Sisson Nov. 11, 1958 2,869,699 Bochan Jan. 20, 1959 2,875,526 Engel et a1. Mar. 3, 1959 2,950,612 Henshaw Aug. 30, 1960

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