"DRIVING ARRANGEMENT FOR A LAUNDRY MACHINE" Field of the Invention

The present invention refers to a driving arrangement for a laundry machine of the type comprising a structure in which is affixed a vertical cylindrical tub dimensioned to contain a load of washing liquid and in whose interior is mounted a perforated basket, generally cylindrical designed to receive the clothes to be washed, vertically and rotatively mounted in the machine structure by means of a tubular shaft and housing an impeller mounted to the upper end of a vertical central shaft, rotatively mounted in the tubular shaft and which is coupled to a motor unit responsible for the selective rotary drive of both the impeller and the basket in different steps of the machine operation. Background of the Invention

In the laundry machines of the type mentioned above, the washing operations of the clothes contained in the basket are carried out by rotation of the impeller, generally in two opposite directions by a certain number of turns and at a certain given speed, taking into account the movement to be imparted to both the clothes and the washing liquid, in order to obtain a desired washing efficiency, as well as the wear to be imposed to the clothes due to the movement to which said clothes are submitted.

Such machines further allow a spinning operation to be carried out to extract the water from the clothes, when the basket and the impeller have their shafts coupled and rotated in the same direction, at a rotation that may be equal or superior to that applied to the impeller in the washing operations. In these known machines, the basket usually requires to be locked, so as not to rotate in relation to both

the tub and the machine structure during the washing operation, in which the impeller is caused to rotate in one or in the opposite direction to move the washing liquid and the clothes immersed therein. For this purpose, there are known electromagnetic locking devices, which are automatically driven to keep the basket locked to the structure during washing and to release it to rotate during spinning. Besides this basket locking device, these machines also require a coupling device, generally also electromagnetic, for connecting the tubular shaft of the basket to the central shaft of the impeller, so that said basket can rotate jointly with the impeller during the spinning operation of the clothes. The use of two electromagnetic locking devices, one for coupling the basket to the structure and the other for coupling the basket to the impeller, is also a factor that increases the final cost of the machine. Even in the case of using a unidirectional locking device of the wrap spring type between the basket and the structure, it is necessary to lock the basket in the opposite direction through other means, such as for example a unidirectional engaging bearing, which is also a cost-increasing element. The basket, by not being rotatively locked to the structure in neither rotation direction of the impeller, is caused to rotate jointly with the impeller by action of the drag made by both the washing liquid and the clothes. In this situation, the washing liquid rotates in an increasing speed, creating a vortex and increasing its volume, until possibly flowing over the upper edge of the tub. To comply with the requirements regarding cost reduction of the machine and the operational conditions, which are necessary to achieve an

efficient washing without causing excessive wear to the clothes, is one of the problems to be solved in the known laundry machines .

Aiming at eliminating the disadvantages and deficiencies of the machines, a solution disclosed in Brazilian patent application PI0204385-8 has been proposed by the same applicant, according to which the central shaft of the impeller is alternatively and rotatively driven by the motor, in a first rotation direction, during the first rotation time, and in a second rotation direction during a second rotation time, which is substantially shorter than the first rotation time, during a washing operation of the machine, the tubular shaft of the basket being constantly and rotatively locked in relation to the structure in said first rotation direction and maintained rotatively free in the second rotation direction, said basket having its tubular shaft rotatively locked to the central shaft of the impeller when the latter is driven by the motor in the second rotation direction, upon a spinning operation of the machine .

In said previous solution of the same applicant, the locking of the tubular shaft to the machine structure is made in a simple way and in a single direction manner through a locking device of the wrap spring type, using a first spring which assures the locking of the basket against rotation in said first direction in any step of the machine operation, the basket remaining free to rotate in said second direction during the washing step and jointly with the impeller in the same second direction upon the spinning step. The control of the free rotation of the basket in the second direction in the washing step is made by limitation of time.

On the other hand, in order to couple the tubular shaft of the basket to the central shaft of the impeller during the spinning step, the solution proposed in BR PI0204385-8 uses a coupling device comprising a second helical spring mounted around an axial extension of the tubular shaft and which has a first end attached to the central shaft and a second end attached to a cylindrical sleeve that is rotatively mounted in the structure around the second spring, said cylindrical sleeve rotating jointly with said spring and the central shaft. A brake band is tightly mounted around the cylindrical sleeve and designed to have its rotation selectively blocked during the spinning operation, reducing the rotation of the cylindrical sleeve and thus promoting the tightening of the second spring around the tubular shaft, coupling it rotatively to the central shaft and allowing the basket to rotate jointly with the impeller in the spinning operation. In this prior construction, an electromagnetic device

(solenoid) secured to the structure is energized during the spinning operation, so that its actuating pin blocks the rotation of the brake band jointly with the cylindrical sleeve, so that the latter promotes the tightening of the second spring around the tubular shaft of the basket .

Although assuring a correct and automatic operation of the laundry machine at an acceptable cost, this prior art solution still presents a characteristic that needs to be improved, due to the fact that in the spinning operation the electromagnetic device must remain energized, so as to lock the rotation of the brake band around the cylindrical sleeve, with a force sufficient to assure the frictional tightness of the second spring around the tubular shaft. Moreover,

during the spinning, the brake band remains in a wearing frictional contact with the cylindrical sleeve in a region that is susceptible to the presence of oil, impairing the coupling. Summary of the Invention

Due to the deficiency commented above, it is an object of the present invention to provide a driving arrangement for a laundry machine of the type discussed above, presenting a simple constructive solution with a relatively reduced cost and which may assure an efficient coupling between the central shaft of the impeller and the tubular shaft of the basket in the spinning operation, without being subject to premature wear and to the negative effects of the presence of oil in the coupling region.

The objective mentioned above is attained by a driving arrangement for a laundry machine of the type that comprises a tub attached to a structure; a basket disposed in the interior of the tub; a vertical tubular shaft inferiorly and rotatively mounted in the structure and which has a lower end and an upper end affixed to the basket; a central shaft rotatively mounted in the interior of the tubular shaft and having an upper end inside the basket and carrying an impeller, and a lower end rotatively coupled to a motor unit attached to the structure .

According to the present invention, the driving arrangement comprises a helical spring tightly mounted around the axially adjacent extensions of both the tubular shaft and the central shaft, rotatively coupling them upon rotation of the central shaft, in one direction, in a spinning operation of the machine; a cylindrical sleeve rotatively mounted in the structure around the helical spring and being rotatively affixed to a lower end of the latter; a

brake band tightly mounted around the cylindrical sleeve and having an inoperative condition, in which it releases the cylindrical sleeve to rotate jointly with the helical spring and with the central and tubular shafts, in said direction, in the spinning operation, and an operative condition, in which its rotation is blocked in said direction, braking and interrupting the rotation of both the tubular sleeve and the helical spring in said rotation direction and radially opening the helical spring, so as to rotatively disengage the tubular and central shafts,- and an actuating device mounted to the structure and which is selectively driven from a rest position, in which it conducts the brake band to the operative condition, to a driven position, in which the brake band is conducted to the inoperative condition. With the construction cited above, the tubular and central shafts remain usually coupled to each other through the helical spring in its rest operational condition, around said shafts and connected to the cylindrical sleeve, which remains free to rotate jointly with the spring and the two shafts in the spinning operation, when the actuating device remains in the driven position, in order to release the rotation of the brake band jointly with the cylindrical sleeve. Thus, in order to couple the shafts, only the tightening force of the helical spring is used. In the washing operation, the actuating device is kept in the rest position, in which it maintains the brake band in the operative condition, with its rotation blocked by the actuating device, making the cylindrical sleeve brake, interrupting its rotation and opening the helical spring in relation to the central shaft and, in a lesser extent, to the tubular shaft, remaining

stationary jointly with the cylindrical sleeve. In this condition, there is no frictional sliding between the brake band and the cylindrical sleeve. Brief Description of the Drawings The invention will be described below, with reference to the enclosed drawings, given by way of example of an embodiment of the invention and in which: Figure 1 is a schematic diametrical vertical sectional view of a laundry machine of the type considered herein;

Figure 2 is a simplified enlarged diametrical sectional view of the region in which the impeller and the basket are rotatively mounted, and in which is mounted a device for automatically locking, in one direction, said basket in relation to the structure of the laundry machine and in which is also mounted a clutch means for promoting a relative rotational coupling between the central shaft of the impeller and the tubular shaft of the basket during the spinning operation;

Figure 3 is a perspective view of a brake band mounted around a cylindrical sleeve, in which interior the helical spring is mounted; and

Figure 4 is an enlarged cross-sectional view of the region in which the central shaft of the impeller and the tubular shaft of the basket are rotatively coupled, taken according to line IV-IV in figure 2 and illustrating the actuating device in the rest, de- energized condition. Description of the Invention

As illustrated in figure 1, the present invention is applied to a laundry machine of the type which comprises a structure E generally defining a prismatic cabinet within which is affixed, by any adequate means, a vertical and generally cylindrical tub 10,

which is inferiority closed by a bottom wall 11, superiorly opened, and dimensioned to contain a load of washing liquid. It should be understood that the tub 10 may be constructed to define, itself, the upper portion of the structure E.

Inside the tub 10 there is coaxially mounted a perforated and also generally cylindrical basket 20, which is provided with a bottom wall 21, superiorly opened and designed to contain the clothes to be washed, said bottom wall 21 being centrally attached to the upper end 30b of a tubular shaft 30, vertically projecting downwardly and outwardly from the tub 10 to be supported by a pair of bearings 31, 32 mounted to a bearing support 12 which is affixed to the bottom wall 11 of the tub 10 or incorporated to said bottom wall 11 in a single piece. This assembly of the basket 20 allows it to rotate freely around its longitudinal axis seated on the tubular shaft 30. The passage of the tubular shaft 30 through the bottom wall 11 of the tub 10 is made with the aid of a retainer 13 mounted to said bottom wall 11. Inside the tubular shaft 30, a central shaft 40 is rotatively mounted generally by means of bushings 41, 42, and to the upper end 40b of said central shaft is affixed an impeller 50 in the form of a disk positioned on the bottom wall 21 of the basket 20, maintaining from said bottom wall 21 a small axial spacing. The lower end 40a of the central shaft 40 projects outwardly from the tubular shaft 30 to receive a driven pulley 43, which is operatively coupled, by means of a belt 44, to a drive pulley 45 affixed to the shaft of an electric motor 60 mounted to the structure E of the machine, usually by being generally directly or indirectly affixed to the bottom wall 11

of the tub 10. The fixation of the drive pulley 45 to the shaft of the motor 60 can be made by interference, using grooves produced in said shaft, in order to assure the fixation and the transmission of torque therebetween, with no need of using additional fixation elements, such as nuts, for example. This construction leads to a driving arrangement and transmission that are very simple and present a relatively reduced cost as compared to the driving arrangements with variable speed and the transmissions in which the speed variation is automatically controlled as a function of the required operation. According to an aspect of the invention, which is illustratively exemplified in figure 2, the laundry machine comprises a locking device 70 for locking the tubular shaft 30 in relation to the structure E, more specifically in relation to the bearing support 12, in a single rotation direction of said tubular shaft 30. In a preferred constructive form of the invention, the locking device 70 comprises a helical spring 71, which is mounted around the tubular shaft 30, so as to slidingly seat around the latter when the locking device 70 is in an inoperative condition, said helical spring 71 having an end 72 projecting radially outwardly, in order to remain constantly fitted and locked in a housing 15 provided in the bearing support 12.

This construction provides an extremely simple and inexpensive locking of the basket in a first rotation direction, but it does not promote any locking in the opposite direction.

Thus, when the machine is working in the washing condition, the impeller 50 is rotated in the first direction for a certain time, tending to make the basket 20 rotate in the same direction. However, the

locking device 70 prevents the basket 20 from rotating in said first direction and consequently avoids the formation of a vortex by the joint displacement of the washing liquid, load of clothes, basket 20 and impeller 50.

Nevertheless, when the impeller 50 has its rotation interrupted and inverted to a second direction opposite to the first one, the basket 20 is forced by the washing liquid to rotate also in the same speed and in said second direction, in which no locking occurs relative the basket 20.

In order to prevent the level of the washing liquid from rising excessively with the rotational acceleration of the basket 20, the invention provides a specific operational procedure which is to produce an asymmetry in the rotation times of the impeller 50 in said two directions .

Since the basket 20 is conducted to rotate freely in said second rotation direction, which tends to increase the level of the washing liquid by formation of a vortex inside the basket 20, the drive of the impeller 50 in this second rotation direction is effected by a second rotation time substantially lower than the first rotation time. It should be understood that the locking device 70 described and illustrated herein is merely exemplary, since the present driving arrangement can be used jointly with other constructive solutions for locking the tubular shaft of the basket in the washing operation.

In order to allow the basket 20 to rotate with the impeller 50 in the second rotation direction during the spinning operation, the machine is provided with a driving arrangement that comprises a generally electromagnetic clutch means C, which is operatively

associated with both the tubular shaft 30 and the central shaft 40.

In the exemplary construction illustrated in figure 2, the clutch means C comprises a helical spring 80 which constitutes a second helical spring in the driving means of the machine, said helical spring 80 being tightly mounted around axially adjacent extensions of the tubular shaft 30 and the central shaft 40, the dimensioning of the helical spring 80 being carried out so as to assure, when in a normal rest condition, the safe rotational coupling between the central shaft 40 and the tubular shaft 30 in a rotation direction corresponding to the direction of a spinning operation of the machine. Thus, whenever the machine performs a spinning operation, the helical spring 80 is maintained tightly seated around both the tubular shaft 30 and the central shaft 40, making said shafts to rotate jointly in said spinning direction, which is opposite to that in which the locking device 70 operates to lock the tubular shaft 30 of the basket 20 to the structure E of the machine, preventing the basket from rotating in the other rotation direction denominated as the first rotation direction in the present disclosure. The driving arrangement further comprises a cylindrical sleeve 90, constructed in any adequate material, such as for example synthetic material, which is rotatively affixed in the structure E around the helical spring 80, maintaining a certain radial gap in relation to the latter and being rotatively affixed to a lower end 81 of the helical spring 80. In the illustrated construction, the helical end 81 of the helical spring 80 is radially bent outwardly and inserted in a corresponding radial bore made in the cylindrical sleeve 90, assuring the rotational locking

between the helical spring 80 and the cylindrical sleeve 90, but allowing a certain radial displacement of the lower end 81 of the helical spring 80 inside the radial bore of the cylindrical sleeve 90. With this arrangement, the helical spring 80 can be radially moved, maintaining its lower end 81 coupled to the cylindrical sleeve 90.

Around the cylindrical sleeve 90 is mounted a brake band 95 constructed in any adequate material and generally having an end 95a radially projecting away from the cylindrical sleeve 90, so as to selectively cooperate with an actuating device 100, to be described ahead, in order to assume an inoperative condition, in which the cylindrical sleeve 90 is released to rotate jointly with the helical spring 80 and with both the tubular and central shafts 30,40 in said rotation direction during the spinning operation, and an operative condition, in which its rotation is blocked in said direction, braking and interrupting the rotation of the cylindrical sleeve 90 and of the helical spring 80 in said rotation direction. When the cylindrical sleeve 90 is locked by the brake band 95, the helical spring 80 is also rotatively locked, whereby, when the central shaft 40 starts its rotation in the spinning direction, said helical spring 80 is opened in the radial direction, loosening its frictional contact not only with the central shaft 40 but also, generally in a lesser extent, in relation to the lower end 30a of the tubular shaft 30, allowing the central shaft 40 to rotate freely inside the tubular shaft 30, carrying only the impeller 50, while the helical spring 80 and the cylindrical sleeve 90 remain stationary as a function of the actuation of the brake band 95. The brake band 95 has its end 95a selectively blocked

by an actuating device 100 mounted in the structure E and which is driven from a rest position, in which it conducts the brake band 95 to the operative condition, towards a driven position, in which the brake band 95 is conducted to the inoperative condition.

In the preferred illustrated construction, the actuating device 100 comprises an electromagnetic actuator (solenoid) provided with an actuating pin 101, which is constantly forced by a return spring 102, to the rest condition of the actuating device 100, in which the actuating pin 101 blocks the rotation of the brake band 95, more specifically by blocking the rotation of said end 95a thereof, braking and interrupting the rotation of the cylindrical sleeve 90 and, consequently, of the helical spring 80, producing the radial opening of the latter and disengaging the central shaft 40 of the impeller 50 from the tubular shaft 30 of the basket 20. The construction described above allows, in the rest condition of the actuating device 100, its return spring 102 to maintain the actuating pin 101 in a position in which it interferes with the rotation of the end 95a of the brake band 90, disengaging the central shaft 40 and the tubular shaft 30, which disengagement is necessary for carrying out the washing operation of the machine .

During the spinning operation, the actuating device 100 is automatically energized to retain its actuating pin 101 displaced from the rest position, in which it interferes with the rotation of the brake band 95, to the operative position, that is to say, to a driven and retracted position, in which said actuating pin stops actuating onto the brake band 95, which assumes the inoperative condition, in which it rotates jointly with the cylindrical sleeve 90, and allowing the

helical spring 80 to remain in its rest condition, in which it is kept tightly mounted around the tubular shaft 30 and the central shaft 40, maintaining them mutually coupled for performing the spinning operation of the machine.

As it can be noted, upon energization of the electromagnetic actuating device 100, the electromagnetic force is sufficient to retract the actuating pin 101 against the constant action of the return spring 102, which is dimensioned to produce the displacement of the actuating pin 101 to the rest position, when the electromagnetic actuating device 100 is deenergized. The electromagnetic actuating device 100 is usually automatically deenergized when the laundry machine begins to perform the washing operations, in which the central shaft 40 and the impeller 50 are driven by the motor 60 in a condition in which the tubular shaft 30 is disengaged from the basket 20. As already mentioned above, the deenergization of the electromagnetic actuating device 100 makes the return spring 102 impel the actuating pin 101 to the rest position, in which said actuating pin interferes with the brake band 95, so as to block the rotation of the latter and also of the helical spring 80 coupled thereto, opening the helical spring 80 and disengaging the tubular and central shafts 30,40 during the washing operation. Still in accordance with the illustrated construction, the central shaft 40 incorporates an adjacent cylindrical widening 46 external to the lower end 30a of the tubular shaft 30 and presenting an outer diameter substantially equal to the outer diameter of said lower end 30a of the tubular shaft 30. This construction allows said lower end 30a of the tubular

shaft 30 and said cylindrical widening 46 of the central shaft 40 to define the axially adjacent extensions of both shafts, around which the helical spring 80 is mounted, which is preferably constructed with substantially a single diameter along its axial extension, so as to simultaneously tighten both shafts upon the spinning operation of the machine. While only one embodiment of the invention has been illustrated herein, it should be understood that alterations can be made in the form and relative arrangement of the elements, without departing from the constructive concept defined in the appended claims .