Patent Application
20070006394
1. Field of the Invention
The invention relates generally to a multiple directional clutch for a vertical axis washing machine and more specifically to a multiple directional wrap spring clutch that enables dynamic breaking of a washing machine basket.
2. Description of the Related Art
Vertical axis washing machines typically comprise an agitator, impeller, or other clothes and/or wash liquid moving element mounted for rotation inside a perforated basket, which defines a wash chamber for holding a clothes load and is rotationally mounted inside a stationary wash tub. During a wash cycle, the clothes load is usually subjected to a wash step to wash the clothes load with wash liquid, a rinse step to rinse the wash liquid from the clothes load with water, and a spin step to extract excess rinse water from the clothes load. During the wash and rinse steps, the agitator rotates relative to the basket to move the clothes load and/or liquid within the wash chamber. During the spin step, both the agitator and the basket typically rotate at high speeds in the same direction to plaster the clothes load against the peripheral wall of the basket and thereby extract excess water from the items in the clothes load.
Rotation of the agitator and the basket is driven by a motor located in the washing machine beneath the wash tub. The agitator is fixedly mounted to an upper end of an agitator shaft that extends through the bottom of the basket, and the lower end of the agitator shaft is coupled to the motor such that the motor applies torque to the agitator shaft to induce rotation of the agitator shaft and thereby the agitator. Usually, the motor is reversible to reverse the rotational direction of the agitator according to stage of the wash cycle. Additionally, the motor dynamically brakes the agitator by reversing the torque applied to the agitator from its current rotational direction.
The basket is fixedly attached to a spin tube that surrounds the agitator shaft with upper and lower bushings therebetween. The spin tube is selectively mechanically coupled to the agitator shaft via a unidirectional clutch mechanism. When the clutch mechanism mechanically couples the spin tube to the agitator shaft, the spin tube rotates with the agitator shaft so both the basket and the agitator rotate together. Conversely, when the clutch mechanism mechanically decouples the spin tube from the agitator shaft, the agitator rotates alone while the basket remains stationary. To cease rotation of the spin tube and thereby the basket, the washing machine includes a separate mechanical brake mechanism that engages the spin tube or other component coupled to the basket when commanded to do so by a controller.
Numerous types of clutch mechanisms have been developed to accomplish transmission of rotational energy from the agitator shaft to the spin tube. One type of well-known clutch mechanism is a wrap spring clutch. Typically, a wrap spring clutch is a torsion spring disposed around the outer diameter of the spin tube and a coupler integrally formed with or otherwise fixed to the agitator shaft and axially aligned with the spin tube. Commonly, the wrap spring is wrapped around spin tube and the coupler so that in its neutral state, it is in a tightened condition around the spin tube and coupler so that it naturally mechanically couples the spin tube to the agitator shaft. When the motor/agitator shaft rotates in a first direction, the wrap spring further tightens from the neutral state to continue to couple the spin tube to the agitator shaft/coupler. Conversely, the wrap spring inherently unwinds or loosens about the spin tube and coupler when the motor reverses the torque applied to the agitator shaft, thereby resulting in the wrap spring slipping relative to the spin tube and coupler and thereby decoupling the spin tube from the agitator shaft/coupler. Thus, this type of wrap spring clutch is unidirectional as the wrap spring couples the agitator shaft and the spin tube only during rotation in one direction. Rotation of the basket is limited to rotation in only one direction, the direction that corresponds to the engagement of the clutch. Thus, it follows that when the motor is reversed to reverse the torque on the agitator shaft and brake the agitator, the wrap spring decouples the spin tube from the agitator shaft, and the spin tube and thereby the basket continue to rotate. Consequently, a separate brake that acts upon the spin tube or other component coupled to the basket is required to cease rotation of the basket. It is therefore desirable have a clutch that eliminates the need for a separate brake by coupling the motor and basket during rotation in both forward and reverse directions so that reversal of the motor brakes the basket.
A method according to one embodiment of the invention for dynamically braking a basket of an automatic washing machine comprising a spin tube coupled to the basket and an agitator shaft coupled to an agitator mounted in the basket comprises coupling the spin tube to the agitator shaft for cooperative rotation, applying a torque to the agitator shaft in a first torque direction to rotate the agitator shaft and thereby rotate the agitator and the basket, and maintaining the coupling of the spin tube and the agitator shaft while applying a torque to the agitator shaft in a second torque direction opposite the first torque direction to dynamically brake the agitator and the basket.
The applying of the torque to the agitator shaft in the first torque direction can comprise spinning the agitator shaft at a speed sufficient to extract liquid from the clothes load. The method can further comprise decoupling the spin tube from the agitator and reciprocally rotating the agitator shaft between the first and second rotation directions prior to the spinning of the agitator shaft. The method can further comprise ceasing rotation of the agitator shaft to stop the reciprocal rotation of the agitator shaft prior to the spinning of the agitator shaft.
The applying of the torque to the agitator shaft in the first torque direction can comprise driving a motor coupled to the agitator shaft. The applying of the torque to the agitator shaft in the second torque direction can comprise reversing the motor.
The coupling of the spin tube to the agitator shaft can comprise actuating a multi-directional clutch to couple the spin tube to the agitator shaft. The actuating of the multi-directional clutch can occur as a result of the applying of the torque to the agitator shaft in the first torque direction. The maintaining of the coupling of the spin tube and the agitator can comprise actuating the multi-directional clutch again to maintain the coupling of the spin tube to the agitator shaft. The actuating of the multi-directional clutch again can occur as a result of the applying of the torque to the agitator shaft in the second torque direction to dynamically brake the agitator and the basket. The actuating of the multi-directional clutch and the actuating of the multi-directional clutch again can comprise tightening a portion of a wrap spring that surrounds the agitator shaft and the spin tube. The method can further comprise decoupling the spin tube from the agitator and reciprocally rotating the agitator shaft between first and second rotation directions. The decoupling of the spin tube from the agitator shaft can comprise deactivating the multi-directional clutch to decouple the spin tube from the agitator shaft. The deactivating of the multi-directional clutch can comprise loosening the wrap spring.
The maintaining the coupling of the spin tube and the agitator shaft can occur as a result of the applying of the torque to the agitator shaft in the second torque direction.
An automatic washing machine according to another embodiment of the invention comprises a basket defining a wash chamber to hold a clothes load, a spin tube coupled to the basket for cooperative rotation with the basket, an agitator mounted for rotation within the basket, an agitator shaft coupled to the agitator for cooperative rotation with the agitator, a motor coupled to the agitator shaft for rotating the agitator shaft and the agitator in a first rotational direction and a second rotational direction opposite the first direction, and a clutch having a clutched condition wherein the spin tube is coupled to the agitator shaft for cooperative rotation regardless of the rotational direction of the agitator shaft.
The clutch can be operable between the clutched condition and an unclutched condition wherein the spin tube is not coupled to the agitator shaft. According to one embodiment, when the clutch is in the unclutched condition, the spin tube is not coupled to the agitator shaft regardless of the rotational direction of the agitator shaft.
The clutch can comprise a wrap spring surrounding at least a portion of the spin tube and at least a portion of the agitator shaft in a tightened condition when the clutch is in the clutched condition and in a loosened state when the clutch is in the unclutched condition. The wrap spring can surround an agitator shaft coupler on the agitator shaft. The automatic washing machine can further comprise a wrap spring housing that supports the wrap spring around the spin tube and the agitator shaft. The wrap spring can comprise a first end and a second end, and the wrap spring housing can comprise a retainer that holds the first end of the wrap spring and a slot that slidingly receives the second end of the wrap spring. The automatic washing machine can further comprise a clutch actuator with a retainer that holds the second end of the wrap spring slidingly received in the slot such that movement of the clutch actuator relative to the wrap spring housing moves the second end of the wrap spring within the slot to move the wrap spring between the tightened condition and the loosened state. The clutch actuator can comprise a cogwheel surrounding the wrap spring housing and having an inner diameter surface in which the retainer is formed and an outer diameter surface with cogs sized to receive an arm that moves the cogwheel relative to the wrap spring housing. The wrap spring housing can be fixed to the spin tube for cooperative rotation and can couple with the agitator shaft via the wrap spring when the clutch is in the clutched condition.
An automatic washing machine according to another embodiment of the invention comprises a basket defining a wash chamber to hold a clothes load, a spin tube coupled to the basket for cooperative rotation with the basket, an agitator mounted for rotation within the basket, an agitator shaft coupled to the agitator for cooperative rotation with the agitator, and a dynamic brake coupled to the spin tube to stop the rotation of the basket.
The dynamic brake can stop rotation of the basket regardless of a rotational direction of the basket.
The dynamic brake can comprise a motor coupled to the spin tube and operable between opposite torque directions, wherein the motor reverses its torque direction from one of the opposite torque directions to the other of the opposite torque directions to stop the rotation of the basket. The dynamic brake can further comprise a clutch having a clutched condition wherein the motor is coupled to the spin tube to rotate the basket. The clutch can couple the motor to the spin tube regardless of the torque direction of the motor.
The clutch can comprise a wrap spring that surrounds the spin tube and is coupled to the motor. The clutch can further comprise a wrap spring housing that supports the wrap spring and is fixedly coupled to the spin tube. The wrap spring can tightly surround one of the spin tube and a portion of the wrap spring housing to couple the motor to the spin tube during operation of the motor in the other of the opposite torque directions to stop the rotation of the basket.
The agitator shaft can be coupled to the motor for cooperative rotation with the motor, and the agitator shaft couples the motor to the clutch assembly. The clutch can further comprise an agitator shaft coupler coupled to the agitator shaft, and the wrap spring can tightly surround the agitator shaft coupler to couple the wrap spring to the motor.
In the drawings:
Referring now to the figures,
As discussed briefly in the background section, a typical wash cycle comprises at least a wash step to wash the clothes load with wash liquid, a rinse step to rinse the wash liquid from the clothes load with water, and a spin step to extract excess rinse water from the clothes load. During the wash and rinse steps, the agitator 22 rotates relative to the basket 18 to move the clothes load and/or liquid within the wash chamber 20. During the spin step, both the agitator 22 and the basket 18 typically rotate at high speeds in the same direction to extract excess water from the fabric items. Depending on the type of wash cycle selected by a user through the control panel 28, the clothes load can be subjected to a variety of combinations and numbers of wash, rinse, and spin steps.
Referring now to
A generally hollow spin tube 50 according to the illustrated embodiment of the invention surrounds the agitator shaft 30 with an upper bushing (not shown) and a lower bushing 56 therebetween at an upper end 52 and a lower end 54, respectively, of the spin tube 50 so that the agitator shaft 30 can rotate relative to the spin tube 50. At the upper end 52, the spin tube 50 is fixedly mounted to the basket 18 so that rotation of the spin tube 50 rotates the basket 18 in the same direction, as is well known in the washing machine art. At the lower end 54, the spin tube 50 includes an annular recess 58 formed therein to accommodate the lower bushing 56. The spin tube 50 is selectively coupled to the agitator shaft 30 for cooperative rotation by a clutch assembly 60.
As shown in section in
With continued reference to
The wrap spring 70 is held within a wrap spring housing 80 comprising a cylindrical outer wall 82 and a coaxial cylindrical inner wall 84 joined by an annular bottom wall 86. As best viewed in
Referring back to
When the clutch assembly 60 is assembled to the agitator shaft 30 and the spin tube 50, as shown in
The wrap spring 70 sits between the outer and inner walls 82, 84 of the wrap spring housing 80 with the upper tab 72 residing in the notch 100 and the lower tab 74 situated in the horizontal branch 94 of the slot 90, as best seen in
Referring back to
In operation, rotation of the pulley 36 by the motor 24 in a forward and/or a reverse direction rotates the agitator shaft 30 and the agitator shaft coupler 62 in the forward and reverse directions. To control transfer of rotational movement from the agitator shaft 30 to the spin tube 50, the clutch assembly 60 is operable between three clutched conditions (neutral clutched condition, first rotating clutched condition, and second rotating clutched condition) and an unclutched condition. When the clutch assembly 60 is in the neutral clutched condition shown in
When the agitator shaft 30 rotates in a first direction, as indicated by an arrow A in
Conversely, rotation of the agitator shaft 30 in a second, opposite direction, as indicated by an arrow B in
When the clutch assembly 60 is deactivated and moved to the unclutched condition, the wrap spring 70 moves from the tightened condition (i.e., one of the tightened and neutral states) to the loosened state to decouple the agitator shaft coupler 62 from the spin tube 50 and the wrap spring housing 80; therefore, rotation of the agitator shaft 30 in either the first or second directions does not induce rotation of the spin tube 50. To move the clutch assembly 60 to the unclutched condition, the arm 124 extends toward the cogwheel 110 to engage the teeth 112, and the arm 124 displaces the cogwheel 110 in the first direction against the natural bias of the wrap spring 70 to rotate the cogwheel 110 relative to the wrap spring housing 80. Rotation of the cogwheel 110 relative to the wrap spring housing 80 in the first direction moves the lower tab 74 of the wrap spring 70 toward the second stop 95 of the horizontal branch 94 of the slot 90, as shown in
During operation of the washing machine 10, the controller 26 commands the motor 24 to apply torque to the agitator shaft 30 in first and second torque directions, which are torque directions that can induce rotation of the agitator shaft 30 in the first and second rotational directions, and the arm 124 to move toward and to retract from the cogwheel 110 according to the step of a selected wash cycle. During steps, such as the spin step, where the agitator 22 and the basket 18 rotate together, the arm 124 remains retracted so that the clutch assembly 60 is in one of the clutched conditions or can move between the clutched conditions described above depending on the direction of rotation induced by the motor 24. During steps, such as the wash step and the rinse step, of the wash cycle where the basket 18 must remain substantially stationary while the agitator 22 rotates in at least one of the first and second directions, the arm 124 engages the cogwheel 110 to move the clutch assembly 60 to the unclutched condition, as described above.
Because the agitator 22 and the basket 18 can be coupled together while rotating in both the first and second directions during operation of the washing machine 10, reversing the motor 24 to reverse the torque applied to the agitator shaft 30 while the clutch assembly 60 is in one of the clutched conditions acts to simultaneously slow down or brake the agitator 22 and the basket 18. Thus, simple reversal of the motor 24 dynamically brakes both the agitator 22 and the basket 18 when they are operably coupled together by the clutch assembly 60, and the need for a separate friction brake for the basket 18, as in prior art washing machines, is eliminated. Elimination of the separate friction brake and replacement by a dynamic brake formed by the clutch assembly and the motor is a major advance in drive systems for vertical axis washing machines.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.
