WO1996006968A1

WO1996006968A1 - Clothes washer having an improved brake system

Info

Publication number: WO1996006968A1
Application number: PCT/US1995/010980
Authority: WO
Inventors: Weston L. Schultz; Karlis I. Racenis
Original assignee: ACT INNOVATIONS Inc
Current assignee: ACT INNOVATIONS Inc
Priority date: 1994-09-01
Filing date: 1995-08-30
Publication date: 1996-03-07
Anticipated expiration: 1997-03-01
Also published as: CA2156119A1; AU3498595A

Abstract

A clothes washing machine (10) having a normally engaged disk brake (30) which is driven to a disengaged position by a ball ramp (45) when a drive motor (22) is reversed is disclosed. The disk brake (30) is biased to the engaged condition by a spring (52) or by gravitational force.

Description

-CLOTHES WASHER HAVING AN IMPROVED BRAKE SYSTEM-

Technical Field

This invention relates to a clothes washing machine having an improved brake system. More particu¬ larly, this invention relates to a washing machine having a disk brake system which is effective to auto¬ matically stop the basket during the spin cycle.

Background Art

Clothes washing machines have wash, rinse and spin cycles which are controlled by the washing machine to clean various fabrics. Most currently available washing machines have one or more preset washing cycles wherein clothing is immersed in water, agitated in a solution of soap and water, rinsed and centrifuged to remove water. During the spin cycle, the basket con¬ taining the clothing is rapidly rotated to centrifugally extract water from the clothing. Industry standards for washing machines mandate that the rapid rotation of the basket during the spin cycle must stop within a prede¬ termined period of time if the washing machine lid is opened.

To meet these standards, expensive and complex braking systems have been developed.

One example of a prior art brake system is described in U.S. Patent No. 4,165,624 which discloses a clothes washing machine having a shifter mechanism which axially shifts the driving gear and clutch into and out of engagement along the agitator shaft. This system relies upon a solenoid actuated drive pin and a load augmenting spring to provide adequate braking. The system is very complex and relatively costly.

Another example of an automatic washer basket brake mechanism is disclosed in U.S. Patent No. 4,254,641 wherein an automatic brake mechanism is disclosed which is functional even if power is inter- rupted to the machine. The brake includes brake shoes which are applied by a spring and released by a rotating cam mechanism. This approach to providing a "fail-safe" brake is a complex device requiring spring biased braking elements and complicated camming mechanism to brake the basket during the spin cycle.

Summary OfThe Invention

According to the present invention, a clothes washing machine having an improved brake system which is engaged upon termination of the spin function and grounds the transmission when the washing machine is in any mode other than the spin mode. The clothes washing machine has a drivetrain base and a wash tub fixedly mounted on the drivetrain base. A perforate basket con¬ taining the clothing to be washed is disposed within the wash tub and is secured to a drivetrain. An agitator is also secured to the drivetrain and disposed within the perforate basket. A motor provides a reversible rotary input to a driveshaft of the drivetrain. A transmis¬ sion, one-way clutch, and brake assembly are also provided as part of the drivetrain. The brake assembly comprises a rotatable disk and a grounding surface which is held stationary relative to the drivetrain base. The disk and grounding surface are axially shiftable rela¬ tive to each other. A ball ramp is provided for con¬ trolling axial and rotational movement of the disk relative to the grounding surface.

In one embodiment, a spring is provided for exerting a biasing force to urge the disk into engage¬ ment with the grounding surface. Upon rotation of the motor in one direction, the agitator is rotated in alternate clockwise and counterclockwise directions with the brake assembly grounding the transmission in re¬ sponse to the spring biasing force. Upon rotation of the motor in another direction, the disk and grounding surface are driven apart by the ball ramp against the biasing force of the spring, thereby allowing the transmission to be bypassed with the basket rotating to perform the spin function. Upon interruption of torque output from the motor, the spring biasing force urges the disk as guided by the ball ramp into engagement with the grounding surface to brake basket rotation.

According to another embodiment of the inven¬ tion, the brake assembly comprises a rotatable disk and a grounding surface which is held stationary with respect to the drivetrain base. The disk and grounding surface are axially shiftable relative to each other. A ball ramp is provided for controlling axial and rotational movement of the disk relative to the ground¬ ing surface. Upon rotation of the motor in one direc¬ tion, the agitator is rotated in alternate clockwise and counterclockwise directions with the brake assembly grounding the transmission as a result of gravity biasing the disk into engagement with the grounding surface. Upon counterclockwise rotation of the motor, the disk and grounding surface are driven apart by the ball ramp against the gravity biasing force allowing torque to be provided directly to the basket, bypassing the transmission. Upon cessation of the rotation of the motor in the other direction, the gravity biasing force urges the disk into engagement with the grounding surface to stop rotation of the basket. The gravity biasing force is derived from the weight of the cloth- ing, basket, tub, agitator and transmission assembly and which is the mass upon which the gravity biasing force acts to urge the disk into engagement with the grounding surface.

The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.

BriefDescription OfThe Drawings

FIGURE 1 is a side elevation view partially broken away of a washing machine including the improved brake system of the present invention;

FIGURE 2 is a fragmentary cross-sectional view taken along the line 2-2 in Figure 1;

FIGURE 3 is a top plan view of the brake assembly of the present invention;

FIGURE 4 is a cross-sectional view taken along the line 4-4 in Figure 3; FIGURE 5 is a top plan view of the lower ball race of the ball ramp of the present invention;

FIGURE 6 is a cross-sectional view taken along the line 6-6 in Figure 5; and

FIGURE 7 is a cross-sectional view of an alternative embodiment of the brake assembly of the present invention.

Best Modes For Carrying Out The Invention

Referring now to Figures 1 and 2, a clothes washing machine 10 is generally indicated. The clothes washing machine 10 has a suspended drivetrain base 12 to which a wash tub 14 is mounted. A perforated basket 16 is mounted within the wash tub for retaining clothing during the wash, rinse and spin cycles. An agitator 18 is provided within the basket 16 for agitating clothing in the wash water with an oscillating clockwise and counterclockwise motion. A drivetrain, generally indicated by reference numeral 20, comprises a revers¬ ible motor 22 which drives a driveshaft 24 through a bidirectional clutch output pulley 25, a drive belt 26, and a driven pulley 27 and one way clutch input 28. A brake assembly, generally indicated by reference numeral 30, is provided as part of the drivetrain 20 on the driveshaft 24.

As shown in Figure 2, a conventional trans¬ mission 32 for a washing machine 10 is provided on the driveshaft 24 for providing speed reduction and an oscillating gear drive by means of a gear set 34. The brake assembly 30 includes a housing 38 having a radial flange 40 which is mounted to be stationary on the drivetrain base 12. A disk brake rotor 42 is connected to a driveshaft bearing housing 43 by a splined tube 44. The splined tube is fixed to the driveshaft bearing housing 43. The disk brake rotor is axially shiftable on the splined tube 44. The disk brake rotor 42 is shifted by a ball ramp assembly generally indicated by reference number 45. The disk brake rotor 42 includes splines 46 which are secured to corresponding splines 48 on the splined tube 44. The splines lock the disk brake rotor 42 to the splined tube, holding them together for rotational movement, but allowing limited axial movement therebetween.

A conventional anti-friction bearing 50 is provided between the housing 38 and the driveshaft bearing housing 43 permitting the driveshaft bearing housing 43 to rotate relative to the housing 38. At least one helical compression spring 52 is provided for biasing the disk brake rotor 42 into engagement with radial flange 40. As shown, one spring 52 is disposed about the outside of the axially shifted tube 44.

A lower ball ramp race 54 is secured by the one-way clutch 28 to the upper ball ramp race 56. Ball bearings 58 are provided within the upper and lower ball ramp races 54 and 56 to permit axial and limited rota¬ tional movement between the upper and lower ball ramp races 54 and 56. The disk brake rotor 42 is permitted to move axially a limited extent, approximately 0.060 inches, permitting the disk brake rotor 40 to run free relative to the ground. A plurality of brake pads 60 are provided on either the disk brake rotor 42 or the radial flange 40. In the illustrated embodiment the brake pads are at¬ tached to the disk brake rotor 42.

Referring now to Figure 3, the disk brake rotor 42 is shown in greater detail. The disk brake rotor 42 includes splines 46 which are adapted to be received on splines 48 of the axially shifted tube 44. A plurality of support ribs 62 may be provided to reinforce the disk brake rotor 42. Three brake pads are shown in phantom on the lower side of the disk brake rotor. The upper ball tracks 66 are also shown in phantom as it appears on the lower surface of the disk brake rotor 42.

Referring now to Figure 4, the disk brake rotor 42 is shown in cross-section wherein the splines 46 and upper ball ramp race 56 are illustrated.

Referring now to Figure 5, the lower ball ramp race 54 is shown in top plan view with three ball tracks 64 being provided on the lower ball ramp race 54 at three spaced locations. As shown in Figure 2, the inner diameter of the lower ball ramp race 54 includes a plastic, combination radial and axial sleeve bearing 65. The combination bearing 65 is placed between the lower ball ramp race 54 and a driveshaft bearing housing 43.

As shown in Figure 6, a flange 55 to the one¬ way clutch extends below the lower ball ramp race 54 and is adapted to be secured to the one-way clutch 28. The one-way clutch provides rotational drive input to the ball ramp assembly 45 as will be described more fully below.

In operation, the driveline functions of the clothes washing machine include a wash cycle, rinse cycle, and a spin cycle. In the wash cycle, the clothes washing machine works soap and water through the clothes. Clothes, water and soap are contained in the wash basket and tub. The motor 22 initially rotates in a clockwise direction, assuming plan view orientation, so that the motor shaft drives through a bidirectional clutch output pulley 25. The clutch output pulley 25 drives the driven pulley and one way clutch input 28 through belt drive 26. The driven pulley and one way clutch input 28 are rigidly attached to driveshaft 24. The driveline brake 30 of the present invention is a normally "on" device which connects the transmission housing 32 to the drivetrain base 12 (ground) . When the driven pulley 27 rotates clockwise, it releases the one way clutch 28 and allows the driveshaft 24 to rotate. The transmission 32 is a conventional transmission including a speed reduction gear set 34 and a rack and arm configuration to provide alternative 105 degree rotation in the counterclockwise and clockwise directions. This causes the agitator 18, which is rigidly connected to the output shaft 67, to be alter¬ nately rotated within the shaft housing 68 in clockwise and counterclockwise directions.

The transmission 32 is mounted to the drivetrain base 12 through an antifriction bearing. The transmission 32 is thereby restrained from translational movement relative to the drivetrain base 12. The brake

30 provides the rotational restraint between the trans- ission 32 and the drivetrain base 12 when the brake 30 is on. The brake is normally on during clockwise motor rotation. The basket 16 is preferably rigidly mounted to the transmission 32.

During the spin cycle, wash water is removed from the clothing contained in the basket 16 using centrifugal action. At the beginning of the spin mode, the wash tub 14 is full of water. Generally, a water pump (not shown) is used to pump most of the water out of the tub 14. After most of the water is removed, the motor 22 is reversed and operated in a counterclockwise direction. The motor 22 drives through the bidirec¬ tional clutch output pulley 25. The clutch output pulley 25 drives the driveshaft 24 through the drive belt 26 and input pulley 27 in a counterclockwise direction. The one-way clutch 28 locks and begins rotating the lower ball ramp race 54 causing a relative rotation of the lower ball ramp race 54 relative to the upper ball ramp race 56. This relative rotation causes the disk brake rotor 42 and its associated brake pads 60 to be lifted out of engagement with the radial flange 40. When the disk brake rotor 42 is lifted, the spring 52 is compressed. The disk brake rotor 42 is splined to the driveshaft bearing housing 43, allowing axial movement of the disk brake rotor 42 relative to the transmission 32 but preventing rotational movement between the transmission 32 and the disk brake rotor 42.

The relative rotation and lifting movement continues until the balls 58 reach the end of the ball tracks 64 and 66. At this point, substantially full motor torque is transmitted through the one way clutch

28 to the transmission 32. It should be noted that the basket 16 is rotated along with the transmission 32, agitator 18, wash water, and clothing. The torque applied causes the basket 16 to accelerate to a nearly synchronous speed with the motor rotation. This creates a minimum slip condition for the bi-directional clutch 25.

The spin cycle continues for a predetermined time as controlled by the machine timer. During this time, water is centrifuged from the clothing and the basket 16 to the tub 14 and water pump. This water is then pumped out of the machine.

At the end of the spin cycle, power to the drive motor 22 is cut off and the output torque of the motor 22 decreases to zero. This causes the torque that was supplied to the lower ball ramp race 54 to fall to zero. When this occurs, the force opposing the biasing force of the spring 52 is removed and the spring 52 forces the disk brake rotor 42 back into engagement with the radial flange 40. The brake pads 60 of the disk brake rotor 42 once again engage the radial flange 40. The brake pads 60 apply a brake torque against the rotating washer basket 16, agitator 18, and transmission 32, stopping their rotation.

Referring now to Figure 7, an alternative embodiment of the present invention is shown wherein the brake assembly 70 utilizes the mass of the basket, agitator, transmission, clothes and water contained within the tub to develop braking torque. The brake assembly 70 includes a housing 72 which is mounted stationary relative to the drivetrain base (not shown) and includes housing flange 73. The transmission housing 74 is axially shiftable to a limited extent and provides a mounting surface for the brake pads 76. A ball ramp assembly generally indicated by reference numeral 78 is provided between the outer housing 80 and the transmission housing 74. Driveshaft bearing housing 82 journals the driveshaft 83 and is fixedly connected to the transmission housing 74. Ball bearings 84 contained within ball races 86 provide limited axial and rotational movement between the lower ball ramp race 88 and upper ball ramp race 90. The ball ramp 78 causes the transmission housing 74 to be lifted upon counter¬ clockwise rotation out of engagement with the housing flange 73, separating the housing flange 73 from the brake pads 76. Anti-friction bearing 92 is provided between the housing 72 and the outer housing 80 to permit relative rotation between the outer housing 80 and the housing 72.

In operation, the alternative brake assembly 70 may be mounted within a washing machine similar to that shown in Figure 1 but having a tub mounting that will allow for 0.060 inches of axial movement relative to the drivetrain base. Upon clockwise rotation of the driveshaft 83, the brake pads 76 remain in contact with the housing flange 73 and provide a ground to the transmission (not shown) . Upon initiation of the spin cycle by rotation of the driveshaft in the counterclock¬ wise direction, the ball bearings 84 and the ball races 86 shift the lower and upper ball ramp races 88 and 90, causing brake pads 76 to be lifted from the housing flange 73. It should be noted that the tub, transmis¬ sion, basket and agitator are all lifted with the upper ball ramp 90. This allows the transmission 74, as well as the agitator and basket (not shown) to be rotated in a direct-drive relationship by the outer housing 80.

Upon cessation of the spin cycle, the ball bearings 84 are urged by the gravitational biasing force of the weight of the clothing in the tub and other elevated parts which forces the ball bearings to the lowered position, allowing the upper ball race to shift axially, allowing the brake pads 76 to again engage the housing flange 73 thereby applying a braking torque on the spinning load.

The above embodiments of the present invention are intended by way of illustration and should not be read in a limiting sense. The broad scope of the present invention should be construed by reference to the following claims.

Claims

What Is Claimed Is:

1. In a clothes washing machine having a drivetrain base, a wash tub fixedly mounted on the drivetrain base, a perforated basket disposed within the wash tub, an agitator disposed within the basket, and a drivetrain including an output shaft extending into the wash tub and secured to the agitator in a driving relationship, a shaft housing extending into the wash tub and secured to the basket, a driveshaft journaled within a driveshaft bearing housing, a motor providing a reversible rotary input to the driveshaft, a transmis¬ sion connected between the drivetrain and the output shaft, and a one-way clutch connected to the drivetrain, the drivetrain further comprising: a brake assembly connected to the driveshaft bearing housing, said brake assembly comprising a rotatable disk and a grounding surface which is held stationary relative to said drivetrain base, said disk and grounding surface being axially shiftable relative to each other, said brake assembly including a ball ramp assembly having a lower race and an upper race and adapted to control the axial and rotational movement of the disk relative to the grounding surface, and wherein a biasing force urges the disk into engagement with the grounding surface, whereupon rotation of the motor in a first direction, the agitator is alternately rotated in clockwise and counterclockwise directions with the brake assembly grounding the transmission as a result of the biasing force, and whereupon rotation of the motor in a second direction, the disk and grounding surface are driven apart by the ball ramp assembly against the biasing force allowing the transmission to be bypassed so that the basket is rotated, and wherein interruption of torque output from the motor causes the biasing force to urge the disk into engagement with the grounding surface for braking said basket.

2. The clothes washing machine of claim l wherein said motor is connected to the driveshaft through a bidirectional clutch and drive belt to the one-way clutch.

3. The clothes washing machine of claim 1 wherein said rotatable disk defines an upper race of the ball ramp and a lower race of the ball ramp is secured to the one-way clutch.

4. The clothes washing machine of claim 1 wherein said driveshaft bearing housing is secured to a tubular sleeve which is connected to the rotatable disk for axial shifting of the disk on the tubular sleeve by interfitting splines.

5. The clothes washing machine of claim 1 wherein the rotatable disk has brake pads on one side.

6. The clothes washing machine of claim 1 wherein said ball ramp includes three arcuately spaced ball ramp tracks defined by a lower ball ramp race and an upper ball ramp race and further includes a ball bearing in each of the ball ramp tracks.

7. The clothes washing machine of claim 1 wherein the biasing force is provided by a spring.

8. The clothes washing machine of claim 7 wherein the spring is at least one helical compression spring.

9. The clothes washing machine of claim 7 wherein the compression spring is retained at a first end in a fixed axial location on the driveshaft bearing housing and bears upon the disk on a second end permit- ting axial shifting of the disk.

10. The clothes washing machine of claim 1 wherein the transmission rotates with the basket and the disk when the motor rotates in the second direction.

11. The clothes washing machine of claim 1 wherein the biasing force is gravity.

12. The clothes washing machine of claim 1 wherein said rotatable disk is fixedly connected to the driveshaft bearing housing.