Laundry machine with malfunction detection systems

[0001] The present invention relates generally to laundry machines, and more particularly, to malfunction detection systems for laundry machines such as tumbler dryers.

[0002] If certain malfunctions occur in laundry machines, such as tumbler dryers, which are not promptly detected, excessive damage can occur to the machine and potentially dangerous conditions can arise. Tumbler dryers typically have a belt-driven rotary tumbler basket within which laundered items are tumbled during drying. The tumbler basket is perforated and heated air is directed into the basket from an air inlet to the basket as the items are tumbled and discharged from an outlet side of the basket.

[0003] Problems in the operation of tumbler dryers often arise by reason of items left in the pockets of clothes or other garments being laundered. Nails, screws, and other elongated metal items inadvertently left in the pockets of items during laundering can work their way free of the garments during tumbling and migrate to the outer wall of the tumbler basket by reason of centrifugal forces. Such nails and screws quickly find their way through the perforations in the basket with the heads of the fasteners, which are larger than the basket openings, retaining the fasteners in outwardly protruding relation to the basket such that continued rotation of the basket causes the metal fasteners to gauge and damage sheet metal interior panels of the dryer. Fasteners, such as drywall nails, are particularly troublesome since ridges on the shank of the nail tend to prevent dislodgement of the nail from the perforation of the basket even when gauging the interior dryer panels. Such obstructing nails and screws can quickly tear openings into the interior of the dryer which permit ambient air to enter the tumbler from the openings, rather than from the heated air inlet, which in turn can lead to overheating at the inlet of the dryer and the potential for fire.

[0004] Potentially hazardous fire conditions also can rapidly arise by reason of a broken or dislodged drive belt for the rotary basket of tumbler dryers. When rotation of the basket is stopped by reason of a break or uncoupling of the drive belt, the high temperature air introduced from the dryer inlet is concentrated on the item or items closest to the air inlet which are no longer being tumbled. Since the dryer often is unattended, a broken or dislodged drive belt can go undetected for some time resulting in overheating and potential ignition of the garments within the dryer.

[0005] It is an object of the present invention to provide a laundry machine having an improved malfunction detection system.

[0006] Another object is to provide a laundry rotary dryer having an obstruction detection system which will immediately sense and shut down operation of the dryer in the event of an obstruction, such as a nail or screw, protruding through perforations in the tumbler basket beyond a predetermined relatively small distance.

[0007] A further object is to provide a laundry dryer having a broken or dislodged drive belt malfunction detection system which will immediately shut down operation of the dryer in the event of breakage or dislodgement of the drive belt for the rotary tumbler basket.

[0008] Still another object is to provide a laundry machine having obstruction and drive belt malfunction detection systems of the foregoing type which are relatively simple in design and reliable in operation. A related object is to provide such a laundry machine in which the obstruction and drive belt malfunction detection systems utilize a common sensing switch and control circuitry.

[0009] Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawing, in which:

[0020] Referring now more particularly to the drawings, there is shown an illustrative laundry machine 10 having a malfunction detection system in accordance with the invention. The laundry machine 10 in this case includes a pair of vertically stacked tumbler dryers 11 which basically operate in a conventional manner. Since the dryers are identical in construction and operation, only one need be described in detail.

[0021] The illustrated dryer 11 includes a cabinet 12 within which a front opening garment containing tumbler basket 13 is disposed for relative rotational movement. The cabinet 12 includes a front panel 14 adjacent to which a conventional door 15 is mounted, a center panel 16, and a rear panel 18. The tumbler basket 13 has a perforated rear axial end 19 through which heated air is introduced into the tumbler basket 13 in a conventional manner, a rearward unperforated cylindrical portion 20 disposed in sealed relation between the rear panel 18 and the center partition 16, and a forward perforated cylindrical portion 21 disposed between the center partition 16 and the front panel 14. The tumbler basket 13 is supported for rotational movement by a rearwardly extending axle 24 and a pair of rollers 25 mounted in a roller bracket 26 fixed within the cabinet 12 below a front end of the tumbler basket 13.

[0022] For rotatably driving the tumbler basket 13, a drive motor 28 with a drive shaft 29 is provided for driving a belt 30. The belt 30 in this instance is trained about a drive shaft pulley 31, the rearward unperforated portion 20 of the tumbler basket 13, and an idler pulley 32. As is known in the art, through operation of a motor driven fan 34, hot air is drawn from a heater 33, which may be either gas or electric powered, disposed on a rear side of the dryer, through an air inlet 35 communicating with the perforated rear axial end 19 of the basket 13, through the basket and out an air outlet 36 communicating with the forward perforated basket portion 21, through a lint filter 38, and then from the fan to the outside environment.

[0023] During operation of the dryer 11, heated air is directed into and through the tumbler basket 13 as the basket is rotatably driven by the motor 28 and belt 30, causing laundered items within the basket to be tumbled for enhancing air circulation and drying. As indicated above, items inadvertently left in pockets of the garments being laundered can become loose in the tumbler basket. Items 40, such as screws, nails, and other elongated metal items, can quickly migrate in position such that they extend radially outwardly through apertures 41 in the forward perforated section 21 of the basket, being retained in the perforated basket wall by the heads of the fasteners or the like as depicted in FIG. 5. Due to the rapid rotation of the basket 13 necessary for thorough tumbling of the items being dried, such outwardly extending obstructions can quickly gauge and tear the sheet metal interior walls of the dryer cabinet, not only damaging the dryer but also enabling outside air to enter the basket through the torn opening, thereby interrupting the air flow from the heated air inlet 19 and causing a rapid rise in temperature at the inlet 19 that can quickly create a fire hazard.

[0024] In accordance with the invention, an obstruction detection system is provided which will immediately detect obstructions extending from the rotary basket and shut down the dryer before resulting damage can occur. More particularly, an obstruction detection element is provided in closely adjacent relation to an outer perimeter of the perforated cylindrical section of the basket in a manner for engagement by an obstruction, such as a screw or a nail, protruding outwardly of the exterior side of the basket beyond a relatively small distance. In the illustrated embodiment, the obstruction detection element is in the form of a cable 45, such as a stainless steel aircraft type cable, which extends between the guide roller bracket 26 and the center partition 16 of the housing in closely spaced relation to the outer periphery of the perforated basket section 21, such as a radial distance of about 0.25 inches. The cable 45 in this case extends in a direction parallel to the rotary axis of the tumbler basket 13 and is located below the basket at about the seven o'clock position as viewed from the front of the dryer. In other words, the wire is located below the basket on a downstream side of the lowermost point of the basket, as viewed in the clockwise direction of basket rotation. It will be seen that a nail, screw, or like obstructing item 40 extending outwardly through a perforation in the basket beyond the small distance of the cable 45 will engage the cable 45 as the basket rotates. In this instance, the cable 45 is located such that an obstructing item will engage the cable immediately prior to passage upwardly past a left side panel 48 of the dryer cabinet 12, as viewed from the front thereof, which is closely positioned to the side of the tumbler basket 13.

[0025] In carrying out the invention, the cable 45 is operable for activating a dryer shutdown switch in response to being engaged by an obstructing item and immediately shut down operation of the laundry machine. In this instance, the cable 45 is fixed to the roller support bracket 26 at a front end of the dryer, is trained through an opening in the center partition 16, and then through an eye bolt 48 fixed to the rear panel 18 so that a rear end portion of the cable extends parallel to the rear panel 18 to a location at which it is fixed to a switch actuating pivot member 50 mounted for pivotal movement about a pin 51 fixed to the rear dryer panel 18. The pivot member 50 in this case has a general C shape with the pivot point being at one corner, the cable 45 being connected to another corner of the member 50, and a tension spring 52 being connected to a corner of the pivot member 50 diametrically opposed from the cable connection. The tension spring 52 is connected between the pivot member 50 and the cabinet 12 for biasing the pivot member 50 to a passive neutral position, as shown in FIGS. 4 and 6. It will be seen that as a consequence of an obstructing item 40 engaging the cable 45, continued rotation of the tumbler basket 13 in the clockwise direction, as viewed in FIG. 4, will move that portion of the cable 45 adjacent the perforated portion 21 of the basket 13 along with the basket, in turn causing the cable 45 to exert a pulling force on the pivot member 50 for rotating the pivot member about the pivot pin 51 against the biasing force of the tension spring 52, as shown in FIG. 7.

[0026] In further carrying out the invention, a switch 55 is provided which is engageable by pivotal movement of the pivot member 50 in response to an obstructing item engaging and moving the cable 45, which is operable for immediately shutting down operation of the dryer. The switch 55 in this case is a conventional flexible wobble switch which is activated upon being deflected in any direction. It will be understood by one skilled in the art that the switch 55 may be integrated into control circuitry for the dryer such that upon activation, both power to the tumbler drive motor 28 is interrupted and power and/or fuel to the inlet air heating device 33 is terminated. In this instance, as shown in FIG. 9, the switch 55 actuates a normally closed contact 57 to interrupt power to the tumbler basket drive motor 28, fan 34, and heater 33. Since dryer shutdown is nearly immediate, damage to the interior of the dryer is prevented or substantially reduced. Moreover, the danger of a resulting fire from the malfunction is prevented. Following such automatic shutdown, the operator can remove the obstruction 40, inspect the dryer to insure no damage has occurred, and restart the dryer through activation of an appropriate reset switch 53. Hence, the obstruction detecting cable and associated switch activating device effectively serves as an obstruction interlock that will immediately shut down the machine to prevent damage to the dryer and the danger of fire as a result of a potentially harmful obstruction extending out of the basket.

[0027] In keeping with a further feature of the invention, a broken or dislodged drive belt malfunction detection system is provided for also shutting down the dryer in response to breakage or dislodgement of the drive belt 30 that would interrupt rotation of the tumbler basket 13. Again, the detection system operates in immediate response to the drive belt malfunction so as to shut down operation of the dryer prior to potential for overheating or ignition of items within the dryer. To this end, the idler pulley 32 is mounted on a switch actuating pivot member 58 supported for pivotal movement about a central pivot pin 59 fixed to the rear housing panel 18. For biasing the idler roller 32 in a belt tensioning direction, a tension spring 60 is connected between the dryer cabinet 12 and the end of the pivot member 58 opposite the end to which the pulley 32 is mounted. Hence, during normal operation of the dryer, the tension spring 60 biases the pivot member 58 in a clockwise, belt tensioning direction, as viewed in FIG. 6. In the event of breakage or dislodgement of the drive belt from the idler pulley 32 or drive pulley 31, tension of the drive belt 30 will be relieved and the tension spring 60 will pivot the pivot member 58 in a clockwise direction, as viewed in FIGS. 4 and 8, into engagement with the wobble switch 55 located adjacent the end of the idler roller carrying end of the pivot member 58. Activation of the wobble switch 55, whether by the obstruction detection pivot member 50 or the drive belt pivot malfunction pivot member 58, will immediately shut down operation of the dryer. Hence, the switch 55 serves a dual function of detecting both a broken or displaced drive belt, as well as an obstruction protruding from the basket. If either condition occurs, the switch 55 will be activated, shutting down the dryer and the heat source. Since a common sensing switch and shutdown circuitry may be utilized, the detection systems lend themselves to relatively economical design and manufacture. Moreover, it will be appreciated that other features may be included in the detection system, actuated by the common switch, such as illumination of one or more warning lights to bring to the attention of the tumbler dryer operator of the particular malfunction that has occurred.

[0028] From the foregoing, it can be seen that a laundry machine is provided which is adapted to detect multiple malfunctions, utilizing common sensing switches and circuitry, so as to protect the machine from damage and the existence of potentially dangerous conditions resulting from the malfunction. It will be appreciated by one skilled in the art that while the invention has been described in connection with a tumbler dryer, it may be used in connection with other laundry machines, including washing machines. As used herein, the term laundry machine is intended to encompass both washing machines and dryers.