The present invention relates to appliance control knob assembly constructions, and particularly to constructions of control knobs for use in laundry appliances, such as automated laundry washing machines and dryers.
Automated laundry appliances (such as laundry washing machines and dryers) typically include an external generally rectangular cabinet, a control panel for controlling the washer/dryer operation, and a hinged lid or door that may be swung open to provide top or front-load access to a rotatable cylindrical wash basin (in the case of a washer). In use of an automated laundry washing machine, after placing a load of laundry in the wash basin, along with a suitable type and quantity of laundry detergent, a wash process is initiated by an operator through interaction with the control knob. Similarly, with a dryer, a wash load drying process is initiated through interaction with a control knob. The control knob provides a user interface through which a user may make selections of cycles and various wash (or dry) control parameters. Controlled operation sequences may be carried out using an electronic controller that may, e.g., be provided as an integral part of the control panel, or mounted separately and suitably connected therewith. Such a controller may comprise one or more suitably programmed microprocessors or application specific integrated circuits (ASICs), operably connected to suitable circuitry, e.g., for driving the wash basin drive motor, actuating operation components (e.g., valves and a pump) to fill the wash basin and drain it, dispense additives, etc. Such operations will be carried out in accordance with commands of the controller, generated on the basis of program control and possibly also signals received from various sensors monitoring various operation-related parameters.
Many current designs for knobs in washer and dryer consoles comprise a knob shell with a concentric knob shaft on the inside that is supported on its outside diameter by either a cone shape that contacts the knob shaft only over a very small area close to the front face of the knob, or a cylindrical shape that holds the knob shaft over a larger area/length of the knob shaft.
The rearward end of the knob shaft often is supported by an encoder on an electronic circuit board. Alternatively, some knobs are supported only by an encoder. These designs can create problems of displacement of the knob from its intended aligned mounting position and friction between the knob shaft and the supporting geometry. Unwanted lateral movement of the knob may result from the gap necessarily provided between the knob shaft and the shaft support geometry to allow low friction rotation of the knob. This lateral movement may result in undesirable loosening of the knob or misalignment in relation to the encoder that may hinder knob operation. It may also provide an undesirable user feel. As that gap is increased, the lateral movement may allow the outermost diameter of the knob to rub on the surrounding console structure, causing more friction and wear. This issue is even more prevalent on designs where the knob is supported by only the encoder, as there is a much higher moment arm for any lateral forces (including gravity) to affect the position of the knob and allow it to rub on the console. Conversely, as the gap between the knob shaft and its support geometry is narrowed to reduce lateral knob movement, friction between the knob shaft and its support geometry may increase.
Axial movement of, or forces on, the knob also may be a problem. As the knob is pushed inward during use, it may frictionally engage against the knob shaft support geometry leading to undesirable increased rotation resistance. Axially directed forces on and/or movement of the knob can also cause damage to the encoder to which the knob shaft is attached. If the knob is pulled outward from the console during use, there also may be increased friction between the knob shaft and its support geometry. Also, there may be increased friction between the knob and the console. Small dimensional variations on any of the interacting parts, which are to be expected in injection molding processes, can have a great impact on any of these three potential issues.
In view of the foregoing, it is an object of the present invention to provide a control knob assembly and method of assembly that avoids the drawbacks of prior control knob support arrangements. To this end, in an aspect, the present invention provides an appliance control knob assembly including an encoder that has a rotatable shaft. A control knob is connected to the rotatable shaft. A control knob mounting protuberance extends into the control knob and provides a bearing mounting surface. A bearing is mounted on the bearing mounting surface. The control knob has a hub portion extending through the bearing and engaging with the same so as to be rotationally supported therein. The hub portion further engages with the rotatable shaft of the encoder. The encoder is mounted within the assembly such that prior to attachment of the hub portion with the encoder shaft, the encoder is allowed a degree of movement. As a result, upon engagement of the hub portion with the encoder shaft, the encoder shaft comes into alignment with the hub portion.
In a further aspect, the invention provides a control knob assembly method. In that method, a bearing is mounted on a bearing mounting surface of a control knob mounting protuberance. A control knob is mounted on the mounting protuberance such that the protuberance extends into the control knob, and a hub portion of the control knob extends through the bearing. An encoder is movably mounted within a support structure of a control panel assembly. The encoder has a rotatable shaft. The hub portion is engaged with the encoder shaft such that the engagement is able to move the encoder within the support structure to thereby center the shaft with the hub portion in the event of a misalignment of the shaft and hub portion.
These and other objects, aspects and features of the present invention will be readily apparent and fully understood from the following detailed description taken in conjunction with the appended drawings.
Referring to
Referring now to
The illustrated control knob 11 is rotatable in order to permit the user to select operation cycle settings and other control parameters, with reference to selections indicated by words, icons, or other indicia that may be arrayed (in printed form or otherwise) on the fascia about the control knob, and/or used in conjunction with LCD display 13.
The assembly featured in
Also, as shown in
As illustrated in
Prior to the engagement of the knob shaft 21 with the encoder shaft 25, the control knob 11 is mounted within a bearing which is mounted within the mound-like, frusto-conical protrusion 17, that may be formed (e.g., injection molded) as part of the front housing 19. The illustrated embodiment employs a ball bearing 15. In a known manner, the bearing 15 has a generally toroidal shape formed by a pair of concentric rings/races with circumferential troughs that face each other to form therebetween a raceway within which a set of balls is rotatably trapped to rotate and orbit, thereby providing a low friction rotatable mount of the inner ring/race within the outer ring/race of the bearing. The rings/races and balls may be made of various materials including either metal or plastic, and may employ a wet or dry lubricant to further reduce friction and facilitate smooth rotational movement.
Ball bearing 15 may be press-fit into a collar formed by a central circular cavity 16 formed within the protrusion 17. This fixes the outer ring of the bearing with respect to the protrusion, while rotationally mounting the inner ring. The central shaft of the knob 21 may then be press-fit into the inner ring of the bearing. This press-fitting arrangement positively establishes the translational position and orientation of the knob relative to the front housing 19. The relative movement afforded by the mount of the encoder 23 within the rear housing 24 allows the encoder shaft to come into alignment with that position. Thus, the misalignment problems associated with prior designs, where the knob position is at least in part dependent on the (non-movable) encoder position. Moreover, the mount can be made much stronger than prior designs that rely on only the encoder shaft for support.
Crush ribs may be used to effect the press-fit of the outer race ring of the ball bearing firmly within the recess of protrusion 17, and also to effect the press-fit of the knob shaft firmly within the inner race ring of the ball bearing so that the only movement of the knob relative to the front housing is rotation within the ball bearing.
As illustrated in
During the assembly, a sub-assembly of the knob 11, bearing 15, and front housing unit 19 may be engaged as a unit with rear housing 24. In this process, encoder shaft 25 engages with and advances into knob shaft 21, coming into alignment therewith due to the float afforded by the mount of the PCB 27. At the same time, PCB 27 becomes fixed in its aligned position by virtue of hold-down features now described.
As illustrated by
As shown in the illustrated embodiment, there may be three spring arms 33, angularly spaced 120 degrees apart from each other around the axis of rotation of knob 11 (when it is mounted on the front housing 19), in order to evenly clamp the PCB 27 into place. Each of the spring arms 33 is symmetrically formed as two arm segments that emanate from two spaced points on the rear side of the front housing. The two segments extend parallel to each other a first equal distance, turn inwardly toward each other forming a pair of shoulders 35, then taper inwardly further until joining together centrally to form a closed loop and a rounded, rearwardly protruded end 37. It is this end that comes into engagement with PCB 27 (as seen in
In the illustrated embodiments, the control panel assembly and components are implemented in a control panel of an automated laundry washing machine. It will be understood, however, that aspects of the invention may be applied to other automatic washing/drying appliances, e.g., dishwashing machines, and to electronic appliances in general.
The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.