Patent Abstract:
A collapsible control knob assembly includes a knob having a tunnel therein for receiving a shaft. Stops in the tunnel are configured and arranged to cooperatively stop the insertion of the shaft during assembly. The stops are configured and arranged to shear from the tunnel when a pre-established collapsing force is exceeded.

Full Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This Non-Provisional Application claims benefit to U.S. Provisional Application Ser. No. 60/360,781 filed Mar. 1, 2002. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to control knobs that typically are used on control panels in automobiles, and, more particularly, to collapsing control knob assemblies having control knobs. 
     BACKGROUND OF THE INVENTION 
     The automobile industry continually strives to produce safer and more reliable vehicles. Safety features are being incorporated into all subsystems and components of the automobile. At the same time, automakers continually strive to develop more styles, appearances and convenience features to make their products unique in comparison to those of competitors. While improving safety is a constant, primary concern, the competing desires of safety and styling are often in conflict with each other. Thus, automobile designers are asked to design vehicle components that promote safety and convenience and yet must be aesthetically pleasing to the consumer. To please a variety of customers, different design offerings are necessary. 
     Many safety standards in the automobile industry are intended to improve crash-worthiness of a vehicle, and to prevent, or at least minimize, injuries that may occur to occupants in the event of a crash. One such standard requires that all components on the automobile dashboard collapse in the event of an impact collision. After collapse, no sharp edges can be present, and all control knobs, buttons and the like should protrude only minimally from the surface. A current standard limits the allowable protrusion of knobs or controls to nine millimeters or less. The collapsing action of the dashboard and its components is sometimes referred to as “homoligation”. To meet this standard over all, any and all components such as air control heads that contain buttons or knobs, and other dashboard subsystems must individually meet the collapsing requirement. 
     To meet the standards limiting maximum protrusion of dashboard components, some automobile designers have reduced or even eliminated the use of rotary knobs that must collapse in the event of a crash. Depressible switches in the form of pads are used to toggle through, and select from the various functions that are controlled by the switch. A control panel having only depressible pads readily meets the maximum protrusion standards; however, some consumers find the appearance unpleasing, and the use of touchpad controls difficult, particularly by the driver while driving. 
     It is known to provide collapsing or telescoping buttons or knobs on control shafts. In one known construction, a D-shaft is received in a D-shaped opening of a control knob. The D-shaped opening in the knob is sufficiently deep, and the D-shaped portion of the shaft is sufficiently long that, upon a collision or other collapsing impact, the knob is shoved further onto the shaft, to reduce protrusion of the knob. While this design meets the collapsing requirements, it is necessary that the shape of the knob and the shape of the shaft are complementary. Further, the shaped portion of the shaft must be of sufficient length for the knob to slide further on during a crash. Thus, it is necessary to stock different style knobs for each style shaft used on control items, and to provide shafts having long knob receiving end segments sufficient for the knob to be used. A further problem with this design occurs during normal assembly. Without incorporating the collapsing feature, the length of the D-shaped portion of the shaft is only as long as necessary to receive the knob thereon. During assembly, the knob is slid onto the shaft until it will progress no farther. A natural “stop” is provided, making it easy to install all knobs to the proper depth. By allowing extra room for collapse, it becomes necessary to otherwise control the depth to which the knob is installed. 
     What is needed is a collapsing control having a knob adapted for use on shafts of standard types, but with the knob incorporating the collapsing feature required to meet safety standards. 
     SUMMARY OF THE INVENTION 
     The present invention provides a collapsible control knob assembly in which a control knob has stops establishing a fixed position of the knob on the shaft during assembly, with the stops being severable during a crash to collapse the control knob assembly. 
     In one aspect thereof, the present invention provides a collapsible control knob assembly with a shaft having a distal end and an end portion inwardly of the distal end. A knob has a head and a trunk, the trunk extending outwardly from the head and having a tunnel therein defined by a tunnel surface. The tunnel has an opening at an end of the trunk opposite the head. The tunnel is adapted to receive the end portion of the shaft. The tunnel has at least one rib extending radially inwardly from the tunnel surface. The rib has a rib end inwardly in the tunnel from the opening adapted to abut the shaft. The shaft is adapted to shear the at least one rib from the tunnel surface when a force from a collapsing event exceeds a pre-established limit, forcing the shaft and the knob toward each other. 
     In another aspect thereof, the present invention provides a collapsible control knob assembly with a shaft having an end and an end portion, and a knob slidable over the end portion. At least one stop in the knob abuts the shaft end. Shearing means shears the stop upon a compressive force between the shaft and the knob exceeding a selected limit. 
     In a further aspect thereof, the present invention provides an automobile control knob with a head, a trunk connected to the head, a tunnel in the trunk and at least one shearable stop disposed in the tunnel. 
     An advantage of the present invention is providing a collapsible control knob assembly that is easy to assemble. 
     A further advantage of the present invention is providing a collapsible control knob that operates with common shaft designs, and does not require special shaft configurations for proper homoligation. 
     Still another advantage of the present invention is providing a collapsible control knob design that is adaptable for manufacture to withstand different force limits without collapsing. 
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a collapsible control knob assembly according to the present invention; 
     FIG. 2 is an end view of the control knob shown in FIG. 1; 
     FIG. 3 is a cross sectional view of the assembled control knob assembly, taken along line  3 — 3  of FIG. 2; and 
     FIG. 4 is a cross sectional view similar to FIG. 3, but illustrating the control knob assembly in a collapsed condition. 
    
    
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use herein of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items and equivalents thereof. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now more specifically to the drawings, and to FIG. 1, in particular, a collapsible control knob assembly  10  according to the present invention is shown. Control knob assembly  10  includes a shaft  12 , a spring sleeve  14  and a knob  16 . 
     Control knob assembly  10  is connected to a component of a subsystem for which control knob assembly  10  is provided for operational control and input. For example, control knob assembly  10  may be connected to a blower motor control for controlling the blower motor speed, or may be an environmental control system mode selector switch. However, those skilled in the art will understand that control knob assembly  10  can be used as well on other automobile subsystems and/or in applications other than automobiles. 
     Shaft  12  preferably is of plastic, and includes an end portion  20  having a substantially D-shaped cross section including a flattened segment  22  and an arcuate segment  24 . End portion  20  extends inwardly from a distal end  26  of shaft  12  a distance sufficient to receive spring sleeve  14  thereon. Opposite from distal end  26 , flattened segment  22  of end portion  20  terminates at a ledge  28 . Essentially, ledge  28  is formed at the abrupt transition from flattened segment  22  to the rounded configuration of shaft  12  inwardly from end portion  20 . 
     Spring sleeve  14  is a substantially hollow metal body  30  having a narrowed waist or center portion  32  and slightly wider first and second ends  34  and  36 , respectively. Spring sleeve  14  is also D-shaped in cross-section, having a substantially flat portion  38  and an arcuate portion  40 , each extending the length of spring sleeve  14 . One or more relief slots  42  are provided axially in spring sleeve  14 . 
     As seen most clearly in FIG. 3, spring sleeve  14  fits on end portion  20  of shaft  12 . When assembled on shaft  12 , second end  36  of spring sleeve  14  abuts against ledge  28  of shaft  12 , such that spring sleeve  14  is inhibited from sliding further onto shaft  12 , away from distal end  26 . 
     Knob  16  includes a head  50 , a trunk  52  and an outer shell  54  typically cast as a monolithic structure from plastic or the like. Head  50  includes an outer face  56 , with outer shell  54  depending away therefrom at the peripheral edge of outer face  56 . Shell  54  may be provided with knurls, ridges or other outer surface treatment for easy grasping by an individual using control knob assembly  10 . 
     Knob  16  is provided with a hub  58 , substantially annular in shape and disposed on trunk  52 . Hub  58  is received in a device (not shown) for which control knob assembly  10  is provided for operator input. Hub  58  can thereby provide a bearing surface for rotation of knob assembly  10  in the device (not shown). A key  60  provided at the peripheral edge of hub  58  engages a keyway (not shown) in the device (not shown) for securing knob assembly  10  in proper position, and for providing a positive driving engagement between hub  58  and the device (not shown). Interlocking projections  62  are provided between trunk  52  and hub  58 , and provide positive driving connection between trunk  52  and hub  58 , such that rotation of shell  54  results in rotation of hub  58 . Hub  58  is further provided with a jewel light pipe  64  of tinted polycarbonate or the like, which includes a tail  66  for collecting light from a light source such as, for example, an automobile dashboard and transmitting the light to a slot (not shown) in outer face  56 . The visible strip of light in outer face  56  is used as an indicator or index device for referencing a position of knob  16  as adjustments are made during control operation. Key  60  or tail  66  can also function as a knob stop to inhibit rotation to a previously determined range. 
     Trunk  52  includes a D-shaped tunnel  70  therein, extending inwardly from an end  72  of trunk  52  opposite head  50 . Tunnel  70  is D-shaped similarly to shaft  12  and spring sleeve  14 , thereby having a flattened portion  74  and an arcuate portion  76 . Tunnel  70  is sized and shaped to receive end portion  20  of shaft  12  with spring sleeve  14  disposed on shaft  12 . The nature and shape of spring sleeve  14  on shaft  12  provides a relatively strong frictional engagement between the assembled components, as illustrated in FIG. 3, so that the assembly of shaft  12 , spring sleeve  14  and knob  16  does not pull apart easily. 
     As seen most clearly in FIG. 2, tunnel  70  is provided with one or more axial extending ribs  78  therein. Each rib  78  has a rib end  80  (FIG. 3) spaced inwardly in tunnel  70  from end  72 , and forms a stop in tunnel  70 . Thus, with the end  36  of spring  14  in contact with ledge  28  of shaft  12 , rib or ribs  78  indirectly inhibit further insertion of shaft  12 , when first end  34  of spring sleeve  14  abuts ends  80  of ribs  78  as control knob assembly  10  is assembled. Ribs  78  thereby initially provide a positive stop for consistent positioning of knobs  16  on shafts  12  in an assembly line or other assembly process. 
     Ribs  78  extend radially inwardly in tunnel  70 , but rise only slightly above an inner surface  82  of tunnel  70 , normally no more than about the thickness of the metal in spring sleeve  14 . From rib end  80 , rib  78  extends axially along tunnel  70  a significant distance, and may extend the entire remaining distance of tunnel  70 . Rib or ribs  78  are formed monolithically with trunk  52  such that a single structure is made including head  50 , trunk  52  and shell  54 , with ribs  78  in tunnel  70  formed in trunk  52 . 
     When relative compressive force is applied between knob  16  and shaft  12 , spring sleeve  14  shears the one or more ribs  78  away from inner surface  82  of tunnel  70 . As illustrated in FIG. 4, the sheared away material of ribs  78  accumulates ahead of shaft  12  in tunnel  70 . Even when relative compressive force is applied between shaft  12  and knob  16 , spring sleeve  14  remains in position on shaft  12  in that second end  36  thereof abuts against ledge  28  on shaft  12 . 
     To provide ready, quick shearing of ribs  78  away from inner surface  82  of tunnel  70 , ribs  78  are narrow in both the circumferential and radial directions of tunnel  70 . That is, a cross section of each rib  78  is relatively small. However, even without adjusting the dimensions of ribs  78  the relative resistance to collapse of control knob assembly  10  can be altered by providing more or fewer ribs  78 . Thus, if collapse is to occur at minimal compressive force, only one or several ribs  78  may be provided. However, on the other hand, if control knob assembly  10  is to withstand higher levels of force before collapse occurs, more ribs  78  are provided. 
     In the use of control knob assembly  10  according to the present invention, flat and arcuate portions  38  and  40  of spring sleeve  14  are aligned with flattened and arcuate portions  22  and  24  of shaft  12 . Spring sleeve  14  is inserted onto shaft  12  at end portion  20  of shaft  12 , and is slid therealong until second end  36  of spring sleeve  14  abuts against ledge  28  of shaft  12 . Alternatively, the spring sleeve  14  can be first positioned in the knob and then the shaft  12  is slid or presses into the sleeve  14 . The assembled shaft and spring sleeve are then inserted in tunnel  70  of knob  16 , again by aligning the respective flattened and arcuate portions  74  and  76  of knob  16  with the corresponding portions of assembled shaft  12  and spring sleeve  14 . Knob  16  is slid onto the outer surface of spring sleeve  14  until resistance to further insertion is encountered. Thus, ends  80  of ribs  78  provide an abutment against which further insertion is inhibited. By providing a positive stop for assembly, assembly is simplified, and assembly consistency is achieved. 
     If a compressive event occurs, forcing shaft  12  and knob  16  toward each other, rib or ribs  78  are sheared away from inner surface  82  by spring sleeve  14 . The small amount of material of each rib  78  sheared from surface  82  is accumulated ahead of shaft  12  as fragments  84 , even as shaft  12  is forced further into tunnel  70 . A collapsed condition of control knob assembly  10  is illustrated in FIG.  4 . 
     The present invention provides a collapsible knob assembly that functions with common shaft configurations and provides a positive stop for proper assembly of a knob on a shaft. However, upon a compressive event such as during a crash, the positive stops are overcome and collapse of the assembly occurs. 
     Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
     Various features of the invention are set forth in the following claims.

Technology Classification (CPC): 8