Selector switch having an easily removable knob

A selector switch includes a knob, a bezel and a retaining clip. The retaining clip is mounted on the knob and secures the knob to the bezel. The retaining clip is C-shaped and has a tab centrally disposed on the retaining clip. When the tab is pressed by a tool, the retaining clip contracts and the knob may be detached from the bezel. The tab can be accessed through a slot between the bezel and the knob by a screwdriver. The knob, bezel and retaining clip can be made of plastic.

FIELD OF THE INVENTION 
The present invention relates generally to selector switches. More 
particularly, the present invention relates to a selector switch having a 
knob secured to a bezel by a retaining clip. 
BACKGROUND OF THE INVENTION 
Selector switches are found on panels or operator interfaces of a multitude 
of machinery and equipment. Typically, the selector switches are attached 
to a switch assembly or switch housing which is secured to a panel. The 
selector switches can have push button, toggle, rotary, momentary, or 
other action. 
Generally, a selector switch is comprised of a knob mounted on a threaded 
bezel. The knob is secured onto the bezel by a C-shaped retaining clip. 
The knob typically includes a selection indicator which points to various 
options displayed on the panel. The bezel is generally threadably engaged 
or snapped onto the switch housing disposed in the panel. 
Some selector switches include an associated illumination device which 
provides a representation of the status of the selector switch or of 
operating conditions associated with the panel. Some selector switches 
include internal illumination devices such as lamps, bulbs, LED's or other 
lights which provide illumination for the selector switch. Typically, the 
illumination device sits in front of the switch housing beneath the bezel. 
The illumination device is disposed on a latch and power module fixed 
within the switch housing. For these illuminated selector switches, the 
switches must be disassembled to replace the illumination device from the 
front of the panel. 
In conventional illuminated selector switches, the bezel must be threadably 
disengaged from the switch housing to access the illumination device. 
Alternatively, the illumination device may be accessed from behind the 
panel. Gaining access to the illumination device by these approaches is 
disadvantageous because the bezel must be removed to gain access to the 
device. Removal of the bezel can be a time consuming process. 
Thus, there is a need for an advantageous arrangement for holding a knob of 
a selector switch onto a bezel. The arrangement should allow a selector 
switch to be quickly and easily disassembled from the front of the panel. 
SUMMARY OF THE INVENTION 
The present invention relates to a selector switch. The selector switch 
includes a bezel having an interior cylindrical surface, a knob mounted on 
the bezel, and a retaining clip. The knob has a lower cylindrical portion. 
The lower cylindrical portion fits inside the interior cylindrical surface 
of the bezel when the knob is mounted on the bezel. The retaining clip is 
engaged to the lower cylindrical portion of the knob. The retaining clip 
has a tab and is configured to secure the knob onto the bezel. A slot is 
disposed between the knob and the bezel. The slot is configured to provide 
access to the tab of the retaining clip. 
The present invention further relates to a retaining clip for use in a 
selector switch including a knob and a bezel. The knob has a selection 
indicator and a lower cylindrical portion. The bezel has an interior 
cylindrical surface. The retaining clip includes a C-shaped ring 
configured to mount on the lower cylindrical portion of the knob and to 
secure the knob onto the bezel, and a tab mounted at a middle portion of 
the C-shaped ring. 
The present invention still further relates to a method of removing a knob 
from a bezel in a selector switch. The method includes steps of: inserting 
a tool into a slot, pressing the tool against a tab, and removing the knob 
from the bezel. The slot provides access to the tab mounted on the 
retaining clip. The tab causes the retaining clip to contract to a 
diameter smaller than a diameter of an interior cylindrical surface of the 
bezel when the tool presses against the tab. 
The present invention advantageously holds the knob of the selector switch 
onto the bezel. The present invention facilitates the replacement of lamps 
in illuminated selector switches because the selector switch can be 
dissembled without removing the bezel from the panel. A tab on the 
retaining clip allows the knob to be released from the bezel. According to 
an aspect of the present invention, the bezel has a rim at the top of a 
interior cylindrical surface and the knob has a groove which receives the 
retaining clip. The retaining clip is held within the groove and beneath 
the rim to secure the bezel to the knob.

DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS 
Referring to FIGS. 1 and 2, a selector switch 10 includes a bezel 20, a 
knob 30, and a retaining clip 40. Generally, selector switch 10 is mounted 
on a panel (not shown). Selector switch 10 and can be illuminated or 
non-illuminated. 
Bezel 20 has an interior cylindrical surface 22. Interior cylindrical 
surface 22 is configured to receive a lower cylindrical portion 34 of knob 
30, when knob 30 is mounted on bezel 20. Bezel 20 includes a retaining rim 
41 at the top of surface 22. Bezel 20 is preferably made of plastic. One 
such plastic is a 30% glass-filled polyester or Celenex 3316. Bezel 20 and 
interior surface 22 can be circular or polygonally shaped. 
Knob 30 is mounted on bezel 20 such that lower cylindrical portion 34 of 
knob 30 is disposed within interior cylindrical surface 22 of bezel 20. 
Knob 30 is preferably made of plastic. For example, knob 30 may be made of 
GRILLAMID TR55 nylon. Knob 30 and lower cylindrical portion 34 can be 
circular or polygonally shaped. Knob 30 can also be a toggle lever or 
other user actionable device. 
Knob 30 includes a pointer or selection indicator 32 and a groove 36. 
Indicator 32 can be a colorful piece with any of a variety of markings. 
Indicator 32 may be removed from knob 30 and replaced with another 
indicator of a different color or marking. Groove 36 is disposed in and 
around lower cylindrical portion 34. Groove 36 is configured to receive 
retaining clip 40. 
Knob 30 is secured onto bezel 20 by retaining clip 40. Retaining clip 40 is 
a flexible C-shaped ring and includes a tab 42. Retaining clip 40 is 
mounted in groove 36 and around lower cylindrical portion 34 of knob 30. 
Tab 42 is located at an opposite end from indicator 32 when retaining clip 
40 is mounted on knob 30. Knob 30 and retaining clip 40 are inserted into 
bezel 20 by radially compressing retaining clip 40 to a diameter smaller 
than a diameter of rim 41. Once lower cylindrical portion 34 of knob 30 
(with retaining clip 40 mounted in a groove 36) is placed in bezel 20 
retaining clip 40 expands to a diameter larger than a diameter of rim 41, 
securing knob 30 onto bezel 20. More particularly, retaining clip 40 is 
held between an upper rim 35 and a lower rim 37 of knob 30 and prevents 
knob 30 from being moved past rim 41 of bezel 20. 
Knob 30 and bezel 20 form a slot 38 when knob 30 is secured onto bezel 20. 
Slot 38 may be a clearance or an aperture and is disposed between knob 30 
and bezel 20 and provides access to tab 42 of retaining clip 40. In 
addition , slot 38 may also be an aperture 39 in knob 30, as shown in FIG. 
2. Tab 42 allows knob 30 to be detached from bezel 20. To remove knob 30 
from bezel 20, a tool 50, such as a screwdriver, is inserted into slot 38. 
Tool 50 is then pressed against tab 42. When tab 42 is depressed by tool 
50, retaining clip 40 contracts to a diameter smaller than the diameter of 
rim 41 on interior cylindrical surface 22, and knob 30 along with 
retaining clip 40 may be detached from bezel 20. 
The advantageous orientation of selector switch 10 places slot 38 at an 
opposite end of indicator 32 so an operator can more easily find slot 38 
and hence tab 42. The easy removal of knob 30 allows an operator to 
replace lamps within the housing (not shown) to which bezel 30 is 
attached. Be removing knob 30 from the top of the panel, the operator does 
not have to completely remove bezel 30 or access switch 10 from behind the 
panel. 
Retaining clip 40 is preferably made of a flexible plastic. For example, 
retaining clip 40 may be made of acetal as manufactured by 
HOECHST-CELANESE, CELCON M90-04. One unexpected advantage of the present 
invention is a more uniform retaining clip. With prior C-shaped retaining 
clips, plastic is injected at one end of a C-shaped clip mold. Injecting 
plastic from one end results in an uneven amount of plastic throughout the 
retaining clip, with more plastic at the input end and less at the other. 
The tab on the retaining clip of the present invention provides a natural 
input of plastic for injection molding. Because the tab is located at the 
middle of the C-shaped retaining clip, both ends will receive the same 
amount of plastic. 
If selector switch 10 does not utilize a lamp or other illumination device, 
knob 30 can be permanently attached to bezel 20 by utilizing clip 40 
without tab 42. Economies of scale can be achieved by utilizing 
essentially the same components for illuminated and non-illuminated 
selector switches. Clip to can be configured for permanent attachment by 
simply removing tab 42. 
It is understood that the above description is of a preferred exemplary 
embodiment of the present invention. The apparatus and method of the 
invention are not limited to the specific form shown. For example, 
although plastic materials are suggested and a rotary know is shown, other 
shapes and materials can be utilizes. Various modifications may be made to 
the details of the disclosure without departing from the spirit of the 
invention which is defined in the appended claims.