Panel mount for mounting signalling and control devices on control panels

A panel mount for supporting an electronic device at a hole in a control panel and mountable with access to only the front of the panel. It has a housing that slides into a tubular elastomeric grommet. During installation, an expander segment of the housing slides within a bulging segment of the grommet to expand the grommet inward of the hole and for retaining the components within the hole. A tubular male pre-assembly segment on the exterior surface of the tubular housing permits the housing to be pre-inserted partially into the grommet without expanding any part of the grommet radially outward in preparation for inserting the assembled housing and grommet into the panel hole. A withdrawal lock prevents the housing from sliding axially out of the grommet after installation. The withdrawal lock includes a shoulder formed on the grommet and a shoulder formed on the housing.

BACKGROUND OF THE INVENTION

This invention is an improved panel mount for mounting electrical or other devices on panels such as control panels. Various kinds of electronic equipment commonly have control panels on which are mounted various panel mount devices such as audible or visual signaling devices, switches or meters. Many other kinds of machines and equipment, such as vehicles, machine tools, home appliances and farm equipment, also have control panels. Often, instead of a centralized control panel with an instrument cluster, there are multiple, separate, remotely-located panels some even having only a single device mounted on them. A control panel is often mounted to, or is a wall of, a cabinet or other enclosure which contains electronic or mechanical components in order to protect them from the environment or physical contact or to conceal them. Devices that require interaction with human operators but are also connected to the contained electronic or mechanical components are mounted to the panel. The outer side of the panel is accessible to human operators or users and the inner side of the panel faces the contained and protected electronic or mechanical components.

Panels of this type usually have a hole for mounting a panel mount to the panel. The device to be mounted to the panel is normally contained within a panel mount housing that extends through the hole. The panel mount's housing is accompanied by a fastening means for retaining the housing in the hole. One of the most traditional panel mount housings is a tubular housing having a flange at one end and a cylindrical body attached to the flange and threaded. A fastening means for retaining the housing on the panel is a nut that threadedly engages the housing threads. The tubular housing is inserted through the hole in the panel from either the front or the back of the panel. Then the nut is threaded from the opposite side of the panel onto the tubular housing to clamp the housing to the panel. Although that traditional panel mount is effective, it requires simultaneous access to both the front and the back of the panel and requires several manipulative steps in order to mount it to a panel. Additionally, if a gasket is used for sealing or a lock washer is used to prevent rotation of the nut, the traditional panel mount requires three or four parts instead of two.

In order to provide a panel mount that can be installed more easily, simply and less expensively because it requires access to only the outer side of a panel, the prior art provides panel mount housings with resiliently bendable fingers. The fingers are spaced circularly around the housing and oriented generally parallel to a housing central axis. Pushing the housing and its fingers into the hole in the panel deflects the fingers inward toward the axis during insertion. Upon full insertion, the fingers snap radially outward into place and have shoulders that retain the housing in the panel hole. However, many panel mounts of that type do not provide a seal. They often do not tightly hold the panel mount housing rigidly against the panel but instead allow it to wobble in place, especially if the panel mount has been subjected to vibration. Some manufacturers use a spring to prevent wobble but at extreme cold temperatures the spring contracts or distorts and the installed structure wobbles.

It is therefore an object of the invention to provide a panel mount that can be installed with access to only the outer side of a panel yet is retained against withdrawal from the panel, engages the panel in a manner that provides a seal and is tightly held without any wobble.

A further object of the invention is to simplify and reduce the cost of installing panel mounted devices onto a panel by providing a panel mount that can be pre-assembled and then quickly, easily and completely installed with access to only the outer side of the panel by inserting the panel mount into a panel hole and pushing the panel mount inward with a small force in a single linear pushing motion.

A further object of the invention is to simplify the assembly of panel mounted devices onto a panel and reduce manufacturing costs by providing a panel mount that has only two parts

It is a further object of the invention to provide a panel mount that combines the above capabilities with sealing that prevents the passage of any fluids between the hole and the panel mount.

SUMMARY OF THE INVENTION

The invention is a panel mount for containing and supporting a device at a hole in a panel. One component of the panel mount is a tubular, resiliently compressible, elastomeric grommet. The grommet has a grommet flange segment at its axially outer end and a tubular grommet body extending axially inward from the grommet's flange segment. The grommet body further includes an exterior surface including a cylindrical hole segment extending axially inward from the grommet flange segment and having a diameter that is substantially the same as the hole diameter. No part of the exterior surface of the grommet body extends radially outward from the grommet axis further than half the diameter of the hole. The grommet body also has an interior surface that includes a bulging segment that is positioned radially inward of at least a portion of the grommet's hole segment. A second component of the invention is a tubular housing that includes a housing flange segment. The housing also has a tubular housing body extending axially inward from the housing flange segment. The tubular housing body has an exterior surface that includes an expander segment. The expander segment and the bulging segment are axially positioned to come into contacting registration when the tubular housing is fully inserted into the grommet so that the expander segment expands the grommet at a position axially inward of the hole.

Preferably, the tubular housing body also includes a tubular male pre-assembly segment on the exterior surface of the tubular housing body. The tubular male pre-assembly segment permits the housing body to be pre-inserted partially into the grommet and into the bulging segment of the grommet without expanding any part of the grommet radially outward.

Preferably, the housing body and the grommet have cooperating structures to provide a withdrawal lock. An axially inward facing shoulder is formed into the interior wall of the grommet and an axially outward facing shoulder projects radially outward from the exterior surface of the housing. Upon completion of installation, these surfaces come into contact and prevent the housing from sliding axially out of the grommet.

There are additional and preferred structural features that will be described.

In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

DETAILED DESCRIPTION OF THE INVENTION

The following description of the invention begins with a description of a terminology convention and definitions that were adopted to describe the preferred embodiments of the invention and their operation during installation. The description of terminology and definitions is followed by an overview description of the preferred embodiments of the invention and their installation. The overview description will identify the principal component parts and fundamentals of their functional cooperation in general terms. Its purpose is to provide a general orientation to the components of the invention and their structural features and to additionally describe the sequence of steps to install an embodiment of the invention in a hole of a control panel. The overview description is followed by a description of more specific and detailed structural characteristics of the component parts of the preferred embodiments of the invention and their functional cooperation during the process of mounting the components on a panel.

Terminology and Definitions

An initial inspection of the drawings shows that an embodiment of the invention has two basic component parts each having structural features of various different shapes, sizes and configurations. These various structural features have diameters, lengths and positions that allow them to cooperate in a manner that accomplishes the improvements of the invention. A terminology convention has been adopted to facilitate describing them and their respective diameters, lengths and positions. The purpose of the terminology is to assist visualization and provide unique, distinguishable names for the structural features.FIG. 8is provided to facilitate reference to the names adopted for the structural features of the invention.

Looking at the drawings, it can be seen that the two basic component parts of the invention are a tubular housing10and a tubular grommet12. The housing10and the grommet12have a central axis14. As shown inFIGS. 5-7, the housing10becomes inserted in the grommet12and together they become inserted in a hole16in a panel, such as a control panel18shown in phantom. When installed, there is an outer side of the panel which faces toward, and is visible to, a user or operator. There is also an opposite inner side of the panel which, when embodiments of the invention are installed and operable, is usually not visible to the user. The inner and outer sides and directions are labelled onFIG. 7but are applicable to the other figures.

In order to provide a meaningful terminology convention, directions and positions are described with reference to the directions and positions that exist when the component parts are installed even though, when the components are not installed, they have no relevant position or orientation. This terminology is believed to allow for descriptions that are easier to visualize because the descriptions are related to directions and positions when embodiments of the invention are mounted in their intended position on a panel.

Directions along the central axis are described from the perspective of a human user. Because control panels usually are a wall of a compartment or enclosure and the human user is outside the compartment or enclosure, the usual position of the human user is viewed as outside and the inside of the compartment or enclosure is viewed as inside. Directions and positions toward or nearer the outside are described by the terms “axially outer” and “axially outward”. Directions and positions toward the inside are described by the terms “axially inner” and “axially inward”. The adjective “axially” refers to directions and positions relative to the direction of the central axis14.

Other position or direction characteristics of structural features of the component parts are described in terms of “radially inward” and “radially outward”. The adjective “radially” refers to directions and positions relative to the direction of radii that extend perpendicularly from the central axis14. Since the component parts are tubular, they are also described as having an interior surface which is the tube surface that is radially on the inside of the tube and an exterior surface which is the surface that is radially on the outside of the tube.

In addition to the adopted convention for describing positions and directions, an attempt has been made to provide unique names for the structural features of the invention. Many of the names include a word that refers to their function and, when possible, to a word that is commonly used in the art to name or describe similar structures.

Finally, the term “substantially” is used with respect to dimensional characteristics of some of the structural features of the invention's components. As well known to those skilled in the engineering arts, dimensions that most desirably have a particular value can often differ from that particular value by a small amount and yet the variation causes no resulting difference in the operation or effectiveness of an embodiment of an invention. Small dimensional differences from an ideal value often allow operation that is identical to operation when there is no difference. The term “substantially” is used to include differences that are sufficiently small that they do not affect the operation or function of an embodiment. For example, the description of the invention describes inside diameters (ID) that are substantially equal to outside diameters (OD) so that one component can be slid inside another without any meaningful frictional resistance to that insertion and without having to shrink one or expand the other component and yet they are essentially in contact. But if they are not exactly equal so that there is a gap between them, they are still substantially equal if the gap is so small that it does not change the functional or operational characteristics of the invention

Overview Of The Preferred Embodiment Of The Invention

Referring toFIGS. 1 and 2, one principal component of the preferred embodiment of the invention is a housing10which is tubular and has a circular front flange segment20surrounding an outer end22. The housing flange segment20is the part of the housing that seats near the human-visible outer side of the control panel so the flange segment's outer end22is visible to an operator. The housing10is preferably a substantially rigid plastic body.

Referring toFIGS. 3 and 4, the second principal component of the preferred embodiment of the invention is a grommet12which is tubular and has a grommet flange segment24at its outer end27. Importantly, the grommet12is constructed of a resiliently compressible, elastomeric material.

FIGS. 5-7illustrate the sequence of steps for installing the housing10and the grommet12into a hole16in a panel18. The housing10and the grommet12are first preassembled in preparation for mounting them in the hole16of the panel18. To preassemble them, the housing10is inserted partially into the grommet12in a telescoping relationship as shown inFIG. 5. The interfacing segments of the interior surface28of the grommet12(seeFIG. 8) and of the exterior surface30of the housing10have substantially the same diameter. Therefore the grommet12slides easily, in an axial direction, onto the housing10with little or no resistive friction although having little or no space at the interface between them. Therefore in the absence of any substantial forces applied axially to the telescopically assembled housing10and grommet12, they will not fall apart when handled prior to insertion into the hole16or when being positioned at the hole16in preparation for insertion into the hole16.

Following initial assembly of the housing10into the grommet12, the inner end26of the grommet12is placed at the hole16in the position illustrated inFIG. 5. The grommet12and the housing10are then, together as a unit, slid into the hole16until the grommet flange segment24seats against the outer side of the panel18at the position shown inFIG. 6. In order to allow the partially telescoped unit to slide easily into the hole16with little or no friction, the exterior surface25of the grommet and the hole have substantially the same diameter.

The grommet's flange segment24prevents any further insertion of the grommet12into the hole16. The housing10is then slid further in the axially inward direction into the grommet12until the housing's flange segment20seats against the grommet's flange segment24at the position shown inFIG. 7. That final stage of insertion causes two things to happen.

Referring toFIG. 8, the grommet12has a bulging segment32on its interior surface28and the housing10has an expander segment34on its exterior surface30. The first thing to happen is that the grommet's smaller inside diameter bulging segment32slides up onto and over the housing's larger outside diameter expander segment34and is therefore expanded radially outward. Consequently the grommet12is expanded radially outward behind (axially inward of) the control panel18to a diameter that is larger than the diameter of the hole16. That enlargement retains the grommet12against sliding back out of the hole16.

The second thing that happens during the final stage of insertion is the result of cooperating structures at the inner end of the grommet12and on the exterior surface30of the housing10. Those cooperating structures lock the housing10against coming out of the grommet12. To provide the lock, the housing10is provided with a retainer segment36preferably in the form of an annular locking flange. The length of the grommet12is sized so that, at the fully inserted position ofFIG. 7, the grommet's inner end26functions as a shoulder that seats against a shoulder38of the annular locking flange that forms the retainer segment36on the housing10. Therefore the inner end26of the grommet12prevents the housing10from ever sliding out of the grommet12. However, as an important alternative that is illustrated inFIG. 11, instead of having the end of the grommet seat against the shoulder38of the retainer segment36, the grommet can be made longer but provided with an inner, circular groove40formed into its inner cylindrical wall at the fully inserted location of the retainer segment36on the housing10. The retainer segment36would enter into the circular groove40and similarly lock the housing in place in the same manner.

More Detailed Description

This description refers to all the figures but especiallyFIG. 8unless other figures are referenced.

Looking closer at the grommet12, its flange segment24, which is positioned at its axially outer end27, has a radially outer periphery that has a diameter greater than the hole16diameter. The remainder of the grommet12is a tubular grommet body44with an exterior surface25and extending axially inward from the grommet's flange segment24.

The grommet body44includes a cylindrical hole segment42extending axially inward from the grommet flange segment24. That hole segment42has a diameter that is substantially the same as the hole16diameter. Additionally, no part of the exterior surface25of the grommet body44extends radially outward from the grommet axis14any further than half the diameter of the hole16. This relationship assures that, with the grommet12in a relaxed state prior to its expansion, the grommet12will slide easily into the hole16with little or no resistance to its insertion. The grommet's interior surface28includes the bulging segment32which is located radially inward of at least a portion of the hole segment42.

The housing flange segment20of the tubular housing10has a radially outer periphery at its axially outer end22that housing flange segment20has a peripheral diameter greater than the hole16diameter. The housing10also has a tubular housing body46that extends axially inward from the housing flange segment20. The exterior surface30of the tubular housing body46includes the expander segment34. The expander segment34has a diameter greater than the diameter of the bulging segment32on the interior surface28of the grommet12. The expander segment34and the bulging segment32are axially positioned to come into mutually contacting registration when the tubular housing10is fully inserted into grommet12. Consequently, as the expander segment34slides into the bulging segment32, the expander segment34expands the bulging segment32radially outward at locations along the grommet12that are axially inward of the hole. Upon full insertion of the housing10into the grommet12, the bulging segment32has been expanded as shown inFIG. 7.

Both the housing10and the grommet12are provided with structural features for the purpose of firmly retaining the grommet12on the housing10while they are pre-assembled but not yet installed and for the purpose of allowing the assembled components to be inserted into the hole16to the position illustrated inFIG. 6without any substantial resistance to its insertion. For those purposes a tubular male pre-assembly segment48is formed on the exterior surface30of the tubular housing10. The male pre-assembly segment48extends axially outward from the inner end50of the housing10. The male pre-assembly segment48has a diameter substantially equal to the diameter of the bulging segment32(on the interior surface28of the grommet12) when the grommet is in a relaxed, non-expanded state. As a result, the male pre-assembly segment48can be pre-inserted partially into the grommet12and into the bulging segment32of the grommet12without expanding any part of the grommet radially outward. Without any radially outward expansion when pre-assembled, the pre-assembly can be inserted into the hole without any substantial resistance and slid in until the grommet's flange segment24seats against the front surface of the panel16at the positon shown inFIG. 6.

The housing10and the grommet12are also provided with structural features that provide a withdrawal lock to prevent the housing10from sliding axially outward with respect to the grommet12. An axially inward facing shoulder52is formed into the interior surface28of the grommet12. On the preferred embodiment, the inward facing shoulder52is the inner end26of the grommet12. The inward facing shoulder52is axially spaced from the inward facing shoulder of the grommet's flange segment24by a distance X1(seeFIG. 10).

An axially outward facing shoulder38is formed to extend radially outward from the exterior surface30of the housing10. This axially outward facing shoulder38is formed on a retainer segment36of the housing. The retainer segment36is preferably an annular flange surrounding and extending radially outward from the housing10, although it can alternatively be a series of spaced apart segments of an annular flange. The axially outward facing shoulder38is axially spaced from the inward facing shoulder of the housing's flange segment20by a distance (X2) (seeFIG. 9). That distance (X2) is substantially equal to the sum of X1and the axial thickness (X3) of the housing's flange segment20(seeFIG. 10).

Consequently, as illustrated inFIG. 7, when the assembly is pushed entirely into the hole16, the axially inward facing shoulder52of the grommet12seats against the axially outward facing shoulder38on the retainer segment36of the housing10. These interfacing shoulders prevent axially outward movement of the housing10with respect to the grommet12.

Desirably, the retainer segment36has an inclined or frusto-conical axially inward surface58to minimize insertion resistance by smoothly guiding the grommet's bulging segment32over the retainer segment36. A frusto-conical inclined segment54on the exterior surface30of the housing10is positioned between the housing's expander segment34and its retainer segment36for guiding the bulging segment32up and onto the expander segment34.

An alternative but functionally equivalent embodiment of a withdrawal lock is illustrated inFIG. 11. The grommet12A is longer than the grommet12because the grommet has been extended further inward. An annular groove40is formed into the interior surface of the grommet12A. The annular groove40has an axially inward facing shoulder52A. Consequently, when the alternative embodiment ofFIG. 11is fully installed, the outward facing shoulder38of the housing10seats against the inward facing shoulder52A to prevent withdrawal of the housing10.

Returning to the preferred embodiment, preferably the interior surface28of the grommet12has a female pre-assembly segment56extending axially inward from the axially outer end27of the grommet12. The female pre-assembly segment56has a diameter that is substantially equal to the diameter of the bulging segment32of the interior surface28of the grommet12. The retainer segment36of the housing10may have a diameter at its periphery that is substantially equal to the diameter of the expander segment34of the housing10.

One result of the dimensional relationships of these diameters is that the housing10can be pre-assembled farther into the grommet12without any substantial resistance to its insertion. More specifically, the housing10can be inserted far enough that the retainer segment36is within the grommet12and also far enough that the grommet's interior surface28at the grommet's outer end27is co-linear with the housing's exterior surface30at the housing's expander segment34. As a result, without any expansion of the grommet12, the grommet's interior surface28at the grommet's outer end27is already at the diameter of the expander segment34making it easier to initiate the entry of the expander segment34into the bulging segment32. These relationships make it easier, during the final installation stage, to push the housing10further into the grommet12to their final position shown inFIG. 7.

Another result of the diameter relationships is to avoid a problem that could arise because the radial gap is very thin between the exterior surface of the housing's expander segment34and the radially inward facing boundary of the hole. As previously explained, the purpose of the expander segment34of the housing10is to expand the grommet12radially outward by a substantial distance immediately axially inward of the panel18. However, the radial gap between the hole and the housing10is so thin that any substantial radially outward expansion of the grommet12by the expander segment34at that radial gap during insertion would cause a substantial increase in the frictional resistance to insertion. The reason is that, at that radial gap, the grommet material is so thin that a small amount of radially outward compression by the expander segment34would squeeze the grommet material as far as it could be compressed and result in increased resistance to insertion. Because of the female pre-assembly segment56, the expander segment34of the housing10does not expand the grommet12radially outward at the hole. To accomplish that, the female pre-assembly segment56has an axial length (X5) at least equal to the sum of the axial length (X3) of the grommet's flange segment24(seeFIG. 10) and the thickness (X4) of the panel18(seeFIG. 7). The dimensional relationships that have been described provide the advantageous result that, with the components fully assembled, the segment of the grommet12between the hole16and the housing10is not in a compressed state.

It is also desirable to provide a frusto-conical transition segment60that is positioned on the interior surface28of the grommet12extending between and blending together the female pre-assembly segment54and the bulging segment32. This transition segment60helps guide the retainer segment36and the expander segment34of the housing's exterior surface30over and onto the bulging segment32.

REFERENCE NUMBER LISTING

16hole in control panel

20flange segment of housing

22Outer face of housing flange segment

24flange segment of grommet

25exterior surface of grommet

26inner end of grommet

27outer end of grommet

28interior surface of grommet

30exterior surface of housing

32bulging segment of grommet

34expander segment of housing

36retainer segment of housing

38shoulder of retainer segment

40inner groove in the inner surface the grommet

42hole segment of the grommet

46tubular housing body

50inner end of housing

52axially inward facing shoulder of preferred grommet

52A axially inward facing shoulder of alternative grommet

54inclined segment of housing

56female pre-assembly segment of the grommet

58inclined surface of retainer segment36

60frusto-conical transition segment of grommet