Belt Position Indicator Switch With Feeler Arm

Abstract

A position indicator for conveyor belts, drive belts, or the like adapted to be engaged by the edge of a misaligned or off-center running belt, sufficient displacement of the indicator causing actuation of an electric switch for stopping the belt drive motor, indicating an alarm, or the like. The indicator includes an electric switch housing of nonmagnetic material having a magnetic actuating arm, and a magnet mounted upon a lever exteriorly mounted upon the switch housing engageable by the edge of the belt produces actuation of the switch arm upon the lever being sufficiently displaced in close proximity to the housing.

Description

BACKGROUND OF THE INVENTION

The invention pertains to the field of belt position indicators wherein misalignment of a running conveyor or drive belt is mechanically sensed to produce an electric control or alarm signal.

Material handling systems often employ conveyor belts, particularly for transporting bulk material, packages, boxes, etc. Such belts normally travel in a linear path passing over a drive roller and an idler roller at opposite ends of the conveyor, and the belt is supported intermediate the rollers by a platform, bogey wheels, idler support rollers, or other known apparatus. Often, in very long convyor systems, or systems of a complex nature, the conveyor belts are remotely located from an operator, and not readily observable. It is not uncommon for a conveyor belt to become misaligned upon its drive or idler roller due to a variety of reasons, such as a fracture occurring in the belt, a buildup of foreign material on the drive or idler roller, or a jam up of the material being conveyed. In such instance the conveyor belt may be sufficiently displaced upon its rollers to cause wear and tearing of the belt edges as it engages conveyor support structure, or the belt may completely run off of its rollers stopping belt movement, and creating severe problems if the disabled conveyor belt is receiving goods from other material handling apparatus which continues to operate.

Various types of alarm and indicating devices are used with material handling systems to indicate malfunctioning, and to automatically stop the motors driving the devices in the event of problems. Devices are known for sensing malfunctioning of belt conveyors, such as U.S. Pat. No. 3,345,415, and devices are known for sensing the location of drive belts, as shown in U.S. Pat. No. 1,713,171. However, known apparatus is not of a dependable nature if inactive for long periods of time in adverse environments and is not capable of efficiently and dependably operating when required during those infrequent times in which belt malfunctioning occurs.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a belt position indicator capable of indicating misalignment or runout of a conveyor or drive belt wherein the indicator is dependable in operation between long periods of inactivity, nonaffected by adverse environmental conditions, economical in construction and manufacture, and relatively concise in configuration for ease of mounting.

In the practice of the invention a housing of nonmagnetic material is provided with a cover plate such as to define an enclosed chamber which may be dust proof or liquid tight, if desired. Within the housing chamber an electric switch is located having a magnetic arm displaceable between switch operating positions. The arm is located adjacent a wall of the housing. A lever is exteriorly mounted upon the housing and includes means for normally maintaining the lever spaced from the housing wall adjacent the switch arm. The lever further includes a magnet which is located adjacent said housing wall upon the lever being displaced by a misalignment belt, and the lever further includes a free end in alignment with the belt so as to be engaged by an edge thereby upon the belt being displaced from its normal running position. If the belt should become displaced into engagement with the lever, the displacement of the lever locates the lever magnet adjacent the housing, and attracts the switch arm to actuate the switch to stop the belt drive motor, sound an alarm, or the like.

Preferably, the lever is mounted to the switch housing by a leaf spring, and the portion of the lever engageable by the belt is also of a steel construction. However, the magnet mounted upon the lever is located within a nonmagnetic portion of the lever.

The switch housing is provided with a mounting flange wherein the housing may be set into an opening in the edge of a conveyor support rail, or may be otherwise attached adjacent the belt to be sensed by conventional mounting means.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned objects and advantages of the invention will be apparent from the following description and accompanying drawings wherein:

FIG. 1 is a front elevational view of a belt position idicator in accord with the invention,

FIG. 2 is a side elevational view of the device of the invention, a portion of the switch housing being broken away to illustrate the switch structure, and the switch actuating position of the lever being shown in dotted lines, and

FIG. 3 is a rear elevational view of the belt position indicator with the rear cover plate removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The belt position indicator in accord with the invention includes a support member 10 supporting the indicator adjacent the belt with which it is to be associated. The support member preferably takes the form of a housing which may be of a fabricated or cast construction. It is necessary that the wall of the housing disposed adjacent the belt engaging lever be of a nonmagnetic character, and the entire housing may be formed of a nonmagnetic material, either metal or of a synthetic nature, if desired. In the preferred embodiment, the housing 10 is formed of cast aluminum.

The housing 10 is of a generally rectangular configuration, FIGS. 1 and 2, and is hollow and includes a chamber 12 having a rear opening which is normally covered by a cover plate 14 affixed to the housing by screws 16. Removal of the cover plate 14 provides access to the housing chamber 12.

The housing wall 18 is angularly disposed as at 20 to conform to the orientation of the portion of the lever having the magnet located therein, as will be later described.

Mounting of the housing 10 is accomplished by means of a mounting flange 22 peripherally extending from the housing having mounting holes 24 defined therein. In this manner, the housing 10 may be located within a rectangular opening in conveyor structure or other mounting structure disposed adjacent the belt to be sensed. An electric switch is located within the housing chamber 12 threaded openings 26 are defined in the housing for receiving conventional electrical conduit or conductor means which, if desired, may be of the waterproof type.

An electric switch 28 is mounted within the housing chamber 12 upon an insulated mounting plate 30 which is positioned within the housing upon mounting screws 32, FIG. 3 and bushings 34, FIG. 2. Electric switch 28 includes an actuating arm 36 positionable between the full and dotted lines indicated in FIG. 2. The normal position of the switch arm 36 is indicated in full lines in FIG. 2, wherein the switch arm is spring biased to rest against the nonmagnetic stop 38 mounted upon the plate 30. An electric terminal block 40 is mounted upon the plate 30 and includes three screw terminals 42 which are connected to the switch 28 by conductors 44 extending through the mounting plate. The control apparatus, not shown, connected to the switch 28 is connected to the terminals 42 by wires passing through openings 26, and the three terminals permit the option of connecting the apparatus to be controlled by a normally open, or a normally closed switch condition. By way of example, the switch 28 may be of the Micro type BZ-2RW8433, and the switch arm 36 is formed of steel as to be of a magnetic character.

The housing 10 includes a lever mounting boss 46 defined thereon which supports the lever engageable by the belt, generally indicated at 48. The lever 48 includes, at its inner end, a leaf spring 50 of spring steel affixed to the boss 46 by a pair of mounting screws 52, and attached to the lever intermediate portion 54 by screws 56. The normal configuration of the leaf spring 50 is planar and normally maintains the lever 48 in the full line position of FIG. 2.

The intermediate lever portion 54 is preferably formed of cast aluminum, and includes a magnet 58 embedded therein located in alignment with the switch arm 36. The outer free end of the lever 48 is provided with a steel belt engageable portion 60 which is in alignment with the belt 62 to be sensed, so as to be engaged by the belt edge if the belt is displaced sufficiently to the right, FIG. 2. The lever portion 60 is mounted to the intermediate portion 54 by screws 64.

In operation, the housing 10 is mounted adjacent the belt 62 to be sensed in a manner which will be apparent from FIG. 2. Electrical conductors, not shown, are connected to the terminals 42 which are in turn connected to control apparatus for the belt drive motor, or connected to an alarm device, not shown.

In normal operation, the belt 62 will be spaced from the lever portion 60, and the lever will be in the full line position of FIG. 2. In this position the magnet 58 is spaced sufficiently from the switch arm 36 as to have no influence thereon, and as the switch arm 36 is biased by spring means within the switch 28 to normally rest against the arm stop 38, the arm will be located its maximum spacing from the housing wall 20.

In the event the belt 62 becomes displaced to the right so as to engage the lever portion 60, the lever 48 will be rotated in a counterclockwise direction due to flexing occurring in the leaf spring 50. Thus, the lever will be displaced to the dotted line position of FIG. 2 which locates the magnet 58 adjacent the wall 20 and the magnet will then attract the switch arm 36 to the arm position shown in dotted lines in FIG. 2 adjacent the housing wall. This attraction of the switch arm will actuate the switch 28 and produce the desired electrical actuation to stop the belt drive motor, actuate an alarm, or the like.

Upon the belt 62 being restored to its normal condition the lever 48 will assume the full line position of FIG. 2 under the influence of the leaf spring 50, and the switch arm 36 will return to its engagement with the stop 38 since the magnet 58 has been sufficiently displaced from the switch arm to no longer attract the same.

Of course, a conveyor or drive belt may be displaced either to the right or left with respect to its direction of movement, and a belt position indicator in accord with the invention will normally be located upon each side of the belt.

As the support housing 10 may be readily sealed with respect to the surrounding atmosphere, and as no seals, mechanical links, or moving parts are required to interconnect the lever 48 to the switch arm 36, the belt indicator of the invention is capable of providing dependable operation over long periods of time under adverse climatic conditions. The use of the leaf spring 50 eliminates the need for pivots or bearings exteriorly of the housing which might corrode and "freeze" and it will be appreciated that the construction of the indicator is such as to provide dependable operation requiring no maintenance or attention.

It is appreciated that the various modifications to the inventive concept may be apparent to those skilled in the art without departing from the spirit and scope of the invention.

Claims

I claim:

1. A position indicator for moving belt comprising, in combination, a housing defining a chamber, said housing having a nonmagnetic wall, an electric switch mounted within said housing, a magnetically responsive switch operating arm mounted on said switch movable between switch operating positions, a cantilever supported lever externally mounted on said housing movable toward said housing and said switch arm upon being engaged by the edge of a moving belt, said lever including a resilient support portion and a nonmagnetic portion, a magnet mounted on said lever nonmagnetic portion for attracting said switch arm to operate said switch upon said lever being disposed adjacent said housing and switch arm, said lever resilient support portion normally positioning said lever nonmagnetic portion and magnet spaced from said switch arm to prevent attraction of said switch arm by said magnet, said housing nonmagnetic wall being disposed between said lever and said switch operating arm.

2. In a position indicator for a moving belt as in claim 1 wherein said lever resilient support portion comprises a leaf spring attaching said lever upon said housing.

3. In a position indicator for a moving belt as in claim 1 wherein said entire housing is formed of a nonmagnetic material.

4. In a position indicator for a moving belt as in claim 3 wherein said housing comprises an aluminum casting.

5. In a position indicator for a moving belt as in claim 1 wherein said lever mounted upon said housing includes an inner mounted end, an intermediate portion and an outer free end, said inner end constituting a leaf spring defining said resilient support portion, said intermediate portion defining said nonmagnetic portion, and said outer free end comprising a belt engageable member.