GB2107268A

GB2107268A - >A safety system for a conveyor

Info

Publication number: GB2107268A
Application number: GB08222533A
Authority: GB
Inventors: Michael Gary Sargeant
Original assignee: JH Fenner and Co Ltd
Current assignee: JH Fenner and Co Ltd
Priority date: 1981-08-08
Filing date: 1982-08-04
Publication date: 1983-04-27
Also published as: GB2107268B

Abstract

A safety system for detecting faulty bearings of rollers supporting an endless belt conveyor includes an infra-red radiation sensor which is positioned to sense changes in temperature of the conveyor belt. In one method the conveyor is stopped for a time to allow localised heating of the conveyor belt in the region of any faulty bearing. The conveyor is then restarted and moved at a known speed and the areas of localised heating sensed by the infra-red sensor. The elapsed time between restarting the conveyor and detecting the localised heating is measured and the position of the faulty bearing identified.

Description

SPECIFICATION A safety system for a conveyor The present invention relates to a safety system for conveyors and has particular application to belt conveyors employing idler rollers.

In certain applications of roller conveyors, e.g.

in underground installations in coal mines, localised overheating of the rollers as a result of bearing seizure is of particular concern since this may be a serious fire risk. It will be appreciated that the detection of bearing seizure and overheating can prove difficult and time consuming where extensive conveyor runs are employed. Manual checking of each bearing on a regular basis would clearly be expensive in man hours, whilst the provision of a temperature probe for each bearing and associated monitoring circuitry would be extremely expensive in terms of both capital and installation cost as well as requiring unacceptable quantities of wire.

It is an object of the present invention to provide a safety system for a conveyor by means of which roller overheating, for example as a result of bearing seizure, can be detected without the need for individual monitoring of each roller.

According to the present invention there is provided a safety system for a conveyor in which an infra-red radiation sensor is used to sense changes in infra-red radiation from the conveyor surface.

The invention provides a safety system for detecting faulty bearings or rollers supporting an endless belt conveyor, the system comprising an infra-red radiation sensor which is positioned, in use, adjacent the surface of the conveyor whereby changes in infra-red radiation of said surface may be sensed.

The sensor responds to changes in belt temperature which occur for example as a result of the belt passing over a seized roller which necessarily increases in temperature due to frictional contact with the belt. The sensitivity of infra-red sensors is such that small changes in temperature can be detected and, by using a comparison technique, rises in belt temperature with respect to ambient temperature may be detected.

According to another aspect of the invention, there is provided a method of detecting faulty bearings of rollers supporting an endless belt conveyor comprising locating an infra-red radiation sensor adjacent the surface of the conveyor in a position to sense the temperature of the conveyor surface, stopping the conveyor for a time to allow localised heating of the belt in the region of any roller having a faulty bearing, restarting the conveyor and moving it at a known.

speed, sensing changes in temperature of the belt using the sensor and thereby identifying any localised heating of the belt surface, and measuring the elapsed time between restarting the conveyor and detecting the localized heating of the belt surface.

Seizure of a bearing will cause the associated roller to run "hot", generating a hot spot on the belt. The location of the "hot" roller may be calculated by measuring the belt velocity and elapsed time for the "hot spot" to pass the sensor.

One embodiment of the present invention will now be described hereinafter by way of example only.

A roller conveyor comprises an endless belt entrained around spaced apart end rollers and a plurality of idler rollers for supporting a load carrying surface of the belt. The end rollers and idler rollers are supported in a frame by way of bearings. In order to detect hot running of the bearings, and hence possible bearing seizure, an infra-red sensor is located at a convenient point along the run of the belt conveyor. The sensor responds to a rate of change in infra-red radiation from the belt surface and when coupled with the necessary amplifiers and filter networks generates a voltage which can be used to create an audible or visual alarm signal.

The safety system relies on heat generated at the roller as a consequence of bearing seizure, being transmitted to the belt of the conveyor, the transducer sensing an increase in the temperature of the belt.

A shutter mechanism is provided as a reference whereby the sensor is mechanically switched between the shutter face and the belt so as to give an output signal corresponding to the temperature of the belt in relation to the ambient temperature of the shutter face. For example the shutter mechanism may comprise a disc driven by a small d.c. motor rotating at constant speed. The disc is placed adjacent the sensor and between the sensor and target. The disc has a hole in it so that the sensor is periodically exposed to the target during the period in which the hole is directly between the sensor and object. Thus the sensor responds with an output related to the difference in temperature between the shutter face and the target object in question.

The location of the deflective roller/bearing may be determined by stopping the conveyor for a predetermined period allowing localised heating of the belt in the region of the defective roller. The conveyor is then re-started and the time taken for the hot spot on the belt to reach the sensor is measured. The position of the defective roller and/or bearing may then be calcuiated from elapsed time and the conveyor velocity.

Claims

1. A safety system for detecting faulty bearings of rollers supporting an endless belt conveyor, the system comprising an infra-red radiation sensor which is positioned, in use, adjacent the surface of the conveyor whereby changes in infra-red radiation of said surface may be sensed.

2. A safety system as claimed in claim 1 further comprising a shutter mechanism disposed between the sensor and the belt surface, whereby the sensor is switched between sensing the infra

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A safety system for a conveyor The present invention relates to a safety system for conveyors and has particular application to belt conveyors employing idler rollers. In certain applications of roller conveyors, e.g. in underground installations in coal mines, localised overheating of the rollers as a result of bearing seizure is of particular concern since this may be a serious fire risk. It will be appreciated that the detection of bearing seizure and overheating can prove difficult and time consuming where extensive conveyor runs are employed. Manual checking of each bearing on a regular basis would clearly be expensive in man hours, whilst the provision of a temperature probe for each bearing and associated monitoring circuitry would be extremely expensive in terms of both capital and installation cost as well as requiring unacceptable quantities of wire. It is an object of the present invention to provide a safety system for a conveyor by means of which roller overheating, for example as a result of bearing seizure, can be detected without the need for individual monitoring of each roller. According to the present invention there is provided a safety system for a conveyor in which an infra-red radiation sensor is used to sense changes in infra-red radiation from the conveyor surface. The invention provides a safety system for detecting faulty bearings or rollers supporting an endless belt conveyor, the system comprising an infra-red radiation sensor which is positioned, in use, adjacent the surface of the conveyor whereby changes in infra-red radiation of said surface may be sensed. The sensor responds to changes in belt temperature which occur for example as a result of the belt passing over a seized roller which necessarily increases in temperature due to frictional contact with the belt. The sensitivity of infra-red sensors is such that small changes in temperature can be detected and, by using a comparison technique, rises in belt temperature with respect to ambient temperature may be detected. According to another aspect of the invention, there is provided a method of detecting faulty bearings of rollers supporting an endless belt conveyor comprising locating an infra-red radiation sensor adjacent the surface of the conveyor in a position to sense the temperature of the conveyor surface, stopping the conveyor for a time to allow localised heating of the belt in the region of any roller having a faulty bearing, restarting the conveyor and moving it at a known. speed, sensing changes in temperature of the belt using the sensor and thereby identifying any localised heating of the belt surface, and measuring the elapsed time between restarting the conveyor and detecting the localized heating of the belt surface. Seizure of a bearing will cause the associated roller to run "hot", generating a hot spot on the belt. The location of the "hot" roller may be calculated by measuring the belt velocity and elapsed time for the "hot spot" to pass the sensor. One embodiment of the present invention will now be described hereinafter by way of example only. A roller conveyor comprises an endless belt entrained around spaced apart end rollers and a plurality of idler rollers for supporting a load carrying surface of the belt. The end rollers and idler rollers are supported in a frame by way of bearings. In order to detect hot running of the bearings, and hence possible bearing seizure, an infra-red sensor is located at a convenient point along the run of the belt conveyor. The sensor responds to a rate of change in infra-red radiation from the belt surface and when coupled with the necessary amplifiers and filter networks generates a voltage which can be used to create an audible or visual alarm signal. The safety system relies on heat generated at the roller as a consequence of bearing seizure, being transmitted to the belt of the conveyor, the transducer sensing an increase in the temperature of the belt. A shutter mechanism is provided as a reference whereby the sensor is mechanically switched between the shutter face and the belt so as to give an output signal corresponding to the temperature of the belt in relation to the ambient temperature of the shutter face. For example the shutter mechanism may comprise a disc driven by a small d.c. motor rotating at constant speed. The disc is placed adjacent the sensor and between the sensor and target. The disc has a hole in it so that the sensor is periodically exposed to the target during the period in which the hole is directly between the sensor and object. Thus the sensor responds with an output related to the difference in temperature between the shutter face and the target object in question. The location of the deflective roller/bearing may be determined by stopping the conveyor for a predetermined period allowing localised heating of the belt in the region of the defective roller. The conveyor is then re-started and the time taken for the hot spot on the belt to reach the sensor is measured. The position of the defective roller and/or bearing may then be calcuiated from elapsed time and the conveyor velocity. Claims

2. A safety system as claimed in claim 1 further comprising a shutter mechanism disposed between the sensor and the belt surface, whereby the sensor is switched between sensing the infra red radiation from a shutter face of the shutter mechanism, acting as a reference, and the infrared radiation from the belt surface.

3. A safety system as claimed in claim 1, in which the shutter mechanism comprises a rotatable disc which serves as the shutter face and which has an aperture therein which is aligned periodically with the sensor during rotation of the disc to expose the sensor to the belt surface.

4. A safety system for detecting faulty bearings of rollers supporting an endless belt conveyor constructed and adapted to operate substantially as hereinbefore described.

5. A method of detecting faulty bearings of rollers supporting an endless belt conveyor comprising locating an infra-red radiation sensor adjacent the surface of the conveyor in a position to sense the temperature of the conveyor surface, stopping the conveyor for a time to allow localised heating of the belt in the region of any roller having a faulty bearing, restarting the conveyor and moving it at a known speed, sensing changes in temperature of the belt using the sensor and thereby identifying any localised heating of the belt surface, and measuring the elapsed time between restarting the conveyor and detecting the localised heating of the belt surface.

6. A method as claimed in claim 5, further comprising comparing the temperature of the belt surface with that of a reference by switching the sensor between the belt surface and a shutter face of a shutter mechanism.

7. A method of detecting faulty bearings of rollers supporting an endless belt conveyor, substantially as hereinbefore described.