GB2232091A

GB2232091A - Debris monitoring apparatus

Info

Publication number: GB2232091A
Application number: GB8912022A
Authority: GB
Inventors: Colin Darrell Taylor
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1989-05-25
Filing date: 1989-05-25
Publication date: 1990-12-05
Also published as: GB8912022D0; AU5574290A; DE9005586U1; DE4015782A1

Abstract

Lubricating fluid is continuously sampled from the return line (Fig. 1) and fed by a pump 7 to a cartridge membrane filter 9. The membrane filters out particles from the fluid and discharges the fluid through a volume meter 13 back to the fluid reservoir 1. The cartridge can be removed from the apparatus for analysis. Apparatus also includes a heater 8, pressure gauge 17, pressure-operated by-pass valve 18 and valves 10, 12 operable to by-pass the filter 9, e.g. during filter replacement, and to obtain a fluid sample at 16. <IMAGE>

Description

Debris Monitoring Apparatus This invention relates to debris monitoring apparatus for monitoring the amount of debris collected in fluid circulating in a machine or a fluid system.

In many forms of mechanical apparatus, such as gear boxes which are oiled and cooled by a fluid, it is a known technique to monitor the state of the fluid to determine the health and condition of the apparatus. For example, if a gear box is starting to wear, small particles of metal from the teeth of the gear can be chipped off and carried into the lubricating oil of the gear box. The amount of debris accumulated in the oil can be used as an indication as to the wear of the machine and can be used as an indication as to when the machine should be replaced.

It is particularly useful, if a rate of wear is taking place which indicates that the machine will last a little while longer, for the replacement or the maintenance of the machine to take place at a time which is convenient to the operator of the machine. For example, a machine may be kept operating through a working week and may be stripped down and maintained during a weekend.

A number of techniques and apparatus for monitoring the condition of the fluid in a machine have already been proposed and these include simple arrangements whereby a sample is taken at intervals from a sump or a reservoir of a machine and the sample is then analysed and a count made of the wear particles after the sample has been passed through a filter. By comparing samples over a period, any change in the pattern of wear and an increase in particles can be noted and predictions made as to the health of the machine.

A more sophisticated method of monitoring the liquid is by having an on-line tape style filter element in a discharge pipe. Fluid from the machine is passed through this filter tape.

The particles in the oil are filtered out onto the tape and the tape is replaced regularly by advancing it through the monitoring apparatus. Each part of the tape is then marked with a time and analyses can be made of the tape for comparative purposes.

Unfortunately, this type of continuous monitoring device is very expensive and sophisticated and is therefore not applicable to applications where cost and a rough environment are likely to be material factors in deciding on the type of monitoring system to be adopted.

Where particle counts of debris and information on the nature of the debris in the fluid is required this can usually only be done in laboratory conditions away from the site in which the machine is operating. This means that the filter has to be taken under conditions which do not permit any contamination of the filter membrane to take place. With a tape type of filter, this is not always possible and there is a high risk of contamination from outside sources.

It is an object of the present invention to provide and improve debris monitoring apparatus which is able to operate continuously and which can give samples of the debris collected which can be analysed either on site or remote from the site without any substantial risk of contamination.

According to the present invention, there is provided debris monitoring apparatus arranged to receive a supply of fluid from a machine, pump means for extracting continuously a sample at a steady rate from the machine fluid, a cartridge membrane device arranged to filter the sampled fluid and volume measuring means for determining the volume of fluid sampled over a period.

The apparatus may also include a pressure indicating device to enable the pressure at which the fluid is delivered from the sample to be monitored. Further, a thermostatically controlled fluid heater may be included to ensure that the viscosity of the fluid supplied to the filter is not excessively high.

Pressure relief valve means may also be incorporated in the circuit of the apparatus to ensure that the pressure of the fluid supplied to the filter does not become excessively high. A by-pass valve may be included so that the cartridge may be removed from the apparatus and replaced without there being any interruption in the flow of fluid, and so that the apparatus maybe substantially purged using fluid without passing it through the cartridge filter.

In order that the invention may be readily understood, one example of debris monitoring apparatus in accordance with the present invention will now be described with reference to the two figures of the accompanying drawings.

In the drawings, figure 1 indicates a reservoir tank of a mining machine and figure 2 is a schematic view of the circuit diagram of the apparatus of the invention.

Referring now to the drawings, the machine (not shown) is oil lubricated and oil is drawn from a reservoir tank 1 and fed to the machine from where it is pumped round and returned to the tank 1 via a pipe 2. The pipe 2 has its free end extending below the level of oil 3 in the tank 1. Adjacent to this free end a conduit 4 is inserted through a gland 5. The conduit feeds a sample of the oil returned from the machine to the apparatus of the invention as shown in figure 2 via a non return valve 19. The rest of the oil returned is discharged into the reservoir 1.

Turning now to figure 2, this comprises basically a cabinet 6 which contains a diaphragm pump 7, having an electric clock. The conduit 4 connects directly with the pump 7 and the pump 7 draws the oil from the pipe 2. The pump 7 then discharges into a thermostatically controlled oil heater 8 which, in this example, is adjustable up to a temperature of 60 degrees centigrade. This is to ensure that the oil viscosity is not excessively high when it is passed to a cartridge filter 9 via a by-pass valve 10. The cartridge filter 9 is connected through a non-return valve 11 to a further by-pass valve 12 to a volume meter 13. From here the sample is returned via a conduit 14 to the tank 1.

In operation, the lubricating oil is constantly circulated around the machine and is drawn off via the pipe 2. A sample is continuously taken via conduit 4 and pulled through the pump 7 and fed to the membrane of the filter 9. Any particles in the oil being sampled are retained on the membrane of the filter and the oil is then passed back to the tank through the volume meter 13 which indicates over a period the quantity of oil which has been sampled.

After a set period, say 24 hours, the cartridge filter 9 is removed and a fresh filter is inserted. The filter is then taken away for analysis, such as particle count and elemental analysis, so that a decision can be made on the condition of the machine.

In order to purge the apparatus or to replace the filter cartridge without interrupting the operation of the machine, the by-pass valve 10 is moved to a position to divert the oil from the heater 8 along a circuit 15 and to the by-pass valve 12 and thus back to conduit 14. The non-return valve 11 prevents any leakage back of the oil into the filter 9.

The by-pass valve 12 can at any time be operated to its alternative position to enable a physical sample of the oil to be collected at a sampling point 16. The oil sample will be either filtered through the filter 9 or not filtered depending on the position of the by-pass valve 10.

A pressure gauge 17 is included on the output side of the pump 7 to give an indication of the pressure at which the sample oil is being presented to the filter. A pressure relief valve 18 ensures that the oil pressure does not become excessively high. In this example, this is a pressure of between 7 and 10 bar.

The non return valve 19, sited at the tank end of the suction pipe will prevent air entraining into the suction pipe and then caving the pump to cavitate if left switched off for long periods.

The present invention provides a debris monitoring apparatus which is simple and reliable to use and which enables a filter to be removed from the apparatus with the minimum of effort and without any interruption in operation. The membrane of the filter is not likely to be subject to any extraneous contamination and can be examined either on site or remotely, according to the convenience of the operation.

The whole apparatus is relatively simple and thus is inexpensive compared with previously available on-line monitoring devices.

Claims

1. A debris monitoring apparatus arranged to monitor samples of fluid from a machine comprises pump means for extracting continuously samples of the fluid at a steady rate, a cartridge membrane device arranged to filter the sampled fluid and volume measuring means for determining the volume of the sampled fluid over a period.

2. Apparatus as claimed in claim 1 and including a pressure indicating device.

3. Apparatus as claimed in claim 1 or claim 2 and including a thermostatically controlled fluid heater.

4. Apparatus as claimed in any preceding claim and including a fluid pressure relief valve.

5. Apparatus as claimed in any preceding claim and including a fluid by-pass valve for the cartridge membrane device.

6. Apparatus as claimed in claim 5 and including a non-return valve associated with the output of the cartridge membrane device.

7. Apparatus as claimed in any preceding claim and including a non-return valve associated with the input to the debris monitoring apparatus.

8. Apparatus as claimed in any preceding claim and including a by-pass valve adapted to supply samples of filtered fluid to a sampling point.

9. Debris monitoring apparatus substantially is hereinbefore described and with reference to the accompanying drawings.