SUPPLEMENT LUBRICANT FREE PNEUMATIC MOTOR

Abstract

The present invention provides a pneumatic motor having a motor body having an air inlet and an air outlet, at least one rotor mounted in a chamber of the motor body and adapted to be driven by compressed air fed into the air inlet and an adhesive lubricant applied to the at least one rotor, the lubricant being sufficiently adhesive to remain substantially adhered to the at least one rotor under operational speeds in excess of 13500 rpm.

Description

TECHNICAL FIELD

The present invention relates to a pneumatic motor. The invention has been developed primarily for use in underground mining and tunnelling tools, such as a roofbolter, and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. Other applications include motors for processing equipment in the food and pharmaceutical industry, in which contamination-free process equipment is required.

BACKGROUND OF THE INVENTION

Pneumatic motors use rotors driven by compressed air and are common in power tools and other machinery. Pneumatic motors using very clean and dry air can be operated without supplementary lubrication. However, most pneumatic motors require supplementary lubrication to function reliably with durability. The supplementary lubrication is fed into the compressed air stream by a controlled drip rate of oil relative to the supplied airflow. All the components exposed to the compressed air are then coated with a film of oil.

In mining and construction, pneumatic motors rely more heavily on the supplementary lubrication to combat compressed air that can be highly contaminated with contaminants such as water, rock and coal. Without the supplementary lubrication, corrosion and fouling of internal components can render the equipment inoperable in a short time.

The lubricators which feed oil into the airflow are generally unreliable and often result in too little or too much oil being fed in. As noted above, lack of oil feed will reduce the operational life of the equipment. Excessive oiling reduces the performance of the equipment due to the sludging of internal components. Excessive oiling can also render the equipment inoperable.

The responsibility for maintaining oil supply to the lubricators generally falls to the operators, who, in practice, rarely check the lubricator oil level and often operate equipment without sufficient oil. A lubricator without sufficient oil can also act as a water trap which results in water being fed into the air stream and the misconception that the lubricator is full of oil.

Further, equipment with motors having supplementary lubrication expel a fine mist of oil with their exhausted air. This can be detrimental to the health of operators who inhale the contaminated air and creates a potential occupational health and safety liability.

OBJECT OF THE INVENTION

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art, or to provide a useful alternative.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a pneumatic motor having:

a motor body having an air inlet and an air outlet;

at least one rotor mounted in a chamber of the motor body and adapted to be driven by compressed air fed into the air inlet; and

an adhesive lubricant applied to the at least one rotor, the lubricant being sufficiently adhesive to remain substantially adhered to the at least one rotor under operational speeds in excess of 13500 rpm.

Preferably, the at least one rotor includes a drive rotor and an idler rotor. Further preferably, the rotors are mounted on sealed cage deep groove ball bearings.

In a preferred embodiment, the motor body is constructed from corrosion resistant material. Preferably, the motor further includes a reduction gearbox having a gearbox body constructed from a corrosion resistant material. Preferably, the corrosion resistant material comprises nylon, stainless steel or acetyl resin engineering plastic.

In an optional embodiment, the motor is adapted for bidirectional rotation and the air inlet and air outlet are selectively interchangeable.

In a preferred embodiment, the motor body includes internal baffling formed in the motor body and associated with the air outlet, the baffling being adapted to muffle motor noise. Preferably, the motor body comprises a wall surrounding the chamber and the baffling is provided in a conduit formed within the wall, the conduit providing fluid communication between the chamber and the air outlet. Further preferably, the baffling is provided by the conduit following a corrugated path within the wall. Optionally, the conduit extends around the wall, substantially circumventing the chamber.

Preferably, the adhesive lubricant is Optimol Paste White T Spray (trade mark), marketed by Castrol.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings wherein:

FIG. 1 is a side view of an embodiment of a motor according to the invention;

FIG. 2 is a front view of the motor depicted in FIG. 1;

FIG. 3 is an open top view of the motor of FIG. 1;

FIG. 4 is a perspective view of the motor of FIG. 1, showing internal detail; and

FIG. 5 is a top view of the motor of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, FIGS. 1 to 5 depict an embodiment of a motor 10 according to the present invention. The motor 10 comprises a motor body 12, having an air inlet 14 and an air outlet 16. The motor body 12 has a chamber 15 in fluid communication with the air inlet 14 and air outlet 16. The chamber 15 houses a steel alloy drive rotor 18 on a drive shaft 20 and a steel alloy idler rotor 22, intermeshed with the drive rotor 18, on an idler shaft 24. Each shaft 20, 24 is mounted on sealed cage deep groove ball bearings (not shown). A conduit 25 extends from an opening 26 to the air outlet 16. The conduit 25 is formed within the wall of the motor body 12, extending around the periphery of the chamber 15 and following a corrugated path.

During construction of the motor 10, the rotors 18, 22 are sprayed with an adhesive lubricant such as Optimol Paste White T Spray (trade mark) marketed by Castrol. The lubricant is sufficiently adhesive to remain adhered to the rotors 18, 22 under operational speeds in excess of 13500 rpm.

In operation, compressed air is fed into the air inlet 14. Since the intermeshed rotors 18, 22 prevent air passing between the rotors 18, 22, the air is forced around the periphery of the rotors 18, 22. As the air flows between the rotors 18, 22 and the wall of the motor body 12, the air drives the two rotors 18, 22 to rotate in the direction indicated by the arrows.

The air then exits the chamber 15 via the opening 26 and flows along the corrugated conduit 25 around the periphery of the chamber 15 before being expelled via the air outlet 16. As the air travels along the conduit 25 noise energy is absorbed into the wall of the motor body 12 and the noise output at the air outlet 16 is reduced.

Since the adhesive lubricant adheres to the rotors 18, 22 at normal operational speeds, the motor 10 doesn't require supplementary lubrication. This results in cleaner exhaust, less maintenance and more reliable performance.

The motor body 12 is advantageously constructed from corrosion resistant material such as nylon, stainless steel or acetyl resin engineering plastic, such as polyoxymethylene. This construction provides a light weight motor that is not susceptible to corrosion when used in contaminated environments.

The motor 10 can also be configured to operate selectively in forward or reverse, i.e. bidirectional rotation. When the motor is operated in reverse, the air inlet becomes the air outlet and vice versa. This feature is particularly advantageous in applications of the motor in the food and pharmaceutical industry.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in other forms.

Claims

1. A pneumatic motor having:

a motor body having an air inlet and an air outlet;

at least one rotor mounted in a chamber of said motor body and adapted to be driven by compressed air fed into said air inlet; and

an adhesive lubricant applied to said at least one rotor, said lubricant being sufficiently adhesive to remain substantially adhered to said at least one rotor under operational speeds in excess of 13500 rpm.

2. The motor of claim 1, wherein said at least one rotor includes a drive rotor and an idler rotor.

3. The motor of claim 1, wherein said rotors are mounted on sealed cage deep groove ball bearings.

4. The motor of claim 1, wherein said motor body is constructed from corrosion resistant material.

5. The motor of claim 1, wherein said motor further includes a reduction gearbox having a gearbox body constructed from corrosion resistant material.

6. The motor of claim 4 wherein the corrosion resistant material comprises nylon, stainless steel or acetyl resin engineering plastic.

7. The motor of claim 1, wherein the motor is adapted for bidirectional rotation and the air inlet and air outlet are selectively interchangeable.

8. The motor of claim 1, wherein said motor body includes internal baffling formed in said motor body and associated with said air outlet, said baffling being adapted to muffle motor noise.

9. The motor of claim 8, wherein said motor body comprises a wall surrounding said chamber and wherein said baffling is provided in a conduit formed o within said wall, said conduit providing fluid communication between said chamber and said air outlet.

10. The motor of claim 9, wherein said baffling is provided by said conduit following a corrugated path within said wall.

11. The motor of claim 9, wherein said conduit extends around said wall, substantially circumventing said chamber.

12. The motor of claim 1, wherein the adhesive lubricant is Optimol Paste White T Spray (trade mark).