AU2004200795A1 - Bearing housing - Google Patents

Description

Regulation 3.2 -1-

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT APPLICANT: Scott Greaves NUMBER: FILING DATE: Invention Title: BEARING HOUSING The following statement is a full description of this invention, including the best method of performing it known to me: BEARING HOUSING Area of the Invention This invention relates to the area of industrial machinery and in particular to bearing housings for motor driven apparatus. While the housing of the invention has many applications, for convenience's sake, it will be discussed herein in terms of its application between a motor and industrial fan.

Background to the Invention A motor driven industrial fan assembly conventionally includes a coupling between the motor and the fan. The fan impeller shaft being supported on bearings.

Spherical roller bearings or self aligning ball bearings are normally used to accommodate the radial and axial loads imposed by the impeller weight and the aerodynamic fan forces. They are each housed in a plummer block type bearing housing. Each fan assembly incorporates two bearings and two housings. The bearings are normally grease lubricated.

Conventional spherical roller bearings used in housings associated with industrial fans generally have a very limited life as the vibration of the fan impeller can cause bearings which are used to maintain a drive shaft in axial and radial relation with the fan to deteriorate. This is due to the circumferential wear between the bearing outer ring and the housing bore.

WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 3 It is in fact known for the bearing roller elements to skid relative to the inner and outer ring raceways when subjected to a combination of light loads, high speeds and grease lubrication, thereby causing damage to the bearing rolling elements, inner ring raceway and outer ring raceway. The result is a greatly reduced bearing service life.

In addition bearing housings have traditionally been assembled on site and as such are subject to problems of increased wear due to contaminant intrusion into the housing during assembly.

Outline of the Invention It is an object of this invention to ameliorate these problems by providing bearing means in a housing which does not have the problems of conventional bearings or of conventional assembly.

The invention is a bearing housing which housing is manufactured integrally and includes a drive shaft passing therethrough and bearing means which are oil lubricated in situ.

It is preferred that the bearing means be tapered roller bearings.

It is further preferred that the bearing means be lubricated by means of an oil sump within the housing.

WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 It is preferred that the housing be provided with means to maintain a constant oil level within the housing.

It is further preferred that the housing of the invention be assembled complete with its bearings in a clean environment and that it be able to be connected between a motor and a device such as an industrial fan as an integral sealed unit.

In order that the invention may be more readily understood we shall describe by way of non limiting example a particular embodiment of the invention.

Details of the Drawing Figures Fig. 1 shows a longitudinal cross-section through the bearing housing; Fig.2 shows a cross-sectional view of the bearing housing viewed from the fan end of the housing; Fig. 3 is a perspective view of the bearing housing; Description of an Embodiment of the Invention In a preferred embodiment of the invention an integral housing 1 and bearing combination for a drive shaft is provided. The housing has a body 30 which is a substantially sealed unit having a shaft 8 passing there through, the shaft 8 having a first end 31 adapted to engage with an industrial fan impeller and an opposing WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 end 32 adapted to couple to a motor drive mechanism. At either end of the housing an automatic greaser 13 is provided.

The housing body is provided with means to attach it to an underlying surface, in this case by means of bolts 34 through lateral flanges 33.

At either end of the body an end cap 3 is provided which is located about the shaft and attached to the body by means of cap screws 6.

Internally to the housing are tapered roller bearings 2 extending in an angled fashion from a point of abutment with the interior of the body to oil seals 5 whose lip seals run on a hardened wear sleeve 4 about the periphery of the shaft The wear sleeve 4 being provided to eliminate grooving of the shaft, the wear sleeves being easily replaceable when the bearings are being replaced.

The tapered roller bearings 2 are better able to withstand the axial load from the suction forces of the fan impeller as well as radial loads.

Lubrication is provided by oil 40 located in the base of the housing which is contacted by the bearings as they rotate. The oil level 41 is maintained, should the need arise, by means of the provision of a constant level oiler 12 at one side of the unit. The unit is also provided on an opposing side with an oil level site gauge 42 or an oil level window. The unit can also include a low oil level float switch and a bearing temperature probe as a customer option.

WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 Internal pressurisation and hence seal leakage is eliminated by the fitting of baffle type breather 10, or alternatively an expansion chamber, on top of the housing as is oil filler cap 11. The precise location of these devices with respect to the housing is however immaterial.

When bearings are in continuous service 24 hours a day, the properly maintained oil lubrication provided ensures that the bearings will run reliably for their maximum design life. The lubrication also reduces the chance of roller skidding occurring under light loads which can occur when grease lubricated tapered roller bearings are used. The large volume of oil ensures better heat dissipation and hence better cooling than grease lubricated bearings.

Another problem associated with the use of spherical rollers is the bearing creep due to vibration forces present in the fan impeller as both the floating and fixed bearing are always clearance fits in each housing. This results in outer ring creep and eventual housing bore wear.

The housing bores of the invention are line bored and toleranced to provide a slight interference fit on the bearing cup at the impeller end therefore the bearing creep is eliminated. The motor end bearing cup must be a clearance fit in the housing to allow for thermal expansion of the shaft. It does not suffer the same vibrational load as the impeller end bearing due to the reduced moment load.

WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 In addition disc springs are fitted to milled slots in the end cap of the housing at the motor drive end to allow axial spring loading against the bearing cup back face.

Each disc spring is supported by a light helical compression spring and a dowel pin to facilitate ease of assembly. This addition acts to ensure positive roller and raceway contact around the entire circumference of both the cup and cone raceways. This reduces cage stress and eliminates all radial and axial clearance and reduces circumferential creep of the cup on the motor end bearing to extend both bearing and seal life.

Outer labyrinth rings are provided on the shaft and spring type or gas generating type greasers 13 are fitted to keep contaminants away from the lip seal area. This greatly extends the seal life particularly in arduous conditions.

The bearing housing of the invention is unique in that it is a bearing housing using tapered roller bearings. It has the further advantage as described of providing a one piece oil lubricated housing which is substantially free from contaminants.

While we have described herein one particular embodiment of the invention it is to be understood that variations and modifications in the materials used and the features described can still lie within the scope of the invention.

WP51\BARBARA\GREFAVES-SPC\BV\27 February, 2004

Claims (7)

1. A bearing housing which housing is manufactured integrally and includes a drive shaft passing therethrough and bearing means which are oil lubricated in situ.

2. A bearing housing as claimed in claim 1 in which the bearing means are tapered roller bearings.

3. A bearing housing as claimed in claim 1 or claim 2 wherein the bearing means is lubricated by means of an oil sump within the housing.

4. A bearing housing as claimed in claim 3 wherein the housing is provided with means to maintain a constant oil level within the housing.

A bearing housing as claimed in claim 4 wherein the housing of the invention is assembled complete with its bearings in a clean environment and is able to be connected between a drive means and a driven device as an integral sealed unit.

6. A bearing housing as claimed in claim 5 wherein the drive means is a motor and the driven device is an industrial fan.

7. A bearing housing substantially as herein described by reference to the accompanying drawings. WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004 DATED THIS 27 lh DATEDTHIS27thDAY OF FEBRUARY 2003 SCOTT GREAVES By his Patent Attorneys A TATLOCK ASSOCIATES WP51\BARBARA\GREAVES-SPC\BV\27 February, 2004