GB2042095A

GB2042095A - Lubrication of sliding contact bearings

Info

Publication number: GB2042095A
Application number: GB7942626A
Authority: GB
Original assignee: Instytut Mechaniki Precyzyjnej
Current assignee: Instytut Mechaniki Precyzyjnej
Priority date: 1978-12-22
Filing date: 1979-12-11
Publication date: 1980-09-17
Also published as: IT1164817B; IT7951150A0; FR2444842A1; DE2933316A1; PL212032A1

Abstract

With the supply of liquid lubricant to the sliding surface of a bearing effected through ducting discharging through an opening in the surface, a continuous supply with minimum flow resistance is assured by providing the ducting with a discharge portion whereof a convexly curved internal wall surface diverges towards and merges with the sliding surface. In a particularly effective embodiment the internal profile of the discharge portion of the ducting, as produced by sectional planes cutting symmetrically in the direction of discharge, has the form of an oval curve which is convex inwards, varies monotonically, and joins tangentially with the sliding surface. The curvature may be determined by an equation of a clothoid or of a trigonometric function, or may be a sinusoidal or exponential curve. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the lubrication of slide bearings This invention relates to the lubrication of slide bearings and is particularly concerned with improving the supply of liquid lubricant to the sliding surfaces of the bearings by means of supply ducting such for example as lubricating channels having any form of cross-section, holes, grooves, pockets or slots and any combination of said holes, grooves, pockets or slots.

There are known slide bearings wherein the surfaces of the side walls of lubricating channels connect immediately with the sliding surfaces of the bearing to form sharp edges which are disadvantageous as regards the continuity of flow of the lubricating liquid due to occurrence of sudden changes in the pressure of said liquid. The troubles in the inflow of the lubricating liquid to the sliding surface of the bearing result first of all in a reduction in the hydrodynamic capacity of the bearing and thus to increased friction, and secondly to cavitation erosion as a result of the increase in the pressure gradient.

In other slide bearings, known for instance from the FRG Patent Application No. 1182906 or from the U.S. Patent Specification No. 3663072, the surfaces of the side walls of the lubricating channels are connected with the sliding surfaces of the bearing through the intermediation of outlet or discharge surfaces formed as one or several conical surfaces.

From FRG Patent Applications Nos. 2537046 and 2352750 there are also known slide bearings wherein the surfaces of side walls of lubricating pockets connect with the sliding surfaces to produce sharp edges.

From the FRG Patent Application No. 1279499 it is known to provide a bearing wherein in the lubricating groove formed in the sliding surface is shaped in the form of a gapped divergent cylindrical surface, while according to the Polish Standard PN-75/ M-871 Os the surfaces of outlet walls of lubricating grooves are determined by means of radii which depend on the dimensions of the grooves. Each of the above-mentioned configurations of the outlet surfaces of the lubricating channels facilitates to a smaller or greater extent the through-flow of the lubricating liquid, but does not solve the problem completely, since in each of said cases into the stream of the lubricating liquid edges protrude which hinder the flow of the liquid.

The object of the invention is to shape the surfaces of the outlet portions of lubricating ducting in such way as to provide for an uninterrupted supply of lubricating liquid into the working clearance of the bearing with minimum flow resistances and with uniform covering of the entire sliding surface of the bearing.

According to the present invention we provide a slide bearing including a sliding surface and liquid lubricant supply ducting communicating with the sliding surface through an opening therein and having a discharge portion whereof a convexly curved internal wall surface diverges towards and merges with the sliding surface.

Preferably the internal profile of the discharge portion of the ducting, as produced by sectional planes cutting symmetrically in the direction of discharge, has the form of an oval curve which is convex inwards, varies monotonically, and joins tangentially with the sliding surface.

Preferably also the curve is clothoid. However, the curve may be determined by an equation of a trigonometric function, or may be a sinusoidal or exponential curve.

Preferably also the smoothness of outlet surfaces of the lubricating channels is approximated to that of sliding surfaces of the bearings.

Such edgeless shaping of the outlet surfaces of the lubricating ducting reduces substantially the flow resistances of the lubricating liquid, and the smooth, tangential connection of said outlet surfaces with the bearing sliding surfaces provides for the uninterrupted flow of the liquid in the form of a film having constant thickness. Such lubrication secures a long life for the bearings, especially for highly loaded ones. The uniform and continuous wetting of the bearing improves also the conditions for the cooling of the bearing.

An exemplary embodiment of the invention will now be described more particularly with reference to the accompanying drawing wherein: Figure 1 is a cross-sectional view of a portion of the bearing with lubricating ducting having the form of a cylindrical hole; Figure 2 is a longitudinal sectional view of the bearing with lubricating ducting in the form of two holes and lubricating groove; Figure 3 is a longitudinal sectional view of a bearing with lubricating ducting having the form of a lubricating channel; and Figure 4 is a front view fo the bearing shown in Figure 3.

Referring to the drawings: In a bearing 1 with a sliding surface 2, the lubricating ducting is made in the form of a cylindrical hole 3 with its axis perpendicular to the longitudinal axis of the bearing. The wall surface 4 of the hole 3 is connected with the sliding surface 2 of the bearing 1 through the intermediation of a discharge or outlet surface shaped so that the longitudinal section lines of said outlet surface show the form of a curve Y described by the equation of a clothoid, said lines connecting tangentialiy with the sliding surface 2 of the bearing 1.

When the lubricating ducting is made in the form of two holes 3 and an annular groove 5 in registry with the holes 3 and formed in the sliding surface 2 in a plane perpendicular to the longitudinal axis of the bearing, the longitudinal section lines of the outlet or discharge surfaces of the groove 5 follow a curve Y determined by a clothoid equation. The outlet surfaces of the holes 3 connect with the outlet surfaces of the groove 5.

In the case when the lubricating ducting made in the sliding surface 2 has the form of a channel 6 parallel to the longitudinal axis of the bearing, then the curve Y determined by a clothoid equation is followed by cross-sectional lines on the outlet or discharge surfaces of the channel 6. The outlet surfaces can also be formed in such a way that relevant section lines thereon follow a sinusoidal or an exponential curve.

The outlet surfaces of lubricating ducting, determined by said equations, always connect tangentially with the sliding surface 2 of the bearing 1, and as far as possible also tangentially to the side surfaces of said ducting. The smoothness of said outlet surfaces approximates to that of the sliding surface 2 ofthe bearing 1.

We have developed a practical and economical method offorming said outlet surfaces according to the invention.

Claims

1. Aslide bearing including a sliding surface and liquid-lubricant supply ducting communicating with the sliding surface through an opening therein and having a discharge portion whereof a convexly curved internal wall surface diverges towards and merges with the sliding surface.

2. A bearing according to claim 1, wherein the ducting includes a through bore and the annular surface of the discharge portion of the through bore flares in a convex curve towards and merges with the sliding surface.

3. A bearing according to claim 1, wherein the sliding surface is a tubular bore and the ducting includes an annual discharge groove formed in the bore and having its opposed side walls flared in convex curves towards and merging with the bore surface.

4. A bearing according to claim 1, wherein the sliding surface isa tubular bore, and the ducting includes an axial discharge groove whereof the opposed side walls flare in opposed convex curves towards and merge with the bore surface.

5. A bearing according to any one of the preceding claims, wherein the internal profile of the discharge portion of the ducting, as produced by sectional planes cutting symmetrically in the direction of dishcarge, has the form of an oval curve which is convex inwards, varies monotonically, and joins tangentially with the sliding surface.

6. A bearing according to any one of claims 1 to 5, wherein the smoothness of the internal wall surface of the discharge portion is approximately that of the sliding surface.

7. A bearing according to any one of claims 1 to 6, wherein the form of the curve of the convexly curved surface of the discharge portion is determined by an equation of a clothoid.

8. A bearing according to any one of claims 1 to 6, wherein the form of the curve of the convexly curved surface of the discharge portion is determined by an equation of a trigonometric function.

9. A bearing according to any one of claims 1 to 6, wherein the convexly curved surface of the discharge portion has the form of a sinusoidal or an exponential curve.

10. A slide bearing substantially as hereinbefore described with reference to Figure 1 or Figure 2 or Figures 3 and 4 of the accompanying drawings.