SHAFT BEARING ASSEMBLY

Abstract: It is well-known that grease over-filling of a bearing housing provides a strong rise of the normal running temperature of the bearing. In order to avoid this problem the grease surplus has to be drained out through an escape hole of the housing. On the long run this leads also to a harmful loss of useful base-oil from the lubricant. The claimed design overcomes this problem by applying a thermally controlled grease escape valve (6, 12) in the escape hole of the housing (1). This valve (6, 12) opens when an undisereable rise of temperature occurs and closing itself when the temperature drops to an acceptable level. Preferably the valve (6, 12) is controlled by a temperature-­ memory-spring (10) which releases itself only when the surrounding temperature exceeds a threshold value.

Description: The invention relates to a shaft bearing assembly comprising a housing having one or more rolling bearings therein, through which a shaft protrudes on at least one side, which housing is provided with sealing means acting on the shaft as well as with an inlet opening for supply of lubricant,an outlet opening for excess spent lubricant and wherein a temperature-sensitive outlet valve is arranged. Such a bearing assembly is disclosed by the British patent GB-A-781618. According to this known assembly superfluous lubricant is released via a mechanical spring actuated valve. The invention seeks to provide a fast reacting and much better controllable operating solution to the problem, and to that end is characterised in that said outlet and inlet openings are arranged on each side of the rolling bearings and in that said temperature-sensitive outlet valve having a valve housing comprises a temperature-memory spring due to which said valve opens and closes at predetermined temperatures. This invention is generally very useful when automatic lubrication systems are applied e.g. rows of bearing assemblies which support a (long) shaft. According a preferably embodiment, a valve body is connected to the temperature-memory-spring which body is provided with a sealing member that can co-operate with the valve housing. Further, in certain applications of the bearing assembly it may be desirable to be able to register afterwards that the outlet valve was open in service because of an elevation of temperature. For this purpose the outlet valve is provided with an indicator consisting of a chemical element or a coating layer that changes colour when the temperature rises above a predetermined threshold. In case of limited space or poor visibility, it may be advantageous when the outlet valve is arranged in a separate adapter which fits in the bearing housing. It may be noted that likewise in case of a deficiency of lubricant a temperature rise might occur whereby the outlet valve would be opened. However, this situation hardly will arise in practise because an excess of lubricant is more likely to occur than a deficiency. The invention will now be further illustrated with reference to embodiments represented by way of example in the drawing, where: Fig. 1 shows a longitudinal section of a shaft bearing assembly to which the invention may be applied, and Fig. 2 shows a detail of Fig. 1, to a larger scale, having an outlet valve according to the present invention accommodated in the bearing housing. The figures show a shaft bearing assembly 1 consisting of a bearing housing 2 in which a rolling bearing 3 is installed. The housing 2 is further equipped with sealing means 4 acting on the shaft 5. These sealing means 4 may for example consist of felt rings, oil sweep rings, lip seals, labyrinth seals and the like. The outlet valve 6, shown specifically in Fig. 2, consists of a valve body 7, which may be provided with a sealing member 8. In the closed state of the outlet valve 6, the valve member 7 is in sealing contact with a valve housing 9. The valve member 7 is actuated by intervention of a temperature-sensitive element 10, for example a thermostat element or a "temperature memory spring." Preferably the valve member 7 and the valve housing 9 are in different, contrasting colors. The valve member 7 may be further equipped with an indicator 11 indicating that the temperature of the outlet valve reached a value at which the valve opened. The outlet valve need not be installed directly in the bearing housing 2, as represented in Fig. 2, but may alternatively be installed in an adaptor 12. The adaptor 12 is shown in Fig. 1, in which figure a lubricant supply nipple is designated by 13.

Claims: Shaft bearing assembly (1) comprising a bearing housing (2) having one or more rolling bearings (3) therein, through which a shaft (5) protrudes on at least one side, which housing is provided with sealing means (4) acting on the shaft (5) as well as with an inlet opening for supply of lubricant, an outlet opening for excess spent lubricant and wherein a temperature-sensitive outlet valve (6) is arranged, characterised in that said inlet and outlet openings are arranged on each side of said rolling bearings (3) and in that said temperature-sensitive outlet valve (6) having a valve housing (9) comprises a temperature-memory spring (10) due to which said valve (6) opens and closes at predetermined temperatures. A bearing assembly according to claim 1, characterised in that to said temperature-memory-spring (10) a valve body (7) is connected provided with a sealing member (8) which co-operates with the valve housing (9). A bearing assembly according to claim 1 and 2, characterised in that said outlet valve (6) is provided with an indicator (11) consisting of a chemical element or a coating layer that changes colour when the temperature rises above a predetermined threshold. A bearing assembly according to any of the preceding claims, characterised in that said outlet valve (6) is arranged in a separate adapter (12) which fits in said bearing housing (2).

Inventors: DOLFSMA, HENDRIK, GABELLI, ANTONIO
Applicants: SKF INDUSTRIAL TRADING & DEVELOPMENT CO, B.V.
Application year: 1988
Main classification: F16C33
IPC codes: F16N29, F16C33, F16C35, F16C23