This application relates to a bearing arrangement, and particularly a self-aligning journal bearing for a rotary pump.
The load carrying capacity of conventional style journal bearings is limited by small deflections of a loaded shaft. Unfortunately, deflections, even small deflections, are unavoidable in such a mechanical device. In most instances, the shaft is held in as rigid a manner as possible in the housing. For example, a bearing assembly supports the shaft at one or more locations along the length of the shaft to provide adequate support of the shaft. Controlling or limiting the amount of deflection is important because too much shaft deflection results in operational issues with the rotary machine.
In this particular rotary machine application, i.e., a rotary pump, the drive shaft is rotated by a motor and transfers the rotary motion to the pump. The pump rotor imparts energy to the fluid in a well-known manner and thereby increases fluid pressure between the pump inlet and outlet. Misalignment of the rotor relative to stationary portions of the rotary machine can lead to severe deviations of the rotor or shaft and consequently non-uniform load bearing. Conventional journal bearings are sized to a specified or rated load-carrying capacity of the pump which necessarily entails designing the pump assembly as if uniform load bearing were to be achieved since the precise amount of misalignment can be estimated. Designers, of course, recognize that some imperfection or misalignment will exist and therefore purposefully accommodate or incorporate expected misalignment into the ratings for the pump.
However, improvements are needed in order to accommodate misalignment between the rotating and stationary components of the rotary machine, namely, the journal bearing and shaft, and thereby provide a better support structure that addresses the misalignment issue and its impact on the bearing assembly, and necessarily the design and performance of the rotary machine. There is also a need to minimize the weight and size of the pump, all in a manner that is economical, effective, and does not adversely impact the bearing assembly and operation of the rotary machine.