Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Patent
1995-06-05
1996-12-17
Denion, Thomas E.
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
4151691, 184 623, 184 64, F01D 112
Patent
active
055846505
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a lubrication system comprising a pump which pumps lubrication oil from a reservoir and delivers it to equipment to be lubricated.
A common problem with lubrication systems is that of air in the lubrication oil which can impair performance of the pump and reduce the delivery rate of oil to the equipment. This problem is overcome by providing an air/oil separator in the system, which in the case of aerospace systems, commonly comprises a cellular metallic filter body through which the oil is fed as the body is spun. The filter body is mounted on a shaft with a scavenge pump which feeds the lubricating oil from the reservoir to the filter body. A gear pump then takes the de-aerated supply of lubricating oil from the scavenge pump and delivers this under pressure to the equipment. The gear pump is driven at a different speed to the scavenge pump, and is mounted on a separate drive shaft. A pressure relief valve is connected in the lubrication circuit of the gear pump, together with a particulate filter to protect the pump. These known aerospace lubrication systems are therefore relatively complicated an costly to manufacture, and trend to be heavy, which is generally a serious disadvantage of any aerospace equipment.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an improved lubrication system suitable for aerospace applications.
This is achieved according to the invention by providing a lubrication system comprising a first pump means to deliver lubricating oil from a reservoir to equipment to be lubricated, a second pump means to return lubricating oil from the equipment to the reservoir, and characterised in that both pump means are mounted on a common drive shaft and each comprises a regenerative type pump means with the second pump means having an air bleed connected to the reservoir from an inner region of the pump impeller in which air accumulates.
A regenerative type pump has an impeller with a plurality of blades forming a series of cells spaced angularly around the axis of rotation of the impeller, and a housing with a flow channel extending between a pump inlet and pump outlet including a guide channel located alongside the impeller so that the cells open laterally of the plane of rotation of the impeller into the guide channel and cooperate therewith to induce a spiral or helical flow of fluid through the guide channel and cells along the length of the flow channel as the impeller rotates. The term "regenerative type pump" and "regenerative type pump means" as used herein shall be taken to have the meaning given in the preceding sentence.
Regenerative type pumps offer significant advantages compared with positive displacement pumps such as gear pumps. For example, regenerative pumps are inherently simpler and more compact in construction with a lower number of components that allow a reliable, lighter pump to be produced which, because of normal impeller/housing clearances, can tolerate liquids containing certain levels of particulate contaminants.
Another feature of regenerative type pumps is their ability to handle liquid/gas mixtures and to be self-priming if the pump outlet is located towards an inner region of the impeller. Liquid then collects towards the outer region of the flow channel and forms a "liquid ring" which pumps gas displaced towards the inner region because of its lower density. This characteristic is made use of in the invention by connecting an air bleed to the inner region of the second pump means to remove air separately from the lubricating oil output of the pump means to the reservoir.
It will be appreciated that a lubrication system according to the invention can be made in a more compact and lighter form than the known aerospace lubrication systems, by virtue of the fact that it involves combining two pump means on a common drive shaft and avoiding the need for separate driven air filter bodies and pressure relief valves.
The first and second regenerative type pump means may be formed on differe
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Redmond Frederick D.
Whitby Alan D.
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