Patent Application
20230235737
The present disclosure relates to gerotor pumps and, in particular, to a stacked gerotor pump for pump pressure pulsation reduction.
A generated rotor or “gerotor” is a positive displacement pump and includes an inner rotor and an outer rotor. The inner rotor has n teeth, while the outer rotor has n+1 teeth sockets (with n defined as a natural number greater than or equal to 2). An axis of the inner rotor is offset from the axis of the outer rotor and both rotors rotate on their respective axes. The geometry of the two rotors partitions the volume between them into n different dynamically-changing volumes. During the assembly's rotation cycle, each of these volumes changes continuously, so any given volume first increases, and then decreases. An increase creates a vacuum. This vacuum creates suction, and hence, this part of the cycle is where the inlet is located. As a volume decreases, compression occurs whereby fluids can be pumped, or, if they are gaseous fluids, compressed.
According to an aspect of the disclosure, a stacked gerotor pump is provided. The stacked gerotor pump includes a first gerotor pump defining a first inlet section and a first outlet section, a second gerotor pump defining a second inlet section and a second outlet section and a plate. The plate is interposed between the first and second gerotor pumps and defines upstream cavities respectively communicative with the first and second inlet sections, downstream cavities respectively communicative with the first and second outlet sections and a pre-pressurization hole by which the second outlet section is communicative with the first inlet section.
In accordance with additional or alternative embodiments, the first gerotor pump compresses fluid in the first inlet section and discharges compressed fluid from the first outlet section and the second gerotor pump compresses fluid in the second inlet section and discharges compressed fluid from the second outlet section.
In accordance with additional or alternative embodiments, the compressed fluid of the second outlet section is communicated to the first inlet section via the pre-pressurization hole.
In accordance with additional or alternative embodiments, the second gerotor pump is at least slightly off-phase from the first gerotor pump.
In accordance with additional or alternative embodiments, the first and second gerotor pumps each include an inner rotor having an inner rotor axis and n teeth and being rotatable on the inner rotor axis, an outer rotor having an outer rotor axis, which is offset from the inner rotor axis, and n+1 teeth sockets and being rotatable on the outer rotor axis and an outer ring that surrounds the inner rotor and the outer rotor.
In accordance with additional or alternative embodiments, n is defined as a natural number greater than or equal to 2.
In accordance with additional or alternative embodiments, n is six.
In accordance with additional or alternative embodiments, the plate includes a first baffle separating the upstream cavities and a second baffle separating the downstream cavities.
In accordance with additional or alternative embodiments, each opposed circumferential face of each of the upstream cavities and each of the downstream cavities includes an inboard inward curvature and an outboard outward curvature.
According to an aspect of the disclosure, a stacked gerotor pump is provided and includes multiple gerotor assemblies and each of the multiple gerotor assemblies includes a first gerotor pump defining a first inlet section and a first outlet section, a second gerotor pump defining a second inlet section and a second outlet section and a plate interposed between the first and second gerotor pumps and defining upstream cavities respectively communicative with the first and second inlet sections, downstream cavities respectively communicative with the first and second outlet sections and a pre-pressurization hole by which the second outlet section is communicative with the first inlet section.
In accordance with additional or alternative embodiments, the first gerotor pump compresses fluid in the first inlet section and discharges compressed fluid from the first outlet section and the second gerotor pump compresses fluid in the second inlet section and discharges compressed fluid from the second outlet section.
In accordance with additional or alternative embodiments, the compressed fluid of the second outlet section is communicated to the first inlet section via the pre-pressurization hole.
In accordance with additional or alternative embodiments, the second gerotor pump is at least slightly off-phase from the first gerotor pump.
In accordance with additional or alternative embodiments, the first and second gerotor pumps each includes an inner rotor having an inner rotor axis and n teeth and being rotatable on the inner rotor axis, an outer rotor having an outer rotor axis, which is offset from the inner rotor axis, and n+1 teeth sockets and being rotatable on the outer rotor axis and an outer ring that surrounds the inner rotor and the outer rotor.
In accordance with additional or alternative embodiments, n is defined as a natural number greater than or equal to 2.
In accordance with additional or alternative embodiments, n is six.
In accordance with additional or alternative embodiments, the plate includes a first baffle separating the upstream cavities and a second baffle separating the downstream cavities.
In accordance with additional or alternative embodiments, each opposed circumferential face of each of the upstream cavities and each of the downstream cavities includes an inboard inward curvature and an outboard outward curvature.
In accordance with additional or alternative embodiments, the stacked gerotor pump further includes first and second end gerotor assemblies, each of the first and second end gerotor assemblies including a gerotor pump defining an inlet section and an outlet section and an end plate adjacent to the gerotor pump and defining an upstream cavity communicative with the inlet section and a downstream cavity communicative with the outlet section.
According to an aspect of the disclosure, a stacked gerotor pump is provided and includes multiple gerotor assemblies and end plates. Each of the multiple gerotor assemblies includes a first gerotor pump defining a first inlet section and a first outlet section, a second gerotor pump defining a second inlet section and a second outlet section and a plate. The plate is interposed between the first and second gerotor pumps and defines upstream cavities respectively communicative with the first and second inlet sections, downstream cavities respectively communicative with the first and second outlet sections and a pre-pressurization hole by which the second outlet section is communicative with the first inlet section. The end plates are adjacent to exterior ones of the first and second gerotor pumps and respectively define an upstream cavity communicative with the corresponding first or second inlet section and a downstream cavity communicative with the corresponding first or second outlet section.
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed technical concept. For a better understanding of the disclosure with the advantages and the features, refer to the description and to the drawings.
For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts:
Gerotors tend to cause discharge pressure ripples due to high air content in the fluid being pumped. More particularly, in a gerotor with an inner rotor and an outer rotor, the inner rotor is connected to an input shaft that spins and exerts a load on the outer rotor which also spins. As the gerotor thus comes into and out of its mesh condition, the gerotor discharges fluid discontinuously. The magnitude of the pressure signal's peak and the valley is the pressure ripple. Pre-pressurization has been proposed to reduce such pressure ripples in applications of gerotors.
Gerotors are commonly used as lube and scavenge pumps in aerospace applications. In these or other cases, gerotors tend to suffer from pressure ripple issues.
As will be described below, a stacked gerotor pump is provided and is formed to define pre-pressurization holes to reduce pressure pulsations.
With reference to
Upstream cavity 1131 is fluidly communicative with the first inlet section 1111 and upstream cavity 1132 is fluidly communicative with the second inlet section 1121. The first baffle 1136 isolates the upstream cavity 1131 and the first inlet section 1111 from the upstream cavity 1132 and the second inlet section 1121. Downstream cavity 1133 is fluidly communicative with the first outlet section 1112 and downstream cavity 1134 is fluidly communicative with the second outlet section 1122. The second baffle 1137 isolates the downstream cavity 1133 and the first outlet section 1112 from the downstream cavity 1134 and the second outlet section 1122. The pre-pressurization hole 1135 allows the second outlet section 1122 to be fluidly communicative with the first inlet section 1111. As such, the compressed fluid of the second outlet section 1122 is communicated to the first inlet section 1111 via the pre-pressurization hole 1135.
With the compressed fluid of the second outlet section 1122 being communicated to the first inlet section 1111 via the pre-pressurization hole 1135, a pressure of the fluid being discharged from the second outlet section 1122 by way of the downstream cavity 1134 can be reduced. This in turn reduces a magnitude of the pressure ripple.
Due to the reduced magnitude of the pressure ripple, downstream components that are receptive of pressurized fluids from the stacked gerotor pump 101 can be re-sized accordingly. That is, in a conventional lube and scavenge pump system in which pressure ripple magnitudes are high, downstream components need to be sufficiently large to withstand and absorb the effects of the high-magnitude pressure ripples. By contrast, in a lube and scavenge pump system using the stacked gerotor pump 101, pressure ripple magnitudes are reduced and downstream components can be downsized accordingly.
In accordance with embodiments, the downstream components can be any components requiring lubrication. These can include, but are not limited to, gears, motors/generators and clutches/starters.
With reference to
With reference back to
With continued reference to
Technical effects and benefits of the present disclosure are the provision of a gerotor pump that exhibits reduced pressure pulsations in a lubrication system that results in longer system component life, reduced cavitation damage and improved system performance.
The corresponding structures, materials, acts, and equivalents of all means or step-plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the technical concepts in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.
While the preferred embodiments to the disclosure have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the disclosure first described.
