Patent Description:
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+<NUM> teeth sockets (with n defined as a natural number greater than or equal to <NUM>). 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. <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> all relate to pumps including multiple gerotor assemblies arranged along an axial direction, but not as such in a stacked manner.

According to an aspect of the disclosure, a stacked gerotor pump is provided as claimed in claim <NUM>. 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.

The first gerotor pump compresses fluid in the first inlet section and discharge compressed fluid from the first outlet section and the second gerotor pump compresses fluid in the second inlet section and discharge compressed fluid from the second outlet section.

The compressed fluid of the second outlet section is communicated to the first inlet section via the pre-pressurization hole.

The second gerotor pump may be at least slightly off-phase from the first gerotor pump.

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+<NUM> teeth sockets and being rotatable on the outer rotor axis and an outer ring that surrounds the inner rotor and the outer rotor.

n is defined as a natural number greater than or equal to <NUM>.

The plate may include a first baffle separating the upstream cavities and a second baffle separating the downstream cavities.

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 as claimed in claim <NUM>, 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.

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+<NUM> teeth sockets and being rotatable on the outer rotor axis and an outer ring that surrounds the inner rotor and the outer rotor.

Each opposed circumferential face of each of the upstream cavities and each of the downstream cavities may include an inboard inward curvature and an outboard outward curvature.

The stacked gerotor pump further may include 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 as claimed in claim <NUM> 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.

For a more complete understanding of this disclosure and the invention as defined by the appended claims, 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 <FIG> and <FIG>, a stacked gerotor pump <NUM> is provided and includes two or more gerotor assemblies <NUM>, a first end gerotor assembly <NUM> at a first end of the stack and a second end gerotor assembly <NUM> at a second end of the stack opposite the first end of the stack. Each of the multiple gerotor assemblies <NUM> includes a first gerotor pump <NUM>, a second gerotor pump <NUM> and a plate <NUM>. The first gerotor pump <NUM> is formed to define a first inlet section <NUM> (see <FIG>), in which fluid is compressed, and a first outlet section <NUM> (see <FIG>), from which compresses fluid is discharged. The first gerotor pump <NUM> can be operable in a first phase. The second gerotor pump <NUM> is formed to define a second inlet section <NUM> (see <FIG>), in which fluid is compressed, and a second outlet section <NUM> (see <FIG>), from which compressed fluid is discharged. The second gerotor pump <NUM> can be operable in a second phase. The second phase can be in-phase with the first phase, can be slightly off-phase from the first phase or can be substantially off-phase from the first phase. The plate <NUM> is formed to define upstream cavities <NUM> and <NUM>, downstream cavities <NUM> and <NUM> (hidden) and a pre-pressurization hole <NUM>. The plate <NUM> includes a first baffle <NUM>, which separates the upstream cavities <NUM> and <NUM> from one another, and a second baffle <NUM>, which separates the downstream cavities <NUM> and <NUM> from one another.

Upstream cavity <NUM> is fluidly communicative with the first inlet section <NUM> and upstream cavity <NUM> is fluidly communicative with the second inlet section <NUM>. The first baffle <NUM> isolates the upstream cavity <NUM> and the first inlet section <NUM> from the upstream cavity <NUM> and the second inlet section <NUM>. Downstream cavity <NUM> is fluidly communicative with the first outlet section <NUM> and downstream cavity <NUM> is fluidly communicative with the second outlet section <NUM>. The second baffle <NUM> isolates the downstream cavity <NUM> and the first outlet section <NUM> from the downstream cavity <NUM> and the second outlet section <NUM>. The pre-pressurization hole <NUM> allows the second outlet section <NUM> to be fluidly communicative with the first inlet section <NUM>. As such, the compressed fluid of the second outlet section <NUM> is communicated to the first inlet section <NUM> via the pre-pressurization hole <NUM>.

With the compressed fluid of the second outlet section <NUM> being communicated to the first inlet section <NUM> via the pre-pressurization hole <NUM>, a pressure of the fluid being discharged from the second outlet section <NUM> by way of the downstream cavity <NUM> 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 <NUM> 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 <NUM>, 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 <FIG>, the first and second gerotor pumps <NUM> and <NUM> can each include an inner rotor <NUM> having an inner rotor axis and n teeth <NUM> and being rotatable on the inner rotor axis, an outer rotor <NUM> having an outer rotor axis and an outer ring <NUM>. The outer rotor <NUM> is offset from the inner rotor axis and has n+<NUM> teeth sockets <NUM>. The inner rotor <NUM> is rotatable about the inner rotor axis within an aperture within the outer rotor <NUM> such that the teeth <NUM> of the inner rotor <NUM> engage sequentially with the n+<NUM> teeth sockets <NUM> of the outer rotor <NUM>. The aperture of the outer rotor <NUM> can be scalloped to form the n+<NUM> teeth sockets <NUM>. The outer rotor <NUM> is rotatable on the outer rotor axis. The outer ring <NUM> surrounds the inner rotor <NUM> and the outer rotor <NUM>. In accordance with embodiments, n can be defined as a natural number greater than or equal to <NUM> (e.g., six). With this construction, as shown in <FIG>, the interaction of the n teeth <NUM> of the inner rotor <NUM> and the n+<NUM> teeth sockets <NUM> of the outer rotor <NUM> forms an inlet (i.e., the first or second inlet section <NUM> or <NUM>) and an outlet (i.e., the first or second outlet section <NUM> or <NUM>).

With reference back to <FIG>, the upstream cavities <NUM> and <NUM> and the downstream cavities <NUM> and <NUM> generally taper outwardly with increasing radial distance from a central axis. In addition, as shown in <FIG>, each opposed circumferential face <NUM> of each of the upstream cavities <NUM> and <NUM> and each of the downstream cavities <NUM> and <NUM> includes an inboard inward curvature <NUM> and an outboard outward curvature <NUM>.

With continued reference to <FIG>, the first end gerotor assembly <NUM> and the second end gerotor assembly <NUM> each include a first or second gerotor pump <NUM> or <NUM> as described above and an end plate <NUM> adjacent to the first or second gerotor pump <NUM> or <NUM>. The end plate <NUM> defines an upstream cavity <NUM> or <NUM> that is fluidly communicative with the corresponding first or second inlet section <NUM> or <NUM> and a downstream cavity <NUM> or <NUM> that is fluidly communicative with the corresponding first or second outlet section <NUM> or <NUM> similarly as described above.

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.

Claim 1:
A stacked gerotor pump (<NUM>), comprising:
a first gerotor pump (<NUM>) defining a first inlet section (<NUM>) and a first outlet section (<NUM>);
a second gerotor pump (<NUM>) defining a second inlet section (<NUM>) and a second outlet section (<NUM>); and
a plate (<NUM>) interposed between the first and second gerotor pumps, characterised in that the plate defines upstream cavities (<NUM>, <NUM>) respectively communicative with the first and second inlet sections (<NUM>, <NUM>), downstream cavities (<NUM>, <NUM>) respectively communicative with the first and second outlet sections (<NUM>, <NUM>) and a pre-pressurization hole (<NUM>) by which the second outlet section is communicative with the first inlet section.