This disclosure relates to compact configurations for combining a pump stage with a motor.
Compact motor-driven pumps are commonly employed to deliver fuel, lubricants, hydraulic or other fluids in equipment, land and water vehicles and aircraft. The pumps and motors are commonly manufactured separately and then assembled into the same housing, which may also serve as a conduit for fluid being pumped. The fluid being pumped may circulate through the motor to lubricate and cool the motor and electronics associated with a brushless motor configuration.
Roller vane, gerotor and turbine pump stages are commonly employed in such assemblies, with the pump stage selected based on the characteristics of the fluid being pumped and the pressure and volume of fluid flow required by the system. In the case of roller vane and gerotor pump designs, the pump stage typically includes three components that define a pumping chamber. An inlet plate defines one or more arcuate inlet ports for fluid to enter the pumping chamber and defines one axial side of the pumping chamber. An outlet plate defines one or more arcuate outlet ports and defines the opposite axial side of the pumping chamber. A retainer ring is sandwiched between the inlet and outlet plates and defines the radial, inside surface of the pumping chamber. In roller vane and gerotor pumps, the inside surface of the pumping chamber is defined by a circle eccentric from the center (rotational) axis of the motor and pump. The position of the inlet and outlet ports, in combination with eccentrically rotating roller vane or gerotor pump components, result in differential pressures in the pump chamber that force fluid through the pump from the inlet to the outlet. Pumped fluid may be directed through the motor for the purpose of cooling and lubrication.
With respect to gerotor pumps in particular, the geometry and alignment of pump components is critical to smooth and reliable pump operation. One important relationship is the rotational axis of the inner gerotor and rotational axis of the motor shaft, which are preferably concentric (as close to the same axis as possible). Most gerotor pumps employ separately manufactured inlet and outlet plates axially spaced by the retainer ring. Separately manufactured parts must be tightly tolerance to prevent tolerance stack up issues that will interfere with proper gerotor pump operation. Further, the separate components must be carefully aligned during assembly to ensure a concentric relationship between the motor shaft, the inner gerotor and the eccentric path of the outer gerotor. Alignment is typically accomplished by pins or fasteners extending axially through the inlet plate, retainer ring, and outlet plate. Other unique assembly methods may be employed to ensure correct alignment of the several components. The inner gerotor may be centered on a bushing pin supported by one of the inlet or outlet plates. Alternatively, the inner gerotor may be supported by the motor shaft itself, depending upon the size of the motor shaft. Separately manufactured components with alignment structures may complicate manufacturing, assembly, and increase costs and have a potentially negative impact on reliability.
An integrated motor-driven pump is proposed that reduces the part count of the assembly and addresses several tolerance and alignment issues by combining the outlet plate and retainer ring of the pump into a single component. The integrated motor-driven pump may also include an axial bushing for support of the motor shaft and inner gerotor, ensuring concentric rotation of these components. Combining one of the inlet or outlet plates with the retainer ring and including a central bushing eliminates the need for alignment pins and complex assembly procedures. The disclosure also combines one of the motor end plates with the disclosed integrated pump inlet or outlet plate, retainer ring and central bushing, eliminating the need for a separate motor end plate and bushing to support the motor shaft.
The disclosed motor-driven pump preferably employs a brushless motor configuration and directs pumped fluid through the motor for cooling and lubrication. Pumped fluid may also be directed to cool the control electronics which drive the brushless motor, directly or indirectly. The motor end plate is formed as a single component with one of the pump inlet or outlet plates, and incorporates the retainer ring and a central bushing to support both the motor shaft and inner gerotor. The pump stage may include as few as three components; the inner gerotor, outer gerotor and one plate of the pump (typically the inlet plate, which may alternatively be referred to as the inlet manifold.
In one embodiment, a motor end plate is adapted to serve as the inlet or outlet plate of a pump secured to an axial end of the motor driving the pump.
In one embodiment, a motor end plate is integrated with an inlet or outlet plate of a pump, a guide ring of the pump and bushings to support the motor shaft and rotating pump parts.
Alternative embodiments of the disclosed integrated motor pump may incorporate one or more of the disclosed features and relationships included in the detailed description below.
A first embodiment of a gerotor pump 10 partially integrated with its drive motor 20 is illustrated in
The disclosed combined motor end plate/outlet manifold 22 is constructed of materials and surface properties compatible with its function as a working surface of a gerotor pump 10. The material must be resistant to wear and begin with a planar (flat) surface that will cooperate with adjacent surfaces of the gerotor set to define differential pressure zones within the pump 10. Suitable materials include steel or alloy that is cast or machined and finished to the correct dimensions. Powdered metallurgy may also be employed to form parts such as the combined motor end plate/outlet manifold/retainer ring component 150 of the embodiment shown in
It will be observed that, in the embodiment of
The embodiment of
Comparison of
The disclosed concept for integrating a compact pump with an electric motor is discussed in the context of a gerotor pump, but is not limited to only this pump configuration. Other compact pump configurations employ an eccentric surface to guide pump components or to direct fluid flow through the pump and may advantageously employ the disclosed concepts. Such pumps include, but are not limited to vane and roller vane pumps.
Number | Date | Country | |
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62182232 | Jun 2015 | US | |
62276272 | Jan 2016 | US |