Fluid energy transfer device with improved bearing assemblies
A trochoidal gear pump or engine uses a coaxial hub with an outer and/or inner rotor and an associated rolling element bearing assembly that uses pre-loaded bearings to precisely set the rotational axis and/or the axial position of the rotor with which it is associated. This allows the fixed-gap clearance between the rotor surfaces and the housing or other rotor surfaces to be set at a distance that minimizes operating fluid shear forces and/or by-pass leakage and eliminates gear tooth wear thus preserving effective chamber to chamber sealing. The device is useful in handling gaseous and two-phase fluids in expansion/contracting fluid engines/compressors and can incorporate an output shaft for an integrated condensate pump for use with Rankine cycles. A vent from the housing cavity to a lower pressure input or output port regulates built-up fluid pressure in the housing, thereby optimizing the efficiency of the device by controlling bypass leakage.
1. A rotary chambered fluid energy-transfer device comprising:
(a) a housing comprising:
(1) a central portion having a central portion bore formed therein; and
(2) an end plate having an inlet passage and an outlet passage;
(b) an outer rotor rotatable in the central portion bore, the outer rotor comprising:
(1) a female gear profile formed in a radial portion;
(2) a first end covering the female gear profile;
(3) a second end skirting the female gear profile; and
(4) an outer rotor hub extending from the first end and mounted in the housing with a first bearing assembly comprising a rolling element bearing; and
(c) an inner rotor with a male gear profile in operative engagement with the outer rotor and having an inner rotor bore formed therein, the inner rotor mounted in the housing with a second bearing assembly comprising a first rolling element bearing and a second rolling element bearing mounted in a pre-loaded configuration with each other in the inner rotor bore by attachment means, wherein the first bearing assembly and the second bearing assembly:
1) set at least one of:
a) a rotational axis of the inner rotor;
b) a rotational axis of the outer rotor;
c) an axial position of the inner rotor; and
d) an axial position of the outer rotor; and
2) maintain a fixed-gap clearance of at least one of the inner rotor and the outer rotor with at least one surface of:
a) the housing; and
b) the other rotor.
2. The fluid energy-transfer device of claim 1 , wherein the fixed-gap clearance is a distance greater than a fluid boundary layer of an operating fluid used in the fluid energy-transfer device.
3. The fluid energy-transfer device of claim 1 , wherein the fixed-gap clearance is a substantially optimal distance as a function of bypass leakage and operating fluid shear forces.
4. The fluid energy-transfer device of claim 1 , wherein the fluid energy-transfer device is adapted for use as a prime mover.
5. The fluid energy-transfer device of claim 4 , wherein a pressurized operating fluid is used in the fluid energy-transfer device to provide a motive force.
6. The fluid energy-transfer device of claim 5 , wherein the inlet passage and the outlet passage of the end plate are configured for optimum expansion of the pressurized fluid in the fluid energy-transfer device.
7. The fluid energy-transfer device of claim 5 , wherein the pressurized fluid is in both a gaseous state and a liquid state.
8. The fluid energy-transfer device of claim 5 , wherein the pressurized fluid is in a gaseous state.
9. The fluid energy-transfer device of claim 4 , further comprising an integrated condensate pump driven from an output shaft of the fluid energy-transfer device.
10. The fluid energy-transfer device of claim 1 , wherein the fluid energy-transfer device is hermetically sealed.
11. The fluid energy-transfer device of claim 1 , wherein the fluid energy-transfer device is magnetically coupled with an external rotational shaft.
12. The fluid energy-transfer device of claim 1 , further comprising a conduit for venting operating fluid from an internal housing cavity.
13. The fluid energy-transfer device of claim 12 , wherein the operating fluid is vented to said outlet passage.
14. The fluid energy-transfer device of claim 12 , with the conduit further comprises a pressure regulating valve.
15. The fluid energy-transfer device of claim 1 , wherein the fluid energy-transfer device is adapted for use as a compressor.
16. The fluid energy-transfer device of claim 15 , wherein the inlet passage and the outlet passage of the end plate are configured for optimum compression of the fluid.
17. The fluid energy-transfer device of claim 1 , wherein the second bearing assembly is mounted on a housing hub of the housing.
18. The fluid energy-transfer device of claim 17 , wherein the housing hub is integral with the end plate.
19. The fluid energy-transfer device of claim 18 , further comprising an end cap attached to the housing hub with the attachment means to preload the second bearing assembly.
20. The fluid energy-transfer device of claim 17 , wherein the housing hub is attached to the end plate with the attachment means.
21. The fluid energy-transfer device of claim 20 , wherein the housing hub comprises an end flange to preload the second bearing assembly.
22. The fluid energy-transfer device of claim 1 , wherein the first bearing assembly further comprises a second rolling element bearing mounted in a pre-loaded configuration.