Housingless positive displacement pump assembly

1. A housingless positive displacement pump assembly comprising one or more vane or gerotor type housingless positive displacement pump units, the one or more pump units each comprising pump unit components, an exterior mounting flange exterior of one end of the pump assembly, and at least one retaining rod extending through axially aligned holes in the exterior mounting flange and the pump unit components to hold the pump unit components in stacked relation to one another and connect the pump assembly to the exterior mounting flange via a connection between an end of the retaining rod and the exterior mounting flange, wherein the at least one retaining rod comprises a single retaining rod that holds the pump unit components of a plurality of the pump units in stacked relation to one another and connects all of the pump units to the exterior mounting flange via the connection between the end of the single retaining rod and the exterior mounting flange.

2. The pump assembly of claim 1 wherein the one or more pump units are retained on the at least one retaining rod by retaining clips or pins on the ends of the at least one retaining rod.

3. The pump assembly of claim 1 wherein the pump units comprise one or more lube pump units or scavenge pump units.

4. The pump assembly of claim 1 installed in a bore in an application component housing with the exterior mounting flange attached to an exterior surface of the housing, the housing having respective passages communicating with inlet and discharge ports of the one or more pump units for pumping fluids through the passages.

5. The pump assembly of claim 4 wherein the application component is a gearbox, generator or engine or other application containing a fluid system.

6. The pump assembly of claim 4 wherein the bore is sized for close sliding receipt of the pump assembly and attachment of the exterior mounting flange to the exterior surface of the housing, the housing having inlet and discharge passages that communicate with the respective inlet and discharge ports of the one or more pump units.

7. The pump assembly of claim 6 wherein clearances are provided in the bore between the respective inlet and discharge ports of the one or more pump units and the inlet and discharge passages in the housing.

8. The pump assembly of claim 6 wherein the one or more of the pump units are retained on the at least one retaining rod by retaining clips or pins on the ends of the at least one retaining rod.

9. The pump assembly of claim 6 wherein the at least one retaining rod is spring loaded to provide a preload force on the pump unit components.

10. The pump assembly of claim 6 further comprising stack springs between the exterior mounting flange and the one end of the pump assembly that are compressed to a controlled height during insertion of the pump assembly into the bore and attachment of the exterior mounting flange to the exterior surface of the housing to provide a preload force on the pump unit components to maintain a fluid seal therebetween.

11. The pump assembly of claim 1 wherein an additional retaining rod holds the pump unit components of an additional pump unit in stacked relation and connects the additional pump unit to the one pump unit.

12. The pump assembly of claim 1 mounted in a bore in a housing of an application component or system for moving fluid through the application component or system, the bore in the housing of the application component or system being sized for close sliding receipt of the pump assembly and attachment of the exterior mounting flange to an exterior surface of the housing, the housing having inlet and discharge passages that communicate with respective inlet and discharge ports of the one or more pump units.

13. The pump assembly of claim 12 wherein clearances are provided in the bore between the respective inlet and discharge ports of the one or more pump units and the inlet and discharge passages in the housing.

14. The pump assembly of claim 12 wherein one or more of the pump units are retained on the one or more retaining rods by retaining clips or pins on the ends of the one or more retaining rods.

15. The pump assembly of claim 12 wherein at least one of the retaining rods is spring loaded to provide a preload force on the pump unit components.

16. The pump assembly of claim 12 further comprising stack springs between the exterior mounting flange and the one end of the pump assembly that are compressed to a controlled height during insertion of the pump assembly into the bore and attachment of the exterior mounting flange to the exterior surface of the housing to provide a preload force on the pump unit components to maintain a fluid seal therebetween.

17. The pump assembly of claim 1 wherein the exterior mounting flange comprises means for attaching the housingless positive displacement pump assembly to an exterior surface of an application component housing upon insertion of the housingless positive displacement pump assembly in a bore in the application component housing.

18. The pump assembly of claim 1 wherein an additional retaining rod holds the pump unit components of a plurality of additional pump units in stacked relation and connects the plurality of additional pump units to the one pump unit.

19. A housingless positive displacement pump assembly comprising one or more vane or gerotor type housingless positive displacement pump units, the one or more pump units each comprising pump unit components, an exterior mounting flange exterior of one end of the pump assembly, at least one retaining rod extending through axially aligned holes in the exterior mounting flange and the pump unit components to hold the pump unit components in stacked relation to one another and connect the pump assembly to the exterior mounting flange via a connection between an end of the retaining rod and the exterior mounting flange, and spring means for spring loading the at least one retaining rod to provide a preload force on the pump unit components to maintain a controlled fit of the pump assembly prior to installation in a bore in an application component housing.