Axle assembly having a lubricant reservoir module

1. An axle assembly comprising:

a differential;

a housing having a sump portion disposed proximate the differential and an arm portion that includes an end flange;

a reservoir module that is disposed in the arm portion between the differential and the end flange and configured to hold a volume of a lubricant, the reservoir module having a tube portion that is completely spaced apart from the housing;

an axle that is disposed in the arm portion such that the axle extends through and is spaced apart from the tube portion; and

a lubricant conduit that is disposed in the housing, wherein the lubricant conduit receives lubricant that splashes off the differential and provides the lubricant to the reservoir module;

wherein the lubricant conduit and reservoir module are disposed above the sump portion.

2. The axle assembly of claim 1 wherein the axle and the tube portion are coaxially disposed.

3. The axle assembly of claim 1 wherein the reservoir module has an inlet for providing the lubricant to the reservoir module.

4. The axle assembly of claim 3 wherein the reservoir module has an end plate and the inlet is provided with the end plate.

5. The axle assembly of claim 3 wherein the lubricant conduit provides lubricant to the inlet.

6. An axle assembly comprising:

a housing having an arm portion;

a reservoir module that is disposed in the arm portion and configured to hold a volume of a lubricant, the reservoir module having a tube portion that is completely spaced apart from the housing; and

an axle that is disposed in the arm portion such that the axle extends through and is spaced apart from the tube portion, wherein the tube portion is configured to flex with respect to the axle.

7. An axle assembly comprising:

a housing having an arm portion and a sump portion;

a reservoir module that is disposed in the arm portion, the reservoir module including a first end plate, a second end plate, and a tube portion that extends from the first end plate to the second end plate;

an axle that is disposed in the arm portion such that the axle extends through and is spaced apart from the tube portion; and

a differential that is configured to rotate the axle and that is disposed in the housing proximate the sump portion, wherein the first end plate faces toward the differential and includes a first outlet for providing a lubricant to the sump portion.

8. The axle assembly of claim 7 wherein the axle assembly further comprises a lubricant conduit that is disposed in the housing for providing the lubricant to an inlet of the reservoir module.

9. The axle assembly of claim 7 wherein the second end plate includes a second outlet.

10. The axle assembly of claim 7 wherein the first end plate, second end plate, and tube portion at least partially define a reservoir cavity that stores the lubricant.

11. The axle assembly of claim 10 wherein the first end plate includes an inlet for providing the lubricant to the reservoir cavity.

12. An axle assembly comprising:

a housing having an arm portion;

a reservoir module that is disposed in the arm portion, the reservoir module including a first end plate, a second end plate, a tube portion that extends from the first end plate to the second end plate, and a set of side plates, wherein each member of the set of side plates extends from the first end plate to the second end plate and is spaced apart from the tube portion; and

an axle that is disposed in the arm portion such that the axle extends through and is spaced apart from the tube portion;

wherein the first end plate, second end plate, and tube portion at least partially define a reservoir cavity that stores a lubricant.

13. The axle assembly of claim 12 wherein each member of the set of side plates engages at least one other member of the set of side plates.

14. The axle assembly of claim 12 wherein a member of the set of side plates includes an inlet.

15. An axle assembly comprising:

a housing having an arm portion;

a reservoir module that is disposed in the arm portion, the reservoir module including a first end plate, a second end plate, and a tube portion that extends from the first end plate to the second end plate;

a seal that is disposed between and engages the first end plate and the housing; and

an axle that is disposed in the arm portion such that the axle extends through and is spaced apart from the tube portion.

16. The axle assembly of claim 15 wherein the first end plate includes a first outlet.

17. The axle assembly of claim 16 wherein the first outlet is disposed below the axle and the tube portion.

18. An axle assembly comprising:

a housing having an arm portion;

a differential that is disposed in the housing and spaced apart from the arm portion;

an axle that is disposed in the arm portion and configured to be rotated by the differential; and

a reservoir module that is disposed in the arm portion and that at least partially defines a reservoir cavity that is configured to receive a lubricant, the reservoir module including:

a first end plate having an outlet,

a second end plate that is spaced apart from the first end plate,

a tube portion that extends from the first end plate to the second end plate, and

a valve for controlling flow of the lubricant through the outlet;

wherein the axle is spaced apart from the reservoir module and extends through the tube portion.

19. The axle assembly of claim 18 further comprising a volume sensor disposed in the reservoir module for providing a signal indicative of a volume of lubricant in the reservoir cavity, wherein the valve is opened when the volume of lubricant exceeds a threshold volume value.

20. The axle assembly of claim 18 further comprising a differential temperature sensor that detects a temperature proximate the differential, wherein the valve is opened when the temperature exceeds a threshold differential temperature value.