Fluid delivery system with a shaft having a through-passage

1. A pump comprising:

a casing defining an interior volume, the casing including a first port in fluid communication with the interior volume, and a second port in fluid communication with the interior volume;

a first gear disposed within the interior volume, the first gear having a first gear body and a plurality of first gear teeth;

a second gear disposed within the interior volume, the second gear having a second gear body and a plurality of second gear teeth projecting radially outwardly from the second gear body, the second gear is disposed such that a first face of at least one tooth of the plurality of first gear teeth meshes with a second face of at least one tooth of the plurality of second gear teeth when the first gear is rotated;

a motor disposed in the interior volume, the motor to rotate the first gear about a first axial centerline of the first gear in a first direction to transfer a fluid from the first port to the second port along a first flow path, a meshing force from the first face to rotate the second gear about a second axial centerline of the second gear in a second direction to transfer the fluid from the first port to the second port along a second flow path; and

at least one flow-through shaft disposed in at least one of the motor, the first gear or the second gear, each of the at least one flow-through shaft having a through passage along an axial centerline of the respective flow-through shaft such that a first end of the through-passage is in fluid communication with a fluid chamber of a storage device and a second end of the through-passage, which is opposite the first end, is configured to be in fluid communication with the first port or the second port,

wherein each through-passage of the at least one flow-through shaft comprises a tapered portion extending from the first end of the through-passage and to a point part-way into the through-passage, and

wherein a diameter of the tapered portion at the first end of the through-passage is larger than a diameter of the tapered portion at the point part-way into the through passage.

2. The pump of claim 1 , wherein each through-passage of the at least one flow-through shaft comprises an expansion portion disposed next to the tapered portion extending toward the second end of the through-passage.

3. The pump of claim 2 , wherein a smallest diameter of the expansion portion is equal to or larger than a smallest diameter of the tapered portion.

4. The pump of claim 2 , wherein the tapered portion extends 5% to 50% of a length of the through-passage.

5. The pump of claim 2 , wherein a diameter of the expansion portion is equal to a largest diameter of the tapered portion.

6. The pump of claim 2 , wherein the casing comprises at least one fluid channel that extends through the casing, the at least one fluid channel corresponding in number to the at least one flow-through shaft,

wherein a first end of each of the at least one fluid channel is in fluid communication with the second end of each through-passage of the at least one flow-through shaft, and a second end of each of the at least one fluid channel is in fluid communication with the first port or the second port.

7. The pump of claim 6 , wherein a diameter of each of the at least one fluid channel is larger than a smallest diameter of the respective tapered portion of the at least one flow-through shaft.

8. The pump of claim 7 , wherein a ratio of the diameter of the fluid channel to the smallest diameter of the tapered portion ranges between 1.5 to 1.75.

9. The pump of claim 1 , wherein the at least one flow-through shaft includes a first flow-through shaft and a second flow-through shaft, and

wherein the first flow-through shaft is disposed in the motor and the second flow-through shaft is disposed in the second gear.

10. The pump of claim 1 , wherein the first gear body includes a cylindrical opening along the first axial centerline for accepting the motor,

wherein the motor is an outer-rotor motor and is disposed in the cylindrical opening, the motor comprising a rotor,

wherein the rotor is coupled to the first gear to rotate the first gear about the first axial centerline in the first direction, and

wherein the at least one flow-through shaft include a first flow-through shaft that is disposed in the motor.

11. The pump of claim 10 , wherein the first gear is disposed radially outward of the rotor and supported by the rotor.

12. The pump of claim 1 , wherein the at least one flow-through shaft includes a first flow-through shaft that is disposed in at least one of the motor or the first gear, the first flow-through shaft having a stationary portion and a rotating portion,

wherein the motor is an internal-rotor motor comprising a rotor coupled to the first flow-through shaft such that the rotating portion of the first flow-through shaft rotates with the rotor, and

wherein the rotating portion of the first flow-through shaft is coupled to the first gear to rotate the first gear about the first axial centerline in the first direction.

13. The pump of claim 1 , wherein the motor is disposed in an opening of the first gear.

14. The pump of claim 13 , wherein the at least one flow-through shaft includes a second flow-through shaft that is disposed in the second gear.

15. The pump of claim 1 , wherein the fluid is a hydraulic fluid.

16. The pump of claim 15 , wherein the pump operates in a range of 1 rpm to 5000 rpm.

17. The pump of claim 1 , wherein the fluid is water.

18. The pump of claim 17 , wherein the pump operates in range of 1 rpm to 5000 rpm.