In-situ serviceable gear pump
The present invention exhibits a set of improvements that increases the serviceability of the known internal gear pump employing a key and matching keyway engagement between the drive shaft and a star gear. A primary benefit is that all wetted components can be accessed by only removing the front cover assembly and do not require the internal gear pump be disconnected from its drive motor or piping. Furthermore, the mechanical seals are designed to be serviced from the front of the pump such that all wetted surfaces can be accessed, cleaned, serviced by removing the front cover assembly, with the pump installed in place. Additionally, a bearing unit supporting the drive shaft is similarly removable from the front of the pump.
1 . An internal gear pump comprising:
a pump housing having a cavity open to a front side and a back wall with a hole therethrough;
a drive shaft passed through the hole;
a star gear having star gear teeth, the star gear coupled to the drive shaft;
a ring gear having ring gear teeth circumferentially around an open center, the star gear disposed within the open center and a portion of the ring gear teeth are engaged with a portion of the star gear teeth;
a crescent shaped divider affixed to the back wall of the pump housing and disposed within the open center between another portion of the ring gear teeth and another portion of the star gear teeth;
a front cover assembly enclosing the cavity of the pump housing from the front side;
a bearing unit disposed in an annular space around the hole for the drive shaft, the bearing unit capable of sliding axially such that the bearing unit is removable from the drive shaft to the front side when the front cover assembly is removed after the star gear is removed; and
a compression spring disposed in the annular space behind the bearing unit forces the bearing unit against a rear surface of the star gear and compresses a rear sealing mechanism between the bearing unit and the rear surface of the star gear;
wherein the drive shaft is coupled to the star gear by a radial key and keyway capable of sliding axially between the drive shaft and the star gear such that the star gear is removable from the drive shaft to the front side when the front cover assembly is removed.
2 . The internal gear pump of claim 1 , wherein the ring gear is removable to the front side when the front cover assembly is removed after the star gear is removed.
3 . The internal gear pump of claim 1 , wherein the rear sealing mechanism comprises an o-ring within a circular groove of the bearing unit.
4 . The internal gear pump of claim 1 , wherein the front cover assembly is secured to the pump housing with a plurality of screws.
5 . The internal gear pump of claim 1 , wherein the front cover assembly comprises a window for viewing the cavity with the front cover assembly enclosing the cavity in operation.
6 . The internal gear pump of claim 1 , wherein the drive shaft and the star gear are coupled together as a single unit.
7 . A method of making an internal gear pump comprising the steps of:
providing a pump housing having a cavity open to a front side and a back wall with a hole therethrough;
providing a drive shaft passed through the hole;
providing a star gear having star gear teeth, the star gear coupled to the drive shaft;
providing a ring gear having ring gear teeth circumferentially around an open center, the star gear disposed within the open center and a portion of the ring gear teeth are engaged with a portion of the star gear teeth;
providing a crescent shaped divider affixed to the back wall of the pump housing and disposed within the open center between another portion of the ring gear teeth and another portion of the star gear teeth;
providing a front cover assembly enclosing the cavity of the pump housing from the front side; and
a bearing unit disposed in an annular space around the hole for the drive shaft, the bearing unit capable of sliding axially such that the bearing unit is removable from the drive shaft to the front side when the front cover assembly is removed after the star gear is removed;
wherein the drive shaft is coupled to the star gear by a radial key and keyway capable of sliding axially between the drive shaft and the star gear such that the star gear is removable from the drive shaft to the front side when the front cover assembly is removed; and
wherein a compression spring disposed in the annular space behind the bearing unit forces the bearing unit against a rear surface of the star gear and compresses a rear sealing mechanism between the bearing unit and the rear surface of the star gear.
8 . The method of claim 7 , wherein the ring gear is removable to the front side when the front cover assembly is removed after the star gear is removed.
9 . The method of claim 7 , wherein the rear sealing mechanism comprises an o-ring within a circular groove of the bearing unit.
10 . The method of claim 7 , wherein the front cover assembly is secured to the pump housing with a plurality of screws.
11 . The method of claim 7 , wherein the front cover assembly comprises a window for viewing the cavity with the front cover assembly enclosing the cavity in operation.
12 . The method of claim 7 , wherein the drive shaft and the star gear are coupled together as a single unit.