GROOVED ROTOR FOR AN INTERNAL GEAR PUMP Background of the Invention This invention relates to improvements in the lubrication of internal surfaces for internal gear pumps. More particularly, this invention relates to an improvement in the design of the internal rotor of a gear pump such that the lubrication between the interface of the free secondary gear and the drive pinion is greatly improved. In a rotary internal gear pump, the secondary gear rotates on a stationary pin. The secondary gear is contained within the inner diameter of the rotor, the rear wall of the rotor and the front of the cover. The vast majority of applications can cause the secondary gear to rotate in the stationary transmission sprocket without problem since the fluid being pumped provides sufficient lubrication. However, since the lubricating properties of the fluid are reduced and / or operating pressures are increased, it has become a need for additional design features to assist in bringing the fluid to the interface of the inside diameter of the secondary gear and the outer diameter of the transmission sprocket. Previous designs have achieved this by drilling one or more holes through the root of the secondary gear or by adding a slot in the front of the cover from the pressure side of the pump. A need has arisen for an improved design for an internal gear pump. The present invention describes an improved design for a rotor of an internal gear pump that greatly improves the flow of fluid between the interface of the secondary gear and the transmission pinion, to provide lubrication. COMPENDIUM OF THE INVENTION The described slotted rotor efficiently improves fluid flow to the interface between the secondary gear and the transmission pinion of a typical internal gear pump. In case the lubricating properties of the fluid are reduced and / or the operating pressures of the pump are increased, the improved rotor design will increase the lubrication of the internal rotating parts, thus decreasing the friction between the parts and extending the life Total productive usefulness of the pump. In a preferred embodiment, a radially extending groove is added to the inner face of the rotor. The groove extends radially between the outer diameter of the rotor and the center of the rotor. The slot provides a communication channel between a fluid reservoir, in communication with the outer circumference of the rotor and the interface between the secondary gear and the transmission pinion. Pressurized fluid is forced to pass radially inward over the slot to the secondary pin / gear interface. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of an internal gear pump including the radial slotted rotor; Figure 2 is a cross-sectional view of the radial slotted rotor; Figure 3 is a sectional view of a radial slotted rotor, which is taken on the sectional line 3-3 of Figure 2; and Figure 4 is a sectional view of the radial slotted rotor, which is taken on the sectional line 3-3 of Figure 3. DETAILED DESCRIPTION OF THE PREFERRED MODALITY The present invention is directed to a rotor for an internal gear pump, which it is adapted to provide communication channels that allow fluid flow from the outer circumference of the rotor to its hollow interior. The rotor of the present invention is illustrated and described in the operating environment of an internal gear pump as described herein but is considered to have wide applications above and beyond the description of this preferred embodiment. As illustrated in Figure 1, the internal gear pump of the preferred embodiment is generally designated 10, includes a housing member 12, a housing plug 14, a housing bushing 16, a secondary gear 18, a transmission pinion 20, a rotor 22 and a cover plate 24. The housing member 12 has a first end internally threaded 26 and a second end which is defined by the cover plate 24. A first chamber 30 is defined within the first end 26 of the housing member 12 and a second chamber 31 is defined through the remainder of the housing member 12. The rotor 22 is rotatably disposed within the second chamber 31 and adapted to rotate with respect to its central axis. The rotor 22 includes a cup-shaped portion 32, best seen in Figure 2, and a feed arrow 34. The housing bushing 16 is disposed within the second chamber 31 and is adjacent to the shaped portion. cup 32 of the rotor 22. The housing bushing 16 allows the inlet arrow 34 to extend through and support the arrow for rotation. Also disposed within the chamber 30 is a retaining ring 36 located adjacent the housing bushing 16. A third chamber 38 is defined within the retaining ring 36 for housing a resilient branch member shown in the form of a retaining spring 40. arranged inside the third chamber 38. Adjacent to the retaining ring is the housing plug 14. The housing plug 14 is externally threaded to be attached to the first internally threaded end 26 of the housing member 12 and is widened to produce a fourth chamber 42 A seal member 44 is disposed within the fourth chamber 42, such that the retaining spring 40 is compressed between the retaining ring 36 and the seal member 44. The retaining spring 40 is adapted to displace the member. of seal 44 for coupling the housing plug 14, effecting a frontal compression of seal member 44 and preventing fluid leakage under pressure on the housing seal-plug interface and in the chamber 30. A second seal member 46 illustrated as an O-ring, is integrally disposed in a groove formed in the housing plug 14. The cup-shaped portion 32 of the rotor 22, has an outer diameter slightly smaller than the inner diameter of the second chamber 31 and an inner diameter greater than the outer diameter of the secondary gear 18, disposed within the portion 32 when the pump is assembled. The rotor 22 is adapted to couple the secondary gear 18 to effect its rotary movement. The secondary gear 18 defining a through opening 48 is adapted to rotate relative to the transmission sprocket 20. The transmission sprocket 20 is fixed against rotation and extends outward from the inner surface of the cover plate 24 within the opening 48. and toward the outer surface 50 of the cup-shaped chamber 32. The diameter of the opening 48 is slightly larger than the diameter of the transmission sprocket 20, to allow fluid flow over the interface between the outer diameter of the transmission sprocket and the inner diameter of the secondary gear. The cover plate 24 is secured to the second end of the housing member by cover bolts 52. The interior surface 50 of the cup-shaped member 32 is in a plane substantially perpendicular to the central axis of the rotor 22. A groove or channel communication 54 is defined • on the inner surface 50 of the rotor 22 and extends radially between approximately the central axis of the rotor 22 and the outer diameter of the cup-shaped portion 32 of the rotor 22. The communications channel 54 is adapted to communicate fluid under pressure from a fluid collector 56 into the cup-shaped portion 32. The introduction of fluid into the cup-shaped portion 32 allows lubrication of the interface between the secondary gear 18 and the transmission pinion. , and the secondary gear 18 and the rotor 22. Fluid is made to circulate from the collector 56., radially inward on the channel 54 when the fluid in the manifold 56 is pressurized during operation of the pump. When the pressurized fluid exerts a force greater than the centrifugal force caused by the rotation of the rotor, the fluid will circulate radially inwardly through the channel 54, until it reaches the passage defining the interface between the outer diameter of the transmission sprocket. and the inside diameter of the opening 48. The pressurized fluid then circulates over this passage providing lubrication on this passage, thereby reducing friction. Various features of the invention have been shown and described particularly in connection with the illustrated embodiment of the invention. However, it will be understood that these particular structures simply illustrate and that the invention will be given its fullest interpretation within the terms of the appended claims.