Oil pump and gears

Abstract

An oil pump for an internal combustion engine includes a pump body with a first gear chamber and a second gear chamber, and a cover mounting to the pump body. The pump also has a check valve and a pressure relief valve in fluid communication with the gear chambers. The oil pump has a supply set of intermeshing involute spur gears in the first gear chamber with nine involute teeth. A return set of intermeshing involute spur gears with the same gear profile as the supply gears is housed in the second gear chamber. Both sets of gears are driven by a common drive shaft so that the pump may be retrofitted to existing engines. The profile of the gears provides for improved pump volume without increasing angular velocity or gear diameter over gears of the prior art. The return gears are deeper than the supply gears to provide an improved supply to return flow ratio.

1. An internal combustion engine oil pump, comprising:
 a pump body, including a first gear chamber and a second gear chamber; 
 a cover mounted to the pump body; 
 a drive shaft extending into the first gear chamber and the second gear chamber; 
 a first set of intermeshing involute spur gears in the first gear chamber, wherein each of the first set of gears has nine or fewer teeth, wherein each tooth has an involute profile;, and wherein one of the first set of gears is driven by the drive shaft; and 
 a second set of intermeshing involute spur gears in the second gear chamber, wherein one of the second set of gears is driven by the drive shaft; and, 
 wherein the a ratio of the a depth of the first set of gears to the a depth of the second set of gears is about 11/16; 
 wherein at least one of the gears in the first and second sets has an orifice for receiving the drive shaft; and 
 a snap ring retaining the drive shaft, the snap ring being recessed in the orifice to eliminate leakage around the drive shaft. 
 
     
     
       2. An oil pump according to  claim 1 , further comprising a check valve in fluid communication with one of the first and second gear chambers. 
     
     
       3. An oil pump according to  claim 1 , further comprising a pressure relief valve in fluid communication with the one of the first and second gear chambers. 
     
     
       4. An oil pump according to  claim 1 , wherein each of the second set of gears has nine or fewer teeth, and wherein each tooth has an involute profile. 
     
     
       5. An oil pump according to  claim 1 , wherein the a diametral pitch of the first set of gears is 12. 
     
     
       6. An oil pump according to  claim 1 , wherein the a pressure angle of the first set of gears is about 20 degrees. 
     
     
       7. A method of increasing oil flow in an internal combustion engine, comprising:
 providing the internal combustion engine, the engine having a first oil pump, the first oil pump having a first body, a first cover, a first set of intermeshing supply gears and a first set of intermeshing return gears driven off a common drift drive shaft, the method comprising the steps of:; 
 replacing the first set of supply gears with oil pump with a second oil pump fitting into a same dimensional space but that provides increased oil flow, the second oil pump including a second body, a second set of supply spur gears and a second set of return gears, wherein each of the second set of supply gears has nine involute teeth;, and 
 replacing the first set of return gears with a second set of return spur gears, wherein each of the second set of return gears has nine involute teeth;, 
 wherein a distance between the axes of the second set of supply gears is less than the a distance between the axes of the first set of supply gears, and wherein a distance between the axes of the second set of return gears is less than the a distance between the axes of the first set of return gears; 
 the first and second bodies each including an identical pattern of mounting apertures for attachment to the engine and having identical bore locations for receiving the drive shaft. 
 
     
     
       8. A method according to  claim 7 , wherein the second set of return gears has a greater depth than the second set of supply gears. 
     
     
       9. A method according to  claim 8 , wherein the a ratio of the a depth of the second set of supply gears to the a depth of the second set of return gears is about 11/16. 
     
     
       10. An oil pump for an internal combustion engine, comprising:
 a pump body, including a first gear chamber and a second gear chamber; 
 a cover mounted to the pump body; 
 a check valve in fluid communication with one of the first and second gear chambers, the check valve being operably connected to the one chamber and configured to prevent oil from flowing through the one chamber when the engine is not running but configured to actuate and release oil to a crankcase passage when actuated with a predetermined oil pressure; 
 a pressure relief valve in fluid communication with the one of the first and second gear chambers, the pressure relief valve being operably connected to the one chamber and configured to uncover a lower end crankcase passageway at about 10 psi and to uncover an excess oil passageway at about 30 psi; 
 a drive shaft extending into the first gear chamber and the second gear chamber; 
 a first set of intermeshing involute spur gears in the first gear chamber, wherein each of the first set of gears has nine or fewer teeth, wherein each tooth has an involute profile;, and wherein one of the first set of gears is driven by the drive shaft; 
 a second set of intermeshing involute spur gears in the second gear chamber, wherein one of the second set of gears is driven by the drive shaft; and, 
 wherein the a ratio of the a depth of the first set of gears to the a depth of the second set of gears is about 11/16 such that a greater volume of oil is pumped for return than for supply, since the oil being pumped for return includes more air than the oil being pumped for supply. 
 
     
     
       11. An oil pump according to  claim 10 , wherein each of the second set of gears has nine or fewer teeth. 
     
     
       12. An oil pump according to  claim 11 , wherein the teeth comprise involute gear teeth. 
     
     
       13. An oil pump according to  claim 10 , wherein the diametral pitch of the first gears is 12. 
     
     
       14. An oil pump according to  claim 10 , wherein the pressure angle of the gears is about 20 degrees. 
     
     
       15. A retrofit engine oil pump designed to fit onto an internal combustion engine and to replace an existing oil pump of the internal combustion engine, the engine defining a pattern including mounting holes and a drive-shaft-receiving aperture, and the existing pump including a first body with first attachment holes matching the pattern, a first drive shaft aligned with the drive-shaft-receiving aperture, and existing sets of intermeshing gears having rotational centers defining a known distance, the retrofit engine oil pump comprising:
 a retrofit pump body including first and second gear chambers and also second attachment holes matching the pattern and also drive-shaft-supporting structure aligned with the drive-shaft-receiving aperture; such that the second pump is mountable in place of the existing oil pump;   a cover mounted to the retrofit pump body, the cover closing one side of the first gear chamber of the retrofit pump body;   the retrofit pump body being configured and adapted so that, when mounted, the engine closes a side of the second gear chamber of the retrofit pump body;   a retrofit drive shaft supported by the drive-shaft-supporting structure and extending into the first gear chamber and the second gear chamber;   a first set of intermeshing gears in the first gear chamber, wherein one of the first set of gears is driven by the retrofit drive shaft; and   a second set of intermeshing gears in the second gear chamber, wherein one of the second set of gears is driven by the retrofit drive shaft,   wherein a first distance between rotational centers of the first set of intermeshing gears in the first gear chamber equals a second distance between rotational centers of the second set of intermeshing gears in the second gear chamber, and   wherein the first distance and the second distance are less than the known distance between the rotational centers of corresponding gears in the existing oil pump.   
     
     
       16. An oil pump according to claim 15, wherein a ratio of a depth of the first set of gears to a depth of the second set of gears is about 11/16. 
     
     
       17. An oil pump according to claim 15, further comprising a check valve in fluid communication with one of the first and second gear chambers. 
     
     
       18. An oil pump according to claim 15, further comprising a pressure relief valve in fluid communication with the one of the first and second gear chambers. 
     
     
       19. An oil pump according to claim 15, wherein a diametral pitch of the first set of gears is 12. 
     
     
       20. An oil pump according to claim 1, wherein a pressure angle of the first set of gears is about 20 degrees. 
     
     
       21. An oil pump according to claim 15, wherein the first set of intermeshing gears comprise involute spur gears having nine or fewer teeth. 
     
     
       22. An oil pump according to claim 15, wherein the second set of intermeshing gears comprise involute spur gears having nine or fewer teeth. 
     
     
       23. An oil pump according to claim 15, wherein the retrofit oil pump comprises an external gear rotary oil pump. 
     
     
       24. An oil pump according to claim 15, wherein the first set of intermeshing gears and the second set of intermeshing gears have a pitch circle diameter of 0.811 inches. 
     
     
       25. A method of providing increased oil flow in an engine comprising steps of:
 providing a motorcycle engine including a first oil pump with a first pump body and first intermeshing supply gears with centers defining a first distance and first intermeshing return gears with centers also defining the first distance; the first pump body defining a first set of attachment orifices arranged in a first pattern for aligning with existing mounting structure on the engine for attachment;   constructing a second oil pump with a second pump body and second intermeshing supply gears with centers defining a second distance and second intermeshing return gears also with centers defining the second distance; the second distance being less than the first distance; the second pump body defining a second set of attachment orifices arranged in the first pattern for aligning with the existing mounting structure on the engine for attachment; the first intermeshing supply and return gears providing an increased rate of oil flow than the second intermeshing supply and return gears; the second pump body being configured to fit within a same space on the engine as the first pump body; and   replacing the first pump by detaching the first pump and then attaching the second pump, including using the existing mounting structure on the engine and including fitting into the same space on the engine.   
     
     
       26. The method defined in claim 25, wherein the step of constructing the second pump includes providing the second intermeshing supply and return gears with an involute spur tooth profile shaped to increase oil pump volume at a same rpm by at least 26%. 
     
     
       27. The method defined in claim 26, wherein the step of constructing the second pump includes providing the second intermeshing supply gears with an involute spur tooth profile to increase oil pump volume at a same rpm on a supply side by at least supply 38%. 
     
     
       28. The method defined in claim 26, wherein the step of constructing the second pump includes providing the second intermeshing return gears with an involute spur tooth profile and depth to increase oil pump volume at a same rpm on a return side by at least supply 61%. 
     
     
       29. The method defined in claim 25, wherein the step of constructing the second pump includes providing on the second pump body a relief valve opening and a pressure relief valve mounted to the relief valve opening, and opening the relief valve at an oil pressure of at least about 10 psi to provide oil to selected components of the engine. 
     
     
       30. The method defined in claim 25, including further opening the relief valve at an oil pressure of at least about 30 psi to flow excess oil through an excess oil passageway acting as pressure relief passage to prevent both over pressure and over oiling. 
     
     
       31. The method defined in claim 25, wherein the step of constructing includes forming a keyway channel in one of the gears that aligns with a base of a tooth in the one gear. 
     
     
       32. The method defined in claim 25, wherein the step of constructing includes forming a recess for a snap ring within a drive-shaft-receiving orifice in one of the gears, and including placing the snap ring within the one gear in the recess. 
     
     
       33. The oil pump according to claim 25, wherein the first set of intermeshing gears and the second set of intermeshing gears have a pitch circle diameter of 0.811 inches. 
     
     
       34. The oil pump according to claim 33, wherein a diametral pitch of the first set of gears is 12. 
     
     
       35. The oil pump according to claim 34, wherein a pressure angle of the first set of gears is about 20 degrees. 
     
     
       36. An apparatus comprising:
 a vehicle engine having limited space for pumping oil;   a first oil pump with a first pump body and first intermeshing supply and return gears with rotational centers defining a first distance; the first pump body defining first attachment orifices arranged in a first pattern for attaching to the engine in the limited space;   a second oil pump with a second pump body and second intermeshing supply and return gears with rotational centers defining a second distance less than the first distance; the second pump body defining a second set of attachment orifices arranged in the first pattern for attaching to the engine; the second intermeshing supply and return gears providing an increased oil flow of at least 26% over the first intermeshing supply and return gears; and   whereby the first pump can be replaced by detaching the first pump and then attaching the second pump without further modification or change of style of the vehicle engine.   
     
     
       37. The apparatus defined in claim 36, including a keyway in one of the gears in the second oil pump that aligns with a base of one tooth and that is adapted to matingly engage a drive shaft extending through the one gear. 
     
     
       38. The apparatus defined in claim 36, including a recess in one of the gears in the second oil pump and a snap ring in the recess within the one gear that retains a drive shaft and that limits leakage around the drive shaft. 
     
     
       39. A method of improving distribution and flow of oil in an internal combustion engine, comprising:
 providing a motorcycle engine including a pattern of existing oil-pump-mounting structure and confined space around the oil-pump-mounting structure;   removing a stock oil pump having a first pump body with first intermeshing gears; and   attaching a second oil pump to the existing oil-pump-mounting structure, the second oil pump including a second pump body of equal size to the first pump body, first and second gear chambers, intermeshing supply and return gears providing an increased oil flow but having rotational centers closer together than the first intermeshing gears; a check valve in fluid communication with one of the first and second gear chambers, the check valve being operably connected to the one chamber and configured to prevent oil from flowing through the one chamber when the engine is not running but configured to actuate and release oil to a crankcase passageway when actuated with a predetermined oil pressure, and a pressure relief valve in fluid communication with the one of the first and second gear chambers, the pressure relief valve being operably connected to the one chamber and configured to uncover a lower end crankcase passageway at less than 10 psi and to uncover an excess oil passageway at more than 30 psi.   
     
     
       40. The method defined in claim 39, including operating the motorcycle engine to cause oil pressure fluctuations of greater than 10 psi but less than 30 psi, and also to cause oil pressure fluctuations of greater than 30 psi. 
     
     
       41. The method defined in claim 7, including forming a keyway in one of the gears for engaging the drive shaft, including aligning the keyway with a base of one tooth. 
     
     
       42. The method defined in claim 7, including forming a recess in one of the gears for receiving a snap ring to retain the drive shaft and to prevent leakage around the drive shaft. 
     
     
       43. The oil pump defined in claim 15, including a keyway in one of the gears for engaging the drive shaft, the keyway being aligned with a base of one tooth of one of the gears. 
     
     
       44. The oil pump defined in claim 15, including a recess in one of the gears for receiving a snap ring to retain the drive shaft and to prevent leakage around the drive shaft.