Patent Application
20100014991
This invention relates to engine oil pump pressure regulation and particularly to variation of oil pump outlet pressure as a function of engine speed.
It is known in the art relating to engine oil pumps to vary the pump displacement as a function of pump outlet pressure in order to maintain a constant oil outlet pressure as the speed of the engine driving the pump is varied. This mode of control increases engine efficiency with a positive displacement pump by reducing the volume of oil pumped at higher engine speeds with a resultant saving of energy. However, with the varying demands being made to provide smaller but more powerful engines having increased fuel economy, consideration was given to modifying the pressure oil control system to allow some increase in controlled oil pressure as a function of increased engine speed. A simplified system for providing such an improvement was desired.
The present invention takes advantage of the energy present in air and other fluids that are placed in motion through their continuing presence near rotating components of an engine, such as the crankshaft, balance shafts, camshafts, transmission shafts and the like. For example, the rotation of a crankshaft in an engine crankcase creates a substantial amount of motion in the fluid and entrained oil droplets that are stirred up by the movement of the crank throws, connecting rods and counterweights through the oil containing fluid. The energy present in this moving fluid is utilized in the invention by convening the momentum of a captured portion of the moving fluid to a static pressure that is a function of the engine speed. This pressure may also be used in various ways to modify the control functions of other devices.
In a specific embodiment, the invention uses the static pressure in fluid as an actuating force in an oil pump displacement control. The static pressure is applied directly to a chamber within the pump to modify the pressure control based upon the oil pump outlet oil pressure, which reduces the pump displacement to maintain a pressure control function. The addition of the static pressure, collected from the momentum of fluid rotating with the outer surface of a crankshaft counterweight, modifies the effect of the oil pressure control, causing the oil pressure to be increased as a function of the engine speed and resulting in an increase in the lubrication provided to the engine as engine speeds are increased.
These and other features and advantages of the invention may be more fully understood from the following description of an exemplary embodiment, taken together with the accompanying drawings.
Referring now to
Also present in the crankcase 12, or mechanism compartment 15, is an engine oil pump 20 of a variable displacement vane type. The pump is shown with the drive cover removed to show the interior of the housing 22 defined within an outer wall 24 of the housing.
Within the housing is a rotor 26 having slots in which slidable vanes 28 are carried. The rotor is eccentric to the inner surface 30 of a cam ring 32 against which the vanes 28 slide to pump oil between an inlet port 34 and a pressurized outlet port 36. A guide ring 37, centered within the cam ring 32, guides the vanes outward to slide against the cam ring. The cam ring is pivotally connected to the inside of the outer wall 24 by a pivot 38 that allows oscillating motion of the cam ring within the housing. A seal 40 carried in the housing wall generally opposite to the pivot 38 separates the clearance surrounding the cam ring into a control chamber 42 and a vent chamber 44.
The control chamber 42 extends in the direction of pump rotation clockwise from the seal 40 to the pivot 38. An internal control orifice 46 connects the outlet port 36 and the control chamber 42 to supply outlet oil pressure to the control chamber.
The vent chamber 44 extends in the direction of pump rotation clockwise from the pivot 38 to the seal 40. Within the vent chamber, a tang 48 extends from the cam ring generally opposite from the pivot. The tang engages a biasing spring 50 extending within a spring chamber 52, forming part of the vent chamber 44, to the outer wall 24 of the housing 22 and urging the cam ring 32 in a direction to minimize the volume of the control chamber 42 and maximize the displacement of the pump 20 as is shown in
In accordance with the invention, the oil pump is mounted to the crankcase 12 with a portion of the outer wall 24, defining the spring chamber 52 and the vent chamber 44, located near the outer periphery 54 of a crankshaft counterweight 18 and forming a rotatable surface of the counterweight. The vent chamber is connected by a vent 56 through the outer wall 24 and facing toward the rotatable surface of the counterweight periphery 54 from a pocket 58 in the outer wall. A raised fin 60 on the outer wall extends close to the periphery 54 beyond the vent 56 in the direction of rotation of the crankshaft counterweight 18.
In operation, clockwise rotation of the crankshaft 16 and the counterweight 18 in the direction of the arrow 61, as shown in
As an example,
Various other rotatable engine and related components might be mentioned that could be used for developing usable pressures from the momentum of fluids such as air, oil, or mixtures carried along their rotating surfaces. Examples include camshafts, balance shafts, drive gears, chains, belts, transmission gears, flywheels and the like.
While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.
