Two stage pressure regulation system for variable displacement hydraulic pumps

A pump having a housing with an actuator member positioned inside for controlling the flow generated by the pump. A first decrease port is connected to the housing and has a surface area in operable contact with the actuator member. A second decrease port is connected to the housing and has a surface area that is operable contact with the actuator member. A valve is connected to the second decrease port for controlling the flow of fluid to the second decrease port. A suction passage is connected to the housing and drawings fluid to the housing using the actuator member. A discharge passage is connected to the housing so that fluid providing an exit for fluid that has been pressurized by the actuator member.

FIELD OF THE INVENTION

The present invention generally relates to the control of the output of a variable flow pump.

BACKGROUND OF THE INVENTION

It is desirable to properly lubricate the moving components in an internal combustion engine and provide hydraulic power. Typically, oil pumps used in engines are operably associated with the crankshaft of the engine (e.g., direct driven, chain driven, gear driven and/or the like) and have relatively simple fixed pressure regulation systems. While these systems are generally adequate, there are some disadvantages. For example, there is not much control of the actual discharge pressure relative to the pressure needed by the engine under certain/given operating conditions. By way of a non-limiting example, currently available pump technology typically provides high oil pressure at all engine operating conditions, where a lower oil pressure may be adequate at some of those engine conditions. Developing arrangements that provide less than high pressure outputs are desirable.

In commonly-assigned U.S. Pat. No. 6,896,489, the entire specification of which is expressly incorporated herein by reference, a mechanical hydraulic arrangement is shown for providing control of a variable displacement vane pump. This provides for a more optimized control of engine oil pressure. However, it is yet desirable to provide some further control depending on engine needs and/or variables.

SUMMARY OF THE INVENTION

A pump having a housing with an actuator member positioned inside for controlling the flow generated by the pump. A first decrease port is connected to the housing and has a surface area in operable contact with the actuator member. A second decrease port is connected to the housing and has a surface area that is operable contact with the actuator member. A valve is connected to the second decrease port for controlling the flow of fluid to the second decrease port. A suction passage is connected to the housing and draws fluid to the housing using the actuator member. A discharge passage is connected to the housing providing an exit for fluid that has been pressurized by the actuator member.

A further understanding of the present invention will be had in view of the description of the drawings and detailed description of the invention, when viewed in conjunction with the subjoined claims.

DETAILED DESCRIPTION OF THE INVENTION

The following description of the invention is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Referring to drawings generally, and specifically toFIGS. 1 and 2, a system and pump arrangement is shown. An oil pump40with either a variable displacement pump or a variable output pump element50. It should be appreciated that other types of pump systems can be used in the present invention, such as but not limited to other types of vane pumps, gear pumps, piston pumps, and/or the like.

In the engine system of the present invention, there is at least a lubrication circuit10, an oil sump20, an engine control unit (i.e., ECU) or computer30, and an oil pump40which draws oil from the oil sump20and delivers it at an elevated pressure to the lubrication circuit10.

The lubrication circuit10includes at least an oil filter11and journal bearings12supporting the engine's crankshaft, connecting rods and camshafts, and can contain a variable pressure transducer13. The lubrication circuit10can also optionally contain items such as an oil cooler, piston cooling jets, chain oilers, variable cam timing phasers, and cylinder deactivation systems. The ECU30includes electrical inputs for the measured engine speed31, engine temperature32, and engine load, torque or throttle33. The ECU30can also have an electrical input for the measured oil pressure34from the transducer13. The ECU30also has an output35for an electrical control signal to the oil pump40.

The oil pump40includes a housing41which contains a suction passage42, and a discharge passage and manifold43. The oil pump40can also include a pressure relief valve44and/or an internal oil filter45for cleaning the discharge oil for use inside the oil pump40. The oil pump40contains a variable flow pump element50, which has a positionable element, such as an eccentric ring51. The position of the eccentric ring in the pump element50determines the flow rate discharged by the pump element50at a given drive speed; and which forms in conjunction with the housing41two control chambers on the same side of the eccentric ring51, which contain fluid of controlled pressure for the intended purpose of exerting a control force on an area of the eccentric ring51. The first chamber or decrease chamber52, contains pressure applied to the eccentric ring51to decrease the flow rate of the variable flow pump element50to achieve a high pressure, and the second chamber or decrease chamber53, contains pressure applied to the eccentric ring51to decrease the flow rate of the variable flow pump element50to achieve a low pressure. The decrease chamber52is separated from the decrease chamber53by a wall.

A biasable member such as a spring54positioned between the housing41and the eccentric ring51. The spring54applies force to the eccentric ring51to increase the flow rate of the variable flow pump element50. The decrease chamber52and can be supplied with oil pressure from either the oil pump discharge manifold43or some other point downstream in the lubrication circuit10(e.g., usually from the main oil gallery15) that is inputted to the housing41through a first decrease port55. Pressure can be inputted to the second decrease port57from either the oil discharge manifold43via filter45and a channel62or some other point downstream in the lubrication circuit10(e.g., usually from the main oil gallery15) via output channel61. The pressure inputted to the second decrease port53can be controlled by a valve60which controls the flow of fluid from the sump20or from the discharge manifold43through a conduit68that is connected to the valve60.

The first decrease port55and second decrease port57provide separate fixed volumes of pressure that enter the decrease chambers52and53. The amount of pressure that fluid in the decrease chamber53applies to the eccentric ring51can be controlled by controlling the amount of fluid applied through the second decrease port57. The second decrease port57receives pressure from a conduit62. The pressure in the conduit62is controlled by the valve60. The valve60can be a solenoid valve. As shown inFIG. 2, the valve60is a solenoid controlled ball and tappet valve wherein the solenoid portion has a tappet63that applies force to move a ball64away from a seat66to allow pressure to flow from the conduit68to the conduit62. The solenoid60can be connected directly to the housing41of the pump or it may be placed at a downstream location. It is also possible to use some other type of valve, thus the present application is not limited to a solenoid ball valve application. The amount of pressure applied in the decrease chamber53will apply force on the eccentric ring51to decrease flow from the manifold43. The amount of pressure needed to decrease the flow can be predetermined by the force of the spring54which must be overcome to move the eccentric ring51. When pressure is no longer being supplied to the decrease chamber53, pressure in the chamber can be relieved through exhaust port59.

FIG. 3graphically illustrates the pressure versus pump speed applied to the eccentric ring51. A line102represents the pressure versus speed line for the first decrease port55. The second line104represents the pressure curve when the first decrease port55and second decrease port57apply pressure to the eccentric ring51.